The present invention relates to a phase detecting device of coil current used when a brushless DC motor and the like used in, for example, an air-conditioner, a water heater having a combustion fan motor, an air purifier, and an information technology device such as a copying machine and a printer are driven, and a motor drive device having same.
As a conventional drive scheme of a brushless DC motor (to be referred to as a “motor” hereinafter), a rectangular wave drive scheme that drives a drive voltage supplied to a drive coil of the motor with a rectangular waveform has been popularly employed.
However, in recent years, demand for a motor driven with a less torque ripple, less noise, and less vibration has increased. As a drive technique corresponding to the demand, a sinusoidal-wave drive scheme that drives a drive voltage supplied to a drive coil of a motor with an almost sinusoidal waveform has been commonly used.
As a conventional technique that drives a motor by the sinusoidal-wave drive scheme, sinusoidal waveform data stored in a memory depending on rotational positions of a motor are sequentially read. The read waveform data are subjected to pulse width modulation (PWM: Pulse Width Modulation). Switching elements constituting a power distributor that supplies electric power to the drive coil of the motor are controlled by PWM to sinusoidal-wave-drive the motor (refer to PTL 1, for example).
A conventional motor drive device will be described below with reference to
As shown in
A circuit operation of conventional motor drive device 100 will be described below in detail.
The position information of rotor 121 of the motor is detected by a plurality of position detecting elements 131 configured by hall elements and the like and position detector 190. Detected position information Hu of rotor 121 is outputted from position detector 190 and inputted to waveform generator 180. In accordance with position information Hu of rotor 121, waveform generator 180 outputs, to power distributor 150, PWM signals UH0, VH0, WH0, UL0, VL0, and WL0 that are set in advance such that voltage differences between the drive coils are almost sinusoidal waves.
Switching elements 151, 152, 153, 154, 155, and 156 in power distributor 150 are on/off-controlled by PWM signals UH0, VH0, WH0, UL0, VL0, and WL0 outputted from waveform generator 180. In this manner, drive voltages Vu, Vv, and Vw and drive currents Iu, Iv, and Iw are supplied from DC power supply 141 to drive coils 101, 103, and 105. At this time, common current Idc flowing from power distributor 150 to DC power supply 141 is detected with current detector 161 including, for example, a resistor or the like. Common current Idc detected with current detector 161 is used when designation is performed such that waveform generator 180 outputs (not shown) a signal that turns off all the switching elements of power distributor 150, for example, when common current Idc excessively increases to control the motor.
However, conventional motor drive device 100, as will be described below, has a problem in which a motor cannot be efficiently driven.
More specifically, in order to efficiently drive the motor, a phase of a drive current flowing in the drive coil of the motor and a phase of an induced voltage induced to the drive coil of the motor must be caused to coincide with each other. At this time, the drive current flowing in the drive coil of the motor has a value obtained by dividing a voltage obtained by subtracting the induced voltage from a drive voltage applied to the drive coil by an impedance of the drive coil. For this reason, the phase of the drive current flowing in the drive coil of the motor always changes depending on a rotating speed of the motor and magnitudes of the drive current and the drive voltage with respect to rotor 121 of the motor.
However, conventional motor drive device 100 does not have a configuration that obtains information of the phase of the drive current flowing in the drive coil of the motor. Thus, a drive voltage waveform to the position of rotor 121 of the motor is uniquely determined. For this reason, the motor cannot be efficiently driven by causing the phase of the drive current that always changes and flows in the drive coil of the motor and the phase of the induced voltage induced to the drive coil of the motor to coincide with each other.
PLT 1: Japanese Patent No. 3232467
The present invention is directed to a motor current phase detecting device that drives a motor having drive coils, the device including a power distributor that supplies a drive voltage and a drive current to each of the drive coils, a current detector that detects a common current waveform flowing from the power distributor, a position detector that detects a position of a rotor, a waveform generator that generates a first PWM signal, a waveform regulator that generates a second PWM signal based on the first PWM signal, and a current phase detector that detects a phase of a drive current flowing in each of the drive coils. The waveform regulator generates the second PWM signal that operates a current phase detector while maintaining a relative voltage value between the drive coils determined by the first PWM signal, and the current phase detector detects the phase of the drive current of the drive coil by detecting a peak current value of the drive coil included in the common current waveform based on the second PWM signal.
In this manner, the phase of the drive current flowing in the drive coil of the motor can be detected with a simple configuration. As a result, the motor can be efficiently driven by causing the phase of the drive current flowing in the drive coil of the motor and the phase of the induced voltage induced to the drive coil of the motor to coincide with each other.
A motor current phase detecting device according to an exemplary embodiment of the present invention will be described below with reference to the accompanying drawings. The present invention is not limited to the embodiment.
As shown in
A circuit configuration of a motor drive device including the motor current phase detecting device according to the exemplary embodiment of the present invention will be described below.
A position of rotor 21 of the motor is detected by a plurality of position detecting elements 31 including, for example, hall elements or the like. The detected position of rotor 21 is outputted from position detecting elements 31 to position detector 90 and inputted to waveform generator 80 as position information Hu. In accordance with position information Hu of rotor 21, waveform generator 80 outputs, to waveform regulator 70, first PWM signals UH0, VH0, WH0, UL0, VL0, and WL0 that are set in advance such that voltage differences between drive coils are almost sinusoidal waves (including sinusoidal waves).
Waveform regulator 70 regulates pulse widths and generation timings of first PWM signals UH0, VH0, WH0, UL0, VL0, and WL0 inputted from waveform generator 80 while maintaining relative voltage values between the drive coils (U phase-V phase, V phase-W phase, and W phase-U phase) to output second PWM signals UH, VH, WH, UL, VL, and WL. Second PWM signals UH, VH, WH, UL, VL, and WL regulated with waveform regulator 70 are outputted to power distributor 50 and current phase detector 60.
Switching elements 51, 52, 53, 54, 55, and 56 in power distributor 50 are on/off-controlled with second PWM signals UH, VH, WH, UL, VL, and WL outputted from waveform regulator 70. In this manner, drive voltages Vu, Vv, and Vw and drive currents Iu, Iv, and Iw are supplied from DC power supply 41 to drive coils 1, 3, and 5 through power distributor 50, respectively. At this time, common current Idc flowing from power distributor 50 to DC power supply 41 is detected with current detector 61 including, for example, a resistor or the like. Detected common current Idc is inputted to current phase detector 60 as common current waveform Rdc.
Current phase detector 60 detects phases of drive currents Iu, Iv, and Iw flowing in drive coils 1, 3, and 5 based on common current waveform Rdc inputted from current detector 61 and second PWM signals UH, VH, WH, UL, VL, and WL inputted from waveform regulator 70. Current phase detector 60 outputs phase information PD of detected drive currents Iu, Iv, and Iw of drive coils 1, 3, and 5 to waveform generator 80.
Waveform generator 80 controls the first PWM signals based on phase information PD inputted from current phase detector 60 and position information Hu inputted from position detector 90. The phase of the drive current flowing in the drive coil of the motor and the phase of the induced voltage induced by the drive coil of the motor are caused to coincide with each other based on the second PWM signal obtained by regulating the first PWM signal with waveform regulator 70 so as to drive the motor.
As described above, the motor drive device including the motor current phase detecting device according to the exemplary embodiment of the present invention is configured.
An operation of the motor current phase detecting device configured as described above will be described below with reference to
That is,
As shown in
Phase detection of the motor current phase detecting device according to the exemplary embodiment of the present invention will be described below with reference to
The following explanation is made on the assumption that the switching element is turned on when pulse waveforms of the first PWM signal and the second PWM signal are High and the switching element is turned off when the pulse waveforms are Low.
That is,
When drive voltages Vu, Vv, and Vw of drive coils 1, 3, and 5 of the motor have waveforms as shown in
Thus, common current waveform Rdc including the pieces of waveform information of drive currents Iu, Iv, and Iw will be described below with reference to
That is, as shown in
In section b, switching element 56 below only the W phase of power distributor 50 is turned on, and switching elements 52 and 54 below the other phases are turned off. For this reason, in common current waveform Rdc, as RdcA, the peak current value of drive current Iw flowing in W-phase drive coil 5 is detected as a waveform the polarity of which is inverted. This is because a flowing direction of drive current Iw is opposite to the arrow in the drawing. At this time, switching element 55 above the W phase of power distributor 50 is turned off, and switching element 51 and 53 above the other phases are turned on.
Thus, it is understood that common current waveform Rdc includes pieces of information of drive currents Iv and Iw of two phases, i.e., a V phase and a W phase as peak current values.
In this case, in a motor having three-phase drive coils, a total of drive currents Iu, Iv, and Iw flowing in three-phase drive coils 1, 3, and 5 is zero. For this reason, as described above, when pieces of information of drive currents of two phases, for example, the V phase and the W phase can be obtained, a drive current of the U phase serving as one remaining phase can be easily estimated.
Thus, by using common current waveform Rdc detected with current detector 61, current phase detector 60 can generate phase information PD of a drive current of a drive coil.
Phase information PD of the drive current of the drive coil generated by current phase detector 60 will be concretely described below.
Current phase detector 60 detect, for example, section a or section b in
As shown in
Based on the first PWM signal of waveform generator 80, waveform regulator 70 that regulates a pulse width and a generation timing to generate a second PWM signal will be described below with reference to
At this time, as shown in
However, when magnitude information of common current waveform Rdc is detected, the pulse width of the first PWM signal is preferably wide. This is because, since the pulse width of the first PWM signal becomes narrow near a zero level of the first PWM signal, a change in peak current value of common current waveform Rdc may not be able to be detected at a normal timing. Furthermore, for example, response of the switching element of power distributor 50 configured by a MOS (Metal Oxide Semiconductor) or the like is too late, and common current waveform Rdc may not be outputted.
Waveform regulator 70 regulates the pulse widths and the generation timings of first PWM signals UH0, UH0, WH0, UL0, VL0, and WL0 inputted from waveform generator 80 and being in a narrow-pulse-width section. More specifically, as shown by the second PWM signals in the lower half of
A method of detecting phase information by using a drive voltage outputted from power distributor 50 by the second PWM signals regulated with waveform regulator 70 will be described below with reference to
As shown in
Current phase detector 60 generates, based on the regulated second PWM signal, phase information PD of the drive current of the drive coil by pieces of magnitude information of RdcA and RdcB that are peak current values of the drive currents of the drive coils detected from common current waveform Rdc. Generated phase information PD of the drive currents of the drive coils is inputted to waveform generator 80.
Waveform generator 80 regulates phases to obtain a drive voltage waveform that causes a phase of a drive current flowing in the drive coil to coincide with a phase of an induced voltage induced in the drive coil based on inputted phase information PD and position information Hu of the rotor of the motor to output a first PWM signal. In this case, the phase information of the induced voltage is detected based on position information Hu of the rotor.
The pulse width and the generation timing of the first PWM signal outputted from waveform generator 80 are regulated with waveform regulator 70 to generate a second PWM signal, and the motor is driven through power distributor 50.
According to the exemplary embodiment, the phase information of the drive current can be detected in a simple circuit configuration in which the phase information of the drive current is detected by a current phase detector from the peak current value of common current waveform Rdc detected by the current detector. In this manner, the motor can be driven such that the phase of the drive current flowing in the drive coil of the motor and the phase of the induced voltage induced by the drive coil are caused to coincide with each other. As a result, a motor drive device that can efficiently drive the motor and drives the motor with small noise and small vibration can be realized.
According to the exemplary embodiment, the waveform regulator is arranged to prevent a detection mistake occurring when a pulse width is narrow or an output mistake caused by a response speed of a switching element so as to make it possible to reliably detect phase information. As a result, a high-efficiency motor drive device having high controllability and high reliability can be realized.
The motor current phase detecting device according to the exemplary embodiment is combined to a motor to make it possible to realize a motor drive device that can efficiently drive the motor with small noise and small vibration.
The present invention is useful for fan drive of a motor for air-conditioning equipment required to be efficiently driven with small vibration and low noise or drive of a motor used in a home electric appliance such as an air purifier, a refrigerator, a washing machine, a water heater having a combustion fan motor; or a printer, a copying machine, scanner, a facsimile, or a complex machine thereof; or an information technology device such as a hard disk drive or an optical medium device.
1, 3, 5, 101, 103, 105 drive coil
10, motor current phase detecting device
21, 121 rotor
31, 131 position detecting element
41, 141 DC power supply
50, 150 power distributor
51, 52, 53, 54, 55, 56, 151, 153, 155, 152, 154, 156 switching element
60 current phase detector
61, 161 current detector
70 waveform regulator
80, 180 waveform generator
90, 190 position detector
100 motor drive device
Number | Date | Country | Kind |
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2010-206303 | Sep 2010 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2011/004975 | 9/6/2011 | WO | 00 | 2/22/2013 |