JP2001286197A - Speed detection abnormality judgment circuit of vector controlling equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely detect a speed detection abnormality whether it is in a high-speed range or in a low speed range. SOLUTION: To vector-control an induction motor 2 a speed detection value ωr is calculated with a pulse signal P of a speed detection sensor (a pulse pickup). In a speed detection abnormality judgment circuit 100 effective power W which removes the influence of primary resistor and a leakage inductance of the induction motor 2 is calculated with a d-axis voltage instruction Vd* and a q-axis voltage instruction Vq* and a d-axis detection current Id and a q-axis detection current Iq. When the symbol of the effective power W and that of a q-axis current instruction (a torque component current instruction) Iq* do not agree and the speed detection value ωr is zero, it is judged as a detected speed abnormality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed detection abnormality judging circuit of a vector control device, and relates to a speed control using a pulse pickup type speed detection sensor to perform vector control in order to perform variable speed control of an induction motor. This is a technique for determining that the motor rotation speed cannot be obtained due to an abnormality in the speed detection mechanism.

[0002]

2. Description of the Related Art Based on a pulse signal output from a speed detection sensor directly connected to a rotor of an induction motor, a speed detection unit calculates a speed detection value indicating the rotation speed of the induction motor,
In the case of performing vector control of the induction motor so that the speed detection value becomes equal to the speed command, when an abnormality occurs in the speed detection mechanism including the speed detection sensor and the speed detection unit,
Since operation cannot be continued as it is, it is necessary to display a failure or switch to another control (for example, constant V / F control). Therefore, it is necessary to detect that the speed detection mechanism is abnormal.

[0003] At present, it is considered that a speed detection abnormality is detected when the change value of the speed detection value exceeds a preset threshold value and the speed detection value becomes zero.

Here, a general example of a vector control device that performs vector control using a speed detection sensor will be described with reference to FIG.

As shown in FIG. 6, the induction motor 2 rotates by supplying three-phase power from the PWM inverter 1 to the induction motor 2. The speed detection sensor 3, which is a pulse pickup type encoder, is directly connected to the rotor of the induction motor 2 and is rotated, and outputs a pulse signal P according to the rotation speed. Speed detecting unit 4 receives the pulse signal P, and outputs the speed detection value omega _r indicating the rotational speed of the induction motor 2.

[0006] The current detection unit 5 includes three-phase detection currents I _u, I _v, indicating three-phase current values sent from the inverter 1 to the induction motor 2 _.
Detecting the I _w, the three-phase detected currents I _u, seek I _v, d-axis detected current from I _w I _d and the q-axis detection current I _q.

The speed control unit 6 calculates a q-axis current command (current command for torque) I _q ^* by performing a proportional / integral calculation on a deviation between the speed command ω _r ^* and the detected speed value ω _r .

[0008] The current control unit 7 includes a d-axis current command I _d ^* and d
A deviation from the axis detection current _Id is calculated by a proportional / integral calculation to obtain a d-axis voltage command _Vd ^* . The current control unit 8 controls the q-axis current command I
The deviation between _q ^* and the q-axis detection current _Iq is calculated in proportion and integral to obtain a q-axis voltage command _Vq ^* .

The two-phase / three-phase converter 9 outputs a d-axis voltage command V _d ^*
And q-axis voltage command V _q ^* are converted into two-phase and three-phase to output three-phase voltage commands v _u , v _v, v _w . The inverter 1 is controlled based on the three-phase voltage commands v _u , v _v, v _w to supply a three-phase voltage to the induction motor 2.

[0010]

As described above, the speed detecting section 4 measures the pulse interval time of the pulse signal P output from the speed detecting sensor 3 to obtain the speed detection value ω.
have got _r . As a cause of a failure in such a detection mechanism (a mechanism for speed detection including the speed detection unit 4 and the speed detection sensor 3), a disconnection of a signal line, a failure of the speed detection unit 4, a failure of the speed detection sensor 3, and the like can be considered. . When such a failure occurs, it becomes impossible to detect the pulse signal P, the speed detection value omega _r is zero at the time of speed detection abnormality.

[0011] Therefore, when driving at a certain rotational speed, the resulting speed detection abnormality, the speed detection value omega _r is becomes zero from a certain rotational speed instantaneously. Therefore, if the case were the speed change over the speed variation due to normal deceleration or load fluctuations, and became the speed detection value omega _r substantially zero can be considered as has brought the abnormal speed detection mechanism .

In such a speed detection abnormality judging method, the threshold value for judgment must be increased when the normal acceleration / deceleration operation or load fluctuation is steep. There is a problem that judgment cannot be made.

The present invention has been made in view of the above-mentioned prior art, and has as its object to provide a vector control device having a novel method capable of reliably detecting a speed detection abnormality not only in a high speed region but also in a low speed region. And

[0014]

According to a first aspect of the present invention, a speed detection value is obtained based on a pulse signal output from a speed detection sensor directly connected to a rotor of an induction motor. A speed detection abnormality determination circuit provided in a vector control device that vector-controls an induction motor so that a value becomes equal to a speed command, the d-axis voltage command and the q-axis voltage command, and the d-axis detection current and the q-axis detection current. Is calculated based on the effective power obtained by removing the effects of the primary resistance and the leakage inductance of the induction motor, and the sign of the effective power does not match the sign of the q-axis current command, and the speed detection value is zero. It is characterized in that it is determined that the speed detection is abnormal when.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. Since the basic configuration of the vector control mechanism is the same as that shown in FIG. 6, the same parts as those of the prior art are denoted by the same reference numerals, and the description of the duplicated parts is omitted. Will be described.

First, the basic principle of the present invention will be described. The current and voltage in the steady state of the induction motor 2 are related by the TI equivalent circuit shown in FIG. In FIG. 1, I ₁ is a primary current, I ₀ is an exciting current,
It is the torque current, V ₁ is the motor terminal voltage, E ₁ is the primary induced voltage, E ₂ is the secondary induced voltage, R ₁ is the primary resistance, L
s is the leakage inductance, M 'is the mutual inductance,
R ₂ ′ is a secondary resistance and s is a slip.

Primary resistance R ₁ and leakage inductance Ls
The impact of the removal of the relationship of the secondary induced voltage a voltage vector and the current vector of the primary current I ₁ of the E ₂ is as shown in FIG.

As shown in FIG. 2, during normal operation, the sign of the torque command (q-axis current command _Iq ^* = current command for torque) and active power (excluding the influence of primary resistance and leakage inductance. The same).

On the other hand, the speed detection abnormality occurs, and the speed command and the motor speed are the operating speeds.
The voltage vector and current vector when only the speed detection value omega _r is zero is shown in FIG.

As shown in FIG. 3, when a speed detection abnormality occurs, the speed command ω _r ^* is positive (during normal rotation) and the speed detection value ω _r is zero, so the torque command (q-axis current command _Iq ^* = torque current command) becomes positive. Further, since the output frequency is given by the speed detection value + slip frequency, the output frequency becomes a small positive slip frequency and substantially regenerates, and the voltage vector is determined by the current controller (AC
R) automatically moves to a regenerative position. Therefore, the sign of the torque command and the sign of the active power are different. The same applies to the case of reverse rotation.

As described above, the sign of the torque command (that is, the sign of the q-axis current command Iq ^* , which is the torque component current command) and the sign of the active power (one that eliminates the influence of the primary resistance and the leakage inductance) are monitored. Are different and the speed detection signal is zero, it can be determined that the speed detection is abnormal.

<First Embodiment> FIG. 4 shows a speed detection abnormality judging circuit 100 of a vector control device according to a first embodiment based on the above findings. The speed detection abnormality determining circuit 100, a d-axis voltage command V _d ^* and the q-axis voltage command V _q ^*, the d-axis detected current I _d and the q-axis detection current I _q and the velocity detection value omega _r is captured .

For the d-axis voltage command V _d ^* , the subtraction unit 1
01, [I _d × R ₁ ] is subtracted, and [I _q × ωLs] is added in the adder 102 to remove the influence of the primary resistance R ₁ and the leakage inductance Ls. E ₂ d is obtained. Note that 103 and 104 are R ₁ , ωLs
Is a multiplier for multiplying by.

For the q-axis voltage command V _q ^* , a subtraction unit 1
At step 05, [I _q × R ₁ ] is subtracted, and at the subtracting section 106, [I _d × ωLs] is added to remove the influence of the primary resistance R ₁ and the leakage inductance Ls. E ₂ q is obtained. Note that 107 and 108 are R ₁ , ωLs
Is a multiplier for multiplying by.

The active power calculator 109 takes in the d-axis secondary induced voltage E ₂ d and the q-axis secondary induced voltage E ₂ q, the d-axis detection current I _d and the q-axis detection current I _q, and obtains the primary resistance R Calculate the active power W excluding the influence of ₁ and the leakage inductance Ls. The active power W is calculated based on the following equation. W = (E ₂ d × I _d ) + (E ₂ q × I _q )

The speed detection abnormality judging section 110 determines whether or not the torque
Q-axis current command I which is a flow command_q ^*And active power W and speed detection
Outgoing price ω_rTake in. Then, the speed detection abnormality determination unit 11
0 is the q-axis current command I_q ^*And the sign of the active power W
Different and speed detection value ω _rIs zero when
It is determined that the degree is abnormal.

<Second Embodiment> FIG. 5 shows the first embodiment.
A speed detection abnormality determination circuit 110 according to the embodiment;
This is a combination of the conventional speed detection abnormality determination circuit 120.

[0028] In the speed detecting abnormality judging circuit 120, and the previous speed detection value omega _r delayed by delay circuit 121, the deviation between the current detected speed omega _r (speed change value) subtractor 122
Ask at. The threshold determination unit 123 calculates deviation (velocity change value) is greater than a predetermined threshold value, and determines that the current speed detection value omega _r is If becomes zero, the speed detection error.

When it is determined that at least one of the speed detection abnormality determination circuits 100 and 120 is abnormal, the determination result output section 130 finally outputs to the outside that the speed detection abnormality is abnormal.

In the second embodiment, the speed detection abnormality is determined by the speed detection abnormality determination circuit 120 during high-speed operation, and the speed detection abnormality is determined by the speed detection abnormality determination circuit 100 during low-speed operation. At the same time, the torque fluctuation at the time of abnormal speed detection is suppressed as much as possible, and at the same time, the abnormality can be determined even at low speed.

[0031]

As described above, according to the present invention, when the sign of the active power does not match the sign of the q-axis current command and the speed detection value is zero, it is determined that the speed detection is abnormal. With this configuration, the speed detection abnormality can be reliably detected not only in the high-speed range but also in the low-speed range.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a TI equivalent circuit of an induction motor.

FIG. 2 is a vector diagram showing a relationship between a voltage vector and a current vector in a normal state.

FIG. 3 is a vector diagram showing a relationship between a voltage vector and a current vector when speed detection is abnormal.

FIG. 4 is a circuit diagram showing a first embodiment of the present invention.

FIG. 5 is a circuit diagram showing a second embodiment of the present invention.

FIG. 6 is a circuit diagram showing a general example of a vector control device.

[Description of Signs] 1 PWM inverter 2 Induction motor 3 Speed detection sensor (pulse pickup) 4 Speed detection unit 5 Current detection unit 6 Speed control unit 7, 8 Current control unit 9 Two-phase three-phase conversion unit 100 Speed detection abnormality determination unit 120 Speed detection abnormality judgment unit

Claims (1)

[Claims] 1. A speed detection value is obtained based on a pulse signal output from a speed detection sensor directly connected to a rotor of an induction motor, and the speed detection value is equal to a speed command.
A speed detection abnormality determination circuit provided in a vector control device that vector-controls an induction motor, comprising: a d-axis voltage command and a q-axis voltage command; a d-axis detection current and q
Based on the axis detection current, an active power is calculated by removing the influence of the primary resistance and the leakage inductance of the induction motor, and the sign of the active power does not match the sign of the q-axis current command, and the speed detection is performed. A speed detection abnormality determining circuit that determines that the speed detection is abnormal when the value is zero.