JP2003259649A - Control method of self-excited dc power supply - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method for improving the operational reliability of a self-excited DC power supply. <P>SOLUTION: The self-excited DC power supply 4 comprises a control section 40 composed of a pulse generating circuit 41, comparators 42 and 43, and a selector 44. While keeping a relation VH<SB>1</SB>>VH<SB>2</SB>>VH<SB>3</SB>among monitor levels VH<SB>1</SB>, VH<SB>2</SB>and VH<SB>3</SB>at the control section 40 for protecting an IGBT or a diode in a self-excited rectifier circuit 23 forming a main circuit 20 against damage incident to the application of an overvoltage, the monitor levels VH<SB>1</SB>, VH<SB>2</SB>and VH<SB>3</SB>are selected depending on the state of the self-excited DC power supply 4. <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 self-excited DC power supply device which converts the voltage of an AC power supply into a desired DC voltage and supplies it to a load, and regenerates excess DC power from the load to the AC power supply. Control method.

[0002]

2. Description of the Related Art FIG. 3 is a circuit diagram showing a conventional example of this type of self-excited DC power supply device. 1 is an AC power supply such as a commercial power supply, 2 is a self-excited DC power supply device, and 3 is a self-excited DC power supply. It is a load of the power supply device 2.

This self-excited DC power supply 2 is an AC circuit breaker 2.
1, AC reactor 22, self-excited rectifier circuit 23, capacitor 24, DC reactor 25, DC circuit breakers 26, 2
7, a main circuit section 20 of the self-excited DC power supply device including a discharge resistor 28 and a voltage detector 29, and a control section 30 of the self-excited DC power supply device including a pulse generation circuit 31 and a comparator 32.

In the self-excited DC power supply device 2 shown in FIG. 3, self-excited rectification is formed by connecting a self-extinguishing element such as an IGBT (insulated gate bipolar transistor) and an anti-parallel circuit of a diode as shown in the drawing. Circuit 2
A pulse width modulation (PWM) controlled drive signal generated by a well-known technique is applied from the pulse generation circuit 31 to each of the IGBTs forming the circuit 3, thereby changing the voltage of the AC power supply 1 to a desired DC voltage. It is possible to convert the electric power to the load 3 and supply it to the load 3, and at the same time, regenerate the excess DC power from the load 3 to the AC power supply 1.

In the self-excited DC power supply device 2, the voltage across the capacitor 24, that is, the voltage between the output terminals of the self-excited rectifier circuit 23 is detected by the voltage detector 29, and the detected value is detected by the self-excited rectifier circuit 23. The comparator 32 detects this when the monitoring level value V _H0 for preventing damage due to the application of the overvoltage to the above-described self-extinguishing element or diode to be formed is detected, and based on this detection, the self-excited DC While the power supply device 2 is operating, the control operation of the pulse generation circuit 31 is stopped, and the AC circuit breaker 21 and the DC circuit breaker 26 are opened via a sequence circuit (not shown).
By turning on 7, the accumulated charge in the capacitor 24 is discharged through the discharge resistor 28.

The monitoring level value V _H0 at this time is set to about 60% of the rated withstand voltage of the element in consideration of the transient jump-up voltage during the operation of the self-exciting rectifier circuit 23.

[0007]

In the conventional self-excited DC power supply device 2 shown in FIG. 3, when the load 3 is, for example, a DC train with a regenerative function, the self-excited DC power supply device 2 is used.
This DC electric train may perform powering and regenerative operation regardless of the state of, and, in particular, as shown in the operation waveform diagram of FIG. 4, when the self-excited DC power supply device 2 is stopped by an external stop command. When the regenerative operation is performed while waiting, the voltage across the capacitor 24 rises. As shown in FIG. 4, when the increase value exceeds the monitoring level value V _H0 at time t ₁ , the AC breaker 21 and the DC breaker 26 are opened via the sequence circuit.

That is, in order to prevent the voltage across the capacitor 24 from rising due to the regenerative operation from the load 3 when the self-exciting DC power supply 2 is standing by in a stopped state, the self-exciting DC power supply 2 It is necessary to open the DC circuit breaker 26 at all times when the DC circuit breaker is stopped. As a result, a new problem arises that the frequency of making and breaking the DC circuit breaker 26 increases and the life is shortened. To do.

An object of the present invention is to provide a control method for a self-excited DC power supply device which solves the above problems.

[0010]

According to the first aspect of the present invention, the voltage of an AC power supply is converted into a desired DC voltage and supplied to a load, and excess DC power from the load is regenerated to the AC power supply. In a self-excited DC power supply device, a control method characterized by changing a monitoring level value for protecting the power supply device from a DC overvoltage is performed according to the state of the self-excited DC power supply device.

According to a second aspect of the present invention, in the control method for the self-excited DC power supply device according to the first aspect, the monitoring level value V _H1 when the self-excited DC power supply device is stopped and the power supply device are The monitoring level value V when driving
And _H2, between the monitoring level value V _H3 when power supply device shifts to the operation from the stop, characterized in that to have a relationship of _{V H1> V H2> V H3} .

According to the present invention, the operation reliability of the entire power supply device is improved by changing the monitoring level value for protecting the power supply device from the DC overvoltage according to the state of the self-excited DC power supply device. can do.

[0013]

FIG. 1 is a circuit configuration diagram of a self-exciting DC power supply device showing an embodiment of the present invention. Components having the same functions as those of the conventional circuit shown in FIG. The description is omitted here.

That is, the self-excited DC power supply device 4 shown in FIG. 1 is a self-excited DC power supply device including a main circuit section 20 of the self-excited DC power supply device, a pulse generation circuit 41, comparators 42 and 43, and a selector 44. Control unit 40 of each of the IGBTs forming the self-excited rectifier circuit 23,
A PWM-controlled drive signal generated by a well-known technique is supplied from the pulse generation circuit 41 forming the control unit 40, thereby converting the voltage of the AC power supply 1 into a desired DC voltage and supplying the same to the load 3. The excess DC power from the load 3 can be regenerated to the AC power supply 1.

Further, the control unit 40 changes the monitoring level value for the detection value of the voltage detector 29 according to the state of the self-exciting DC power supply device 4.

That is, in order to prevent the damage of the self-exciting rectifier circuit 23 constituting the main circuit 20 due to the overvoltage application to the IGBT and the diode, the monitoring level value V _H1 when the self-exciting DC power supply device 4 is stopped. And a monitoring level value V _H2 when the self-excited DC power supply device 4 is operating, and a monitoring level value V _H3 when the self-excitation DC power supply device 4 shifts from stop to operation. In the meantime, as described below, V _H1
> V _H2 > V _H3 .

The relationship between each of the monitoring level values V _H1 , V _H2 and V _H3 and the self-excited DC power supply device 4 will be described below with reference to the operation waveform diagram shown in FIG.

First, when the pulse generation circuit 41 is stopping the above control operation, the selector 44 causes the IGBT to operate.
And a monitoring level value V _H1 set to, for example, about 90% of the rated withstand voltage of the diode, is output, and when the pulse generation circuit 41 is performing the control operation described above,
The selector 44 selects and outputs the monitoring level value V _H2 set to, for example, about 60% of the rated withstand voltage of the element.

When an operation command is externally issued to the pulse generation circuit 41 at time t ₁ , as shown in FIG. 2, at this time, the voltage across the capacitor 24 is lower than the monitoring level value V _H1 and the rating of the element is satisfied. Since the both-end voltage is lower than the monitoring level value V _H3 set to, for example, about 50% of the withstand voltage, each of the comparators 42 and 43 outputs an operation permission signal, and as a result, the pulse generation circuit 41 causes At the same time as starting the control operation, the selector 44 is instructed to select and output the monitoring level value V _H2 . Even when this command is issued, as shown in FIG. 2, the monitoring level value V
Since the voltage across capacitor 24 is lower than _H2 , comparator 4
2 continues to output the operation permission signal.

Next, when a stop command is externally issued to the pulse generating circuit 41 at time t ₂ , the pulse generating circuit 41 immediately stops the above-mentioned control operation, and the selector 44 _{sets the} monitoring level value V _H1 . Send a command to select and output.

The self-excited DC power supply device 4 after the time t ₂
2, the voltage across the capacitor 24 is changed to the monitoring level value V by the regenerative operation from the load 3 as shown in FIG.
_{When H1} is exceeded, the comparator 42 detects this, and the AC circuit breaker 21 and the DC circuit breaker 2 are connected via a sequence circuit (not shown).
By opening 6 and 6 and further turning on the DC breaker 27, the charge accumulated in the capacitor 24 is discharged through the discharge resistor 28.

At time t ₃ , an operation command is again issued from outside to the pulse generating circuit 41. At this time, as shown in FIG. 2, due to the regenerative operation from the load 3 until immediately before time t ₃ , the voltage across the capacitor 24 is changed. The monitoring level value V _H3
Therefore, the comparator 43 outputs the operation stop signal and the comparator 42 outputs the operation enable signal. Therefore, the pulse generation circuit 41 continues the above-mentioned control operation stopped state. To do.

Next, at time t ₄ when the self-exciting DC power supply device 4 is stopped, as shown in FIG. 2, the power running operation of the load 3 immediately before time t ₄ causes the voltage across the capacitor 24 to reach the monitoring level value. When it becomes lower than V _H3, the output of the comparator 43 is switched from the operation stop signal to the operation permission signal, and as a result, the pulse generation circuit 41 starts the above-mentioned control operation and at the same time, the selector 44 outputs the monitoring level value V _H2 . A command to select and output is issued. Even when this command is issued, since the voltage across the capacitor 24 is lower than the monitoring level value V _H2 , the comparator 42 continues to output the operation permission signal.

[0024] In addition, the self-excited after the time t ₄ direct-current power supply 4
During operation, the capacitor 24
When the voltage across both ends of the pulse voltage exceeds the monitoring level value V _H2 , the comparator 42 detects this and stops the control operation of the pulse generation circuit 41 based on this detection, and the AC circuit breaker 21 via the sequence circuit. And the DC breaker 26 are opened, and then the DC breaker 27 is turned on,
The electric charge accumulated in the capacitor 24 is discharged through the discharge resistor 28.

As described above, in order to prevent the damage of the self-excited rectifier circuit 23 constituting the main circuit 20 due to the overvoltage application to the IGBT and the diode, the self-excited DC power supply device 4 is stopped. By setting the monitoring level value V _H1 as high as possible at about 90% of the rated withstand voltage of the element, the frequency of making and breaking the DC breaker 26 can be suppressed. Further, the monitoring level value V _H2 when the self-excited DC power supply device 4 is operating is 60% of the rated withstand voltage of the element in consideration of the transient jump-up voltage during the operation of the self-excited rectifier circuit 23. The value is set to be about the same, and this value is set to be substantially the same as the monitoring level value V _H0 in the conventional circuit shown in FIG. Further, the monitoring level value V _H3 when the self-exciting DC power supply device 4 shifts from stop to operation is set to about 50% of the rated withstand voltage of the element because the transient jump-up voltage does not occur. By doing so, the current stress on the element immediately after the self-excited rectifier circuit 23 starts operating can be reduced, and as a result, the self-excited DC power supply device 4
The operational reliability of can be improved.

[0026]

According to the present invention, according to the state of the self-exciting DC power supply device, the monitoring level value for protecting the power supply device from the DC overvoltage is changed, so that the DC cutoff constituting the power supply device is cut off. It is possible to reduce the frequency of turning on and off the equipment, and to start the power supply more safely when the power supply device shifts from stop to operation, and as a result, without increasing the price of the main circuit part of the power supply device, It is possible to provide a self-excited DC power supply device having high operation reliability as a whole.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of a self-excited DC power supply device showing an embodiment of the present invention.

FIG. 2 is a waveform diagram illustrating the operation of FIG.

FIG. 3 is a circuit configuration diagram of a self-excited DC power supply device showing a conventional example.

FIG. 4 is a waveform diagram illustrating the operation of FIG.

[Explanation of symbols]

1 ... AC power supply, 2 ... Self-exciting DC power supply device, 3 ... Load, 4
... Self-excited DC power supply, 20 ... Main circuit part of self-excited DC power supply, 21 ... AC breaker, 22 ... AC reactor, 2
3 ... Self-excited rectifier circuit, 24 ... Capacitor, 25 ... DC reactor, 26, 27 ... DC circuit breaker, 28 ... Discharge resistance,
29 ... Voltage detector, 30 ... Self-excited DC power supply control unit, 31 ... Pulse generation circuit, 32 ... Comparator, 40 ... Self-excitation DC power supply control unit, 41 ... Pulse generation circuit, 4
2, 43 ... Comparator, 44 ... Selector.

Continued front page    (72) Inventor Kenji Baba             1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa             Fuji Electric shares F-term (reference) 5H006 AA05 CA01 CA07 CB01 CB08                       DC05 FA01

Claims (2)

[Claims] 1. A self-excited DC power supply device for converting the voltage of an AC power supply into a desired DC voltage and supplying it to a load, and for regenerating the excess DC power from this load to the AC power supply. A method of controlling a self-excited DC power supply, comprising changing a monitoring level value for protecting the power supply from a DC overvoltage according to the state of the power supply. 2. The control method for the self-excited DC power supply device according to claim 1, wherein the monitoring level value V _H1 when the self-excited DC power supply device is stopped, and the power supply device are operating. V _H1 > V _H2 between the monitoring level value V _H2 at this time and the monitoring level value V _H3 when the power supply device shifts from stop to operation.
A control method for a self-excited DC power supply device, characterized in that a relation of> V _H3 is provided.