JP4993889B2 - Induction machine controller - Google Patents

Description

  The present invention relates to induction machine control, and in particular, detects that induction machine current information has been lost.

FIG. 3 is a block diagram showing a conventional example. Reference numeral 1 denotes an induction machine, 2 denotes a current detector, 3 denotes a power converter, 4 denotes current control means, 5 denotes control command creation means, and 6 denotes an adder.
The current detector 2 detects a current i flowing through the induction machine 1.

  The control command creating means 5 outputs a torque control current command I1 * and a slip command ωs * from the magnetic flux command φ * and the torque command τ *.

For example, the torque control current command I1 * is represented by a vector of the flux component current command IdP and the torque component current IqP, and IdP, IqP, and ωs * are created by Equations (1) to (3).
IdP = φ * / M formula (1)
IqP = τ * / φ * Equation (2)
ωs * = R2 / L2 • IqP / IdP equation (3)

  The adder 6 takes the sum of the slip command ωs * and the induction machine speed ωm and sets it as the torque control frequency command ω11 *.

Based on the torque control frequency command ω11 *, the torque control current command I1 *, and the induction machine current i, the current control means 4 is a voltage at which the magnetic flux and torque of the induction machine 1 become the magnetic flux command φ * and the torque command τ *. Command v is output.
The power converter 3 amplifies the voltage command v and supplies power to the induction machine 1.

With the above configuration, the torque of the induction machine 1 can be controlled to the torque command τ *.
JP 11-069895 None

The prior art has the following problems.
When carrying out control of the induction machine 1 using the current control means 4, when the current information of the induction machine is lost due to the failure of the current detector 2 or the power failure of the current detector 2, the current control means The voltage command v by 4 becomes excessive, which may cause element destruction of the power converter 3 and heat destruction of the induction machine 1. In particular, when the induction machine speed ωm is low, the possibility of element destruction of the power converter 3 and thermal destruction of the induction machine 1 becomes very high.

At first glance, it seems that it is possible to detect that the induction machine current information is lost because the voltage command v is excessive, but this is not possible for the following reason.
When the induction machine speed ωm is low, the increase rate of the induction machine current is very high, and there is a possibility that the element destruction of the power converter 3 and the thermal destruction of the induction machine 1 are caused before detection.
-When the induction machine speed ωm is high, the voltage command v becomes large, so that it cannot be determined as excessive.
The present invention has been made to solve the above problems.

In order to solve the above problems, the following configuration is adopted.
In claim 1,
Switching command creation means 7 for inputting the operation flag ST and outputting the switching flag CH,
Test command creation means 8 for outputting test current command I2 * and test frequency command ω12 *,
A switching means 9 for inputting a torque control current command I1 *, a torque control frequency command ω11 *, a test current command I2 *, a test frequency command ω12 *, and a switching flag CH, and outputting a switching current command I * and a switching frequency command ω1 *;
Protection detection means 10 for inputting a voltage command v and a switching flag CH and outputting a protection occurrence flag DT;
And a switching current command I * and a switching frequency command ω1 * are input to the current control means 4 instead of the torque control current command I1 * and the torque control frequency command ω11 *.

A protection occurrence flag DT is newly input to the current control means 4.

In claim 2 ,
A forward / reverse rotation flag FR and a frequency set value ω1set are newly input to the test command creating means 8.

In claim 1 ,
The voltage setting value Vset is input to the test command creation means 8 and the protection detection means 10.

The switching command creation means 7 is configured to turn on the switching flag CH for a certain time after the operation flag ST is turned on.

  With the above configuration, if the test current command I2 * and the test frequency command ω12 * are selected in consideration of the motor constant of the induction machine 1, the induction machine current will increase even if the voltage command v is excessive. There is no. In addition, it is possible to detect that the induction machine current information has been lost due to a failure of the current detector 2, a power failure of the current detector 2, etc., and the control of the induction machine 1 can be canceled. Further, with the configuration shown in claim 5, it is possible to detect that the induction machine current has been lost before the torque control of the induction machine 1 is started.

  Before starting the torque control of the induction machine 1, the test current command I2 * and the test frequency command ω12 * are selected in consideration of the motor constant of the induction machine 1, and the validity of the voltage command v as a result of the current control means 4 is selected. The induction machine current loss is detected, and the control of the induction machine 1 is canceled.

  FIG. 1 is a block diagram showing an embodiment of the present invention, in which 7 is a switching command creating means, 8 is a test command creating means, 9 is a switching means, and 10 is a protection detecting means.

The switching command creation means 7 inputs the operation flag ST and outputs a switching flag CH.
The test command creating means 8 outputs a test current command I2 * and a test frequency command ω12 *. The test current command I2 * and the test frequency command ω12 * are constant values determined in consideration of the motor constant of the induction machine 1.

  The test frequency command ω12 * sets a considerably high frequency. Two times the maximum operating frequency of the induction machine 1 is necessary. The reason will be described with reference to FIG. If the primary frequency of the induction machine 1 is large, the impedances of the leakage inductances l1 and l2 are increased, and W1 / WS is also reduced to about 1-2, so that the resistance components R1 and R2 are equivalent to a short circuit. Further, since the impedance of the M portion is high, the M portion is equivalent to an open state. As a result, the equivalent circuit of the induction machine 1 has only a high-impedance leakage inductance component, and even if an excessive voltage is input, the induction machine current is unlikely to be excessive.

  The test current command I2 * is set to a value less than half the current that flows when the maximum voltage is input to the equivalent circuit on the right side of FIG. As a result, processing in the protection detection means 10 described later can be simplified.

  The switching means 9 inputs a torque control current command I1 *, a torque control frequency command ω11 *, a test current command I2 *, a test frequency command ω12 *, and a switching flag CH, and outputs a switching current command I * and a switching frequency command ω1 *. Output. One of (I1 *, ω11 *) and (I2 *, ω12 *) is selected by the switching flag CH, and is output as a switching current command I * and a switching frequency command ω1 *.

The protection detection means 10 receives the voltage command v and the switching flag CH, and outputs a protection occurrence flag DT. When (I2 *, ω12 *) is selected by the switching flag CH, if the current detector 2 is normal and the induction machine current i is appropriate, the voltage command v becomes a value according to the right side of FIG. Conversely, if the current detector 2 is abnormal and the induction machine current i is 0, a voltage command v that is larger than the appropriate value is input. Therefore, the protection occurrence flag DT can be created according to the magnitude of the voltage command v.
If the set test current command I2 * is too large, the voltage command v when the current detector 2 is normal / abnormal will have almost the same value, so I2 * as shown in [0020] is appropriate.

  With the above configuration, in addition to the torque control portion of the induction machine 1, a portion for detecting an abnormality in the current detector 2 is configured, the current detector 2 has failed, the power supply to the current detector 2 is cut off, etc. For this reason, it is possible to detect that the induction machine current information has been lost.

  By inputting the protection occurrence flag DT output by the protection detection means 10 to the current control means 4, when it is detected that the induction machine current information is lost, the voltage command v is set to 0 and the control of the induction machine 1 is canceled. be able to.

In the test command creation means 8, the forward / reverse rotation flag FR and the frequency set value ω1set are newly input, and the test frequency command ω12 * is created by the following equations (8) and (9).
ω12 * = −ω1set @FR forward rotation formula (8)
ω12 * = ω1set @FR reversal formula (9)
In an electric vehicle, generally, the direction of rotation of the induction machine 1 corresponds to the forward / reverse rotation flag FR. At this time, if Expressions (8) and (9) are used, the magnitude of W1 / WS is always smaller than 1 regardless of the frequency setting value ω1set and the induction machine speed ωm. As a result, the influence of the R2 portion in FIG. 2 is reduced. This indicates that the frequency set value ω1set can be fixed regardless of the characteristics of the induction machine 1.

The voltage setting value Vset is newly input to the test command creating means 8, and the test current command I2 * is created by the equation (10).
I2 = Vset / ω12 * / (l1 + l2)
, I2 * = (I2, 0) Equation (10)
Thus, if the current detector 2 is normal, the magnitude of the voltage command v substantially matches the voltage setting value Vset.
Further, the protection detection means 10 can be newly input with the voltage set value Vset, and the protection occurrence flag DT can be created by comparison with the magnitude of the voltage command v.

  The switching command creating means 7 is configured to turn on the switching flag CH for a predetermined time after the operation flag ST is turned on. Thereby, before the torque control of the induction machine 1 is started, the test current command I2 * and the test frequency command ω12 * are given to the induction machine 1, and it can be determined by the protection generation flag DT whether the induction machine current information is lost.

  It becomes possible to detect that the current information of the induction machine has been lost due to the failure of the current detector 2 or the power failure of the current detector 2, etc., thereby preventing excessive voltage and destroying the elements of the power converter 3 And thermal destruction of the induction machine 1 can be avoided.

FIG. 1 is a block diagram showing an embodiment of the present invention. FIG. 2 is an equivalent circuit diagram of the induction machine according to the present invention. FIG. 3 is a block diagram showing a conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Induction machine 2 Current detector 3 Power converter 4 Current control means 5 Control command creation means 6 Adder 7 Switching command creation means 8 Test command creation means 9 Switching means 10 Protection detection means

i ··· Induction machine current v ··· Voltage command τ * ··· Torque command · φ ··· Magnetic flux command ωm ··· Induction machine speed ωs * ·· Slip command
I1 * ・ ・ ・ Torque control current command ω11 * ・ ・ Torque control frequency command
I2 * ・ ・ ・ Test current command ω12 * ・ ・ Test frequency command
I * ・ ・ ・ Switching current command ω1 * ・ ・ Switching frequency command
ST ... Operation flag
CH ... Switch flag
DT ... Protection flag
FR ... Forward / reverse rotation flag ω1set ... Frequency setting value
Vset ・ ・ ・ Voltage setting value
R1 ・ ・ ・ ・ Primary resistance
R2 ... Secondary resistance
l1 ... Primary leakage inductance
l2 ... ・ Secondary leakage inductance
M ... Mutual inductance
W1 ・ ・ ・ ・ Primary frequency
WS ··· Slip frequency

Claims (2)

A current detector for detecting the induction machine current, having a torque control current command I1 *, a torque control frequency command ω11 *, and current control means for inputting the induction machine current and outputting a voltage command, and the induction machine based on the voltage command In the induction machine control device that controls the torque of
A switching command generating means for inputting an operation flag and outputting a switching flag, a test frequency command ω12 * in which a voltage setting value Vset is input and a setting of at least twice the induction machine operating frequency range is set, the voltage setting value Vset and the test frequency Test command creation means for outputting a test current command I2 * set using the command ω12 *, the torque control current command I1 *, the torque control frequency command ω11 *, the test current command I2 *, and the test frequency command ω12 * Switching means for inputting a switching flag and outputting a switching current command I * and a switching frequency command ω1 *, and a protection detecting means for inputting the voltage setting value, the voltage command and the switching flag and outputting a protection occurrence flag. In addition, instead of the torque control current command I1 * and the torque control frequency command ω11 *, the switching current command I * and the switching frequency command ω1 * are input to the current control means. Induction motor control device. 2. The induction machine control device according to claim 1, wherein a forward / reverse rotation flag and a frequency set value are newly input to the test command creating means.

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