JP2003199349A - Power converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power converter which can extend the output voltage control range thereof to a value which is not higher than a crest value of an AC input voltage and can operate, regardless of the value of a DC voltage. <P>SOLUTION: This power converter comprises a PWM converter which has an inversion circuit 1 comprising self-extinguishing devices 3 and a rectifying circuit 2 comprising controllable devices 4, which are rectifying devices and is composed of a parallel circuit of the inverting circuit 1 and the rectifying circuit 2. If the targeted value of the DC output voltage is not higher than the crest value of an AC input voltage, only rectifying circuit gate signals 7 are supplied, and the DC output voltage is controlled by the phase control. If the target value exceeds the crest value, rectifying circuit gate signals 7 are made to be always in ON-states and the controllable devices 4 are made to function in the same way as freewheel diodes. As a result of such a constitution, the power converter can operate, regardless of the value of the DC voltage. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter in which the application range of a PWM converter is expanded.

[0002]

2. Description of the Related Art FIG. 7 shows the configuration of a conventional power converter including a PWM converter. As shown in the figure, this power conversion device is configured by using a PWM circuit 1'comprising a self-extinguishing element 3 and a freewheel diode 5'which is an uncontrollable element connected in antiparallel. There is. Current limiting resistor 1 to suppress rush current when DC voltage is low
A circuit for inserting 5 is provided, and the circuit switching device 1
4, the circuit is switched at the time of starting and restarting after the momentary power failure.

[0003]

In the prior art, the DC output voltage cannot be controlled below the peak value of the AC input voltage due to the presence of the uncontrollable element 5'connected in antiparallel. Further, when the DC voltage is low such as at the time of starting and restarting after the momentary power failure, it is necessary to insert the current limiting resistor 15 and wait for the rise of the DC voltage, so that quick startup is impossible. Furthermore, since it does not have the ability to interrupt the current when a short circuit occurs on the AC input side or the DC output side, it is not possible to load the load with a protection circuit by an AC power supply short circuit event or a crowbar switch due to damage to the self-extinguishing element 3. There was a problem that we could not respond.

The present invention has been made in order to solve the above problems. The output voltage control range is expanded to a peak value of the AC input voltage or less, and operation is possible regardless of the DC voltage value.
It is an object of the present invention to provide a power conversion device that can handle AC input short circuit and crowbar switch load.

[0005]

In order to achieve the above object, the present invention provides a PWM in which a reverse conversion circuit composed of a self-turn-off device and a rectification circuit composed of a rectifying device are connected in parallel.
In the power conversion device including a converter, the rectifying element is a controllable element.

According to the present invention, the output voltage control range can be expanded to the peak value of the AC input voltage or less without increasing the number of circuit elements, and the operation can be performed regardless of the value of the DC voltage.

Further, the present invention is a power converter comprising a PWM converter in which an inverse conversion circuit composed of a self-extinguishing type element and a rectification circuit composed of a rectifying element are connected in parallel. The element on the side is a controllable element.

According to the present invention, the output voltage control range is expanded to the peak value of the AC input voltage or less without increasing the number of elements of the circuit, the operation can be performed regardless of the value of the DC voltage, and the rectifier circuit is provided. It is possible to halve the number of signals supplied to the device and simplify the device configuration.

[0009]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. In the following figures, the same reference numerals indicate the same parts or corresponding parts.

(First Embodiment) FIG. 1 shows the configuration of a power conversion device according to a first embodiment of the present invention. As shown in the figure, this embodiment is composed of a PWM converter in which a reverse conversion circuit 1 composed of a self-arc-extinguishing element 3 and a rectification circuit 2 composed of a controllable element 4 as a rectifying element are connected in parallel. The PWM gate signal 6 and the rectifier circuit gate signal 7 output from the gate signal generation circuit 20 when the device is stopped
Both are dormant. Since the controllable element 4 is provided in the electric path from the AC input to the DC output, the DC output voltage can be maintained at zero even when the AC input is applied.

Next, in the operating state of the apparatus, the operation differs depending on whether the target value of the DC output voltage exceeds the peak value of the AC input voltage. When the target value of the DC output voltage is less than or equal to the peak value of the AC input voltage, the gate signal generation circuit 20 supplies only the rectifier circuit gate signal 7, and the controllable element 4 of the rectifier circuit 2 is operated to perform the phase angle control operation. Control the output voltage. When the target value of the DC output voltage exceeds the peak value of the AC input voltage, the gate signal generation circuit 20 supplies the PWM gate signal 6 according to the target value of the DC output voltage, and the rectifier circuit gate signal 7 is always supplied. By supplying the controllable element 4 as ON, the controllable element 4 functions similarly to the freewheel diode 5 ′ in the normal PWM converter.

According to the present embodiment, the DC output voltage can be controlled to an arbitrary value below the peak value of the AC input voltage without increasing the number of circuit elements. Further, the circuit switch 14 and the current limiting resistor 15 in the conventional configuration are not necessary, and the waiting time until the capacitor of the output section is charged via the current limiting resistor 15 is also unnecessary.

(Second Embodiment) The configuration of a power conversion device according to a second embodiment of the present invention is shown in FIGS. 2 (a) and 2 (b). The difference from FIG. 1 is that, as shown in FIG. 2B or FIG. 2A, the controllable element 4 on the positive or negative side of the rectifier circuit 2 is replaced with the non-controllable element 5. That is. When the target value of the DC output voltage is equal to or lower than the peak value of the AC input voltage, the DC output voltage is controlled by operating the controllable element 4 on one of the positive side and the negative side. As a result, the number of points of the rectifier circuit gate signal 7 is halved, and the device configuration can be simplified.

(Third Embodiment) FIG. 3 shows the configuration of a power conversion device according to a third embodiment of the present invention. The difference from FIG. 1 is the presence of an AC voltage drop detector 8 that detects a drop in the AC input voltage and a DC voltage drop detector 9 that detects a drop in the DC output voltage. When the AC input voltage drops due to a system fault or the like, the gate signal generation circuit 20 stops the supply of the PWM gate signal 6 and the rectifier circuit gate signal 7 by the detection signal of the AC voltage drop detector 8 that detects this. Next, when the AC input voltage is restored and the signal of the AC voltage drop detector 8 is restored, the gate signal generation circuit 20 supplies only the rectifier circuit gate signal 7 while the detection signal of the DC voltage drop detector 9 is present. The DC output voltage is controlled by operating the controllable element 4 of the rectifier circuit 2 in a phase angle control operation. When the signal from the DC voltage drop detector 9 returns, the gate signal generation circuit supplies the PWM gate signal 6 in accordance with the target value of the DC output voltage, and the rectifier circuit gate signal 7 is always on, so that control is possible. The element 4 is made to function like the freewheel diode 5'in a normal PWM converter.

According to the present embodiment, when recovering from a transient event such as the occurrence of a power failure and the accompanying drop in the DC output voltage, the waiting time until the capacitor of the output section is charged via the current limiting resistor 15 becomes unnecessary, The device can be restarted quickly.

(Fourth Embodiment) FIGS. 4A and 4B show the configuration of a power conversion device according to a fourth embodiment of the present invention. The difference from FIG. 3 is that, as shown in FIG. 4B or FIG. 4A, the controllable element 4 on the positive or negative side of the rectifier circuit 2 is replaced with the non-controllable element 5. That is. When the target value of the DC output voltage is equal to or lower than the peak value of the AC input voltage, the DC output voltage is controlled by operating the controllable element 4 on one of the positive side and the negative side. As a result, the number of points of the rectifier circuit gate signal 7 is halved, and the device configuration can be simplified.

(Fifth Embodiment) FIG. 5 shows the configuration of a power conversion device according to a fifth embodiment of the present invention. The difference from FIG. 1 is that a DC voltage drop detector 9 for detecting a DC voltage drop, a load inverter 10, a current detector 11, a DC overcurrent detector 12 for detecting a DC overcurrent, and a crowbar switch 1 are provided.
There are three. When an overcurrent flows in the DC portion, the DC overcurrent detector 12 detects this and outputs a signal, and operates the crowbar switch 13 to shunt the current flowing into the load inverter 10. DC overcurrent detector 12 at the same time
Instructs the gate signal generation circuit 20 to stop the PWM gate signal 6 and the rectifier circuit gate signal 7 and cut off the inflow of current from the AC side. Next, when the crowbar switch 13 returns, while the detection signal of the DC voltage drop detector 9 is present, the gate signal generation circuit 20 supplies only the rectifier circuit gate signal 7, and the controllable element 4 of the rectifier circuit 2 is phased. The DC output voltage is controlled by operating the angle control. When the signal from the DC voltage drop detector 9 returns, the gate signal generation circuit 20 supplies the PWM gate signal 6 in accordance with the target value of the DC output voltage, and the rectifier circuit gate signal 7 is always on, thereby enabling the operation. The control element 4 functions as a freewheel diode 5'in a normal PWM converter.

According to the present embodiment, it is possible to apply the PWM converter to the load provided with the crowbar switch.

(Sixth Embodiment) The configuration of a power conversion device according to a sixth embodiment of the present invention is shown in FIGS. 6 (a) and 6 (b). The difference from FIG. 5 is that, as shown in FIG. 6B or 6A, the controllable element 4 on the positive side or the negative side of the rectifier circuit 2 is replaced with the non-controllable element 5. Is. When the target value of the DC output voltage is equal to or lower than the peak value of the AC input voltage, the DC output voltage is controlled by operating the controllable element 4 on one of the positive side and the negative side. As a result, the number of points of the rectifier circuit gate signal 7 is halved, and the device configuration can be simplified.

[0020]

As described above, according to the present invention, the output voltage control range is expanded to the peak value of the AC input voltage or less,
It is possible to realize a power conversion device that can be operated regardless of the value of the DC voltage and that can also handle AC input short circuits and crowbar switch loads.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a power conversion device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a power conversion device according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a power conversion device according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram of a power conversion device according to a fourth embodiment of the present invention.

FIG. 5 is a configuration diagram of a power conversion device according to a fifth embodiment of the present invention.

FIG. 6 is a configuration diagram of a power conversion device according to a sixth embodiment of the present invention.

FIG. 7 is a configuration diagram of a conventional power conversion device.

[Explanation of symbols]

1 ... Inverse conversion circuit 2 ... Rectifier circuit 3 self-extinguishing element 4 ... Controllable element 5: Non-controllable element 6 ... PWM gate signal 7 ... Rectifier circuit gate signal 8 ... AC voltage drop detection circuit 9 ... DC voltage drop detection circuit 10 ... Load inverter 11 ... Current detector 12 ... DC overcurrent detector 13 ... Clover switch 14 ... Circuit changer 15 ... Current limiting resistance 20 ... Gate signal generation circuit

Claims (4)

[Claims] 1. A power converter comprising a PWM converter in which a reverse conversion circuit composed of self-extinguishing elements and a rectification circuit composed of rectification elements are connected in parallel, wherein the rectification element is a controllable element. A power conversion device characterized by: 2. A power converter comprising a PWM converter in which a reverse conversion circuit composed of a self-extinguishing element and a rectification circuit composed of a rectifying element are connected in parallel, and a positive or negative element of the rectification circuit. Is a controllable element. 3. The power converter according to claim 1 or 2, wherein the first means for detecting a decrease in the AC input voltage, the second means for detecting a decrease in the DC output voltage, and the second means. When neither the first means nor the second means are operating, the inverse conversion circuit is activated and the rectifier circuit is always turned on. When the first means is operating, Both the inverse conversion circuit and the rectification circuit are stopped, and when the first means is not operating and only the second means is operating, the inverse conversion circuit is stopped and the rectification circuit is phase-controlled. A third means for switching to operate the power converter. 4. The power converter according to claim 1 or 2, wherein a load inverter connected to the DC output side, a second means for detecting a decrease in the DC voltage, and an overcurrent in the DC section. The fourth means for detecting, the fifth means for short-circuiting the DC circuit by the signal of the fourth means, the reverse means when neither the second means nor the fifth means are operating. The control circuit of the rectification circuit is always turned on while the conversion circuit is in an operating state, and both the inverse conversion circuit and the rectification circuit are stopped when the fifth means is operating, and the fifth circuit is operated. And a sixth means for switching the controllable element of the rectifier circuit so as to perform the phase control operation when the inverse conversion circuit is stopped and only the second means is operating. A power conversion device characterized by: