JP2006025548A - Control device for generator, and method for setting control operation constant of the control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device that can accurately measure the Rs and Ls of a motor, irrespective of a capacity of the motor. <P>SOLUTION: The control device that controls the motor in terms of a variable voltage and a variable frequency, by using an inverter 1 of the motor 2 comprises a means 10 that measures a constant of the motor, controls an output frequency f1 of output torque iq to zero, accumulatively adds the motor winding resistance value Rs to the product of the current value id and the voltage value Vd, obtains the added value by dividing it with an accumulated and added value of the square value of the current id, accumulatively adds the inductance value Ls to a product of an accumulated and added value of the voltage value Vd and the current id; and measures the accumulated and added value, by dividing a square value of the current id with the accumulated and added value. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control calculation constant setting method for an AC motor control apparatus that can measure the control constant with high accuracy even in a large-capacity motor with a small impedance and set the control calculation constant in the control apparatus for the AC motor. is there.

As a conventional technique, a DC current is passed through the motor, the motor winding resistance is measured from the relationship between the voltage detection value or voltage command value and the current value, and the voltage (or current) is applied stepwise, and the current at that time There is a method in which an electrical time constant is measured from a change in voltage (or voltage), and an inductance is measured from the measured value and the previously measured resistance. (See Patent Document 1).
FIG. 4 is a configuration diagram of the “variable speed device” disclosed in Patent Document 1. First, as a direct current test, (1) the phase of the output current of the power converter 102 is set to a certain phase with the motor 101 stopped. The DC current command unit 107 switches the setting of the DC current I to four types of I1, I1 / 2, -I1, and -I1 / 2. The voltage measurement unit 108 measures the U, V, and W phase voltages of the output voltage of the power converter 102 based on these current commands, and the voltage detection unit 109 obtains the rotation coordinate voltages V1d and V1q from the measured values. In this case, the output voltage command of the current control system 103 may be used instead.
FIG. 5 shows a graph of such current command and output voltage. Here, the slope of the measurement point becomes the primary resistance R1 component of the equivalent circuit, and is obtained by the primary resistance calculation means 110.

Next, (2) as a no-load operation / zero current test, the speed control system 104 performs no-load operation of the motor 101, and in this state, the previous torque shaft voltage V1q is obtained, and from this voltage, the torque component current I1q and The voltage drop due to the primary resistance R1 of the motor is subtracted to determine the speed electromotive force E1q, the output of the excitation current command means 106 is adjusted so that E1q matches the design value, and the excitation current I1d during no-load operation is converged Let In an operation state at a constant no-load speed with these excitation currents as command values, the excitation inductance M ′ and the equivalent leakage inductance Lσ are determined from the voltage change of the motor 101 when the supply current to the motor is changed to zero stepwise. Then, the secondary time constant τ2 can be obtained. FIG. 6 shows measurement waveforms of the output voltage and the d-axis and q-axis components of the current when stepped to zero current during no-load operation. The current becomes zero for both the d-axis and the q-axis, and the q-axis voltage undergoes a voltage drop corresponding to Lσ when the current command changes, and then exponential decay corresponding to the secondary time constant τ 2 occurs.
These relationships are
E1d0 = V1d−R1 · I1d, E1q0 = V1q (Lσ) d = (E1q−E2q) / (I1d · ω1),
(M ′) d = E2q / (I1d · ω1).
For zero current control, with the electric power converter (inverter) 102 and the motor 101 connected, a voltage output identical to the induced voltage of the motor 101 is output from the inverter 102 and the potential difference is set to zero. can do.

Japanese Patent Laid-Open No. 07-75399 (FIGS. 2, 3, and 6)

However, in the case of the conventional patent document 1, when measuring the motor constant, the current value is limited to a value below the motor rating by a current controller or the like. Since the magnitude of the voltage value depends on the motor impedance, since the large-capacity motor has a small impedance, the voltage detection value or the voltage command value is a very small value.
Therefore, the ratio between the actual voltage value and the detection error value, that is, the S / N ratio, is difficult to accurately measure constants, and there is a problem that the control performance of the control device in which the constants are set is deteriorated. The present invention has been made to solve such problems, and it is an object of the present invention to provide a control device and method capable of accurately measuring a motor winding resistance value and an inductance irrespective of the capacity of the motor.

In order to solve the above-mentioned problems, the invention described in claim 1 is a control device that controls an AC motor with variable voltage and variable frequency by using an inverter, and includes means for measuring a motor constant of the motor, and the motor constant measuring means includes: Means for controlling the output frequency or output torque of the motor to zero, the motor winding resistance value is cumulatively added to the product of the current value and the voltage value, and the cumulative added value is a value obtained by cumulatively adding the square value of the current. Means for dividing and measuring, and means for measuring the inductance by cumulatively adding the product of the cumulative value of the voltage value and the current value, and dividing the cumulative value by the value obtained by cumulatively adding the square value of the current. It is characterized by that.
According to a second aspect of the present invention, the control device detects a current supplied to the AC motor, and converts the current supplied to the AC motor into an excitation current detection value and a torque current detection value. A coordinate conversion circuit that converts and outputs, an excitation current control circuit that controls the excitation current direction voltage so that the excitation current command value and the excitation current detection value match, and the torque current command value and the torque current detection A torque current control circuit for controlling the torque current direction voltage so that the values match, a phase angle calculation circuit for calculating a phase angle obtained by integrating a given output frequency command, the excitation current control circuit, An output voltage calculation circuit for calculating the magnitude and phase of the output voltage from the voltage command output from the torque current control circuit, the output frequency command value or the torque current indicator Set the value to zero, in a state in which the output frequency or the torque current is controlled to zero, is characterized by measuring the motor parameters.
According to a third aspect of the present invention, in the control arithmetic constant setting method, in the measurement method, the motor winding resistance value sets the excitation current command value to a fixed value or a slowly changing value, and the excitation current The motor constant is measured in a state in which the excitation current command value and the excitation current detection value are controlled to coincide with each other by a control circuit.
According to a fourth aspect of the present invention, in the control operation constant setting method, the inductance value of the measurement method is set to a value at which the excitation current command value changes periodically and the cycle integral becomes zero, The motor constant is measured in a state in which the excitation current command value and the excitation current detection value are controlled to coincide with each other by the excitation current control circuit according to claim 2.
According to a fifth aspect of the present invention, in the control arithmetic constant setting and setting method according to the first aspect, the motor constant measuring means automatically controls the output frequency to zero when the torque current detection value is not zero. It is characterized by having means to do.
The invention according to claim 6 comprises the control calculation constant setting method according to claims 1 to 5, and controls the control constant measured by the measurement method or the constant calculated using the control constant. It is characterized by being set in the device.
According to a seventh aspect of the present invention, in the control apparatus for an AC motor according to the sixth aspect, when measuring the motor winding resistance value and the inductance value, the output frequency command value and the torque current command are set to zero. Then, the excitation current command value is set to a fixed value or a slowly changing value, the product of the current value id and the voltage value Vd detected every predetermined sampling period is cumulatively added, and the cumulative addition value is squared of the current id. Measure the motor winding resistance value by dividing the value by the cumulative addition value, switch to the inductance measurement mode, change the excitation current command value periodically, and set the cycle integral to a value that becomes zero, An electric motor constant calculator for measuring the inductance value by cumulatively adding the product of the cumulative addition value of the voltage value Vd and the current value id and dividing the cumulative addition value by the value obtained by cumulatively adding the square value of the current id. It is characterized in that.

  According to the present invention, the resistance value of the motor is measured by cumulatively adding the product of the current value and the voltage value, and dividing the value by the cumulative addition value of the square of the current, and the inductance is the cumulative addition value of the voltage value. Accumulated addition of the product of the current values, and dividing the value by the cumulative addition value of the square of the current value enables measurement of the motor winding resistance value and inductance with high accuracy regardless of the capacity of the motor. There is an effect.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing an example of an embodiment of a control device for an AC motor according to the present invention.
In FIG. 1, the motor control device includes an inverter 1, an AC motor 2, a current detector 3, a current coordinate conversion circuit 4, a torque current control circuit 5, an excitation current control circuit 6, a phase calculation circuit 7, and an output voltage calculation circuit 8. A switching pattern generation circuit 9, an electric motor constant calculator 10, and an output frequency corrector 11. The inverter 1 converts a DC voltage obtained by converting a three-phase AC input into a DC by a power element into an AC having an arbitrary frequency and voltage by a PWM control method and supplies the AC voltage to the AC motor 2. The current detector 3 detects a current supplied to the AC motor 2.
The current coordinate conversion circuit 4 separates the current detected by the current detector 3 into a torque current detection value iqfb and an excitation current detection value idfb.
The torque current control circuit 5 calculates the first q-axis voltage command value Vqref so that the given torque current command value iqref and the torque current detection value iqfb match. The excitation current control circuit 6 calculates the d-axis voltage command value Vdref so that the given excitation current command value idref and the excitation current detection value idfb match. The phase calculation circuit 7 calculates the phase θ by integrating the given frequency f1.
The output voltage calculation circuit 8 outputs an output voltage command value V1 and its voltage phase θv from the q-axis voltage command value Vqref and the d-axis voltage command value Vdref. The switching pattern generation circuit 9 determines the switching pattern of the inverter 1 from the output voltage command value V1 and the power converter output phase θdeg obtained by adding the voltage phase θv and the phase θ.

V1 = {(Vdref) ² + (Vqref) ² } ^1/2 (a)
θv = tan ⁻¹ (Vqref / Vdref) (b)

The motor constant calculator 10 receives the d-axis voltage command value Vdref, the excitation current detection value idfb, and the torque current detection value iqfb as inputs, and calculates the motor winding resistance value Rs and the inductance value Ls according to the invention of claim 1. The output frequency corrector 11 subtracts the same value fcomp from the first output frequency command value f1 so that the output frequency command value f1 is zero when the detected torque current value iqfb is not zero.

ここで、id：励磁電流（一次電流のｄ軸成分）、iq：トルク電流（一次電流のｑ軸成分）、imr：二次界磁電流、Vd：一次電圧のd軸成分、Vq：一次電圧のｑ軸成分、Rs：一次抵抗、Ls：一次自己インダクタンス、σLs：漏れインダクタンス、ω1：回転角速度である。ω1=0、あるいはiq=0に制御し、その定常状態においてimr=idとなる。 Next, the process of the motor constant calculator 10 will be described by taking the case of an induction motor as an example.
First, in the dq control coordinate system that rotates in synchronization with the rotating magnetic field, the current-voltage equation of the induction motor is given by the following equation.

Where id: excitation current (d-axis component of primary current), iq: torque current (q-axis component of primary current), imr: secondary field current, Vd: d-axis component of primary voltage, Vq: primary voltage Q-axis component, Rs: primary resistance, Ls: primary self-inductance, σLs: leakage inductance, ω1: rotational angular velocity. It is controlled to ω1 = 0 or iq = 0, and imr = id in the steady state.

両辺にidを両辺に掛け，両辺を積分すると

ここで、c:積分定数
数式３をRsについて解くと

数式４において、idを固定値あるいは増加の少ない状態にあるとすると右辺第２項第３項は漸近的に減少し、それら最終値はゼロとなる。 Therefore, the first expression of Equation 1 is as follows.

Multiply id on both sides and integrate both sides

Where c: integral constant Equation 3 is solved for Rs

In Equation 4, if id is a fixed value or is in a state of little increase, the second term and the third term on the right side decrease asymptotically, and their final values become zero.

ここで、Δtはサンプリング時間である。
一次抵抗を電流値と電圧値の積を累積加算し、前記累積加算値を電流の二乗値を累積加算した値で除算して演算することによって、大容量の電動機で電圧値が小さくなっても十分な演算精度が得られる。 Accordingly, the primary resistance can be mounted and calculated in the following form.

Here, Δt is a sampling time.
Even if the voltage value decreases with a large-capacity motor, the primary resistance is calculated by accumulating the product of the current value and the voltage value and dividing the accumulated value by the value obtained by accumulating the square value of the current. Sufficient calculation accuracy can be obtained.

ここで、c1:積分定数である。さらに両辺にidを乗算すると

ここで、c2:積分定数である。 Next, an inductance calculation method will be described.
Integrating both sides of Equation 2 gives

Here, c1: an integration constant. If we multiply id on both sides

Here, c2 is an integral constant.

数９の式において、Siがゼロになるように、すなわちidの積分値が周期的にゼロになるように例えば正弦波、矩形波などの指令値を設定し、idを制御すると右辺第２項、３項はゼロとなり、右辺第４項は漸近的に減少し、その最終値はゼロとなる。したがって、インダクタンスは以下の形態で実装演算することができる。

Solving Equation 8 for Ls

In equation (9), a command value such as a sine wave or a rectangular wave is set so that Si is zero, that is, the integrated value of id is periodically zero, and when id is controlled, the second term on the right side The third term becomes zero, the fourth term on the right side decreases asymptotically, and its final value becomes zero. Accordingly, the inductance can be calculated in the following manner.

The Rs and Ls measurement processes described above will be described in a time series with reference to the flowcharts of FIGS.
First, the control device is switched to the Rs measurement mode, and measurement by the motor constant calculator 10 is started (S101). As a measurement condition of Rs, the excitation current command id * is a fixed value (for example, a direct current value) or a gradual change. (S102).
On the other hand, ω1 = 0 and iq = 0 are set. That is, it sets to d-axis measurement (S103). As described above, Equation 5 is derived from Equation 2 (S104). Based on the formula (5), Vd and id are detected for each sampling period Δt (S105). A predetermined number of times Vd and id are detected for each Δt, cumulatively added, and the square value of id is divided by the cumulatively added value to calculate the resistance value Rs (S106).
The obtained calculated value is set in the control device (S107).

Subsequently, the mode is switched to the Ls measurement mode (S108), and as an Ls measurement condition, id * is periodically changed, and a sine wave, a rectangular wave, or the like whose period integration is zero is set as a command value (S109).
Formula 10 is derived from Formula 2 (S110). Based on the equation (10), Vd is detected for each sampling period Δt (S111). A predetermined number of times of Vd detection is performed for each Δt multiple times and cumulative addition is performed, and the product of this and id is divided by a value obtained by cumulatively adding the square value of id to calculate inductance Ls (S112). The obtained inductance Ls is set in the control device (S113).

ここで、φmag:永久磁石による磁束である。
ω1=0、あるいはiq=0に制御している状態では、数１１の第1式は次式のようになる。

したがって、数２の式と数１２の式は同じであることがわかる。すなわち、数５の式と数１０の式は同期電動機にも適用することができる。 The basic principle of the motor constant calculator 10 has been described above by taking the case of an induction motor as an example. Next, the case of a permanent magnet synchronous motor will be described.
Similar to Equation 1, the current voltage equation of the synchronous motor in the dq control coordinate system is given by the following equation.

Here, φmag is a magnetic flux generated by a permanent magnet.
In the state in which ω1 = 0 or iq = 0 is controlled, the first expression of Equation 11 is as follows.

Therefore, it can be seen that the formulas 2 and 12 are the same. That is, the formulas 5 and 10 can be applied to the synchronous motor.

It is a block diagram showing the structure of embodiment of the control apparatus of the alternating current motor in this invention. It is a flowchart of resistance value measurement by the motor constant calculator shown in FIG. It is a flowchart of the inductance measurement by the electric motor constant calculator shown in FIG. It is a block diagram of the variable speed apparatus of a prior art example. It is a figure which shows the characteristic of the electric current and voltage at the time of the constant measurement of the variable speed apparatus shown in FIG. 4 (conventional example). It is a figure which shows the characteristic at the time of the zero electric current at the time of the constant measurement of the variable speed apparatus shown in FIG. 4 (conventional example).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inverter 2 AC motor 3 Current detector 4 Current coordinate conversion circuit 5 Torque current control circuit 6 Excitation current control circuit 7 Phase calculation circuit 8 Output voltage calculation circuit 9 Switching pattern generation circuit 10 Motor constant calculation unit 11 Output frequency corrector

Claims (7)

  In the control arithmetic constant setting method of the control device for controlling the variable voltage and variable frequency with an inverter for the AC motor, the control device includes means for measuring the motor constant of the motor, and the motor constant measurement means is configured to output the motor output frequency or Means for controlling the output torque to zero, and measuring the motor winding resistance value by cumulatively adding the product of the current value and the voltage value, and dividing the cumulative added value by the value obtained by cumulatively adding the square value of the current And means for measuring the inductance value by cumulatively adding the product of the cumulative value of the voltage value and the current value and dividing the cumulative value by the value obtained by cumulatively adding the square value of the current. Control operation constant setting method for AC motor control device.   The control device includes a current detection circuit that detects a current supplied to the AC motor, a coordinate conversion circuit that converts the current supplied to the AC motor into an excitation current detection value and a torque current detection value, and outputs the converted current. An excitation current control circuit that controls the excitation current direction voltage so that the excitation current command value matches the excitation current detection value, and the torque current direction voltage so that the torque current command value matches the torque current detection value A torque current control circuit for controlling the output, a phase angle calculation circuit for calculating a phase angle obtained by integrating a given output frequency command, the excitation current control circuit, and a voltage command output from the torque current control circuit. An output voltage calculation circuit for calculating the magnitude and phase of the output voltage, wherein the output frequency command value or the torque current command value is set to zero, and the output frequency The number or while controlling said torque current to zero, the control calculation constant setting method of an AC motor control apparatus characterized by measuring the motor parameters.   In the control calculation constant setting method, in the measurement method, the motor winding resistance value sets the excitation current command value to a fixed value or a slowly changing value, and the excitation current control circuit and the excitation current command value The method for setting a control operation constant for an AC motor control device according to claim 1, wherein the motor constant is measured in a state in which the excitation current detection value is controlled to coincide with the excitation current detection value.   In the measurement method, the inductance value is set such that the excitation current command value changes periodically and the cycle integral becomes zero, and the excitation current control circuit sets the excitation current command value and the excitation current detection value. 3. The method for setting a control operation constant for an AC motor control device according to claim 2, wherein the motor constant is measured in a state in which control is performed so as to match.   2. The method of setting a control operation constant for an AC motor control device according to claim 1, wherein said motor constant measuring means includes means for automatically controlling said output frequency to zero when said torque current detection value is not zero. .   6. An AC electric motor comprising the control arithmetic constant setting method according to claim 1, wherein a control constant measured by the measuring method or a constant calculated using the control constant is set in a control device. Control device.   When measuring the motor winding resistance value and inductance value, set the output frequency command value and torque current command to zero, set the excitation current command value to a fixed value or a slowly changing value, and set a predetermined sampling period. The product of the detected current value id and the voltage value Vd is cumulatively added, and the cumulative added value is divided by the value obtained by cumulatively adding the square value of the current id to measure the motor winding resistance value. The excitation current command value is periodically changed to a value at which the cycle integral becomes zero, the product of the cumulative addition value of the voltage value Vd and the current value id is cumulatively added, and the cumulative addition value is 7. The control apparatus for an AC motor according to claim 6, further comprising an electric motor constant calculator that measures an inductance value by dividing a square value of the current id by a cumulative addition value.

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