JP2836458B2 - DC chopper device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC chopper for converting a certain DC power into another DC power. More specifically, the present invention relates to a DC chopper device which is built in a self-excited conversion circuit using a self-extinguishing type device and returns the energy absorbed by a snubber capacitor of the self-excited conversion circuit to the DC side.

[0002]

2. Description of the Related Art FIG. 8 shows the energy absorbed by a snubber capacitor of a self-excited conversion circuit using a self-extinguishing device shown in "Semiconductor Power Conversion Circuit" published by the Institute of Electrical Engineers of Japan in March 1987. FIG. 9 is a block diagram showing the configuration of a conventional DC chopper circuit returning to the DC side, FIG. 9 is a block diagram of a self-excited conversion circuit for explaining the configuration of the constant current source shown in FIG. 8, and FIG. 10 is the DC chopper shown in FIG. 6 is a timing chart illustrating an operation of the circuit.

In FIG. 1, reference numeral 11 denotes a self-extinguishing type semiconductor switch such as a GTO, 12 denotes a return diode for returning a reactor current when the semiconductor switch 11 is turned off, 13 denotes a DC reactor for current smoothing, and 14 denotes a description. A constant current source indicating an input power supply, 15 a DC capacitor for reducing the input of the semiconductor switch 1 to a low impedance, 16 a constant voltage source for indicating an output side power for explanation, and 17 a DC voltage detecting means for detecting the voltage E _c, current detecting means for detecting a DC current I _L 18, 19 is a semiconductor switch driving circuit for controlling the semiconductor switch 11, a DC chopper 19 from 11 The main circuit 1 of the device is constituted. 21
DC voltage setting means for outputting a setting voltage E _c of the DC capacitor 15 ^*, 22 an adder for detecting a set voltage E _c ^* deviation between the DC voltage E _c, 23 based on the output of the adder 22 voltage control means for controlling the DC voltage of the capacitor 15, 24 is an adder for adding the output I _L ^* of the output I _L and the voltage control means 23 of the current detecting means 18, 25 based on the output of the adder 24 current control means for outputting a signal V _chp for controlling the current I _L of the DC reactor 13, 2
6 is a carrier generation means for outputting a triangular wave signal V _osc for controlling the ON / OFF cycle of the semiconductor switch 11, 27 is an adder for adding the signal V _chp and the signal V _osc , and 28 is a signal based on the output of the adder 27 This is a comparator for comparing V _chp with the signal V _osc , and its output acts on the semiconductor switch 11 via the semiconductor switch driving circuit 19. 21 to 28 constitute the control circuit 2 of the DC chopper device.

Next, the operation will be described. In FIG. 8, the output E _out of the semiconductor switch 11 becomes equal to the input voltage E _c during the period T _on when the semiconductor switch 11 is conducting, and the return diode 12 is conducting during the period T _off when the semiconductor switch 11 is not conducting. As a result, the voltage E _out becomes zero. Since this voltage is smoothed by the DC reactor 13, the input voltage E
relationship _c and the output voltage E _d is expressed by the following equation. E _d = E _c × T _on / (T _on + T _off ) Equation 1 or E _c = E _d × (T _on + T _off ) / T _on Equation 2 where α = T _on / (T _on + T _off ) Equation 3 Is referred to as the conductivity α of the semiconductor switch.

[0005] For example when the output voltage E _d is constant, the voltage E _c of the DC capacitor charged by the constant current source 14 can be controlled to a constant value by controlling the conduction rate alpha.
For the control of the DC voltage E _c, is provided voltage determining means 21 and the voltage control means 23 for setting the DC voltage E _c,
It is controlled to be an input voltage E _c obtained as the output of the voltage detecting means 17 constant. Output I of voltage control means 23
_L ^* acts on the current control means 25, the current I _L a DC voltage E _c of the DC reactor 13, which is obtained as the output of the current detecting means 18 is controlled to be constant. That is, the output V _chp of the current control unit 25 corresponds to the conductivity α. The output V _chp of the current control means 25 is compared with the output of the carrier generation means 26 by the comparator 28 and the output V _chp of the semiconductor switch 11 is
As an N / OFF signal, it acts on the semiconductor switch 11 via the drive circuit 19. Used in the above description,
The constant current power supply 14 indicating the input power supply will be described in detail. FIG. 9 is a block diagram showing a configuration of a self-excited conversion circuit using a conventional self-extinguishing device shown in the above-mentioned document "Semiconductor power conversion circuit". This figure shows only one phase extracted from the three-phase AC circuit. In the figure, 51a and 51b are self-extinguishing type conversion circuit semiconductor switches made of, for example, GTO, and 52a,
52b is a conversion circuit feedback diode, 53a and 53b are conversion circuit reactors, 54a and 54b are snubber diodes, 55a and 55b are snubber capacitors, 56a and 5b.
6b is a diode, 57 is a converter DC power supply, 58 is a converter AC output terminal, 59a and 59b are regenerative power output terminals connected to the DC chopper device 1, and 60 is a converter that determines the output voltage of the self-excited converter 5. The circuit output voltage commanding means 61 is also a conversion circuit carrier wave generating means for generating a signal for determining the switching cycle of the self-excited conversion circuit 5, and 6
2 is an adder, 63 is a comparison means, 64a and 64b are conversion circuit driving means for insulating and amplifying a signal to drive the semiconductor switches 56a and 56b, and the self-excited conversion circuit 5 is constituted by 51 to 64. Regenerative power output terminal 59
a and 59b are DC chopper device main circuits 1 in FIG.
Of the constant current source 14 of FIG.

Next, the operation will be described. In the figure, the output of the conversion circuit output voltage command means 60 and the output of the conversion circuit carrier generation means 61 are compared by the comparison means 63, and the conversion circuit semiconductor switches 56a and 56b are turned ON / OFF according to the polarity.
A so-called PWM control is performed. In this type of device, the reactance of the conversion circuit reactors 53a, 53b is relatively large, and the conversion circuit semiconductor switches 51a, 51b
With the ON / OFF of b, the conversion circuit reactor 53a,
The problem is how to process the energy stored in 53b. Usually this energy is a snubber diode 5
4a, 54b, snubber capacitors 55a, 55b.
b, and then guided to regenerative power output terminals 59a, 59b via diodes 56a, 56b. The regenerative power output terminals 59a and 59b are the detailed configuration of the constant current power supply 4 of the DC chopper main circuit 1 in FIG.

[0007]

The DC chopper device built in the conventional self-excited conversion circuit is configured as described above, and operates as shown in the timing chart of FIG. In some cases, such a problem may occur, and for this measure, the capacity of the DC capacitor 15 needs to be sufficiently increased, and the device becomes uneconomical. Failure 1 In the time chart of FIG. 10, at time t ₁ , for example, the output frequency of the conversion circuit carrier generation means 61 changes stepwise on the self-excited conversion circuit 5 side, and as a result, the constant current power supply 1
When the input current I _in from step 4 increases stepwise, the regenerative current also needs to change abruptly according to this change.
In practice, however (1) Output I _L ^* increases (5) current control of the input current I _in increases (2) DC voltage E _c increases (3) deviation occurs between the DC voltage reference E _c (4) voltage control means 23 The output V _{chp of the} means 25 is increased. (6) The conductivity α is increased. (7) The regenerative current I _{L is} increased. The control is repeated until the DC voltage E _c becomes equal to the DC voltage reference value. large, jump large between the DC voltage E _c. In order to suppress this, the DC capacitor 15 has a larger capacity or a higher withstand voltage, and further, the switching frequency of the semiconductor switch 11 has been increased in order to increase the response of the control system. As a result, disadvantages such as an increase in the loss of the semiconductor switch 11 occur.

[0008] In the time chart of defect 2 10, when the input current I _in from the constant current source 14 has dropped stepwise at time t _2, the which the regenerative current I _L the conduction ratio α slightly larger to It is necessary to suppress in accordance with. However, in practice, as in the case of the first problem, a delay proportional to the response time of the control system occurs until the output I _L ^* of the voltage control means 23 decreases _in accordance with the input current I _in , so that the DC voltage E _c is greatly reduced. To suppress this, the DC capacitor is increased in capacity, or the semiconductor switch 11 is made to have a higher withstand voltage. Further, the switching frequency of the semiconductor switch 11 is increased in order to increase the response of the control system. ing. As a result, disadvantages such as an increase in the loss of the semiconductor switch 11 occur.

[0009]

The DC chopper device according to the present invention is used in combination with a self-excited conversion circuit using a self-extinguishing device, and the switching frequency of the self-excited conversion circuit changes or the current is reduced. Even when the snubber energy to be regenerated due to the change is changed, means for compensating the voltage control signal or the current control signal is provided so as to match the change.

[0010]

The DC chopper device according to the present invention is provided with regenerative power compensating means, and its output is input to the current control means or voltage control means of the DC chopper device, so that the current control is performed even when the chopper frequency or the regenerative current changes suddenly. The reference signal from the means is changed quickly so as to match the change in regenerative energy.

[0011]

【Example】

Embodiment 1 FIG. The present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an embodiment of a DC chopper device according to the present invention, FIG. 2 is a block diagram showing a configuration of operating state compensating means, and FIGS. 3 and 4 are blocks showing modified examples of operating state compensating means. FIGS. 6, 6 and 7 are timing charts showing the operation of the DC chopper device shown in FIG. In the drawing, the same or corresponding parts as those in the above-described conventional example are denoted by the same reference numerals, and description thereof will be omitted unless otherwise required.

1 and 2A, reference numeral 29 denotes regenerative power compensating means, 30 denotes input current detecting means, 31 denotes operating state compensating means, and 32 denotes an adder. Reference numeral 33a denotes a frequency / voltage converter, which converts the output of the comparing means 63 in the conversion circuit 5 into a voltage / voltage and outputs a DC voltage proportional to the switching frequency of the conversion circuit 5. 33b is a coefficient unit, 33c is a contact that closes during the operation of the conversion circuit 5, and 33a, 33b and 33c constitute a conversion circuit switching frequency compensation means 33. Further, reference numeral 34a denotes a voltage divider formed of a variable resistor, and 34b denotes a contact which closes during the operation of the conversion circuit 5, similarly to 33c. The start compensating means 33 is constituted by 34a and 34b. An adder 35 constitutes the operating state compensating means 31 with 33, 34 and 35.

Next, the operation will be described. First, the main circuit 1 and the control circuit 2 of the DC chopper device, description will be given of a case where only the input current I _L has changed for some reason. Assuming that the input current I _in has changed abruptly at a certain time, a signal from the input current detection means 30 is added to the input of the current control means 23 at this time as a regenerative power compensation signal. That is, the input current I _in is changing rapidly, even after changing the current of the DC chopper device, since the current command of the current control means changes commensurate with this, commensurate with the input current I _in the reactor current I _L Can flow. Thus, DC voltage E _c fluctuation is suppressed, as a result, as compared to conventional DC chopper device, more compact and economical,
An apparatus having excellent responsiveness can be realized.

As described above, even if the input current I _in changes abruptly and the current of the DC chopper device also changes abruptly, the reactor current I _L ^{* as} shown in FIG.
Because of changes slowly varying commensurate with a change in the output I _L of the voltage control means 22 can not reactor current I _L flows commensurate with the input current I _in, as a result, the DC voltage E _c is large variation Although it was then, in the present invention, the regenerative power compensation signal commensurate with the input current I _in from the regenerative power compensation means 29 is provided, as in the prior art problem does not occur.

Next, a case where the frequency of the main circuit carrier generation means 61 of the conversion circuit 5 changes for some reason will be described. In the timing chart 6 in this case, the frequency of the converter carrier generator means 61 at time t ₁ has increased for example stepwise. At this time, the signal from the switching frequency compensator 33 is added to the input of the current controller 23 in a stepwise manner as a regenerative power compensation signal. In other words, even if the frequency of the conversion circuit carrier generation means 61 changes stepwise and the regenerative power of the DC chopper device changes abruptly, the current command of the current control means changes stepwise in accordance with this. I _L can also flow according to the regenerative power that is substantially proportional to the frequency of the main circuit carrier generation means 61. Therefore, the DC voltage E _c
The fluctuation is also suppressed. Also, during a period during which the output voltage command is larger than the carrier wave, such as between times t ₂ and t _3, the output of the frequency / voltage converter also disappears at the same time as the regenerative power is lost, so that the change in the regenerative power causes The current command changes accordingly. As a result, it is possible to realize a device that is more compact, more economical, and more responsive than a conventional DC chopper device.

As described above, even if the switching frequency of the conversion circuit semiconductor switch changes stepwise, the regenerative power almost proportional to this frequency changes stepwise, and even if the current of the DC chopper device changes abruptly, the conventional switching frequency changes. If it is a device,
Reactor current I _L ^* changes as shown in FIG. 8 for slowly varying commensurate with a change in the output I _L of the voltage control means 22 can not reactor current I _L flows commensurate with the input current I _in as a result, although a DC voltage E _c had fluctuates greatly, according to the present invention, since regenerative power compensation signal from the regenerative power compensation means 29 commensurate with the switching frequency changes in converter semiconductor switch is provided in steps However, the conventional disadvantage does not occur.

In the above description, the case where the frequency of the conversion circuit carrier generation means 61 changes stepwise has been described, but it goes without saying that the same operation can be obtained even when the frequency continuously changes. Since the energy absorbed by the snubber circuit of the self-excited conversion circuit is proportional to the current flowing in the main circuit of the self-excited conversion circuit, the main circuit current of the self-excited conversion circuit is detected, and the above-described frequency / voltage converter is used. Is multiplied by a well-known multiplying means, and this is used as a new conversion circuit switching frequency compensation signal, whereby there is an advantage that more accurate compensation can be performed.

Further, an advantage that is avoided that the DC voltage E _c for the current control means 25 outputs the even chopper device at the time of startup of the self-commutated converter can respond quickly varies greatly. When the self-excited conversion circuit 5 is activated, the activation compensation signal set in advance based on the predicted value is supplied from the activation compensation circuit 34.
The output of the current control means 25 of the chopper device can respond instantaneously. FIG. 7A is a timing chart showing the operation by the operation of the startup compensation circuit 34 alone. Here, by adding the differentiating circuit 36 to the start-up compensation circuit 34 and configuring as shown in FIG. 2B, the start-up compensation signal operates at the start-up as in the case where the start-up compensation circuit 34 is provided alone. The advantage is that the condition is not affected at all. FIG. 7B shows a timing chart in this case.

In the above description, the regenerative power compensating means is a load current detecting means, a conversion circuit switching frequency compensating means,
Although it is assumed that the load compensating means is constituted by the starting compensating means, as is clear from the description of the operation, the load current detecting means, the conversion circuit switching frequency compensating means, and the starting compensating means may be used alone or may be set to any two. By using the two elements in combination, it is possible to solve the problem in the conventional chopper device. What combination is used may be appropriately selected depending on the load condition of the self-excited conversion circuit 5 and the like.

FIGS. 3 and 4 show modified examples of the regenerative power compensating means. FIG. 3 shows a first modification of the regenerative power compensating means according to the present invention. In FIG. 1, the output of the load current detecting means 30 is added to the operation state compensating means and the current controlling means 25
However, here, it is provided to the voltage control means 23. The operation in this case is the same as that in FIG. 1 and has the same effect. The current I _L another effect that suppresses be less likely to over-current at the upper limit value of the voltage control means 22 of the DC chopper device current command and the corresponding order of the output of the voltage control means 23 in this modification is a DC chopper There is. Although the output of the regenerative power compensator 29 is applied to the adder 24 in FIG. 1, it goes without saying that the signals of the respective elements of the regenerative power compensator 29 can be applied to the adder 22 individually or all.

FIG. 4 shows a second modification of the regenerative power compensating means according to the present invention. In the voltage control means 23, each output signal from the voltage detecting means 17, the voltage setting means 21, and the start-up compensation circuit 34 is appropriate. High impedance 23 ₂ , 23 ₃ , 2
Is connected by 3 _4, it is constituted with an operational amplifier 23 ₁ having an impedance 23 ₅ in the feedback circuit. It should be noted that only portions different from FIG. 1 are extracted and shown. Impedance 23 ₄ and 23 ₅ may be usually the same constant. The operation in this case is the same as that in FIG.

Embodiment 2 FIG. FIG. 5 shows a second embodiment of the voltage control circuit of the DC chopper device according to the present invention, in which only differences from FIG. 1 are extracted. 14 ₁ and 14 _{2 in the} figure
‥‥‥ 14 _n is a constant current source composed of n snubber circuits of a self-excited conversion circuit, and 29 ₁ , 29 ₂ ‥‥‥ 29 _n is n constant current sources 14 ₁ , 14 ₂ ‥‥‥ 14 _n Fig. 4 shows n connected regenerative power compensation means.

Next, the operation will be described. In a conventional device, at least n DC chopper devices are provided for snubber energy regeneration of n self-excited conversion circuits.
In this embodiment, at least one DC chopper device is provided for snubber energy regeneration of n self-excited conversion circuits, and n regenerative power compensators 29 ₁ and 29 _{2 are provided.}
‥‥‥ was guided to the input of the current control means 23 adds the output of the 29 _n. Therefore, n self-excited conversion circuits 5
Even if the respective operation modes change, the regenerative power compensating means gives a regenerative input compensation signal for compensating the change of the input current of the DC chopper device to the input of the current control means. together are suppressed fluctuation of flow DC voltage E _c commensurate to I _in, the number of DC chopper device can be reduced, it is possible to provide a device which is excellent in economical efficiency. In this case, the first embodiment
Needless to say, as in the first modified example of the regenerative power compensating means in the first embodiment, the signal of each element of the regenerative power compensating means 29 can be added to the adder 22 individually or all.

[0024]

The DC chopper device according to the present invention comprises:
Even when the switching frequency of the self-excited conversion circuit changes, or when the snubber energy to be regenerated due to a change in current changes, a means for compensating the voltage control signal or the current control signal is provided to match the change.
Even if the regenerative power changes, there is no time delay in the output of the voltage control means or current control means, making it possible to make the capacity of the DC capacitor and the withstand voltage of the semiconductor switch appropriate for the regenerative power. As compared with the conventional DC chopper device, it is possible to realize a chopper device which is smaller in size and has both excellent economy and responsiveness.

[Brief description of the drawings]

FIG. 1 is a block diagram of a DC chopper device according to a first embodiment of the present invention.

FIG. 2 is a block diagram of an operation state compensating means of the present invention.

FIG. 3 is a block diagram of a first modification of the operating state compensating means of the present invention.

FIG. 4 is a block diagram of a second modification of the operating state compensating means of the present invention.

FIG. 5 is a block diagram of a second embodiment of the DC chopper device according to the present invention.

FIG. 6 is a first timing chart in the DC chopper device of the present invention.

FIG. 7 is a second timing chart in the DC chopper device of the present invention.

FIG. 8 is a block diagram of a conventional DC chopper device.

FIG. 9 is a block diagram of a conventional self-excited conversion circuit.

FIG. 10 is a timing chart in a conventional DC chopper circuit.

[Explanation of symbols]

 1: DC chopper device main circuit 11: Self-extinguishing semiconductor switch 12: Reflux diode 13: DC reactor 14: Constant current source 15: DC capacitor 16: Constant voltage source 17: Voltage detecting means 18: Current detecting means 19: Semiconductor Switch drive circuit 2: control circuit 21: voltage setting means 22: adder 23: voltage control means 24: adder 25: current control means 26: carrier wave generation means 27: adder 28: comparator 29: regenerative power compensation means 30 : Load current detecting means 31: operating state compensating means 32: adder 33: conversion circuit switching frequency compensating means 33 a: frequency / voltage converter 33 b: coefficient unit 33 c: contact 34: start-up compensation circuit 34 a: voltage divider 34 b: contact 35 : Adder 5: Self-excited conversion circuit

Claims (3)

(57) [Claims] 1. A main circuit having a semiconductor switch, a reactor, a DC voltage detecting means and a DC current detecting means, and a control circuit having a voltage controlling means for controlling a DC voltage and a current controlling means for controlling a DC current. And a DC chopper device that performs power regeneration by inputting energy absorbed by a snubber circuit connected in parallel to the self-extinguishing device when the self-extinguishing device is commutated in the self-excited conversion circuit. Starting compensation means for outputting a fixed signal for predicting a current flowing into the main circuit of the DC chopper device, switching frequency compensation means for outputting a signal proportional to the switching frequency of the self-extinguishing device, and the DC chopper device. The output of any one of the input current detecting means for detecting the input current of the A DC chopper device characterized in that it is added to an input of a control means. 2. A main circuit having a semiconductor switch, a reactor, a DC voltage detecting means and a DC current detecting means, and a control circuit having a voltage controlling means for controlling a DC voltage and a current controlling means for controlling a DC current. And a DC chopper device that performs power regeneration by inputting energy absorbed by a snubber circuit connected in parallel to the self-extinguishing device when the self-extinguishing device is commutated in the self-excited conversion circuit. Starting compensation means for outputting a fixed signal for predicting a current flowing into the main circuit of the DC chopper device, switching frequency compensation means for outputting a signal proportional to the switching frequency of the self-extinguishing device, and the DC chopper device. A regenerative input that adds and outputs signals from any combination of input current detection means that detects the input current of A DC chopper device comprising compensation means, wherein an output of said regenerative input compensation means is added to an input of said voltage control means or said current control means. 3. A main circuit having a semiconductor switch, a reactor, a DC voltage detecting means and a DC current detecting means, and a control circuit having a voltage controlling means for controlling a DC voltage and a current controlling means for controlling a DC current. And a DC chopper device that performs power regeneration by inputting energy absorbed by a snubber circuit connected in parallel to the self-extinguishing device when the self-extinguishing device is commutated in the self-excited conversion circuit. The snubber circuits connected to the plurality of self-excited conversion circuits are connected in parallel and are provided for each of the snubber circuits, and output a fixed signal for predicting an input current to a main circuit of the DC chopper device. Starting compensation means, switching frequency compensation means for outputting a signal proportional to the switching frequency of the self-extinguishing device, A regenerative input compensating means comprising any combination of input current detecting means for detecting an input current to the DC chopper device, or the starting compensating means, switching frequency compensating means, and input current detecting means;
The output of the regenerative input compensating means is added to the input of the voltage control means or the current control means, and the energy from the plurality of self-excited conversion circuits is regenerated by one DC chopper device. Characteristic DC chopper device.