JP4662022B2 - Matrix converter - Google Patents

Description

  The present invention relates to a matrix converter in which each phase of an AC power supply and each phase on the output side are directly connected by a bidirectional switch having a self-extinguishing capability, and in particular, for suppressing a surge voltage and protecting the bidirectional switch. The present invention relates to a matrix converter having a snubber circuit.

  Since the matrix converter directly connects each phase of the AC power supply and each phase on the output side with a bidirectional switch with self-extinguishing capability, the three-phase AC power supply can be directly converted to any voltage / frequency. (For example, refer to Patent Document 1).

  In such a matrix converter, since a power source and a load side are directly connected by a semiconductor element, a snubber circuit is required for protecting the semiconductor element. FIG. 6 illustrates a configuration diagram of such a conventional matrix converter. As shown in FIG. 6, this conventional matrix converter is constituted by a three-phase AC power source 1, an input breaker 2, an input three-phase reactor 3, an input three-phase capacitor 4, and a plurality of bidirectional switches. The matrix converter main circuit 7 and the snubber circuit 14 are configured to control the load motor 8.

  In the conventional matrix converter shown in FIG. 6, the three-phase AC power source 1 and the matrix converter main circuit 7 are connected via a small LC filter including an input three-phase reactor 3 and an input three-phase capacitor 4. It has a configuration.

  The circuit configuration of the snubber circuit 14 will be described with reference to FIG. The snubber circuit 14 is an RCD snubber circuit used in a normal IGBT (Insulated Gate Bipolar Transistor), and diodes 20 and 30, resistors 21 and 31, capacitors 22 and 32 are provided at both ends of the bidirectional switch 23. Is provided.

  In such a conventional matrix converter, as described above, an LC filter is provided for the purpose of removing noise generated when the input side is directly switched by the bidirectional switch of the matrix converter main circuit 7. However, since an AC capacitor is used for the LC filter, a capacitor charging current is generated when the power is turned on. Moreover, since the current passes through the input three-phase reactor 3, voltage resonance is caused as a resonance source of the LC filter. As a result, an excessive voltage surge may occur when the power is turned on. In the circuit configuration shown in FIG. 6, when power is first turned on, the input breaker 2 generally turns on the three phases simultaneously. At this moment, a charge current flows through the input three-phase capacitor 4, but the charge current passes through the input three-phase reactor 3, so that even after the voltage charge is completed, the current continues to flow without interruption. Due to this current increase, the voltage of the input three-phase capacitor 4 jumps to the power supply voltage or more, and in some cases, there is a risk that the breakdown voltage of the bidirectional switch in the matrix converter main circuit 7 is exceeded, leading to destruction.

  The snubber circuit 14 is connected in parallel between both ends of the bidirectional switch, that is, between the input and output of the matrix converter main circuit 7, and has a circuit configuration intended only to suppress the voltage across the bidirectional switch. However, since the surge voltage of the input filter is generated between the input terminals, it is not possible to protect between the terminals by the method of protecting only between the input and output.

  As a protection circuit for the bidirectional switch, a voltage clamp type snubber circuit different from the RCD snubber circuit may be used (see, for example, Patent Documents 2 and 3). A circuit configuration of a matrix converter using such a voltage clamp type snubber circuit is shown in FIG. In FIG. 8, the same components as those in FIG. 6 are denoted by the same reference numerals, and the description thereof is omitted.

  In the matrix converter shown in FIG. 8, the snubber circuit 14 is replaced with a voltage clamp type snubber circuit comprising a snubber diode group 5-1, 5-2 and a snubber capacitor 76 in contrast to the matrix converter shown in FIG. It has a configuration. FIG. 9 shows a specific circuit configuration of the snubber diode groups 5-1 and 5-2 in FIG.

  In this voltage clamp type snubber circuit, a snubber diode group 5-1 is arranged on the input side to protect a bidirectional switch which is a main component of the matrix converter main circuit 7, and a snubber diode group 5- 2 is disposed, and a snubber capacitor 76 is provided in a DC voltage portion rectified by the snubber diode groups 5-1 and 5-2. In this voltage clamp type snubber circuit, the input three-phase power supply is full-wave rectified by the snubber diode group 5-1 and the output three-phase power supply is full-wave rectified by the snubber diode group 5-2.

If using the snubber circuit of the voltage-clamped, since the snubber capacitor 7 6 for voltage clamp is provided, so that the surge voltage generated at the input Furuta also has the voltage suppressing effect during clamped powered on . However, since this snubber circuit exists for protection of the surge voltage of the bidirectional switch, the snubber capacitor 76 is configured with a very small capacitance such as several μF. However, by selecting a snubber capacitor capacitance that allows the snubber circuit that originally exists for protection of the bidirectional switch to suppress surge voltage due to the ingress of the input filter, it is possible to realize stable operation at power-on. Become.

However, since an inrush current also flows through the snubber capacitor 76 when the power is turned on, if the capacitance of the snubber capacitor 76 is increased, a surge voltage is suppressed, but a spike current flows when the initial power is turned on. The inrush current of the snubber circuit is a short but excessive current, and this current may cause further adverse effects on peripheral devices such as surge voltage and noise. Therefore, the capacitance of the snubber capacitor 76 cannot be set to a very large value, and it is difficult to completely suppress the surge voltage only by increasing the capacitance of the snubber capacitor 76.
Japanese Patent Laid-Open No. 11-341807 JP-A-11-262264 JP 2004-9697 A

  The conventional matrix converter described above has a problem that it is not possible to suppress a surge voltage caused by resonance of the input LC filter that occurs when the power is turned on.

  An object of the present invention is to provide a matrix converter capable of suppressing a surge voltage generated due to resonance of an input LC filter when power is turned on.

In order to achieve the above object, a matrix converter according to the present invention includes an LC filter provided on the input side from a three-phase AC power supply, a first snubber diode group for full-wave rectification of the input three-phase power supply, and an output three-phase A voltage clamp type snubber circuit comprising a second snubber diode group for full-wave rectification of a power source and a snubber capacitor connected to a DC voltage unit rectified by the first and second snubber diode groups; Directly connect each phase of the three-phase AC power supply and each phase on the output side with a bidirectional switch having a self-extinguishing capability, and PWM control of the AC power supply voltage in accordance with the output voltage command allows any AC and DC voltage In the matrix converter that outputs
A current suppressing resistor provided between the first snubber diode group and the snubber capacitor, for suppressing a charging current to the snubber capacitor, and a short-circuit contactor for short-circuiting both ends of the current suppressing resistor; A configured snubber inrush current suppression circuit;
Means is provided for detecting a voltage across the snubber capacitor and short-circuiting the short-circuiting contactor when the detected voltage exceeds a certain level.

  According to the present invention, the charging current to the snubber capacitor is suppressed by the current suppression resistor from the time when the power is turned on until the voltage across the snubber capacitor exceeds a certain voltage level. It becomes possible to make a capacity | capacitance large, and it becomes possible to suppress the surge voltage by the resonance of an input LC filter.

Another matrix converter of the present invention includes an LC filter provided on the input side from a three-phase AC power source, a first snubber diode group for full-wave rectification of the input three-phase power source, and an output three-phase power source for a full wave. A voltage clamp type snubber circuit comprising a second snubber diode group to be rectified and a snubber capacitor connected to a DC voltage unit rectified by the first and second snubber diode groups, and the three-phase AC A matrix that directly connects each phase of the power supply and each phase on the output side with a bidirectional switch with self-extinguishing capability, and outputs arbitrary AC and DC voltages by PWM control of the AC power supply voltage according to the output voltage command In the converter
Input filter inrush current suppression composed of a current suppression resistor group connected in series to each phase filter capacitor constituting the LC filter and a short-circuit contactor group for short-circuiting both ends of the current suppression resistor group, respectively Circuit,
And means for short-circuiting the contactor group for short-circuiting when a predetermined time has elapsed since power-on.

  According to the present invention, the contactor group for short-circuiting is in an open state until a certain time has elapsed since the power was turned on, so that the charge current to the filter capacitor of each phase constituting the input LC filter is suppressed by the current suppression resistor group. Will be. Therefore, the surge voltage of the input filter can be suppressed without increasing the capacitance of the snubber capacitor.

  The short-circuit contactor group and the current suppression resistor group include three current suppression resistors respectively provided in three phases of a three-phase AC power supply, and three short-circuit contactors for short-circuiting the three current suppression resistors. Each of the two current suppression resistors provided in any two phases of the three phases of the three-phase AC power supply and two short-circuits for short-circuiting the two current suppression resistors may be configured. You may make it each comprise from a contactor.

  In another matrix converter of the present invention, an input filter resonance suppression capacitor for suppressing a resonance voltage of the input LC filter in a predetermined voltage range between the first snubber diode group and the current suppression resistor. It is good also as composition provided further.

  According to the present invention, the input filter resonance suppression capacitor having a small capacity is provided in front of the current suppression resistor, and the input filter resonance suppression capacitor and the large capacity snubber capacitor via the current suppression resistor are used in combination. Thus, it is possible to more effectively suppress the surge voltage of the input filter. In addition, since all the places where new circuit parts are inserted are in parallel with the main circuit, the main circuit current does not flow as it is, so there is no need for expensive parts for each part, greatly increasing costs. There is no increase.

  Furthermore, another matrix converter of the present invention may further include an input filter resonance suppression resistor group including resistors provided in parallel to the input three-phase reactors constituting the LC filter. Furthermore, you may make it provide the contactor connected in series with respect to each resistance which comprises the said input filter resonance suppression resistance group.

  According to the present invention, since the resistors are provided in parallel to the input three-phase reactors constituting the LC filter provided on the input side, it is possible to suppress the resonance when the input filter enters.

  As described above, according to the present invention, it is possible to obtain an effect that it is possible to suppress a surge voltage generated due to resonance of the input LC filter when the power is turned on.

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

(First embodiment)
FIG. 1 is a diagram showing a circuit configuration of a snubber circuit in the matrix converter according to the first embodiment of the present invention. In FIG. 1, the same components as those in FIG. 8 are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIG. 1, the snubber circuit in the matrix converter according to the present embodiment includes snubber diode groups 5-1 and 5-2, a snubber capacitor 6, and a snubber inrush current suppression circuit 11. The snubber circuit in this embodiment differs from the snubber circuit in the conventional matrix converter shown in FIG. 8 in that the snubber capacitor 76 is replaced with the snubber capacitor 6 and a snubber inrush current suppression circuit 11 is newly provided. Yes.

  The snubber capacitor 6 in the present embodiment has a large capacity of about several hundred μF so that the surge voltage generated due to the input LC filter can be suppressed.

  Further, as shown in FIG. 1, the snubber inrush current suppression circuit 11 is provided between the snubber diode group 5-1 and the snubber capacitor 6, and includes a short-circuit contactor 9-1 and a power suppression resistor 10-1. It consists of and.

  The current suppression resistor 10-1 is provided to suppress the charging current to the snubber capacitor 6, and the short circuit contactor 9-1 is provided to short circuit the current suppression resistor 10-1.

  Although not shown in the figure, the matrix converter of the present embodiment detects the voltage across the snubber capacitor 6 and when this detected voltage exceeds a certain level, the short-circuit contactor 9-1 is detected. Means for short-circuiting are provided.

  In the matrix converter of the present embodiment, first, before the power is turned on, the short-circuit contactor 9-1 is in an open state, and the snubber capacitor 6 is charged via the current suppression resistor 10-1. When the voltage of the snubber capacitor 6 becomes sufficiently large, the short-circuit contactor 9-1 is short-circuited to operate as a normal snubber circuit.

  In the matrix converter according to the present embodiment, the charging current to the snubber capacitor 6 is suppressed by the current suppression resistor 10-1 from when the power is turned on until the voltage across the snubber capacitor 6 reaches a certain voltage level or higher. Therefore, the capacitance of the snubber capacitor 6 can be increased, and a surge voltage due to resonance of the input LC filter can be suppressed.

  As a result, the initial charge current in the snubber circuit can be suppressed, but the effect of reducing the surge voltage of the input filter described above is reduced by the current suppression resistor 10-1.

(Second Embodiment)
Next, a matrix converter according to a second embodiment of the present invention will be described.

  The configuration of the matrix converter according to the second embodiment of the present invention is shown in FIG. The matrix converter according to the present embodiment has a configuration in which an input filter inrush current suppression circuit 12-1 is provided between the input three-phase capacitor 4 and the three-phase AC with respect to the conventional matrix converter shown in FIG. ing. The input filter inrush current suppression circuit 12-1 includes a short-circuit contactor group 9-2 and a current suppression resistor group 10-2.

  The matrix converter of this embodiment has a circuit configuration for the purpose of preventing only the surge voltage of the input filter. An input filter inrush suppression circuit 12-1 is provided between the input three-phase reactor 3 and the input three-phase capacitor 4.

  The current suppression resistor group 10-2 is connected in series to the input three-phase capacitor 4 which is a filter capacitor of each phase constituting the input LC filter. The short-circuit contactor group 9-2 short-circuits both ends of the current suppression resistor group 10-2.

  Although not shown in the figure, the matrix converter according to the present embodiment is provided with means for short-circuiting the short-circuit contactor group 9-2 when a predetermined time has elapsed since the power was turned on.

  The circuit configuration shown in FIG. 2 shows a method using a current suppression resistor group 10-2 and a short-circuit contactor group 9-2 for each of the three phases. However, as shown in FIG. You may make it use the input filter inrush current suppression circuit 12-2 comprised from the current suppression resistance group 10-3 and the short circuit contactor group 9-3 for a phase.

  The short-circuit contactor group 9-2 and the current suppression resistor group 10-2 shown in FIG. 2 short-circuit the three current suppression resistors respectively provided in the three phases of the three-phase AC power supply 1 and the three current suppression resistors. Each of which is composed of three short-circuit contactors. The short-circuit contactor group 9-3 and the current suppression resistor group 10-3 shown in FIG. 3 include two current suppression resistors respectively provided in any two phases of the three phases of the three-phase AC power source 1. Each of the two current suppressing resistors is composed of two short-circuit contactors for short-circuiting.

  In the present embodiment, a method of short-circuiting the short-circuit contactor groups 9-2 and 9-3 when the both-ends voltage of the input three-phase capacitor 4 and the input voltage of the input three-phase reactor 3 are balanced can be considered. However, since it is difficult to detect two three-phase AC voltages, a certain time is calculated in advance, and the short-circuiting contactor groups 9-2 and 9-3 are short-circuited after a certain time has elapsed since the initial application. You can do it.

  In the matrix converter of the present embodiment, the short-circuit contactor groups 9-2 and 9-3 are in an open (open) state until a predetermined time has elapsed since the power is turned on, so the charge current to the input three-phase capacitor 4 is It will be suppressed by the current suppression resistor groups 10-2 and 10-3. Therefore, the surge voltage of the input filter can be suppressed without increasing the capacitance of the snubber capacitor 76.

(Third embodiment)
Next, a matrix converter according to a third embodiment of the present invention will be described.

  In the first embodiment described above, as shown in FIG. 1, when the surge voltage of the input filter is to be suppressed, the capacitance value of the snubber capacitor 6 of the snubber circuit is set to a value larger than a certain level. The snubber inrush current suppression circuit 11 was provided. However, when the power is turned on, the short-circuit contactor 9-1 is in an open state, and the snubber capacitor 6 is connected to the snubber diode group 5-1 through the current suppressing resistor 10-1. For this reason, even when the capacitance of the snubber capacitor 6 is set to a large value of several hundreds μF, the resonance of the input filter may not be suppressed.

  Further, in the second embodiment described above, as shown in FIGS. 2 and 3, the input filter inrush current suppression circuits 12-1 and 12-2 are provided in the input filter unit to suppress the surge voltage. Therefore, it is necessary to insert a short-circuit contactor into a portion where the main circuit current flows. Since this main circuit current flows about several hundred A, the contactor circuit that can be inserted into such a part is expensive. Therefore, when the configuration of the second embodiment is adopted, an increase in cost becomes a problem.

  FIG. 4 shows the configuration of the matrix converter according to the third embodiment of the present invention that solves such a problem. The matrix converter of this embodiment has a configuration in which an input filter resonance suppression capacitor 13 is provided in the snubber circuit with respect to the matrix converter provided with the snubber circuit shown in FIG.

  The input filter resonance suppression capacitor 13 is a capacitor of about several tens of μF, and is provided between the snubber diode group 5-1 and the current suppression resistor 10-1. The resonance voltage of the input LC filter is set within a predetermined voltage range. Suppress. With such a capacitor of about several tens of μF, inrush current at the time of turning on the power does not cause a problem, so that a resistor or the like for suppressing inrush current is not required before the input filter resonance suppression capacitor 13.

  As in this embodiment, a small-capacity input filter resonance suppression capacitor 13 is provided in front of the current suppression resistor 10-1, and a large capacity is provided via the input filter resonance suppression capacitor 13 and the current suppression resistor 10-1. By using the snubber capacitor 6 together, it is possible to more effectively suppress the surge voltage of the input filter. Moreover, in the matrix converter according to the present embodiment, since all the places where new circuit components are inserted are in parallel with the main circuit, the main circuit current does not flow as it is, and thus each component requires an expensive component. However, this is possible without significant cost increase.

(Fourth embodiment)
Next, a matrix converter according to a fourth embodiment of the present invention will be described.

In 3rd Embodiment demonstrated above, the structure for suppressing the resonance at the time of the rush of the input filter resulting from the current suppression resistor 10-1 provided in order to suppress the rush current which flows into the snubber capacitor 6 is shown. It was. In the present embodiment, another configuration for suppressing resonance at the time of entry of the input filter will be described.

  As shown in FIG. 5, the matrix converter of the present embodiment is provided in parallel with each of the input three-phase reactors 3 constituting the LC filter with respect to the matrix converter having the snubber circuit having the configuration shown in FIG. 1. The configuration further includes an input filter resonance suppression resistor group 15 made of resistors.

  Note that the input filter resonance suppression resistor group 15 provided in the present embodiment is only for suppressing resonance when the power is turned on, so that each resistor constituting the input filter resonance suppression resistor group 15 is provided. On the other hand, contactors may be provided in series, and the contactors may be opened when a rush current stops flowing after a certain time or the like has elapsed after the power is turned on.

  According to the present embodiment, since the resistors are provided in parallel to the input three-phase reactors 3 constituting the LC filter provided on the input side, the same as in the third embodiment of the present invention described above. In addition, the effect of suppressing the resonant voltage of the input LC filter can be obtained.

It is a figure which shows the structure of the snubber circuit in the matrix converter of the 1st Embodiment of this invention. It is a figure which shows the circuit structure of the matrix converter of the 2nd Embodiment of this invention. It is a figure which shows the other circuit structure of the matrix converter of the 2nd Embodiment of this invention. It is a figure which shows the circuit structure of the matrix converter of the 3rd Embodiment of this invention. It is a figure which shows the circuit structure of the matrix converter of the 4th Embodiment of this invention. It is a figure which shows the circuit structure of the matrix converter using the conventional RCD snubber circuit. It is a figure for demonstrating the structure of a RCD snubber circuit. It is a figure which shows the circuit structure of the conventional matrix converter using a voltage clamp type snubber circuit. It is a figure which shows the specific circuit structure of the snubber diode group 5-1, 5-2 in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Three-phase AC power supply 2 Input breaker 3 Input three-phase reactor 4 Input three-phase capacitor 5-1 Snubber diode group 5-2 Snubber diode group 6 Snubber capacitor 7 Matrix converter main circuit 8 Load motor 9-1 Short-circuit contactor 9-2 Contactor group for short circuit 9-3 Contactor group for short circuit 10-1 Current suppression resistor 10-2 Current suppression resistor group 10-3 Current suppression resistor group 11 Snubber inrush current suppression circuit 12-1 Input filter inrush current suppression circuit 12-2 Input Filter inrush current suppression circuit 13 Input filter resonance suppression capacitor 14 Snubber circuit 15 Input filter resonance suppression resistor group 20 Diode 21 Resistance 22 Capacitor 23 Bidirectional switch 30 Diode 31 Resistance 32 Capacitor 76 Snubber capacitor

Claims (3)

The LC filter provided on the input side from the three-phase AC power supply, the first snubber diode group for full-wave rectification of the input three-phase power supply, the second snubber diode group for full-wave rectification of the output three-phase power supply, and the first A snubber circuit having a snubber capacitor connected to a DC voltage unit rectified by the first and second snubber diode groups, and each phase of the three-phase AC power supply and each phase of the output three-phase power supply In a matrix converter that directly connects with a direction switch and outputs an arbitrary AC and DC voltage by PWM control of an AC power supply voltage according to an output voltage command,
A current suppressing resistor provided between the first snubber diode group and the snubber capacitor, for suppressing a charging current to the snubber capacitor, and a shorting contactor for short-circuiting both ends of the current suppressing resistor; A snubber inrush current suppression circuit having;
Means for detecting the voltage across the snubber capacitor, and short-circuiting the short-circuit contactor when the detected voltage exceeds a certain level;
A matrix converter comprising: an input filter resonance suppression capacitor for suppressing a resonance voltage of the LC filter within a predetermined voltage range between the first snubber diode group and the current suppression resistor. . The LC filter provided on the input side from the three-phase AC power supply, the first snubber diode group for full-wave rectification of the input three-phase power supply, the second snubber diode group for full-wave rectification of the output three-phase power supply, and the first A snubber circuit having a snubber capacitor connected to a DC voltage unit rectified by the first and second snubber diode groups, and each phase of the three-phase AC power supply and each phase of the output three-phase power supply In a matrix converter that directly connects with a direction switch and outputs an arbitrary AC and DC voltage by PWM control of an AC power supply voltage according to an output voltage command,
A current suppressing resistor provided between the first snubber diode group and the snubber capacitor, for suppressing a charging current to the snubber capacitor, and a shorting contactor for short-circuiting both ends of the current suppressing resistor; A snubber inrush current suppression circuit having;
Means for detecting the voltage across the snubber capacitor, and short-circuiting the short-circuit contactor when the detected voltage exceeds a certain level;
An input filter resonance suppression resistor group consisting of resistors connected in parallel with each phase of the input three-phase reactor constituting the LC filter;
A matrix converter comprising: a contactor connected in series to each resistor constituting the input filter resonance suppression resistor group . The LC filter provided on the input side from the three-phase AC power supply, the first snubber diode group for full-wave rectification of the input three-phase power supply, the second snubber diode group for full-wave rectification of the output three-phase power supply, and the first A snubber circuit having a snubber capacitor connected to a DC voltage unit rectified by the first and second snubber diode groups, and each phase of the three-phase AC power supply and each phase of the output three-phase power supply In a matrix converter that directly connects with a direction switch and outputs an arbitrary AC and DC voltage by PWM control of an AC power supply voltage according to an output voltage command,
A current suppressing resistor provided between the first snubber diode group and the snubber capacitor, for suppressing a charging current to the snubber capacitor, and a shorting contactor for short-circuiting both ends of the current suppressing resistor; A snubber inrush current suppression circuit having;
An input filter comprising a resistor for suppressing a resonance voltage of the LC filter, wherein a connection point between an input three-phase reactor constituting the LC filter and a filter capacitor of each phase constituting the LC filter is extracted. A connection terminal that can connect the resonance suppression resistor group to the outside;
A contactor connected in series to each resistor constituting the input filter resonance suppression resistor group,
The matrix converter, wherein the input filter resonance suppression resistor group is connected in parallel to each phase of the input three-phase reactor via the connection terminal.

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