JPH08308233A - Controller for ac-dc converter - Google Patents

Abstract

PURPOSE: To provide a controller for an AC-DC converter which can continue the rapid and stable operation of an AC-DC converting system. CONSTITUTION: The constant allowance angle regulator circuit 100 in the controller for an AC-DC converter has a high speed constant allowance angle regulator circuit 83, a low speed constant allowance angle regulator circuit 84 and a minimum value selector 91. The circuit 83 inputs the signal generated when a reverse voltage is applied to a semiconductor element for constituting the converter, and outputs a constant allowance angle regulation signal under the calculation control by a long time constant. The circuit 84 inputs the signal generated when the reverse voltage is applied to the element, and outputs a constant allowance angle regulation signal under the calculation control by a short time constant. The selector 91 selects the minimum value of the control signals of the circuits 83 and 84.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC / DC power transmission device which cooperates with a forward converter and an inverse converter, and a control device for an AC / DC converter used in a frequency converter or the like.

[0002]

2. Description of the Related Art FIG. 8 is a diagram showing an AC / DC converter system such as a DC power transmitter and a frequency converter. Reference numerals 10 and 11 are AC systems, 20 and 21 are transformers, 30 is a forward converter, 31 is an inverse converter, 40 and 41 are DC reactors, 50 and 51 are DC lines, and 60 and 61 are control devices.

In FIG. 8, the forward converter 30 is an AC system 1
The AC power from 0 is converted into DC power, and the inverse converter 31 converts the DC power from the forward converter 30 into AC power. In such an AC / DC conversion system, the forward converter 30 side performs constant current control operation, and the inverse converter 31 side performs constant voltage control operation or constant margin angle control operation to exchange power.

FIG. 9 is a block diagram showing the configuration of the control device 61 shown in FIG. Reference numeral 81 is a constant current control circuit (hereinafter referred to as ACR), to which the deviation between the direct current Id from the comparator 88 and the direct current reference value Idp is input. Reference numeral 82 denotes a constant voltage control circuit (hereinafter referred to as AVR), to which the deviation between the DC voltage Vd from the comparator 89 and the DC voltage reference value Vdp is input. 100A is a constant margin angle control circuit (hereinafter referred to as Aγ
(Referred to as R), which has one arithmetic circuit 85 and inputs the reverse voltage period γ applied to the inverse converter 31. Reference numeral 92 denotes a minimum value selection circuit (hereinafter referred to as MIN), which has an ACR8
1, the output signals of AVR82 and AγR100A are respectively input, and the minimum value of these is output. Reference numeral 93 is a phase control circuit, which inputs the output signal of the minimum value selection circuit 92 and outputs an ignition signal synchronized with the system voltage to the forward converter 30 or the inverse converter 31.

Conventionally, the arithmetic circuit 85 of the AγR100A in FIG. 9 inputs the reverse voltage period γ applied to the inverse converter 31 and performs one first-order delay calculation or integral calculation, and the response speed is fixed. .

[0006]

FIG. 10 is a time chart of control signals of the control device 61 of FIG. 8 when an AC system fault occurs. An accident occurred in the AC system 11 at time t1, and the time t
Consider the case of recovery in 2. When an AC system fault occurs at time t1, the reverse voltage period γ applied to the inverse converter 31 disappears, and the AγR 100A advances the phase control angle to the minimum phase control angle αmin in order to secure the reverse voltage period γ. However, since the phase control angle advances over a certain period of time, the reverse voltage period cannot be secured immediately and commutation failure occurs.

At time t2, when the AC system fault recovers, A
γR100A begins to return the control angle, but this time there is a sufficient reverse voltage period γ, so that AγR100A overshoots, the control angle is returned too much, and commutation failure occurs again.

In this way, the arithmetic circuit 8 of the AγR100A
Since there is only one, if the time constant of the control calculation is shortened according to the response required when an accident occurs in the AC system 11, the control angle may return too much and the commutation failure may occur again when the accident is recovered. Further, if the time constant of the control calculation is slowed according to the response required when recovering from the accident, the control angle does not advance during the accident of the AC system 11 and commutation failure continues.

Further, since the DC voltage also decreases during the accident of the AC system 11, the AVR 82 works in the direction of increasing the DC voltage, the control angle sticks to the maximum limiter, and the control angle of the AVR after the accident recovery slows to return. There was a problem. Therefore, an object of the present invention is to provide a control device for an AC / DC converter that can compensate for the above-mentioned problems and continue high-speed and stable operation of the AC / DC conversion system.

[0010]

In order to achieve the above-mentioned object, the invention according to claim 1 is connected to a common DC circuit, and the AC sides are connected to different AC systems, respectively.
A forward converter for converting AC power into DC power, an AC / DC converter comprising an inverse converter for converting the DC power into AC power, and a DC current flowing in a DC circuit of the AC / DC converter and a deviation between DC current references. A constant current control circuit that outputs a current control signal based on the above, a constant voltage control circuit that outputs a voltage control signal based on a deviation between a DC voltage applied to the DC circuit of the AC / DC converter and a DC voltage reference, and the forward converter And a constant margin angle control circuit for inputting a signal generated when a reverse voltage is applied to a semiconductor element forming at least one of the inverse converter and outputting a constant margin angle control signal, and the constant current control circuit. In the controller of the AC / DC converter, which supplies a control signal to a control terminal of the semiconductor element based on a minimum value of output signals of the constant voltage control circuit and the constant margin angle control circuit, The control circuit includes a high-speed constant margin angle control circuit, a low-speed constant margin angle control circuit, and a minimum value selection circuit. The high-speed constant margin angle control circuit outputs a signal generated when a reverse voltage is applied to the semiconductor element. Is input and outputs a constant margin angle control signal that is arithmetically controlled with a short time constant, the low speed constant margin angle control circuit inputs a signal generated when a reverse voltage is applied to the semiconductor element, and The minimum value selection circuit is operated and controlled by a long time constant to output a constant margin angle control signal, and the minimum value selection circuit outputs the minimum value of the constant margin angle control signals of the high speed constant margin angle control circuit and the low speed constant margin angle control circuit. It is something to choose.

In order to achieve the above-mentioned object, the invention corresponding to claim 2 provides a constant margin angle control circuit according to claim 1,
It consists of a high-speed constant margin angle control circuit, a low-speed constant margin angle control circuit, a control phase advance circuit, and a minimum value selection circuit, and the high-speed constant margin angle control circuit is generated when a reverse voltage is applied to the semiconductor element. A signal is input, and a constant margin angle control signal is output by being arithmetically controlled with a short time constant.The low speed constant margin angle control circuit inputs a signal generated when a reverse voltage is applied to the semiconductor element. In addition, the control phase advance circuit inputs a commutation failure detection signal by being controlled by a long time constant and outputs the constant margin angle control signal. The high speed constant margin angle control circuit and the low speed constant margin angle control circuit. Of the constant margin angle control signal is output, and the minimum value selection circuit sets the minimum value of the constant margin angle control signals of the high speed constant margin angle control circuit and the low speed constant margin angle control circuit. Also choose It is.

In order to achieve the above-mentioned object, the invention corresponding to claim 3 provides a constant margin angle control circuit according to claim 1,
It is composed of a high-speed constant margin angle control circuit and a low-speed constant margin angle control circuit, and the high-speed constant margin angle control circuit inputs a signal generated when a reverse voltage is applied to the semiconductor element and calculates with a short time constant. Is controlled to output a constant margin angle control signal, the low speed constant margin angle control circuit inputs a signal generated when a reverse voltage is applied to the semiconductor element, and is arithmetically controlled with a long time constant. An angle control signal is output, and the output of the constant margin angle control signal of the low speed constant margin angle control circuit is limited by the output of the constant margin angle control signal of the high speed constant margin angle control circuit.

In order to achieve the above-mentioned object, the invention corresponding to claim 4 is the constant margin angle control circuit according to claim 1,
It comprises a high-speed constant margin angle control circuit, a low-speed constant margin angle control circuit, and a minimum value selection circuit, and the high-speed constant margin angle control circuit inputs a signal generated when a reverse voltage is applied to the semiconductor element, and The signal is generated when a reverse margin voltage is applied to the semiconductor element by the arithmetic operation control with a short time constant, outputting a constant margin angle control signal and setting the minimum phase angle to 90 degrees. Is input, and a constant margin angle control signal is output by being controlled by a long time constant and a minimum phase angle is set to 90 degrees. The minimum value selection circuit includes the high speed constant margin angle control circuit and the low speed constant angle control circuit. The minimum value of the constant margin angle control signal of the margin angle control circuit is selected.

In order to achieve the above-mentioned object, the invention corresponding to claim 5 is the constant margin angle control circuit according to claim 1,
It comprises a high-speed constant margin angle control circuit, a low-speed constant margin angle control circuit, and a minimum value selection circuit, and the high-speed constant margin angle control circuit inputs a signal generated when a reverse voltage is applied to the semiconductor element, and The low-speed constant margin angle control circuit is operated and controlled by a short time constant to output a constant margin angle control signal, and the low-speed constant margin angle control circuit inputs a signal generated when a reverse voltage is applied to the semiconductor element and has a long time constant. The constant margin angle control signal is arithmetically controlled and output, and the minimum value selection circuit selects the minimum value of the constant margin angle control signals of the high speed constant margin angle control circuit and the low speed constant margin angle control circuit. The output of the constant voltage control circuit is limited by the selected minimum value.

[0015]

According to the invention corresponding to claim 1, as the constant margin angle control circuit included in the control device for the AC / DC converter, the high-speed constant margin angle control circuit rapidly advances the control angle to prevent commutation failure when an AC system fault occurs. It is possible to prevent the commutation failure from occurring again due to the excessive return of the control angle by preventing the continuation and slowly returning the control angle by the low speed constant margin angle control circuit after the accident recovery.

Further, according to the invention corresponding to claim 2, as the constant margin angle control circuit included in the controller of the AC / DC converter according to claim 1, the output of the high speed constant margin angle control circuit and the low speed constant margin angle control are provided. Since the circuit is limited by the output of the circuit that outputs the predetermined phase control advance signal based on the commutation failure detection signal, the control phase advance circuit advances the control angle faster even when the AC system fault period is short. Therefore, it is possible to prevent the commutation failure from continuing, and to slowly return the control angle from an output that is sufficiently smaller than the low-speed constant margin angle control circuit after the accident recovery, and to prevent the commutation failure from occurring again due to the excessive return of the control angle.

Further, according to the invention corresponding to claim 3, as the constant margin angle control circuit included in the controller of the AC / DC converter according to claim 1, the output of the low speed constant margin angle control circuit is controlled by the high speed constant margin angle control. Since it is limited by the output of the circuit,
Even if there is no minimum value selection circuit, in the event of an AC system failure, the high-speed constant margin angle control circuit advances the control angle quickly to prevent continuation of commutation failure, and after the accident recovery, the low-speed constant margin angle control circuit slowly returns the control angle. It is possible to prevent the commutation failure from occurring again due to the excessive return of the control angle.

Further, according to the invention corresponding to claim 4, a constant margin angle control circuit and a low speed constant margin angle control circuit are provided as the constant margin angle control circuit included in the controller of the AC / DC converter according to claim 1. By setting the minimum phase control angle to 90 °, it is possible to prevent the output of the constant margin angle control circuit from being 90 ° during the accident period and to prevent the power flow from being reversed.

According to the invention corresponding to claim 5, the constant margin angle control circuit included in the controller of the AC / DC converter according to claim 1 is a minimum of a high speed constant margin angle control circuit and a low speed constant margin angle control circuit. By limiting the output of the constant voltage control circuit with the output of the value selection circuit, the control angle of the constant voltage control circuit during an AC system fault can be suppressed below a certain value, and the constant voltage control circuit can be controlled after the AC system fault is recovered. It is possible to prevent the DC voltage from overshooting due to a large angle output.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> (Structure of the first embodiment) The first embodiment corresponding to claim 1 of the present invention.
Although the configuration of the embodiment is shown in FIG. 1, only the configuration of the constant margin angle control circuit 100 differs from that of FIG. 1 is the same as that of FIG. 9 already described in FIG. 1, and the other points are the same as those of FIG. 9, and therefore, the same parts as those of FIG. As shown in FIG. 1, the constant margin angle control circuit 100 includes a high speed constant margin angle control circuit (high speed AγR) 83, a low speed constant margin angle control circuit (low speed AγR) 84, and a minimum value selection circuit (MIN) 91. There is.

These functions are as follows. High speed Aγ
R83 performs a calculation with a short time constant, and a constant margin angle control signal b
Is a constant margin angle control circuit that outputs Low speed AγR84
Is a constant margin angle control circuit that performs a calculation with a long time constant and outputs a constant margin angle control signal c. The minimum value selection circuit 91
This is a circuit that selects the smaller one of the outputs b and c of the two constant margin angle control circuits 83 and 84 and outputs the output signal d.

(Operation of First Embodiment) According to the present embodiment,
The constant margin angle control circuit (AγR) 100 is connected to the high-speed AγR83
And the low speed AγR84 and the minimum value selection circuit 91, the control angle can be advanced rapidly by the high speed AγR83 in the case of an AC system accident, and the low speed AγR can be recovered after the accident recovery.
The control angle can be slowly returned with R84.

FIG. 2 is a time chart of a control signal at the time of an AC system fault of the control device using the present invention. Consider a case where an accident occurs in the AC system at time t1 and the system recovers at time t2. When an AC system fault occurs at time t1 and commutation failure occurs, the reverse voltage period γ applied to the converter decreases, and the output of the high-speed AγR83 advances the phase to the minimum phase control angle αmin in a short time. It is controlled by the output of the high speed AγR 83 selected by the minimum value selection circuit 91.

At time t2, when the accident is recovered and the AC system voltage returns, the reverse voltage period γ increases, so that the high speed AγR83
Output returns to the maximum phase control angle direction. The low-speed AγR84 also returns in the maximum phase control angle direction, but returns relatively slowly due to the long time constant.

(Effect of First Embodiment) When an AC system accident occurs at time t1, the control angle can be advanced to the minimum phase control angle in a short time by the high speed AγR83, and commutation failure continues during the AC system accident. Can be prevented.

Further, even if the accident is recovered at time t2, the AC system voltage returns and the reverse voltage period γ increases rapidly, the output of the low speed AγR84 having a long time constant returns slowly, so that the waveform after the accident recovery Recurrence of commutation failure due to strain can be prevented.

As the arithmetic circuit for the high speed AγR83 and the low speed AγR84, a proportional calculation, a first-order lag calculation, a first-order lead-lag calculation, an integral calculation, etc. can be considered. Which one is selected depends on the system condition and the accident condition. High speed AγR
If 83 is calculated by a proportional calculation, the control angle can be minimized without delay as the reverse voltage period γ decreases. Low speed AγR84
Since it is desirable to gradually return the control angle to the larger direction, it is preferable to perform the first-order delay calculation with a long time constant or the integral calculation.

<Second Embodiment> (Configuration of Second Embodiment) Second embodiment corresponding to claim 2 of the present invention
The configuration of the embodiment is shown in FIG. FIG. 1 already described in FIG.
The same components as in FIG.
The difference from FIG. 1 is that a β advance control circuit 86 is newly added. This is because when a AC system accident occurs, a commutation failure detection signal is input from a protection device not shown in the figure, and high speed A
The outputs of γR83 and low-speed AγR84 are temporarily limited.

(Operation of Second Embodiment) According to this embodiment,
By limiting the output of the high-speed AγR83 and the output of the low-speed AγR84 with the output of the β advance control circuit 86, the high-speed AγR83 and the low-speed AγR83 and the low-speed A
The control angle of γR84 can be advanced faster, and after recovery from the accident, the control angle can be slowly returned by low-speed AγR84.

FIG. 4 is a time chart of a control signal when an AC system fault occurs in the control device when the present invention is used. Consider a case where an accident occurs in the AC system at time t1 and the system recovers at time t2. When an AC system accident occurs at time t1 and a commutation failure occurs, the β advance control circuit operates first, and the high speed AγR
The control angle of 83 and the low speed AγR84 is instantly advanced to 120 °. After that, due to the decrease of the reverse voltage period γ applied to the converter, the high speed AγR83 and the low speed AγR84 advance toward the minimum phase control angle αmin.

At time t2, when the accident is recovered and the AC system voltage returns, the reverse voltage period γ increases, so the high speed AγR83
Output returns to the maximum phase control angle direction. The low-speed AγR84 also returns in the maximum phase control angle direction, but returns relatively slowly due to the long time constant.

(Effects of Second Embodiment) In the second embodiment, as shown in the time chart of FIG. 4, the outputs of the high speed AγR83 and the low speed AγR84 are changed to αmi faster than in the first embodiment.
Since it can proceed in the n direction, the reverse voltage period of the converter can be secured quickly, recovery from commutation failure is stopped,
It is possible to send a certain amount of power even during an AC system accident. Further, even if the AC system accident is recovered in a short time, the output of the low speed AγR84 gradually returns from 120 °, so that the commutation failure due to the waveform distortion after the recovery can be prevented from recurring.

<Third Embodiment> (Structure of Third Embodiment) Third embodiment corresponding to claim 3 of the present invention.
The configuration of the embodiment is shown in FIG. FIG. 1 already described in FIG.
1 are denoted by the same reference numerals and the description thereof will be omitted. However, the difference from FIG. 1 is that the output of the low speed AγR 84 is the same as the high speed Aγ.
The point is that the output is limited by R83.

(Operation of Third Embodiment) According to the third embodiment, even if the minimum value selection circuit 91 of the first embodiment is not provided, the control angle can be advanced rapidly by the high speed AγR83 in the event of an AC system fault, After the accident recovery, the control angle can be slowly returned by the low speed AγR84.

(Effect of the third embodiment) When an AC system accident occurs, the control angle can be advanced to the minimum phase control angle in a short time by the high speed AγR83, and continuous commutation failure during the AC system accident can be prevented. Further, even if the accident is recovered, the AC system voltage is returned, and the reverse voltage period γ is rapidly increased, the output of the low speed AγR84 having a long time constant slowly returns from a value smaller than that in the first embodiment. The effect of preventing recurrence of commutation failure due to waveform distortion is large.

<Fourth Embodiment> (Structure of Fourth Embodiment) A fourth embodiment corresponding to claim 4 of the present invention.
The configuration of the embodiment is shown in FIG. FIG. 1 already described in FIG.
Although the same components as in FIG. 1 are assigned the same reference numerals and explanations thereof are omitted, the difference from FIG. 1 is that the minimum phase control angles of the high speed AγR83 and the low speed AγR84 are set to 90 °.

(Operation of Fourth Embodiment) According to the fourth embodiment, the control angle advances only to 90 ° even if the reverse voltage period is reduced due to an AC system fault.

(Effect of the Fourth Embodiment) By setting the minimum phase control angle of the outputs of the low speed AγR84 and the high speed AγR83 to 90 °, even if the reverse voltage period during the AC system fault decreases, Aγ
Since the R phase control angle advances only up to 90 °, it is possible to prevent the power flow from reversing.

<Fifth Embodiment> (Structure of the fifth embodiment) The fifth embodiment of the invention.
The configuration of the embodiment is shown in FIG. FIG. 1 already described in FIG.
1 are denoted by the same reference numerals and description thereof will be omitted. However, the difference from FIG. 1 is the output of the minimum value selection circuit 91 of the high speed AγR83 and the low speed AγR84, and the output of the AVR82 is limited. It was done.

(Operation of the Fifth Embodiment) According to the fifth embodiment, the output of the AVR 82 is prevented from moving in the maximum phase control angle direction even when the AC system fault occurs and the DC voltage becomes small. There is.

(Effect of Fifth Embodiment) The present invention is directed to the AVR82 when the DC voltage becomes small due to an AC system accident or the like.
Since the output of is prevented from moving in the direction of the maximum control phase angle, control after the AC system accident recovery can be performed by the AVR82,
More stable control can be realized than in the first embodiment of FIG.

[0042]

According to the present invention, it is possible to provide a control device for an AC / DC converter capable of continuing high-speed and stable operation of the AC / DC converter system. Specifically, according to the invention corresponding to claim 1, in the case of an AC system accident, the control angle can be advanced by the high speed constant margin angle control circuit to prevent continuation of commutation failure, and after the accident recovery, the low speed constant margin angle control is performed. The circuit can slowly return the control angle to prevent commutation failure again.

According to the invention corresponding to claim 2, since the outputs of the high-speed constant margin angle control circuit and the low-speed constant margin angle control circuit are instantaneously advanced to 120 ° by the output of the control phase advance control circuit, the converter The reverse voltage period of can be secured faster, and a certain amount of power can be sent even during an AC system accident.

According to the invention corresponding to claim 3, since the output of the low speed constant margin angle control circuit is limited by the output of the high speed constant margin angle control circuit, the minimum value selection circuit is not required. The effect of can be expected.

According to the invention according to claim 4, since the output of the constant margin angle control circuit advances only to 90 °, unnecessary power flow reversal at the time of an AC system fault can be prevented. According to the invention corresponding to claim 5, since the outputs of the two constant margin angle control circuits are limited by the output of the minimum value selection circuit, the output after the AC system fault recovery is controlled by the constant voltage control circuit. Can be more stable with.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of a control device for an AC / DC converter according to the present invention.

FIG. 2 is a time chart of control signals for explaining the operation of FIG.

FIG. 3 is a block diagram showing a second embodiment of a control device for an AC / DC converter according to the present invention.

FIG. 4 is a time chart of control signals for explaining the operation of FIG.

FIG. 5 is a block diagram showing a third embodiment of a control device for an AC / DC converter according to the present invention.

FIG. 6 is a block diagram showing a fourth embodiment of a control device for an AC / DC converter according to the present invention.

FIG. 7 is a block diagram showing a fifth embodiment of a control device for an AC / DC converter according to the present invention.

FIG. 8 is a system diagram of a conventional AC / DC conversion system.

FIG. 9 is a block diagram showing an example of a conventional control device for an AC / DC converter.

FIG. 10 is a time chart of a conventional control signal.

[Explanation of symbols]

10, 11 ... AC system, 20, 21 ... Transformer, 30, 3
1 ... Converter, 40, 41 ... DC reactor, 50, 51
... DC line, 81 ... Constant current control circuit (ACR), 82 ...
Constant voltage control circuit (AVR), 83 ... High speed constant margin angle control circuit (high speed AγR), 84 ... Low speed constant margin angle control circuit (low speed AγR), 85 ... Constant margin angle control circuit (conventional AγR),
86 ... β advance control circuit, 88, 89 ... Comparator, 91, 9
2 ... Minimum value selection circuit, 93 ... Phase control circuit, 100 ... Constant margin angle control circuit (AγR).

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Masamori Nobayashi, Masamori Nobayashi, 3-3-22 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture, Kansai Electric Power Co., Inc. (72) Koji Yamaji, 2-5 Marunouchi, Takamatsu City, Kagawa Prefecture Electric power company (72) Inventor Takatsugu Okabe 6-15-1, Ginza, Chuo-ku, Tokyo Power source development Co., Ltd. (72) Inventor Katsumi Egawa No. 1, Toshiba-cho, Fuchu-shi, Tokyo Toshiba Fuchu factory Co., Ltd.

Claims (5)

[Claims] 1. A forward converter that is connected to a common DC circuit and that is connected to different AC systems on different AC sides and that converts AC power into DC power and an inverse converter that converts the DC power into AC power. An AC / DC converter, a constant current control circuit that outputs a current control signal based on the difference between the DC current flowing in the DC circuit of the AC / DC converter and the DC current reference, and a DC voltage applied to the DC circuit of the AC / DC converter. A constant voltage control circuit that outputs a voltage control signal based on a deviation of a DC voltage reference, and a signal that is generated when a reverse voltage is applied to a semiconductor element that constitutes at least one of the forward converter and the reverse converter is input. A constant margin angle control circuit that outputs a constant margin angle control signal, and the semiconductor device based on the minimum value of the output signals of the constant current control circuit, the constant voltage control circuit, and the constant margin angle control circuit. In a controller of an AC / DC converter that supplies a control signal to a control terminal of an element, the constant margin angle control circuit includes a high speed constant margin angle control circuit, a low speed constant margin angle control circuit, and a minimum value selection circuit, The high-speed constant margin angle control circuit inputs a signal generated when a reverse voltage is applied to the semiconductor element, and outputs a constant margin angle control signal which is arithmetically controlled with a short time constant. The angle control circuit inputs a signal generated when a reverse voltage is applied to the semiconductor element and outputs a constant margin angle control signal which is arithmetically controlled with a long time constant, and the minimum value selection circuit is the high speed A controller of an AC / DC converter, which selects a minimum value of a constant margin angle control circuit and a constant margin angle control signal of the low speed constant margin angle control circuit. 2. A forward converter that is connected to a common DC circuit and that is connected to different AC systems on different AC sides, and that includes a forward converter that converts AC power into DC power and an inverse converter that converts the DC power into AC power. An AC / DC converter, a constant current control circuit that outputs a current control signal based on the difference between the DC current flowing in the DC circuit of the AC / DC converter and the DC current reference, and a DC voltage applied to the DC circuit of the AC / DC converter. A constant voltage control circuit that outputs a voltage control signal based on a deviation of a DC voltage reference, and a signal that is generated when a reverse voltage is applied to a semiconductor element that constitutes at least one of the forward converter and the reverse converter is input. A constant margin angle control circuit that outputs a constant margin angle control signal, and the semiconductor device based on the minimum value of the output signals of the constant current control circuit, the constant voltage control circuit, and the constant margin angle control circuit. In a controller of an AC / DC converter that supplies a control signal to a control terminal of an element, the constant margin angle control circuit includes a high speed constant margin angle control circuit, a low speed constant margin angle control circuit, a control phase advance circuit, and a minimum. The high-speed constant margin angle control circuit inputs a signal generated when a reverse voltage is applied to the semiconductor element, and outputs a constant margin angle control signal which is arithmetically controlled with a short time constant. The low-speed constant margin angle control circuit inputs a signal generated when a reverse voltage is applied to the semiconductor element, and outputs a constant margin angle control signal that is arithmetically controlled with a long time constant. The phase advance circuit inputs the commutation failure detection signal and outputs a signal for limiting the output of the constant margin angle control signal of the high speed constant margin angle control circuit and the low speed constant margin angle control circuit. Road control apparatus AC-DC converter and selects the minimum value of the high-speed constant margin angle control circuit and the constant margin angle control signal of the low-speed constant margin angle control circuit. 3. A forward converter that is connected to a common DC circuit and that is connected to different AC systems on different AC sides and that converts AC power into DC power and an inverse converter that converts the DC power into AC power. In the AC / DC converter, a constant current control circuit that outputs a current control signal based on a deviation between a DC current flowing in the DC circuit of the AC / DC converter and a DC current reference, and a DC voltage applied to the DC circuit of the AC / DC converter. A constant voltage control circuit that outputs a voltage control signal based on a deviation of a DC voltage reference, and a signal that is generated when a reverse voltage is applied to a semiconductor element that constitutes at least one of the forward converter and the reverse converter is input. A constant margin angle control circuit that outputs a constant margin angle control signal, based on the minimum value of the output signals of the constant current control circuit, the constant voltage control circuit, and the constant margin angle control circuit, In a controller of an AC / DC converter that supplies a control signal to a control terminal of a semiconductor element, the constant margin angle control circuit includes a high speed constant margin angle control circuit and a low speed constant margin angle control circuit. The angle control circuit inputs a signal generated when a reverse voltage is applied to the semiconductor element, and outputs a constant margin angle control signal which is arithmetically controlled with a short time constant, and the low speed constant margin angle control circuit is A signal generated when a reverse voltage is applied to the semiconductor element is input, and a constant margin angle control signal is output by being arithmetically controlled with a long time constant. The constant margin angle control of the low speed constant margin angle control circuit is performed. A controller for an AC / DC converter, which limits the output of a signal by the output of a constant margin angle control signal of the high-speed constant margin angle control circuit. 4. A forward converter that is connected to a common DC circuit and that is connected to different AC systems on different AC sides and that converts AC power into DC power and an inverse converter that converts the DC power into AC power. In the AC / DC converter, a forward / conversion converter that converts AC power into DC power and an inverse converter that converts the DC power into AC power, wherein a DC current and a DC current flowing in the DC circuit of the AC / DC converter are used. A constant current control circuit that outputs a current control signal based on the deviation of the current reference; and a constant voltage control circuit that outputs a voltage control signal based on the deviation of the DC voltage applied to the DC circuit of the AC / DC converter and the DC voltage reference. A constant margin angle control for inputting a signal generated when a reverse voltage is applied to a semiconductor element forming at least one of the forward converter and the inverse converter and outputting a constant margin angle control signal. Control circuit, based on the minimum value of the output signal of the constant current control circuit, the constant voltage control circuit and the constant margin angle control circuit of the AC-DC converter for supplying a control signal to the control terminal of the semiconductor element. In the control device, the constant margin angle control circuit includes a high-speed constant margin angle control circuit, a low-speed constant margin angle control circuit, and a minimum value selection circuit, and the high-speed constant margin angle control circuit applies a reverse voltage to the semiconductor element. A signal generated when being applied is input, a constant margin angle control signal is output by being arithmetically controlled with a short time constant, and a minimum phase angle is set to 90 degrees. A signal generated when a reverse voltage is applied to the element is input, and a constant margin angle control signal is output by being arithmetically controlled with a long time constant and a minimum phase angle is set to 90 degrees. Road control apparatus AC-DC converter and selects the minimum value of the high-speed constant margin angle control circuit and the constant margin angle control signal of the low-speed constant margin angle control circuit. 5. A forward converter that is connected to a common DC circuit and that is connected to different AC systems on different AC sides and that converts AC power into DC power and an inverse converter that converts the DC power into AC power. An AC / DC converter, a constant current control circuit that outputs a current control signal based on the difference between the DC current flowing in the DC circuit of the AC / DC converter and the DC current reference, and a DC voltage applied to the DC circuit of the AC / DC converter. A constant voltage control circuit that outputs a voltage control signal based on a deviation of a DC voltage reference, and a signal that is generated when a reverse voltage is applied to a semiconductor element that constitutes at least one of the forward converter and the reverse converter is input. A constant margin angle control circuit that outputs a constant margin angle control signal, and the semiconductor device based on the minimum value of the output signals of the constant current control circuit, the constant voltage control circuit, and the constant margin angle control circuit. In a controller of an AC / DC converter that supplies a control signal to a control terminal of an element, the constant margin angle control circuit includes a high speed constant margin angle control circuit, a low speed constant margin angle control circuit, and a minimum value selection circuit, The high-speed constant margin angle control circuit inputs a signal generated when a reverse voltage is applied to the semiconductor element, and outputs a constant margin angle control signal which is arithmetically controlled with a short time constant. The angle control circuit inputs a signal generated when a reverse voltage is applied to the semiconductor element and outputs a constant margin angle control signal which is arithmetically controlled with a long time constant, and the minimum value selection circuit is the high speed In the AC / DC converter, the minimum value of the constant margin angle control signal of the constant margin angle control circuit and the low speed constant margin angle control circuit is selected, and the output of the constant voltage control circuit is limited by the selected minimum value. control Location.