JP2743337B2 - Inverter device with constant measurement setting function - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for driving a three-phase induction motor by an inverter, and more particularly to an inverter device with a constant measurement setting function whose adjustment is simple and highly accurate.

[0002]

2. Description of the Related Art In order to control a three-phase induction motor (hereinafter simply referred to as a motor) with high precision, it is necessary to determine primary and secondary winding resistances, primary and secondary leakage inductances and mutual inductances which are electrical constants of the motor. May be required. The prior art having a function of measuring these electric constants and setting the measured values in the inverter is shown in FIG.

FIG. 2 shows the configuration of a main part of a conventional example, wherein 1 is an inverter, 2 is a motor, 3 is a current detector, 4
Is a voltage detector. Also, 51 is a magnetic flux torque control means,
6 is a no-load test means, 7 is a DC test means, 8 is a single-phase test means, 91 is a constant calculation means, 101 is a selector, and 111 is a setting storage means. In FIG. 2, the inverter 1 is a selector.
A switching signal of 101 output is input and operated according to the switching signal, and a voltage can be applied to the electric motor 2 by the inverter 1.

First, the motor 2 is set to no load, and the selector 101
Selects the switching signal output from the no-load test means 6 and outputs it to the inverter 1. The motor 2 rotates at a high speed, and the no-load test means 6 inputs the input current and the input voltage of the motor 2 from the current detector 3 and the voltage detector 4 to obtain the magnitude and phase of the fundamental wave. The primary self-inductance L1 of the electric motor 2 is obtained from the relationship, and is output to the constant calculating means 91.

Next, the selector 101 selects the switching signal output from the DC test means 7 and outputs it to the inverter 1. When the motor 2 is stopped, a DC voltage is applied between two of the three-phase input terminals, and the DC test means 7
The current and the voltage detected by the current detector 3 and the voltage detector 4 are input, the primary winding resistance R1 is obtained from the ratio thereof, and the primary resistance R1 is output to the constant calculating means 91. Finally, the selector 101 selects the switching signal output from the single-phase test means 8 and outputs it to the inverter 1. With the motor 2 stopped, a single-phase AC voltage is applied between two of the three-phase input terminals, and the single-phase test means 8 detects the current and voltage detected by the current detector 3 and the voltage detector 4. The magnitudes and phases of the fundamental waves are inputted to obtain the sum of the primary and secondary leakage inductances (L01 + L02) and the sum of the primary and secondary winding resistances (R1 + R2) from the relationship. Constant calculation means 91
Output to

The constant calculating means 91 includes no-load test means 6 and
The outputs of the DC test means 7 and the single-phase test means 8 are input,
Assuming that the primary leakage inductance and the secondary leakage inductance are equal, the leakage inductance L, the mutual inductance M, the primary winding resistance R1 and the secondary winding resistance R2 are obtained and output to the setting storage means 111. The setting storage unit 111 sets and stores the input electrical constant of the output of the constant calculation unit 91 in the memory of the inverter. The magnetic flux torque control means 51 includes:
A switching signal for controlling the magnetic flux and torque of the electric motor 2 is output to the inverter 1 via the selector 101 based on the electric constants set and stored in the setting storage unit 111.

[0007]

In the torque control of the electric motor, the electric torque can be controlled with high accuracy if the electric constant of the electric motor can be accurately grasped. However, the required torque is the shaft torque of the motor rotor,
It is reduced by the mechanical loss consumed by the rotation of the rotor. Thus, the shaft torque cannot be controlled with high accuracy.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points. First, there are provided two non-load test means having a constant frequency and different voltage, and In the constant calculation means, determine the input power excluding the iron loss and the power consumed in the primary winding based on the magnitude and phase of the voltage and current detected by each no-load test means, and calculate the mechanical loss as the difference between them. Thirdly, the configuration is such that the mechanical loss of the electric motor is set and stored in the memory of the inverter by the setting storage means, and the torque for the mechanical loss is corrected when the torque of the electric motor is controlled by the inverter.

[0009]

In order to correct the decrease in the shaft torque due to the mechanical loss of the rotor of the electric motor, it is sufficient to understand the mechanical loss, which can be achieved by the above solution. That is, the input power P in the no-load test of the motor is divided into copper loss PC, iron loss PI, and mechanical loss PM consumed in the primary winding. Therefore, the copper loss PC and the iron loss PI may be determined to determine the mechanical loss PM. Now, the copper loss PC is the primary winding resistance R1
Is obtained by the DC test means of the prior art, and is obtained by the following equation (1). Here, I is the effective value of the input current during the no-load test.

PC = 3 × I (square) × R1 (1)

Next, the iron loss PI can use two no-load test means. The iron loss PI is proportional to the square of the voltage if the frequency is the same. The operation is performed twice with different voltages. Assuming that the mechanical loss at that time is constant, it can be obtained by equation (2). Here, P2, PC2, and V2 are input power, copper loss, and voltage in the second no-load test, respectively. Therefore,
From the copper loss PC and iron loss PI thus obtained, the mechanical loss PM
Is obtained by the following equation (3).

PI = V (square) × [(P-PC) (P2
-PC2)] / [V (square) -V2 (square)] ...
... (2) PM = P-PC-PI ...
・ (3)

Further, the obtained mechanical loss is set and stored in the memory of the inverter by the setting storage means, and when the shaft torque of the electric motor is controlled by the inverter, the torque command or the like is corrected by the amount corresponding to the mechanical loss. Thus, a desired shaft torque can be obtained. Hereinafter, the present invention will be described in more detail with reference to the drawings.

[0014]

FIG. 1 shows an embodiment according to the present invention shown in FIG. 2, wherein 52 is a magnetic flux torque control means, 61 and 62 are no-load test means, 92 is a constant calculation means, and 102 is a constant calculation means. Selector, 1
Reference numeral 12 denotes a setting storage unit. That is, assuming that FIG. 1 is performed in the same order as the description in FIG.
02 The switching signal of the output is input and operated according to the switching signal.
Can be applied with a voltage.

First, the motor 2 is set to no load, and the selector 102 is turned off.
Selects the switching signal output from the no-load test means 61 and outputs it to the inverter 1. The motor 2 rotates at a high speed, and the no-load test means 61 inputs the input current and the input voltage of the motor 2 from the current detector 3 and the voltage detector 4 to obtain the magnitude and phase of the fundamental wave thereof. The primary self-inductance L1 of the electric motor 2 is obtained from the relationship, and is output to the constant calculating means 92. Also, input power P, input current I, input voltage V
Is also output to the constant calculation means 92.

Similarly, the selector 102 selects the switching signal output from the no-load test means 62 and outputs it to the inverter 1. At this time, the voltage is different from that of the no-load test means 61 at the same frequency. The no-load test means 62 receives the input current I2 and the input voltage V2 of the electric motor 2 from the current detector 3 and the voltage detector 4, obtains the input power P2, and outputs it to the constant calculation means 92.

Next, the selector 102 selects the switching signal output from the DC test means 7 and outputs it to the inverter 1. When the motor 2 is stopped, a DC voltage is applied between two of the three-phase input terminals, and the DC test means 7
The current and the voltage detected by the current detector 3 and the voltage detector 4 are input, the primary winding resistance R1 is obtained from the ratio thereof, and output to the constant calculation means 92.

Next, the selector 102 is connected to the single-phase test means 8.
An output switching signal is selected and output to the inverter 1. With the motor 2 stopped, a single-phase AC voltage is applied between two of the three-phase input terminals, and the single-phase test means 8 detects the current and voltage detected by the current detector 3 and the voltage detector 4. Then, the magnitudes and phases of the fundamental waves are obtained, and the sum of the primary and secondary leakage inductances (L011 + L021) and the sum of the primary and secondary winding resistances (R11 + R21) are obtained from the relationship. Output to the constant calculation means 92.

The constant calculation means 92 includes a no-load test means 61, a no-load test means 62, a DC test means 7, and a single-phase test means 8.
Input the output of The constant calculation means 92 calculates the respective copper losses PC and PC2 using the equation (1) from the currents I and I2 of the outputs from the no-load test means 61 and 62 and the primary winding resistance R1 output from the DC test means 7, The iron loss PI is obtained from the equation (2), and the mechanical loss PM is obtained from the equation (3). Here, assuming that the primary and secondary leakage inductances are equal, a half of the sum of the leakage inductances of the outputs of the single-phase test means is defined as a leakage inductance L. Further, the mutual inductance M is defined as (M = L1-
L). In this way, the constant calculation means 92 outputs the electrical constants L, M, R1, R2, PM to the setting storage means 112.

In the setting storage procedure 112, the input electric constants are set and stored in the memory of the inverter. The magnetic flux torque control means 52 outputs a switching signal for controlling the magnetic flux and the tort of the electric motor 2 to the inverter 1 via the selector 102 based on the electric constants set and stored in the setting storage means 112. At this time, of course, control for compensating for the mechanical loss PM is performed.

[0021]

As described above, according to the present invention, a high-precision control in which the mechanical loss due to the rotation of the motor rotor is measured and set and stored in the memory of the inverter, and the mechanical loss is corrected in the torque control of the motor. Can be provided with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a main part of an embodiment according to the present invention.

FIG. 2 is a block diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inverter 2 Three-phase induction motor (motor) 3 Current detector 4 Voltage detector 51 Magnetic flux torque control means 52 Magnetic flux torque control means 6 No-load test means 61 No-load test means 62 No-load test means 7 DC test means 8 Single phase Test means 91 Constant calculation means 92 Constant calculation means 101 Selector 102 Selector 111 Setting storage means 112 Setting storage means L Leakage inductance M Mutual inductance R1 Primary winding resistance R2 Secondary winding resistance PM Mechanical loss

Claims (1)

(57) [Claims] 1. An inverter for supplying power to a three-phase induction motor, comprising: applying a three-phase AC voltage to a motor in a no-load state to detect the magnitude and phase of an input voltage and an input current of the motor; No-load test means for measuring self-inductance, DC test means for applying a DC voltage to the three-phase induction motor to detect the magnitude of the input voltage and input current of the motor and measure the primary winding resistance of the motor, A single-phase AC voltage is applied to a phase induction motor to detect the magnitude and phase of the input voltage and input current of the motor, and to measure the sum of the primary and secondary leakage inductances and the sum of the primary and secondary winding resistances of the motor. A single-phase test means, a constant calculating means for calculating a leakage inductance and a mutual inductance, a primary winding resistance and a secondary winding resistance, which are electric constants of the motor from the output of each of the test means, and the electric constant In the inverter device with a constant measurement setting function consisting of setting storage means for storing in a memory of the inverter, two constant no-load test means having a constant frequency and different voltage, Based on the magnitude and phase of the detected voltage and current, calculate the input power excluding iron loss and power consumed by the primary winding, and calculate the mechanical loss as the difference between them, and set the mechanical loss of the motor in the inverter memory. An inverter device with a function of measuring and setting constants, wherein the inverter device memorizes and corrects a mechanical loss torque of an electric motor.