Patent Application
20120262096
Pursuant to 35 U.S.C. §119(a), this application claims the benefit of earlier filing date and right of priority to Korean Application No. 10-2011-0034344 filed on Apr. 13, 2011, the contents of which are incorporated by reference herein in its entirety.
1. Field of the Disclosure
The present disclosure relates to an electric vehicle in which a battery is charged using a drive motor.
2. Background of the Disclosure
Electric vehicle (EV) refers to a vehicle using a battery and an electric motor without using petroleum fuel and an engine. The electric vehicle can be largely classified into an electric vehicle using only an electric battery and a hybrid electric vehicle using other power sources such as gasoline and the electric battery together. An electric vehicle in which a motor is rotated by electricity stored in a battery to drive the vehicle was first manufactured before 1873 when a gasoline vehicle was manufactured. However, the electric vehicle was not put to practical use due to the problems of a heavy weight of battery, the time taken for charging, and the like. In recent years, studies for electric vehicles have been actively carried out due to the problems of a shortage of energy resources such as fossil fuels, environmental pollution caused by gasoline vehicles, and the like.
An electric vehicle uses a blushless DC motor or induction motor as a driving motor, or modifies them as necessary prior to use. Furthermore, the electric vehicle may include a drive inverter for driving a motor and an on-board charge (OBC) for charging a battery in an independent manner. When the electric vehicle is driven, only the drive inverter is used without using the OBC. On the contrary, when the electric vehicle is in an idle state, only the OBC is used without using the drive motor.
According to the embodiments of the present disclosure, an object thereof is to provide an electric vehicle and a driving method thereof capable of maintaining the function of an inverter included in a motor control device as well as using it as a charging device to charge a battery.
According to the embodiments of the present disclosure, another object thereof is to provide an electric vehicle and a driving method thereof capable of performing a driving and charging operation using a drive inverter and coils in a three-phase motor.
In order to accomplish the foregoing object, an electric vehicle according to an embodiment may include a battery to supply direct current power, an inverter including three inverter modules to convert the direct current power into three-phase alternating current power, at least one inverter module including two switching units, a three-phase motor having three phase coils connected to the three inverter modules, respectively, to be driven by the three-phase alternating current power, wherein one side of the three phase coils are connected to the three inverter modules, respectively, and another side of two coils out of the three phase coils are connectable to a charging power, and another side of remaining coil out of the three phase coils is connectable to the battery.
The electric vehicle may further include a controller to output a control signal to the inverter to drive the three inverter modules. Also, the electric vehicle may further include at least one switch unit provided between the battery and the direct current link capacitor to separate a connection between the battery and the direct current link capacitor when charging the battery.
In order to accomplish the foregoing object, an electric vehicle according to another embodiment may include a battery to supply direct current power, a direct current link capacitor to smooth out and store the direct current power, an inverter including three inverter modules to convert the direct current power smoothed out by the direct current link capacitor into three-phase alternating current power according to a control signal, at least one inverter module including two switching units having switching elements and diodes connected in parallel with the switching elements, a three-phase motor having three phase coils connected to the three inverter modules to be driven by the three-phase alternating current power, and a controller to output a control signal to the inverter to drive the inverter, wherein the switching elements are switched according to the control signal when driving the electric vehicle, and opened when charging the battery.
In order to accomplish the foregoing objects, a method of driving an electric vehicle according to an embodiment may include sensing whether a charging power is connected to the electric vehicle, connecting the three phase coils to one neutral point, and outputting the control signal to the inverter to drive the three-phase motor when the sensing indicates that the charging power is not connected to the electric vehicle, and connecting two coils out of the three phase coils to the charging power, and connecting remaining one coil out of the three phase coils to the battery to charge the battery when the sensing indicates that the charging power is connected to the electric vehicle.
According to the embodiments of the present disclosure, it may be possible to drive an electric vehicle using a drive inverter and coils within a three-phase motor, and charge a battery using them as a charging device.
According to the embodiments of the present disclosure, coils included in a motor control device and switching elements within an inverter may be used, and the use of the inductor and switching elements required for the charging device may be reduced, thereby reducing the cost as well as decreasing the size of a system.
The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the principles of the disclosure.
In the drawings:
Referring to
The power module 150 may include a motor control device 200 for receiving direct current power from the battery 100, and a three-phase motor 300 configured to be driven by the motor control device 200 to generate a rotational force.
The battery 100 supplies direct current power to the power module 150. The battery 100 forms a set in which a plurality of unit cells are connected in series and/or parallel. The plurality of unit cells are managed to maintain a constant voltage by a battery management system (BMS). In other words, the battery management system allows the battery 100 to output a constant voltage. The battery 100 may be preferably configured with a secondary cell capable of performing a charging and discharging operation, but not be limited to this. In general, nickel-metal hydride (Ni-MH) batteries, lithium ion (Li-ion) batteries, or the like may be used for the battery 100.
The motor control device 200 receives direct current power from the battery 100. The motor control device 200 converts direct current power received from the battery 100 into alternating current power and supplies it to the three-phase motor 300. In general, the motor control device 200 supplies three-phase power to the motor.
The three-phase motor 300 may include a stator (not shown) being stationary with no rotation, and a rotor (not shown) being rotated, and the three-phase motor 300 receives alternating current power supplied from the motor control device 200 to generate a rotational force. If alternating current power is applied to the three-phase motor 300, then the stator of the three-phase motor 300 receives alternating current to generate a magnetic field. In case of a motor having a permanent magnet, a magnetic field generated from the stator repulses a magnetic field of the permanent magnet provided in the rotor to rotate the rotor. A rotational force is generated by the rotation of the rotor.
A drive gear (not shown) may be provided at one side of the three-phase motor 300. The drive gear converts a rotational force of the three-phase motor 300 according to a gear ratio. The rotational force outputted from the drive gear is transferred to a front wheel 510 and/or rear wheel 520 to move the vehicle.
The front suspension device 610 and rear suspension device 620 support the front wheel 510 and rear wheel 520, respectively, with respect to a vehicle body. The front suspension device 610 and rear suspension device 620 do not allow vibration of the road surface to be transferred to the vehicle body by means of a spring or damping mechanism.
The front wheel 510 may further include a steering device (not shown). The steering device is a device of controlling the direction of the front wheel 510 to move a vehicle in a direction consistent with the driver's intention.
Referring to
The electric vehicle may further include a direct current-direct current converter (not shown) for converting a driving power of the battery 100 into a constant direct current voltage. The direct current-direct current (DC-DC) converter may include switching elements, for example, insulated gate bipolar transistors (hereinafter, referred to as “IGBTs”) which are driven according to a control signal of the controller. Furthermore, the converter may further include a reactor if necessary.
The direct current link capacitor 210 is connected between the battery 100 and the inverter 230 to smooth out and store an output direct current voltage of the battery.
Referring to
The three-phase motor 300 may include three phase coils 310, 320, 330 connected to the three inverter modules to be driven according to the three-phase alternating current power. The controller 250 generates the control signal and outputs it to the inverter 230 to drive the three inverter modules.
As illustrated in
Referring to
Referring to
The controller 250 may include a coordinate conversion unit for converting a motor drive current into a synchronous coordinate system, and a current controller for receiving a torque instruction and a magnetic flux instruction, and receiving the motor drive current converted through the coordinate conversion unit to output a voltage instruction. The controller 250 may further include a pulse width modulation controller for generating a control signal that drives an inverter based on the voltage instruction to output it to the inverter 230.
The current controller receives a current instruction and a motor drive current, and outputs a voltage instruction. The current controller receives a d-axis current instruction (ie*ds) and a q-axis current instruction (ie*qs). The current controller proportionally integrates and filters the q-axis current instruction (ie*qs) to output a q-axis synchronous coordinate system voltage instruction (Ve*qs). In other words, the current controller compares the q-axis current instruction (ie*qs) with the q-axis output current (ieq) into which a motor drive current has been coordinate-converted by the coordinate conversion unit, and proportionally integrates and filters its difference, i.e., current error, to output q-axis voltage instruction (Ve*q). Meanwhile, the current controller also proportionally integrates and filters the d-axis current instruction (ie*ds) to output d-axis voltage instruction (Ve*d). In other words, the current controller compares the d-axis current instruction (ie*ds) with the d-axis output current (ied) into which the motor drive current has been coordinate-converted, and proportionally integrates and filters its difference, i.e., current error, to output d-axis voltage instruction (Ve*d) to the PWM controller. Here, “e” denotes a synchronous coordinate system.
The PWM controller combines effective voltage vectors that can be outputted from the inverter 230 during a control period (Ts) and generates the control signal so as to follow the voltage instruction to output it to the inverter 230. The control signal is a gating signal input to a gate of the IGBT.
The controller 250 may further include a synchronous coordinate inverse conversion unit for converting a synchronous coordinate system voltage instruction into a stationary coordinate system voltage instruction. The synchronous coordinate inverse conversion unit is disposed between the current controller and PWM controller to convert a synchronous coordinate system voltage instruction (Ve*d, Ve*q) into (Vs*d, Vs*q) which is a stationary coordinate system voltage instruction (Vs*). Here, “e” denotes a synchronous coordinate system, and “s” denotes a stationary coordinate system. The PWM controller converts a voltage instruction of the stationary coordinate system into a suitable form of a motor to be driven to output it. The PWM controller converts a voltage instruction of the stationary coordinate system into a three-phase voltage instruction (Va*, Vb*, Vc*) and outputs it to the three-phase motor 300. The synchronous coordinate inverse conversion unit may be included in the PWM controller. The PWM controller generates a control signal based on a voltage instruction for each phase, and outputs the control signal to the inverter to turn on or off switching elements in the inverter.
Referring to
The direct current link capacitor 210 is connected between the converter and the inverter 230 or between the battery 100 and the inverter 230 to smooth out and store an output direct current voltage of the battery.
The inverter 230 may include three inverter modules 231, 232, 233 configured with two switching units. Furthermore, the inverter 230 converts the direct current power smoothed out by the direct current link capacitor 210 into three-phase alternating current power according to a control signal. The switching unit may include switching elements driven by a control signal and diodes connected in parallel with the switching elements, respectively. The switching elements are switching elements such as MOSFETs, IGBTs, or the like.
The three-phase motor 300 may include three phase coils 310, 320, 330 connected to the three inverter modules to be driven according to the three-phase alternating current power. The controller 250 generates the control signal and outputs it to the inverter 230 to drive the three inverter modules.
When driving an electric vehicle, namely, when driving a three-phase motor, the three phase coils 310, 320, 330 are connected to one neutral point 340. On the contrary, as illustrated in
Referring to
Referring to
Referring to
The step of charging the battery (S300) may include converting the charging power into direct current power (S320) and boosting or bucking the direct current power to supply it to the battery (S330). Furthermore, the step of charging the battery (S300) may further include separating a connection between the battery and the direct current link capacitor (S310).
Referring to
Referring to
The step of driving the three-phase motor (S200) may include connecting the battery with the direct current link capacitor (S210), and applying the three-phase alternating current power to the three phase coils to drive the electric vehicle (S240). Furthermore, the step of driving the three-phase motor (S200) may further include smoothing out a driving power and converting it into three-phase alternating current power (S220, S230).
As described above, according to an electric vehicle and a driving method thereof in accordance with embodiments of the present disclosure, it may be possible to drive an electric vehicle using a drive inverter and coils within a three-phase motor, and charge a battery using them as a charging device. According to the present disclosure, switching elements within the coil and inverter included in a motor control device can be used, and the use of the inductor and switching elements required for the charging device can be reduced.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2011-0034344 | Apr 2011 | KR | national |
