JPH01264573A - Reset circuit for power converter - Google Patents

Abstract

PURPOSE:To simplify a system configuration and reduce cost thereof by inputting a common reset signal to a plurality of power converters even when several power converters out of a plurality thereof are stopped by detecting abnormality. CONSTITUTION:An inverter device is composed of a conversion circuit 1 constituted of a power semiconductor element, a driver circuit 2 for the conversion circuit 1, a control circuit 3, a protective circuit 4, a reset circuit 5, a reset terminal 6 and a logic gate 7, outputs variable AC power and variable frequency, and variable-speed operates an induction motor. A gate circuit 8 is mounted and organized of a logical element at that time, an output signal from the protective circuit 4 and a reset signal are input to the gate circuit 8, and transmission over the reset circuit 5 of the reset signal is discriminated by the output signal level of the protective circuit 4. Accordingly, since the gate circuit 8 receives the reset signal only when the protective circuit 4 is operated and an output from the circuit 8 is interrupted, the gate circuit 8 conducts a reset operation only in the case of the abnormal stop of the conversion circuit 1.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a reset circuit that restarts a power converter that has stopped due to an abnormality, and in particular, the present invention relates to a reset circuit that restarts a power converter that has stopped due to an abnormality. The present invention relates to a reset circuit for a power conversion device in which restarting is performed by a reset operation only when

[Prior Art] Hereinafter, an inverter device that outputs variable AC power and variable frequency and operates an induction motor at variable speed will be described as an example of a power conversion device.

FIG. 2 is a block diagram showing an inverter device having a conventional reset circuit. In the figure, (1) is a conversion circuit composed of power semiconductor elements (hereinafter referred to as power elements) that generate arbitrary AC voltage and frequency, and (2) is a conversion circuit for driving the power elements of conversion circuit (1). The drive circuit (3) is a control circuit that controls the power element, and is a circuit that outputs a drive pattern of the power element to control the rotation speed of the induction motor.

(4) is a protection circuit that protects the inverter device from abnormal mode, (5) is a reset circuit that initializes the protection circuit (4) and control circuit (3), and (6) is a reset circuit that operates the reset circuit (5). The reset terminal (7) provided for the side that uses the inverter device for operation is a logic gate that receives the outputs of the control circuit (3) and the protection circuit (4), and is an AND gate in this example. . .

Next, the operation will be explained. The conversion circuit (1) converts the DC power supplied from the DC power supply DC to the primary side (P and N) into AC power, and also controls the voltage and frequency of the AC power to convert U and V.

The rotational speed of an induction motor (not shown) connected to W is changed.

When the load current detector CT detects an abnormal mode in the inverter (for example, the occurrence of an abnormality such as an abnormal increase in the motor current), the protection circuit (4) inverts the logic level of its output and performs an AND The output from the control circuit (3) to the drive circuit (2) is cut off via the gate (7). As a result, the power element is turned off (non-conductive), the inverter device is stopped, and the inverter device and the induction motor are electrically disconnected to prevent damage to the inverter device.

Therefore, if an abnormal mode is detected in the inverter and the inverter stops (in this case, it is generally equipped with a function to detect an abnormality and display that it has stopped).
In order to operate the inverter device again, it is necessary to cancel the operation of this protection circuit, and the reset circuit (5) and the circuit configured to achieve this purpose by inputting an external signal are used. This is the reset terminal (B). If a reset signal is input, the protection circuit will not be canceled and the control circuit will also be reset.
After the reset input, the induction motor gradually increases its rotation speed from a stopped state until it reaches the target rotation speed.

[Problems to be Solved by the Invention] Since the conventional inverter device was configured as described above, as shown in FIG.
a), (10b) - (10c) - (10n) to create multiple load motors (20a), (20b), (20c
) - (2On) and the reset terminal is shared, if a reset signal is input when one inverter stops abnormally, the reset signal or manual input is applied to other normal inverters. In order to solve this problem, it is necessary to detect the abnormal condition externally and set up a relay sequence.

This invention was made in order to solve the above-mentioned problems, and a reset signal is accepted for the inverter device which is stopped due to the activation of the protection circuit due to abnormal mode detection, and the inverter device is returned to normal operation. Reset of a power converter device that has a reset circuit configured so that even if a reset signal is input to the inverter device while operating in the operating state, the inverter device does not receive the signal and continues to operate in the same state as it was before the reset signal was input. The purpose is to obtain a circuit.

[Means for Solving the Problems] In the reset circuit of the power conversion device according to the present invention, the protection circuit operates based on the output of the detection circuit that detects an abnormality,
A gate circuit is provided that receives a reset signal only when the output of the power converter is cut off by the operation of this protection circuit.

[Operations] In this invention, the gate circuit operates the protection circuit based on the output of the detection circuit that detects an abnormality, and accepts the reset signal only when the output of the power conversion device is cut off. The reset operation is performed only when the is stopped due to an error.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
In the figure, (1) to (7) are the same as those with the same reference numerals in FIG. (8) is a gate circuit, which is composed of logic elements, receives the output signal of the protection circuit (4) and the reset signal from the reset terminal (6), and receives the output signal of the protection circuit (4) and the reset signal from the reset terminal (6).
This circuit determines (discriminates) whether or not to transmit the reset signal from the reset terminal (6) to the reset circuit (5) based on the output signal level of the reset terminal (6). In this embodiment, as shown in the figure, it is constructed by combining an AND gate and a NOT gate, and the output of the protection circuit (4) is inputted via the NOT gate.

Next, the operation will be explained. The operations (1) to (7) are the same as in the case of FIG. 2. The feature of this embodiment is that a gate circuit (8) is added.

During normal operation of the inverter device, the output signal of the protection circuit (4) is sent to the reset terminal (6) at the gate circuit (8).
Since the reset signal from the inverter is not transmitted to the set circuit (5), the inverter device does not perform a reset operation even if a reset signal is input from the reset terminal.
The previous operating state will continue.

Inverter device detects abnormal mode and protects circuit (4)
If the protection circuit (4) operates, the output signal of the protection circuit (4) will be a signal whose logic is inverted compared to the normal state described above, so in this case,
Since the gate circuit (8) operates so that the reset signal from the reset terminal (6) becomes effective for the set circuit, that is, the gate circuit (8) is closed, so by inputting the reset signal, the protection circuit is activated. The operation (4) is canceled, and unless the inverter device is again detected to be in an abnormal mode, the rotational speed of the load motor will quickly reach the set value.

In addition, in the above embodiment, a logic element is used in the gate circuit, but it is also possible to configure it by combining analog elements and mechanical contacts such as relays depending on the type of signal representing the reset signal and the protection circuit operating state. It is.

[Effects of the Invention] As explained above, the present invention accepts the reset signal only when an abnormal mode is detected, the protection circuit is activated, and the output of the power conversion device is cut off. In a load operation control system using multiple power converters, even if one or several of them stop due to abnormality detection, normal operation can be restored by inputting a common reset signal to multiple power converters. Since only the stopped machine can be reset and restarted without interfering with machine operation, there is no need to provide individual reset signals for multiple power converters, making the system configuration simple and inexpensive. There is a certain effect.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a block diagram showing an inverter device having a conventional reset circuit, and Fig. 3 is a block diagram showing operation by multiple inverter devices and commonization of reset signals. FIG. In the figure, (1) is a conversion circuit, (2) is a drive circuit, (
3) is a control circuit, (4) is a protection circuit, (5) is a reset circuit, (6) is a reset terminal, (7) is an AND gate,
(8) is a gate circuit. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] When the protection circuit operates based on the output of the detection circuit that detects an abnormality in the power conversion device and the output of the power conversion device is cut off, this state is canceled based on the reset signal input by the reset operation and the power conversion starts. A reset circuit for a power converter device for restarting the device, characterized in that the reset circuit is provided with a gate circuit that accepts a reset signal only when the protection circuit operates and the output of the power converter device is cut off.