JP5576039B2 - Synchronous motor controller - Google Patents

Description

  The present invention relates to a synchronous motor control device, and more particularly to a technique for controlling an input current of a synchronous motor.

  As a conventional technique for determining a d-axis current with respect to the speed of field-weakening control in a synchronous motor control device related to the present invention, for example, Japanese Patent Application Laid-Open No. 2006-20397 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2000-228892 ( Patent Document 2) and Japanese Patent Application Laid-Open No. 2008-141824 (Patent Document 3).

Japanese Patent Laid-Open No. 2006-20397 JP 2000-228892 A JP 2008-141824 A

  In the technique disclosed in Patent Document 1, the d-axis current component with respect to speed is determined by multiplying the speed difference between the actual motor speed and the reference speed (base speed) at which reactive current starts to flow by the speed-dependent proportional coefficient of reactive current, Furthermore, the d-axis current characteristic with respect to the voltage is changed by multiplying the difference between the measured voltage and the reference voltage by a voltage-dependent proportional coefficient and changing the reference speed at which the field weakening is started. The current characteristics remain constant.

  In the technique disclosed in Patent Document 2, there is a method in which the characteristics of the current command value are tabulated for all speed, torque, and voltage operation regions and the characteristics are determined. In addition, man-hours are required for characteristic analysis and setting of the entire operation area, and a data area for storing the operation area setting is also required.

  Further, as shown in Patent Document 3 as the second embodiment, there is a method of using both components as an operation method in which the field weakening control and the maximum torque control are used in combination. In the vicinity, the d-axis current also tends to be excessive due to field-weakening control.

  In order to solve these problems, the object of the present invention is to combine the d-axis current characteristic with respect to the speed and voltage and the d-axis current characteristic with respect to the torque current in a no-load state to synthesize the d-axis current characteristic. Another object of the present invention is to provide a synchronous motor control device capable of setting operating characteristics more easily than in the past.

In solving the above problems, the present invention provides a current control device that detects the current of a synchronous motor and controls the current by dividing the current into two d-axis d-axis currents and d-axis current orthogonal components. The d-axis current command value 1 for speed and voltage and the d-axis current command value 2 for generating the maximum torque are synthesized to achieve high rotation by field weakening control, and the final d-axis current control is performed. In the synchronous motor control device as the d-axis current command value of the part,
A d-axis current characteristic by the field-weakening control, a storage unit for holding the d-axis current characteristic for generating the maximum torque, and a d-axis current command value 1 and 2 based on both characteristics are combined to obtain a final d A current command synthesis processing unit that outputs an axis current command value is provided.

  Further, according to the present invention, in the synchronous motor control device described above, the current command synthesis processing unit compares the magnitudes of the d-axis current command values 1 and 2 based on both the d-axis current characteristics, and determines the maximum value. The final d-axis current command value is output.

  Further, according to the present invention, in the synchronous motor control device described above, the current command synthesis processing unit adds the magnitudes of the d-axis current command values 1 and 2 based on the both d-axis current characteristics to obtain a final d It is output as a shaft current command value.

The present invention also includes a current control device that detects the current of the synchronous motor and divides the current into two orthogonal components of the d-axis d-axis current and the q-axis current, and controls the current by high field-weakening control. The d-axis current command value 1 for speed and voltage for rotation and the d-axis current command value 2 for generating the maximum torque are synthesized, and the final d-axis current command of the d-axis current control unit is synthesized. In the synchronous motor control device as a value,
A d-axis current command value corresponding to speed and voltage at no load is set as the d-axis current command value 1 and is combined with the d-axis current command 2 to output a final d-axis current command value. It is characterized by a command.

  Further, according to the present invention, in the synchronous motor control device described above, the current command synthesis processing unit compares the magnitudes of the d-axis current command values 1 and 2 and determines the maximum value as a final d-axis current command. It is output as a value.

  In the synchronous motor control device according to the present invention, the current command synthesis processing unit adds the magnitudes of both the d-axis current command values 1 and 2, and outputs the result as a final d-axis current command value. It is characterized by doing.

  Further, according to the present invention, in the synchronous motor control device described above, the voltage value used when calculating the d-axis current command value 1 is changed according to the magnitude of the torque current, and current characteristics with respect to speed and voltage are changed. A reference voltage adjusting unit for adjusting the frequency is provided.

  In the synchronous motor control device according to the present invention, the reference voltage adjustment unit uses a value obtained by subtracting an adjustment value proportional to the torque current from the detected voltage when calculating the d-axis current command value 1. It is characterized by the voltage value to be used.

  Further, according to the present invention, in current control of a synchronous motor, a d-axis current command for speed and voltage at no load is obtained. For example, current command characteristics at no load are prepared for several types of voltages within the voltage use range, and the characteristics are switched according to the voltage to obtain the d-axis current command idn according to the detection speed and the detected voltage. On the other hand, for the output torque, for example, the d-axis current command idt is calculated from the current command characteristic set based on the maximum torque control. By combining a current command idn for speed and voltage with a current command idt for torque, a d-axis current command value as a final output is obtained.

  In addition to the method of adding and outputting the d-axis current command values idt and idn, a method of outputting the maximum value component of idt and idn can be selected. The d-axis current characteristics at no load with respect to speed and voltage, and for example, the data area necessary for setting the d-axis current characteristics with respect to torque are set at 3 points, respectively, so the number of data is small and easier than before. The operation characteristics of the d-axis current command can be set. Furthermore, by changing the voltage value referred to in the current command characteristic according to the torque, it is possible to change the d-axis current command and prevent the d-axis current from becoming excessive at no load at high rotation. To do.

  According to the present invention, when determining a d-axis current command in field-weakening control, it is possible to easily set operation characteristics of the d-axis current command with respect to speed, voltage, and torque. In addition, since the number of tables required for setting can be reduced, the apparatus can be reduced in size and price.

FIG. 1 is a configuration example of a current command converter 100 which is a main current control block of a d-axis current control apparatus for carrying out the present invention. The d-axis current calculation unit 1 using field weakening control obtains the d-axis current command idn * (d-axis current command value 1) for the current speed N and the voltage Vdc, and the current command characteristic set based on the maximum torque control is obtained. After obtaining the d-axis current command idt * (d-axis current command value 2) for the q-axis current command value iq * by the d-axis current calculation unit 2, the final d-axis current is obtained via the current command synthesis processing unit 3. Outputs command id *.

  FIG. 2 is a configuration example of a speed control system for carrying out the present invention in the synchronous motor control device.

101 is a permanent magnet synchronous motor, 102 is a position detector that detects the rotational position of a rotor (not shown) of the motor 101, and 103 is a rotational speed N of the rotor of the synchronous motor from the output of the position detector 102. A speed calculator 104 calculates and outputs a q-axis current command value iq * from a deviation between the current rotational speed N of the rotor obtained from the speed calculator 103 and a preset speed command value N *. speed control calculator, 100 is based on the q-axis current command value iq *, d-axis current command value id * and the q-axis current command value current command converter iq * is calculated, is 106, the current detector 105 UVW / d-q converter 107 that inputs U-phase current value Iu, V-phase current value Iv, and W-phase current value Iw detected by, and converts them into q-axis current value Iq and d-axis current value Id, d-axis current that calculates the d-axis voltage by inputting the current value obtained by subtracting the d-axis current value Id from the d-axis current command value id * The control unit 108 receives a current value obtained by subtracting the q-axis current value Iq from the q-axis current command value Iq *, and calculates a q-axis voltage. 109 includes a d-axis and a q-axis. A dq / UVW converter 110 for converting the voltage of the three-phase AC voltage into a three-phase AC voltage, 110 is a PWM converter for converting the three-phase AC voltage into a PWM waveform.

  Reference numeral 112 denotes a rectifier circuit that converts a commercial three-phase AC voltage 111 into a DC voltage Vdc. Reference numeral 113 denotes an inverter that is driven by a PWM waveform voltage command from the PWM converter 110 and outputs a three-phase AC. The phase alternating current is supplied to the permanent magnet synchronous motor 101.

  In the above configuration, the operation is as follows.

The q-axis current command value iq * is calculated by the speed control calculator 104 from the deviation between the current speed N of the permanent magnet synchronous motor and the speed command value N *. Then from this q-axis current command value iq * and the current speed N, d-axis current command value id * by the current command converter 100, and the q-axis current command value iq * is obtained. The U-phase current value Iu, the V-phase current value Iv, and the W-phase current value Iw detected by the current detectors 105 for the three phases are input to the UVW / d-q converter 106, where d An axis current value Id and a q axis current value Iq are obtained. This d-axis current value Id is subtracted from the d-axis current command value Id *, and the subtraction result is input to the d-axis current control calculator 107. On the other hand, the q-axis current value Iq is subtracted from the q-axis current command value iq *, and the subtraction result is input to the q-axis current control calculator 108.

  Here, the current value detected from the three-phase current detector 105 is inputted to the UVW / d-q converter 106, and this is detected by detecting only the current of only two phases, for example, the U phase and the W phase. The V-phase current value Iv may be calculated as Iv = −Iu−Iw.

  The calculation result of the voltage calculated by the d current control calculator 107 and the q current control calculator 108 is converted into a three-phase AC voltage by the dq / UVW converter 109, and further, a PWM wave voltage command is output by the PWM converter 110. And supplied to the inverter 113. On the other hand, the DC voltage Vdc converted from the three-phase AC voltage 111 in the rectifier circuit 112 is supplied to the inverter 113 as a power source. The inverter 113 outputs a three-phase AC based on the voltage command of the PWM wave, and the permanent voltage The magnet synchronous motor 101 is supplied.

Next, a specific configuration example of the current command converter 100 which is a d-axis current control block is shown in FIG. The current calculation unit 4 (corresponding to 1 in FIG. 1) for field weakening control has three current command characteristics at the time of no load (torque 0) at a plurality of voltages (Vdc), that is, current command characteristics 5-7. Map (table) 1 to map 3 are provided as storage units. In addition, the main circuit voltage comparison unit 8 that switches and selects the current command characteristic to be used with reference to the detection voltage Vdc, and two types of current command characteristics selected based on the detection voltage Vdc are detected as a voltage between two points. An interpolation processing unit 9 is provided that calculates an d-axis current command idn ^* (d-axis current command value 1) when there is no load with respect to the detection speed N and the detection voltage Vdc by performing an interpolation calculation based on a voltage ratio to the voltage. In FIG. 5, the main circuit voltage comparison unit 8 is connected to the contact 8a, the current command characteristics 5 and 6 are selected, and the interpolation processing unit 9 determines the voltage ratio between the two voltages from the two characteristics and the detected voltage. To calculate the d-axis current command idn ^{* when} there is no load.

  Specifically, map1 (id, N), map2 (id, N), and map3 (id, N) corresponding to the current command characteristics 5 to 7 are the characteristics when the main circuit voltages are Vdc1, Vdc2, and Vdc3, respectively. 6 (1), FIG. 6 (2), and FIG. 6 (3) are prepared. Note that the number of types of current command characteristics is not necessarily three.

Further, with reference to the q-axis current command value iq ^* , a map () of a d-axis current command characteristic 10 (corresponding to 2 in FIG. 1) that outputs a d-axis current command idt ^* (d-axis current command value 2) with respect to the output torque. id, iq). For example, when the setting of the current command characteristic 10 is set as a condition satisfying the maximum torque control by linear approximation as in Document 3, the characteristic of the d-axis current command idt ^* with respect to the torque current is shown as in FIG.

Current command idn for these speed N and the voltage Vdc ^*, the current command idt ^* is with respect to the torque, the current command synthesis processing unit 11 (corresponding to 3 in FIG. 1), the d-axis current command value Id ^* by being added decide. The current command synthesis processor that performs this addition function is shown as 3a in FIG. As described above, the characteristics of the entire region with respect to the speed N and the torque T can be obtained.

The characteristic obtained by the addition synthesis in the current command synthesis processing unit 3a of FIG. 3 is shown as the d-axis current command characteristic in FIG. 8 as the addition synthesis of FIGS. In FIG. 8, the vertical axis represents the added value Id ^* (idn + idt) of the current command for the voltage and the current command for the torque, and the horizontal axis represents the speed (N).

Next, Example 2 will be described. In the present embodiment, in the current control block diagram of FIG. 5, the d-axis current command idn ^{* is} passed through the current command characteristics 5 to 7, the main circuit voltage comparison unit 8 and the interpolation processing unit 9 as in the first embodiment ^. And the d-axis current command idt ^* is similarly calculated from the d-axis current command characteristic 10.

The difference from the first embodiment is that the current command synthesis processing unit 11 is configured as indicated by 3b in FIG. The composite processing unit 3b in FIG. 4 determines the d-axis current command id ^* used for output by comparing the magnitudes of the d-axis current commands idn ^* and idt ^* and selecting a component having a large command value. FIG. 9 shows an example of the d-axis current command characteristic after the combination of FIGS. 6 and 7 in the case of the second embodiment. In this case, the d-axis current value in the high speed region can be suppressed as compared with the case of adding idn ^* and idt ^* .

  Next, Example 3 will be described. As in the first embodiment, the d-axis current characteristic with respect to the speed operates based on the current characteristic set by the field weakening control, and as long as the main circuit voltage operates at a constant level, the reference characteristic at no load is obtained. As shown in FIG. 8, the speed corresponding to the break point is constant regardless of the load state. For this reason, when it is set according to the characteristics in the high load region, the d-axis current command tends to be larger than necessary with respect to the motor characteristics in the region where the torque is high and the torque is low.

In order to cope with this, as shown in FIG. 10, a reference voltage adjustment unit 12 is provided before the main circuit voltage comparison unit 8, and the reference voltage adjustment is performed based on the q-axis current command value iq ^* and the main circuit detection voltage Vdc. After calculating the reference voltage value Vdc1 in the unit 12, the characteristics of the d-axis current command id ^* are made variable according to the torque by using the current command characteristics 5 to 7, and d at high speed and low load. The shaft current command can be reduced.

That is, the voltage value used when calculating the d-axis current command id ^* is changed according to the magnitude of the torque current, and the current characteristics with respect to speed and voltage are adjusted as the torque current increases even with the same voltage value. It is characterized by.

The voltage detection value adjustment unit 12 in FIG. 10 uses a proportional coefficient Kv for torque based on the main circuit voltage Vdc and the q-axis current command value iq ^* ,
Vdc1 = Vdc−Kv × iq ^*・ ・ ・ (Formula 1)
Thus, the voltage detection value Vdc1 obtained by reducing the voltage detection value Vdc is calculated. The main circuit voltage comparison unit 8 refers to the voltage Vdc1 and obtains the d-axis current command idn ^* via the current command characteristics 5 to 7 and the interpolation processing unit 9. That is, by subtracting the adjustment value proportional to the torque current from the detected voltage when changing the voltage value, the voltage value used in calculating the d-axis current command id ^* is calculated to adjust the current characteristics. Features.

Thereafter, the d-axis current idt ^* with respect to the torque is obtained in the same manner as in the first embodiment, and the d-axis current command idn ^* and the d-axis current idt ^* are added in the synthesis processing unit 11 and used for the control calculation. D-axis current command id ^* to be calculated. FIG. 11 shows an example of the d-axis current characteristic after synthesis in the case of the third embodiment.

  As described above, the present invention sets the reference characteristics for the speed and voltage in the no-load torque, and determines the torque component by combining with the maximum torque control, thereby setting and calculating the d-axis current command value. Simplify. The combination of the maximum torque control component and the field weakening control component and the use of the maximum value of each component can be selected, and the d-axis current command value is obtained. Also, by making the voltage value when referring to the current command characteristic variable according to the output torque, the d value at high speed and low torque is higher than when the maximum torque component idt is added to the field weakening component idw of the d-axis current command. It is possible to reduce the shaft current.

The block diagram of the current command converter of an Example of this invention. The block diagram of a synchronous motor control apparatus similarly. Explanatory drawing of the synthetic | combination process part of d-axis current characteristic similarly. Explanatory drawing of the synthetic | combination process part of d-axis current characteristic similarly. The block diagram of the current command converter of Example 1 of the present invention. Explanatory drawing of d-axis current command characteristics with respect to speed and voltage when no load is applied. Explanatory drawing of the d-axis current command characteristic with respect to torque current. Explanatory drawing of the d-axis current command characteristic which similarly synthesize | combined the characteristic. Explanatory drawing of the d-axis current command characteristic which synthesize | combined the characteristic of this invention Example 2. FIG. The block diagram of the electric current command converter which added the reference voltage adjustment part of this invention Example 3. FIG. Explanatory drawing of d-axis current command characteristic similarly.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... d-axis current calculation part by field weakening control, 2 ... d-axis current calculation part with respect to a torque component, 3 ... Current command synthetic | combination process part, 3a ... Current command synthetic | combination process part (in the case of addition process), 3b ... Current command synthetic | combination process 4 (current value calculation unit for field weakening control) 5 ... d-axis current command characteristic for speed at voltage Vdc1, 6 ... d-axis current command characteristic for speed at voltage Vdc2, 7 ... at voltage Vdc3 D-axis current command characteristic for speed, 8 ... main circuit voltage comparison unit, 9 ... current command value interpolation processing unit, 10 ... d-axis current command characteristic for torque, 11 ... current command synthesis processing unit, 12 ... reference voltage adjustment unit, DESCRIPTION OF SYMBOLS 100 ... Current command converter, 101 ... Permanent magnet synchronous motor, 102 ... Position detector, 103 ... Speed calculator, 104 ... Speed control calculator, 105 ... Current detector, 106 ... UVW / dq converter, 10 ... d-axis current control calculator 108 ... q-axis current control calculator 109 ... dq / UVW converter 110 ... PWM converter 111 ... three-phase AC voltage 112 ... rectifier circuit 113 ... inverter unit map map 1-3... storage unit.

Claims (5)

It has a current control device that detects the current of the synchronous motor driven by the inverter and controls this current by dividing the current into two d-axis currents of the dq axis and the orthogonal component of the q-axis current. The d-axis current command value 1 for speed and voltage and the d-axis current command value 2 for generating the maximum torque are combined to achieve the final d-axis current command value of the d-axis current control unit. In the synchronous motor control device
A table 1 of no-load current command characteristics for a plurality of voltages is selected, and two tables are selected from the table 1 based on a detected DC voltage (Vdc) that is a detected value of an input DC voltage of the inverter , Each DC voltage (Vdc1 to 3) that defines a plurality of tables (map1 to 3), and a voltage ratio between a voltage between each DC voltage that defines the two selected tables and the detected DC voltage To calculate the d-axis current command value 1 when there is no load with respect to the detection speed and the detection DC voltage,
a current command characteristic table 2 obtained from the q-axis current command value, and the d-axis current command value 2 is calculated from the current command characteristic selected from the table 2 according to the q-axis current command value;
A synchronous motor control device comprising a current command synthesis processing unit that synthesizes the d-axis current command value 1 and the d-axis current command value 2 and outputs a final d-axis current command value. In the synchronous motor control device according to claim 1,
The synchronous motor control device, wherein the current command synthesis processing unit compares the magnitudes of the d-axis current command values 1 and 2 and outputs the maximum value as a final d-axis current command value. In the synchronous motor control device according to claim 1,
The synchronous motor control device, wherein the current command synthesis processing unit adds the magnitudes of the two d-axis current command values 1 and 2 and outputs the result as a final d-axis current command value. In the synchronous motor control device according to any one of claims 1 to 3,
The detected DC voltage and change the speed, voltage synchronous motor control device is characterized by providing a reference voltage adjusting unit for adjusting the current characteristics for according to the magnitude of the q-axis current command value. In the synchronous motor control device according to claim 4,
The synchronous motor control device, wherein the reference voltage adjustment unit performs the change by subtracting an adjustment value proportional to a q-axis current command value from the detected DC voltage.

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