JP2850096B2 - Inverter control method 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 an inverter control method with a constant measurement setting function for driving an electric motor by an inverter, which has advanced the measurement of electric constants.

[0002]

2. Description of the Related Art When driving a polyphase induction motor with a polyphase inverter, a polyphase induction motor (hereinafter simply referred to as a motor) is used.
In order to control with high accuracy, the values of the primary and secondary winding resistance, the primary and secondary leakage inductance, and the mutual inductance, which are the electrical constants of the motor, may be required. Conventional technology having a function of measuring these electrical constants and setting them in a polyphase inverter (hereinafter simply referred to as an inverter)
It was as shown in FIG.

FIG. 2 shows a system configuration of a main part of a conventional inverter device having a constant measurement setting function, wherein 1 is an inverter, 2 is a motor, 3 is a current detector, and 4 is a voltage detector. Further, 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 receives a switching signal output from the selector 101, is operated according to the switching signal, and can apply a voltage to the electric motor 2 by the inverter 1.

First, the motor 2 is set to no load and the selector 1
01 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. Motor 2 from the relationship
The primary self-inductance L1 is calculated to obtain a constant calculating means 91.
Output to

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.

[0006] 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,
Is obtained by inputting the current and voltage detected by the current detector 3 and the voltage detector 4, obtaining the magnitude and phase of the fundamental wave, and calculating the sum of the primary and secondary leakage inductances (L01 + L02) from the relationship therebetween. , The sum of the primary and secondary winding resistances (R
1 + R2) and outputs it to the constant calculation means 91.

In the constant calculating means 91, the no-load test means 6,
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.

[0008]

In the case of a squirrel-cage induction motor, the values of the secondary winding resistance and the secondary leakage inductance change with the frequency of the current flowing through the secondary conductor due to the skin effect. The single-phase test means 8 shown in the prior art applies an AC voltage of one frequency to the electric motor 2 and sums the primary and secondary leakage inductances (L01 + L02) and the primary and secondary winding resistances ( R1 + R2). Since the measured value is the value at the frequency of the applied AC voltage and is different from the value at the secondary frequency in normal operation, the leakage inductance and secondary winding measured by such single-phase test means The resistance is not the required value in normal operation.

Therefore, a single-phase test may be performed at the secondary frequency in normal operation. However, since the frequency is extremely low, the voltage applied to the motor is low, and the voltage detection accuracy is poor and the constant measurement accuracy is low. As a result, the control performance in the normal operation for controlling the torque and the magnetic flux deteriorates. In addition, finding the constant at the secondary frequency by a calculation formula requires a lot of trouble. An object of the present invention is to provide a control method capable of realizing an inverter device having a highly accurate constant measurement setting function in which electrical constants are advanced.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and a single-phase test is performed under n conditions having different frequencies, and a secondary winding under each test condition is performed. An mth-order (m ≦ n−1) polynomial with the test frequency as a variable is derived for the line resistance and the leakage inductance, and the secondary winding resistance and the leakage inductance used in the control system are obtained from the zero-order component of the polynomial. It is what was constituted.

[0011]

According to this solution, the secondary winding resistance and the leakage inductance can be obtained from the zero-order component of the polynomial, thereby eliminating the measurement error of the single-phase test due to the skin effect, and reducing the secondary frequency in normal operation. The secondary winding resistance and the leakage inductance close to the above values can be set and stored in the inverter by a simple constant calculating means, so that the control performance such as the torque in the normal operation can be improved. Hereinafter, the present invention will be described in more detail with reference to the drawings.

[0012]

FIG. 1 shows an embodiment to which the present invention shown in FIG. 2 is applied.
1, 8n are single-phase test means, 92 is constant calculation means, 102 is a selector, and 112 is setting storage means. That is, assuming that FIG. 1 is performed in the same order as that of FIG. 2, the inverter 1 receives a switching signal output from the selector 102, is operated according to the switching signal, and applies a voltage to the electric motor 2 by the inverter 1. be able to.

First, the motor 2 is set to no load, and the selector 1
02 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. Motor 2 from the relationship
The primary self-inductance L1 is calculated to obtain a constant calculating means 92.
Output to

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 sequentially selects the switching signals output from the plurality of single-phase testing means 81 to 8n and outputs the switching signals to the inverter 1. With the motor 2 stopped, a single-phase AC voltage is applied between two of the three-phase input terminals. Here, it is assumed that the frequency of the voltage applied to the motor is different among the n single-phase test means. Each of the single-phase test means 81 to 8n receives the current and voltage detected by the current detector 3 and the voltage detector 4 to determine the magnitude and phase of the fundamental wave, and from the relationship, the primary and secondary Sum of leakage inductance (L011 +
L021) to (L01n + L02n) and the sum of primary and secondary winding resistances (R11 + R21) to (R1n + R2n),
Constant calculating means together with the frequency of the voltage (F1 to Fn)
Output to 92.

The constant calculation means 92 inputs the outputs of the no-load test 6, the DC test means 7, and the n single-phase test means 81, 8n. Here, it is assumed that the primary leakage inductance and the secondary leakage inductance are equal, and half of the sum of the leakage inductances of the outputs of the respective single-phase test means is defined as the leakage inductance (L1 to Ln) of the respective single-phase test means.

Further, the frequency change characteristic of the leakage inductance is calculated by using the frequency of the applied voltage as a variable (m ≦ n−1).
Equation (1) is defined as an m-th order polynomial satisfying the following equation. L · F = A · F (power m) + B · F (power m−1) + ── + Z −−− (1)

Here, the frequency (F1 to Fn) is calculated by the equation (1).
Leakage inductance (L1 to Ln) measured at
And the coefficients A, B, and Z can be obtained by the undetermined coefficient method. Then, since the value of the frequency 0 Hz is adopted, only the zero-order component Z needs to be calculated, and the calculation is very simple. The estimated true value of the leakage inductance of the zero-order component Z of the m-th order polynomial is L. Similarly, the frequency (F1 to Fn)
Using the secondary winding resistance (R21 + R2n) measured in the above, the zero-order component of the m-th order polynomial is defined as the estimated true value of the secondary winding resistance as R2. Further, the mutual inductance (M = L1
-L), and as electrical constants, L, M, R1, R2
Is output 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 torque 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.

[0020]

As described above, according to the present invention, the measurement error of the secondary winding resistance and the leakage inductance due to the skin effect of the motor secondary conductor is eliminated, and the secondary winding near the value at the secondary frequency in normal operation is eliminated. It is possible to provide a special control method that can realize a device that performs high-precision motor control by obtaining the secondary winding resistance and the leakage inductance.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main system configuration of an embodiment to which the present invention is applied.

FIG. 2 is a block diagram showing a main part system configuration of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polyphase inverter (inverter) 2 Polyphase 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 7 DC test means 8 Single phase test means 81 Single phase Test means 8n 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

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H02P 21/00 H02P 5/408-5/412 H02P 7/628-7/632

Claims (1)

(57) [Claims] 1. A multi-phase inverter supplies a test power supply such as a single-phase or a direct-current (DC) to measure an electric constant of a multi-phase induction motor, and automatically sets a result of the measurement as a parameter for drive control to configure a control system. In the inverter control method with the constant measurement setting function to be configured, the single-phase test is performed for n
The m-th order (m ≦ n−1) polynomial with the test frequency as a variable is derived for the secondary winding resistance and the leakage inductance under each test condition, and the zero order of the polynomial is performed. An inverter control method with a constant measurement setting function, wherein values of a secondary winding resistance and a leakage inductance used in the control system are obtained from the values.