JPH01255476A - Controller for electric power conversion device - Google Patents

Abstract

PURPOSE:To avoid breakage, by a method wherein a control means is switched to a protecting means, outputting a protection signal to shift the value of current of a main circuit for the control means to zero, when the abnormality of the control means is detected and, thereafter, the protecting means is switched to the waiting control means after confirming that the value of the main circuit current is zero. CONSTITUTION:The power of an AC power source 2 is converted by a power converting device 4 into a variable frequency AC power to effect the variable speed driving of a synchronous motor 5. In order to control the converting device 4, the title controller is provided with a control unit 20 having a normally used control circuit 11, a preliminary control circuit 12 waiting as a preliminary circuit and a switching device 30 while a current actual value signal I from a current transformer 3, a speed actual value signal N from a speed generator 6 and a speed objective value signal N* from an external source are inputted into the control circuits 11, 12 respectively. A protective circuit 15 is provided in the control unit 20 to output an ignition pulse shifting the main circuit current of the converting device into zero while the switching device 30 selects a protecting signal E to nullify the main circuit current surely and, thereafter, the control circuit is switched.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention provides a power converter system that continues operation by switching to a standby control means when an abnormality occurs in the control means controlling the power converter. The present invention relates to a control device for a conversion device.

[Prior Art] FIG. 3 is a circuit diagram showing a general example of driving a motor with a power conversion device. In FIG. 3, a power converter 4, which is, for example, a frequency converter with a DC intermediate circuit, converts AC power from an AC type a2 into AC power of a desired frequency, and uses this AC power to power, for example, a synchronous motor 5. It constitutes a so-called commutatorless motor that is driven at variable speeds. Here, reference numeral 8 denotes a control circuit that controls the power converter 4, and for example, inputs a speed target value signal N0 from the outside manually, and outputs an actual current value signal from the current transformer 3 connected to the AC power source 2.
, and by inputting an actual speed value signal N from a speed transmitter 6 connected to the electric motor 5 to this control circuit 8,
An ignition pulse signal is given from the control circuit 8 to the power converter 4 so that the speed of the electric motors maintains the target value N''' while suppressing the current to prevent the power converter 4 from overcurrent. .

When this electric motor 5 plays an important role in a plant, what happens if an abnormality occurs in the control circuit 8? If D becomes disabled, not only will the electric JR5 become unable to drive, but
The entire plant may shut down. Therefore, in order to avoid this, important power conversion equipment is equipped with multiple (for example, two sets) of control circuits, and if the normally used control circuit breaks down, it can be switched to the standby control circuit. We are trying to continue operation.

FIG. 4 is a block diagram showing a conventional example of a power conversion device equipped with 2&ll control circuits. In this Figure 4,
1O is a control device which is the same as the one shown in FIG. 3 except for its internal configuration which is different from the control device 8 shown in FIG. Does this control device 10 control the power conversion device 4? It is composed of two control Jn circuits 11, 12, each having the function of switching, and a switching device 13.

Recontrol 1 circuits 11 and 12 both have a speed target value signal N.
0, the speed actual value signal N and the current actual value signal I are input, and based on these, the control circuit 11 generates the ignition pulse signal C1, and the control circuit 12 generates the ignition pulse signal C2.
Each outputs separately.

Here, if the control circuit 11 is set to normal use and the control circuit 12 is set to standby, the switching device 13
The status signal A1 to i! becomes "regular" and i! ili iT
The ignition pulse signal C1 outputted from the Q circuit 11 is applied to the power conversion device 4 via the switching device 13. Further, since the status signal A2 from the switching device 13 to the control circuit 12 is "standby", the firing pulse signal C2 of the control circuit 12 is blocked.

Here, when it is detected that an abnormality has occurred in the control circuit 11, a failure signal B1 is sent from the control circuit 11 to the switching device.
Since the switching device 13 switches the ignition pulse signal from 01 to 02 and sends it to the power converter 4, the power converter 4 can continue operating.

(Problem to be solved by the invention) By the way, when the control circuit 11 is on standby due to a failure, the control circuit 1
2, if the switching is performed while the power conversion device 4 is still energized, a sudden change in the ignition phase may even cause a commutation failure.

Therefore, upon detection of an abnormality, the ignition pulse signal C1 is first shifted in the direction in which the main circuit current of the power converter 4 becomes zero.

In this case, the ignition pulse signal C2 of the control circuit 12 has already been similarly shifted during standby. Next, power converter 4
After confirming that the main circuit current has become zero, the switching device 13 switches the ignition pulse signal from 01 to 02, and then applies it to the control circuit 12 to return the main circuit current to its original value. Cancels the shifted part.

When switching the control circuit from the regular side to the standby side,
The above procedure must be followed, but if the fault in the normal control circuit is in the ignition pulse generator, the pulse shift that reduces the main circuit current to zero cannot be performed, and therefore the control circuit in standby cannot be This causes the inconvenience of not being able to switch.

In addition, in a control circuit that uses a microcomputer and performs direct control (DDC) using digital quantities, even if the microcomputer malfunctions or goes out of control, the main circuit current cannot be reduced to zero, so the failure may spread or the entire plant may be damaged. There is also the risk of more accidents, such as the suspension of operations.

SUMMARY OF THE INVENTION An object of the present invention is to provide a power converter equipped with a plurality of control circuits so that even if the normally used control circuit has a failure, the power converter can be reliably switched to a standby control circuit. The purpose is to prevent the vehicle from becoming inoperable.

[Means to solve the problem]

A power conversion device composed of semiconductor switching elements is equipped with a plurality of sets of control means for controlling the power conversion device, and any one of these control means and the power conversion device is combined to detect an abnormality in the control device during operation. A protection means for outputting a protection signal to control the main circuit current of the power conversion device to zero in a power conversion device that switches to a standby control device and continues operation if detected, and a control device that is in use. a first signal switching means for switching the output signal of the abnormality control means to the protection signal when an abnormality is detected; and a first signal switching means for switching the output signal of the abnormality control means to the protection signal; and a second signal switching means for switching to the output signal of the other control means therein.

[Effect]

The present invention includes a plurality of control means, and when the regular control means is out of order, the main circuit current of the power conversion device to be controlled is controlled in the direction of zero, and after detecting zero current, the control means on standby However, in preparation for a failure in which the main circuit current cannot be controlled in the zero direction, a protective means that outputs a protection signal that reduces the main circuit current to zero is installed in advance to detect abnormalities in the regular control means. If detected, the first signal switching means switches from the regular control means to the protection means, and then, when zero main circuit current is detected, the protection means is switched to the standby control means, thereby preventing runaway of the power converter and controlling the power converter. Aim for reliable switching of methods.

[Embodiment] FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, a so-called non-commutator motor that converts AC power from AC 1tai2 into variable frequency AC power by a power conversion device 4 to drive a synchronous motor 5 at variable speed is configured as follows. This is the same as the case of the circuit already described in FIG. In addition, in order to control this power conversion device 4, a normally used control circuit 11 and a control circuit 12 that is on standby as a standby in case this control circuit 11 breaks down are selected, and the power conversion is performed by selecting one of the two. There is a control device 20 that is equipped with a switching device 30 that sends an ignition pulse signal of a different sign to the device 4, and these control circuits 11 and 12 are connected to a current transformer installed in the AC type 1flX2. The current actual value signal I from the motor 3, the actual speed value signal N1 from the speed transmitter 6 coupled to the motor 5, and the speed target value signal N1 given from the outside are respectively inputted. This is also the same as in the conventional circuit described above in FIG.

In the present invention, a protection circuit 15 is provided inside the control device 20.
The protection circuit 15 outputs an ignition pulse signal as a protection signal with the symbol E, which shifts the main circuit current of the power conversion device 4 to zero, and the switching device 30 If this protection signal E is selected and given to the power converter 4, the main circuit current of the power converter 4 will be reliably brought to zero even if the abnormality in the control circuit in use is in the ignition pulse generator. be able to.

When the control circuit 11 is currently in use, the control 711 circuit 12 is in reserve, so the status signal AI is "normally used" and the status signal A2 is "standby", and the control is performed accordingly. The ignition pulse signal C1 outputted from the circuit 11 passes through the switching device 30, becomes an ignition pulse signal of the sign, and is applied to the power converter 4. At this time, the protection signal E from the protection circuit 15 is blocked by the switching device 30 and is not transmitted to the power conversion device 4.

When it is determined that an abnormality has occurred in the control device 11 in use, the failure signal B1 from the control circuit 11 to the switching device 30 changes from "normal" to "abnormal", and the switching device 30 , the ignition pulse signal given to the power converter 4 is switched from B1 to E. In other words, an ignition signal that shifts the main circuit current of the power conversion device 4 to zero will be given, so when it is detected that the current actual value signal becomes zero, the switching device 30 will switch off the protection from the protection circuit 15. Since the signal E is switched to the ignition pulse signal C2 from the control circuit 12, the operation of the control circuit 12 during standby causes the %
:'i The 4-way current of the changing device will rise from zero and will resume the previous operation.

FIG. 2 is a wiring diagram showing the inside of the switching device used in the embodiment circuit shown in FIG.
are a first switching signal generation circuit 31, a first signal switching circuit 32,
Second switching signal generation circuit 41 and second signal switching circuit 42
It consists of Further, the signal switching circuit 32 used here includes AND elements 33 and 34 and an OR element 4.
Similarly, the signal switching circuit 42 also includes AND elements 43 and 44 and an OR element 45.

The operation of the switching device 30 shown in FIG. 2 is as follows.
When the control circuit 11 is currently being used and the control circuit 12 is in the standby state, the status signal AI output by the switching signal generation circuit 41 is "normally used" and the status signal A2 is "standby". The output signal F of the switching signal generation circuit 41 outputs a logic 1 signal. Therefore, the ignition pulse signal C1 from the control circuit 11 is output to the signal switching circuit 32 via the AND element 43 and the OR element 45 that constitute the signal switching circuit 42, but the ignition pulse signal C1 from the control circuit 12 Pulse signal C2
is blocked by AND element 44.

If the control circuit 11 is normal at this time, since the failure signal B1 is "normal", the output signal J from the switching signal generation circuit 41 to the switching signal generation circuit 31 is also "normal".
Therefore, the output signal G of the switching signal generation circuit 31 is a logic 1 signal, and therefore the above-mentioned firing pulse signal with the symbol C1 is as follows.
The protection signal E output from the protection circuit 15 is given to the power converter 4 as a signal via the AND element 33 and the OR element 35 that constitute the signal switching circuit 32. This is blocked by the product element 34.

Here, it is assumed that an abnormality occurs in the control circuit 11 in use.

This abnormality may be discovered by the self-diagnosis function provided in the control circuit 11, but as a result of this abnormality, system failure may occur. II (for example, occurrence of overcurrent)
In some cases, the problem can be determined by detecting it. As a result of this abnormality detection, the failure signal B1 from the control circuit 11 becomes "abnormal", and in response to the change in the signal B1 to "abnormal", the switching signal generation circuit 41 changes the output signal F from a logic 1 signal to a logic 1 signal. Along with changing it to zero signal,
Change signal J from "normal" to "abnormal J."

The switching signal generating circuit 31 changes the output signal G from a logic 1 signal to a logic 0 signal in response to the signal J switching to "abnormal", so that the signal that was previously output from the signal switching circuit 42 -( The H signal is blocked here, but
Since the protection signal E from the protection circuit 15 is applied to the power converter 4 via the AND element 34 and the OR element 35, the power converter 4 shifts its main circuit current to zero. At this time, the output signal H of the signal switching circuit 42 is changed from the ignition pulse signal C1 outputted by the control circuit 11 to the control circuit in conjunction with the switching of the output signal F of the switching signal generation circuit 41 to a logic zero signal. 12 outputs the ignition pulse signal C2.

Since the current transformer 3 detects that the main circuit current of the power converter 4 has become zero, when the actual current value signal I input to the switching signal generating circuit 31 becomes zero, this switching signal generating circuit 31 Since the output signal G returns to the logic 1 signal again, the signal switching circuit 32 blocks the output of the protection signal E and supplies the signal H from the switching signal generation circuit 41 as it is to the power converter 4. This signal H is the ignition pulse signal C2 output by the control circuit 12 as described above.

In this way, when an abnormality occurs in the control circuit 11 that is regularly used,
The ignition pulse signal input to the power conversion device 4 is automatically switched in the order of signal C1 output by the control circuit 11 → signal E output from the protection circuit 15 → signal C2 output from the control circuit 12, and the Although the converter 4 requires some downtime, such as a time to confirm that the main circuit current is zero and a time to switch the ignition pulse signal, it is possible to continue operation.

〔Effect of the invention〕

According to this invention, when it is detected that an abnormality has occurred in the commonly used control means that controls the power conversion device configured with semiconductor switching elements, a protection signal is activated to shift the main circuit current of the power conversion device to zero. After confirming that the main circuit current has become zero, we switch to the other control means that is on standby.
Even if an abnormality occurs in the regular control means, even in the ignition pulse generator, it can be transmitted to the standby control means without the power converter becoming uncontrollable or in a dangerous state such as runaway. Since the power converter can resume operation after only a short period of suspension, there is no major impact on the plant or system, and there is no possibility that an abnormality in the control means will spread to the power converter and cause the converter to restart. The risk of damage can be avoided.

[Brief Description of the Drawings] Fig. 1 is a block diagram showing an embodiment of the present invention, and Fig. 2 is a wiring diagram showing the inside of the switching device used in the embodiment circuit shown in Fig. 1. , Figure 3 is a circuit diagram showing a general example of driving a motor with a power conversion device, and Figure 4 is a circuit diagram showing a general example of driving a motor with a power conversion device.
1 is a block diagram showing a conventional example of a power converter device including a set of control circuits. 2... AC power supply, 3... Current transformer, 4... Power converter, 5... Electric motor, 6... Speed transmitter, 8...
Control circuit, 10°20...Control device, 11.12...
・Control 71 circuit, 13.30...Switching device, 15...
- Protection circuit, 31.41... first switching signal generation circuit,
32.42...Signal switching circuit, 33.34.43.4
4...Mo 1 Figure 2

Claims (1)

[Claims] 1) A power conversion device composed of semiconductor switching elements is provided with a plurality of sets of control means for controlling the power conversion device, and when any of these control means and the power conversion device are operated in combination, an abnormality in the control means is detected. In the power converter, if it detects this, it switches to the standby control means and continues operation.
a protection means for outputting a protection signal that makes the main circuit current of the power converter zero; and a first signal for switching the output signal of the abnormality control means to the protection signal when an abnormality is detected in the control means in use. It is characterized by comprising a switching means, and a second signal switching means that switches the protection signal to the output signal of another control means on standby if zero main circuit current of the power conversion device is detected after the switching. A control device for a power conversion device.