Patent Application
20120153719
The present invention relates to a semiconductor element control device controlling semiconductor elements which perform switching operations to convert direct-current (DC) power to alternating-current (AC) power or AC power to DC power, and relates to an electrical machine system to be mounted on a vehicle having the semiconductor element control device.
A power inverter includes a function to convert DC power supplied from a DC power supply into AC power to be supplied to AC electrical load such as a rotating electrical machine or a function to convert AC power generated by a rotating electrical machine into DC power to be supplied to a DC power supply. To serve such conversion function, the power inverter includes an inverter circuit having plurality of switching elements. The switching elements repeat conduction operations and interruption operations so that power is converted from DC power to AC power or from AC power to DC power.
With a circuit that drives the switching elements described above, if there is no circuit for protection during an abnormality such as a power supply short circuit or the like, then there is a fear that excessively great current may flow in the switching elements, and that the circuit may be destroyed by heat generated in the elements or by a switching surge voltage, and this would be undesirable. A technology for suppressing overcurrent during this kind of short-circuit is described in Patent Document #1. According to Patent Document #1, it is described to detect overcurrent and short-circuit and to switch the IGBT to interrupting, on the basis of sense current for the IGBT,
Patent Document #1: Japanese Laid-Open Patent Publication Heisei 3-40517.
With a prior art power conversion device that detects overcurrent and short-circuit on the basis of sense currents as described in Patent Document #1 mentioned above, erroneous detection of overcurrent or short-circuit can easily occur if switching noise is present upon the sense currents due to the switching operation of the IGBT. It is desirable to reduce this type of erroneous detection as much as possible.
According to the first aspect of the present invention, a semiconductor element control device that controls a semiconductor element that performs switching operation for converting DC power into AC power, or AC power into DC power, comprises: a drive unit that outputs a drive signal for controlling the switching operation of the semiconductor element to a terminal of the semiconductor element; a short-circuit detection unit that detects short-circuit of the semiconductor element on the basis of the voltage at the terminal, and outputs a short-circuit detection signal; and a drive interruption unit that interrupts current flowing in the semiconductor element on the basis of the short-circuit detection signal output from the short-circuit detection unit.
According to the second aspect of the present invention, in the semiconductor element control device of the first aspect, it is preferred that the semiconductor element control device further comprises an overcurrent detection unit that detects overcurrent flowing in the semiconductor element on the basis of a sense current output by the semiconductor element, and outputs an overcurrent detection signal; and a filter unit that eliminates a noise component in the overcurrent detection signal output from the overcurrent detection unit; wherein the drive interruption unit, along with interrupting current flowing in the semiconductor element on the basis of the short-circuit detection signal, also interrupts current flowing in the semiconductor element on the basis of the overcurrent detection signal from which the noise component has been eliminated by the filter unit.
According to the third aspect of the present invention, a semiconductor element control device that controls a semiconductor element that performs switching operation for converting DC power into AC power, comprises: a drive unit that outputs a drive signal for controlling the switching operation of the semiconductor element to a terminal of the semiconductor element; a short-circuit detection unit that detects short-circuit of the semiconductor element on the basis of the voltage at the terminal and a sense current output by the semiconductor element, and outputs a short-circuit detection signal; and a drive interruption unit that interrupts current flowing in the semiconductor element on the basis of the short-circuit detection signal output from the short-circuit detection unit.
According to the fourth aspect of the present invention, in the semiconductor element control device of the third aspect, it is preferred that the semiconductor element control device further comprises an overcurrent detection unit that detects overcurrent in the semiconductor element on the basis of the voltage at the terminal and the sense current, and outputs an overcurrent detection signal; and a filter unit that eliminates a noise component in the overcurrent detection signal output from the overcurrent detection unit; wherein the drive interruption unit, along with interrupting current flowing in the semiconductor element on the basis of the short-circuit detection signal, also interrupts current flowing in the semiconductor element on the basis of the overcurrent detection signal from which the noise component has been eliminated by the filter unit.
According to the fifth aspect of the present invention, in the semiconductor element control device of the fourth aspect, it is preferred that the overcurrent detection unit detects overcurrent in the semiconductor element and outputs the overcurrent detection signal, when the voltage at the terminal exceeds a predetermined first voltage value, and also the sense current exceeds a predetermined first current value; and the short-circuit detection unit detects short-circuit of the semiconductor element and outputs the short-circuit detection signal, when the voltage at the terminal exceeds a predetermined second voltage value that is higher than or equal to the first voltage value, and also the sense current exceeds a predetermined second current value that is less than or equal to the first current value.
According to the sixth aspect of the present invention, an in-vehicle electrical system, comprising: an in-vehicle power supply that can be charged and discharged; a motor-generator that generates mechanical power on the basis of AC electrical power, and AC power on the basis of mechanical power; and a power conversion device that, along with converting DC power from the in-vehicle power supply to AC power that it supplies to the motor-generator, also converts AC power generated by the motor-generator to DC power with which it charges up the in-vehicle power supply; wherein the power conversion device comprises: a plurality of semiconductor elements that perform switching operation for converting DC power from the in-vehicle power supply into AC power, or AC power generated by the motor-generator into DC power; a drive unit that outputs drive signals for controlling the switching operation of the semiconductor element to terminals of the semiconductor element; a short-circuit detection unit that detects short-circuit of the semiconductor element on the basis of the voltage at the terminal, and outputs a short-circuit detection signal; and a drive interruption unit that interrupts current flowing in the semiconductor element on the basis of the short-circuit detection signal output from the short-circuit detection unit.
According to the seventh aspect of the present invention, in the in-vehicle electrical system of the sixth aspect, it is preferred that the in-vehicle electrical system further comprises an overcurrent detection unit that detects overcurrent flowing in the semiconductor element on the basis of sense current output by the semiconductor element, and outputs an overcurrent detection signal; and a filter unit that eliminates a noise component in the overcurrent detection signal output from the overcurrent detection unit; wherein the drive interruption unit, along with interrupting current flowing in the semiconductor element on the basis of the short-circuit detection signal, also interrupts current flowing in the semiconductor element on the basis of the overcurrent detection signal from which the noise component has been eliminated by the filter unit.
According to the eighth aspect of the present invention, an in-vehicle electrical system, comprises: an in-vehicle power supply that can perform charging and discharging; a motor-generator that generates mechanical power on the basis of AC electrical power, and AC power on the basis of mechanical power; and a power conversion device that, along with converting DC power from the in-vehicle power supply to AC power that it supplies to the motor-generator, also converts AC power generated by the motor-generator to DC power with which it charges up the in-vehicle power supply; wherein the power conversion device comprises: a plurality of semiconductor elements that perform switching operation for converting DC power from the in-vehicle power supply into AC power, or AC power generated by the motor-generator into DC power; a drive unit that outputs drive signals for controlling the switching operation of the semiconductor element to terminals of the semiconductor element; a short-circuit detection unit that detects short-circuit of the semiconductor element on the basis of the voltage at the terminal and sense current output by the semiconductor element, and outputs a short-circuit detection signal; and a drive interruption unit that interrupts current flowing in the semiconductor element on the basis of the short-circuit detection signal output from the short-circuit detection unit.
According to the ninth aspect of the present invention, in the in-vehicle electrical system of the eighth aspect, it is preferred that the in-vehicle electrical system further comprises an overcurrent detection unit that detects overcurrent flowing in the semiconductor element on the basis of the voltages at the terminals and the sense current, and outputs an overcurrent detection signal; and a filter unit that eliminates a noise component in the overcurrent detection signal output from the overcurrent detection unit; wherein the drive interruption unit, along with interrupting current flowing in the semiconductor element on the basis of the short-circuit detection signal, also interrupts current flowing in the semiconductor element on the basis of the overcurrent detection signal from which the noise component has been eliminated by the filter unit.
According to the tenth aspect of the present invention, in the in-vehicle electrical system of the ninth aspect, it is preferred that the overcurrent detection unit detects overcurrent flowing in the semiconductor element and outputs the overcurrent detection signal, when the voltage at the terminal exceeds a predetermined first voltage value, and also the sense current exceeds a predetermined first current value; and the short circuit detection unit detects short-circuit of the semiconductor element and outputs the short-circuit detection signal, when the voltage at the terminal exceeds a predetermined second voltage value that is less than or equal to the first voltage value, and also the sense current exceeds a predetermined second current value that is less than or equal to the first current value.
According to the present invention, it is possible to implement short circuiting protection with high reliability and with no erroneous detection of excessive current flow or short circuiting taking place, even if switching noise is present upon the sense currents or the like.
In the embodiment hereinafter described, the semiconductor element control device and an electrical machine system to be mounted on a vehicle with reference to the drawings. The semiconductor element control device according to an embodiment of the present invention is equipped in a power inverter which converts from DC power to AC power or from AC power to DC power and controls semiconductor elements which perform switching operations to perform such conversion of an electric power. A power inverter having a semiconductor element control device in accordance with the embodiment of the present invention is applicable to hybrid vehicles and ordinary electric vehicles. The control configuration and the circuit configuration of the power inverter to which the power inverter in accordance with the embodiment of the present invention is applied will be described with reference to the
The power inverter in accordance with the present embodiment will be described with an example of an in-vehicle power inverter of in-vehicle electric system to be mounted on a vehicle, particularly an inverter device for driving a vehicle that is used for an electric system for driving a vehicle in a challenging environment in terms of installation and operation. The inverter device for driving a vehicle is mounted on the electric system for driving a vehicle as a control device for controlling drive of electric machine for driving a vehicle, converts DC electric power which is supplied from an in-vehicle battery or power generating equipment into AC electric power, supplies the obtained AC electric power to the electric machine for driving a vehicle, and thus controls drive of the electric machine for driving a vehicle. Since the electric machine for driving a vehicle includes function as a generator, the inverter device for driving a vehicle converts AC electric power generated by the electric machine for driving a vehicle into DC electric power depending on operation mode. The converted DC electric power is supplied to the in-vehicle battery.
The configuration of the present embodiment is most appropriate for power inverters for driving vehicles such as automobiles and trucks. However, it is also applicable to other power inverters including power inverters for trains, ships, and airplanes, industrial power inverters used as a control device for electric machine which drives plant, or household power inverters used as a control device for electric machine which drives household solar power system or consumer electronics.
In
A front axle 114 is rotatably supported in a front part of the vehicle body. A pair of front wheels 112 are provided on both ends of the front axle 114. A rear axle (not herein figured) is rotatably supported in a rear part of the vehicle body. A pair of rear wheels (not herein figured) are provided on both ends of the rear axle. Even though a front-wheel drive system, in which main wheels powered by the engine are set to the front wheels 112 while driven wheels subordinated are set to the rear wheels, is applied to the HEV in the present embodiment, a rear-wheel drive system may be applied.
A front differential gear (Front DEF) 116 is provided in the center of the front axle 114. The front axle 114 is mechanically connected to an output side of the front DEF 116. An input side of the front DEF 116 is mechanically connected to an output shaft of a transmission 118. The front DEF 116 is a differential power transfer mechanism that distributes a rotational driving force with its speed reduced and transferred by the transmission 118 to the front axle 114 in right and left. Input of the transmission 118 is mechanically connected to output of the motor generator 192. An input side of the motor generator 192 is mechanically connected to an output side of the engine 120 and output of the motor generator 194 via a power transfer mechanism 122. The motor generators 192 and 194 and the power transfer mechanism 122 are contained in a chassis of the transmission 118.
The power transfer mechanism 122 is a differential mechanism made up of gears 123 to 130. The gears 125 to 128 are bevel gears. The gears 123, 124, 129, and 130 are spur gears. Power by the motor generator 192 is directly transferred to the transmission 118. An axis of the motor generator 192 is coaxial with the gear 129. This configuration makes the power transferred to the gear 129 directly transferred to the input side of the transmission 118, in the case when no electric power is supplied to the motor generator 192.
When the gear 123 is driven by the engine 120, the power of the engine 120 is transferred from the gear 123 to the gear 124, from the gear 124 to the both of the gears 126 and 128, from the both of the gears 126 and 128 to the gear 130, and lastly transferred to the gear 129. When the gear 125 is driven by the motor generator 194, rotation of the motor generator 194 is transferred from the gear 125 to the both of the gears 126 and 128, from the both of the gears 126 and 128 to the gear 130, and lastly transferred to the gear 129. For the power transfer mechanism 122, other mechanisms including a planetary gear mechanism may be applied in place of the differential mechanism described above.
Each of the motor generators 192 and 194 is the synchronous machine with permanent magnets in its rotor. Drive of the motor generators 192 and 194 is controlled by inverter devices 140 and 142 that control AC electric power supplied to armature coils of a stator of the motor generators 192 and 194. Since the inverter devices 140 and 142 are electrically connected to a battery 136, electric power is transferable between the battery 136 and each of the inverter devices 140 and 142.
In the present embodiment, a first motor-generator unit made up of the motor generator 192 and the inverter device 140 and a second motor-generator unit made up of the motor generator 194 and the inverter device 142 are provided and selectively used depending on the state of operation. In other words, in the case of assisting drive torque when the vehicle is driven by the power of the engine 120, the second motor-generator unit is operated as a generating unit by the power of the engine 120 for generating electric power, and the first motor-generator unit is operated as a motor unit by the electric power generated by the second motor-generator unit. In the case of assisting vehicle speed when the vehicle is driven by the power of the engine 120, the first motor-generator unit is operated as a generating unit by the power of the engine 120 for generating electric power, and the second motor-generator unit is operated as a motor unit by the electric power generated by the first motor-generator unit.
In the present embodiment, operating the first motor-generator unit as a motor unit by the electric power of the battery 136 enables the vehicle to be driven only by the power of the motor generator 192. In the present embodiment, the battery 136 is recharged by operating either the first motor-generator unit or the second motor-generator unit as a generating unit by either the power of the engine 120 or wheels.
The battery 136 is used as a battery for driving a motor 195 for auxiliaries. The auxiliaries include, for example, a motor for driving an air-conditioning compressor and a motor for driving a control hydraulic pump. DC electric power is supplied from the battery 136 to an inverter device 43, converted into AC electric power by the inverter device 43, and supplied to the motor 195. The inverter device 43 is provided with a similar function to that of the inverter devices 140 and 142, and controls phase, frequency and electric power of AC supplied to the motor 195. The motor 195 generates torque, for example, by supplying AC electric power of leading phase to rotation of a rotor of the motor 195. On the other hand, the motor 195 acts as an electric generator and operates regenerative braking, by generating AC electric power of lagging phase. The control function of the inverter device 43 is similar to that of the inverter device 140 or 142. Since capacity of the motor 195 is smaller than that of the motor generator 192 or 194, maximum conversion electric power of the inverter device 43 is smaller than that of the inverter device 140 or 142. Circuit configuration of the inverter device 43, however, is basically the same as that of the inverter device 140 or 142.
The inverter devices 140, 142, and 43, and a capacitor module 500 are in an electrically close relation between themselves, and commonly require measures against the heat and miniaturization of the devices. The power inverter detailed below thus contains the inverter devices 140, 142, and 43, and the capacitor module 500 in its chassis. This configuration realizes a small and reliable device.
Containing the inverter devices 140, 142, and 43, and the capacitor module 500 in the single chassis have advantageous effects in simplification of wiring and noise filtering. Inductance of the connection circuits between the capacitor module 500 and each of the inverter devices 140, 142, and 43 can also be reduced. Spike voltage and the heat are also reduced. Heat generation is reduced and radiation efficiency is thus improved.
Electric circuit configurations of the inverter devices 140, 142, and 43 will be described below with reference to
A power inverter 200 in accordance with the present embodiment is provided with the inverter device 140 and the capacitor module 500. The inverter device 140 is provided with an inverter circuit 144 and a control unit 170. The inverter circuit 144 is provided with a plurality of upper and lower arms series circuits 150 including an IGBT (insulated gate bipolar transistor) 328 and a diode 156 which operate as the upper arm and an IGBT 330 and a diode 166 which operate as the lower arm. Three of the upper and lower arms series circuits 150, 150, and 150 are illustrated in
The IGBTs 328 and 330 of the upper and lower arms are switching power semiconductor devices which are operated in response to drive signals output from the control unit 170 and convert DC electric power supplied from the battery 136 into three-phase AC electric power. The converted electric power is supplied to the armature coil of the motor generator 192. As described above, the inverter device 140 converts three-phase AC electric power generated by the motor generator 192 into DC electric power.
As shown in
The inverter circuit 144 is made up of a three-phase bridge circuit wherein the upper and lower arms series circuits 150, 150, and 150 for three phases are electrically connected in parallel between a DC positive terminal 314 and a DC negative terminal 316 that are electrically connected to the positive and negative terminals of the battery 136 respectively. The upper and lower arms series circuit 150 is called an arm and provided with the upper arm switching power semiconductor device 328, the diode 156, the lower arm switching power semiconductor device 330, and the diode 166.
In the present embodiment, the switching power semiconductor devices are illustrated by an example of the IGBTs 328 and 330. The IGBTs 328 and 330 are provided with collectors 153 and 163, emitters (signal emitter terminals 155 and 165), and gate electrodes (gate electrode terminals 154 and 164). As Figured, the diodes 156 and 166 are electrically connected between each of the collectors 153 and 163 and the emitters of the IGBTs 328 and 330, respectively. The diodes 156 and 166 are provided with two electrodes, i.e., cathode and anode electrodes. The cathode and anode electrodes are electrically connected to the collectors and emitters of the IGBTs 328 and 330 respectively so that the direction from the emitters to the collectors of the IGBTs 328 and 330 is forward direction. A MOSFET (metal-oxide semiconductor field-effect transistor) may be employed for the switching power semiconductor device which makes the diodes 156 and 166 unnecessary.
The upper and lower arms series circuits 150 are provided for three phases corresponding to each phase coil of the armature coil of the motor generator 192. Each of the three upper and lower arms series circuits 150 makes up either one of the U-phase, V-phase, or W-phase for the motor generator 192 through the intermediate electrodes 169 which connect the emitters of the IGBTs 328 with the collectors 163 of the IGBT 330 and the AC terminals 159. The upper and lower arms series circuits 150 are electrically connected in parallel between each other. The collectors 153 of the IGBTs 328 of the upper arm and the emitters of the IGBTs 330 of the lower arm are electrically connected by DC busbar to a positive electrode of the capacitor module 500 via the positive electrode terminal (P terminal) 157 and to a negative electrode of the capacitor module 500 via the negative electrode terminal (N terminal) 158, respectively. The intermediate electrodes 169, that is, the midpoints of each of the arms (connection of the emitters of the IGBTs 328 of the upper arm and the collectors of the IGBTs 330 of the lower arm), are electrically connected to the phase coil which corresponds to the armature coil of the motor generator 192 through an AC connector 188.
The capacitor module 500 constitutes a smoothing circuit which reduces fluctuation in DC voltage generated by switching operation of the IGBTs 328 and 330. The positive electrode and the negative electrode of the capacitor module 500 are electrically connected to positive and negative sides of the battery 136 through a DC connector 138 respectively. The capacitor module 500 is thus electrically connected in parallel to the battery 136 and the upper and lower arms series circuits 150 at both between the collectors 153 of the upper arm IGBTs 328 and the positive terminal side of the battery 136 and between the emitters of the lower arm IGBTs 330 and the negative terminal side of the battery 136.
The control unit 170 is designed to operate the IGBTs 328 and 330 and includes the control circuit 172 which generates a timing signal for controlling switching timing of the IGBTs 328 and 330 in accordance with information input from other control devices or sensors, and a drive circuit 174, which generates a drive signal for switching operation of the IGBTs 328 and 330 in accordance with the timing signal output from the control circuit 172.
The control circuit 172 is provided with a microcomputer for computational processing of the switching timing of the IGBTs 328 and 330. The microcomputer is provided with input information including a target torque required for the motor generator 192, a current value supplied from the upper and lower arms series circuits 150 to the armature coil of the motor generator 192, and a magnetic pole position of the rotor of the motor generator 192. The target torque is set in accordance with a command signal output from a superordinate control device not figured herein. The current value is detected in accordance with a detection signal output from a current sensor 180. The magnetic pole position is detected based on a detection signal output from a rotating magnetic pole sensor (not Figured herein) provided in the motor generator 192. In the present embodiment, description will be given with an example of detection of three-phase current value. Two-phase current value, however, may instead be detected.
The microcomputer in the control circuit 172 calculates a current command value of d- and q-axis of the motor generator 192 in accordance with the target torque, calculates a voltage command value of the d- and q-axis in accordance with the difference between the calculated current command value of the d- and q-axis and a detected current value of the d- and q-axis, and converts the calculated voltage command value of the d- and q-axis into a voltage command value for U-phase, V-phase, and W-phase in accordance with the detected magnetic pole position. The microcomputer generates a pulse modulated wave according to comparison of a fundamental wave (sine wave) based on the voltage command value for U-phase, V-phase, and W-phase with a carrier wave (triangle wave), and outputs the generated modulated wave to the gate drive circuit 174 as a pulse-width modulation (PWM) signal.
When the lower arm is driven, the gate drive circuit 174 amplifies and outputs the PWM signal as a drive signal to the gate electrodes of the IGBTs 330 of the corresponding lower arm. When the upper arm is driven, the gate drive circuit 174 shifts from a reference potential level of the PWM signal to a reference potential level of the upper arm, amplifies and outputs the amplified PWM signal as a drive signal to the gate electrodes of the IGBTs 328 of the corresponding upper arm. Each of the IGBTs 328 and 330 performs switching operation in response to the input drive signals.
The gate drive circuit 174 detects abnormality (short-circuit, overcurrent, overvoltage, over temperature, etc.) for protecting the upper and lower arms series circuits 150. Consequently, sensing information is input to the gate drive circuit 174. For example, information of gate voltage on each of the IGBTs 328 and 330 is input to a drive unit (IC) of the corresponding drive circuit 174. Each input to a drive unit (IC) detects short-circuit, stops switching operation of the corresponding IGBTs 328 and 330 in the case short-circuit is detected, and protects the corresponding IGBTs 328 and 330 from short-circuit. Information of collector current which flows through each of the IGBTs 328 and 330 is input to a drive unit (IC) of the corresponding drive circuit 174. Each drive unit (IC) thus detects overcurrent, stops switching operation of the corresponding IGBTs 328 and 330 in the case overcurrent is detected, and protects the corresponding IGBTs 328 and 330 from overcurrent. These protection operations during short-circuit and overcurrent will be explained precisely later.
Temperature information of the upper and lower arms series circuits 150 is input from a temperature sensor (not figured herein) provided to a drive unit (IC) of the corresponding drive circuit 174. Voltage information of positive side of DC of the upper and lower arms series circuits 150 is input to the corresponding drive circuit 174. Each drive unit (IC) detects over temperature and overvoltage based on those information, stops all switching operations of the IGBTs 328 and 330 in the case over temperature or overvoltage is detected, and protects the upper and lower arms series circuits 150 and therefore the semiconductor module which includes the circuits 150 from over temperature or overvoltage.
In
As illustrated, the upper and lower arms series circuit 150 is provided with the positive terminal (P terminal) 157, the negative terminal (N terminal) 158, the AC terminals 159 from the intermediate electrode 169 of the upper and lower arms, the signal emitter terminal 155 of the upper arm, the gate electrodes terminal 154 of the upper arm, the signal emitter terminal 165 of the lower arm, and the gate electrodes terminal 164 of the lower arm. The power inverter 200 is provided with the DC connector 138 on its input side and the AC connector 188 on its output side, and is connected to each of the battery 136 and the motor generator 192 via each of the connectors 138 and 188. A power inverter with circuit configuration in which two of the upper and lower arms series circuits are connected in parallel to each phase may be employed for a circuit that generates outputs of each phase of the three-phase AC which is output to the motor generator.
Next, the protection operation during short-circuit and overcurrent will be explained. In this embodiment, as previously described, during short-circuit and overcurrent, protection operation is performed by a semiconductor element control device having various types, including the drive circuit 174. In the following, as an example, the operation of the IGBT 330 and one of the diodes 166 as a lower arm in the inverter circuit 144 of
In
The gate voltage of the IGBT 330 is input to a short-circuit detection unit 806 within the drive circuit 174. This short-circuit detection unit 806 performs detection of short-circuit of the IGBT 330 by comparing together the gate voltage that is input and a reference voltage that is set according to a predetermined short-circuit detection level. If short-circuit has been detected, then the short-circuit detection unit 806 outputs a short-circuit detection signal to the drive interruption unit 804.
The drive interruption unit 804 determines that the IGBT 330 is in an overcurrent state or is in a short-circuit state when either an overcurrent detection signal from the overcurrent detection unit 802 has passed through the noise filter 803 and has been input, or when a short-circuit detection signal has been input from the short-circuit detection unit 806. And the unit 804 outputs an abnormality interrupting signal to the drive unit 805 for interrupting the current flowing in the IGBT 330. Now, the drive unit 805 outputs a drive signal to the gate terminal of the IGBT 330 for controlling the switching operation of the IGBT 330 on the basis of the PWM signal output from the control circuit 172 of
The operation of the semiconductor element control device of
Moreover, if the motor is suffering a short to ground or a short to power, then when the IGBT 330 is in turned-on the IGBT 330 goes into the short-circuit state, and a rather large short-circuit current flows in the IGBT 330. At this time the power supply voltage applied between the collector and the emitter of the IGBT 330 momentarily drops, and then this voltage spikes upward. And a current that is generated according to the change of this voltage over time and according to the feedback capacitance of the IGBT 330 flows to the gate of the IGBT 330. Due to this, the phenomenon occurs of the gate voltage spiking up to higher than the power supply voltage (the “spike” phenomenon). The short-circuit detection unit 806 detects short-circuit of the IGBT 330 by employing this spike phenomenon of the gate voltage during short-circuit. For example, a predetermined voltage level that is higher than the gate power supply voltage may be taken as being a short-circuit detection level Vg2. The short-circuit detection unit 806 inputs the gate voltage Vg of the IGBT 330, and, if this gate voltage Vg is greater than the short-circuit detection level Vg2, then it detects that short-circuit has taken place and outputs a short-circuit detection signal. And this short-circuit detection signal from the short-circuit detection unit 806 is input to the drive interruption unit 804.
When the drive interruption unit 804 receives an overcurrent detection signal from the overcurrent detection unit 802 or a short-circuit detection signal from the short-circuit detection unit 806 as described above, then it outputs an abnormality interrupting signal to the drive unit 805. And, apart from the drive unit 805 receiving a PWM signal from the control circuit 172 and outputting a gate drive voltage to turn the IGBT 330 on or off, it also cuts off the IGBT 330 by software when it receives an abnormality interrupting signal from the drive interruption unit 804. The drive unit 805 is also endowed with a function of gate short-circuit, in which it lowers the gate voltage to low impedance with respect to the emitter of the IGBT 330, if the gate voltage becomes a predetermined voltage that is lower than the threshold value of the IGBT 330, for example 3 V.
It should be understood that sometimes it may be the case that the output of the overcurrent detection comparator 903 fluctuates, since the sense voltage Vs is subject to the switching noise of the IGBTs 330. This type of fluctuation of the output of the overcurrent detection comparator 903 is associated with erroneous detection of overcurrent. Because of this, the output fluctuation of the overcurrent detection comparator 903 due to noise is suppressed by cutting out, as being noise components, voltage signals of a predetermined frequency and higher that are output from the overcurrent detection comparator 903. The filter time constant of the noise filter 803 is smaller than the time constant of a filter (not shown in the figures) that is used during normal operation.
And the short-circuit detection unit 806 is constituted by a comparator 905 for short-circuit detection. The gate voltage Vg is input to one side of this short-circuit detection comparator 905, for example to its non-inverting input side. Moreover, a reference voltage that is equivalent to the predetermined short-circuit detection level Vg2 is input to its other input side, for example to its inverting input side. It should be understood that the short-circuit detection level Vg2 is higher than the gate power supply voltage. The output of the short circuit detection comparator 905 is low level in the normal operational state of the IGBT 330, since the gate voltage Vg is lower than the short-circuit detection level Vg2. On the other hand, when the IGBT 330 goes into the short-circuit state, the output of the short circuit detection comparator 905 goes to high level, since the gate voltage Vg becomes higher than the short-circuit detection level Vg2. According to this arrangement, a short-circuit detection signal is output from the short-circuit detection unit 806 by the output from the overcurrent detection comparator 905 changing from low level to high level. When the output of the short-circuit detection comparator 905 goes to high level, the drive interruption unit 804 determines that there is an abnormality short-circuit state, and outputs a latch signal to the drive unit 805 as an abnormality interrupting signal.
It should be understood that the circuit structures for the overcurrent detection unit 802 and for the short-circuit detection unit 806 explained above are only given by way of example, and their details should not be considered as being limitative. It would also be acceptable to arrange to provide different circuit structures for implementing the same functions.
In
As shown in
On the other hand it will be understood that, during the overcurrent abnormality 1009, the collector current 1003 exceeds the overcurrent detection level Ic1. At this time, by setting the previously described overcurrent level Vs1 in advance to correspond to the overcurrent detection level Ic1, an overcurrent state is detected by the overcurrent detection unit 802, and an overcurrent detection signal is output from the overcurrent detection unit 802. As a result, the gate voltage 1001 is interrupted in software by the drive unit 805.
Furthermore it will be understood that, during the short-circuit abnormality 1010, after the collector voltage 1002 has instantaneously dropped in correspondence to the start of the flow of short-circuit current in the IGBT 330, it returns to the neighborhood of the power supply voltage. At this time, as previously described and as shown by the reference symbol 1011, the gate voltage 1001 spikes up to greater than or equal to the power supply voltage, due to a current corresponding to the change over time of the collector voltage 1002 and corresponding to the feedback capacitance of the IGBT 330 flowing to the gate of the IGBT 330. And when, due to this spike phenomenon, the gate voltage 1001 exceeds the short-circuit detection level Vg2 shown by the reference symbol 1004, then a short-circuit state is detected by the short-circuit detection unit 806, and a short-circuit detection signal is output from the short-circuit detection unit 806. As a result, short-circuit protection operation for the IGBT 330 is performed by the drive unit 805.
When detecting overcurrent and short-circuit on the basis of a sense current as in the prior art, it is necessary to set the short-circuit detection level to be greater than the overcurrent detection level, in consideration of fluctuations of the sense current. Due to this, it is not possible to perform protection against short-circuit in a manner appropriate for incomplete short-circuit, such as when the short circuit current stops at an intermediate level between the overcurrent detection level and the short-circuit detection level. On the other hand since, with the present invention, as explained in the above description, the phenomenon that the gate voltage exhibits a spiking up characteristic during short-circuit is taken advantage of in order to detect the short-circuit, accordingly it is possible to detect incomplete short-circuit as well. Therefore the possibilities of erroneous detection of short-circuit or of failure of short-circuit protection due to fluctuation of the sense current are eliminated, so that it is possible to implement highly reliable short-circuit protection.
According to this embodiment as explained above, the following beneficial operational effects are obtained.
(1) The short-circuit detection unit 806 detects short-circuit of the IGBT 330 on the basis of the gate terminal voltage of the IGBT 330, and outputs a short-circuit detection signal if short-circuit has been detected. And, on the basis of the short-circuit detection signal output from the short-circuit detection unit 806, the drive interruption unit 804 interrupts the flow of current to the IGBT 330 by outputting an abnormality interrupting signal to the drive unit 805. Since, due to this, it is arranged to take advantage of the phenomenon that the gate voltage exhibits a spiking up characteristic during short-circuit in order to detect the short-circuit, accordingly there is no possibility of erroneous detection of short-circuit even if the sense current carries switching noise or the like, so that it is possible to implement highly reliable short-circuit protection.
(2) The overcurrent detection unit 802 detects the flowing of overcurrent in the IGBT 330 on the basis of the sense current output by the IGBT 330, and outputs an overcurrent detection signal if overcurrent has been detected. And, along with interrupting the flow of current to the IGBT 330 on the basis of the short-circuit detection signal output from the short-circuit detection unit 806 as described above, the drive interruption unit 804 also interrupts the flow of current to the IGBT 330 by outputting an abnormality interrupting signal to the drive unit 805 on the basis of the overcurrent detection signal from which the noise component has been eliminated by the noise filter 803. Due to these arrangements, in addition to the possibility of short-circuit being eliminated, it is also possible to eliminate erroneous detection of overcurrent, so that it is possible to implement highly reliable short-circuit protection.
Next, a second embodiment of the present invention will be explained. In this embodiment, a different semiconductor element control device is used from the one explained above for the first embodiment. It should be understood that since, for this embodiment, the circuit structure of the control blocks and the in-vehicle control system of the hybrid automobile are the same as those for the first embodiment as shown in
The portions where
The overcurrent detection unit 802 performs detection of overcurrent flowing in the IGBT 330 on the basis of the result of comparison between the sense voltage that is input and a reference voltage that is set according to a predetermined overcurrent detection level, and on the basis of the result of comparison between the gate voltage that is input and a reference voltage that is set according to a predetermined overcurrent detection level. In other words, overcurrent is detected when the sense voltage Vs is above a predetermined overcurrent detection level Vs1, and moreover the gate voltage Vg is above a predetermined overcurrent detection level Vg1. It should be understood that the overcurrent detection level Vg1 for the gate voltage Vs is a voltage that is higher than the threshold voltage for turning the IGBT 330 on. Moreover, the overcurrent detection level Vs1 for the sense voltage Vs is a voltage that, for example, may correspond to around twice the rated current of the IGBT 330. If overcurrent has been detected, then, in a similar manner to the case with
The short-circuit detection unit 806 performs detection of short-circuit of the IGBT 330 on the basis of the result of comparison between the sense voltage that is input and a reference voltage that is set according to a predetermined short-circuit detection level, and on the basis of the result of comparison between the gate voltage that is input and a reference voltage that is set according to a predetermined short-circuit detection level. In other words, short-circuit is detected when the sense voltage Vs is above a predetermined short-circuit detection level Vs2, and moreover the gate voltage Vg is above a predetermined short-circuit detection level Vg2. It should be understood that it is desirable for the short-circuit detection level Vg2 for the gate voltage Vs to be a voltage that is higher than the above described overcurrent detection level Vg1. On the other hand, it is desirable for the short-circuit detection level Vs2 for the sense voltage Vs to be a voltage that is less than or equal to the above described overcurrent detection level Vs1. With these arrangements, while on the one hand preventing erroneous detection of short-circuit, even if short-circuit takes place of a type in which the short-circuit current stops between the overcurrent detection level Vs1 and the short-circuit detection level Vs2, still it is possible to detect this with the short-circuit detection unit 806. If short-circuit has been detected, then, in a similar manner to the case with
The gate voltage Vg is input to one of the input sides of the overcurrent detection comparator 902, for example to its non-inverting input side. Moreover, a reference voltage that corresponds to the overcurrent detection level Vg1 is input to its other input side, for example to its inverting input side. And, in a similar manner to the case with
In the normal operational state of the IGBT 330, the output of the overcurrent detection comparator 903 is low level, since the sense voltage Vs is lower than the overcurrent detection level Vs1. Due to this, the output of the AND circuit for overcurrent detection 901 is low level, irrespective of the output of the overcurrent detection comparator 902. On the other hand, when the IGBT 330 goes into an overcurrent state, the output of the overcurrent detection comparator 903 becomes high level, since the sense voltage Vs now comes to be higher than the overcurrent detection level Vs1. Furthermore, since the gate voltage Vg is higher than the overcurrent detection level Vg1, accordingly the output of the overcurrent detection comparator 902 is also high level. Thus, the output of the AND circuit for overcurrent detection 901 goes to high level. With these arrangements, and due to the output from the AND circuit for overcurrent detection 901 changing from low level to high level, a latch signal is output from the overcurrent detection unit 802 as an overcurrent detection signal (i.e. as an abnormality interrupting signal).
It should be understood that the noise component in the output from the AND circuit for overcurrent detection 901 is cut down by the noise filter 803. Due to this, fluctuations of the output of the AND circuit for overcurrent detection 901 that originate when the output of the overcurrent detection comparator 903 fluctuates due to switching noise from the IGBT 330 carried upon the sense voltage Vs are suppressed.
The short-circuit detection unit 806 includes an AND circuit 904 for short-circuit detection and comparators 905 and 906 for short-circuit detection. It should be understood that the short-circuit detection comparator 905 is the same as the one in the first embodiment shown in
In a similar manner to the case in
In the normal operational state of the IGBT 330, the output of the short-circuit detection comparator 905 is low level, since the gate voltage Vg is lower than the short-circuit detection level Vg2. Due to this, the output of the AND circuit for short-circuit detection 904 is low level, irrespective of the output of the short-circuit detection comparator 906. On the other hand, when the IGBT 330 goes into a short-circuit state, the output of the short-circuit detection comparator 905 becomes high level, since the gate voltage Vg now comes to be higher than the short-circuit detection level Vg2. Furthermore, since the sense voltage Vs is higher than the short-circuit detection level Vs2, accordingly the output of the short-circuit detection comparator 906 is also high level. Thus, the output of the AND circuit for short-circuit detection 904 goes to high level. With these arrangements, and due to the output from the AND circuit for short-circuit detection 904 changing from low level to high level, a latch signal is output from the short-circuit detection unit 806 as a short-circuit detection signal (i.e. as an abnormality interrupting signal).
It should be understood that the circuit structures for the overcurrent detection unit 802 and for the short-circuit detection unit 806 explained above are only given by way of example, and their details should not be considered as being limitative. It would also be acceptable to arrange to provide different circuit structures for implementing the same functions.
In
As shown in
On the other hand it will be understood that, during the abnormality overcurrent state 1009, the collector current 1003 exceeds the overcurrent detection level Ic1, and moreover the gate voltage 1001 exceeds the overcurrent detection level Vg1 denoted by the reference symbol 1005. At this time, by setting the previously described overcurrent level Vs1 in advance so as to correspond to the overcurrent detection level Ic1, an overcurrent state is detected by the overcurrent detection unit 802, and an overcurrent detection signal is output from the overcurrent detection unit 802. As a result, the gate voltage 1001 is interrupted in software by the drive unit 805.
Furthermore, during the abnormality short-circuit state 1010, due to the spiking up phenomenon as shown by the reference symbol 1011, the gate voltage 1001 exceeds the short-circuit detection level Vg2 shown by the reference symbol 1004, and moreover the collector current 1003 exceeds the short-circuit detection level Ic2 shown by the reference symbol 1007. At this time, due to the short-circuit detection level Vs2 being set in advance to correspond to the short-circuit detection level Ic2 as previously described, a short circuited state is detected by the short-circuit detection unit 806, and a short-circuit detection signal is output from the short-circuit detection unit 806. As a result, short-circuit protection operation for the IGBT 330 is performed by the drive unit 805.
According to this embodiment as explained above, the following beneficial operational effects are obtained.
(1) The short-circuit detection unit 806 detects short-circuit of the IGBT 330 on the basis of the gate terminal voltage of the IGBT 330 and the sense current output by the IGBT 330, and outputs a short-circuit detection signal if short-circuit has been detected. Moreover, the overcurrent detection unit 802 detects overcurrent flowing in the IGBT 330 on the basis of the gate terminal voltage of the IGBT 330 and the sense current output by the IGBT 330, and outputs an overcurrent detection signal if overcurrent has been detected. Since this is done, it is possible to perform short-circuit detection and overcurrent detection with even higher reliability, as compared with the first embodiment.
(2) The overcurrent detection unit 802 detects that overcurrent is flowing in the IGBT 330 and outputs an overcurrent detection signal, when the gate terminal voltage of the IGBT 330 exceeds the predetermined overcurrent detection level Vg1 and moreover the sense current output by the IGBT 330 has exceeded the predetermined overcurrent detection level Ic1. Moreover, the short-circuit detection unit 806 detects short-circuit of the IGBT 330 and outputs a short-circuit detection signal, when the gate terminal voltage of the IGBT 330 exceeds the predetermined short-circuit detection level Vg2 that is greater than or equal to the overcurrent detection level Vg1 and moreover the sense current output by the IGBT 330 has exceeded the predetermined short-circuit detection level Ic2 that is less than or equal to the overcurrent detection level Ic1. With these arrangements, on the one hand erroneous detection of short-circuit by the short-circuit detection unit 806 is prevented, and also, even if short-circuit occurs in such a manner that the short-circuit current stops between the overcurrent detection level and the short-circuit detection level, still it is possible for this to be detected by the short-circuit detection unit 806.
The circuit block diagram of
The circuit block diagram of
In
It should be understood that the various embodiments and variant embodiments explained above may also be combined in various ways. And the variant embodiments may also be combined in any desired manner.
While, in the various embodiments and variant embodiments explained above, examples of semiconductor element control devices provided with both an overcurrent detection unit 802 and a short-circuit detection unit 806 have been described, it would also be acceptable to arrange to provide only one or the other of these elements. In other words, the present invention could also be applied to a semiconductor element control device that performs one or the other of overcurrent detection and short-circuit detection using a method as described above, and that executes protective operation for the circuitry according to the result of that detection.
The above explanation is only an example; the present invention is not to be considered as being limited by the structure of the embodiments described above.
43: inverter device for auxiliary machinery
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-172103 | Jul 2009 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2010/062324 | 7/22/2010 | WO | 00 | 3/7/2012 |
