JP4771126B2 - Synchronous motor drive - Google Patents

Description

  The present invention relates to a synchronous motor driving device that drives a synchronous motor having an incremental type pulse generator (hereinafter abbreviated as PG) at a variable speed.

When driving a synchronous motor, the magnetic pole position is unknown to the drive device when the power is turned on, but if you try to drive with the magnetic pole position unknown, depending on the deviation of the magnetic pole position, it may not start due to insufficient torque, There is a risk of rotating in the opposite direction.
Therefore, conventionally, when driving a synchronous motor, an absolute type PG is combined with the synchronous motor, and the origin of the PG and the phase angle of the magnetic pole position are stored in advance in the drive device by the first operation. In general, after that, even when the power is once turned off and then turned on again, it is general that the magnetic pole position can be reliably restored by the position information from the PG.

  There are absolute type PGs that can detect only a rough position, and those that can detect even a fine position, but it is possible to estimate the position of the magnetic pole by taking these absolute position information into the drive device. The motor will not run away due to insufficient torque or reverse rotation.

  On the other hand, in order to drive a synchronous motor that combines an incremental type PG that is generally less expensive than an absolute type PG and that detects the rotational position by counting the number of pulses output according to the rotational displacement of the shaft. Several methods of driving a synchronous motor that estimate the magnetic pole position when the power is turned on have been proposed.

For example, the method described in Non-Patent Document 1 is a method of estimating the magnetic pole position from the current response to the voltage vector applied in the d-axis direction by utilizing the fact that the current response changes due to the magnetic saturation of the armature core. is there.
In this method, the voltage vector is determined in advance so that the current deviation at each position can be found without rotating the shaft at the time of magnetic pole position estimation, and the voltage vector is applied accordingly at the time of magnetic pole position estimation. The magnetic pole position is estimated using current feedback.

  In the sensorless control system of the permanent magnet type synchronous motor described in Patent Document 1, a magnetic pole position estimation method using a change in current response due to magnetic saturation of the armature core is also disclosed.

Koji Tanaka, Taro Moriyama, Ichiro Miki, “Initial magnetic pole position estimation method for interior permanent magnet synchronous motor using optimal voltage vector”, IEICE Transactions D, Vol. 124, No. 1, 2004, P.101-107 JP 2000-31493 A (paragraphs [0018] to [0023] etc.)

However, when the magnetic pole position is actually estimated by the method described in each of the above documents, depending on the motor, there may be a characteristic that magnetic saturation is difficult due to the magnetization characteristic of the armature core. Since the difference in current amplitude between the magnetic pole position and its position 180 ° (electrical angle, the same applies hereinafter) is small, it may be erroneously estimated by 180 °.
In addition, the difference in current amplitude detected by magnetic saturation is small relative to the resolution and detection accuracy of a microcomputer generally combined with a current detector and an A / D converter, and there is a possibility that it cannot be accurately estimated due to the influence. .

  SUMMARY OF THE INVENTION An object of the present invention is to provide a synchronous motor drive device that improves the estimation accuracy of the magnetic pole position by giving an optimum voltage command value even to a synchronous motor that is not easily magnetically saturated.

In order to solve the above-mentioned problem, the invention described in claim 1 is a drive device for a synchronous motor that drives a synchronous motor having an incremental type PG at a variable speed by an inverter unit,
Speed setting means for giving a speed command value of the synchronous motor, position / speed detection means for detecting the position and speed of the rotor based on the output pulse of the PG, and speed detection value output from the position / speed detection means And a speed adjusting means for generating a torque command value so that there is no deviation between the speed command value, a q-axis current command means for generating a q-axis current command value in a direction orthogonal to the magnetic pole position from the torque command value, A d-axis current command means for generating a d-axis current command value in the same direction as the magnetic pole position, a phase angle calculation means for calculating a phase angle based on a position detection value output from the position / velocity detection means, and an electric motor Current detection means for detecting current; first vector rotation means for decomposing the motor current into d-axis current and q-axis current using the phase angle; deviation between d-axis current and d-axis current command value; q Axial current and q-axis A d-axis current adjustment unit and a q-axis current adjustment unit that respectively generate a d-axis voltage command value and a q-axis voltage command value so that there is no deviation from the current command value; A synchronous motor comprising: a second vector rotating unit that converts a q-axis voltage command value into a three-phase AC voltage command; and a control unit that generates a drive pulse for the switching element of the inverter unit according to the three-phase voltage command In the drive device,
Means for outputting a voltage command value corresponding to a normalized primary resistance value as a constant of the synchronous motor, means for generating a d-axis voltage command value for magnetic pole position estimation by superimposing a high frequency signal on the voltage command value, and a first The high-frequency component detection means for detecting the high-frequency component of the detected d-axis current value output from the vector rotation means, and the magnetic pole position estimation based on the amplitude of the high-frequency component detected by the high-frequency component detection means The d-axis voltage command value is supplied to the second vector rotating means instead of the d-axis voltage command value from the d-axis current adjusting means, and the electrical angle for outputting the magnetic pole position estimation d-axis voltage command value is determined. And a phase angle calculation / switching unit that calculates a phase angle for applying the phase angle to the second vector rotation unit instead of the phase angle from the phase angle calculation unit, and
The true magnetic pole position is estimated from the phase angle at which the amplitude of the high frequency component detected by the high frequency component detecting means is maximized.

  According to the present invention, in the magnetic pole position estimation operation required every time the power is turned on when using an incremental type PG, a voltage command value (direct current) corresponding to a standardized primary resistance value, which is a motor constant used for motor control. By generating a magnetic pole position estimation d-axis voltage command value by superimposing the high-frequency component on the voltage), the synchronous motor is surely brought into a magnetic saturation state, and the amplitude of the high-frequency component of the d-axis current is set to the true magnetic pole position The true magnetic pole position can be estimated using the fact that it appears greatly only when approaching. For this reason, there are detection errors and calculation errors in the current detector, the A / D converter, and the microcomputer, and even when these precisions and resolutions are limited, it is possible to estimate the magnetic pole position without making a large error.

  The motor constant for obtaining the normalized primary resistance value is also necessary for normal vector control. If the constant is known in the synchronous motor, it is manually operated. It can be set using the electrical constant auto-tuning function. Therefore, there is no need to measure again for estimating the magnetic pole position.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall configuration diagram of this embodiment. In the main circuit, 100 is a three-phase AC power source, 200 is a diode rectifier, 300 is a smoothing capacitor, 400 is an inverter unit, and 500 is a synchronous motor. Reference numeral 2 denotes an incremental type PG attached to the synchronous motor 500, which can output a two-phase signal having a phase difference of 90 ° and a single rotation signal pulse.

Next, the structure of the drive device according to the present embodiment will be described together with the operation.
In FIG. 1, 1 is a speed setting device that gives a speed command value, 3 is a position / speed detector that converts the output pulse of PG2 into position and speed information, and 4 is a speed setting value N ^* and position from the speed setting device 1. A speed adjuster that outputs a torque command value by performing an adjustment operation so that there is no deviation from the speed detection value N from the speed detector 3, and an axis (hereinafter referred to as q-axis) where the torque command value is orthogonal to the magnetic pole position. ) Direction q-axis current command value i _q ^* converted to output q-axis current command device, 6 is an axis parallel to the magnetic pole position of the synchronous motor based on the position detection value from the position / speed detector 3 , D-axis) direction d-axis current command device for generating a d-axis current command value i _d ^* , 7 is a current detector for detecting the motor current, 8 is based on the position detection value from the position / speed detector 3 Phase angle calculator to obtain phase angle for vector decomposition of motor current 9 deviation of the current by the phase angle d-axis current i _d and the q-axis current i a first vector rotator decomposed into _q, 10 and d-axis current command value i _d ^* and the d-axis current detection value i _d The d-axis current regulator 11 performs an adjusting operation so as to eliminate the d-axis and outputs a d-axis voltage command value, and the adjusting operation 11 causes the deviation between the q-axis current command value i _q ^* and the q-axis current detected value i _q to disappear. A q-axis current regulator that outputs a q-axis voltage command value, 12 is a second vector rotator that converts each of the d-axis and q-axis voltage command values into a three-phase AC voltage command value, and 13 is a three-phase An inverter control circuit that performs pulse width modulation (PWM) control according to the voltage command value and generates a switching pattern to be applied to the semiconductor switching element of the inverter 400 unit, and 14 is an operating device for inputting an electric constant of the motor used for the control , 15 is a controller A storage device for storing electrical constants input by 4.
About each component mentioned above, except PG2 being an incremental type, there is no place different from a general synchronous motor drive device.

Now, 16 is a high frequency oscillator. In the present embodiment, when the magnetic pole position is estimated, the adder 19 adds a high frequency to the voltage command value corresponding to the normalized primary resistance value (% R: percent resistance) of the synchronous motor 500 stored in the storage device 15. A high-frequency signal output from the oscillator 16 is superimposed to generate a magnetic pole position estimation d-axis voltage command value.
Here, the normalized primary resistance value described above is given by Equation 1.
[Formula 1]
% R = (primary resistance value [Ω] + wiring cable resistance value [Ω]) × motor rated current [A] / (motor rated voltage [V] / √3) × 100 [%]

Further, 17 is a high-frequency component detector for detecting a high frequency component of the d-axis current detection value i _d, and its output is input to the phase angle calculation and the switching device 18. The phase angle calculation-switch 18, in response to a result of comparison of the amplitudes of the high frequency component obtained so far of the high frequency component of the detected by the high-frequency component detector 17 d-axis current detection value i _d, vector The phase angle to be input to the rotator 12 is calculated and switched, and the magnetic pole position estimation d-axis voltage command value v _d ^* ′ superimposed with the high frequency by the high frequency oscillator 16 and the phase angle calculation In order to input the phase angle output from the switch 18 to the vector rotator 12, it has a function of operating the switches 20 and 21.
That is, during the magnetic pole position estimation operation immediately after the power is turned on, the magnetic pole position estimation d-axis voltage command value v _d ^* ′ and q-axis voltage command value v _q ^* (= zero) output from the adder 19 by the changeover switch 20. ) To the vector rotator 12 and the selector switch 21 operates to switch the phase angle input to the vector rotator 12 from the phase angle calculator 8 to the phase angle calculator / switcher 18 side.

Next, the principle of estimating the magnetic pole position in this embodiment will be described.
As described in the above-mentioned documents, general synchronous motors have a magnetic saturation characteristic. When a voltage is applied in the direction of increasing magnetism, the magnetic flux is saturated and the inductance decreases, so the current changes greatly. To do. Conversely, when a voltage is applied in the direction of demagnetization, the inductance hardly changes, and the generation of current becomes smaller than when the magnetization is increased. The degree of magnetic saturation changes depending on the magnetic pole position of the synchronous motor.

Using this characteristic, in this embodiment, when estimating the magnetic pole position immediately after the power is turned on, as shown in FIG. 2, the d-axis voltage command value (DC voltage) corresponding to the normalized primary resistance value is set by the high frequency oscillator 16. A magnetic pole position estimation d-axis voltage command value v _d ^{* formed} by superposing a high-frequency signal (alternating voltage) is input to the vector rotator 12 via the changeover switch 20. Further, the amplitude of the high frequency component of the d-axis current generated thereby is measured by the high frequency component detector 17.
Here, the relationship between the estimated magnetic pole position and the high-frequency component of the d-axis current is as shown in FIG. 3, and the amplitude of the high-frequency component appears larger as it approaches the true value of the magnetic pole position. The true magnetic pole position can be estimated by detecting the position where the amplitude of the high frequency component becomes maximum.

The phase angle calculator / switcher 18 switches the phase angle so that the amplitude of the high-frequency component of the d-axis current is increased, so that the finally converged phase angle becomes the magnetic pole position estimated value.
As the phase angle (electrical angle data) output from the phase angle calculator / switcher 18, first, 360 ° is divided into four and changed in the order of 0 °, 180 °, 90 °, 270 ° every 90 °, In each case, the amplitude of the high frequency component of the detected d-axis current is compared and narrowed down to an angle range in which the amplitude becomes larger. In the example of FIG. 2, an angle range of 180 ° to 270 ° is selected.

Next, in the above angle range (180 ° to 270 °), 90 ° is divided into 42.5 in order of 202.5 °, 225 °,... Every 22.5 °. The amplitudes of the components are compared and narrowed down to an angle range in which the amplitude becomes larger.
Further, in the narrowed angle range, 22.5 ° is divided into a plurality of angle ranges, and the operation of repeating the narrowing until the final angle range is 0.7 ° is executed three times, and the average value is taken. The phase angle that finally converges is obtained. Here, the reason why the average value for three times is taken is to reduce the influence of detection error and the like by the current detector 7.
FIG. 4 is a diagram showing the concept of narrowing the angle range in order to detect the true value of the magnetic pole position, and the angles 22.5 ° and 0.7 ° in (b) and (c) are exaggerated. It is expressed as

FIG. 5 shows a high frequency of the d-axis current with respect to each phase angle (magnetic pole position) when the normalized primary resistance value (% R) in FIG. The amplitude value of the component is shown.
As can be seen from FIG. 5, when the normalized primary resistance value is small, the difference in amplitude value from the other positions is small in the vicinity of the true magnetic pole position (56.8 °), and it is shifted by 180 °. Since the difference from the amplitude value at the position is also small, when this difference is detected by a detection circuit using a combination of a current detector, an A / D converter and a microcomputer, it is erroneously determined whether the difference has increased, and the magnetic pole position is There is a possibility of convergence at a position shifted from the value. As a result, the magnetic pole position may be estimated incorrectly.

  Therefore, in order to make the estimation accuracy of the magnetic pole position as high as possible, the normalized primary resistance value can be set in advance so that the amplitude of the high-frequency component of the d-axis current is as large as possible without exceeding the current capacity of the driving device. is necessary. This normalized primary resistance value is one of the motor constants necessary for vector control of the synchronous motor. If the constant is known, it is set manually, and if it is not known, the control circuit has an electrical constant. What is necessary is just to set using an auto-tuning function etc., and since it does not need to measure and calculate in order to estimate a magnetic pole position, it does not become a burden for a user.

  As described above, according to the present embodiment, when estimating the magnetic pole position, a synchronous motor is used by using a d-axis voltage command value obtained by superimposing a high-frequency component on a standardized primary resistance value having a predetermined magnitude. Can be reliably magnetically saturated, and the magnetic pole position can be reliably estimated from the amplitude of the high-frequency component of the d-axis current at that time.

It is a block diagram which shows embodiment of this invention. It is explanatory drawing of magnetic pole position estimation operation | movement. It is a figure which shows the relationship between an estimated magnetic pole position and the amplitude of the high frequency component of d-axis current. It is a figure which shows the concept which narrows down an angle range in order to detect the true value of a magnetic pole position. It is a figure which shows the amplitude of the high frequency component of d-axis current with respect to each phase angle when a standardized primary resistance value is changed with respect to a certain synchronous motor.

Explanation of symbols

1: Speed setter 2: Pulse generator (PG)
3: Position / speed detector 4: Speed controller 5: q-axis current command device 6: d-axis current command device 7: current detector 8: phase angle calculator 9: vector rotator 10: d-axis current controller 11 : Q-axis current regulator 12: vector rotator 13: inverter control circuit 14: controller 15: storage device 16: high frequency oscillator 17: high frequency component detector 18: phase angle calculator / switcher 19: adder 20, 21: Changeover switch 100: Three-phase AC power supply 200: Diode rectifier 300: Smoothing capacitor 400: Inverter unit 500: Synchronous motor

Claims (1)

A synchronous motor driving device that drives a synchronous motor including an incremental type pulse generator at a variable speed by an inverter unit,
Speed setting means for giving a speed command value of the synchronous motor;
Position / speed detection means for detecting the position and speed of the rotor based on the output pulse of the pulse generator;
Speed adjusting means for generating a torque command value so that there is no deviation between the speed detection value output from the position / speed detection means and the speed command value;
Q-axis current command means for generating a q-axis current command value in a direction orthogonal to the magnetic pole position from the torque command value;
D-axis current command means for generating a d-axis current command value in the same direction as the magnetic pole position;
A phase angle calculation means for calculating a phase angle based on a position detection value output from the position / velocity detection means;
Current detection means for detecting the motor current;
First vector rotation means for decomposing the motor current into a d-axis current and a q-axis current using the phase angle;
d-axis current adjusting means for generating a d-axis voltage command value and a q-axis voltage command value so as to eliminate a deviation between the d-axis current and the d-axis current command value and a deviation between the q-axis current and the q-axis current command value, and q-axis current adjusting means;
Second vector rotation means for converting a d-axis voltage command value and a q-axis voltage command value into a three-phase AC voltage command using the phase angle;
Control means for generating a driving pulse for the switching element of the inverter unit according to a three-phase voltage command;
In a synchronous motor drive device comprising:
Means for outputting a voltage command value corresponding to a normalized primary resistance value as a constant of the synchronous motor;
Means for generating a magnetic pole position estimation d-axis voltage command value by superimposing a high-frequency signal on the voltage command value;
High-frequency component detection means for detecting a high-frequency component of the d-axis current detection value output from the first vector rotation means;
Based on the amplitude of the high-frequency component detected by the high-frequency component detection means, when the magnetic pole position is estimated, the second magnetic pole position estimation d-axis voltage command value is replaced with the d-axis voltage command value from the d-axis current adjustment means. The phase angle for determining the electrical angle for outputting the magnetic pole position estimation d-axis voltage command value is calculated, and this phase angle is converted into the phase angle from the phase angle calculation unit. Instead, a phase angle calculation / switching means to be given to the second vector rotating means,
With
A synchronous motor driving device characterized in that a true magnetic pole position is estimated from a phase angle at which an amplitude of a high frequency component detected by the high frequency component detecting means is maximized.

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