JP4867067B2 - Control device for permanent magnet type synchronous motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for a permanent magnet type synchronous motor (PM motor) having saliency on a rotor, and in particular, does not use a position detection sensor for detecting a magnetic pole position of a rotor (hereinafter referred to as a rotor position). The present invention relates to a control device for a permanent magnet type synchronous motor.
[0002]
[Prior art]
Rotor position information is required for high performance control of a permanent magnet synchronous motor.
In general, an encoder, a resolver, or the like is used as a position detection sensor. For the purpose of reducing the cost, sensorless control that electrically estimates and calculates the rotor position from information on the voltage and current of the motor has been proposed. As one of the techniques, a magnetic pole position detection device described in Japanese Patent Laid-Open No. 7-245981 is known. This known method for detecting the rotor position applies a high-frequency voltage to a permanent magnet synchronous motor having saliency, and estimates and calculates the rotor position from the high-frequency current resulting from the saliency flowing as a result. Is.
[0003]
However, the rotor position estimation calculation method disclosed in Japanese Patent Laid-Open No. 7-245981 may in principle have a position estimation error of 180 °, and a calculation for correcting this (hereinafter, this calculation is referred to as “magnetic pole discrimination”). ") Is required. As this magnetic pole discrimination method,
・ Journal of the Institute of Electrical Engineers of Japan D “Industrial Application Category” November 1990 Vol.110 pp.1193-1200
・ The Institute of Electrical Engineers of Japan D “Industrial Application Category” July 1996 Vol.116 pp736 ～ 742
・ IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL.32, NO.5, SEPTEMBER / OCTOBER 1996
Etc. have been proposed.
[0004]
Each of the magnetic pole discrimination methods uses the magnetic saturation characteristics of the motor core, and the difference in current change rate when the direct current is controlled to be positive or negative using the rotor position estimation value. Use to determine the magnetic pole. Here, in order to facilitate understanding in the future, terms will be described.
First, the direct axis is a coordinate axis taken in the magnetic pole direction of the rotor permanent magnet, and the direct axis current is a current component in the direct axis direction. In other words, the positive direct current acts to increase the magnetic flux by the permanent magnet, and the negative direct current is a current component that acts to weaken the magnetic flux by the permanent magnet. The voltage is defined in the same way, and the direct axis voltage is a voltage component in the direction of the direct axis. Also, the horizontal axis is defined in the direction orthogonal to the straight axis, and the current and voltage in the horizontal axis direction are referred to as the horizontal axis current and the horizontal axis voltage, respectively.
[0005]
FIG. 4 shows the prior art of the magnetic pole discrimination method of the sensorless control device of the permanent magnet type synchronous motor.
In FIG. 4, the voltage command of the electric motor (PM motor) 40 is input to the coordinate converter 1. Here, the square-axis voltage command v _d ^* is usually superimposed with a square-wave high-frequency voltage (a high-frequency voltage having a frequency different from that of the fundamental voltage component, and this voltage is hereinafter referred to as a square-wave voltage). Zero is given as the voltage command v _q ^* .
[0006]
The coordinate converter 1 calculates a three-phase voltage command v _u ^* , v _v ^* , v _w ^* based on the estimated position value θ output from the integrator 8 and the voltage command v _d ^* , v _q ^*. . These voltage commands v _u ^* , v _v ^* , v _w ^* are converted by the PWM circuit 3 into gate signals for the switching elements of the power converter (inverter) 30 to control the terminal voltage of the electric motor 40. Reference numeral 20 denotes a three-phase AC power source.
[0007]
The coordinate converter 2 calculates a direct current i _d and a horizontal current i _q from the armature currents i _u and i _w detected from the output side of the power converter 30 and the estimated position value θ. The high frequency separation filter 4 separates and extracts the horizontal axis high frequency current i _qh having the same frequency component as the square wave voltage from i _q .
[0008]
Note that two switches A and three switches B are provided as interlocking switches, and the voltage selected by the switch A or the switch B is superimposed on the direct-axis voltage command v _d ^* . Further, in the memory 5 is input by the direct-axis current i _d is the switch B, the integrator 8, the output switch A velocity estimator 7 which horizontal axis high frequency current i _qh is input, zero by the switch B It is designed to be entered.
[0009]
At the start of operation, first, position estimation using saliency is performed. As shown, all the switches A are closed and all the switches B are open. Since the switch A is closed, the direct-axis voltage command v _d ^* is a square wave voltage whose value repeats positively and negatively as shown.
The speed estimator 7 calculates a speed estimated value from the value of the horizontal axis high frequency current i _qh separated by the high frequency separation filter 4, and the integrator 8 integrates the speed estimated value to calculate a position estimated value θ.
As a result, the position estimated value θ converges to a true value or a value having an error of 180 °.
[0010]
Next, magnetic pole discrimination will be described. In this case, contrary to the state shown in the figure, all the switches A are open and all the switches B are closed. As the direct-axis voltage command v _d ^* , instead of the square wave voltage, a pulse voltage having positive and negative polarity is intermittently given as a magnetic pole discrimination test signal, and the direct-axis current _id is changed from zero to positive. Or from zero to negative.
At this time, since the superposition of the square wave voltage is stopped and the speed / position estimation calculation using the horizontal axis high-frequency current i _qh cannot be performed, the operation is stopped by inputting zero to the integrator 8 to estimate the position. The value θ is fixed.
Direct axis current i _d of the change rate when the positive and negative pulse voltage is applied △ i _dp, △ i _dm are stored in the memory 5, respectively.
[0011]
The magnetic pole discriminator 6 compares the values of _{Δi dp} and Δi _dm , presets the output of the integrator 8 by the following formula 1, and corrects the calculation error of the position estimation value. That is, if the value obtained by integrating the output of the speed estimator 7 is set as the first position estimated value, the second position estimated value θ corrected by presetting the first position estimated value by the equation 1 is generated. Output.
[0012]
[Formula 1]
(a) When Δi _dp <Δi _dm → θ = θ (previous value) + 180 °
(b) When Δi _dp > Δi _dm → θ = θ (previous value)
[0013]
[Problems to be solved by the invention]
In the conventional control, it is necessary to stop the position estimation calculation when determining the magnetic pole. For this reason, when the rotor is rotating, the position of the rotor is unknown, and there is a possibility that the pulse voltage cannot be accurately output in the positive and negative directions of the straight axis and the magnetic pole determination is erroneous. Further, since the fundamental wave current cannot be controlled during the magnetic pole discrimination, an excessive current may flow through the armature due to the induced voltage accompanying the rotation of the rotor.
In view of this, the present invention provides a control apparatus for a permanent magnet type synchronous motor that enables position estimation calculation to be performed simultaneously with magnetic pole discrimination, and further prevents the occurrence of overcurrent by enabling control of the fundamental current even at the time of magnetic pole discrimination. Is to provide.
[0014]
[Means for Solving the Problems]
In the present invention, a high-frequency voltage having a different frequency, for example, a square-wave voltage is superimposed on the fundamental wave voltage, and the position estimation value is calculated using the high-frequency current flowing through the armature. Then, the magnetic pole discrimination test signal is synchronized with the high frequency voltage while superimposing the pulse voltage as the magnetic pole discrimination test signal on the high frequency voltage or controlling the polarity of the direct axis current or the horizontal axis current and estimating the position. A component is extracted from the detected current, and magnetic pole discrimination is performed based on the rate of change and amplitude of the current at this time to correct the position estimation value. The pulse width of the pulse voltage is long enough to reach the magnetic saturation region and is synchronized with the high frequency voltage.
The signal for position estimation can be directly detected by extracting the frequency component of the superimposed high-frequency voltage from the detection current using a filter. The test signal for magnetic pole discrimination is detected easily and directly at the same time as detecting the signal for position estimation by superimposing a pulse voltage synchronized with the high-frequency voltage with a certain phase difference. be able to.
[0015]
That is, the invention described in claim 1 is a control device for driving a permanent magnet type synchronous motor having saliency in a rotor by a power converter, and the rotor is obtained from the estimated speed value without using a position detection sensor. In the control device for a permanent magnet type synchronous motor that estimates the position and uses the position estimated value to control the voltage command for the motor separately into the direct-axis voltage command and the horizontal-axis voltage command,
Means for generating a direct-axis voltage command by superimposing a high-frequency voltage on the direct-axis fundamental wave voltage command;
Means for decomposing the armature current of the motor into a direct axis current and a horizontal axis current, and extracting a high frequency current having the same frequency as the high frequency voltage from the horizontal axis current;
Means for controlling the average value of the direct-axis current to zero and generating the direct-axis fundamental wave voltage command;
Means for controlling the average value of the horizontal axis current to zero to generate a horizontal axis voltage command;
Means for calculating a rotor speed estimate from the high-frequency current and integrating the speed estimate to calculate a first position estimate;
While calculating the speed estimated value and the first position estimated value, the function of controlling the average value of the direct-axis current to zero is stopped and a pulse voltage having a positive polarity and a negative polarity is superimposed on the high-frequency voltage. In addition, the first position estimated value is corrected and the second position estimated value is calculated based on the rate of change of the direct current when the positive pulse voltage is superimposed and when the negative pulse voltage is superimposed. Means for performing.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the control block diagram of FIG. 1 shows a first embodiment of the present invention.
The same constituent elements as those in FIG. 4 are denoted by the same reference numerals, and different points will be mainly described below. In this embodiment, the addition result of the square wave voltage and the pulse voltage is expressed as a direct-axis voltage command v _d ^*. Is added, and all the switches A and the switch B provided on the input side of the integrator 8 in FIG. 4 are removed.
The switch B in this embodiment can input a pulse voltage to one input terminal of the adder 9, and can input a direct current i _d to the memory 5 at the same time.
[0017]
Next, the operation of this embodiment will be described.
First, the switch B is opened, and a square wave voltage is input to the coordinate converter 1 as a direct-axis voltage command v _d ^* to perform an estimation calculation of the rotor position. At this time, as in the prior art, the speed estimator 7 calculates a speed estimated value from the horizontal-axis high-frequency current i _qh (having a frequency component of a square wave voltage) extracted and separated from the high-frequency separation filter 4, and an integrator 8 integrates the speed estimation value to calculate the first position estimation value θ.
[0018]
Thereafter, the switch B is closed, the square wave voltage and the pulse voltage are added by the adder 9 to generate a direct-axis voltage command v _d ^* , and this command v _d ^* is input to the coordinate converter 1. Here, the pulse width of the pulse voltage is set to a period that is an integral multiple of the square wave voltage in consideration of reaching the magnetic saturation region, and is synchronized with the square wave voltage.
[0019]
Further, while performing the position estimate, the magnetic pole discrimination test signal component at a timing synchronized with the square wave voltage is extracted from the direct axis current i _d, the rate of change of direct axis current i _d △ i _dp, the memory 5 △ i _dm The magnetic pole is discriminated in accordance with Equation 1 described above. In the magnetic pole discriminator 6, for example, when Formula 1 (a) is established, a signal for adding 180 degrees to the first position estimated value is preset in the integrator 8, thereby calculating the first position estimated value. The error is corrected, and the second position estimated value θ is generated and output.
[0020]
With the above configuration, the magnetic pole discrimination can be performed simultaneously and accurately while superimposing the pulse voltage on the square wave voltage and estimating the rotor position.
[0021]
The control block diagram of FIG. 2 shows a second embodiment of the present invention.
In this embodiment, a direct-axis current regulator 11 as means for outputting a direct-axis fundamental wave voltage command v _d ^** by further controlling the average value of the direct-axis current to zero with respect to the configuration of FIG. A horizontal axis current regulator 12 as a means for outputting the horizontal axis voltage command v _q ^* by controlling the average value of the horizontal axis current to zero and an adder 10 are added to perform position estimation and magnetic pole discrimination. However, the fundamental wave current is also controlled.
[0022]
The direct-axis current regulator 11 receives the direct-axis fundamental wave current i _db and the direct-axis current command value i _d ^* (= 0) output from the high-frequency separation filter 4, and the output is the direct-axis fundamental wave voltage. The command v _d ^** is added to one input terminal of the adder 10. The output of the adder 9 is added to the other input terminal of the adder 10, and the output of the adder 10 is input to the coordinate converter 1 as the final straight axis voltage command v _d ^* . Further, the horizontal axis current regulator 12 receives the horizontal axis fundamental wave current i _qb and the horizontal axis current command value i _q ^* (= 0) output from the high frequency separation filter 4, and the output is the horizontal axis voltage. The command v _q ^* is input to the coordinate converter 1.
[0023]
The operation of this embodiment will be described. At the time of estimating the rotor position, the switch B is opened and only the square wave voltage is applied to the adder 9.
The high-frequency separation filter 4 includes a straight-axis fundamental wave current i _db and a horizontal-axis fundamental wave current i _{qb obtained} by removing the frequency component of the square-wave voltage from i _d and i _q , and a horizontal-axis high-frequency current having the same frequency component as the square-wave voltage. i _qh is separated and extracted.
The direct-axis current regulator 11 amplifies the deviation between i _d ^* (= 0) and i _db to calculate a straight-axis fundamental wave voltage command v _d ^** , and the adder 10 ^generates a square wave to v _d ^**. The voltage is superimposed to obtain the final straight axis voltage command v _d ^* . Further, the horizontal axis current regulator 12 calculates the horizontal axis voltage command v _q ^* by amplifying the deviation between i _q ^* (= 0) and i _qb . By the operation of these regulators 11 and 12, the average value of the direct axis current and the average value of the horizontal axis current are controlled to zero.
[0024]
The speed estimator 7 calculates a speed estimated value from the horizontal axis high-frequency current i _qh output from the high-frequency separation filter 4, and the integrator 8 integrates the speed estimated value to calculate a first position estimated value θ.
[0025]
When the magnetic pole is discriminated, the switch B is closed, and the operations of the adders 9 and 10 cause the square wave voltage and the positive polarity as the magnetic pole discrimination test signal to the straight axis fundamental wave voltage command v _d ^** . And the direct-axis voltage command v _d ^* is generated by superimposing the negative pulse voltage.
The time for applying the pulse voltage is made sufficiently short so that the direct current regulator 11 cannot follow. When the pulse voltage is applied to the positive polarity and to the negative polarity, the change rates Δ i _dp and Δ i _dm of i _d are stored in the memory 5, respectively, and the magnetic pole discriminator 6 is preset according to the equation 1. Then, the first position estimated value is corrected by the same method as in the first embodiment, and the second position estimated value θ is generated.
[0026]
With the above configuration, the magnetic pole can be accurately discriminated even when the electric motor 40 is rotating, and the electric motor can be protected by preventing an overcurrent due to the induced voltage.
[0027]
Next, the control block diagram of FIG. 3 shows a third embodiment of the present invention.
This embodiment is characterized in that a switch C is added between the direct current regulator 11 and the adder 10 in the embodiment of FIG. The operation of the switch C is “open” if the switch B is closed and the pulse voltage as the magnetic pole discrimination test signal is a positive or negative value, and “closed” otherwise.
[0028]
The operation of this embodiment will be described below. The estimation operation of the rotor position is the same as in the first and second embodiments.
When discriminating the magnetic pole, the switch C is opened when the pulse voltage is positive or negative with the switch B closed, so that the control of the direct current is not performed, and a large direct axis is generated by the positive or negative pulse voltage. Current flows. Thereby, it is possible to sufficiently can flow straight axis current i _d as magnetic saturation, the magnetic pole determination with high accuracy through the memory 5 and the pole discriminator 6. In order to supply a large direct-axis current i _d in the present embodiment, to increase to the extent that the pulse voltage is a period of the motor and the inverter is positive or negative is allowed desirable.
[0029]
【Effect of the invention】
As described above, according to the present invention, the position estimation calculation can be executed simultaneously with the magnetic pole discrimination, and the fundamental current can be controlled even during the magnetic pole discrimination, thereby preventing the occurrence of overcurrent. In addition, even when the rotor is rotating, the calculation of the rotor position can be performed accurately, so that there is an effect that a quick start is possible.
[Brief description of the drawings]
FIG. 1 is a control block diagram showing a first embodiment of the present invention.
FIG. 2 is a control block diagram showing a second embodiment of the present invention.
FIG. 3 is a control block diagram showing a third embodiment of the present invention.
FIG. 4 is a control block diagram showing a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 2 Coordinate converter 3 PWM circuit 4 High frequency separation filter 5 Memory 6 Magnetic pole discriminator 7 Speed estimator 8 Integrator 9, 10 Adder 11 Straight axis current regulator 12 Horizontal axis current regulator 13 Acceleration detector 20 Three phase AC power supply 30 Power converter 40 Permanent magnet synchronous motor (PM motor)
A, B, C switch

Claims (1)

A control device for driving a permanent magnet synchronous motor having saliency on a rotor by a power converter, estimating a rotor position from a speed estimated value without using a position detection sensor, and calculating the position estimated value In a control device for a permanent magnet type synchronous motor that uses a voltage command for a motor to be controlled separately to a direct-axis voltage command and a horizontal-axis voltage command,
Means for generating a direct-axis voltage command by superimposing a high-frequency voltage on the direct-axis fundamental wave voltage command;
Means for decomposing the armature current of the motor into a direct axis current and a horizontal axis current, and extracting a high frequency current having the same frequency as the high frequency voltage from the horizontal axis current;
Means for controlling the average value of the direct-axis current to zero and generating the direct-axis fundamental wave voltage command;
Means for controlling the average value of the horizontal axis current to zero to generate a horizontal axis voltage command;
Means for calculating a rotor speed estimate from the high-frequency current and integrating the speed estimate to calculate a first position estimate;
While calculating the speed estimated value and the first position estimated value, the function of controlling the average value of the direct-axis current to zero is stopped and a pulse voltage having a positive polarity and a negative polarity is superimposed on the high-frequency voltage. In addition, the first position estimated value is corrected and the second position estimated value is calculated based on the rate of change of the direct current when the positive pulse voltage is superimposed and when the negative pulse voltage is superimposed. Means to
A control device for a permanent magnet type synchronous motor.

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