JP7323447B2 - Permanent magnet synchronous machine controller and method - Google Patents

Description

Article 30, Paragraph 2 of the Patent Act applies. Published at the 2019 Institute of Electrical Engineers of Japan Industry Application Society Conference on August 20-22, 2019.

The present invention relates to a permanent magnet synchronous machine control device and method thereof.

Most of the industrial equipment is driven by motors (electric motors), and electric motors account for as much as 50% of domestic power consumption. In order to reduce this power consumption, the development of permanent magnet synchronous motors, which are highly efficient and can be further reduced in size and weight, has been promoted. Unlike induction motors, permanent magnet synchronous motors have no slippage, and it is necessary to control the inverter according to the rotation angle of the rotor.

The control of the inverter performs VVVF (Variable Voltage Variable Frequency) control for controlling the output voltage and output frequency applied to the motor depending on the rotor speed and rotor position of the motor.

In addition, an inverter is a converter that converts DC power into AC power. (to be described later) outputs an AC voltage.

Such a control method is called PWM (Pulse Width Modulation) control and is widely used for inverter control. There are various types of PWM control methods. Depending on the output voltage and frequency, PWM control can be applied depending on the operating point of the motor. The modulation scheme (hereinafter referred to as modulation scheme) may be switched. That is, the operation may be performed while switching the modulation method according to the output voltage of the inverter.

On the other hand, as described above, since the permanent magnet synchronous motor needs to control the inverter according to the rotation angle of the rotor, a position sensor such as an encoder or resolver is usually required. However, in recent years, for the purpose of miniaturization, maintenance saving, reliability improvement, and cost reduction, a position sensorless control system that performs control without such a position sensor such as an encoder or resolver is used.

Conventionally, it is known that the extended induced voltage method can be applied to position sensorless control by detecting an estimated axis error. This extended induced voltage method estimates the axis error of the rotating shaft with respect to a specified rotating magnetic field based on whether the current value returned from the load deviates from the expected value with respect to the current supplied to the load. It is a method that can apply the principle that can be applied to position sensorless control.

With this extended induced voltage method, in the permanent magnet synchronous machine control device, if the rotation speed is in the medium to high speed range, the detection obtained by the phase current detection unit interposed between the power converter and the load A value can be used to indirectly detect the estimated axis error. Therefore, according to this extended induced voltage method, position sensorless control is possible.

However, this extended induced voltage method has some imperfections in the operating state from the time of startup to the middle and low speed range. In particular, when the motor is stopped, no induced voltage (back electromotive force) is generated for determining whether the rotor magnetic poles of the motor are NS or NS. Therefore, if the polarity is erroneously determined, there is a problem that the motor reverses.

On the other hand, as a position sensorless control of a permanent magnet synchronous machine, a method of superimposing a harmonic voltage on a drive current instead of an induced voltage that is difficult to obtain in the operating state from startup to medium and low speed regions is becoming popular. According to this, when a harmonic voltage is superimposed, the harmonic current value generated in the motor changes according to the inductance ratio (saliency). , the magnetic pole polarities of the N pole and S pole of the permanent magnet. Patent Document 1 discloses such a method.

In Patent Document 1, the relationship between the inductance and the current in the magnetic pole direction is such that the direction of current that strengthens the magnetic flux of the magnet is defined as the positive direction, and the direction of current that weakens the magnetic flux of the magnet is defined as the negative direction. , in a magnetic pole polarity discriminating device for discriminating the magnetic pole polarity of a permanent magnet synchronous motor having a characteristic that the inductance in the magnetic pole direction monotonously decreases when a current greater than the maximum point is passed in the positive direction, the magnetic pole polarity discriminating section includes the positive direction and the The side where the inductance in the magnetic pole direction increases when the same predetermined current value is applied in the negative direction is determined to be the N pole side.

Japanese Patent Application Laid-Open No. 2014-11822

In the above-described extended induced voltage method, the induced voltage cannot be obtained unless the permanent magnet synchronous motor rotates at a certain speed, so the magnetic pole polarity determination performance is inferior in the low speed region. It is necessary to compensate for this, and in the low speed region from start to constant speed, it is necessary to use a magnetic pole polarity determination method for a permanent magnet synchronous motor by superimposing harmonics, as disclosed in Patent Document 1. become more sexual.

In addition, when a permanent magnet synchronous machine control device is realized by a three-level inverter, the output voltage changes greatly when harmonics for polarity discrimination are superimposed, so the PWM control modulation method based on the changed output voltage switching may occur. When the modulation method is switched, the output voltage is different for each modulation method, making it difficult to stably determine the polarity.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and its object is to provide a permanent magnet synchronous machine controller capable of stably discriminating the polarity against the polarity discrimination that becomes unstable due to the switching of the modulation method. to provide.

The present invention for solving the above problems is a permanent magnet synchronous machine control device having a power converter that supplies drive power to the permanent magnet synchronous machine, and a controller that controls the power converter, wherein the controller comprises: Based on the current detected by the voltage command generator that can superimpose harmonics and generate an output voltage, the current detector that detects the current flowing between the power converter and the permanent magnet synchronous machine, and the current detected by the current detector and a magnetic pole polarity discriminating unit that discriminates the magnetic pole polarity of the permanent magnet synchronous machine, and the controller switches the modulation method of harmonic superimposition to a method according to the output voltage. When the magnetic pole polarity is determined by superimposing harmonics on the output voltage, the switching of the modulation method is stopped.

ADVANTAGE OF THE INVENTION According to this invention, the permanent-magnet synchronous machine control apparatus which can stabilize polarity discrimination|determination can be provided with respect to the polarity discrimination|determination which becomes unstable by switching of a modulation system.

1 is a block diagram showing a configuration example of a permanent magnet synchronous machine control device according to a first embodiment; FIG. 4 is a diagram showing definitions of coordinate systems and symbols used in controlling the permanent magnet synchronous machine of the first embodiment; FIG. FIG. 2 is a block diagram showing a configuration example of a position/velocity estimation calculation unit in FIG. 1; FIG. 4 is a block diagram showing a configuration example of a magnetic pole polarity determination unit in FIG. 3; FIG. 2 is a block diagram showing a configuration example of a superimposed voltage calculator in FIG. 1; FIG. 6 is a block diagram showing a configuration example of an AC voltage component applying section in FIG. 5; 4 is a graph illustrating the relationship between the harmonic superimposed voltage command and the d-axis current waveform in Example 1. FIG. FIG. 4 is a diagram showing an example of a modulation scheme according to the first embodiment; FIG. 4 is a diagram showing an example of a harmonic superimposed voltage in Example 1; 4 is a flowchart of modulation scheme determination when superimposing harmonics in the first embodiment; 8 is a graph comparing changes in d-axis current with FIG. 7 when the carrier frequency is changed in Example 1. FIG. FIG. 10 is a flowchart of modulation method determination when superimposing harmonics according to the second embodiment; FIG. 8 is a graph comparing changes in d-axis current with FIG. 7 when the amount of superimposition is changed in Example 2. FIG.

Hereinafter, a permanent magnet synchronous machine control device and its system according to an embodiment of the present invention will be described with reference to the drawings. Example 1 will be described using FIGS. 1 to 12, and Example 2 will be described using FIGS. 12 and 13. FIG. Example 2 differs from Example 1 in that the amount of superimposed harmonics is changed.

FIG. 1 is a block diagram showing a configuration example of a permanent magnet synchronous machine drive system according to a first embodiment. The permanent magnet synchronous machine drive system of FIG. A command generator 105 that generates a torque command value Tm* for the synchronous machine 103 and a phase current detector 121 that detects a current flowing through the permanent magnet synchronous machine 103 are provided.

Although the main function of the permanent magnet synchronous machine 103 is that of an electric motor during power running, it functions as a generator during regeneration, so it is called the permanent magnet synchronous machine 103 . The power converter 102 is, for example, a three-level inverter that is representative of a multi-level inverter that switches between on and off in multiple stages to easily obtain an output that approximates a sine wave.

A 3-level inverter has higher performance than a 2-level inverter and is also suitable for high power applications. The power converter 102 includes input terminals 123a and 123b for supplying power to the power converter 102, a main circuit section 132 composed of 12 switching elements S1 to S12, and a gate for directly driving the main circuit section 132. - A driver 133 and a smoothing capacitor 131 are provided.

Based on the gate command signal generated by the controller 101, the power converter 102 converts the DC power supplied from the input terminals 123a and 123b into three-phase AC power, and converts the three-phase AC power to the permanent magnet synchronous machine 103. supply to Phase current detector 121 detects AC currents iu and iw flowing from power converter 102 to permanent magnet synchronous machine 103 . The phase current detector 121 is realized by, for example, a current sensor using a Hall element.

The phase current detection unit 121 in FIG. 1 is configured to detect alternating current by two-phase detection of U phase and W phase. good too. The command generator 105 is a controller located above the controller 101 and generates a torque command value Tm* to be input to the permanent magnet synchronous machine 103 .

In the permanent magnet synchronous machine control device, the controller 101, the power converter 102, the permanent magnet synchronous machine 103, and the phase current detector 121 shown in FIG. , the torque command value Tm* to each permanent magnet synchronous machine 103 may be commanded at the same time. For example, it is suitable for uniformly controlling the operation of trains each having a dedicated motor for each axle.

Controller 101 controls torque generated by permanent magnet synchronous machine 103 based on torque command value Tm* from command generator 105 . As this upper controller, for example, a current controller is used to control the current flowing through the permanent magnet synchronous machine 103, or a speed controller or a position controller is used to control the rotation speed or position. Used.

Note that the controller 101 in FIG. 1 operates as a torque controller because it is intended to control torque. The controller 101 includes a vector control unit 111, a position/speed estimation calculation unit 112, a three-phase coordinate conversion unit 113, a dq coordinate conversion unit 114, a PWM signal controller 115, a current detection unit 116, a superimposed voltage A calculation unit 117 is provided.

The controller 101 controls the current control system based on the alternating current detection values Iu and Iw, which are the detection values of the alternating currents iu and iw flowing through the permanent magnet synchronous machine 103, and the torque command value Tm* from the command generator 105. and the calculation result of the phase control system, a gate command signal for driving (switching operation) the switching element of the power converter 102 is generated and supplied to the gate driver 133 of the power converter 102 .

FIG. 2 is a diagram showing definitions of coordinate systems and symbols used in controlling the permanent magnet synchronous machine 103 of FIG. Note that (-axis) in FIG. 2 is replaced with "axis" here. In FIG. 2, the ab-axis coordinate system defined by the a-axis and the b-axis is the stator coordinate system representing the phase of the stator winding of the permanent magnet synchronous machine 103, and the a-axis is generally the permanent magnet synchronous machine. A 103 u-phase winding phase is applied to the reference.

A dq-axis coordinate system defined by the d-axis and the q-axis is a rotor coordinate system representing the magnetic pole position of the rotor of the permanent magnet synchronous machine 103, and rotates in synchronization with the rotor magnetic pole position of the permanent magnet synchronous machine 103. do. In the case of a permanent magnet synchronous machine, the d-axis is generally applied to the north pole direction of the magnetic poles of the permanent magnets attached to the rotor, and the d-axis is also called the magnetic pole axis.

The dc-qc axis coordinate system defined by the dc axis and the qc axis is the estimated phase of the rotor magnetic pole position of the permanent magnet synchronous machine 103, that is, the coordinate system assumed by the controller 101 to be in the d-axis and q-axis directions. Yes, also called the control axis. A pz-axis coordinate system defined by the p-axis and the z-axis is a coordinate system representing the phase on which the high-frequency voltage command is superimposed. Coordinate axes combined in each coordinate system are orthogonal to each other.

In each coordinate system described above, as shown in FIG. 2, the phases of the d-axis, dc-axis, and p-axis relative to the a-axis are expressed as θd, θdc, and θp, respectively. Also, the deviation of the dc axis from the d axis is represented by Δθc, and the deviation of the p axis from the dc axis is represented by Δθpd.

In FIG. 1, the vector control unit 111 has current command values Idc* and Iqc* on the dc-qc axis coordinate system calculated based on the torque command value Tm* of the command generator 105, and the dq coordinate conversion unit 114 Current control is performed to match the output dc-axis current detection value Idc and qc-axis current detection value Iqc, and a dc-axis voltage command value Vdc* and a qc-axis voltage command value Vqc* are output as calculation results.

The position/speed estimation calculation unit 112 calculates the dc-axis voltage command value Vdc* and the qc-axis voltage command value Vqc* output by the vector control unit 111, and the dc-axis superimposed voltage command value Vdh* and Vdh* output by the superimposed voltage calculation unit 117. Based on the qc-axis superimposed voltage command value Vqh* and the dc-axis current detection value Idc and qc-axis current detection value Iqc output by the dq-coordinate conversion unit 114, the drive frequency estimated value ωr̂ and the control phase of the permanent magnet synchronous machine 103 are determined. θdc is calculated and output.

The three-phase coordinate conversion unit 113 applies the dc-axis superimposed voltage command values Vdh* and qc* output by the superimposed voltage calculation unit 117 to the dc-axis voltage command value Vdc* and the qc-axis current command value Vqc* output by the vector control unit 111. The dc-axis voltage command value Vdc** and the qc-axis voltage command value Vqc** obtained by adding the shaft superimposed voltage command value Vqh* are calculated based on the control phase θdc output by the position/speed estimation calculation unit 112, and the three-phase voltage command Vu *, Vv*, and Vw*, and output to the PWM signal controller 115 .

The dq coordinate conversion unit 114 converts the three-phase current detection values Iu, Iv, and Iw output by the current detection unit 116 into the dc-axis current detection values Idc and Iw based on the control phase θdc output by the position/speed estimation calculation unit 112. It converts to the qc-axis current detection value Iqc and outputs it.

The PWM signal controller 115 generates a triangular wave carrier based on an arbitrary carrier frequency fc and the voltage detection value Ecf of the smoothing capacitor 131, and generates a triangular wave carrier based on the triangular wave carrier and the three-phase AC voltage commands Vu*, Vv*, Vw*. Pulse width modulation is performed by comparing the magnitude with the modulated wave.

The switching element of power converter 102 is on/off controlled by the gate command signal generated by the calculation result of this pulse width modulation. The PWM signal controller 115 also outputs a current detection timing setting signal SAH that determines the current detection timing of the current detector 116 . The current detection timing setting signal SAH is, for example, a triangular wave carrier.

Current detection unit 116 calculates three-phase current detection values Iu, Iv, and Iw from alternating currents iu and iw detected by phase current detection unit 121, based on current detection timing setting signal SAH output from PWM signal controller 115. and output to the dq coordinate transformation unit 114 .

Based on the dc-axis current detection value Idc and the qc-axis current detection value Iqc output by the dq coordinate conversion unit 114 and the current detection timing setting signal SAH output by the PWM signal controller 115, the superimposed voltage calculation unit 117 generates a permanent magnet A dc-axis superimposed voltage command value Vdh* and a qc-axis superimposed voltage command value Vqh* for generating a high-frequency current (pulsating current) in the synchronous machine 103 are calculated and output.

FIG. 3 is a block diagram showing a configuration example of the position/velocity estimation calculation unit 112 in FIG. As shown in FIG. 3 , the position/speed estimation calculation unit 112 includes a magnetic pole polarity determination unit 201 , an axis error estimation calculation unit 202 , a speed estimation calculation unit 203 and a position estimation calculation unit 204 . The position/speed estimation calculation unit 112 performs phase control to match (synchronize) the d-axis, which is the rotor magnetic pole phase of the permanent magnet synchronous machine 103, with the dc-axis, which is the control phase.

The axis error estimation calculation unit 202 calculates the dc-axis voltage command value Vdc* and the qc-axis voltage command value Vqc* output by the vector control unit 111, and the dc-axis superimposed voltage command values Vdh* and qc* output by the superimposed voltage calculation unit 117. Based on the shaft superimposed voltage command value Vqh*, the dc-axis current detection value Idc and the qc-axis current detection value Iqc output by the dq coordinate conversion unit 114, and the drive frequency estimation value ωr^ output by the speed estimation calculation unit 203. Then, an axis error estimated value Δθĉ, which is the deviation between the d-axis and the dc-axis, is calculated and output to the speed estimation calculation section 203 .

The speed estimation calculation unit 203 calculates and outputs the drive frequency estimation value ωr̂ of the permanent magnet synchronous machine 103 based on the axis error estimation value Δθĉ output by the axis error estimation calculation unit 202 .

The position estimation calculation unit 204 calculates and outputs a reference control phase θdc0, which is the estimated phase of the rotor magnetic pole position of the permanent magnet synchronous machine 103, based on the drive frequency estimation value ωr^ output by the speed estimation calculation unit 203. Further, the position/speed estimation calculation unit 112 adds the magnetic pole polarity correction phase θpn output by the magnetic pole polarity determination unit 201 to the reference control phase θdc0 to output the control phase θdc.

FIG. 4 is a block diagram showing a configuration example of the magnetic pole polarity discriminator 201 of FIG. As shown in FIG. 4, the magnetic pole polarity determination unit 201 includes an inductance calculation unit 210 and a polarity determination/reversal processing unit 215. The inductance calculation unit 210 includes a first inductance calculation unit 211 and a second inductance calculation. 212 , a third inductance calculator 213 , and a fourth inductance calculator 214 .

In the magnetic pole polarity determination unit 201, the positive current values of the dc-axis current detection value Idc and the qc-axis current detection value Iqc of the pulsating current flowing in the permanent magnet synchronous machine 103 and the pulsating current are calculated by the first inductance calculation unit 211. Based on the dc-axis superimposed voltage command value Vdh* and the qc-axis superimposed voltage command value Vqh* to be generated, a first inductance value Ldc1+ is calculated with respect to a positive current change on the dc-qc axis coordinate system, and the polarity Output to the discrimination/inversion processing unit 215 .

Further, in the second inductance calculation unit 212, a positive current value different from the first inductance value Ld1+ of the dc-axis current detection value Idc and the qc-axis current detection value Iqc of the pulsating current flowing through the permanent magnet synchronous machine 103 and , based on the dc-axis superimposed voltage command value Vdh* and the qc-axis superimposed voltage command value Vqh* that generate the pulsating current, the second inductance value Ldc2+ with respect to the positive current change on the dc-qc axis coordinate system Calculate and output to the polarity discrimination/inversion processing unit 215 .

Furthermore, in the third inductance calculation unit 213, negative current values of the dc-axis current detection value Idc and the qc-axis current detection value Iqc of the pulsating current flowing in the permanent magnet synchronous machine 103 and the dc-axis superimposition that generates the pulsating current are calculated. Based on the voltage command value Vdh* and the qc-axis superimposed voltage command value Vqh*, the third inductance value Ldc1- is calculated with respect to the negative current change on the dc-qc axis coordinate system, and the polarity determination/reversal process is performed. Output to unit 215 .

Furthermore, in the fourth inductance calculation unit 214, a negative current value different from the third inductance value Ld1− of the dc-axis current detection value Idc and the qc-axis current detection value Iqc of the pulsating current flowing in the permanent magnet synchronous machine 103 Then, based on the dc-axis superimposed voltage command value Vdh* and the qc-axis superimposed voltage command value Vqh* that generate the pulsating current, the fourth inductance value Ldc2 with respect to the negative current change on the dc-qc axis coordinate system − is calculated and output to the polarity determination/inversion processing unit 215 .

Then, in the polarity determination/reversal processing unit 215, the deviation amount ΔLdc+ between the first inductance value Ldc1+ and the second inductance value Ldc2 with respect to the current change of the positive value on the dc-qc axis coordinate system and the dc-qc axis A deviation amount ΔLdc- between the third inductance value Ldc1- and the fourth inductance value Ldc2- with respect to the negative current change on the coordinate system is calculated.

Further, the absolute values of the deviation amount ΔLdc+ and the deviation amount ΔLdc− are calculated, and the side where the absolute value of the inductance deviation amount is large is determined as the N pole direction (d-axis direction) of the permanent magnet synchronous machine 103 . The polarity discrimination/reversal processing unit 215 discriminates the N-pole direction of the rotor magnetic poles of the permanent magnet synchronous machine 103 using the magnetic saturation characteristics of the rotor iron core.

As a result, when the rotor magnetic pole position estimated by the position estimation calculation section 204 is shifted by 180 degrees, the magnetic pole polarity correction phase θpn outputs 180 degrees in order to reverse the control phase θdc. As a result of the polarity discrimination, if the N pole direction of the magnetic poles of the rotor does not deviate from the control phase θdc, the magnetic pole polarity correction phase θpn outputs 0 degrees.

FIG. 5 is a block diagram showing a configuration example of the superimposed voltage calculator 117 in FIG. As shown in FIG. 5 , the superimposed voltage calculator 117 includes an AC voltage component application unit 701 , a superimposed voltage phase correction table 702 , and a dq coordinate conversion unit 703 .

Based on the current detection timing setting signal SAH output from PWM signal controller 115, AC voltage component applying section 701 applies p-axis superimposed AC voltage command Vp-ac*, z-axis superimposed AC voltage command Vz-ac*, is calculated and output to the dq coordinate transformation unit 703 .

The superimposed voltage phase correction table 702 superimposes a voltage command for generating a pulsating current in the permanent magnet synchronous machine 103 based on the dc-axis current detection value Idc and the qc-axis current detection value Iqc output by the dq coordinate conversion unit 114. A deviation amount Δθpd between the p-axis, which is the coordinate system to be controlled, and the dc-axis, which is the control coordinate system, is calculated and output to the dq coordinate conversion unit 703 .

The dq coordinate conversion unit 703 converts the p-axis superimposed AC voltage command Vp-ac* output by the AC voltage component application unit 701 and the z-axis superimposed AC voltage command Vz-ac* to the superimposed voltage phase correction table 702. Based on the p-axis and the deviation amount Δθpd of the dc-axis, the dc-axis superimposed voltage command value Vdh* and the dc-axis superimposed voltage command value Vqh* are converted and output.

FIG. 6 is a block diagram showing a configuration example of the AC voltage component applying section 701 of FIG. As shown in FIG. 6, the AC voltage component applying unit 701 includes AC waveform generators 711 and 713, switches 712 and 714 for switching the amplitude of the AC voltage waveform, and AC waveform generators. Multipliers 804 and 805 are provided for multiplying the output values of 711 and AC waveform generator 713 by the output values of switches 712 and 714 and outputting the results.

The AC voltage component applying unit 701 generates a p-axis AC voltage waveform Sp-ac for the AC waveform generators 711 and 713 to generate a pulsating current in the permanent magnet synchronous machine 103 based on the current detection timing setting signal SAH. * and z-axis AC voltage waveform Sz-ac*.

Switches 712 and 714 are switches for controlling the amplitudes of the p-axis AC voltage waveform Sp-ac* and the z-axis AC voltage waveform Sz-ac* superimposed on the pz-axis coordinate system. In multipliers 804 and 805, p-axis AC voltage waveform Sp-ac* and z-axis AC voltage waveform Sz-ac* output by AC waveform generator 711 and AC waveform generator 713, and switches 712 and 714. By multiplying the p-axis AC voltage component amplitude command Kp-ac_amp* and the z-axis AC voltage component amplitude command Kz-ac_amp* output by the p-axis superimposed AC voltage command Vp-ac* and the z-axis superimposed AC A voltage command Vz-ac* is output.

In the polarity discrimination means of the prior art, the output voltages Vu, Vv, and Vw (collectively referred to as _V1 ) change greatly when the harmonic voltage is superimposed. If the modulation method, which is determined by the modulation factor calculated based on the output voltage, is switched during harmonic superimposition, the output voltage differs depending on the modulation method, so there is a risk that the polarity of the magnetic pole will fail to be determined and the polarity will be reversed. . Modulation factor Vc is calculated by, for example, the following equations (1) to (3).

Note that Vmax in the above equation (1) is the maximum output voltage, Ecf is the filter capacitor voltage, _V1 in the above equation (2) is the output voltage, Ld is the d-axis inductance, and _id is the d-axis when the harmonic voltage is superimposed. dt is a current peak value, and dt is a time width calculated from the carrier frequency fc in PWM modulation. Next, specific means for applying an AC voltage command in the magnetic pole direction of the permanent magnet synchronous machine 103 to determine the polarity will be described with reference to FIGS. 7 to 9. FIG.

FIG. 7 is a graph illustrating the relationship between the harmonic superimposed voltage command and the d-axis current waveform. The horizontal axis of FIG. 7 is the time axis, and clearly indicates the time width dt calculated from the carrier frequency fc as shown in the above equation (2). Here, as shown in the upper part of FIG. 7, since the harmonic superposition period is set to 1/(fc/2), the PWM peak-valley period dt is illustrated as half of the PWM period of 1/fc. However, this time width dt may be set regardless of the PWM carrier frequency fc. Note that the time width dt and the carrier frequency fc have no direct relationship with the rotation speed of the permanent magnet synchronous machine 103 .

As described with reference to FIGS. 1 to 3, the superimposed voltage calculator 117 outputs the dc-axis superimposed voltage command value Vdh* and the qc-axis superimposed voltage command value Vqh*. Through the processing of the control unit 111 and the three-phase coordinate conversion unit 113 , the three-phase voltage commands Vu*, Vv*, and Vw* are converted and output to the PWM signal controller 115 .

These three-phase voltage commands Vu*, Vv*, and Vw* are collectively referred to as a superimposed voltage command V1* shown in FIG. 7(a). Also shown are the U-phase voltage command Vu* in FIG. 7(b) and the V- and W-phase voltage commands Vv* in FIG. 7(c). Corresponding to these, the positive/negative sides Vup* and Vun of the U-phase voltage command in FIG. 7(d) and the positive/negative sides Vvp* and Vvn of the V- and W-phase voltage commands in FIG. , Vwp*, Vwn.

The PWM signal controller 115 that receives these inputs drives the switching elements S1 to S12 of the power converter 102 based on the calculation results of the current control system and the phase control system based on the torque command value Tm* from the command generator 105. A gate command signal for the power converter 102 is generated and supplied to the gate driver 133 of the power converter 102 .

As a result, the power converter 102 outputs the three-phase voltages Vu, Vv, and Vw based on the input terminal 123b, that is, the three-phase line voltages Vuv, Vvw, and Vwu to the permanent magnet synchronous machine 103 to drive it. . Of these, FIG. 7(f) shows the line voltage Vuv. Correspondingly, FIG. 7(g) shows the d-axis current detection value id, and FIG. 7(h) shows the p-axis current detection value .DELTA.id. dt shown in FIG. 7 is 1/2 period of the carrier frequency fc.

In FIG. 7, when the voltage superposition command values shown in (a) to (e) are superimposed, the line voltage Vuv shown in (f) is actually applied to the permanent magnet synchronous machine 103 . Then, the d-axis current i _d is influenced by magnetic saturation, and becomes an asymmetric pulsating waveform with respect to positive and negative as shown in FIG. 7(g). The asymmetry of this waveform is used to determine the polarity of the magnetic pole. In this example, since di _d1 <d _d2 , the negative direction is the north pole direction (d-axis direction) of the electric motor.

FIG. 8 is a diagram showing an example of a modulation scheme, where A is amplitude and B is bias. In FIG. 8, the fundamental modulated wave a shown in (a) is divided into two by A/2, and the bias B is superimposed to obtain a positive bias modulated wave abp and a negative bias modulated wave shown in (b) and (c). abn and . FIG. 8(d) is the positive side modulated wave ap, FIG. 8(e) is the positive/negative side modulated wave an, and FIG. 8(h) is the output voltage.

(b) of FIG. 8(h) is a dipolar modulation method. This is a 3-level PWM control system devised by B. Velaerts et al., and outputs positive and negative output voltage pulses alternately through zero voltage. >0 region. On the other hand, (b) in FIG. 8(h) is a unipolar modulation method. This is the region of bias B=0, consisting of pulse trains of the same polarity during half cycles.

FIG. 9 is a diagram showing an example of a harmonic superimposed voltage. As in FIG. 8, A is amplitude and B is bias. The state of FIG. 9(a) is a dipolar modulation system. From here, even if the superimposed voltage in FIG. 9 shifts from (a) to (b), the modulation method remains dipolar modulation when B>A/2. On the other hand, when the superimposed voltage in FIG. 9 shifts from (a) or (b) to B<A/2 as shown in (c), the modulation method switches to unipolar modulation. In this way, the switching of the modulation scheme is stopped in the state of B>A/2 shown in FIG. 9B, but the switching of the modulation scheme is stopped in the state of B<A/2 shown in FIG. Enforced by rules.

The control rule can be realized by a function such as comparing the value of B or A with a predetermined threshold to distinguish the states. More specifically, the microcomputer executes a corresponding program to implement the control rules. Alternatively, instead of a computer, it can be realized by an electronic circuit with equivalent functions. As an application example, when the command generator 105 in FIG. 1 acquires a speed signal of an electric train exceeding 30 km, it issues a command signal recognized as shown in FIG. 9(c) to switch the modulation method to unipolar modulation. Conversely, if it is less than 30 km, it is recognized as in FIG. 9(b), and the modulation method is maintained as dipolar modulation.

As described above, in the first embodiment, during polarity discrimination, the modulation rate calculated based on the voltage to be output is set so as not to exceed the threshold value at which the modulation method is switched and controlled between dipolar modulation and unipolar modulation. ing. Further, during polarity discrimination, control is performed to change the carrier frequency fc so as to maintain dipolar modulation. For example, for an electric train traveling at a speed of 20 km, the carrier frequency fc is adjusted to make up for the lack of performance caused by forcibly maintaining dipolar modulation, which is not optimal for an inverter, when determining polarity, although unipolar modulation is normally suitable. controlled to change.

FIG. 10 is a flow of modulation scheme determination when superimposing harmonics. When a predetermined amount of superimposition I* is superimposed, a voltage V* is output. From there, the modulation factor M* is calculated and the modulation scheme is determined. If the determined modulation method is dipolar modulation, the polarity discrimination is started as it is. If the modulation method is unipolar modulation, the carrier frequency fc is changed. The changed carrier frequency fc changes the output voltage V*.

FIG. 11 is a graph comparing changes in the d-axis current with FIG. 7 when the carrier frequency fc of Example 1 is changed. In FIG. 11, when the carrier frequency fc shown in graph 1 on the left side is decreased to the carrier frequency fc' shown in graph 2 on the right side, the PWM period becomes longer. As a result, the PWM half cycle (peak-valley cycle) dt becomes longer like the time width dt'. From the above equation (2), as the time width dt increases, the output voltage _V1 decreases.

As a result, the modulation rate Vc decreases according to the above equation (3), and the state described with reference to FIG. 9(b) is obtained. Therefore, the modulation mode can be maintained without exceeding the switching modulation rate of the modulation mode. As described above, the permanent magnet synchronous machine control apparatus according to the first embodiment of the present invention can stably perform polarity determination as opposed to the conventional polarity determination that is unstable due to the switching of the modulation method.

Next, Example 2 will be described with reference to FIGS. 12 and 13. FIG. In Example 2, unlike Example 1, the amount of superimposed harmonics is changed. The following description focuses on the differences from the first embodiment.

In Example 2, the modulation rate calculated based on the voltage output during polarity discrimination does not exceed the modulation rate of dipolar modulation, unipolar modulation, and the modulation scheme switching between them, and maintains dipolar modulation. change the amount of voltage superimposition. In this example, dipolar modulation is maintained, but unipolar modulation may be maintained instead.

FIG. 12 is a flow of modulation scheme determination when superimposing harmonics. When a predetermined amount of superimposition I* is superimposed, a voltage V* is output. From there, the modulation factor M* is calculated and the modulation scheme is determined. If the determined modulation method is dipolar modulation, the polarity discrimination is started as it is. When the modulation method is unipolar modulation, the amount of superimposition I* is changed. This exemplifies a case in which, at the time of polarity discrimination, settings are basically made to be unified to dipolar modulation.

FIG. 13 is a graph comparing changes in the d-axis current with FIG. 7 when the superposition amount is changed in Example 2. FIG. In FIG. 13, the voltage superposition amount V1* shown in (a) of graph 3 on the left side is reduced to the amount of voltage superimposition V1* shown in (a) of graph 4 on the right side. Then, the d-axis current in FIG.

At this time, as id becomes smaller, the output voltage _V1 becomes smaller according to the above equation (2). As a result, the modulation factor Vc decreases according to the above equation (3), and is set so as not to exceed the threshold value for switching and controlling the modulation method. Therefore, the modulation scheme can be maintained in this case as well. Control rules for realizing these can also be handled by a computer program. As described above, according to the second embodiment, a permanent magnet synchronous machine control device capable of stably determining polarity is realized.

A permanent magnet synchronous machine control device according to an embodiment of the present invention can be summarized as follows.
[1] As shown in FIG. 1, a permanent magnet synchronous machine control device having a power converter 102 that supplies drive power to a permanent magnet synchronous machine 103 and a controller 101 that controls the power converter 102 . The controller 101 includes a voltage command generation section, a current detection section 121, and a magnetic pole polarity determination section 201 (FIG. 3).

The voltage command generation unit is composed of most of the controller 101 shown in FIG. 1, and generates the output voltage _V1 by PWM control capable of superimposing harmonics. Although PWM is exemplified here, if it is possible to superimpose harmonics and give a command to generate a desired output voltage _V1 , it is not limited to PWM, and pulse frequency modulation (VFM) can be used. , or anything else.

Current detection unit 121 detects a current that flows according to output voltage _V1 applied from power converter 102 to permanent magnet synchronous machine 103 . The magnetic pole polarity determination unit 201 determines the magnetic pole polarity of the permanent magnet synchronous machine 103 based on the relationship between the amount of change in the current detected by the current detection unit 121 and the amount of change in the inductance value of the permanent magnet synchronous machine 103. .

The controller 101 can switch the PWM control modulation method capable of superimposing harmonics to the optimum modulation method according to the modulation rate Vc calculated using at least one of the output voltage _V1 and the frequency. Here, it is assumed that the modulation method is automatically switched according to the output voltage _V1 . As described above, in order to determine the pole polarity, an output voltage _V1 superimposed with an abrupt and fairly high voltage high frequency is applied.

These high voltage pulse impulses can cause controller 101 to switch to an unintended modulation scheme. Due to this, when the modulation method is automatically switched to the optimum method according to the output voltage _V1 , a vicious cycle occurs in which the magnetic pole polarity discrimination becomes erroneous if the output voltage _V1 changes.

Therefore, as shown in FIG. 9(b), the controller 101 makes a decision by classifying the cases, and the controller 101 stops the switching only when the magnetic pole polarity is decided when it is possible to switch to the optimum modulation method. As a result, a voltage error due to switching of the modulation method does not occur, and the polarity can be determined stably.

[2] In the permanent magnet synchronous machine control device of [1] above, as shown in FIG. It is preferable to determine the polarity by

In FIG. 7, when the voltage superposition command values shown in (a) to (e) are superimposed and the line voltage Vuv shown in (f) is applied to the permanent magnet synchronous machine 103, the d-axis current _id is Due to the influence of magnetic saturation, the pulsation waveform becomes asymmetric with respect to positive and negative as shown in FIG. 7(g). The asymmetry of this waveform can be used to determine the polarity of the magnetic pole. Determination of asymmetry can be handled by a control rule or the like that determines the difference obtained by subtracting the absolute values of the positive and negative values using a predetermined threshold value.

[3] In the permanent magnet synchronous machine control device of [1] or [2] above, instead of stopping the switching of the modulation method when the magnetic pole polarity is determined, the controller 101 changes the modulation method when the magnetic pole polarity is determined. is preferably set to a carrier frequency fc that can maintain . By executing the program of the control rule on the computer according to the procedure shown in the flow of FIG. 10, the voltage error due to the switching of the modulation method does not occur, and the polarity can be determined stably.

[4] In the permanent magnet synchronous machine control device of [1] or [2] above, the amount of superimposed harmonics I* is set so that the modulation method can be maintained during magnetic pole polarity discrimination. By executing the program of the control rule on the computer according to the procedure shown in the flow of FIG. 12, the voltage error due to the switching of the modulation method does not occur, and the polarity can be determined stably.

[5] As shown in FIG. 1, the power converter 102 in the permanent magnet synchronous machine control device of [1] or [2] above is preferably a three-level inverter. For the modulation method, for example, dipolar modulation and unipolar modulation are suitable for a 3-level inverter, and for example, sine wave modulation, two-phase modulation, and third harmonic addition modulation are suitable for a 2-level inverter. As a result, high performance can be achieved.

[6] In the permanent magnet synchronous machine control device of [1] or [2] above, as shown in FIG. 8, the controller 101 preferably maintains dipolar modulation during magnetic pole polarity discrimination. Dipolar modulation is suitable for the permanent magnet synchronous machine 103 when the frequency of the output voltage _V1 is low at startup or at low speed rotation. On the other hand, when the frequency of the output voltage _V1 is high at medium to high speed rotation, unipolar modulation is convenient, and the modulation method is often automatically switched and set accordingly.

In such a setting, when the permanent magnet synchronous machine 103 is started or rotated at a low speed, when a harmonic voltage is superimposed on the output voltage _V1 for magnetic pole polarity discrimination, the output voltage V It may be automatically switched to unipolar modulation by determining that the frequency of ₁ has increased.

There is a problem that the magnetic pole polarity discrimination is wrong due to the switching of the modulation method in this way. In order to prevent this, the controller 101 can accurately determine the magnetic pole polarity by maintaining dipolar modulation during the magnetic pole polarity determination. As a result, it becomes easier to avoid malfunctions such as reverse rotation at the time of start-up and during low-speed running, so that practicality for electric vehicles and the like is enhanced.

[7] In the permanent magnet synchronous machine control device of [1] or [2] above, the control rule shown in FIG. 9 can be set in any way by a computer program or the like. Therefore, the controller 101 may be set to maintain unipolar modulation during magnetic pole polarity discrimination. In this manner, by maintaining the modulation method regardless of the modulation method, the effect of making the magnetic pole polarity discrimination accurate can be obtained. In other words, such an application is also possible, and the range of application can be expanded.

Further, the permanent magnet synchronous machine control method according to the embodiment of the present invention (hereinafter referred to as "this method" or simply "method") can be summarized as follows.

[8] This method is a permanent magnet synchronous machine control method for driving and controlling the permanent magnet synchronous machine 103 by applying, for example, an output voltage generated by PWM control, which is capable of superimposing harmonics. The method has the following steps. First, the current flowing through the permanent magnet synchronous machine 103 to which the output voltage is applied is detected. The magnetic pole polarity of the permanent magnet synchronous machine 103 is determined based on the amount of change in the inductance value of the permanent magnet synchronous machine 103 with respect to the detected change in current.

In addition, for example, PWM control, which is capable of superimposing harmonics, is switched to a modulation method according to the modulation rate calculated from the output voltage, and the controller 101 superimposes the harmonic voltage on the output voltage When performing the magnetic pole polarity discrimination, the switching of the modulation method is stopped. As a result, the controller 101 fixes the switching of the modulation method by the threshold determination control and other control rules when the magnetic pole polarity is determined in the state shown in FIG. 9(b). That is, the switching is stopped. As a result, a voltage error due to switching of the modulation method does not occur, and the polarity can be determined stably.

[9] In the method [8] above, it is preferable to apply an AC voltage command in the magnetic pole direction of the permanent magnet synchronous machine 103 when the magnetic pole polarity is determined. As a result, the d-axis current _id is affected by magnetic saturation and becomes an asymmetric pulsating waveform with respect to positive and negative as shown in FIG. 7(g). The asymmetry of this waveform can be used to determine the polarity of the magnetic pole.

[10] In the above method [8] or [9], the controller 101 can maintain the modulation method during the magnetic pole polarity determination, instead of stopping the switching of the modulation method during the magnetic pole polarity determination. It is preferably set to the carrier frequency fc. As a result, by executing the control rule according to the procedure shown in the flow of FIG. 10, a voltage error due to switching of the modulation method does not occur, and the polarity can be determined stably.

[11] In the above method [8] or [9], it is preferable to set the harmonic superposition amount I* so that the modulation method can be maintained during magnetic pole polarity discrimination. As a result, by executing the control rule according to the procedure shown in the flow of FIG. 12, a voltage error due to switching of the modulation method does not occur, and the polarity can be determined stably.

[12] In the method of [8] or [9] above, it is preferable to use a three-level inverter. As a result, high performance can be achieved.
[13] In the above method [8] or [9], it is preferable to maintain dipolar modulation during magnetic pole polarity discrimination. As a result, it becomes easier to avoid malfunctions such as reverse rotation at the time of start-up and at low-speed running, so that practicality for electric vehicles and the like is enhanced.

[14] In the above method [8] or [9], it is preferable to maintain unipolar modulation during magnetic pole polarity discrimination. Since such applications are also possible, the range of application can be expanded.

Further, each of the configurations, functions, processing units, processing means, etc. described above may be realized by hardware, for example, by designing a part or all of them using an integrated circuit. The permanent magnet synchronous machine control device is configured by a computer (not shown). The computer includes, for example, a CPU (Central Processing Unit), a memory, a communication device, and an input/output device. The CPU implements the illustrated functions by executing programs stored in the memory. The memory of this computer also stores a DB containing formulas, thresholds, constants, and various other parameters. Information such as programs and tables that implement each function can be stored in recording devices such as memory, hard disks, SSDs (Solid State Drives), or recording media such as IC cards, SD cards, and DVDs. .

1 to 4 Graph 101 Controller 102 Power converter (3 level inverter)
103 Permanent magnet synchronous machine 105 Command generator 111 Vector control unit 112 Position/speed estimation calculation unit 113 Three-phase coordinate conversion unit 114, 703 dq coordinate conversion unit 115 PWM signal controller 116 Current detection unit 117 Superimposed voltage calculation unit 121 Phase current Detection unit 132 Main circuit unit 133 Gate driver 201 Magnetic pole polarity determination unit 202 Axis error estimation operation unit 203 Speed estimation operation unit 204 Position estimation operation unit 210 Inductance operation unit 211 First inductance operation unit 212 Second inductance operation unit 213 Third inductance calculation unit 214 Fourth inductance calculation unit 215 Polarity determination/reversal processing units 712 and 714 Switch 701 AC voltage component application unit 702 Superimposed voltage phase correction table 703 dq coordinate conversion units 711 and 713 AC waveform generator 801 , 802 adder 804, 805 multiplier

Claims (14)

A permanent magnet synchronous machine control device comprising: a power converter that supplies driving power to a permanent magnet synchronous machine; and a controller that controls the power converter,
The controller is
a voltage command generator capable of superimposing harmonics and generating an output voltage;
a current detection unit that detects current flowing between the power converter and the permanent magnet synchronous machine;
a magnetic pole polarity determination unit that determines the magnetic pole polarity of the permanent magnet synchronous machine based on the current detected by the current detection unit;
with
The controller switches the modulation method for superimposing the harmonics to a method according to the output voltage,
The controller stops switching the modulation method when the magnetic pole polarity is determined by superimposing the harmonic on the output voltage.
Permanent magnet synchronous machine controller. The magnetic pole polarity determination unit applies an AC voltage command in the magnetic pole direction of the permanent magnet synchronous machine when the magnetic pole polarity determination is performed.
The permanent magnet synchronous machine control device according to claim 1. The controller sets a carrier frequency that can maintain the modulation method instead of stopping the switching of the modulation method when the magnetic pole polarity is determined.
The permanent magnet synchronous machine control device according to claim 1 or 2. setting the amount of superimposed harmonics so that the modulation method can be maintained when the magnetic pole polarity is determined;
The permanent magnet synchronous machine control device according to claim 1 or 2. wherein the power converter is a 3-level inverter;
The permanent magnet synchronous machine control device according to claim 1 or 2. 3. The permanent magnet synchronous machine control device according to claim 1, wherein said controller maintains dipolar modulation during said magnetic pole polarity discrimination. 3. The permanent magnet synchronous machine control device according to claim 1, wherein said controller maintains unipolar modulation during said magnetic pole polarity discrimination. A permanent magnet synchronous machine control method capable of superimposing harmonics and controlling to apply the generated output voltage to the permanent magnet synchronous machine,
detecting a current flowing through the permanent magnet synchronous machine to which the output voltage is applied;
determining the magnetic pole polarity of the permanent magnet synchronous machine based on the detected current;
The modulation method for superimposing the harmonics is switched according to the modulation rate calculated from the output voltage, and when the magnetic pole polarity is determined by superimposing the harmonic voltage on the output voltage, the modulation method stop switching,
Permanent magnet synchronous machine control method. applying an AC voltage command in the magnetic pole direction of the permanent magnet synchronous machine when the magnetic pole polarity is determined;
The permanent magnet synchronous machine control method according to claim 8. setting a carrier frequency that can maintain the modulation method instead of stopping switching the modulation method when the magnetic pole polarity is determined;
The permanent magnet synchronous machine control method according to claim 8 or 9. setting the amount of superimposed harmonics so that the modulation method can be maintained when the magnetic pole polarity is determined;
The permanent magnet synchronous machine control method according to claim 8 or 9. using a three-level inverter,
The permanent magnet synchronous machine control method according to claim 8 or 9. maintaining dipolar modulation during the magnetic pole polarity determination;
The permanent magnet synchronous machine control method according to claim 8 or 9. maintaining unipolar modulation during the magnetic pole polarity determination;
The permanent magnet synchronous machine control method according to claim 8 or 9.