JPH02193571A - Reset of control circuit of power converting device - Google Patents

Abstract

PURPOSE:To improve operability by providing a power source voltage detecting means and by detecting a distinction between an open circuit and a close circuit of a power source switching element. CONSTITUTION:A power converter is composed of a power source switching element 2, a power rectifier 3, a DC smoothing section 4 and a power inverter 5, and feeds a load 6. A switching regulator 7 and a control circuit 8 are also provided. A power source voltage detection circuit 9 which identifies an existence of an input power source of the power rectifier 3 is attached to supply the output to the control circuit 8. As a result, the control circuit 8 can carry out a reset operation forcibly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for resetting a control circuit of a power converter configured to supply control circuit power from a DC smoothing section of the power converter.

[Prior art and its problems]

Conventionally, in power conversion devices, the control circuit power source has generally been obtained from an AC power source through a transformer, a rectifier circuit, and a constant voltage circuit.

Recently, a method of obtaining control circuit power from the DC smoothing section of a power conversion device via a switching regulator (hereinafter referred to as the switching regulator method) has been adopted because it is advantageous for downsizing the device and coordinating the power circuit and the control circuit. has become widely used. An example of this is shown in FIG.

Figure 3 shows the main part configuration of the conventional example, where 1 is 1 source, 2
is a power supply switch, 3 is a forward conversion section, 4 is a DC smoothing section, 5 is an inverse conversion section, 6 is a load, 7 is a switching regulator, 8
is the control circuit. Here, in particular, the system for obtaining power for the control circuit 8 includes the control circuit 8 and a switching regulator 7 that obtains voltage from the DC smoothing section 4 and supplies control power to the control circuit 8.

Therefore, in this type of switching regulator system, sufficient functionality can be obtained from both control and protection points of view by detecting the DC voltage in the DC smoothing section.
There is basically no need to detect a single source of alternating current. On the other hand,
Since the source of the control circuit power source is a DC smoothing section with a large capacity, it takes a long time for the pressure in the control circuit to disappear even if the power source is cut off from a stopped state of the device.

Furthermore, there is a system that does not have a special circuit for maintaining a failure state or resetting a control state, and is configured to reset the above-mentioned state upon loss of control power supply.

This method allows any number of branch circuits to be reset simultaneously by turning off and turning on the power, and is advantageous when the configuration and number of branch circuits are not determined.

However, if a switching regulator-type power conversion device is used as a branch circuit in a system using this method, it takes a long time for the voltage in the control circuit to disappear, and the power must be shut off for a long time to reset the state. This is not desirable from the viewpoint of operability.

[Means for solving problems]

In view of the above-mentioned points, it is an object of the present invention to provide a method that can be reset by a short power interruption when used as a branch circuit of the above-mentioned system, while taking advantage of the advantages of the switching regulator system.

Therefore, the power supply voltage detection means is provided, and the detection means has a sufficient function of distinguishing between open and closed circuits of the power switch, that is, detecting the presence or absence of the power supply voltage of the device, and has an extremely simple circuit configuration. It is something.

[For production]

When the power source voltage detecting means detects the power supply voltage being restored after detecting a non-voltage state of the power supply voltage for a certain period of time, the control circuit can forcibly perform a reset operation.

〔Example〕

1 and 2 show the main structure of an embodiment of the present invention similar to FIG. 3 and its power supply voltage detection circuit portion, where 9 is a power supply voltage detection circuit. In the figure,
The same reference numerals as in FIG. 3 indicate parts having the same functions.

Here, the power supply voltage detection circuit 9 includes a photocoupler 91.degree. resistor 12 and a diode 93.

That is, in FIG. 1, a power supply voltage detection circuit 9 for obtaining the input power of the forward conversion section 3 is provided, and the output of the power supply voltage detection circuit 9 is supplied as a signal to the control circuit 8.

The power supply voltage detection circuit 9 may be of any type as long as it can identify whether or not the device is powered on. This will be explained in detail with reference to FIG. 2 as an example.

In FIG. 2, the power supply voltage detection circuit 9 is a photocoupler 9
The primary side diode of 1 is connected in antiparallel with a diode 93 for reverse voltage protection, and a resistor 92 for current limiting.
connected to the device's power supply via.

With this configuration, two of the photocouplers 91
When the power supply switch 2 is closed, the transistor on the next side is in the on state for about half a cycle of the voltage of the power supply l, and is in the off state for half a cycle. When the power switch 2 is open, the photo coupler 91
The next transistor is only in the off state.

Therefore, by checking in the control circuit 8 whether or not the transistor on the secondary side of the photocoupler 91 is in an on state, it is possible to know whether the power supply is present, that is, whether the rA switch 2 is open or closed. Further, the time from the detection of ON and OFF of the transistor on the secondary side of the photocoupler 91 to the determination of opening/closing of the power switch 2 may be slow enough to correspond to human senses.

Note that when the control circuit 8 includes a CPU, the voltage of the transistor on the secondary side of the photocoupler 91 is connected to one input terminal of the CPU, and the photocoupler 9 is connected to the CPU for a part of the time.
An open circuit in the power switch 2 can be detected because the transistor on the secondary side of the power supply switch 1 is not turned on.

After the CPU detects the open circuit of the switch for a certain period of time during the failure state holding operation, when it detects the closed circuit, the CPU issues a command to forcibly reset all control circuits.

Here, a photocoupler is used as a simple example, but there are other methods such as step-down and insulation using a transformer, and separating and dividing the voltage from the main circuit using a high resistance. in any case,
The power supply voltage detection means only needs to be able to detect the presence or absence of the power supply voltage, and it goes without saying that it may have a simple configuration.

〔Effect of the invention〕

As explained above, according to the present invention, even in a switching regulator type power conversion device, by adding a simple detection means consisting of a very small number of components such as a photocoupler, a resistor, and a diode as shown in the embodiment, reset can be performed. Therefore, there is no need to keep the power switch open for a long period of time until the control circuit voltage disappears, and the reset operation can be performed by opening and closing the power switch for a short time. equipment can be provided.

[Brief explanation of the drawing]

FIGS. 1 and 2 are circuit diagrams showing the main part configuration of an embodiment according to the present invention and its power supply voltage detection circuit part, and FIG. 3 is a circuit diagram showing the main part structure of a conventional example. l...i! Source, 2...Power switch, 3
...Forward conversion section, 4...DC smoothing section, 5
...Inverse conversion unit, 7...Switching regulator, 8...Control circuit, 9...
Power supply voltage detection circuit.

Claims (1)

[Claims] In a power conversion device that supplies control circuit power from a DC smoothing section, a power supply voltage detection circuit is provided to detect whether a power switch is open or closed, and the control circuit power supply is reset by the output of the power supply voltage detection circuit. A method for resetting a control circuit of a power conversion device, characterized in that: