JPS6277891A - Device for detecting anomalous behavior of induction motor controlling device - Google Patents

Abstract

PURPOSE:To quickly detect the anomalous state such as an irregularity of a device, the disconnection of a power source circuit and the like by a method wherein the generation of an anomalous state of control of the titled induction motor is detected under the condition in which the primary current comes down lower than the prescribed value while the motor is being operated. CONSTITUTION:When an anomalous state is generated in the titled device or a power source circuit and the direct current signal 12a outputted from a three- phase full-wave rectifier 12 is made smaller than the reference signal 14a of the reference setting device 14, the output signal 13a of a comparator 13 is turned to a logical value '0'. Accordingly, the inversion signal 21a of the output signal of the comparator 13 outputted from an inversion circuit 21 is turned to '1', the output signal 17a of an AND circuit 17 is turned to '1', and the anomalous state of control in operation can be detected by the abnormal state detecting signal 20a outputted from an OR circuit 20.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an induction motor control device that controls an induction motor using variable voltage, variable frequency (hereinafter referred to as VVVF) including vector control, and particularly relates to an induction motor control device that controls an induction motor using a variable voltage, variable frequency (hereinafter referred to as VVVF) including vector control, and in particular, the present invention relates to an induction motor control device that controls an induction motor using variable voltage, variable frequency (hereinafter referred to as VVVF) including vector control. The present invention relates to an abnormality detection device for detecting abnormalities such as wire breakage.

[Technical background of the invention and its problems] In recent years, with the remarkable development of semiconductor technology, high-performance control has become possible by combining a VVVF control device and vector control in the field of motor control. Therefore, the use of induction motors is being reconsidered.

By the way, this vector control and V V V F Ill
Many announcements and proposals have already been made regarding control devices that combine m devices.

As is well known, vector control generates an induction-like primary current using a composite component of an excitation component current command <Id') corresponding to the field current of a DC machine and a torque component current command (IQ') corresponding to the iI armature current. It is something to control. Therefore, in vector control, in order to maintain the secondary magnetic flux corresponding to the field current even when the generated torque is zero, just as in the case of torque control using the armature current of a separately excited DC motor, the -order winding The configuration allows current control.

Furthermore, in the case of operation corresponding to the constant torque characteristic of a separately excited DC motor, the excitation component current command (Id') is fixed and control is performed to keep the secondary magnetic flux Φ2 constant, and the operation corresponding to the constant output characteristic is performed. In this case, magnetic flux weakening control can be performed in which the excitation component current command (Id') is adjusted in consideration of the follow-up delay of the secondary magnetic flux.

FIG. 6 shows an example of a configuration in which an induction motor is driven by a VVVF control device including such vector control. 1 in the figure is a VV for driving the three-phase induction motor 2
The VF control device 3 is an AC power supply. Further, 4 is a speed command device, 5 is a speed detector for detecting the speed of the induction electric motor t12, and 6 is a speed control device into which the speed command 4a of the speed command device 4 and the speed signal 5a of the speed detector 5 are input. With the device,
This speed control device 6 performs speed control calculations according to the deviations of these re-input signals, and calculates the torque component current reference 6a (Iq”
) is output. 7 is an excitation component current reference command device that outputs an excitation component current base $7a (Id'). Reference numeral 8 is a vector control arithmetic unit, and torque component current reference 6a (Iq
) and the excitation component current reference 7a (Id''>), the speed signal 5a is further input, vector control calculation is performed, and the primary current reference 8a (sine wave current reference) of the induction motor 2 is output.

9 is a current detector that detects the primary current of the induction motor [2;
0 is a current control device to which a primary current reference 8a and a primary current detection signal 9a are input, and this current control device 10 performs current control calculations according to the deviation of these re-input signals and outputs a voltage command value 10a. 11 is this voltage command value 10a
In a sine wave PWM control device, this sine wave PW
M control device [11ha VVVFIIJtll variable to device 1!
Timing signal 11a for pressure-variable frequency control
Output.

Therefore, in the induction motor control device having such a configuration, the VvVF control device 1 properly controls the torque and speed of the induction motor 2 by the timing signal 11a output from the sine wave PW M 11 m device 11. It becomes possible to do so.

However, in this induction motor control device, if an abnormality occurs in a part of the device, a state may occur where current cannot be supplied to the primary winding of the induction motor 2, or the induction motor 2
If a disconnection occurs in the wiring route to the induction motor 112,
A situation may occur where a normal current supply is no longer possible. .

[Object of the Invention] The present invention provides an induction electric motor system that can quickly detect abnormalities such as device abnormalities and disconnection of the power supply circuit in response to the above-mentioned problems.
An object of the present invention is to provide an abnormality detection device for a control device.

[Summary of the Invention] In order to achieve the above object, in the present invention, when an induction motor is driven using vector control, the excitation component current is transferred to the induction motor in order to ensure secondary magnetic flux even in a zero-torque control state. The system focuses on continuous supply to the primary winding, and is characterized by detecting the occurrence of a control abnormality when the primary current falls below a specified value during operation.

[Embodiments of the invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a case of constant secondary magnetic flux control with constant torque characteristics as an example of the circuit configuration of the control abnormality detection device according to the present invention, and the same components as in FIG. 6 are given the same symbols.

In the figure, 12 is a three-phase full-wave rectifier circuit that receives as input the current detection signal 9a from the current detector 9 provided in each phase of the primary winding of the induction motor 2, and 13 is the reference signal 14a of the reference setter 14.
and the output signal 12a (DC signal) of the full-wave rectifier circuit 12 as input, and outputs a signal with a logical value of "1" when the DC signal 12a exceeds the reference signal 14a. Also, 16.17. '1B is an AND circuit, 19
．． 20 is an OR circuit, 21 and 22 are inversion circuits, and 23 is a delay circuit.

A comparator 7 is connected to the AND circuit 16 through an OR circuit 19.
The output signal 13a of the AND circuit 16 is applied, and the control start command signal @15a is also input, and the output signal 1 of the AND circuit 16 is
6a is added to the OR circuit 19 as a self-holding signal.

The AND circuit 17 receives the output signal 21a of the inverting circuit 21, which receives the output signal 13a of the comparator 13, and the output signal 16a of the AND circuit 16. AND circuit 18 is AN
An inverting circuit 22 to which the output signal 16a of the D circuit 16 is input.
The output signal 22a and the control start command signal 15a are input. The OR circuit 20 receives the output signal 17a of the AND circuit 17.
and the output signal 23a of the delay circuit 23 into which the output signal 18a of the AND circuit 18 is input, and when either output signal has a logic value of ``1'', an abnormality detection signal 20a is output. Further, this OR circuit 20 receives the output of the abnormality detection signal 20a and outputs the signal as a self-holding signal.
A circuit input to the circuit 20 is formed, and this circuit is provided with resistors R1, R2, and a capacitor C, and constitutes a filter with an extremely small time constant to prevent malfunctions when the power is turned on. .

Next, the operation of the control abnormality detection circuit configured as described above will be described.

The average value of the DC signal 12a obtained by full-wave rectification of the current flowing into each phase of the primary winding of the induction motor by the three-phase full-wave rectifier 12 is the excitation component current reference (Id') in vector control.
and the torque component current reference ((q'). In other words, it is equal to the -order current amplitude reference 11'(-')2+(IQ'')2).

Therefore, in vector control, the DC signal 1 in the control state
The average value of 2a never falls below the excitation component current reference (Id"). Also, the excitation current 1lI in the stopped state
The primary current when controlling IJ is direct current, and the direct current signal 12
a matches ldN (It"-Id'). When the motor rotates, the DC signal 12a becomes a signal containing a ripple frequency six times the control frequency, and its lowest peak value is
1'×sinπ/3. The torque command value is almost zero! 1 (Ia'-0), the lowest peak value is ld×si
It becomes nπ/3. Therefore, the setting value of the reference setter 15 is a reference signal 14 that is slightly lower than Id'xsinπ/3.
It is set to be a.

Now, when there is no abnormality in the device or the power supply circuit, the control start command signal (XRR) 15a has a logical value of "1", current flows through the negative winding, and the output signal (CD) 13 of the comparator 13
When a becomes the logical value "1", the output signal (RR) of the AND circuit 16 also becomes the logical value "1".
When the output of circuit 16 (7) (No. 1 (RR) becomes ``1'', a self-holding signal is input to the OR circuit 19, so
This output signal (RR) is the control start command signal (XRR)
111 II is held until becomes the logical value "0". The output signal (RR) 17a of the AND circuit 16 has a logical value "
1'' state (control state), if an abnormality occurs in the device or the power supply circuit and the DC signal 12a output from the full-wave rectifier 12 becomes smaller than the reference signal 14a of the reference setter 14, the comparator The output signal 13a of No. 13 has the logical value “O
''. Therefore, since the inverted signal (CD) of the output signal of the comparator 13 output from the inverting circuit 21 becomes ``1'', the output signal (ERRI) of the AND circuit 17 becomes ``1''.
'', and the abnormality detection signal 2 output from the OR circuit 20
0a detects a control abnormality during operation. In addition, even if the control start command signal (XRR) has a logical value of ``1'', the output signal (RR) 16a of the AND circuit 16 has a logical value of ``1''.
', that is, the output signal 13a of the comparator 13 (
CD) does not change from the logical value ``0'' to ``1'', the output signal (RR) of the inverting circuit 22 has the logical value ``1'', so the output signal (XERR2) of the AND circuit 18 has the logical value ``1''. 1''. When this state continues for a certain period of time, the output signal (ERR2) is generated by the operation of the delay circuit 23.
Since the logical value becomes "1'', an abnormality at the start of control is detected by the abnormality detection signal 20a output from the OR circuit 20.

In this way, the output signal (ERRl) 17 of the AND circuit 17
a or the output signal (ERR2) 23a of the delay circuit 23 becomes 1", and once the OR circuit 20 outputs an abnormality detection signal with a logic value of "1", the OR circuit uses its self-holding input signal (ERRX) to , abnormality detection mode (ERR'“
1pa).

- By adding the circuit of this embodiment to the induction motor control device, it is possible to prevent current from flowing to the induction lightning vJ machine due to a malfunction of the device or a break in the wiring circuit of the power supply circuit, etc. at the time of starting control or after the start of control. Such abnormal modes can be quickly detected.

Next, other embodiments of the present invention will be described.

(1) In the embodiment S shown in FIG. As shown in the case, the current detection signal 9 from the It current detector provided in any two of the three phases of the three-phase secondary winding of the induction motor
When a is input to the three-phase full-wave rectifier 12, an input circuit as shown in FIG. 2 may be constructed in the preceding stage. That is, as shown in FIG. 2, the current signal 9a1 detected in two phases
Using the current signal 9a2, a current signal 9a3 corresponding to the remaining one phase is created by an arithmetic circuit equipped with an operational amplifier 24.

This arithmetic circuit consists of an operational amplifier 24 and resistors R3゜R4, R5.
(All resistance values are set equal.) Therefore, the amplification factor -
It constitutes a 11 times inverting and adding circuit.

Here, the relationship between the current signals 9al, 9a2.9a3 can be expressed as shown in FIG. 3 using a vector diagram.

(a) Although the embodiment shown in FIG. 1 uses constant magnetic flux control, it can also be applied to field weakening control.

FIG. 4 shows an example of the configuration when performing flux weakening control with constant output characteristics.

In FIG. 4, a conversion circuit 25 is provided in place of the reference setter 14 in FIG. The DC signal 12a is applied to the converter 13 and compared with the DC signal 12a output from the three-phase full-wave rectifier 12.

FIG. 5 is a diagram showing details of the internal configuration of the conversion circuit 25. As shown in FIG. 5, the conversion circuit 25 includes an operational amplifier 26 to which an excitation current reference signal 7a (Id'') is input, and resistors R6 and R7 to form an inverting amplifier circuit, and its output signal is compared as a reference signal 25a. Here, if the resistance value of the input resistor R6 is 1, the resistor R7 is set to be slightly smaller than sinπ/'3 as described above. Also, if the input signal (dN is inverted) This is to make the signal have the polarity as the reference signal 25a given to the comparator 13. Note that the ld-
The calculation method is well known and will therefore be omitted.

Furthermore, the capacitor C2 in the circuit is used to configure a temporary delay circuit together with the resistor R7, and the time constant is −〇2
R7 is set approximately equal to the crossing angular frequency (ω) of current control. This is to prevent the detection device from malfunctioning due to a delay in the response of the actual current to the current reference.

In each of the above-mentioned embodiments, the case where the abnormality detection circuit is configured with operational amplifiers and logical operation circuits has been shown, but even if the same processing as described above is performed by software using a microcomputer, abnormalities in the induction motor control device can be easily detected. It is something that can be done.

[Effects of the Invention] As described above, according to the present invention, in a control device that drives an induction motor by variable voltage and variable frequency control including vector control, a current that detects the current flowing in the primary winding of the induction motor is provided. a detection means, a DC conversion means for converting the current detection signal detected by the current detection means into a DC signal, and a DC signal obtained by the DC conversion means reaching a reference signal corresponding to the excitation component current reference of vector control. a discriminating means for discriminating whether or not the DC signal has reached the reference signal; The present invention includes a determination means for determining that there is an abnormality in the electric power supply circuit, and detects the occurrence of a control abnormality on the condition that the primary current flowing through the induction motor during operation does not reach a specified value. Accordingly, it is possible to provide an abnormality detection device for an induction motor control device that can quickly detect abnormalities such as device failure or disconnection of a power supply circuit.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram showing one embodiment of the present invention, FIG. 2 is a circuit configuration diagram showing the main part of another embodiment X of the present invention, and FIG. A vector diagram showing the relationship when determining one phase, FIG. 4 is a circuit configuration diagram showing the main part of another embodiment of the present invention, and FIG. 5 is a configuration showing details inside the conversion circuit in the same embodiment. Figure 6 is an example of a control if+ device that drives an induction motor using a VVVF control device including vector control? FIG. 1... VVVF control device, 2... induction motor, 3...
... AC power supply, 4 ... Speed command device, 5 ... Speed detector, 6 ... Speed control device, 7 ... Excitation component current reference command device, 8 ... Vector sub-part calculation device, 9...
Current detector, 10-...Current control m device, 11 - LE string wave P W M 1Iill Ill! Place, 12...
Three-phase full-wave rectifier, 13... Comparator, 14... Reference setter, 15a... Operation start command signal, 16-18...
・AND circuit, 19.20...OR circuit, 21.22
...Inverting circuit, 23...Delay circuit, 24°26...
- Operational amplifier, 25...conversion circuit. Fig. 1 1 person Fig. 4 Fig. 5 Fig. 5 Fig. 6

Claims (1)

[Claims] A control device for driving an induction motor by variable voltage and variable frequency control including vector control includes current detection means for detecting a current flowing in the primary winding of the induction motor, and a current detection signal detected by the current detection means. DC conversion means for converting into a DC signal; determination means for determining whether the DC signal obtained by the DC signal reaches a reference signal corresponding to an excitation component current reference for vector control; and operation of the control device. determination means for determining that there is an abnormality in the control device or the power supply circuit of the induction motor when a start command signal is input and the determination means determines that the DC signal does not reach the reference signal; An abnormality detection device for an induction motor control device, characterized in that: