JP4059098B2 - AC-AC power converter backup device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is an AC-AC power converter that directly converts a multi-phase AC voltage to a multi-phase AC voltage using a matrix converter, and can be used even when a power failure occurs or a semiconductor switch that constitutes the matrix converter fails. The present invention relates to a backup device for continuing operation.
[0002]
[Prior art]
FIG. 4 shows a configuration of a conventional AC-AC power converter using a matrix converter. Here, the most common three-phase is illustrated as an example of the polyphase on the input side and output side of the matrix converter, and each phase and AC input terminal on the input side (power supply side) are R, S, T, and output. Each phase and AC output terminal on the side (load side) is U, V, W.
[0003]
In FIG. 4, 10 is a three-phase AC power source, 20 is a three-phase uninterruptible power source connected to the three-phase AC power source 10, and 30 is between AC input terminals R, S, T and AC output terminals U, V, W. This is a matrix converter composed of bidirectional semiconductor switches 31 to 39 connected to each other.
Here, the semiconductor switches 31 to 39 are configured by, for example, connecting two semiconductor switching elements such as IGBTs in series in the reverse direction and connecting a free-wheeling diode to each switching element in antiparallel.
[0004]
In controlling the matrix converter 30, a virtual rectifier 30A and a virtual inverter 30B are assumed in the matrix converter 30 (see FIG. 5), and PWM pulses (switching functions) for these are converted into a rectifier control means 40 and an inverter control means in FIG. 50, and a method of synthesizing both PWM pulses by the PWM pulse synthesizing means 60 and applying them to the matrix converter 30 (for example, “Non-interference control method of input / output reactive power in matrix converter”, Ito (See Rie, Isao Takahashi, SPC-01-121, IEA-01-64, Semiconductor Power Conversion Study Group of the Institute of Electrical Engineers of Japan).
[0005]
On the virtual rectifier 30A side, the rectifier control means 40 compares the input current command with the carrier waveform, generates a PWM pulse on the rectifier 30A side according to the magnitude relationship, and on the virtual inverter 30B side, the inverter control means 50 The output voltage command and the carrier waveform are compared, and the PWM pulse on the inverter 30B side is generated according to the magnitude relationship. By combining these PWM pulses and driving the semiconductor switches 31 to 39 of the matrix converter 30, the input current and the output voltage are controlled according to each command.
Here, the operation of the virtual rectifier 30A is equivalent to the operation of the current-type PWM rectifier because the power supply short circuit is not allowed.
[0006]
Since the matrix converter 30 does not include a large energy buffer composed of a smoothing capacitor and a reactor, the operation must be stopped in the event of a power failure such as a power failure, voltage drop, or significant voltage imbalance. . However, like elevators and industrial plants, there are cases where continuous operation is required even when the power supply is abnormal without stopping the device as much as possible.
Therefore, in order to cope with a power failure, the conventional technique of FIG. 4 includes a three-phase uninterruptible power supply 20 between the three-phase AC power supply 10 and the matrix converter 30. As a result, even when an abnormality occurs in the three-phase AC power source 10, the AC power source is secured by the three-phase uninterruptible power source 20, and the operation of the matrix converter 30 can be continued.
[0007]
Here, the configuration and operation of the matrix converter are described in Non-Patent Document 1 below. Further, the uninterruptible power supply system is described in Non-Patent Document 2.
[0008]
[Non-Patent Document 1]
The Institute of Electrical Engineers of Japan, Semiconductor Power Conversion System Research Committee, “Power Electronics Circuit”, 1st edition, published by Ohm Co., Ltd., November 30, 2000, p. 219-p. 223
[Non-Patent Document 2]
The Institute of Electrical Engineers of Japan, Semiconductor Power Conversion System Research Committee, “Power Electronics Circuit”, 1st edition, published by Ohm Co., Ltd., November 30, 2000, p. 232-p. 235
[0009]
[Problems to be solved by the invention]
As described above, the installation of the three-phase uninterruptible power supply 20 as a countermeasure against power failure not only makes the system expensive, but also enlarges the entire system. In addition, when a factor other than a power supply abnormality, for example, an abnormal situation such as an open failure occurs in the semiconductor switches 31 to 39, the operation must be stopped, and the operation cannot be continued.
[0010]
Accordingly, the present invention is intended to provide an inexpensive and small-sized backup device that can continue operation even when a power failure occurs or a failure occurs in a semiconductor switch of a matrix converter.
[0012]
[Means for Solving the Problems]
To solve the above problems, a first aspect of the present invention, the matrix converter for converting a multi-phase AC voltage to a multi-phase AC voltage,
Fault switch detection means for detecting an input phase to which a faulty semiconductor switch in the matrix converter is connected as a fault phase, and a polyphase supplied to the matrix converter when a fault is detected by the fault switch detection means In place of the AC voltage, means for supplying a DC voltage between lines of the input phase other than the fault phase, and a semiconductor switch connected to the input phase to which the DC voltage is supplied by this means are turned on and off, and the fault phase And a means for turning off all semiconductor switches connected to the.
[0013]
The invention according to claim 2 includes a matrix converter that converts a polyphase AC voltage into a polyphase AC voltage by a virtual rectifier and a virtual inverter, and combines the control pulse of the virtual rectifier and the control pulse of the virtual inverter to combine the control pulse. In the AC-AC power converter given to the matrix converter,
Fault switch detection means for detecting an input phase to which a faulty semiconductor switch in the matrix converter is connected as a fault phase, and a polyphase supplied to the virtual rectifier when a fault is detected by the fault switch detection means In place of the AC voltage, means for supplying a DC voltage between lines of the input phase other than the fault phase, and a semiconductor switch connected to the input phase to which the DC voltage is supplied by this means are turned on and off, and the fault phase And a means for turning off all semiconductor switches connected to the.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a reference embodiment of the present invention. In FIG. 1, the same components as those in FIG. 4 are denoted by the same reference numerals, and the following description will focus on parts different from those in FIG. 4.
[0015]
In FIG. 1, reference numeral 80 denotes a changeover switch connected between the three-phase AC power supply 10 and the matrix converter 30, and includes a switch 81 provided in the R phase and a switch 82 provided in the T phase. .
The switch 81 has a terminal e on the R phase side of the matrix converter 30 and terminals a and b on the R phase and S phase side of the power source 10, and a direct current power source between the terminal b and the S phase of the power source 10. 83 is connected. The switch 82 includes a T-phase side terminal f of the matrix converter 30 and S-phase and T-phase side terminals c and d of the power supply 10. These switches 81 and 82 are switched in conjunction with an abnormality detection signal from a power supply abnormality detection means 70 to be described later. When the three-phase AC power supply 10 is normal, terminals a and e and terminals d and d as shown in the figure. f are connected to each other, and a three-phase AC voltage from the power supply 10 is input to the matrix converter 30.
[0016]
Further, the power supply abnormality detecting means 70 is connected to the three-phase output terminal of the power supply 10, and outputs an abnormality detection signal for switching the changeover switch 80 when the power supply is abnormal, and is specified in the virtual rectifier of the matrix converter 30. In order to turn on the semiconductor switch, a switch-on command is output to the rectifier control means 40.
[0017]
Next, the operation of this reference embodiment will be described.
When a power failure or voltage drop of the three-phase AC power supply 10 or a significant voltage imbalance occurs and an abnormality occurs in the three-phase AC voltage supplied to the matrix converter 30, the power supply abnormality detection means 70 detects these abnormalities. Then, the abnormality detection signal is output to the changeover switch 80. Thereby, the switches 81 and 82 are switched, and the terminals b and e and the terminals c and f are connected to each other.
[0018]
With the above switch operation, the input power source of the matrix converter 30 is switched from the three-phase AC power source 10 to the DC power source 83, and a DC voltage is input to the matrix converter 30. For this reason, the virtual rectifier operation for converting the three-phase alternating current into direct current is unnecessary, and the voltage of the direct current power supply 83 is applied to the virtual direct current link unit by turning on only the semiconductor switch to which the direct current power supply 83 is connected on the virtual rectifier side. Make it appear.
In the example of FIG. 1, the DC power supply 83 when the power failure is connected between the lines of the R phase and the S phase, by turning on the virtual switch S _SN of the virtual switch S _RP and the lower arm of the upper arm in Fig. 5 If the other switches are turned off, the voltage of the virtual DC link unit becomes equal to the voltage of the DC power supply 83. Therefore, the power supply abnormality detecting means 70 in FIG. 1 is a switch for turning on the virtual switches _SRP and _SSN. An ON command is output to the rectifier control means 40.
[0019]
At this time, the virtual inverter in the matrix converter 30 may perform a normal DC-AC conversion operation as in the case where the virtual rectifier is operating.
As a result, even if an abnormality occurs in the three-phase AC power supply 10 (three-phase AC voltage), the operation of the power converter can be continued without changing the magnitude or phase of the output voltage of the matrix converter 30. In particular, in this preferred embodiment, there is no need to use a three-phase uninterruptible power supply 20 as in the prior art of FIG. 4, the power supply abnormality detector 70, the changeover switch 80, since the DC power source 83 such as a relatively inexpensive and compact The cost and size of the device can be reduced.
[0020]
In this reference embodiment, the DC power supply 83 is connected between the R and S phase lines by the changeover switch 80 when a power supply abnormality is detected, but the phase connecting the DC power supply 83 may be between other lines. Further, instead of using one DC power supply, each may be connected between R, S phase and S, T phase lines.
[0021]
Then, the implementation form of the present invention FIG. 2 will be described with reference to FIG. Implementation form of this is equivalent to claim 1, 2 of the invention.
In the present embodiment, as shown in FIG. 2, the failure switch detection means 100 connected to the matrix converter 30 connects the failure detection signal indicating that the semiconductor switch constituting the matrix converter 30 has failed and the failed semiconductor switch. Fault phase information, which is the input phase information, and when the fault is detected, the three-phase AC power supply 10 is disconnected from the input side of the matrix converter 30, and the connection phase switching selection means 94 is connected between the input phase lines other than the fault phase. A DC power supply 95 is connected, and only the semiconductor switches connected to these input phases are controlled to be turned on / off.
[0022]
In FIG. 2, contacts 91, 92, 93 are connected to each phase between the three-phase AC power supply 10 and the matrix converter 30, and these contacts 91, 92, 93 are connected to failure detection signals from the failure switch detection means 100. It is designed to be released in conjunction with. Further, in the changeover switch 90, there is provided connection phase switching selecting means 94 to which a DC power supply 95 is connected, and the DC power supply 95 is connected to each phase on the input side of the matrix converter 30 by the operation inside the selection means 94. Can be selectively connected between two phase wires. Note that the failure detection signal and the failure phase information from the failure switch detection means 100 are input to the connection phase switching selection means 94.
The connection phase switching selection means 94 outputs the input phase (connection phase) to which the DC power supply 95 is connected to the rectifier control means 40 as connection phase information.
[0023]
In this embodiment, an open failure is assumed as the failure of the semiconductor switches 31 to 30. In general, semiconductor switches sometimes have short-circuit faults, but short-circuit faults are often caused by large currents, so open-circuit faults occur as a result of connecting a fast-breaking fuse in series with the switch to prevent short-circuit faults. Can be made. By taking such measures, most faults can be treated as open faults.
The failure detection by the failure switch detection means 100 is, for example, when the switch ON / OFF command and the voltage across the switch are compared, and the voltage across the switch is abnormally high even though the switch ON command is given. This can be realized by determining that the fault is a failure.
[0024]
FIG. 3 shows an operation when a switch failure occurs in the embodiment of FIG.
Since the matrix converter has three input phase semiconductor switches connected to one output phase, even if one of the three input phases fails, chopping can be performed with the other two input phase switches. It is. Therefore, the connection phase switching selection means 94 controls so that the DC power supply 95 is connected between the lines of the two input phases other than the failure phase, and the input phase to which the DC power supply 95 is connected as connection phase information. Is sent to the rectifier control means 40 to turn on / off the switch connected to the.
[0025]
For example, in FIG. 3, when the switch 33 connected to the R phase of the input phase has an open failure, the contacts 91, 92, 93 of FIG. With the phase AC power supply 10 cut off, a DC power supply 95 is connected between the S-phase and T-phase lines of the input phase as shown on the right side of FIG. Further, if the other switches 31 and 32 connected to the R phase are also fixed in the OFF state, the switches 34 to 39 connected to the S phase and the T phase of the input phase are controlled to turn on and off, respectively. An alternating voltage can be output.
That is, all the switches connected to the same input phase (failure phase) as the open failure switch are fixed in the OFF state, and the DC power supply 95 is connected between the lines of the other two input phases (healthy phase). If the switches connected to these two input phases are on / off controlled, the matrix converter 30 can be equivalently operated as an inverter, and an alternating voltage having an arbitrary magnitude and frequency can be generated.
[0026]
The matrix converter can only perform a single-phase AC conversion operation when a phase failure occurs or a switch fails. Since the instantaneous power of single-phase alternating current has a pulsation twice the power supply frequency, a matrix converter that does not have a large energy buffer cannot output constant instantaneous power. However, by connecting a DC power supply 95 to the input side and turning on and off a predetermined switch as in this embodiment, a constant instantaneous power on the input side can be taken out and a constant instantaneous power can be output. Can do. As a result, even when a switch of a certain phase breaks down, it becomes possible to continue the operation without deteriorating the control performance.
[0027]
The present invention is also applicable to interconversion polyphase AC other than three phases described implementation form.
[0028]
【The invention's effect】
As described above, according to the present invention, in an AC-AC power converter that does not have a large-capacity energy buffer such as a matrix converter, a DC voltage is supplied to the input side even when a power supply abnormality occurs or a semiconductor switch fails. Thus, continuous operation is possible by controlling on / off of a predetermined semiconductor switch. In addition, since it can be provided at a low cost with a relatively simple circuit configuration as compared with the prior art equipped with an uninterruptible power supply, improvement in reliability and economy can be expected.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a reference embodiment of the present invention.
2 is a block diagram showing an implementation form of the present invention.
FIG. 3 is an equivalent circuit diagram configured when a certain semiconductor switch fails in FIG. 2;
FIG. 4 is a configuration diagram showing a conventional technique.
FIG. 5 is an equivalent configuration diagram of the main circuit in FIG. 4;
[Explanation of symbols]
10: Three-phase AC power supply 30: Matrix converters 31-39: Semiconductor switch 40: Rectifier control means 50: Inverter control means 60: PWM pulse synthesis means 70: Power supply abnormality detection means 80, 90: Changeover switch 81, 82: Switch 83 , 95: DC power supply 91, 92, 93: Contact 94: Connection phase switching selection means 100: Fault switch detection means af: Terminals R, S, T: AC input terminals U, V, W: AC output terminals

Claims (2)

In the matrix converter for converting a multi-phase AC voltage to a multi-phase AC voltage,
Fault switch detection means for detecting, as a fault phase, an input phase to which a faulty semiconductor switch in the matrix converter is connected;
Means for supplying a DC voltage between the lines of the input phase other than the fault phase instead of the multiphase AC voltage supplied to the matrix converter when a fault is detected by the fault switch detection means;
Means for turning on and off the semiconductor switches connected to the input phase supplied with the DC voltage by this means and turning off all the semiconductor switches connected to the faulty phase ;
A backup device for an AC-AC power converter, comprising: An AC-AC power provided with a matrix converter for converting a polyphase AC voltage into a polyphase AC voltage by a virtual rectifier and a virtual inverter, and combining the control pulse of the virtual rectifier and the control pulse of the virtual inverter to be applied to the matrix converter In the converter ,
Fault switch detection means for detecting, as a fault phase, an input phase to which a faulty semiconductor switch in the matrix converter is connected;
Means for supplying a DC voltage between lines of the input phase other than the fault phase instead of the multi-phase AC voltage supplied to the virtual rectifier when a fault is detected by the fault switch detection means;
Means for turning on and off the semiconductor switches connected to the input phase supplied with the DC voltage by this means and turning off all the semiconductor switches connected to the faulty phase;
A backup device for an AC-AC power converter, comprising:

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