JPH06327286A - Motor driving equipment - Google Patents

Abstract

PURPOSE:To make it possible to reduce torque ripples in commutation by gradually increasing the current in the two-phase energized section of an inverter. CONSTITUTION:A corrector 108 corrects a duty factor (ratio of time period for which voltage is applied to a winding) DTO so that the current is inclined, and thereby obtains a duty factor DT. A modulator 105 modulates drive signals of an inverter 101 according to the duty factor DT to produce pulse width modulation signal PD output. A drive circuit 106 generates drive signals DV to drive the switching element of the inverter 101 according to the pulse width modulation signal PD. The inverter 101 performs chopper operation according to the drive signals DV to adjust and control the current fed to a motor 103 so that the motor 103 is run at a commanded number of revolutions NR. This reduces torque ripples that occur in commutation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device for an electric motor, and more particularly, it converts a direct current power supply into an alternating current, and one phase of this alternating current has a pause section in which no flow is conducted, and a PWM pulse modulation is provided in the flow section. The present invention relates to a motor drive device that uses a 120-degree conduction inverter that is modulated by a signal to perform variable speed operation.

[0002]

2. Description of the Related Art In a conventional 120-degree conduction type inverter device, as described in JP-A-62-171489, at the time of commutation for switching the conduction phase of a winding, the conduction of the phase which has been flowing until then is conducted. Before stopping, the energization of the next phase is started, and then the energization of the phase that has been flowing until then is terminated, and a three-phase energization mode is added.

[0003]

The above-mentioned prior art is intended to reduce the torque ripple generated during commutation due to the effect that the current increases due to the three-phase energization. However, since the increase of the current is only during the three-phase conduction state, the amount of increase of the current is adjusted by the time adjustment of the three-phase conduction mode, and the current is locally increased. For this reason, if the three-phase energization time is too long, the local current may increase excessively and the time change rate of the current proportional to the motor torque may increase.

Further, there is a non-linear relationship between the time of the three-phase energization mode and the amount of current rise, and it is difficult to predict the relationship between the magnitude of torque fluctuation and the time of the three-phase energization mode. .

An object of the present invention is to suppress the increase in the rate of change of the current with time, reduce the torque ripple generated during commutation, and further reduce the torque ripple generated during commutation even when the load or the motor speed changes. An object is to provide a reduced electric motor drive device.

Another object of the present invention is to reduce the vibration and noise generated by the resonance of the tub by using the electric motor drive device as a drive device for a washing tub or a dehydration tub of a washing machine.

[0007]

In order to solve the above-mentioned problems, the present invention is based on a control signal from a control device, in which a one-phase output from a DC power source is a constant energization suspension period during an electrical angle of 180 degrees. In a motor drive device that drives a motor at a variable speed by a 120-degree conduction type inverter that obtains an AC output of three or more phases, the control device increases a current in a two-phase conduction section of the inverter. I was prepared.

Further, in the above-mentioned structure, a current detecting means for detecting a current and an inclination amount commanding means for designating an inclination amount of the current in the commutation cycle are provided, and the inclination of the current detection value detected by the current detecting means is A correction amount correction unit that corrects the correction amount according to the difference in the tilt amount output by the tilt amount instruction unit, or a correction amount correction unit that corrects the correction amount according to the detected motor rotation speed or motor load is provided. ing.

Further, the above-mentioned electric motor drive device is used in a rotary drive constituent part of a washing tub or a dewatering tub of a washing machine.

[0010]

In the motor drive device of the present invention configured as described above, the current immediately before the commutation is continuously increased from the current flowing by correcting the current ratio, and the time of the torque generated during the commutation is increased. By reducing the rate of change, torque ripple that occurs during commutation can be reduced.

Furthermore, by changing the amount of increasing the current in accordance with the detected motor speed and load, it is possible to always perform commutation with an optimum current value even when the motor speed and load change, so that operating conditions can be improved. It is possible to reduce the torque ripple during commutation accordingly.

Further, by performing the variable speed operation of the washing machine by using the electric motor drive device capable of low torque ripple operation regardless of the electric motor speed and load, continuous variable speed operation is avoided without avoiding a mechanical resonance point. Driving can be realized.

[0013]

Embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 is a block diagram of an electric motor drive device according to an embodiment of the present invention. The electric motor drive device according to the present invention is
Power is supplied from the DC power supply 102 to the brushless DC motor 103 via the 120-degree conduction type inverter 101. The motor speed N is detected by the speed detecting means 109,
The flow ratio DT0 is determined by the flow ratio generator 104 so that the error becomes zero by comparing with the speed command NR output from the speed command device 107. Here, the conduction ratio DT0 is given by DT0 = Ton / T, where T is the period of the pulse width modulation signal and Ton is the time during which the voltage is applied to the winding. Hereinafter, the conduction ratio refers to the ratio of the voltage application time to this winding. The correction device 108 creates a conduction ratio DT by correcting the conduction ratio DT0 so that the current is inclined. The modulator 105 modulates the drive signal of the inverter with the duty ratio DT and outputs the pulse width modulation signal PD, and the drive circuit 106 drives the switching element of the inverter by the drive circuit 106 according to the pulse width modulation signal PD. To occur. The inverter 101 performs a chopper operation by the drive signal DV to adjust the current flowing through the electric motor, and controls the electric motor to rotate at the command speed NR.

Each element will be described in more detail below.

The 120-degree conduction type inverter 101 comprises three-phase windings 1Ia to 1I of the brushless DC motor 103 by means of switching elements T1 to T6 and diodes D1 to D6.
connected to c. The switching elements T1, T2 and T3 have their motor windings connected to the positive side terminal of the DC power source 102, and by turning them on, a positive voltage is applied to the motor windings. Switching elements T4, T5 and T
A motor winding 6 is connected to the negative side terminal of the DC power source 102, and by turning on these terminals, a negative voltage is applied to the motor winding.

The drive circuit 106 outputs six drive signals DV which are control signals for turning on / off these switching elements.

The speed detecting means 109 detects and outputs the speed N of the electric motor. As the speed detecting means 109, a Hall sensor is used to detect the magnetic pole position of the electric motor, and the speed is detected from this magnetic pole position, or the counter electromotive force generated in the motor winding is detected. Can be used.

The speed command device 107 outputs a speed command NR which is the speed at which the electric motor should rotate.

The flow rate generator 104 uses the speed command NR.
So that the difference between the motor speed and the detected speed N becomes zero.
Decide 0 and output. That is, when the speed N is larger than the speed command NR, the flow rate is reduced, and conversely, the speed N is the speed command N.
When it is smaller than R, the flow rate is increased to adjust the average torque of the electric motor to perform acceleration / deceleration to control the speed.

As will be described later, the correction device 108 corrects the flow rate DT0 by inclining the winding current so that it becomes larger with respect to the average current, and creates the flow rate DT. The modulator 105 creates and outputs a pulse width modulation signal PD according to the conduction ratio DT.

The drive circuit 106 outputs a pulse width modulation signal P
A drive signal DV for turning on / off the switching elements T1 to T6 of the inverter is created according to D, and the average torque is controlled by adjusting the voltage applied to the three phases 1Ia, 1Ib, 1Ic of the electric motor according to this signal. Realize speed control by.

FIG. 2 is a diagram for explaining the operation in one embodiment of the present invention, showing the three-phase winding currents (Ia, Ib, Ic) and the torque component current (IT). The torque component current IT is the sum of the absolute values of the currents flowing in the three phases of the electric motor, and in the electric motor driven by the 120-degree conduction type inverter, torque is generated near the peak of the back electromotive force of the electric motor. The counter electromotive force during current flow is relatively flat, and the motor torque is approximately proportional to the torque current. In one embodiment of the present invention, the correction unit 108 corrects the conduction ratio so that the torque current IT has an inclination within an electrical angle of 60 degrees (T60 section) in which the same torque is energized with respect to the average torque. Add.

FIG. 3 is a diagram for explaining the operation in the prior art. Like FIG. 2, three-phase winding currents (Ia, I) are shown.
b, Ic) and the torque component current (IT). The figure shows the case where the constant current control is applied so that the torque current IT becomes flat within the electrical angle of 60 degrees (T60 section) in which the two phases are energized. In this case, the torque component current becomes flat in the T60 section, but after the commutation, the torque component current IT transiently changes suddenly (circle in the figure). The magnitude of the abrupt change of the torque current IT depends on the motor load torque and speed, but tends to increase as the load torque and speed increase.

FIG. 4 is an operation explanatory view in one embodiment of the present invention, which is shown in comparison with the prior art. The section (a) shows the operation of the present invention, and the section (b) shows the operation of the constant current control shown in FIG. Also 1 in each column
The two-phase winding currents that switch at the time of commutation are overlapped and shown in the stage, and the motor torque and average torque that are almost determined by the torque component current IT are shown in the second stage and the magnitude of vibration of the motor in the third stage. In order to compare the above, the differentiation of the torque current is shown. It should be noted that this differential value indicates an envelope change excluding the change due to pulse width modulation.

In the present invention, the time (recirculation time) t1 until the reflux current Ir (current goes toward zero) of the phase that has finished flowing becomes zero and the rising current Iu of the phase that newly starts flowing are averaged. The conduction ratio D is set so that the currents within the electrical angle of 60 degrees are inclined so that the rising times t2 to reach the current values are equal.
Add a correction to T0.

On the other hand, in the conventional constant current control, as shown in column (b), the conduction ratio is changed so that the winding current matches the average current and becomes substantially constant, and the average torque is flattened. Control so that In this case, load torque
As the speed increases, the recirculation time t1 becomes shorter than the rising time t2 as a result, and the time difference causes a drop in the motor torque as shown in the second stage.

Next, comparing the differentiated motor torques, in the constant current control, a large torque change as shown in the figure occurs during commutation, and vibration and noise are generated due to the large torque change. In the present invention, a slight torque increase occurs within an electrical angle of 60 degrees, but the size is small and very slow, and the torque change occurring during commutation can be suppressed to a small level.

FIG. 5 shows a correction method in one embodiment of the present invention. The broken line shown in the figure is the flow rate generator 104.
Is the conduction ratio DT0 determined by
It is the flow rate DT corrected by 108. In these figures, the vertical axis shows the flow rate and the horizontal axis shows the time, and shows how the electrical angle changes during the time T60 of 60 degrees. Although six types of correction methods (a) to (f) are shown in the figure, the correction method may be selected according to the characteristics of the electric motor, the speed control range, and the like. The magnitude of the correction may be another method as long as it is determined so that the winding current immediately before the commutation becomes the return time t1 = the rise time t2 as shown in the column (a) of FIG.

To determine the correction amount, the operating characteristic of the motor is measured in advance to obtain the correction amount such that the circulation time t1 = rise time t2 as shown in the column (a) of FIG. With such a configuration, it is possible to reduce torque ripple during commutation.

Next, another embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG.

FIG. 6 is a block diagram of an electric motor drive device according to another embodiment of the present invention. The same reference numerals as in FIG. 1 represent the same parts.

In this embodiment, a detection resistor 201 for detecting the direct current supplied to the electric motor through the inverter and a correction amount setting device 202 for determining the correction amount from the detected current value Id detected by the detection resistor 201 are used. Detection resistor 201
The current detected at is the winding current of the motor excluding the return current flowing through the diodes D1 to D6, and the winding current may or may not be visible depending on the on / off state of the switching element. Correction amount setting device 202
Among these, the magnitude of the winding current is detected by using the state in which the winding current is visible, and the correction amount D of the current immediately before commutation described later
The conduction ratio correction amount DDT is determined so as to realize Id.
As a result, feedback is provided by current detection, and the duty factor correction amount can be changed according to changes in the motor operating state (load torque, speed, etc.), and correction can be made according to load fluctuations and speed fluctuations. become.

The operation of the correction amount setting device 202 will be described below with reference to FIGS.

FIG. 7 is a conceptual diagram of commutation, and FIG. 7A schematically shows the waveform of the winding current shown in the first stage of FIG. Further, FIG. 7B shows the torque component current IT
Is shown. The rising current Iu rises fastest during commutation and the rising time t2 is minimized when the conduction ratio is 1 during this period, and FIG. 7 shows the current waveform in this case. Now, let Im be the average current of the currents flowing before and after commutation, and perform the commutation at time t0 until the reflux current Ir becomes zero, the reflux time t1, and the rising current Iu is Im.
Let rise time t2 be the time required to reach t. At this time, the winding resistance R, the winding inductance L of the electric motor, the applied voltage E1 <0 (corresponding to the difference between the applied DC voltage and the back electromotive force) applied to the phase in which the flow has ended, and the flow of current The applied voltage E2> 0 (corresponding to the difference between the applied DC voltage and the back electromotive force) applied to the phase in which the start is applied is a positive voltage applied to one of the three phases and a negative voltage applied to the remaining two phases. It is given by the following equation from the three-phase flow model.

[0036]

[Equation 1]

[0037]

[Equation 2]

FIG. 8 is a diagram for explaining the operation according to another embodiment of the present invention, showing the relationship between the magnitude of the current derived from these and the reflux time t1 and the rise time t2.
From this, when the average current of the current flowing before and after the commutation is set to Im constant, the state of FIG. 4 is realized only at the point where the magnitude of the current is I0, and the low torque ripple at the commutation is realized. Although it can be done, if the current value changes, t2> t1 and FIG.
(B) A drop in the motor torque shown in column -2 occurs. On the contrary, when t2 <t1, the torque ripple can be reduced by the current control such that the conduction ratio is <1.

FIG. 9 shows the lift amount in the correction amount setting device of the present invention. In FIG. 9A, the drop amount DI and the lift amount DId are shown with respect to the motor current.

FIG. 10 conceptually shows the shape of the current in the winding current waveform in the embodiment of the present invention, and the current pulsation due to the pulse width modulation is omitted. When the magnitude of the current becomes larger than that in FIG. 9A, the dip amount DI increases in the constant current control (when the average current of the currents flowing before and after the commutation is constant Im), which increases the dip during the commutation. A sudden change in torque will occur. FIG. 9B shows the lift amount DId necessary for the drop amount ID = 0, which shows the difference between the average current Im and the current before commutation as shown in FIG. The correction amount setting device 202 in the embodiment of the present invention determines the lift amount DId based on FIG. 9B, and determines the conduction ratio correction amount DDT so that the detected current value Id has the shape shown in FIG. . Actually, the lift amount DId is a number 1
And the difference between the average current value Im1 (the average current obtained from the equation 1) and the average current value Im2 (the average current obtained from the equation 2) at which t1 = t2 in the equation 2 are obtained. The flow rate correction amount DDT is determined so as to realize the obtained lift amount.
In general, from Equations 1 and 2, DId> ID.

In the present embodiment, the supplied power that changes according to the magnitude of the load torque (almost the detected current value I when the DC voltage is constant).
(proportional to d) can be detected and the torque ripple can be reduced accordingly.

Next, another embodiment of the present invention will be described with reference to FIG.
And it demonstrates using FIG.

FIG. 11 is a block diagram of an electric motor drive device according to another embodiment of the present invention. The same reference numerals as in FIG. 1 represent the same parts.

In this embodiment, the correction amount setting device 302 for determining the conduction ratio correction amount DDT3 according to the speed N is used. The operation of the correction amount setting device 302 will be described below with reference to FIG.

FIG. 12 shows the lift amount in the correction amount setting device of the present invention. The drop amount DI shown in FIG.
And the change of the required amount of lift DId with respect to the speed change is shown. As is clear from the figure, when the rotation speed changes, the back electromotive force changes, which leads to
The change in E1 and E2 in the equation 2 changes the amount of depression DI and the required amount of lift DId. The correction amount setting device 302 determines the lift amount DId according to the relationship shown in FIG. 12B, and determines the conduction ratio correction amount DDT3 so that the detected current value Id has the shape shown in FIG.
In reality, the lifting amount DId is t1 in the equations 1 and 2.
= T2 and the average current value Im1 (the average current obtained from Equation 1) and the average current value Im2 (the average current obtained from Equation 2) are obtained, and the amount of lifting obtained from this is obtained by current feedback. The flow rate correction amount DDT3 is determined so as to be realized.

FIG. 13 shows another embodiment of the present invention.
And it demonstrates using FIG.

FIG. 13 is a block diagram of an electric motor drive device according to another embodiment of the present invention. 1 to 12 represent the same parts.

In this embodiment, the detected current value I of the motor windings 1Ia, 1Ib, 1Ic is used instead of the detected DC current value shown in FIG.
A correction amount setting device 402 that determines the conduction ratio correction amount DDT4 using a, Ib, and Ic is used. The operation of the correction amount setting device 402 will be described below with reference to FIG.

FIG. 14 is an explanatory diagram of the operation in one embodiment of the present invention. The figure shows the winding currents of the three phases, a-phase, b-phase, and c-phase, when switching from the state of flowing from a-phase to c-phase by commutation to the state of flowing from b-phase to c-phase. ing. Further, regarding the circulation time t1 and the rising time t2, t1
> T2, t1 = t2, t1 <t2 are shown.

The non-switching phase of the flow (in this case c
The current of (phase) shows a characteristic shape in the relationship between t1 and t2. When t1 <t2, the amount of drop DI1 occurs when the c-phase current is commutated. On the contrary, when t1> t2, the c-phase current has a very large lift amount and DId1 is generated. From this fact, when the three-phase current is detected, the current waveform of the phase in which the current does not switch due to commutation (here, the c-phase) is detected, and the lift amount DI0 is determined so that the dip amount DI1 becomes zero. Good. As described above, the correction amount setting device 402 according to the present embodiment determines the lift amount DId0 so that the current drop amount DI1 of the phase that does not switch the commutation during the commutation becomes zero, and the current detection value immediately before the commutation becomes The conduction ratio correction amount DDT4 is determined so that the lift amount DId0 becomes larger than the average current. Actually, the flow rate correction amount D
The lift amount DId0 is determined by feedback control by repeatedly detecting the drop amount DI1 when the DT4 is changed and recorrecting the conduction ratio correction amount DDT4 so that the drop amount becomes zero.

In the present embodiment, the correction amount setting device can directly detect the reflux current t1 by detecting the reflux current Ir. Therefore, the detected reflux time t1 and the rise time t2 at which the current rises to the average value can be obtained. The lift amount DId0 may be determined by measurement so that they match.

In this embodiment, the overlap time at the time of commutation can be automatically adjusted from the detected value of the winding current, so that the low torque ripple control can be automatically realized regardless of the characteristics of the motor.

FIG. 15 shows another embodiment of the present invention.
Will be explained.

FIG. 15 is a block diagram of an electric motor drive device according to another embodiment of the present invention. 1 to 12 represent the same parts.

In the present embodiment, the speed control device 501 outputs the current command IR so that the difference between the detected speed N and the speed command NR becomes zero, and the current control device 502 flows in the same phase. The current flow rate DT is determined so that the detected current value Id rises with respect to the current command IR by the lift amount DId shown in the above-described embodiments within the cycle. As a result, the current control device 502 automatically adjusts the lifting amount without knowing the relationship between the change in the conduction ratio and the change in the current lifting amount, so that the lifting amount DId according to the speed and the magnitude of the load.
Only the information can realize low torque ripple control.

Next, a system to which the motor drive device of the present invention is applied will be described with reference to FIG.

FIG. 16 is a block diagram of a washing machine according to another embodiment of the present invention. In this embodiment, the operation control device 90
4 is a weight sensor 902 provided under the washing tub 905.
Detects the amount of laundry put in the washing tub and operates the washing machine at a variable speed according to this amount. That is, the operation is performed while changing the speed command Ns according to the amount of laundry. The motor drive device 901 adjusts the brushless DC motor 10 so as to match the speed command output from the operation control device 904.
3 speed control. In this embodiment, in addition to the variable speed operation at the time of washing, even when the rotation speed at the time of dehydration is continuously changed,
It is possible to realize low vibration and low noise operation by automatically adjusting the current waveform so that the torque ripple is always reduced according to the number of revolutions of the electric motor and the size of the load. Particularly, in the washing machine, since the washing tub plays the role of a loudspeaker, a large amount of noise has been generated in the past even with a slight vibration, but the present invention has remarkably reduced the noise.

[0058]

According to the present invention, according to the commutation characteristics of the inverter, the commutation rate is continuously increased from during the commutation of the current immediately before the commutation, and the time change rate of the torque generated during the commutation is increased. The effect of reducing torque ripple is to reduce the torque ripple that occurs during commutation.

Further, according to the present invention, by performing the variable speed operation of the washing machine by using the electric motor drive device which always reduces the torque ripple at the time of commutation regardless of the electric motor rotation speed and the magnitude of the load, it is possible to perform the dehydration. There is an effect of realizing continuous low-noise variable speed operation without avoiding mechanical resonance points before reaching high speed rotation such as.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an electric motor drive device according to an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram in one embodiment of the present invention.

FIG. 3 is an operation explanatory diagram in the conventional technique.

FIG. 4 is an operation explanatory diagram according to the embodiment of the present invention.

FIG. 5 is a correction method according to an embodiment of the present invention.

FIG. 6 is a configuration diagram of an electric motor drive device according to another embodiment of the present invention.

FIG. 7 is a conceptual diagram of commutation in a 120-degree conduction type inverter.

FIG. 8 is an operation explanatory diagram according to another embodiment of the present invention.

FIG. 9 is a lift amount according to another embodiment of the present invention.

FIG. 10 is a current waveform according to another embodiment of the present invention.

FIG. 11 is a configuration diagram of an electric motor drive device according to another embodiment of the present invention.

FIG. 12 is a lift amount according to another embodiment of the present invention.

FIG. 13 is a configuration diagram of an electric motor drive device according to another embodiment of the present invention.

FIG. 14 is an explanatory diagram of the operation in another embodiment of the present invention.

FIG. 15 is a configuration diagram of an electric motor drive device according to another embodiment of the present invention.

FIG. 16 is a configuration diagram of a washing machine according to another embodiment of the present invention.

[Explanation of symbols]

101 ... Inverter, 102 ... DC power supply, 103 ... Brushless DC motor, 104 ... Commutation rate generator, 105 ...
Modulator, 106 ... Drive circuit, 107 ... Speed command device, 108, 208 ... Correction device, 109 ... Speed detection means.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naoki Yamamoto 5-20-1 Kamimizumoto-cho, Kodaira-shi, Tokyo Inside the Semiconductor Division, Hitachi, Ltd. No. 1-1 Living Equipment Division, Hitachi, Ltd. (72) Inventor, Kazuyoshi Matsuo 1-1-1, Higashi-Tagacho, Hitachi City, Ibaraki Prefecture Living Equipment Division, Hitachi, Ltd.

Claims (12)

[Claims] 1. A 120-degree conduction type inverter that obtains an AC output of three or more phases having a constant conduction interruption section during an electrical angle of 180 degrees based on a control signal from a control device for the output of one phase from a DC power source. In the electric motor drive device for driving the electric motor at a variable speed, the control device includes a current sloping means for increasing a current in a two-phase energization section of the inverter. 2. The current sloping means according to claim 1, wherein the current sloping means is a conduction ratio for controlling a magnitude of an output current of the inverter, and a command value thereof increases in a rising manner over a two-phase section of the inverter. An electric motor drive device characterized in that it is configured by means for imparting various inclinations. 3. The control device according to claim 1, wherein the control device uses a pulse width modulation signal obtained by comparing a duty ratio command for commanding an output current of the inverter and a carrier as the control signal. The motor driving device, wherein the inclining means is constituted by means for increasing the frequency of the carrier wave in a rising manner over the two-phase section of the inverter. 4. The means for outputting a command value signal for the rotational speed of the electric motor, the means for detecting the rotational speed of the electric motor, and outputting the signal for the detected value according to claim 2, Means for generating a command value of the flow rate based on each signal of the command value and the detection value,
A motor drive device, comprising: a correction unit that corrects the flow rate command value by inclining the two-phase section of the inverter so as to increase upward. 5. The correction means according to claim 4, wherein the correction means corrects the flow rate command value from any signal from a means for outputting a command value or a detected value of the rotation speed of the electric motor. An electric motor drive device characterized in that 6. The load amount detecting means according to claim 4, which detects a magnitude of a load driven by the electric motor and outputs a signal thereof, wherein the correcting means receives the signal from the load amount detecting means. A motor drive device characterized in that a flow rate command value is corrected. 7. The motor drive device according to claim 6, wherein the load amount detecting means is a current detecting means that detects an input current or an output current of the inverter and outputs a signal thereof. 8. The motor drive device according to claim 4, wherein the correction unit has a current flow rate during a cycle in which a current flow rate at the end of a cycle in which a current is flowing between the same two phases. A motor drive device, characterized in that correction is performed so as to be larger than a minimum value of the ratio. 9. The electric motor drive device according to claim 4, further comprising a current detection unit that detects a current of a winding of each phase of the electric motor, and switches the flow state detected by the current detection unit. An electric motor drive device comprising means for correcting the conduction ratio so as to reduce the amount of drop in the detected value of the phase current whose commutation state does not change during commutation. 10. The motor drive device according to claim 1, wherein the inverter is P modulated by a pulse width modulation signal.
In the WM inverter, an electric motor driven by the inverter, a speed detecting means for detecting the speed of the electric motor, a speed command means for setting the speed of the electric motor, a speed detected by the speed detecting means and the speed command means The speed control means for outputting the current command of the inverter according to the difference in the commanded speed and the current detection means for detecting the current are the same as the current command output by the speed control means. A current control means for deciding a current flow rate is provided so that a current command during a period in which a current is flowing between the phases is provided with an inclination, and the inclined current command and the current detected by the current detection means coincide with each other. A motor drive device characterized by: 11. The electric motor drive device according to claim 1, further comprising a clocking means for measuring a reflux time until the reflux current of a phase in which the flow has ended is zero during commutation for switching the flow state of the winding. And a correction means for correcting the flow rate so that the time until the current of the phase at which the current starts to reach the average current value matches the reflux time measured by the time measuring means. Electric motor drive. 12. A washing machine, characterized in that any one of the electric motor drive devices according to any one of claims 1 to 11 is used in a rotary drive component of a washing tub or a dehydration tub.