JP2831777B2 - Power converter controller - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter control device used when an output from a power converter is supplied to a load via an isolation transformer.

[Conventional technology]

FIG. 2 is a block diagram showing the configuration of a conventional power converter control device. In this figure, the power from an AC power supply 1 is output after being controlled by a variable voltage variable frequency by a power converter 2 such as an inverter. Is done.

The AC output from the power converter 2 is sent to a rectifying circuit including a rectifying element such as a diode via the insulating transformer 3 and rectified therein. Then, the direct current from the rectifier circuit 4 is supplied to the load 7 after being smoothed by a smoothing circuit composed of the reactor 5 and the capacitor 6.

At this time, the voltage input to the load 7 is detected by the voltage detector 8, and the feedback signal, that is, the detection signal is sent to the phase control circuit 9. The phase control circuit 9 controls the phase of a switching element such as a thyristor included in the power converter 2 based on the detection signal.

The detection signal from the voltage detector 8 is an overvoltage determination circuit.
It is also sent to 10, where it is determined whether the voltage input to the load 7 is in an overvoltage state. Then, when it is determined that the state is in the overvoltage state, the protection logic control circuit 11 sends an operation stop signal to the power converter 2 to stop the operation. On the other hand, if it is determined that the state is not the overvoltage state, the protection logic control circuit 11 sends an operation permission signal to the power converter 2 to continue the operation as it is.

[Problems to be solved by the invention]

By the way, when a failure occurs in the voltage detector 8 and the feedback amount becomes zero, the phase control circuit 9
The phase control is performed such that the conduction time of the switching elements in the inside becomes long. Therefore, the voltage applied to the load 7 is also excessive, but since the voltage detector 8 itself has failed, the overvoltage determination circuit 10 and the protection logic control circuit 11 do not operate effectively.

As a result, an overvoltage occurs in the load circuit including the load 7, which may be damaged.

The present invention has been made in view of such circumstances,
An object of the present invention is to provide a power converter control device capable of effectively preventing a load circuit from being damaged even if a voltage detector used for detecting a feedback signal fails.

[Means for solving the problem]

As a means for solving the above-described problems, the present invention supplies an output from a power converter to a load via an insulating transformer, and performs feedback control of the power converter based on detection of the output supplied to the load. In the power converter control device, a load-side input voltage detecting means connected in parallel to the load and detecting a load-side input voltage for the feedback control, and a transformer attached to a secondary side or a primary side of the insulating transistor Side voltage detection means, first overvoltage determination means for determining whether or not the load side input voltage is in an overvoltage state based on a detection signal from the load side input voltage detection means, and A second overvoltage determination means for determining whether or not the power converter is in a state; and a combination of respective determination signals from the first and second overvoltage determination means. And protection logic control means for sending a rotation stop signal or operation permission signal, a configuration equipped with.

(Operation)

In the above configuration, it is assumed that a failure has occurred in the load-side input voltage detection means and the feedback amount has become zero. Then, since the power converter increases its output, the load side input voltage tends to become excessive.

However, at this time, since the secondary voltage and the primary voltage of the insulating transformer are also going to be excessive, the second overvoltage determination means outputs an overvoltage determination signal to the protection logic control means by the transformer side voltage detection means.

The protection logic control means determines that a failure has occurred in the load-side input voltage detection means by the overvoltage determination signal from the second overvoltage determination means even if the overvoltage determination signal is not sent from the first overvoltage determination means. Assuming that the operation of the power converter is stopped.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIG. However, the same components as those in FIG. 2 are denoted by the same reference numerals, and the description thereof will not be repeated.

A primary side of an instrument transformer (PT) 12 as a transformer-side voltage detecting means is connected to a secondary side of the insulating transformer 3 via a connection point with a diode in the rectifier circuit 4.

A second overvoltage judging means 13 is connected to the secondary side of the instrument transformer 12, and the judgment signal is sent to the protection logic control means 11.

The judgment signal from the first overvoltage judgment means 10 is also sent to the protection logic control means 11, and the protection logic control means 11 outputs the judgment signals from the first and second overvoltage judgment means. An operation stop signal or an operation permission signal is sent to the power converter 2 based on the combination.

Here, when the first and second overvoltage determination means 10 and 13 determine that an overvoltage has occurred, an H signal is output; otherwise, an L signal is output.
The logical contents followed by 11 can be represented as in the following table.

As is clear from the above table, the protection logic control means 11
Is logically configured to stop the operation of the power converter 2 when at least one of the first and second overvoltage judging means 10 and 13 judges an overvoltage. Next, the operation of the present embodiment configured as described above will be described based on the above table.

First, it is assumed that both the load-side input voltage detection means 8 and the transformer-side voltage means 12 function normally, and that there is no abnormality in the main circuit system. In this case, both the first and second overvoltage judging means 10 and 13 output the L signal to the protection logic control means 11, and the protection logic control means 11 outputs the L signal, that is, the operation permission signal to the power converter 2. (Logic (a)).

However, even if both the load-side input voltage detecting means 8 and the transformer-side voltage detecting means 12 are functioning normally, if an abnormality occurs in the main circuit system, both of these detecting means detect an overvoltage. . Therefore, in this case,
Both the first and second overvoltage judging means 10 and 13 output an H signal to the protection logic control means 11, and the protection logic control means 11 outputs an H signal, that is, an operation stop signal to the power converter 2 (logic (b) )).

When the transformer-side voltage detecting means 12 functions normally and there is no abnormality in the main circuit system and only the load-side input voltage detecting means 8 fails, the first and second overvoltage determining means are provided.
10 and 13 initially output the L signal. However, the detection amount input by the phase control circuit 9 becomes zero due to the failure of the load-side input voltage detection means 8, so that the phase control circuit 9 sets the phase so that the conduction time of the switching element of the power converter 2 becomes longer. Perform control. Therefore, the output voltage on the secondary side of the insulating transformer 3 tends to be excessive, and the second overvoltage determination means
13 outputs the H signal. As a result, the protection logic control means 11 outputs an operation stop signal to the power converter 2 (logic (c)). That is, even if the load-side input voltage detecting means 8 fails and the feedback amount becomes zero, it is possible to prevent the load circuit from being damaged by an overvoltage that is to be generated thereafter.

If the load-side input voltage detection means 12 functions normally and there is no abnormality in the main circuit system and only the transformer-side voltage detection means 12 fails, the second overvoltage determination means 13 outputs an H signal. Also, the operation of the power converter 2 is stopped (logic (d)).

In the above-described embodiment, the example in which the transformer-side voltage detecting means 12 is mounted on the secondary side of the insulating transformer 3 has been described.

〔The invention's effect〕

As described above, according to the present invention, the transformer-side overvoltage detecting means is provided in addition to the load-side input voltage detecting means, and the detection results of both detecting means are determined by the first and second overvoltage determining means, respectively. Since the control related to the operation stop or operation permission of the power converter is performed based on the combination of the determination results of the determination means, even if the load-side input voltage detection means used for detecting the feedback signal fails, the load can be reduced. Circuit damage can be effectively prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional example. 2 ... power converter, 3 ... insulating transformer, 7 ... load,
8: load-side input voltage detection means, 10: first overvoltage determination means, 11: protection logic control means, 12: transformer-side voltage detection means, 13: second overvoltage determination means.

Claims (1)

(57) [Claims] 1. A power converter control device for supplying an output from a power converter to a load via an insulating transformer and performing feedback control of the power converter based on detection of the output supplied to the load. A load-side input voltage detection unit that is connected in parallel to a load and detects a load-side input voltage for the feedback control; a transformer-side voltage detection unit attached to a secondary side or a primary side of the insulating transformer; Based on the detection signal from the side input voltage detection means,
First overvoltage determining means for determining whether the load-side input voltage is in an overvoltage state; second overvoltage determining means for determining whether the transformer-side voltage is in an overvoltage state; Protection logic control means for sending an operation stop signal or an operation permission signal to the power converter based on a combination of the respective judgment signals from the second overvoltage judgment means. apparatus.