JP2001061276A - PWM cycloconverter, and its shutoff circuit and shutoff method - Google Patents

Abstract

(57) [Summary] [Problem] To prevent commutation failure even when the output voltage is small or large. SOLUTION: In the PWM cycloconverter, each phase of the AC power supply 1 and each phase on the output side are directly connected by bidirectional switches 10 to 18 having a self-extinguishing capability, and the AC power supply 1 is switched in accordance with an output voltage command. The voltage is PWM-controlled, and an arbitrary AC or DC voltage is output. Bidirectional switch 10-18
Is composed of two unidirectional semiconductor switches, each of which can be turned on / off independently. The voltage direction detection circuit group 7 includes:
The direction of the voltage applied to the bidirectional switches 10 to 18 is detected. The commutation sequence switching circuit group 5 performs a power supply short circuit and an output open based on the output of the voltage direction detection circuit group 7 and the logic state of another gate signal for driving the forward semiconductor switch in the same output phase as the PWM command. The firing order of the bidirectional switches 10 to 18 is switched so as not to occur.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PWM cycloconverter as a power converter for converting an AC voltage into a DC or an AC having a different frequency and amplitude, and more particularly to a PWM converter.
The present invention relates to a method and a circuit for shutting off an M cycloconverter and a commutation sequence control.

[0002]

2. Description of the Related Art FIG. 7 shows a conventional PWM cycloconverter.
This will be described with reference to FIG. This conventional PWM cycloconverter converts an AC voltage from an AC power supply 1 into a DC or an AC having a different frequency and amplitude and supplies it to an AC motor 8. The AC line filter 2 and a power supply voltage detection circuit group 3 , A gate drive circuit 4, a commutation sequence switching circuit group 75, a controller 6, a bidirectional switch module 9, and a power supply voltage comparison circuit 19. The bidirectional switch module 9 is composed of nine bidirectional switches 10 to 18.

[0003] This conventional PWM cycloconverter is
Each phase of the AC power supply 1 and each phase on the output side are directly connected by the bidirectional switches 10 to 18 having self-extinguishing capability, and PWM control of the AC power supply voltage according to the output voltage command to output arbitrary AC and DC voltages. This is a PWM cycloconverter that outputs. The bidirectional switches 10 to 18 are respectively one-way semiconductor switches Tr1 to Tr9 and one-way semiconductor switch T
a circuit consisting of diodes D1 to D9 reversely connected to r1 to Tr9, and a circuit consisting of diodes D1 'to D9' reversely connected to unidirectional semiconductor switches Tr1 'to Tr9' and unidirectional semiconductor switches Tr1 'to Tr9' Are connected in opposing series.

When receiving the output voltage command, the controller 6 determines which bidirectional switch is to be fired while detecting the power supply voltage, and passes the PWM command to the commutation sequence switching circuit group 75. At this time, ideally the bidirectional switch 10
If the switching of .about.18 is performed at the same time, no current spike or voltage spike will occur, but in practice there will be variations in the bidirectional switches and the switching will not be performed at the same time.

The power supply voltage comparison circuit 19 compares the magnitudes of the respective phase voltages and classifies them into a maximum voltage, an intermediate voltage and a minimum voltage.
The information is transmitted as voltage comparison information. Based on the PWM command and the voltage comparison information, the commutation sequence switching circuit group 75 performs commutation from a phase with a large power supply voltage to a small phase (mode 1) or a commutation from a phase with a small power supply voltage to a large phase. (Mode 2) is determined, and a gate signal is generated in a commutation sequence in each mode. The gate driver 4 receives a gate signal, and receives a bidirectional switch 1
A signal insulated from the gate signal is sent to 0 to 18 to drive the bidirectional switches 10 to 18.

Next, the commutation sequence in each mode is shown in FIG. FIG. 8A is a diagram showing a commutation sequence from a phase with a large power supply voltage to a small phase (mode 1), and FIG. 8B is a diagram showing a commutation from a phase with a small power supply voltage to a large phase. It is a figure which shows a mode 2) sequence.

However, in such a conventional PWM cycloconverter, since the commutation mode is detected based on the power supply voltage detected by the voltage comparison circuit 19, when the output voltage is small or the output voltage is large, that is, the commutation is completed. If the next commutation is not started, the commutation failure is likely to occur. Also, commutation failure has occurred when the power supply voltage has a distorted waveform.

In such a PWM cycloconverter, when an abnormality such as a switching element (power transistor) or the like is broken, it is necessary to shut down the operation.

Here, a PWM inverter having a failure detection and protection function will be exemplified, and the case where the shut-off method in the PWM inverter is applied to a PWM cycloconverter will be discussed.

[0010] As a conventional PWM inverter shutoff method, when a shutoff command is input to the PWM inverter,
Control signals to the switching elements that make up the inverter,
That is, a method of turning off all the gate signals is general.

A conventional shut-off method in a PWM inverter will be described with reference to FIG.

A conventional AC motor drive control device to which a PWM inverter is applied is, as shown in FIG.
AC motor 8 by the electric power supplied from the
A diode bridge 832 forming a converter, a smoothing capacitor 833, a transistor module 834 forming an inverter, a gate driver 836 generating a control signal to a gate electrode of the transistor module 834, A controller 807 for outputting a PWM command corresponding to the output voltage command, and a gate driver 836 for PWM command based on the shutoff command BB
And a gate block circuit 837 for controlling the supply to the gate.

In the conventional PWM inverter having such a configuration, first, when the controller 806 creates a PWM command according to an output voltage command, the PWM command is supplied to the gate driver 836 via the gate block circuit 837. . The gate driver 836 insulates the gate signal based on the PWM command, and
Are driven.

Then, if any abnormality occurs, the cutoff signal B
When B is input to the gate block circuit 837, the gate block circuit 837 turns off the supply of the PWM command to the gate driver in all phases. Therefore, the gate signal to the transistor module 834 is turned off in all phases. At this time, the current flowing in the AC motor 8 flows into the smoothing capacitor 833 via the free-foil diode in the transistor module 834, so that a sharp voltage increase at both ends of each transistor in the transistor module 834 is suppressed. Become.

However, when this shut-off method is applied to a PWM cyclo-converter, the PWM cyclo-converter is not provided with an energy absorbing element such as a smoothing capacitor or a free-foil diode.
There has been a problem that a surge voltage is generated at the output terminal of the PWM cycloconverter and the bidirectional switch is destroyed.

[0016]

SUMMARY OF THE INVENTION The above-mentioned conventional PWM
The cycloconverter has the following problems. (1) In the conventional example, when the output voltage is small or the output voltage is large because the voltage comparison circuit detects based on the power supply voltage, that is, when the next commutation starts when commutation is not completed. It was easy to cause a commutation failure. Also, when the power supply voltage has a distorted waveform, commutation failure is also likely to occur. (2) When the above-mentioned conventional shut-off method of the PWM inverter is applied to a PWM cycloconverter, a surge voltage occurs at the output terminal of the PWM cycloconverter because there is no energy absorbing element such as a smoothing capacitor or a free-foil diode. This destroys the bidirectional switch of the PWM cycloconverter.

An object of the present invention is to provide a stable PWM cycloconverter in which commutation failure does not occur even when the output voltage is small or the output voltage is large.

It is another object of the present invention to provide a shutoff circuit that can shut off a PWM cycloconverter without breaking both switches.

[0019]

In order to achieve the above object, a PWM cycloconverter according to the present invention is arranged such that each phase of an AC power supply and each phase on the output side have a self-extinguishing ability and each of them is independent. Directly connected by a bidirectional switch configured by combining two unidirectional semiconductor switches that can be turned on and off,
In a PWM cycloconverter that performs PWM control on the voltage of the AC power supply according to an output voltage command and outputs an arbitrary AC or DC voltage, a voltage direction for detecting the magnitude of the voltage applied to both ends of each bidirectional switch. A switching circuit for switching the firing order of the bidirectional switch based on a detection circuit, an output of the voltage direction detection circuit, a PWM command, and a state of another gate signal for driving a forward semiconductor switch in the same output phase. And a flow sequence switching circuit.

According to the present invention, the magnitude of the voltage across the bidirectional switch is directly detected by the voltage direction detection circuit, and the commutation sequence switching circuit switches the commutation sequence based on the detection result. A drive system using a cycloconverter can be realized.

In order to solve the above problem, the PW of the present invention is used.
In the shutoff circuit of the M cycloconverter, each phase of the AC power supply and each phase on the output side are directly connected by switching means having a self-extinguishing ability, and the switching means is opened and closed by PWM control according to an output current command. In a PWM cycloconverter shutoff circuit for interrupting a PWM cycloconverter that performs control to output an arbitrary AC or DC voltage, the PWM current is controlled based on the output current command.
When a current control means for controlling the output current of the WM cycloconverter and a shutoff command for instructing shutoff of the PWM cycloconverter are input, the output current command is set to zero, and after the output current of the PWM cycloconverter has become zero, Shut-off sequence generating means for shutting off the PWM cycloconverter.

In the shut-off circuit of the PWM cycloconverter according to the present invention, when the shut-off command is received, first, the output current is controlled to zero, and after the output current becomes zero,
Since the shutoff operation is performed, a surge voltage generated in the bidirectional switch of the PWM cycloconverter can be suppressed, a protection circuit and a snubber circuit provided outside can be reduced, and the shutoff can be safely performed without breaking the bidirectional switch.

Further, in another shutoff circuit of the PWM cycloconverter of the present invention, the switching means is constituted by a plurality of bidirectional switches, and the bidirectional switch is constituted by two pairs of unidirectional semiconductor switches. The sequence generating means turns off all or a part of the one-way semiconductor switches included in the PWM cycloconverter when performing the shutoff operation.

[0024]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

(First Embodiment) FIG. 1 is a block diagram showing a configuration of a PWM cycloconverter according to a first embodiment of the present invention. In FIG. 1, the same components as those in FIG. 7 are denoted by the same reference numerals, and description thereof will be omitted.

The PWM cycloconverter of the present embodiment is different from the conventional PWM cycloconverter shown in FIG. 7 in that the power supply voltage comparison circuit 19 is eliminated, the voltage direction detection circuit group 7 is newly provided, and the commutation sequence switching is performed. Circuit group 7
5 is replaced with a commutation sequence switching circuit group 5.

In this embodiment, the bidirectional switches 10-1
8 will be described with a configuration as shown in FIG.
As shown in FIG. 2 (a), two transistors are simply connected in reverse, a reverse current blocking diode is connected as shown in FIG. 2 (b), or a transistor protection diode is connected to an emitter and a transistor as shown in FIG. 2 (c). The present invention can be similarly applied to a case where a device connected between collectors is used.

The voltage direction detection circuit group 7 is connected to the bidirectional switches 10 to 18, and determines the direction of the voltage applied to the bidirectional switches 10 to 18.

The commutation sequence switching circuit group 5 takes in the output of the voltage direction detection circuit group 7 and another gate signal for driving the forward direction semiconductor switch in the same output phase as the PWM command, and The firing order of the bidirectional switches 10 to 18 is switched based on the output and the state of another gate signal for driving the forward semiconductor switch in the same output phase as the PWM command.

The voltage direction detection circuit group 7, the gate driver 4, and the commutation sequence switching circuit group 5 are actually composed of nine voltage direction detection circuits, gate drive circuits, commutation sequence, the same number as the bidirectional switches 10 to 18, respectively. Although it is composed of a switching circuit, three bidirectional switches 10 to 12 and bidirectional switching 10 to 12 corresponding to a circuit per output phase are described here for simplicity.
Only the circuit for controlling the control will be described.

In the voltage direction detection circuit group 7, voltage direction detection circuits 21a to 21c are provided as shown in FIG. In the commutation sequence switching circuit group 5, commutation sequence switching circuits 20a to 20c are provided, and in the gate driver 4, the gate drive circuit 2 is provided.
2a to 22c are provided.

The voltage direction detecting circuit 21a includes a photocoupler 28 for insulating the control side power supply from the main circuit, and a comparator 2
9, first and second diodes 30 ₁ and 30 _2, and an insulated power supply 31. First, second diode 30 _1, 30 ₂ of the cathode is connected to both ends T1, T1 'of the bidirectional switch 10, respectively. Also,
Resistors R3 and R4 are respectively connected between the cathodes of the first and second diodes 30 ₁ and 30 ₂ and the midpoint of the insulated power supply 31 to detect the direction of the voltage even when the transistors Tr1 and Tr1 'are off. can do. The midpoint of the insulated power supply 31 is connected to a connection point E1 of a transistor in the bidirectional switch 10. First and second diodes 3
0 _1, 30 ₂ on the anode side + side and insulated power supply 31 through a resistor, is connected to the input of the comparator 29. Comparator 29
Is connected to the cathode of the light-emitting diode in the photocoupler 28. When the output of the comparator 29 is at a low level (hereinafter referred to as L), the transistor of the photocoupler 28 is conductive and the output Z1 of the voltage direction detector 21 is L. Become.

The circuit configuration of the voltage direction detection circuits 21b and 21c is the same as that of the voltage direction detection circuit 21a, and the description is omitted.

The voltage direction detecting circuits 21a to 21c have the above-described circuit configuration, so that the diode 3
0 determines the direction of the detected voltage applied to the bidirectional switch 10 to 12 to ₁ of the anode potential of the anode and the diode 30 _2.

Next, the operation of the voltage direction detecting circuit 21a will be described.

The first and second diodes 30 ₁ , 30 ₂
Are fixed to the potentials of the terminals to which the respective cathodes are connected (the potentials V1 and V1 'at both ends T1 and T1' of the bidirectional switch). Since the polarity of the anode potential difference changes in the direction in which the voltage is applied, the voltage direction detection signal Z1 output from the voltage direction detector 21a goes high (hereinafter referred to as H) or L, and detects the voltage direction. The voltage direction detection signal Z1 output from the voltage direction detector 21 is L when the potential difference is V1> V1 ', that is, when the potential of the AC power supply 1 is higher than the potential of the AC motor 8;
When V1 <V1 ′, that is, when the potential on the AC power supply 1 side is lower than the potential on the AC motor 8 side, it becomes H.

The output Z1 of the voltage direction detection circuit 21 is input to a commutation sequence switching circuit 20a. The commutation sequence switching circuit 20a has a PWM command C1 from the controller 6 and a forward transistor T in the same output phase.
Gate signals G1, G2, and G3 of other switches input to r1, Tr2, and Tr3 are also input to switch the commutation sequence. From the commutation sequence switching circuit 20,
Forward and reverse transistors T in the same bidirectional switch
Gate signals G1 and G1 ′ for driving r1 and Tr1 ′ are output to drive the bidirectional switch 10. The other bidirectional switches 11 and 12 in the same output phase have the same circuit configuration.

Next, the commutation sequence switching circuit 20a
Will be described with reference to FIG. The commutation sequence switching circuit 20a includes a gate signal selection circuit 25, a mode switching circuit 26, and a delay signal generation circuit 27.

The mode switching circuit 26 has gate signals G1, G2, G of the forward transistors Tr1, Tr2, Tr3 of the bidirectional switches 10, 11, 12 in the same output phase.
3, a voltage direction detection signal Z1, and a PWM command C1. The mode switching circuit 26 includes the forward transistors T of the bidirectional switches 10, 11, and 12 in the same output phase.
Based on the states of the gate signals G1, G2, G3 of r1, Tr2, Tr3, the bidirectional switches 10, within the same output phase,
The voltage directions of 11 and 12 are determined. When the PWM command C1 is H, the mode switching circuit 26 outputs the gate signals G1, G2, G3 of the forward transistors Tr1, Tr2, Tr3 of the bidirectional switches 10, 11, 12 in the same output phase.
Is output as the mode switching signal OUT3, and when the PWM command C1 is L, the voltage direction detection signal Z
1 is output as a mode switching signal OUT3.

The PWM signal C1 is supplied to the delay signal generation circuit 27.
, And generates first and second gate signals OUT1 and OUT2 as outputs. Delay signal generation circuit 27
Inside, a delay circuit 23 having a delay amount of 2ΔT and a delay amount of Δ
T delay circuit 24 is provided. The first gate signal OUT1 is synchronized with the PWM command C1 at the time of rising, and 3 △ T with respect to the PWM command C1 at the time of falling.
Signal delayed by only Also, the second gate signal OU
T2 is 2 △ T with respect to the PWM command C1 at the time of rising.
The signal is synchronized with the PWM command C1 when falling.

The gate signal selection circuit 25 receives the first and second gate signals OUT1 and OUT2 and the mode switching signal OUT3, and outputs the gate signal G1 of the forward transistor Tr1 and the gate signal of the reverse transistor Tr1 '. G1 'is output. Gate signal selection circuit 25
Is to determine whether the gate signal G1 of the forward transistor Tr1 and the gate signal G1 ′ of the reverse transistor Tr1 ′ are the first gate signal OUT1 or the second gate signal OUT2 according to the mode switching signal OUT3. Select The commutation sequence is determined as described above.

Next, the commutation sequence switching circuit 20a
Will be described with reference to FIG. 5A when the voltage is applied from the power supply voltage 1 to the AC motor 8, and FIG. 5B when the voltage is applied from the AC motor 8 to the power supply voltage 1.
Is selected. At this time, the bidirectional switch 1
When 0 is turned on, information on the voltage direction of the other bidirectional switches 11 and 12 in the same output phase, and when turning off the bidirectional switch 10, information on the voltage direction of the bidirectional switch 10 to be turned off is required. You can see that. By using the above commutation sequence, without interrupting the current,
In addition, commutation can be performed without causing a power supply short circuit.

More specifically, when the potential of the AC power supply 1 is higher than that of the AC motor 8 (FIG. 5A), Tr2 is first turned on. At this time, the diode of Tr2 is reverse-biased and no short circuit occurs. Next, Tr1 is turned off. At this time, if a current flows from the AC power supply 1 to the AC motor 8, the current flows through the Tr2 and commutates. When the current is flowing from the AC motor 8 to the AC power supply 1, the current continues to flow through Tr1 '. Next, Tr2 'is turned on. When the current is flowing from the AC motor 8 to the AC power supply 1, the current is commutated from Tr1 'to Tr2' at this time. Finally, Tr1 'is turned off to complete the commutation.

When the potential of the AC motor 8 is higher than that of the AC power supply 1 (FIG. 5B), Tr2 'is turned on first.
At this time, the diode of Tr2 'is reverse-biased and no power supply short circuit occurs. Next, Tr1 'is turned off. At this time, if a current is flowing from the AC motor 8 to the AC power supply 1, the current flows through Tr2 'and commutates. If the current is flowing from the AC power supply 1 to the AC motor 8, the current continues to flow through Tr1. Next, Tr2 is turned on. When current is flowing from the AC motor 8 to the AC power supply 1, at this time, Tr1 to Tr2
Commuted to Finally, Tr1 is turned off to complete the commutation.

(Second Embodiment) Next, the PWM of the present invention will be described.
One embodiment of a method for shutting off a cycloconverter will be described with reference to the drawings. FIG. 6 is a block diagram showing a simple control block of the present embodiment.

The shutoff device of the PWM cycloconverter according to the present embodiment controls the shutoff operation of the PWM cycloconverter 106, and includes a current controller 101, a current command switch 102, and a shutoff sequence generator 103.
, A PWM amplifier 104, and a current sensor 105.

The PWM cycloconverter 106 has a PWM
Based on the PWM pulse output from the M amplifier 104, the voltage of the AC power supply 1 is converted into a PWM voltage, and power for driving the AC motor 1 is supplied.

The current command switch 102 is provided with a cutoff command B
When B is off, the input current command Iref is output as it is, and when the cutoff command BB is turned on, the output current command Iref is set to zero.

The current controller 101 controls the current value of the PWM cycloconverter 106 so that the difference between the current command Iref from the current command switch 102 and the current detection value Ifb becomes zero.

When the shutoff command BB is off, the shutoff sequence generator 103 outputs the output of the current controller 101 to PWM.
The current is output to the amplifier 104, and when the cutoff command BB is turned on, the current detection value Ifb is monitored. When the current detection value Ifb becomes zero, a cutoff sequence is generated and the PWM cycloconverter 106 is cut off.

The PWM amplifier 104 includes the current controller 101
, And generates a PWM pulse having a duty ratio proportional to the output of the PWM cycloconverter 106.

The current sensor 105 detects the current of the AC motor 8 and outputs the detection result to the current controller 101 and the cutoff sequence generator 103 as a current detection value Ifb.

Next, the operation of the cutoff circuit in this embodiment will be described with reference to FIG.

First, the operation when the cutoff signal BB is off will be described.

When the cutoff signal BB is off, the current command switch 102 outputs the input current command Iref as it is. The current controller 101 outputs an instruction such that the difference between the current detection value Ifb and the current command Iref becomes zero.
When the cutoff signal BB is turned off, the cutoff sequence generator 103 outputs the output from the current controller 101 to the PWM amplifier 104 as it is. This allows
The PWM cycloconverter 106 receives the current command Iref
The operation based on the instruction is performed.

Next, the operation when the cutoff signal BB is turned on will be described.

When the cutoff signal BB is turned on, the output of the current command switch 102 becomes zero and the current controller 101
Controls the current so that the current detection value Ifb becomes zero.
The cutoff sequence generator 103 generates a cutoff sequence when the cutoff signal BB is turned on and the current detection value Ifb becomes zero, and the PWM cycloconverter 10
Block 6

When the shut-down sequence generator 103 shuts off the PWM cycloconverter 106, all the unidirectional semiconductor switches included in the PWM cycloconverter 106 may be turned off, or only some of the unidirectional semiconductor switches may be turned off. May be turned off.

According to the shutoff circuit in the PWM cycloconverter of the present embodiment, a surge voltage is not generated since the shutoff operation is performed after the output current becomes zero.

In the present embodiment, the case where the present invention is applied to an AC motor has been described. However, as a motor to be controlled, a DC motor, an induction motor driven by vector control, or a synchronous motor is used. It is apparent that the present invention can be similarly applied to the case where the current control system is controlled by three-phase AC / 2-phase DC conversion (dq conversion).

[0061]

As described above, the present invention has the following effects. (1) In the PWM cycloconverter of the present invention, since the magnitude of the voltage across the bidirectional switch is directly detected and the commutation sequence is switched, a drive system using a stable PWM cycloconverter without malfunction can be realized. (2) In the shutoff method of the PWM cycloconverter according to the present invention, when the shutoff command is received, first, the output current is controlled to zero, and after the output current becomes zero, the shutoff operation is performed. The surge voltage generated in the bidirectional switch can be suppressed, the protection circuit and snubber circuit provided outside can be reduced, and a safe shutoff operation can be realized without breaking the bidirectional switch.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a PWM cycloconverter according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing another configuration of the bidirectional switches 10 to 18;

FIG. 3 is a circuit diagram showing a configuration of a voltage direction detection circuit group 7 and a peripheral circuit configuration;

FIG. 4 is a circuit diagram showing a configuration of a commutation sequence switching circuit 20a in FIG.

FIG. 5 is a diagram showing a commutation sequence by the PWM cycloconverter of the present embodiment.

FIG. 6 is a block diagram showing a shutoff circuit of a PWM cycloconverter according to a second embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of a conventional PWM cyclo converter.

FIG. 8 is a diagram showing a commutation sequence in a conventional PWM cycloconverter.

FIG. 9 is a block diagram showing a configuration of a conventional AC motor drive control device to which a PWM inverter is applied.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 AC power supply 2 AC line filter 3 Power supply voltage detection circuit 4 Gate driver 5 Commutation sequence switching circuit group 6 Controller 7 Voltage direction detection circuit group 8 AC motor 9 Bidirectional switch module 10-18 Bidirectional switch 19 Power supply voltage comparison circuit 20 Commutation sequence switching circuit 21 Voltage direction detection circuit 22 Gate drive circuit 23 Delay circuit (2ΔT) 24 Delay circuit (ΔT) 25 Gate signal selection circuit 26 Mode switching circuit 27 Delay signal generation circuit 28 Photocoupler 29 Comparator 30 ₁ , 30 ₂ First and second diodes 31 Insulated power supply 75 Commutation sequence switching circuit group 101 Current controller 102 Current command switch 103 Shutdown sequence generator 104 PWM amplifier 105 Current sensor 106 PWM cycloconverter 806 Controller 832 Converter (diode module) 833 Smoothing capacitor 834 Transistor module 836 Gate driver 837 Gate block circuit Tr1 to Tr3 Forward transistor Tr1 'to Tr3' Reverse transistor T1 to T3 Power supply side terminal of bidirectional switch T1 'to T3' Load-side terminal of bidirectional switch E1 to E3 Connection point of forward and reverse transistors Z1 to Z3 Voltage direction detection signal G1 to G3 Gate signal of forward transistor G1 'to G3' Gate signal of reverse transistor C1 to C3 PWM Command G OR of gate signals of forward transistors in the same output phase OUT1 First gate signal OUT2 Second gate signal OUT3 Mode switching signal Iref Current command Ifb Current detection value BB cutoff signal

Continuation of the front page (72) Inventor Hidenori Hara 2-1 Kurosaki Castle Stone, Yawatanishi-ku, Kitakyushu-shi, Fukuoka F-term (reference) 5Y750 AA10 BA01 BA06 CC06 DD01 DD25 FF02 FF05

Claims (7)

[Claims] 1. Each phase of an AC power supply and each phase on an output side are:
Directly connected by a bidirectional switch configured by combining two unidirectional semiconductor switches each having a self-extinguishing ability and capable of being turned on and off independently, and PWM-controls the voltage of the AC power supply according to an output voltage command; In a PWM cycloconverter that outputs an arbitrary AC or DC voltage, a voltage direction detection circuit that detects a magnitude of a voltage applied to both ends of each of the bidirectional switches; an output of the voltage direction detection circuit; And a commutation sequence switching circuit that switches the firing order of the bidirectional switches based on the state of another gate signal that drives a forward semiconductor switch in the same output phase. 2. Each phase of the AC power supply and each phase on the output side are:
For shutting off a PWM cycloconverter that is directly connected by a switching means having a self-extinguishing ability and performs an open / close control of the switching means by a PWM control according to an output current command to output an arbitrary AC or DC voltage; In a shutoff circuit of the PWM cycloconverter, a current control means for controlling an output current of the PWM cycloconverter based on the output current command; and a shutoff command for instructing shutoff of the PWM cycloconverter, the output current command Is zero, and the P
A shutoff sequence generating means for shutting off the PWM cycloconverter after the output current of the WM cycloconverter becomes zero. 3. The switching means is constituted by a plurality of bidirectional switches, the bidirectional switch is constituted by two pairs of one-way semiconductor switches. 3. The PWM according to claim 2, wherein all the unidirectional semiconductor switches included in the PWM cycloconverter are turned off.
Cyclo converter shutoff circuit. 4. The switching means is constituted by a plurality of bidirectional switches, the bidirectional switch is constituted by two pairs of one-way semiconductor switches, and the interruption sequence generating means is configured to execute the interruption operation when performing an interruption operation. 3. The P of claim 2, wherein only a part of the one-way semiconductor switch included in the PWM cycloconverter is turned off.
Shutdown circuit of WM cyclo converter. 5. Each phase of the AC power supply and each phase on the output side are:
For shutting off a PWM cycloconverter that is directly connected by a switching means having a self-extinguishing ability and performs an open / close control of the switching means by a PWM control according to an output current command to output an arbitrary AC or DC voltage; In the shutoff method of the PWM cycloconverter, when a shutoff command for shutting down the PWM cycloconverter is input, the output current command is set to zero, and the shutoff of the PWM cycloconverter is performed after the output current of the PWM cycloconverter becomes zero. A method for shutting off a PWM cycloconverter, characterized by performing an operation. 6. The shut-off method of the PWM cyclo-converter according to claim 5, wherein all the one-way semiconductor switches included in the PWM cyclo-converter are turned off when the shut-off operation of the PWM cyclo-converter is performed. 7. The method according to claim 5, wherein when performing the shut-off operation of the PWM cyclo-converter, only a part of the one-way semiconductor switch included in the PWM cyclo-converter is turned off.