JP2015220944A - Sensorless drive device of synchronous motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensorless drive device of a synchronous motor which allows for shockless switching of a control method of an inverter.SOLUTION: A sensorless drive device of a synchronous motor includes: change-over switches 106, 115, 114a for switching from V/f constant control to sensorless vector control when a speed estimation value of a synchronous motor SM exceeds a speed reference value; a d-axis current regulator 111 generating a d-axis voltage command value from a d-axis current command value common to both control times; a q-axis current regulator 107 generating a q-axis voltage command value from a q-axis current command value of zero during V/f constant control, and generating a q-axis voltage command value from the speed deviation during sensorless vector control; acceleration deceleration calculation means outputting an acceleration deceleration calculation value generated from the speed command value during V/f constant control; and a speed estimator 114 generating a gradually changing speed estimation value by using the acceleration deceleration calculation value used during V/f constant control as an initial value, during sensorless vector control.

Description

  The present invention relates to a sensorless drive device for a synchronous motor in which a control method is changed according to a rotation speed.

Conventionally, a technique for estimating the rotational speed of a synchronous motor without a magnetic pole position sensor or a speed sensor based on an induced voltage is known. However, according to this method, since the induced voltage is small when the synchronous motor rotates at low speed, it is difficult to accurately estimate the rotation speed and drive the synchronous motor.
For this reason, for example, in Patent Document 1, V / f constant control that does not require speed / magnetic pole position information is performed during low-speed operation of the synchronous motor, and so-called sensorless vector control is performed during high-speed operation. Realizes sensorless control over a wide range.

JP 2004-48886 A (paragraphs [0022] to [0027], FIG. 1 and the like)

However, in the control method described in Patent Document 1, when the control is switched from V / f constant control at low speed operation to sensorless vector control at high speed operation, the d-axis current command value and the q-axis current command value are set to 0 by the changeover switch. And switching between the predetermined value.
For this reason, when the control is switched, the motor current suddenly changes and a shock occurs in the torque, which may adversely affect the load.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a sensorless drive device for a synchronous motor that can switch a control method without shock.

In order to solve the above-mentioned problem, the invention according to claim 1 is directed to a sensorless vector control means for controlling a synchronous motor driving inverter by estimating a magnetic pole position of a synchronous motor without using a magnetic pole position sensor; A synchronous motor sensorless drive device having a constant V / f control means that controls the inverter by the V / f constant control means during low-speed operation of the synchronous motor and during medium-high speed operation. In the sensorless driving apparatus that controls the inverter by the sensorless vector control means,
A speed comparison means for comparing the estimated speed value of the synchronous motor with a reference speed value;
Switching means for switching the control means of the inverter from the V / f constant control means to the sensorless vector control means when the speed comparison means detects that the speed estimated value exceeds the speed reference value;
D-axis current adjusting means for generating a d-axis voltage command value based on a d-axis current command value continuously generated during V / f constant control and sensorless vector control;
At the time of constant V / f control, a q-axis voltage command value is generated based on the q-axis current command value set to zero, and at the time of sensorless vector control, based on the deviation between the speed command value and the estimated speed value. q-axis current adjusting means for generating a q-axis voltage command value;
Acceleration / deceleration calculation means for outputting an acceleration / deceleration calculation value generated from the speed command value as the estimated speed value during V / f constant control;
And a speed estimation unit that generates a speed estimation value that gradually changes using the acceleration / deceleration calculation value used in the V / f constant control as an initial value during sensorless vector control.

  According to a second aspect of the present invention, in the sensorless drive device for the synchronous motor according to the first aspect, the speed estimation unit includes a proportional-integral control unit, and the proportional gain of the proportional-integral control unit passes through a first-order lag filter. It is characterized by gradually changing from 0 to a predetermined value.

  The invention according to claim 3 is the sensorless drive device for a synchronous motor according to claim 1 or 2, wherein an effective value calculation means for calculating a terminal voltage effective value from a terminal voltage detection value of the synchronous motor, and the terminal voltage effective Motor voltage adjusting means that operates so that a value does not exceed the terminal voltage command value, and adding means for adding the output of the motor voltage adjusting means to a d-axis current setting value to generate the d-axis current command value; It is equipped with.

  ADVANTAGE OF THE INVENTION According to this invention, the shock at the time of switching the control method of a synchronous motor can be eliminated, and a synchronous motor can be driven stably over a wide range from a low speed area to a medium-high speed area.

It is a block diagram which shows the structure of the sensorless drive device which concerns on embodiment of this invention. It is a vector figure (Drawing 2 (a)) of d axis current and q axis voltage of a synchronous motor, and is a vector figure (Drawing 2 (b)) of magnetic flux φ and q axis voltage. It is a block diagram of the speed estimator in FIG. It is a vector diagram which shows each element of the controller input in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of this embodiment.
First, in the main circuit, an inverter 3 is connected via a DC intermediate capacitor 2 to the DC side of the converter 1 connected to the three-phase AC power system, and a synchronous motor SM is connected to the AC output side. .

The configuration of the control device that controls the inverter 3 is as follows.
That is, a current sensor 101 and a voltage sensor 102 are connected to the AC output side of the inverter 3, and current detection values and voltage detection values from the sensors 101 and 102 are input to the coordinate converter 103. The coordinate converter 103 converts the input signal using the angle command value θ, converts the q-axis current detection value I _q , the d-axis current detection value I _d , the q-axis voltage detection value V _q , and the d-axis voltage detection value V. _d is output.
Further, the voltage value detected by the voltage sensor 102 is input to an effective value computing unit 104, the terminal voltage effective value V ₁ of the synchronous motor SM by the effective value computing unit 104 is calculated.

Further, the deviation between the speed command value n ^* of the synchronous motor SM and the estimated speed value n is input to the speed regulator 105, and the output is input to one end of the first changeover switch 106, and the changeover switch 106. The q-axis current set value I _q1 ^* (= 0) is input to the other end.
The first changeover switch 106 is connected to the q-axis current set value I _q1 ^* side when V / f constant control is selected by the output signal S of the speed comparator 116 described later (when S = 0). When sensorless vector control is selected (when S = 1), it is connected to the speed regulator 105 side, and the output of the changeover switch 106 becomes the q-axis current command value I _q ^* .
The deviation between the q-axis current command value I _q ^* and the q-axis current detection value I _q is input to the q-axis current regulator 107 composed of a proportional-plus-integral regulator, and the q-axis voltage is changed by the operation to make the deviation zero. A command value V _q ^* is generated.

The deviation between the terminal voltage command value V ₁ ^{* of the} synchronous motor SM and the terminal voltage effective value V ₁ is input to the motor voltage regulator 109, and the motor voltage regulator 109 operates so that the deviation becomes zero. . The output of the motor voltage regulator 109 is limited to a negative value by the limiter 110 and then added to a preset d-axis current set value I _d1 ^* to have a positive value as will be described later. A command value I _d ^* is generated. The terminal voltage effective value V ₁ is controlled by the operation of the motor voltage regulator 109 so as not to exceed the terminal voltage command value V ₁ ^* .
Further, the deviation between the d-axis current command value I _d ^* and the detected d-axis current value I _d is input to the d-axis current regulator 111 composed of a proportional-plus-integral regulator, and the deviation is made zero by the operation. A d-axis voltage command value V _d ^* is generated.

The q-axis voltage command value V _q ^* and the d-axis voltage command value V _d ^* are input to the coordinate converter 108, and three-phase voltage command values V _u ^* , V _v ^* , V are obtained by coordinate conversion using the angle command value θ. V _w ^* is calculated. These voltage command values V _u ^* , V _v ^* , and V _w ^* are input to the PWM generator 112, and a PWM signal (drive signal) for on / off control of the semiconductor switching element of the inverter 3 is obtained by comparison with the carrier. Generated.

On the other hand, the speed command value n ^* is input to the acceleration / deceleration calculator 113 and output as an acceleration / deceleration calculation value n _hlr ^* . The acceleration / deceleration calculation value n _hlr ^* is input to the second changeover switch 115 together with the estimated speed value n ′ output from the speed estimator 114. The change-over switch 115 is connected to the acceleration / deceleration calculation value n _hlr ^* side when V / f constant control is selected by the output signal S of the speed comparator 116 (when S = 0), and sensorless vector control is performed. When it is selected (when S = 1), it is connected to the speed estimated value ω side, and the output of the changeover switch 115 becomes the final speed estimated value n.

The speed estimated value n is compared with the speed reference value n _ref by the speed comparator 116, and the output signal S of the speed comparator 116 is S = 0 when n ≦ n _ref and S = 1 when n> n _ref. It becomes. Further, an angle command value θ is calculated by integrating the estimated speed value n by the integrator 117, and this angle command value θ is input to the coordinate converters 103 and 108.

Here, FIG. 3 is a block diagram showing a configuration of the speed estimator 114.
In FIG. 3, 114 a is a third changeover switch, and this changeover switch 114 a is “0” when V / f constant control is selected by the output signal S of the speed comparator 116 (when S = 0). When the sensorless vector control is selected (when S = 1), it operates so as to be connected to the “K _p ” side. Here, _Kp is a proportional gain.
The output of the selector switch 114a (proportional gain) is input through the first-order lag filter 114b to a proportional integral controller 114c, the proportional integral controller 114c, and the integral gain K _i, acceleration and deceleration of the initial value of the velocity estimate The calculated value n _hlr ^{* is} also input.

Furthermore, Formula 2 obtained by modifying the voltage model formula (Formula 1) of the synchronous motor SM is input to the proportional integration controller 114c.
[Formula 1]
V _d = R × I _d −ω × L _q × I _q
[Formula 2]
R × I _d −ω × L _q × I _q −V _d
In Equations 1 and 2, R is the armature winding resistance of the synchronous motor SM, ω is the angular velocity, L _q is the q-axis inductance, and the vector diagram of each element in Equation 1 is as shown in FIG.

Speed estimator 114 configured as described above, when the sensor-less vector control (when S = 1), the proportional integral controller 114c is a proportional gain gradually changes from 0 to K _p and integral gain K _i V / f constant control (when S = 0) by performing proportional integral calculation so that the controller input (R × I _d −ω × L _q × I _q −V _d ) is set to 0 using The estimated speed value ω with n _hlr ^* used as the initial value is calculated.

Next, the operation of this embodiment will be described.
First, at the time of low speed operation of the synchronous motor SM, V / f constant control is performed as in the prior art. During the low speed operation of the synchronous motor SM, n ≦ n _ref holds, and the output signal S of the speed comparator 116 is zero. Therefore, since the first and second changeover switches 106 and 115 are on the S = 0 side as shown in FIG. 1, I _q1 ^* = 0 is selected as the q-axis current command value I _q ^* , and the estimated speed value The acceleration / deceleration calculation value n _hlr ^* is selected as n.

In this case, q-axis current regulator _{^{107, I q * (= I q1}} * = 0) and generates a q-axis voltage command value _V ^{q *} the deviation between _{I q} as inputs.
Further, a d-axis current command value I _d ^* is generated by adding the output from the motor voltage regulator 109 via the limiter 110 and the d-axis current set value I _d1 ^* , but the d-axis current set value I _d1 is generated. ^* Is preset so that the d-axis current I _d (d-axis current command value I _d ^* ) becomes a positive value as shown in FIG. Thereby, the voltage (X × I _d ) generated when the d-axis current I _d flows through the impedance (inductive reactance X) of the synchronous motor SM is on the q-axis of the vector diagram as shown in FIG. Occurs with positive polarity.

On the other hand, the induced voltage emf generated during the rotation of the synchronous motor SM also becomes a positive voltage V _q on the q axis orthogonal to the magnetic flux φ as shown in FIG. 2B, and the voltage (X) in FIG. × I _d ) and the vector orientation match. That is, since the phase of the output voltage of the inverter 3 and the induced voltage of the synchronous motor SM substantially coincide with each other, an error in the magnetic pole position (speed) when switching from V / f constant control to sensorless vector control is reduced. Can be switched without shock.

Next, the operation when switching from V / f constant control to sensorless vector control will be described.
When the first and second changeover switches 106 and 115 are in the state shown in FIG. 1 and the speed estimated value n (acceleration / deceleration calculation value n _hlr ^* ) becomes larger than the speed reference value n _ref , the output of the speed comparator 116 is output. Signal S = 1. As a result, the first and second changeover switches 106 and 115 and the third changeover switch 114a in the speed estimator 114 are all switched to the S = 1 side.

As described above, the speed estimator 114 that was not operating during the V / f constant control gradually changes from 0 with the acceleration / deceleration calculation value n _hlr ^* used during the V / f constant control as the initial value. a proportional integral control using a proportional gain K _p and integral gain K _i, the speed estimate ω is computed. In this operation, since the magnetic pole position error inherent in the constant V / f control is not the sensorless vector control and involves the movement of the rotating shaft, the proportional gain of the proportional integral controller 114c is gradually changed from 0. This is to make the movement of the rotating shaft gentle and to make the torque shockless when switching the control method.

The speed estimation value ω (speed estimation value n) obtained in this way is input to the integrator 117 to calculate the angle command value θ, and at the same time, a speed adjustment is input in which a deviation between the speed command value n ^* and the speed estimation value n is input. The q-axis current command value I _q ^* is calculated by the operation of the device 105.
On the other hand, the d-axis current command value I _d ^* is generated in the same manner as in the V / f constant control, and the final voltage is determined based on the q-axis current command value I _q ^* and the d-axis current command value I _d ^*. The command values V _u ^* , V _v ^* , and V _w ^* are respectively calculated.

  The sensorless drive device according to the present invention can be used when a synchronous motor used for various industrial applications such as an air conditioner and a transport machine is driven in a wide speed range.

1: Converter 2: DC intermediate capacitor 3: Inverter 101: Current sensor 102: Voltage sensor 103, 108: Coordinate converter 104: Effective value calculator 105: Speed controller 106: First changeover switch 107: q-axis current adjustment Unit 109: Motor voltage regulator 110: Limiter 111: d-axis current regulator 112: PWM generator 113: Acceleration / deceleration calculator 114: Speed estimator 114a: Third changeover switch 114b: Primary delay filter 114c: Proportional integration Controller 115: second changeover switch 116: speed comparator 117: integrator SM: synchronous motor

Claims (3)

Sensorless vector control means for controlling the inverter for driving the synchronous motor by estimating the magnetic pole position of the synchronous motor without using the magnetic pole position sensor, and V / f constant control means for controlling the inverter at V / f constant. A sensorless drive device for a synchronous motor, wherein the inverter is controlled by the V / f constant control means during low speed operation of the synchronous motor and the inverter is controlled by the sensorless vector control means during medium / high speed operation. ,
A speed comparison means for comparing the estimated speed value of the synchronous motor with a reference speed value;
Switching means for switching the control means of the inverter from the V / f constant control means to the sensorless vector control means when the speed comparison means detects that the speed estimated value exceeds the speed reference value;
D-axis current adjusting means for generating a d-axis voltage command value based on a d-axis current command value continuously generated during V / f constant control and sensorless vector control;
A q-axis voltage command value is generated based on a q-axis current command value set to zero during V / f constant control, and a q-axis based on a deviation between the speed command value and the estimated speed value during sensorless vector control. Q-axis current adjusting means for generating a voltage command value;
Acceleration / deceleration calculation means for outputting an acceleration / deceleration calculation value generated from the speed command value as the estimated speed value during V / f constant control;
Speed estimation means for generating a speed estimation value that gradually changes with the acceleration / deceleration calculation value used in the V / f constant control as an initial value during sensorless vector control;
A sensorless drive device for a synchronous motor, comprising: In the sensorless drive device of the synchronous motor according to claim 1,
The speed estimation means includes proportional-integral control means,
2. A sensorless drive device for a synchronous motor, wherein a proportional gain of the proportional integral control means gradually changes from 0 to a predetermined value through a first-order lag filter. In the sensorless drive device for a synchronous motor according to claim 1 or 2,
Effective value calculating means for calculating the terminal voltage effective value from the terminal voltage detection value of the synchronous motor;
Motor voltage adjusting means that operates so that the terminal voltage effective value does not exceed the terminal voltage command value;
Adding means for adding the output of the motor voltage adjusting means to a d-axis current set value to generate the d-axis current command value;
A sensorless drive device for a synchronous motor, comprising:

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