JP2007159345A - Controller for motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the operation efficiency of a motor from dropping excessively due to the increase of the current ripple of each phase of currents estimated from the detected value of the current on the DC side of an inverter. <P>SOLUTION: A PWM signal generator 24 computes the current duration being the duration of each phase current Iu, Iv, and Iw at a DC link current IDC in single carrier cycle fc, and acquires the minimum current duration from the current duration of every phase current Iu, Iv and Iw. It sets a value, which is obtained by subtracting the duration of the minimum current from the specified time according to the detection stability time required for the actual detection state by a current sensor 14b on DC side to reach its specified stable state, as the phase difference of a three-phase carrier signal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for an electric motor.

Conventionally, for example, an inverter that controls an electric motor by pulse width modulation (PWM) and a current sensor that detects a DC current of the inverter instead of a current sensor that detects each phase current of the electric motor, the DC detected by the current sensor There is known a control device that estimates each phase current of an electric motor from a side current and generates a pulse width modulation signal using a three-phase carrier signal having a predetermined phase difference (see, for example, Patent Document 1).
JP 2004-208413 A

By the way, in the control device according to the above-described prior art, the current of each phase current estimated from the detected value of the DC side current is merely generated by the pulse width modulation signal by the three-phase carrier signal having a predetermined phase difference. If the ripple increases excessively, there is a risk that the operating efficiency of the electric motor will decrease excessively.
The present invention has been made in view of the above circumstances, and prevents an increase in current ripple of each phase current estimated from the detected value of the DC side current of the inverter, thereby preventing the motor operating efficiency from being excessively reduced. It is an object of the present invention to provide an electric motor control device that can be used.

  In order to solve the above-described problems and achieve the object, the motor control device according to the first aspect of the present invention is applied to a multi-phase motor by a pulse width modulation signal (for example, a PWM signal in the embodiment). Of the inverter (for example, the PWM inverter 14A in the embodiment) and current detection means (for example, the DC link current IDC in the embodiment) of the inverter (for example, the DC link current IDC in the embodiment) DC-side current sensor 14b) in the embodiment, and the phase current of the motor based on the DC-side current detected by the current detection means (for example, each phase current Iu, Iv, Iw in the embodiment) Phase current estimation means (for example, phase current estimation unit 25 in the embodiment) for estimating the switching current of the inverter based on the phase current estimated by the phase current estimation means And a control means (for example, the control unit 15 in the embodiment) for performing switching control for controlling the on / off state, wherein the pulse width modulation signal is generated by a carrier signal of a plurality of phases Current width which is the duration of the phase current for each of the plurality of phases in the pulse width modulation signal generation means (for example, the PWM signal generation unit 24 in the embodiment) and the DC current in a single carrier cycle Current duration detection means for detecting time (for example, current duration calculation unit 32 in the embodiment) and the minimum of the current duration for each of the plurality of phases detected by the current duration detection means Phase difference setting means for setting a phase difference of the carrier signal between the plurality of phases based on a value (for example, a phase difference calculation unit 33 in the embodiment). There.

  According to the motor control device configured as described above, for example, the current duration for each phase current detected in accordance with various command values in switching control (that is, for each phase in the DC-side current in a single carrier cycle). Current duration for each phase current in the DC-side current actually detected by the current detection means by setting the phase difference of the carrier signal between multiple phases based on the minimum value of the on-duty duration) It can be set to an appropriate value, for example, if the current duration becomes excessively short, it becomes difficult to detect the phase current, or if the current duration becomes excessively long, for example, the current of the phase current It is possible to prevent the problem that the ripple increases. As a result, even when the output voltage amplitude of each phase is relatively small, such as in a low rotation state where the rotational speed of the motor is relatively low, the phase current is estimated from the direct current. Reliability and estimation accuracy can be improved, and the electric motor can be appropriately controlled.

  Furthermore, in the motor control device according to the second aspect of the present invention, is the minimum value of the current durations for each of the plurality of phases detected by the current duration detection means equal to or greater than a predetermined value? Determination means (for example, step S03 in the embodiment) for determining whether or not, the phase difference setting means, when the determination means determines that the minimum value is less than the predetermined value, A value obtained by subtracting the minimum value from the predetermined value is set as the phase difference, and when the determination unit determines that the minimum value is equal to or greater than the predetermined value, the phase difference is set to zero. It is characterized by.

  According to the motor control device having the above configuration, when the minimum value of the current duration for each of the plurality of phases is less than the predetermined value, for example, each phase current is detected from the DC side current with at least a desired accuracy. Thus, the value obtained by subtracting the minimum value of the current duration from the predetermined value is set as the phase difference of the carrier signal between a plurality of phases. As a result, the pulse width modulation is performed only by a single carrier signal, for example, due to the relatively small output voltage amplitude of each phase, such as in a low rotation state where the rotation speed of the motor is relatively low. Even when there is a risk that the reliability and estimation accuracy when estimating the phase current will be reduced in the state where the signal is generated, the reliability and estimation accuracy when estimating the phase current from the DC side current will be improved. The electric motor can be appropriately controlled. On the other hand, when the minimum value of the current duration for each of the plurality of phases is less than a predetermined value, the phase difference of the carrier signal between the plurality of phases is zero (that is, when a pulse width modulation signal is generated by a single carrier signal) It is possible to detect each phase current from the DC side current with a desired accuracy, for example, compared with the case where a pulse width modulation signal is generated by a carrier signal of a plurality of phases having a phase difference other than zero. Thus, it is possible to prevent the current ripple of the phase current estimated from the DC side current from increasing.

  Further, in the motor control device according to the third aspect of the present invention, the predetermined value is set based on a detection stabilization time required for the detection state by the current detection means to reach a predetermined stable state. Means (for example, step S03 in the embodiment) is provided.

  According to the motor control apparatus having the above-described configuration, a predetermined value that is a determination threshold value corresponding to the minimum value of the current duration for each of the plurality of phases is detected in order that the detection state by the current detection means reaches a predetermined stable state. By setting based on the stabilization time (for example, a value according to the time characteristic of the output response of the current detection means), the current duration for each phase current in the DC side current actually detected by the current detection means, Even more appropriate values can be set.

  According to a fourth aspect of the present invention, there is provided a control device for an electric motor according to the present invention, wherein an inverter (for example, an implementation) for sequentially commutating energization to a plurality of phase motors by a pulse width modulation signal (for example, a PWM signal in the embodiment) And a current detection means (for example, a DC side current sensor 14b in the embodiment) for detecting a DC side current of the inverter (for example, a DC link current IDC in the embodiment). , Phase current estimating means for estimating the phase current of the electric motor (for example, each phase current Iu, Iv, Iw in the embodiment) based on the DC side current detected by the current detecting means (for example, implementation A phase current estimation unit 25) in the form and a switching control for controlling the on / off state of the switching element of the inverter based on the phase current estimated by the phase current estimation means. And a control unit (for example, the control unit 15 in the embodiment) that executes the above-mentioned control apparatus for an electric motor, wherein the pulse width modulation signal generating unit (for example, the pulse width modulation signal is generated by a carrier signal of a plurality of phases) The PWM signal generation unit 24) in the embodiment, and phase difference setting means for setting the phase difference of the carrier signal between the plurality of phases based on the torque and the rotational speed of the motor (for example, the level in the embodiment) And a phase difference calculator 33).

  According to the motor control device having the above-described configuration, each phase current in the DC-side current actually detected by the current detection means is set by setting the phase difference of the carrier signal between the plurality of phases based on the torque and the rotational speed of the motor. Each current duration can be set to an appropriate value. For example, the current duration becomes excessively short, which makes it difficult to detect the phase current, or the current duration becomes excessively long. Thus, it is possible to prevent the problem that the current ripple of the phase current increases.

  Furthermore, in the motor control device of the present invention according to claim 5, the phase difference setting means sets the phase difference to zero when the rotation speed of the motor is equal to or greater than a predetermined rotation speed. Yes.

  According to the motor control apparatus having the above configuration, when the rotation speed of the motor is equal to or higher than the predetermined rotation speed, the phase difference of the carrier signals between the phases is zero (that is, the pulse width modulation signal is generated by a single carrier signal). Can be detected from the DC side current with the desired accuracy. For example, a pulse width modulation signal is generated from a plurality of phase carrier signals having a phase difference other than zero. As compared with the case, it is possible to prevent the current ripple of the phase current estimated from the DC side current from increasing.

  According to the control apparatus for an electric motor of the present invention described in claim 1, for example, the current duration for each phase current detected according to various command values in switching control (that is, direct current in a single carrier cycle). Each phase current in the DC side current that is actually detected by the current detection means by setting the phase difference of the carrier signal between multiple phases based on the minimum value of the on-duty for each phase in the side current) Each current duration can be set to an appropriate value. For example, the current duration becomes excessively short, which makes it difficult to detect the phase current, or the current duration becomes excessively long. Thus, it is possible to prevent the problem that the current ripple of the phase current increases. As a result, even when the output voltage amplitude of each phase is relatively small, such as in a low rotation state where the rotational speed of the motor is relatively low, the phase current is estimated from the direct current. Reliability and estimation accuracy can be improved, and the electric motor can be appropriately controlled.

  Furthermore, according to the motor control device of the present invention as set forth in claim 2, a state in which the output voltage amplitude of each phase is relatively small, such as a low rotation state where the rotation speed of the motor is relatively low. Even so, the reliability and accuracy of estimation of the phase current from the direct current can be improved, and the electric motor can be controlled appropriately. On the other hand, when the minimum value of the current duration for each of the plurality of phases is less than the predetermined value, for example, by generating a pulse width modulation signal using a single carrier signal, for example, for a plurality of phases having a phase difference other than zero. As compared with the case where the pulse width modulation signal is generated by the carrier signal, it is possible to prevent the current ripple of the phase current estimated from the DC side current from increasing.

Furthermore, according to the control apparatus for an electric motor of the present invention described in claim 3, the current duration for each phase current in the DC side current actually detected by the current detection means is set to a more appropriate value. can do.
According to the control device for an electric motor of the present invention as set forth in claim 4, the phase difference of the carrier signal between a plurality of phases is set based on the torque and the rotational speed of the electric motor, so that it is actually detected by the current detecting means. The current duration of each phase current in the DC side current can be set to an appropriate value.For example, the current duration becomes excessively short, making it difficult to detect the phase current. It can be prevented that the problem that the current ripple of the phase current increases due to the excessively long duration is generated.

  Furthermore, according to the control device for an electric motor of the present invention described in claim 5, when the rotational speed of the motor is equal to or higher than a predetermined rotational speed, a pulse width modulation signal is generated by a single carrier signal. For example, it is possible to prevent an increase in the current ripple of the phase current estimated from the DC side current, as compared with the case where the pulse width modulation signal is generated by a plurality of phase carrier signals whose phase difference is not zero. .

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of an electric motor control device of the present invention will be described with reference to the accompanying drawings.
An electric motor control device 10 (hereinafter simply referred to as a motor control device 10) according to this embodiment is, for example, a brushless DC motor 12 (hereinafter simply referred to as a motor 12) mounted as a drive source together with an internal combustion engine 11 in a hybrid vehicle. The motor 12 is directly connected in series with the internal combustion engine 11 and has a rotor (not shown) having a permanent magnet used for the field and a rotating magnetic field for rotating the rotor. And a stator (not shown) to be generated.
For example, as shown in FIG. 1, the motor control device 10 includes a power drive unit (PDU) 14 that uses a battery 13 as a DC power source and a control unit 15.

In this motor control device 10, the drive and regenerative operation of a motor 12 having a plurality of phases (for example, U-phase, V-phase, and W-phase) is received by a control command output from the control unit 15 and is a power drive unit (PDU). 14.
For example, as shown in FIG. 2, the PDU 14 includes a pulse width modulation (including a bridge circuit 14 a formed by bridge connection using a plurality of transistor switching elements (for example, IGBT: Insulated Gate Bipolar Mode Transistor)) and a smoothing capacitor C ( A PWM inverter 14 </ b> A based on PWM) is connected to a high-voltage battery 13 that exchanges electric energy with the motor 12.

The PWM inverter 14A provided in the PDU 14 includes a high-side, low-side U-phase transistor UH, UL and a high-side, low-side V-phase transistors VH, VL and a high-side, low-side W-phase transistor WH that are paired for each phase. , WL and a smoothing capacitor C, and the transistors UH, VH, WH are connected to the positive terminal of the battery 13 to form a high side arm. UL, VL, and WL are connected to the negative terminal of the battery 13 to form a low-side arm, and the transistors UH, UL and VH, VL, WH, and WL that are paired for each phase are in series with the battery 13. Between the collector and emitter of each transistor UH, UL, VH, VL, WH, WL from the emitter. As a forward direction toward the collector, each diode DUH, DUL, DVH, DVL, DWH, DWL is connected.
Between the bridge circuit 14a and the negative terminal of the battery 13, a direct current sensor 14b that detects a direct current (DC link current) IDC of the PWM inverter 14A is provided.

  The PDU 14 sets a pair for each phase in the PWM inverter 14A based on a gate signal (that is, a PWM (pulse width modulation) signal) that is a switching command input from the control unit 15 when the motor 12 is driven, for example. The DC power supplied from the battery 13 is converted into three-phase AC power by switching the ON / OFF (cut-off) state of each of the transistors UH, UL and VH, VL and WH, WL. By sequentially commutating energization to the stator windings of the motor 12, AC U-phase current Iu, V-phase current Iv, and W-phase current Iw are passed through the stator windings of each phase.

The gate signal input from the control unit 15 to the PDU 14 is, for example, according to the combination of the on / off states of the transistors UH, UL and VH, VL, and WH, WL paired for each phase, for example, Table 1 and FIG. As shown in 3 (a) to (h), a PWM (pulse width modulation) signal corresponding to each of the eight switching states S1 to S8 is obtained.
Then, phase currents Iu, Iv, Iw are intermittently generated on the DC side of the PWM inverter 14A in accordance with the switching states S1 to S8, and the DC side current (DC link current) detected by the DC side current sensor 14b. ) IDC is one of the phase currents Iu, Iv, Iw, or one of the phase currents Iu, Iv, Iw inverted, or zero.

For example, one period (carrier period fc) of a carrier signal composed of a single triangular wave (or a plurality of triangular waves whose phase difference is zero) for each phase output voltage * Vu, * Vv, * Vw shown in FIG. In each of the times t1 to t8, the bridge circuit 14a is divided into a period from time t1 to time t2 that is the start timing of the carrier cycle fc and a period from time t7 to time t8 that is the end timing of the carrier cycle fc. The first switching state S1 in which the high side arm is turned on and the low side arm is turned off becomes the DC link current IDC becomes zero.
In the period from time t2 to time t3 and in the period from time t6 to time t7, which is the second switching state S2 in which the high-side U-phase and V-phase transistors UH and VH and the low-side W-phase transistor WL are turned on, The DC link current IDC is a current (−Iw) obtained by inverting the sign of the W-phase current Iw.
In the period from time t3 to time t4 and in the period from time t5 to time t6, which is the seventh switching state S7 in which the high-side U-phase transistor UH and the low-side V-phase and W-phase transistors UL and WL are turned on. The DC link current IDC becomes the U-phase current Iu.
The DC link current IDC is zero during the period from time t4 to time t5, which is the eighth switching state S8 in which the high side arm is off and the low side arm is on.

  The control unit 15 performs current feedback control on the dq coordinates forming the rotation orthogonal coordinates. For example, from the torque command Tr set according to the accelerator opening degree related to the accelerator operation by the driver, the Id command * Id. And Iq command * Iq are calculated, and each phase output voltage * Vu, * Vv, * Vw is calculated based on Id command * Id and Iq command * Iq, and each phase output voltage * Vu, * Vv, * Vw is calculated. In response, a PWM signal as a gate signal is input to the PDU 14, and each phase estimated current Ius, Ivs, Iws that is an estimated value for each phase current Iu, Iv, Iw that is actually supplied from the PDU 14 to the motor 12 is DC. A d-axis current Ids and a q-axis current Iqs obtained by estimating from the link current IDC and converting each phase estimated current Ius, Ivs, Iws on the dq coordinates, and an Id command * Id and Id Each deviation between the command * Iq is controlled to be zero.

The control unit 15 includes, for example, a current command calculation unit 21, a current control unit 22, a dq-3 phase conversion unit 23, a PWM signal generation unit 24, a phase current estimation unit 25, and a three phase-dq conversion unit. 26 and a rotation speed calculation unit 27.
The control unit 15 detects a DC side current (DC link current) IDC detected by the DC side current sensor 14b and a voltage sensor 13a that detects a terminal voltage (power supply voltage) VB of the battery 13. Value, a rotation angle of the rotor of the motor 12 (that is, a rotation angle of the magnetic pole of the rotor from a predetermined reference rotation position) θ, a detection signal output from the rotation sensor 12a, and an external control device (not shown) ) Is output.

  The current command calculation unit 21 is required according to, for example, a torque command Tr (for example, a depression amount of an accelerator pedal by a driver, a rotational speed ω of the motor 12, etc.) input from an external control device (not shown). Command values for causing the motor 12 to generate torque) and the rotational speed ω of the motor 12 input from the rotational speed calculator 27, the phase currents Iu, Iv, Iw supplied from the PDU 14 to the motor 12 are A current command for designating is calculated, and this current command is output to the current control unit 22 as an Id command * Id and a * Iq command * Iq on rotating rectangular coordinates.

  The dq coordinates forming the rotation orthogonal coordinates are, for example, a field magnetic flux direction by a permanent magnet of a rotor as a d axis (field axis), and a direction orthogonal to the d axis as a q axis (torque axis). It rotates in synchronization with the rotational phase of the 12 rotors. As a result, the Id command * Id and the Iq command * Iq, which are DC signals, are given as current commands for the AC signal supplied from the PDU 14 to each phase of the motor 12.

The current control unit 22 calculates a deviation ΔId between the Id command * Id and the d-axis current Ids and a deviation ΔIq between the Iq command * Iq and the q-axis current Iqs. For example, a motor input from the rotation speed calculation unit 27 By a PI (proportional integration) operation corresponding to the rotational speed ω, the deviation ΔId is controlled and amplified to calculate the d-axis voltage command value * Vd, and the deviation ΔIq is controlled and amplified to calculate the q-axis voltage command value * Vq.
The dq-3 phase conversion unit 23 uses the rotation angle θ of the rotor input from the rotation sensor 12a, and the d-axis voltage command value Vd and the q-axis voltage command value Vq on the dq coordinate are stationary coordinates. It is converted into a U-phase output voltage * Vu, a V-phase output voltage * Vv, and a W-phase output voltage * Vw, which are voltage command values on the three-phase AC coordinates.

  The PWM signal generation unit 24 is a carrier signal composed of, for example, sinusoidal output voltages * Vu, * Vv, * Vw, a triangular wave for each of a plurality of phases (for example, a three-phase triangular wave), or a single triangular wave. By the pulse width modulation based on the above, a gate signal (that is, PWM (pulse width), which is a switching command composed of pulses for driving on / off the transistors UH, UL and VH, VL, and WH, WL of the PWM inverter 14A of the PDU 14. Modulation) signal).

For example, as shown in FIG. 5, the PWM signal generation unit 24 includes a DUTY calculation unit 31, a current duration calculation unit 32, a phase difference calculation unit 33, a carrier signal switching unit 34, and a gate signal calculation unit 35. It is configured with.
The DUTY calculation unit 31 is a PWM inverter 14A obtained when pulse width modulation is performed using a carrier signal composed of a single triangular wave, based on the phase output voltages * Vu, * Vv, * Vw and the power supply voltage VB. The duty of each gate signal for turning on / off the transistors UH, UL and VH, VL and WH, WL, that is, the ratio of the on / off state is calculated.

  Based on the duty of each gate signal calculated by the DUTY calculator 31 and a predetermined carrier frequency stored in advance, the current duration calculator 32 calculates each phase in the DC link current IDC in a single carrier cycle fc. A current duration that is a duration of the currents Iu, Iv, and Iw, that is, a duration that is on-duty for each phase is calculated.

For example, in the DC link current IDC of the carrier cycle fc for each phase output voltage * Vu, * Vv, * Vw (* Vu> * Vv> * Vw) shown in FIG. 6A, the time t2 that is the fifth switching state S5 A period from time t3 to time t3 and a period from time t6 to time t7 are current durations of the W-phase current Iw. The period is the current duration of the U-phase current Iu, and the current duration of the V-phase current Iv is undetermined.
Further, for example, in the DC link current IDC of the carrier cycle fc for each phase output voltage * Vu, * Vv, * Vw (* Vu = * Vv> * Vw) shown in FIG. 6B, the fifth switching state S5. A period from time t2 to time t3 and a period from time t4 to time t5 are current durations of the W-phase current Iw, corresponding to either the fourth switching state S4 or the third switching state S3, U The current duration of either the phase current Iu or the V-phase current Iv is zero, and the current duration of the other of the U-phase current Iu or the V-phase current Iv is undetermined.

The phase difference calculation unit 33 is based on the current duration for each phase current Iu, Iv, Iw calculated by the current duration calculation unit 32, and the phase difference between the three-phase carrier signals composed of triangular waves for each of the plurality of phases. Is calculated.
For example, the phase difference calculation unit 33 selects the minimum current duration (minimum current duration) among the current durations for each phase current Iu, Iv, Iw calculated by the current duration calculation unit 32, When the minimum current duration is less than the predetermined time, a value obtained by subtracting the minimum current duration from the predetermined time is set as the phase difference. On the other hand, if the minimum current duration is greater than or equal to a predetermined value, the phase difference is set to zero.
The predetermined time, which is a determination threshold for the minimum current duration, is a value corresponding to, for example, the time characteristics of the output response of the DC-side current sensor 14b and the sampling time of the detection operation of the DC-side current sensor 14b. The detection stable time required for the actual detection state by the DC-side current sensor 14b to reach a predetermined stable state is at least longer than the detection stabilization time.

That is, for example, as shown in FIGS. 7A and 7B, the amplitude (or effective value) of each phase output voltage * Vu, * Vv, * Vw becomes a relatively small value, and each phase output voltage * Vu , * Vv, * Vw are in a state where the voltage difference between predetermined values (for example, zero, etc.) is less than or equal to a predetermined value (for example, zero), the current duration for each phase current Iu, Iv, Iw obtained by a single carrier signal is a predetermined time As a result, it may be difficult to detect the phase currents Iu, Iv, and Iw with the desired accuracy by the DC-side current sensor 14b.
For this reason, the current duration for each phase current Iu, Iv, Iw obtained when the pulse width modulation is executed by the three-phase carrier signal is set to be longer than at least the detection stabilization time of the DC-side current sensor 14b. Thus, the phase difference between the three-phase carrier signals is set.
Furthermore, when performing pulse width modulation with a three-phase carrier signal, the phase difference of the three-phase carrier signal increases (for example, from the phase difference p2 in FIG. 7B to the level in FIG. 7A). As the phase difference p1> p2 increases), the current ripple of each phase current Iu, Iv, Iw changes in an increasing trend, so that the current on the DC side current varies with the current duration for each phase current Iu, Iv, Iw. A value obtained by subtracting the minimum current duration from a predetermined time related to the detection stabilization time is set as the phase difference between the three-phase carrier signals for which the detection stabilization time of the sensor 14b is ensured.

On the other hand, for example, as shown in FIG. 7C, the amplitude (or effective value) of each phase output voltage * Vu, * Vv, * Vw becomes a relatively large value, and each phase output voltage * Vu, * Vv, * In a state where the voltage difference between Vw is larger than a predetermined value (for example, zero), the current duration for each phase current Iu, Iv, Iw obtained by a single carrier signal is After the predetermined time related to the detection stabilization time, the DC-side current sensor 14b can detect each phase current Iu, Iv, Iw with desired accuracy.
For this reason, the phase difference between the three-phase carrier signals is set to zero, that is, a state equivalent to the case where pulse width modulation is performed by a single carrier signal is set.

Based on the phase difference of the three-phase carrier signal calculated by the phase difference calculation unit 33, the carrier signal switching unit 34, when this phase difference is larger than zero, the three-phase consisting of a triangular wave having this phase difference. The carrier signal is output to the gate signal calculation unit 35, and when the phase difference is zero, the carrier signal composed of a single triangular wave is output to the gate signal calculation unit 35.
The gate signal calculation unit 34 performs pulse width modulation based on the three-phase or single carrier signal input from the carrier signal switching unit 34, each phase output voltage * Vu, * Vv, * Vw, and the power supply voltage VB. Then, a gate signal composed of pulses for driving on / off the transistors UH, UL and VH, VL and WH, WL of the PWM inverter 14A of the PDU 14 is generated.

The phase current estimation unit 25 is supplied to the stator windings of each phase of the motor 12 based on the DC link current IDC detected by the DC side current sensor 14b and the gate signal input from the PWM signal generation unit 24. Each phase estimation current Ius, Ivs, Iws, which is an estimated value for each phase current Iu, Iv, Iw, is estimated.
That is, the DC link current IDC detected by the DC-side current sensor 14b is obtained by inverting the sign of any one of the phase currents Iu, Iv, Iw, or any one of the phase currents Iu, Iv, Iw. Or, for example, based on Table 1 above, the DC link current IDC detected by the DC-side current sensor 14b in each of the switching states S2 to S7 of the PWM inverter 14A is converted into the estimated currents Ius, Ivs, Iws for each phase. Set as.

  For example, for each of the times t1 to t8 shown in FIG. 4, the DC link current detected by the DC-side current sensor 14b in the period from the time t2 to the time t3 and the period from the time t6 to the time t7 that are in the second switching state S2. IDC is set as a negative W-phase estimated current Iws (that is, -Iws). Further, the DC link current IDC detected by the DC-side current sensor 14b in the period from time t3 to time t4 and in the period from time t5 to time t6, which is the seventh switching state S7, is set as the positive U-phase estimated current Ius. To do.

  The three-phase-dq conversion unit 26 uses the rotation angle θ of the rotor input from the rotation sensor 12a to estimate each phase estimated current Ius, Ivs, which is a current on a stationary coordinate estimated by the phase current estimation unit 25. Iws is converted into a d-axis current Ids and a q-axis current Iqs on a rotation coordinate based on the rotation phase of the motor 12, that is, a dq coordinate.

  The rotation speed calculator 27 calculates the rotation speed ω of the motor 12 based on the detection signal output from the rotation sensor 12a, that is, the rotation angle of the rotor of the motor 12.

  The motor control device 10 according to the present embodiment has the above-described configuration. Next, the operation of the motor control device 10, in particular, the phase difference of three-phase carrier signals used when generating a gate signal by pulse width modulation is calculated. The setting process will be described with reference to the accompanying drawings.

First, in step S01 shown in FIG. 8, for example, based on the output voltages * Vu, * Vv, * Vw of each phase, the power supply voltage VB, and a predetermined carrier frequency, a pulse by a carrier signal consisting of a single triangular wave is assumed. A current duration which is a duration of each phase current Iu, Iv, Iw in the DC link current IDC in a single carrier period fc obtained when the width modulation is executed is calculated.
In step S02, the minimum current duration is acquired from the current duration for each phase current Iu, Iv, Iw. In this step S02, for example, as shown in FIG. 6B, any two phases of the phase output voltages * Vu, * Vv, * Vw or all phases are substantially equal within a predetermined value. If so, set the minimum current duration to zero.

In step S03, it is determined whether the minimum current duration is equal to or longer than a predetermined time.
If this determination is “NO”, the flow proceeds to step S 04, where the value obtained by subtracting the minimum current duration from the predetermined time is set as the phase difference, and the series of processes is terminated. .
On the other hand, if the determination result is “YES”, zero is set as the phase difference, and the series of processes is terminated.

  As described above, according to the motor control apparatus 10 according to the present embodiment, by setting the phase difference of the carrier signal between a plurality of phases based on the minimum value of the current duration for each phase current Iu, Iv, Iw. The current duration for each phase current Iu, Iv, Iw in the DC link current IDC actually detected by the DC side current sensor 14b can be set to an appropriate value, for example, the current duration becomes excessively short. As a result, it becomes difficult to detect the phase currents Iu, Iv, Iw, or the current ripple of the phase currents Iu, Iv, Iw increases due to, for example, an excessively long current duration. Problems can be prevented from occurring. Thus, even when the amplitude of each phase output voltage * Vu, * Vv, * Vw is relatively small, such as in a low-rotation state where the rotational speed ω of the motor 12 is relatively low, the DC Reliability and estimation accuracy in estimating each phase current Iu, Iv, Iw from link current IDC can be improved, and motor 12 can be controlled appropriately.

  In the above-described embodiment, as shown in step S01, each phase current Iu, Iv is based on each phase output voltage * Vu, * Vv, * Vw, power supply voltage VB, and a predetermined carrier frequency. , Iw current duration and three-phase carrier signal phase difference are calculated, but the present invention is not limited to this. For example, as shown in FIG. , Predetermined regions (for example, FIG. 5) corresponding to a three-phase carrier signal for each of a plurality of phase differences (for example, phase differences pa, pb, pc (pa> pb> pc), etc.) and a single carrier signal. 9 is set in accordance with the rotational speed ω of the motor 12 calculated by the rotational speed calculation unit 27 and the torque command Tr. Three-phase carrier with phase difference You may select a signal or a single-carrier signal.

  On the two-dimensional map based on the rotation speed and torque, the amplitude (or effective value) of each phase output voltage * Vu, * Vv, * Vw becomes a relatively small value, and each phase output voltage * Vu, * Corresponding to the state in which the voltage difference between Vv and * Vw is equal to or less than a predetermined value (for example, zero), for example, the phase difference of the three-phase carrier signal tends to increase as the rotational speed decreases. It is set to change.

In the above-described embodiment, as shown in step S03, it is determined whether or not the minimum current duration is equal to or longer than a predetermined time. However, the present invention is not limited to this. For example, as shown in FIG. Instead of the processes in steps S03 to S05, the processes in steps S11 to S13 may be executed.
That is, in this modification, in step S11, a value obtained by subtracting the minimum current duration from the predetermined time is set as the phase difference.
In step S12, it is determined whether or not the phase difference is equal to or less than zero.
When the determination result is “NO”, the series of processes is terminated.
On the other hand, if this determination is “YES”, the flow proceeds to step S 13, where the phase difference is set to zero, and the series of processes is terminated.

It is a block diagram of the control apparatus of the electric motor which concerns on embodiment of this invention. It is a block diagram of the PWM inverter of PDU shown in FIG. It is a figure which shows each switching state S1-S8 of the PWM inverter shown in FIG. Changes in the PWM signal and each phase current Iu, Iv, Iw and DC link current IDC in one cycle (carrier cycle fc) of a carrier signal composed of a single triangular wave with respect to each phase output voltage * Vu, * Vv, * Vw It is a graph which shows an example. It is a block diagram of the PWM signal generation part shown in FIG. 6A and 6B show changes in the PWM signal and the DC link current IDC in one cycle (carrier cycle fc) of a carrier signal composed of a single triangular wave for each phase output voltage * Vu, * Vv, * Vw. It is a graph which shows the example of. FIGS. 7A and 7B show changes in the PWM signal and the DC link current IDC in one cycle (carrier cycle fc) of a carrier signal composed of a three-phase triangular wave for each phase output voltage * Vu, * Vv, * Vw. FIG. 7C is a graph showing an example of the PWM signal and DC in one cycle (carrier cycle fc) of a single triangular wave for each phase output voltage * Vu, * Vv, * Vw. It is a graph which shows the example of a change of link current IDC. It is a flowchart which shows the process which sets the phase difference of the carrier signal of 3 phases which concerns on embodiment of this invention. It is a graph which shows an example of the predetermined | prescribed each area | region corresponding to the three-phase carrier signal for every several phase difference set on the two-dimensional map by the rotation speed and torque of a motor, and a single carrier signal. It is a flowchart which shows the process which sets the phase difference of the carrier signal of 3 phases which concerns on the modification of embodiment of this invention.

Explanation of symbols

10 Motor Control Device 12 Motor 14 PWM Inverter (Inverter)
14b DC side current sensor (current detection means)
15 Control unit (control means)
24 PWM signal generator (pulse width modulation signal generator)
25 Phase current estimation unit (phase current estimation means)
32 Current duration calculation unit (current duration detection means)
33 Phase difference calculation unit (phase difference setting means)
Step S03: determination means, predetermined value setting means

Claims (5)

An inverter that sequentially commutates energization of the motors of the plurality of phases by the pulse width modulation signal, current detection means that detects a DC side current of the inverter, and the DC side current detected by the current detection means based on the DC side current Phase current estimation means for estimating the phase current of the electric motor, and control means for executing switching control for controlling the on / off state of the switching element of the inverter based on the phase current estimated by the phase current estimation means. A control device for an electric motor,
Pulse width modulation signal generating means for generating the pulse width modulation signal by a carrier signal of a plurality of phases;
A current duration detecting means for detecting a current duration which is a duration of a phase current for each of the plurality of phases in the DC side current in a single carrier cycle;
Phase difference setting means for setting a phase difference of the carrier signal between the plurality of phases based on a minimum value of the current duration for each of the plurality of phases detected by the current duration detection means. An electric motor control device. A determination means for determining whether or not a minimum value of the current duration for each of the plurality of phases detected by the current duration detection means is a predetermined value or more;
The phase difference setting means, when the determination means determines that the minimum value is less than the predetermined value, a value obtained by subtracting the minimum value from the predetermined value as the phase difference, The motor control device according to claim 1, wherein the phase difference is set to zero when the determination unit determines that the minimum value is equal to or greater than the predetermined value. 3. The motor control according to claim 2, further comprising predetermined value setting means for setting the predetermined value based on a detection stabilization time required for the detection state by the current detection means to reach a predetermined stable state. apparatus. An inverter that sequentially commutates energization of the motors of the plurality of phases by the pulse width modulation signal, current detection means that detects a DC side current of the inverter, and the DC side current detected by the current detection means based on the DC side current Phase current estimation means for estimating the phase current of the electric motor, and control means for executing switching control for controlling the on / off state of the switching element of the inverter based on the phase current estimated by the phase current estimation means. A control device for an electric motor,
Pulse width modulation signal generating means for generating the pulse width modulation signal by a carrier signal of a plurality of phases;
A motor control apparatus comprising: phase difference setting means for setting a phase difference of the carrier signal between the plurality of phases based on the torque and rotation speed of the motor. The motor control device according to claim 4, wherein the phase difference setting unit sets the phase difference to zero when the rotation speed of the motor is equal to or greater than a predetermined rotation speed.

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