JPH11262286A - Controller of permanent magnet synchronous motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controller of a permanent magnet synchronous motor, whereby the position of its magnetic pole is estimated to enable it to start without reverse rotation, even though no positional sensor of its magnetic pole is mounted on it. SOLUTION: In the stationary state of a permanent magnet synchronous motor, the response times of the step-responses of its currents are measured at a plurality of electric angles. Since its inductance value becomes small by the effects of the saturation of its magnetic flux near its magnetic pole to make short its response time and conversely, its inductance value becomes large in a direction opposite to the position of its magnetic pole to make long its response time, searching for the electric angle in the opposite direction to the position of its magnetic pole, whereat its response time becomes the longest, 180 deg. is added/subtracted to/from the obtained electric angle for estimating the resultant electric angle value as the positional value of its magnetic pole.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a control device for a permanent magnet synchronous motor.

[0002]

2. Description of the Related Art Permanent synchronous motors (Permanen)
t Magnet Synchronous Moto
r, hereinafter referred to as PMSM) is being used widely because it is more efficient than induction motors and can be made smaller for the same output.

[0003] PMSM position control or speed control generally requires a PG (pulse generator) and a magnetic pole position sensor, which are expensive.
Also, sensorless control is desired from the viewpoint of installation environment, life, and noise resistance.

When the PMSM is stationary and there is no magnetic pole position sensor, the magnetic pole position is not known at all. Therefore, when the inverter is started from an appropriate electrical angle, the motor may temporarily reverse or rattle. is there. This makes it impossible to apply PMSM in some applications.

[0005] An induced voltage can be used for estimating the speed during rotation, and several estimation methods have been proposed. However, since there is no induced voltage at the time of starting, development of a position estimating method at the time of starting is desired. I have.

[0006]

Therefore, in the present invention,
Focusing on the following points, an object of the present invention is to provide a control device for a permanent magnet synchronous motor that can estimate a magnetic pole position without a magnetic pole position sensor and start without causing reverse rotation.

FIG. 19 shows a current vector flowing through the armature and a positional relationship between the motor magnetic poles. When the magnitude of the current vector is constant in FIG. 19, the total magnetic flux linked to the equivalent conversion winding changes depending on the relative angle θ1 between the magnetic pole axis and the current vector. When the interlinkage magnetic flux is large, the inductance is small because the influence of the magnetic flux saturation of the iron core is large, and when the interlinkage magnetic flux is small, the inductance is large because the influence of the magnetic flux saturation is small.

FIG. 20 shows an example of a block diagram of a current control system of the PMSM. 101 is an inverter, 102 is a PMS
M, 103A and 103B are current sensors for detecting the inverter output current, 104 is an electric angle generator for determining the electric angle (phase) θe of the inverter output voltage, and 105 is the stationary coordinate system current signal iu from the current sensors 103A and 103B.
convert iw into current signals ix and iy in the orthogonal stationary coordinate system 3
A phase / two-phase converter 106, a dq converter for converting the orthogonal stationary coordinate system current signals ix, iy into rotational coordinate system current signals id, iq based on the electric angle θe from the electric angle generator 104;
Reference numeral 107 denotes a current reference generator that generates current references idref and iqref for the d-axis and the q-wheel.

[0009] 108A, 108B are current references idref, i
subtracter 109 for taking the difference between qref and current signal id, iq, 109
A and 109B are PI controllers for generating voltage command signals Vd and Vq in a rotating coordinate system based on a difference between a current reference and a current signal, and 110 is an electric angle θe from the electric angle generator 104.
Is an inverse dq converter for converting the rotary coordinate system voltage command signals Vd, Vq into the orthogonal stationary coordinate system voltage command signals Vx, Vy based on the following. 111 is the orthogonal stationary coordinate system voltage command signals Vx, Vy, ^* , Vv ^* , Vw ^* , a two-phase / three-phase converter, 112 is a voltage command signal Vu ^* ,
This is a PWM circuit that generates a gate signal to the inverter based on Vv ^* and Vw ^* .

FIG. 21 shows an equivalent circuit of the PMSM. From the viewpoint of the current control system, the equivalent circuit can be represented by inductance, resistance, and induced voltage. FIG. 22 shows an example of a current response when a step-like current is given as a current reference, that is, a waveform of a step response. Here, the time from when the current command is applied to the time when the actual current reaches 95% is referred to as "response time", but another index indicating the speed of response may be used. The step response waveform depends on the inductance value and the resistance value of the equivalent circuit of the PMSM, and the constant of the PI controller of the current control system.

As described above, the inductance value changes due to magnetic flux saturation. That is, in the direction in which the N-pole of the magnetic pole and the current vector coincide, the inductance value decreases due to the influence of saturation, and in the direction different by 180 degrees, saturation does not occur and the inductance value is relatively large.

The rotor is fixed at a predetermined position, and the electrical angle is set to 0.
The response time is measured from the current step response waveform at each electrical angle while gradually changing it within the range of ２2π (rad). FIG. 23 shows an example of the measurement result.

In FIG. 23, the magnetic pole positions are 0 degrees, 90 degrees, and 180 degrees.
In each case, the inductance value is small near the magnetic pole position due to the influence of magnetic flux saturation, the response time is short, and the inductance value is relatively large in other parts, It can be seen that the response time is also longer. In addition, in the portion where the response is fast (in the direction of the magnetic pole position), the change in the response time is small even if the electric angle θe largely changes. Thus, it can be seen that the response time changes relatively largely.

The present invention pays attention to this fact, and estimates the magnetic pole position using a portion having a long response time which is sensitive to a change in the electrical angle θe. That is, in the motor constrained state, the electric angle θe is changed, and the current step response time is measured at each electric angle. Since the electrical angle θe at which the response time becomes maximum is shifted by 180 degrees from the magnetic pole position θ, 180 degrees are added to obtain the magnetic pole position θ.

[0015]

According to a first aspect of the present invention, there is provided a control apparatus for a permanent magnet synchronous motor, comprising: Measure the response time of the step response. In the vicinity of the magnetic pole position, the inductance value is small due to the influence of magnetic flux saturation, and the response time is short.On the contrary, in the direction opposite to the magnetic pole position, the inductance value is large, and the response time is long. Although the change in the response time is small, the change in the electrical angle in the direction opposite to the magnetic pole position is relatively large and the sensitivity is good. Therefore, an electric angle in the opposite direction to the magnetic pole position having the slowest response time is searched for, and an angle value obtained by adding or subtracting 180 degrees to the obtained electric angle is used as the magnetic pole position estimated value. As a result, in the control device of the permanent magnet synchronous motor having no magnetic pole position sensor, the magnetic pole position can be estimated with sufficient accuracy even when the electric motor is at rest, and a smooth start without reversal becomes possible.

In the control apparatus for a permanent magnet synchronous motor according to a second aspect of the present invention, the electric angle is changed at regular angle intervals while the permanent magnet synchronous motor is at rest, and the response of the step response of the current at each electric angle. Measure time. In the vicinity of the magnetic pole position, the inductance value is small due to the influence of magnetic flux saturation, and the response time is short.On the contrary, in the direction opposite to the magnetic pole position, the inductance value is large, and the response time is long. The change in response time is small,
In the direction opposite to the magnetic pole position, the response time changes relatively largely with respect to the change in the electrical angle, and the sensitivity is good. Therefore, an electric angle in the direction opposite to the magnetic pole position having the slowest response time is selected, and an angle value obtained by adding or subtracting 180 degrees to or from the selected electric angle is used as the magnetic pole position estimated value. As a result, in the control device of the permanent magnet synchronous motor having no magnetic pole position sensor, the magnetic pole position can be estimated with sufficient accuracy even when the electric motor is at rest, and a smooth start without reversal becomes possible.

In the control apparatus for a permanent magnet synchronous motor according to a third aspect of the present invention, the control is performed when the permanent magnet synchronous motor is at rest.
The response time of the current step response is measured at more than one electrical angle. Then, a curve passing through each of the measured points is calculated, an electrical angle at which the curve takes the maximum value is obtained, and an angle value obtained by adding or subtracting 180 degrees to the obtained electrical angle is set as a magnetic pole position estimated value. This not only selects the largest electrical angle from which the response has been obtained, but also obtains the maximum value of the curve to which data near the maximum value applies, so that the magnetic pole position can be more accurately estimated.

In the control apparatus for a permanent magnet synchronous motor according to a fourth aspect of the present invention, the electric angle is changed at regular angle intervals while the permanent magnet synchronous motor is stationary, and the response of the current step response at each electric angle. Measure time. A function having periodicity can be approximated by a Fourier series, and the electrical angle-response time characteristic can be approximated by the sum of a DC signal, a cosine wave signal of a fundamental frequency and a cosine wave signal of a double frequency. When expanded, the electrical angle at which the response time becomes maximum is tan ^-1 (the coefficient of the fundamental cosine wave term of the Fourier series / the coefficient of the fundamental sine wave term), and an angle value obtained by adding or subtracting 180 degrees to this electrical angle. Is the magnetic pole position estimated value. As a result, compared to the case where the maximum value of the response time is simply picked up, it is possible to obtain a magnetic pole position estimated value with higher accuracy only by performing simple integration.

In the control apparatus for a permanent magnet synchronous motor according to a fifth aspect of the present invention, the response time of the step response of the current is first determined at least at two electrical angles in the stationary state of the permanent magnet synchronous motor. Chooses the slowest electrical angle. At this point, the electric angle with the slowest response time is between the adjacent electric angles for which the response time was calculated with the selected electric angle as the center, so the next was obtained immediately before with the selected electric angle as the center. The response time of the step response of the current of the electrical angle is obtained with a smaller electrical angle than the electrical angle, and the electrical angle with the slowest response time is selected. This is repeated until the difference between the previous electrical angle and the current electrical angle becomes equal to or smaller than a predetermined value, and the angle value obtained by adding or subtracting 180 degrees to the latest electrical angle at that time is used as the magnetic pole position estimated value. As a result, it is not necessary to take a current response for all electrical angles set in fine steps over the entire 360 degrees, so that the search time can be greatly reduced.

In the control device for a permanent magnet synchronous motor according to claim 6 of the present invention, the response time of the current step response is as follows:
The average value is the response time of the step response of a plurality of currents taken at the same electrical angle. Thereby, the influence of the measurement error can be reduced, and the estimation accuracy can be further improved.

In the permanent magnet synchronous motor control apparatus according to a seventh aspect of the present invention, the permanent magnet synchronous motor is operated by supplying a reference signal having a constant frequency in a stationary state. In a permanent magnet synchronous motor, when a current reference signal having a constant frequency is given, since the inductance values are different between the magnetic pole direction and the other directions, the trajectories of the voltages Vx and Vy in the rectangular stationary coordinate system become elliptical trajectories, The electrical angle of the elliptical locus in the minor axis direction is the north pole direction or south pole direction of the magnetic pole position. Similarly, when a voltage reference signal having a constant frequency is given, the locus of the currents ix and iy in the rectangular stationary coordinate system becomes an elliptical locus,
The electrical angle in the major axis direction of the elliptical locus corresponds to the N pole direction or S pole direction of the magnetic pole position. In addition, since the inductance is small and the step response is fast due to magnetic flux saturation in the N pole direction of the magnetic pole, the shorter response time of the current step response at each candidate electrical angle is used as the magnetic pole position estimated value. This allows
By using high-frequency current response and current step response together, the number of trials of current step response can be reduced,
The magnetic pole position estimation time can be reduced.

In the control device for a permanent magnet synchronous motor according to the present invention, when executing the closed loop current control, a switch is switched to the current controller means, the output of which is input to the modulation signal generating means, and the open loop control is performed. Is executed, the switch is switched to the voltage reference generating means, and the output is input to the modulation signal generating means. First, when the permanent magnet synchronous motor is at a standstill, the input of the switch is switched to the current controller side to supply a current reference signal having a constant frequency to operate. In a permanent magnet synchronous motor, when a current reference signal having a constant frequency is given, the inductance values are different between the magnetic pole direction and the other direction, so that the locus of the voltages Vx and Vy in the rectangular stationary coordinate system becomes an elliptical locus, Since the electrical angle of the elliptical locus in the minor axis direction is the N pole direction or S pole direction of the magnetic pole position, the minor axis direction angle of the ellipse of the voltage locus is set to the candidate electrical angle of the magnetic pole position in the N pole direction or S pole direction. I do. Next, the input of the switch is switched to the voltage reference generating means, and the response time of the current step response when a step-like voltage reference is applied to each candidate electrical angle is measured. In the N-pole direction of the magnetic pole, the inductance is small due to magnetic flux saturation, and the step response is fast. Therefore, the shorter response time of the current step response at each candidate electrical angle is the magnetic pole position estimated value. This makes it possible to reduce the number of trials of the current step response by using both the high-frequency current response and the current step response, thereby shortening the magnetic pole position estimation time.

In the control device for a permanent magnet synchronous motor according to the ninth aspect of the present invention, when executing the closed loop current control, the switch is switched to the current controller means, the output of which is input to the modulation signal generating means, and the open loop control is performed. Is executed, the switch is switched to the voltage reference generating means, and the output is input to the modulation signal generating means. First, when the permanent magnet synchronous motor is stationary, the input of the switch is switched to the voltage reference generating means, and the motor is operated by supplying a voltage reference signal of a constant frequency. In a permanent magnet synchronous motor, when a voltage reference signal of a constant frequency is given, the locus of the currents ix and iy in the rectangular stationary coordinate system becomes an elliptical locus, and the electrical angle of the elliptical locus in the major axis direction is the magnetic pole position. Since the direction is the N-pole direction or the S-pole direction, the major-axis angle of the ellipse of the current locus is set as the candidate electrical angle of the magnetic pole position in the N-pole direction or the S-pole direction. Next, the input of the switch is switched to the current controller means side, and the response time of the step response of the current when a step-like current reference is given to each candidate electrical angle is measured.
In the N-pole direction of the magnetic pole, the inductance is small due to magnetic flux saturation, and the step response is fast. Therefore, the shorter response time of the current step response at each candidate electrical angle is the magnetic pole position estimated value. This makes it possible to reduce the number of trials of the current step response by using both the high-frequency current response and the current step response, thereby shortening the magnetic pole position estimation time.

In the control apparatus for a permanent magnet synchronous motor according to a tenth aspect of the present invention, the variable voltage variable frequency AC power supply is an inverter, and the inverter is controlled by a closed loop current control system.

In the control apparatus for a permanent magnet synchronous motor according to the present invention, the variable voltage variable frequency AC power supply is an inverter, and the inverter is controlled by an open loop control system.

In the control device for a permanent magnet synchronous motor according to a twelfth aspect of the present invention, the frequency of the current reference signal or the voltage reference signal is set higher than the rated frequency of the permanent magnet synchronous motor. Then, the mechanical inertia cannot follow the change in the generated torque and remains stationary. Therefore, the magnetic pole position is estimated using the electrical characteristics at this time.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram for explaining an algorithm for estimating a magnetic pole position at start according to the first embodiment of the present invention. In FIG. 1, a rectangle indicates a calculation process in the estimation algorithm, and a diamond indicates a condition determination process.

Process 1 is a response time maximum value search variable τmax
And a variable θemax that stores the electrical angle at which the response time becomes maximum. Processes 2, 7, and 8 are processes and determinations for executing processes in the roof while incrementing the number N from 0 to NX-1 by one. For example,
When NX = 64, the range of 360 degrees is searched for while increasing the electrical angle by 5.625 degrees.

In the process 3, the electrical angle θe corresponding to the number N is calculated. In process 4, a step-like current command value is given to the PMSM current control system at the electrical angle θe to obtain step response data, and a response time τ is calculated.

In processes 5 and 6, the response time τ at the current electrical angle θe is compared with the maximum value τmax of the response time up to that time. If τ is larger, τmax is updated by τ. The electric angle θemax at the time of taking the maximum value is also updated to θe.

At the time when the loop is completed and the processing goes down from the processing 8, the electric angle at which the response time becomes maximum within the range of 360 degrees is recorded in the θemax. By adding (πrad), the magnetic pole position 9 is calculated.

As described above, since the magnetic pole position can be estimated with sufficient accuracy even in the absence of the magnetic pole position sensor, a smooth start is possible, and no sensor is required.
An inexpensive and highly reliable control device for a permanent magnet synchronous motor can be configured.

Next, a second embodiment will be described.
FIG. 2 is a diagram for explaining an algorithm for estimating a magnetic pole position at start according to the second embodiment of the present invention. In FIG. 2, FIG.
The same reference numerals denote the same components.

In FIG. 2, the current step response is obtained while changing the electrical angle little by little, and the maximum value of the response time is obtained in the same manner as in the embodiment shown in FIG. However, the loop counter N when the response time takes the maximum value is recorded as Nmax. Also, a set of response times at each electrical angle is recorded. After the loop is completed, in step 12, the electrical angle at which the response time is maximized and the electrical angles before and after the electrical angle are obtained.

[0035]

(Equation 1)

Then, a parabola passing through these three points is obtained by using the data of the response times τ1, τ2, and τ3 at the respective electrical angles. Next, in process 13, the electrical angle θemax at which the parabola takes the maximum value is determined. Here, a maximum value search method using parabolic approximation will be described with reference to FIG. With respect to the response times τ1, τ2, τ3 of the current step response at the electrical angles θe1, θe2, θe3, the equation representing the parabola passing through these three points is

[0037]

(Equation 2) Becomes The electrical angle at which this parabola takes the maximum value is

[0038]

(Equation 3) Can be calculated by Thus, in the present embodiment,
In addition to selecting the largest electrical angle from which the response was taken, the maximum value of the curve to which data near the maximum value applies is obtained, so that the magnetic pole position can be more accurately estimated. Although an example of approximation using a parabola has been described here, it goes without saying that another curve may be used.

Next, a third embodiment of the present invention will be described. FIG. 4 is a view for explaining an algorithm for estimating a magnetic pole position at start according to the third embodiment of the present invention. Before explaining FIG. 4, the principle of the present embodiment will be described. Generally, a function having periodicity can be approximated by a Fourier series. The general formula for the Fourier series and its coefficients is:

[0040]

(Equation 4)

When observing the electrical angle-response time characteristic shown in FIG. 23, this characteristic shows that a DC signal and a cosine wave signal of a fundamental frequency,
Further, it can be seen that the approximation can be made by the sum of the cosine wave signals of the double frequency.

[0042]

Τ (θe) = α0 + α1 × cos (θe−θem)
ax) + α2 × cos (2 (θe−θemax))

[0043]

Τ (θe) = α0 + α1 × cos (θemax) ×
cos (θe) + α1 × sin (θemax) × sin (θ
e) + α2 × cos (2θemax) × cos (2θe) +
α2 × sin (2θemax) × sin (2θe) On the other hand, from the Fourier series and its coefficient calculation formula,

[0044]

(Equation 7) Therefore, the electrical angle that maximizes the response time is

[0045]

(Equation 8) Can be calculated by The embodiment shown in FIG. 4 is based on the above principle, and performs the numerical integration of the above equation using the data of the electric angle-response time characteristic to obtain the electric angle θemax at which the response time takes the maximum value. is there.

In FIG. 4, the components denoted by the same reference numerals as those in FIG. 1 indicate the same components, and the description will be omitted. In FIG. 4, in a process 14, variables SumA1 and Sum for integration are set.
B1 is initialized (cleared to zero). Within the loop, take the current step response while gradually changing the electrical angle,
The response time 7 is measured.

In the process 15, the integral part of the above equation is executed discretely. The trapezoidal formula, Simpson formula,
There are various methods, but here we use the simplest rectangle formula.

[0048]

SumA1 = SumA1 + τ × sin (θe) × Δθ SumB1 = SumB1 + τ × cos (θe) × Δθ Δθ = 2π / NX After the loop is completed,

[0049]

(Equation 10) Calculate the coefficients α1 and b1. In process 17,

[0050]

[Equation 11] To calculate θemax. Then, in processing 9, 1 is added to θemax.
By adding 80 degrees, a magnetic pole position estimated value θ can be obtained.

According to the present embodiment, it is possible to obtain a magnetic pole position estimated value with higher accuracy only by performing simple integration as compared with a case where the maximum value of the response time is simply picked up. In addition, since response time data over the entire 360 degrees is used, there is also a feature that it is hardly affected by measurement errors.

Next, a fourth embodiment of the present invention will be described. FIG. 5 is a diagram for explaining the starting magnetic pole position estimation algorithm according to the fourth embodiment of this invention.

In FIG. 5, in process 21, the electrical angle 45
The current step response is taken every degree, the response time is measured, and the angle θemax1 that takes the maximum value is selected. At this point, the electrical angle θemax to be obtained is in the section [θemax1−45 °, θemax +
45 °], the next step is to narrow down the search to this section.

In step 22, θemax1 -22.5 °, θ
The current step response at emax1 + 22.5 ° is taken, the response time is measured, and θemax1, θemax1-22.5 °, θe
The angle θemax2 that takes the maximum value of the three response times at max1 + 22.5 ° is selected.

In the same manner, the search section is narrowed down, and processing 2
In the case of 3, θemax2 -11.25 °, θemax2 +11.2
Take the current step response at 5 °, measure the response time,
θemax2, θemax2 -11.25 °, θemax2 +11.
Angle θem that takes the maximum value of the three response times at 25 °
Select ax3.

In the process 24, θemax3−5.62
The current step response at 5 ° and θemax3 + 5.625 ° is taken, the response time is measured, and θemax3 and θemax3−5.6.
The angle θemax4 which takes the maximum value of the three response times at 25 ° and θemax3 + 5.625 ° is selected.

When the search section becomes sufficiently narrow, the search is terminated, and 180 degrees are added to the electrical angle obtained in the process 25 to obtain a magnetic pole position estimated value. According to the present embodiment, since it is not necessary to take a current response for all electrical angles set in fine steps over 360 degrees, the search time can be greatly reduced.

Next, a fifth embodiment of the present invention will be described. FIG. 6 is a view for explaining an example of the magnetic pole position estimation algorithm at the time of starting according to the fifth embodiment of the present invention.
In FIG. 6, those denoted by the same reference numerals as those in FIG.

In FIG. 6, in a process 26, the current step response is taken four times, and the response times τ1, τ2, τ3, τ4 are measured. In process 27, the average value τav of those response times
Calculate e.

[0060]

(Equation 12) In processing 28, the maximum value τmax of the response time up to the previous electrical angle is compared with the average response time τave at the current electrical angle, and if τave is larger, τave is set as the maximum response time in processing 29. Then, θe is registered as the electrical angle that takes the maximum value of the response time.

Also in the present embodiment, the magnetic pole position can be estimated using the relationship between the electrical angle and the response time. Moreover, since the current step response is tried a plurality of times and the average value is obtained, the influence of the measurement error can be reduced, and the estimation accuracy can be further improved.

Here, the embodiment in which the average value is calculated by taking the current step response four times has been described. However, it is needless to say that the average value may be calculated not only four times but generally M times.
Further, here, the example of using the average value of the response time has been described for the example of searching for the maximum value of the response time. However, the embodiment of the curve fitting, the embodiment of calculating the Fourier series coefficient, and the range of the electrical angle to be searched are described. It is needless to say that the average value of the response time can also be used in the embodiment in which is gradually reduced.

Next, another embodiment of the present invention will be described. FIG. 7 shows a block diagram of another control system capable of checking the response of the PMSM. In FIG. 7, the components denoted by the same reference numerals as those in FIG. 20 indicate the same components.

In FIG. 7, reference numeral 113 denotes a voltage reference generator for generating voltage reference signals Vdref and Vqref in a rotating coordinate system. Inverse dq converter 110 and 2-phase / 3-phase converter 111
Converts the voltage reference signals Vdref, Vqref of the rotating coordinate system into voltage command signals Vu ^* , Vv ^* , Vw ^* of the stationary coordinate system according to the electric angle θe generated by the electric angle generator 104.

The PWM circuit 112 has a voltage command signal Vu ^* ,
A firing signal to the inverter is generated based on Vv ^* and Vw ^* . The PWM inverter 101 and the PMSM 102 operate according to their dynamic characteristics, and an output current flows. The output current is detected by the current detectors 103A and 103B,
The three-phase / two-phase converter 105 and the dq converter 106 convert the current signals into current signals id and iq in a rotating coordinate system. Therefore, current response data when the voltage reference generator 113 generates a step-like voltage signal can be obtained.

Also in this control system, response data can be obtained by gradually changing the electrical angle, and the response time can be calculated. In the direction in which the current vector coincides with the direction of the magnetic pole, the inductance is reduced due to the effect of magnetic saturation and the response time is short, and the response time is long in the direction opposite to the magnetic pole position. Is the same as in the case of the current step response.

The embodiments shown in FIGS. 8 to 12 utilize this open loop current response. FIG. 8 shows a sixth embodiment of the present invention, in which a voltage step reference is given at each electrical angle while changing the electrical angle little by little at a constant interval, and the magnetic pole position is estimated from the response time of the current response. Is what you do. Processing 4 for measuring the response time of the current step response of the closed roof current control system in FIG.
However, in FIG. 8, the process is replaced with a process 41 for measuring the current response time in the open loop, and the rest is the same as the embodiment of FIG.

FIG. 9 shows a seventh embodiment of the present invention, in which a magnetic pole position is estimated by using a parabola passing through three points of data before and after the electrical angle which is the largest among the response time data. . The process 4 for measuring the response time of the current step response in FIG. 2 is replaced with the process 41 for measuring the current response time in the open loop in FIG. 9, and the other points are the same as those in the embodiment of FIG. Is omitted.

FIG. 10 shows an eighth embodiment of the present invention, in which magnetic pole positions are estimated from Fourier series coefficients. The processing 4 for measuring the response time of the current step response in FIG. 4 is replaced with the processing 41 for measuring the current response time in the open loop in FIG. 10, and the other points are the same as those in the embodiment of FIG. Is omitted.

FIG. 11 shows a ninth embodiment of the present invention, in which the magnetic pole position is estimated by gradually narrowing the range of the electrical angle for obtaining response data. Processing 21 to 24 for measuring response time of current step response in FIG.
However, in FIG. 11, the processes 42 to 45 for measuring the current response time in the open loop are replaced with those in FIG.
The description is omitted because it is the same as that of the embodiment.

FIG. 12 shows a tenth embodiment of the present invention, in which an average value of response data is used. Processing 26 for measuring the response time of the current step response in FIG.
However, in FIG. 12, the processing is replaced with the processing 46 for measuring the current response time in the open loop, and the other parts are the same as those in the embodiment of FIG.

Also in these embodiments, since the magnetic pole position at the time of starting the PMSM can be estimated without a magnetic pole position sensor, a smooth start without reverse rotation is possible.

Next, the operating principle of another embodiment of the PMSM magnetic pole position estimation will be described with reference to FIG. In general, when a current equal to or higher than the rated frequency is applied to a stationary PMSM, mechanical inertia cannot follow a change in generated torque, and the PMSM remains stationary. Using this, there is a method of estimating the magnetic pole position using electrical characteristics when a high-frequency current is applied. An example will be described below.

In the current control system block diagram of FIG.
The current reference generator 107 outputs a constant reference value, and the electrical angle generator 104 generates an electrical angle based on a frequency higher than the rated frequency.

The current control system determines the current feedback value id,
Since iq moves so as to follow the current references idref and iqref, id and iq coincide with idref and iqref in a steady state, and the locus of ix and iy in the rectangular stationary coordinate system is a circle.
On the other hand, in the PMSM, the values of the inductances in the equivalent circuit of FIG. 21 are different between the magnetic pole direction and the other directions, so that ix and iy in the rectangular stationary coordinate system have elliptical trajectories as shown in FIG. The direction of the magnetic pole can be calculated by obtaining the angle θr of the elliptical locus in the minor axis direction. However, at this stage, it cannot be determined whether it is an N pole or an S pole.

Next, the electrical angle is fixed in the direction of the angle θr,
A step-like current reference is given and its response time is measured. Similarly, the electrical angle is fixed in the direction of the angle θr + 180 degrees, and the response time of the current step response is measured. Figure 1 already
As described in the embodiment of FIG. 6, since the inductance is small and the response is fast due to the magnetic flux saturation in the N-pole direction of the magnetic pole, the response time at the above angle θr and the angle θr + 180
The shorter one of the response times in degrees may be the N pole.

FIG. 14 shows an eleventh embodiment of the present invention based on this principle. In a process 61, a current reference having a constant frequency and a constant amplitude is given to the PMSM current control system, and the minor axis direction angle θr of the ellipse is measured from the locus of Vx and Vy in the orthogonal stationary coordinate system at that time.

In steps 62 and 63, the response time τ1 is measured from the step response of the current control system at the electrical angle θr. In steps 64 and 65, the response time .tau.2 is measured from the step response of the current control system at the electrical angle .theta.r +180 degrees.

In the condition judgment 66 and the processes 67 and 68, the response time τ1 measured in the process 63 and the response time τ2 measured in the process 65 are compared, and the electrical angle when the response time is short is adopted as the magnetic pole position θ.

According to the present embodiment, the number of trials of the current step response can be reduced by using both the high-frequency current response and the current step response, so that the magnetic pole position estimation time can be further reduced.

In the example of FIG. 14, the angle of the elliptical trajectory in the minor axis direction is obtained. However, it is needless to say that the angle θr2 of the major axis direction can be obtained and the current step response at θr2 + 90 degrees and θr2-90 degrees can be taken. .

FIG. 15 shows a twelfth embodiment of the present invention. In the present embodiment, the embodiment of FIG. 14 provides a current reference with a constant frequency and a constant amplitude to the PMSM current control system shown in FIG. 20, and Vx in the orthogonal stationary coordinate system at that time.
, Vy are made elliptical, while the current ix of the rectangular stationary coordinate system when a high-frequency voltage reference having a constant amplitude is given using the open loop control system of FIG.
, Iy are made elliptical. In this case, the major axis direction is the magnetic pole direction.

In step 69, the magnetic pole direction θr is calculated from the current locus. Next, in processes 62 and 70, the electrical angle θ
The response time τ1 is measured from the current response when the step voltage reference is given by r.

In processes 64 and 71, the electrical angle θr + 180
The response time τ2 is measured from the current response when a step-like voltage reference is given in degrees. Condition judgment 66 and processing 67, 6
Reference numeral 8 is the same as that of the embodiment of FIG. 14, and the electrical angle having the shorter response time is adopted as the magnetic pole position θ.

Next, another embodiment will be described. In this embodiment, the control system shown in FIG. 16 is used. In FIG. 16, the same reference numerals as in FIGS. 7 and 20 denote the same components, and a description thereof will not be repeated.

Referring to FIG. 16, reference numeral 114 denotes a switch. Outputs Vd and Vq of the Pl controllers 109A and 109B are connected to the input of the inverse dq converter 110 when executing the closed roof current control. When performing open loop control, the outputs Vdref and Vqref of the voltage reference generator 113 are connected to the inputs of the inverse dq converter 110.

In the thirteenth embodiment of FIG. 17, at the stage of processing 61, the switch 114 of FIG. 16 is connected to the closed loop current control system side. A current reference having a constant frequency and a constant amplitude is given to the PMSM current control system, and the minor axis direction angle θr of the ellipse is measured from the locus of Vx and Vy in the orthogonal stationary coordinate system at that time.

Next, in the processing 62 and thereafter, the switch 1 shown in FIG.
Reference numeral 14 is connected to the open loop control side, and in processes 62 and 70, the response time τ1 is measured from the current response when a step-like voltage reference is given at the electrical angle θr.

In processes 64 and 71, the electrical angle θr + 180
The response time τ2 is measured from the current response when a step-like voltage reference is given in degrees. Condition judgment 66 and processing 67, 6
8 is the same as that of the embodiment of FIG. 14, and the electrical angle having the shorter response time is adopted as the magnetic pole position θ.

FIG. 18 shows a fourteenth embodiment of the present invention. The control system of FIG. 16 is also used in the present embodiment. In FIG. 18, at the stage of processing 69, the switch 114 of FIG. 16 is connected to the open-loop control side, and the elliptic trajectory of the currents ix and iy of the orthogonal stationary coordinate system when a high-frequency voltage reference with a constant amplitude is given is used. Long axis direction angle θr
Is measured.

Next, in the processing 62 and thereafter, the switch 1 shown in FIG.
14 is connected to the closed loop control side, and in processes 62 and 63, the response time τ1 is measured from the current control system step response at the electrical angle θr.

In processes 64 and 71, the electrical angle θr + 180
The response time τ2 is measured from the current control system step response in degrees. The condition judgment 66 and the processes 67 and 68 are the same as those in the embodiment of FIG. 14, and the electrical angle having the shorter response time is adopted as the magnetic pole position θ.

Also in these embodiments, by using the high-frequency current response and the current step response together, the number of trials of the current step response can be reduced, so that the magnetic pole position estimation time can be further shortened. The same is true. Needless to say, there may be an embodiment using an average of a plurality of response times in calculating the response time of the current response.

[0094]

As described above, according to the present invention, the position of the magnetic pole at the time of starting the PMSM is estimated by using the electrical angle-response time characteristic, and a smooth start without reversal is possible. Since a position sensor is not required, an inexpensive and high-performance PMSM drive system can be configured.

[Brief description of the drawings]

FIG. 1 is a flowchart of a first embodiment of the present invention.

FIG. 2 is a flowchart according to a second embodiment of the present invention.

FIG. 3 is a diagram illustrating the principle of curve fitting using a parabola.

FIG. 4 is a flowchart according to a third embodiment of the present invention.

FIG. 5 is a flowchart according to a fourth embodiment of the present invention.

FIG. 6 is a flowchart according to a fifth embodiment of the present invention.

FIG. 7 is a block diagram of an open loop control system.

FIG. 8 is a flowchart according to a sixth embodiment of the present invention.

FIG. 9 is a flowchart according to a seventh embodiment of the present invention.

FIG. 10 is a flowchart according to an eighth embodiment of the present invention.

FIG. 11 is a flowchart according to a ninth embodiment of the present invention.

FIG. 12 is a flowchart according to the tenth embodiment of the present invention.

FIG. 13 is a diagram showing a current / voltage locus during high-frequency current control.

FIG. 14 is a flowchart according to an eleventh embodiment of the present invention.

FIG. 15 is a flowchart according to a twelfth embodiment of the present invention.

FIG. 16 is a block diagram of a closed loop / open loop switching control system.

FIG. 17 is a flowchart according to a thirteenth embodiment of the present invention.

FIG. 18 is a flowchart according to a fourteenth embodiment of the present invention.

FIG. 19 is a diagram showing a relationship between a magnetic pole position and a current vector.

FIG. 20 is a block diagram of a closed loop current control system.

FIG. 21 is a diagram showing an equivalent circuit of a permanent magnet synchronous motor.

FIG. 22 is a diagram showing a definition of a response time.

FIG. 23 is a diagram showing a current step response time at each magnetic pole position.

[Explanation of symbols]

 101: inverter 102: PMSM 103A, 103B: current sensor 104: electric angle generator 105: three-phase / two-phase converter 106: dq converter 107: current reference Generator 108A, 108B ... Subtractor 109A, 109B ... Pl controller 110 ... Inverse dq converter 111 ... 2 phase / 3 phase converter 112 ... PWM circuit 113 ... Voltage reference generation Container 114 ・ ・ ・ Switch

Claims (12)

[Claims] 1. A control device for a permanent magnet synchronous motor that drives a permanent magnet synchronous motor using a variable voltage variable frequency AC power supply, wherein a step response of a current at a plurality of electrical angles is obtained at a stationary state of the permanent magnet synchronous motor. A control device for a permanent magnet synchronous motor, characterized in that a response time is measured, an electric angle having the slowest response time is searched, and an angle value obtained by adding or subtracting 180 degrees from the obtained electric angle is used as an estimated magnetic pole position value. . 2. A control apparatus for a permanent magnet synchronous motor that drives a permanent magnet synchronous motor using a variable voltage variable frequency AC power supply, wherein the electric angle is changed at regular angle intervals while the permanent magnet synchronous motor is stationary. Measure the response time of the current step response at each electrical angle, select the electrical angle with the slowest response time, and use the angle value obtained by adding or subtracting 180 degrees to the selected electrical angle as the magnetic pole position estimated value. Characteristic control device for permanent magnet synchronous motor. 3. A permanent magnet synchronous motor control device for driving a permanent magnet synchronous motor using a variable voltage / variable frequency AC power supply, wherein the permanent magnet synchronous motor is driven in a stationary state.
Measure the response time of the current step response at more than one electrical angle, calculate the curve to which the response time data fits,
The electric angle at which the curve takes the maximum value is obtained, and the obtained electric angle is 18
A control device for a permanent magnet synchronous motor, wherein an angle value obtained by adding or subtracting 0 degrees is used as a magnetic pole position estimated value. 4. A permanent magnet synchronous motor control device for driving a permanent magnet synchronous motor using a variable voltage variable frequency AC power supply, wherein the electric angle is changed at regular angle intervals while the permanent magnet synchronous motor is stationary. Measure the response time of the step response of the current at each electrical angle, calculate the coefficients of the fundamental cosine wave term and the fundamental sine wave term of the Fourier series that approximate the electrical angle-response time characteristics, and calculate their relationship. A control device for a permanent magnet synchronous motor, wherein a magnetic pole position is estimated from numerical values. 5. A permanent magnet synchronous motor control device for driving a permanent magnet synchronous motor using a variable voltage / variable frequency AC power supply, wherein the permanent magnet synchronous motor is initially stationary at least at two electrical angles in a stationary state. Find the response time of the step response, select the electrical angle with the slowest response time,
The electrical angle taking the next current response is sequentially determined around the selected electrical angle, the response time of the step response of the current of the selected electrical angle and the current of the newly determined electrical angle is determined, and the response time is the slowest. The electric angle is selected, and the electric angle is obtained by terminating the search when the difference between the previous electric angle and the current electric angle becomes a predetermined value or less, and adding or subtracting 180 degrees to the obtained electric angle to the magnetic pole. A control device for a permanent magnet synchronous motor, wherein the control device is a position estimation value. 6. The response time of the step response of the current is:
The control device for a permanent magnet synchronous motor according to any one of claims 1 to 5, wherein the average value is a response time of step responses of a plurality of currents taken at the same electrical angle. 7. A control device for a permanent magnet synchronous motor that drives a permanent magnet synchronous motor using a variable voltage / variable frequency AC power supply when the permanent magnet synchronous motor is operated by supplying a reference signal of a constant frequency in a stationary state. A candidate electric angle in the N-pole direction or S-pole direction of the magnetic pole position is obtained from the voltage locus or the current locus, and the shorter response time of the current step response at each candidate electric angle is used as the magnetic pole position estimated value. For permanent magnet synchronous motor. 8. A permanent magnet synchronous motor control device for driving a permanent magnet synchronous motor using an inverter, wherein the inverter control means includes at least a current reference generation means for generating a current reference signal for the inverter; Voltage reference generating means for generating a voltage reference signal;
Current detection means for detecting an output current of the inverter;
Electrical angle generating means for generating an electrical angle of the inverter;
Current controller means for controlling the output current to follow the current reference signal, and a switch for switching between the output of the current controller means and the voltage reference signal,
A modulation signal generating means for generating a modulation signal in accordance with the output of the switch and the electrical angle; and a P which performs pulse width modulation in accordance with a modulation signal output from the modulation signal generation means.
WM means, and means for amplifying a gate signal from the PWM means to drive an inverter element, wherein the input of the switch is switched to the current controller means side when the permanent magnet synchronous motor is in a stationary state, and a constant frequency The short-axis direction angle of the ellipse of the voltage locus when the current reference signal is applied and the operation is performed is set as a candidate electrical angle in the N-pole direction or the S-pole direction of the magnetic pole position, and the input of the switch is switched to the voltage reference generating means side. A control device for a permanent magnet synchronous motor, wherein a shorter one of a response time of a step response of a current when a step voltage reference is applied to a candidate electrical angle is used as a magnetic pole position estimated value. 9. A permanent magnet synchronous motor control device for driving a permanent magnet synchronous motor using an inverter, wherein the inverter control means includes at least a current reference generating means for generating a current reference signal for the inverter; Voltage reference generating means for generating a voltage reference signal;
Current detection means for detecting an output current of the inverter;
Electrical angle generating means for generating an electrical angle of the inverter;
Current controller means for controlling the output current to follow the current reference signal, and a switch for switching between the output of the current controller means and the voltage reference signal,
A modulation signal generating means for generating a modulation signal in accordance with the output of the switch and the electrical angle; and a P which performs pulse width modulation in accordance with a modulation signal output from the modulation signal generation means.
WM means, and means for amplifying a gate signal from the PWM means to drive an inverter element, wherein the input of the switch is switched to the voltage reference generating means side when the permanent magnet synchronous motor is in a stationary state. The major axis angle of the ellipse of the current locus of the current locus when the operation is performed by applying the voltage reference signal is set as a candidate electrical angle in the N-pole direction or the S-pole direction of the magnetic pole position, and the input of the switch is switched to the current controller means side. A control device for a permanent magnet synchronous motor, wherein a shorter response time of a step response of a current when a step current reference is given to an electric angle is used as a magnetic pole position estimated value. 10. The variable voltage / variable frequency AC power supply is an inverter, the inverter control means includes at least a current reference generation means for generating a current reference signal for the inverter, and a current detection means for detecting an output current of the inverter. Electrical angle generating means for generating an electrical angle of the inverter; current controller means for controlling the output current to follow the current reference signal; and a modulation signal according to the output of the current controller means and the electrical angle. And PWM means for performing pulse width modulation in accordance with a modulation signal output from the modulation signal generation means, and means for amplifying a gate signal from the PWM means to drive an inverter element. The control device for a permanent magnet synchronous motor according to any one of claims 1 to 7, comprising: . 11. The variable voltage variable frequency AC power supply is an inverter, and the control means of the inverter includes a voltage reference generating means for generating at least a voltage reference signal of the inverter, and a current detecting means for detecting an output current of the inverter. An electrical angle generating means for generating an electrical angle of the inverter, a modulation signal generating means for generating a modulation signal according to the voltage reference signal and the electrical angle, and a modulation signal output from the modulation signal generation means. 8. The permanent memory according to claim 1, further comprising: PWM means for performing pulse width modulation by means of a pulse signal, and means for amplifying a gate signal from said PWM means to drive an inverter element. Control device for magnet synchronous motor. 12. The permanent magnet synchronous motor according to claim 7, wherein a frequency of the current reference signal or the voltage reference signal is higher than a rated frequency of the permanent magnet synchronous motor. Control device.