JPH10136656A - Starting method of power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a safe and secure starting method which can protect elements from breakdown, etc., by a method, wherein energy is accumulated in the capacitor of an energy recovery circuit before the normal operation of a power converter is started and the energy is regenerated to a DC power supply unit. SOLUTION: If a GTO (self-extinguishing semiconductor switching device) 1a is turned off, a snubber capacitor 4a is discharged, and energy which has been accumulated in a snubber capacitor 4a is transferred to a recovering reactor 8a and, at the same time, recovered by a recovering capacitor 7a. When the discharge of the snubber capacitor 4a is finished, a snubber diode 5a is turned to be electrically continuous, and the energy transferred to the reactor 8a is recovered by the recovering capacitor 7a. The energy recovered by the recovering capacitor 7a is, partially being supplied as the energy of the power supply of a gate drive circuit 12a, regenerated to a DC power supply side 100 by an energy regenerating circuit 11a, so that the initial charging of the capacitor can be performed before the normal operation is started.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for starting a power converter constituted by a self-extinguishing type semiconductor switching element.

[0002]

2. Description of the Related Art A gate turn-off thyristor (hereinafter referred to as G)
The development of a large-capacity power converter using a self-extinguishing type semiconductor element suitable for high-voltage and large-current applications as represented by TO) has been actively conducted. In a power converter applied to the ultra-high voltage field, an arm is configured by connecting a plurality of GTOs in series.

FIG. 23 is a document S of the Institute of Electrical Engineers of Japan in 1992.
It is a figure which shows the conventional power converter shown in PC-92-63 "investigation of the GTO thyristor model for circuit analysis, and the shared voltage at the time of series connection." In the figure, reference numerals 1a and 1h denote GTO1a and GT which are self-extinguishing type semiconductor switch elements.
O1h, 2a, 2h are freewheel diodes, 3
Reference numerals a and 3h denote snubber circuits composed of snubber capacitors 4a and 4h and snubber diodes 5a and 5h. 14
a and 14b are anode reactors, 50a and 50h are snubber resistors, 51a and 51b are reset resistors, 52a and 5b.
2b is a reset diode.

First, the operation when the GTO 1 is turned on from the off state will be described. When the GTO1 is turned on from the off state, a current flows through the GTO1. At this time, since the current flows through the anode reactor 14, the current increase rate di / dt at the time of turning on the GTO is suppressed. When the GTO 1 is turned off, the energy stored in the snubber capacitor 4 is equal to G
When TO1 is turned on, it is consumed by a closed loop snubber resistor 50 including the snubber capacitor 4, the snubber resistor 50, and the GTO1.

Next, the operation when the GTO 1 is turned off from the on state will be described. When the GTO 1 is turned on, the energy stored in the anode reactor 14 is reduced by turning off the GTO 1, the anode reactor 14, the recovery diode 17, and the reset resistor 51.
Is consumed by a closed-loop reset resistor 51 consisting of When GTO1 is turned off from the on state, GTO1 is turned off.
1 is applied with voltage. At this time, the current interrupted by the GTO1 is bypassed to the path including the snubber diode 5 and the snubber capacitor 4, and the snubber capacitor 4 is charged, so that the voltage rise rate dv / dt when the GTO1 is turned off is suppressed.

[0006] When a GTO is used for the power converter, an anode reactor and a snubber circuit are connected to suppress the duty of the GTO during switching. This anode reactor and snubber circuit are
The GTO suppresses the current rise rate di / dt when the GTO is turned on and the voltage rise rate dv / dt when the GTO is turned off.
Has a role of reducing the switching loss. That is,
When the GTO 1 is turned on, the anode reactor 14
Thus, di / dt applied to GTO1 is suppressed, and at the time of turn-off, dv / dt applied to GTO1 is suppressed by snubber capacitor 4. The energy stored in the anode reactor 14 and the snubber capacitor 4 is consumed by the reset resistor 51 and the snubber resistor 50, respectively, to prepare for the next switching.

[0007]

In the conventional large-capacity power converter as described above, since the energy consumed by the snubber resistor and the reset resistor increases, problems such as a decrease in conversion efficiency occur. In order to solve this problem, it is necessary to increase the efficiency of the power converter by regenerating the energy to the DC power supply side. As one of the energy regeneration systems, there is an energy regeneration system in which energy stored in an anode reactor or a snubber capacitor is once recovered by a recovery capacitor, and the energy recovered by the energy recovery circuit is recovered to a DC power supply. However, in this energy regeneration method, it is necessary to consider the reset time of the anode reactor. Here, the reset time is a time until the current flowing through the anode reactor becomes zero amperes.

When resetting the anode reactor with a resistor as in a conventional large-capacity power converter, the reset time is determined by the inductance value of the anode reactor and the resistance value of the reset resistor. On the other hand,
When recovering the energy stored in the anode reactor to the recovery capacitor, the reset time depends on the voltage of the recovery capacitor. Therefore, when the GTO is turned on in a state where the recovery capacitor voltage that can reset the anode reactor within a predetermined time is not secured, the anode reactor is not reset, and thus di / dt applied to the GTO can be suppressed. However, the GTO may cause element destruction. Therefore, the voltage of the recovery capacitor for recovering the energy stored in the anode reactor needs to be set in consideration of the reset time of the anode reactor.

In addition, the power supply of the gate drive circuit necessary for driving the GTO has conventionally been supplied from the low voltage side via an insulating transformer. However, in the case of a power converter in which a large number of GTOs are connected in series to form an arm, if power is supplied to the gate drive circuit from the low-voltage side via an insulating transformer, a large number of very high withstand voltage insulating transformers are required Therefore, a problem such as an increase in the size of the device or an increase in cost occurs. Therefore, a main circuit power supply system for supplying power to the gate drive circuit from the main circuit side is required.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and regenerates energy stored in an anode reactor or a snubber capacitor to a DC power supply by an energy regenerating circuit, and uses a main circuit power supply system to supply power to a gate drive circuit. The power conversion device that supplies energy to the power supply switches the switching element before the normal operation of the power conversion device, thereby recovering the energy stored in the anode reactor to a recovery capacitor, and changing the voltage of the recovery capacitor to a predetermined voltage. Accordingly, it is an object of the present invention to provide a safe and reliable starting method capable of preventing element destruction or the like beforehand.

[0011]

According to the present invention, there is provided a method for starting a power converter, comprising: a DC power supply; a self-extinguishing type switching element connected in series between both poles of the DC power supply; A diode connected in antiparallel to the switching element, a snubber circuit composed of a series body of a snubber capacitor and a snubber diode connected in parallel to the switching element, and an anode reactor connected in series with the switching element between both poles of the DC power supply unit. An energy recovery circuit composed of a series body of a capacitor and a diode connected between the terminals of the anode reactor, and an energy regeneration circuit connected between the capacitor and the DC power supply for regenerating energy stored in the capacitor to the DC power supply. Of a power converter for starting a power converter having a phase having a circuit In the method, before the normal operation of the power conversion device, an energy storage process of causing a current to flow in a closed loop including an anode reactor and an energy recovery circuit by switching a switching element to store energy in a capacitor of the energy recovery circuit. And an energy regeneration process of regenerating the energy stored in the capacitor to the DC power supply unit by the energy regeneration circuit.

A DC power supply unit, a self-extinguishing type switching element connected in series between both poles of the DC power supply unit, a diode connected in antiparallel to the switching element, and a parallel connection to the switching element. A snubber circuit consisting of a series body of a snubber capacitor and a snubber diode, an anode reactor connected in series with a switching element between both poles of a DC power supply unit, and a series connection of a capacitor and a diode connected between terminals of the anode reactor. An energy recovery circuit consisting of a body, an energy recovery circuit connected between the capacitor and the DC power supply to regenerate energy stored in the capacitor to the DC power supply, and an initial charging resistor and recovery connected in parallel with the switching element Between the series body of capacitors and the recovery capacitor and the DC power supply A recovery energy regeneration circuit for recovering the energy recovered by the recovery capacitor to the DC power supply unit and a gate drive circuit connected between the recovery capacitor and the gate of the switching element and supplying the energy recovered by the recovery capacitor to the gate. In a starting method of a power conversion device for starting a power conversion device having a phase having one or both phases, energy is stored in a recovery capacitor via an initial charging resistor before starting normal operation of the power conversion device. Process and a first recovery energy regeneration process in which energy stored in the recovery capacitor is regenerated to a DC power supply by a recovery energy recovery circuit, and a second recovery in which the energy recovered in the recovery capacitor is supplied to the gate by a gate drive circuit Any one of the energy regeneration processes Or with both recovery energy regeneration process, after recovering energy regeneration process,
An energy storage process in which a current flows through a closed loop composed of an anode reactor and an energy recovery circuit by switching a switching element to store energy in a capacitor of the energy recovery circuit, and the energy stored in the capacitor is converted into a direct current by an energy regeneration circuit. Energy regeneration process for regenerating the power supply unit.

Further, the process of accumulating energy includes:
Before the normal operation of the power converter, energy is stored in the recovery capacitor via the initial charging resistor and energy is stored in the snubber capacitor, and the energy storage process is performed by switching the switching element after the recovered energy regeneration process. This is a process in which a current flows through a closed loop composed of an anode reactor and an energy recovery circuit to store energy in a capacitor of the energy recovery circuit and to store energy stored in a snubber capacitor in a recovery capacitor.

Further, the first recovered energy regenerating process is as follows:
The energy of the recovery capacitor is supplied to the recovery energy recovery circuit to drive the recovery energy recovery circuit, and the drive power of the recovery energy recovery circuit is obtained. Then, the energy of the recovery capacitor is recovered to the DC power supply by the recovery energy recovery circuit. Let it. Further, in the second recovered energy regeneration process, the energy of the recovery capacitor is supplied to the gate drive circuit to drive the gate drive circuit, and after the driving power of the gate drive circuit is obtained,
The energy of the recovery capacitor is supplied to the gate by a gate drive circuit.

Further, the voltage of the recovery capacitor is not less than the drive voltage of the recovered energy regeneration circuit or the drive voltage of the gate drive circuit, and is not more than the regeneration operation start voltage of the recovered energy regeneration circuit. Furthermore, the energy regeneration process
After the energy of the capacitor is supplied to the energy regenerating circuit to drive the energy regenerating circuit, and the driving power of the energy regenerating circuit is obtained, the energy of the capacitor is regenerated to the DC power supply by the energy regenerating circuit.

The voltage of the capacitor is not less than the drive voltage of the energy regenerating circuit and not more than the regenerative operation start voltage of the energy regenerating circuit. Further, the voltage of the capacitor is set to be equal to or higher than the voltage at which the anode reactor is reset within a predetermined time and equal to or lower than the regenerative operation start voltage of the energy regenerating circuit.

In the energy storage process, the application time of the gate signal for driving the switching element is set to be longer than the time until the anode reactor is reset. Further, in the energy storage step, energy is stored in the capacitor when the voltage of the capacitor is equal to or lower than a predetermined voltage.

Further, in the starting method of the power conversion device for starting the power conversion device having a plurality of phases connected in parallel to the DC power supply unit, the energy storage process is performed from the plurality of phases of the power conversion device. Set the output line voltage to zero volts. Further, in the method of activating a power conversion device having a plurality of phases connected in parallel to a DC power supply unit, the energy storage process may include a process between output lines output from the plurality of phases of the power conversion device. The voltage is made equal to the line voltage of the power system load connected to the output terminal of the power converter. Furthermore, the switching element is switched according to the line voltage of the power system load connected to the output terminal of the power converter.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a diagram showing a power converter according to a first embodiment of the present invention, and is a diagram of a power converter that regenerates energy stored in a snubber capacitor and an anode reactor to a DC power supply. In the figure, reference numerals 1a and 1h denote self-extinguishing semiconductor switching elements (GTO1a, GTO1).
h), 2a and 2h are freewheel diodes connected in anti-parallel to GTO1a and GTO1h, and 3a and 3h are GTOs.
A snubber circuit connected in parallel to the TO1a and GTO1h and configured by a series circuit of snubber capacitors 4a and 4h and snubber diodes 5a and 5h, and 6a and 6h are recovery capacitors 7a and 7h, recovery reactors 8a and 8h, and a recovery diode 9a, 9h, energy recovery circuits for recovering energy stored in the snubber capacitors 4a, 4h to recovery capacitors 7a, 7h.
0h is an initial charging resistor for initially charging the recovery capacitors 7a and 7h at the time of startup.

11a, 11h are recovery condensers 7a, 7
h, an energy regenerating circuit for regenerating the energy recovered in the DC power supply side 100, 12a and 12h are GTO1a,
Gate drive circuit for driving GTO1h, 13
Reference numerals a and 13h denote optical fibers for transmitting signals from a gate control circuit (not shown) to the gate drive circuits 12a and 12h. 14a and 14b are anode reactors, 15a and 15b are recovery capacitors 16a,
16b, an energy recovery circuit composed of recovery diodes 17a and 17b and recovering energy of the anode reactors 14a and 14b to recovery capacitors 16a and 16b;
Reference numerals 18a and 18b denote energy regenerating circuits for regenerating energy recovered by the recovery capacitors 16a and 16b to the DC power supply side 100. 19 is an output terminal.

The internal configuration of 30b to 30g is 30
Since they are the same as a and 30h, the description is omitted. Also, 3
1a is an upper arm in which four GTOs are connected in series, 31
b is a lower arm in which four GTOs are connected in series, and 40 is a phase.

In a power converter in which a large number of GTOs are connected in series to form an arm, it is necessary to supply energy from a low-voltage side to a power supply for a gate drive circuit through an insulating transformer or the like. It is very difficult from the problem. For this reason, it is necessary to employ a so-called main circuit power supply system in which the energy of the power supply for the gate drive circuit is supplied from the main circuit side as shown in FIG.

In the example shown in FIG. 1, a part of the energy recovered by the recovery capacitor 7 is supplied to the gate drive circuit 12.

As described above, since 30a to 30h have the same configuration, the circuit operations of 30a to 30d when the upper arm 31a performs operations such as turn-on and turn-off are the same. The circuit operations of the lower arms 31e to 30h of the lower arm 31b are all the same. Therefore, the basic circuit operation will be described here, focusing on the portion 30a.

First, the operation when the GTO 1a is turned on from the off state will be described. When the GTO 1a is turned on, the snubber capacitor 4a is discharged via the path 1 shown in FIG. 2A, and the energy stored in the snubber capacitor 4a when the GTO 1a is turned off is transferred to the recovery reactor 8a and simultaneously recovered by the recovery capacitor 7a. When the discharge of the snubber capacitor 4a is completed, the snubber diode 5a conducts, and the energy transferred to the recovery reactor 8a is as shown in FIG.
It is collected by the collection capacitor 7a through the path 2 shown in FIG. That is, by the turn-on operation of the GTO 1a, all the energy stored in the snubber capacitor 4a can be recovered by the recovery capacitor 7a.

Next, the operation when the GTO 1a is turned off from the on state will be described. When the GTO 1a is turned off, the current flowing through the GTO 1a is bypassed to the path 3 shown in FIG. 3A passing through the snubber capacitor 4a and the snubber diode 5a, and the snubber capacitor 4a is charged. At this time, the snubber capacitor 4a is overcharged to a voltage higher than the shared voltage at the time of steady OFF. The overcharged portion of the snubber capacitor 4a is discharged through the path 4 shown in FIG. 3 (b), and the energy is transferred to the recovery reactor 8a and simultaneously recovered by the recovery capacitor 7a. And snubber capacitor 4
When the voltage of a becomes the steady shared voltage, the snubber diode 5
a is conducted, and the energy transferred to the recovery reactor 8a is recovered by the recovery capacitor 7a through the path 2 shown in FIG. 2B. That is, during the turn-off operation of the GTO 1a,
The overcharged energy of the snubber capacitor 4a can be recovered by the recovery capacitor 7a.

Next, a case where the GTO 1a maintains the off state will be described. When the GTO 1a maintains the OFF state, the recovery capacitor 7a is charged by the anode-cathode voltage of the GTO 1a along the path 5 shown in FIG. Thus, the initial charge resistance 10
By connecting “a” and charging the recovery capacitor 7a, energy can be supplied to the power supply of the gate drive circuit 12a, and the on-gate current given to the GTO 1a in the first switching can be secured. If the initial charge resistor 10a is not connected, GTO1a
Before the switching starts, the voltage of the recovery capacitor 7a becomes zero volts, and energy cannot be supplied to the power supply of the gate drive circuit 12a. That is, the power converter cannot be started.

With the above circuit operation, the recovery capacitor 7
A part of the energy recovered in the DC power supply 10a is supplied by the energy regeneration circuit 11a while supplying a part of the energy recovered in the gate drive circuit 12a.
Regenerate to 0. Although not shown, the energy regenerating circuit 11a also needs a power supply for a control circuit, a switching element, and the like. However, it is difficult to supply this power from the low voltage side for the same reason as the power supply of the gate drive circuit 12a. That is, the energy recovered in the recovery capacitor 7a, that is, the energy stored in the snubber capacitor 4a,
Power supply.

FIG. 6 shows a power converter according to the first embodiment of the present invention, which is a three-phase (U-phase, V-phase, W-phase) inverter in which a plurality of GTOs are connected in series to form an arm. .
In the figure, 40a to 40c are phases connected in parallel to the DC power supply 100, and the phases 40a to 40c have the same circuit configuration as the phase 40 shown in FIG. 19a-19c is phase 40
Output terminals from a to 40c, 41 is a DC capacitor connected in parallel with DC power supply 100, and 42 is a motor directly connected to output terminals 19a to 19c and having no voltage before starting the power converter. And so on.

In the initial state of the power converter according to the present embodiment, the DC capacitor 41, the snubber capacitors 4 of the phases 40a to 40c, the recovery capacitors 7, 16 are not charged, and the voltages are all zero volts. It is assumed that all GTOs are turned off.

FIG. 7 is a diagram showing a time chart of a method of starting the power converter shown in FIG. In the figure, Vt
h1 is a voltage at which the recovery capacitor 7 can supply energy to the power supply of the gate drive circuit 12 and the power supply of the energy recovery circuit 11, Vrg1 is a regenerative operation start voltage of the energy recovery circuit 11, and Vth2 is a recovery capacitor 16 of the energy recovery circuit. Vrg2, a voltage capable of supplying energy to the power supply 18, is a regenerative operation start voltage of the energy regenerating circuit 18.

Next, a method of starting the power converter shown in FIG. 6 will be described. First, the DC capacitor 41 is initially charged from the DC power supply 100 to a predetermined DC voltage (E volt). Before starting normal operation, all G
Since TO1 is in the off state, the DC capacitor 41
When the battery is charged to volts and becomes a steady state, all the snubber capacitors 4 are charged to E / 8 volt through the path 6 shown in FIG. 4B. And the recovery condenser 7 is shown in FIG.
7A, the power is gradually supplied through the path 5 shown in FIG. 7A, and energy is supplied to the power supply of the gate drive circuit 12 and the power supply of the energy regeneration circuit 11 after a certain time has elapsed from the start of the initial charging as shown in FIG. The voltage reaches a possible voltage Vth1. Thereafter, the recovery capacitor 7 is further charged and reaches the regenerative operation start voltage Vrg1. After that, the energy recovered by the recovery capacitor 7 in the energy recovery circuit 11 is regenerated to the DC power supply side 100. Here, the regenerative operation start voltage Vrg1 is set to Vth1 or more. As described above, by setting the regenerative operation start voltage Vrg1 of the energy regenerating circuit 11 to Vth1 or more, energy for supplying power to the power source of the gate drive circuit 12 and the power source of the energy regenerating circuit 11 can be secured, and Energy can be regenerated on the DC power supply side 100.

When the initial charging of the DC capacitor 41 is performed in this manner, a current flows through each phase through the path 6 shown in FIG. 4B, and the snubber capacitor 4 is charged to E / 8 volt. In a normal power converter, this charging is performed with a time constant on the order of several seconds. Fig. 4
5B, the current flowing through the path 6 is small, and after the voltage of the snubber capacitor 4 reaches E / 8 volts, FIG.
The value of the current flowing back to the path 7 shown in FIG.
Therefore, the voltage of the recovery capacitor 16 after energy recovery has a very low value.

When the GTO 1 is in the off state, no voltage is applied to the anode reactor 14, so that the initial charging as performed by the recovery capacitor 7 cannot be performed by the recovery capacitor 16. Energy cannot be supplied to the power supply of the energy regeneration circuit 18. As described above, it is impossible to initially charge the recovery capacitor 16 before switching the GTO 1, so that energy cannot be supplied to the power supply of the energy regeneration circuit 18 of the anode reactor 14.

Therefore, a method of starting the power conversion device that can charge the recovery capacitor 16 at an initial stage before the normal operation and supply energy to the power supply of the energy regeneration circuit 18 will be described below. The normal operation referred to here is an operation for driving the motor 42 as a load, that is, an operation in which a current flows through the motor 42. FIG.
When all the phase voltages of the power converters are equal as shown in (1), all the line voltages become zero volts, so that no current flows through the motor 42 as a load. Therefore, in the power converter as shown in FIG. 6, when the GTO 1 is switched so that all the line voltages become zero volts as shown in FIG. Capacitors 7 and 16 can be charged.

Next, a description will be given of a method of starting the power conversion device capable of performing the initial charging of the recovery capacitor 16. First, an initial state will be described. Before the initial charging of the recovery capacitor 16, the DC capacitor 4
1 has been completed, the voltage is in a steady state at E volts, and the recovery capacitor 7 is also charged through the path 5 shown in FIG. 4A, and is connected to the power supply of the gate drive circuit 12 of the GTO 1. A state where energy can be already supplied to the power supply of the energy regeneration circuit 11, that is, Vth
It is assumed to be one or more. Further, it is assumed that all GTOs are turned off. The above-described state is assumed as an initial state of the circuit operation described below. Also,
Although it has already been described that the voltage of the recovery capacitor 16 is extremely low in such an initial state, it is assumed here that the voltage is zero volt for the sake of simplicity.

First, as shown in FIG.
1 are supplied with the same gate signal, and switching is performed so that all three phases have the same phase voltage. At this time, as shown in FIG. 9, the GTO of the upper arm 31a at time t = t1.
1 is turned on, the snubber capacitors 4 of the upper arm 31a are discharged to zero volts in the path 1 shown in FIG.
Is charged to E / 4 volts via the path 8 shown in FIG. Here, the capacitance of the snubber capacitor 4 is CS (F),
The inductance of the anode reactor 14 is LA (H)
Then, during this period, the route 8 shown in FIG.
Is expressed by equation (1), and the time until each voltage of the snubber capacitor 4 of the lower arm 31b becomes E / 4 volt is expressed by equation (2).

[0038] E / 2 {(CS / 4 ) / (2LA)} 1/2 sinω 1 (t-t 1) ··· (1) _{where, ω 1 = 1 / {(} CS / 4) · 2LA ｝ ^1/2

Π / (2ω ₁ ) (2)

When each voltage of the snubber capacitor 4 of the lower arm 31b becomes E / 4 volt, the anode reactor 14
Flows back to the path 7 shown in FIG. Then, the recovery capacitor 16 is charged by recovering the energy stored in the anode reactor 14. The initial value of the recirculating current at this time is expressed by Expression (3) from Expressions (1) and (2). This period ends when the current of the anode reactor 14 becomes zero amperes.

E / 2 {(CS / 4) / (2LA)} ^1/2 (3)

When the current circulating through the path 7 shown in FIG. 5A becomes zero ampere, the GTO1 of the upper arm 31a
Is completed. If the charged voltage of the recovery capacitor 16 at this time does not reach the voltage Vth2 necessary for supplying energy to the power supply of the energy regenerating circuit 18, the time t = t2 as shown in FIG. Turns off GTO1 of upper arm 31a at time t = t3, and turns off GTO1 of lower arm 31b at time t = t3.
Turn 1 on. In the gate signal shown in FIG. 9, the time (t3-t2) is an upper and lower arm short circuit prevention time Td set in advance to prevent a short circuit between the upper and lower arms. According to FIG. 9, the GTO1 of the upper arm 31a is
Is turned on, the time until the GTO1 of the lower arm 31b turns on is (t3-t1). Here, the time (t3-t1) must always be set to be longer than the time obtained by adding the reset time of the anode reactor 14 (described in detail below) to the time of Expression (2).

Incidentally, the GT of the upper arm 31a described above is used.
A series of operation times associated with the turn-on of O1 is a time obtained by adding the equation (2) and the reset time of the anode reactor 14, and when this is T1, for example, the DC voltage E = 120
Assuming that 00V, CS = 6 μF, LA = 40 μH, and the voltage VCO of the recovery capacitor 16 = 0 V, T1 ≒ 332 μs
Becomes Then, the time (t3-t)
1) must be set long. In the previous example, if (t3−t1) <T1 (= 332 μs)
In this case, the GTO1 of the lower arm 31b is turned on in a state where the anode reactor 14 has not been reset. Therefore, (t3−t1)> T1 must be satisfied.

Also, for the operation after time t = t3 shown in FIG. 9, that is, for a series of operations after the GTO1 of the lower arm 31b is turned on, an equation is derived in the same manner as before, and until the operation is completed. It is possible to calculate the time. Therefore, the time (t5-t) shown in FIG.
For 3), (t7-t5), etc., different times can be set. However, in the above example, (t3-t1) = (t5-t3) = (t7-t5)
If the power converter is operated by pulse width modulation (PWM), a signal as shown in FIG. 8 can be obtained by setting the modulation factor to zero. (T3-t1) = (t5-t3) = (t7-t5) =
, Which simplifies the configuration of the gate control circuit and the like.

Thereafter, the switching as shown in FIG. 9 is repeated until the voltage of the recovery capacitor 16 reaches at least the voltage Vth2 necessary for supplying energy to the power supply of the energy regenerating circuit 18. When the above-described switching is performed, the energy is also recovered in the recovery capacitor 7, and the voltage thereof rises. Therefore, when the voltage of the recovery capacitor 7 becomes equal to or higher than the regeneration operation start voltage Vrg1 of the energy regeneration circuit 11, energy is regenerated to the DC power supply side 100. Then, after the voltage of the recovery capacitor 16 is charged to the predetermined voltage Vth2 or more, the normal operation of the power converter is started.

Next, the reset time of the anode reactor 14 will be described. The reset time is a time required for the current flowing through the anode reactor 14 to flow back through the path 7 shown in FIG. 5A until the current reaches zero amperes. This reset time is, as explained below,
It largely depends on the initial voltage of the recovery capacitor 16 immediately before the current of the anode reactor 14 returns. First, its characteristics will be described.

The initial current of the anode reactor 14 at the time (t = tx) immediately before refluxing at the path 7 shown in FIG. 5A is I1 ampere, the inductance of the anode reactor 14 is LA Henry, the recovery capacitor 16 is Assuming that the initial voltage is V1 volt and the capacitance of the recovery capacitor 16 is CO Farad, the current flowing through the path 7 shown in FIG. 5A is expressed by equation (4), and the current becomes zero amperes from time (t = tx). Time (ty-t) until time (t = ty)
x) is represented by equation (5).

[0048] ^{_{{I 1 2 + (ω 2}} · CO · V 1) 2} 1/2 × sin {tan -1 _{[I 1 / (ω 2 · CO} · V 1) ] - ω ₂ (t-tx) ｝ (4) where ω ₂ = 1 / (LA · CO) ^1/2

(1 / ω ₂ ) tan ^-1 {I ₁ / (ω ₂ · CO · V ₁ )} (5)

With respect to the reset time (ty-tx) of the anode reactor 14 in the equation (5), specific numerical values are given to graph the characteristics. FIG. 10 shows that LA = 40 μ
11 is a graph showing the dependence of the reset time (ty-tx) on the initial voltage V1 of the recovery capacitor 16 when H, CO = 1000 μF, and I1 = 2000A. Reset time (ty-tx) as shown in FIG.
Is shorter as the initial voltage V1 of the recovery capacitor 16 is higher. Also, as is clear from equation (5), when V1 = 0 volt, the reset time does not depend on I1, but is determined only by the values of LA and CO.
It can also be seen that the reset time at that time takes the maximum value.

In the present embodiment, the energy stored in the recovery capacitor is supplied to both the power source of the gate drive circuit and the power source of the energy regenerating circuit and is regenerated to the DC power source. However, the present invention is not limited to this. The energy may be supplied only to the power supply of the power supply. Further, in the present embodiment, the motor is connected to the output terminal. However, the present invention is not limited to the motor, but may be any load that does not have a voltage before the power converter is started.

According to the above procedure, the normal operation can be started after the energy of the power supply of the gate drive circuit 12 and the energy of the power supply of the energy regeneration circuits 11 and 18 are secured.

Embodiment 2 FIG. 11 is a diagram showing a time chart of a method of starting the power converter according to Embodiment 2 of the present invention. In the figure, Vth1 is a voltage at which the recovery capacitor 7 can supply energy to the power supply of the gate drive circuit 12 and the power supply of the energy regeneration circuit 11,
Vrg1 is the regenerative operation start voltage of the energy regenerative circuit 11, Vth2 is the voltage at which the recovery capacitor 16 can supply energy to the power supply of the energy regenerative circuit 18, Vrg2 is the regenerative operation start voltage of the energy regenerative circuit 18, and Vth3 is Vth2 or more. It is an initial charging voltage of Vrg2 or less.

In the first embodiment shown in FIG. 7, the recovery capacitor 16 is initially charged to a voltage Vth2 or more necessary for supplying energy to the power supply of the energy regeneration circuit 18. On the other hand, in the present embodiment, by setting the initial charging voltage Vth3 to a voltage value described below, the anode reactor 14 can be surely reset within a predetermined time.

A method for setting the initial charging voltage Vth3 will be described. The fact that the reset time of the anode reactor 14 depends on the initial voltage of the recovery capacitor 16 has already been described in the first embodiment, but the same applies to the normal operation. Therefore, the voltage of the recovery capacitor 16 during the normal operation needs to be equal to or higher than the minimum voltage Vth3 at which the anode reactor 14 can be reliably reset within a predetermined time in any assumed state.

For example, during normal operation when the power converter is driven by PWM and a motor as a load is driven, a minimum pulse of PWM is output, and when the maximum load current is cut off by GTO1 at that time. In this case, the most severe condition assumed for the restriction of the reset time of the anode reactor 14 is attained. However, even in such a state, it is necessary to surely reset the anode reactor 14 before the coming turn-on of the GTO 1, so that the minimum voltage of the recovery capacitor 16 is initially set so as to satisfy the restriction. It is necessary to always be able to secure the charging voltage Vth3 or more. Therefore, in such a case, the initial charging voltage of the recovery capacitor 16 is set to be equal to or higher than the initial charging voltage Vth3.

In consideration of the normal operation pattern after the power converter is started, if the above-mentioned severe condition is not assumed immediately after the start, the recovery capacitor 16 to be operated before the normal operation is started. A voltage lower than the above-described initial charging voltage Vth3 may be set as the minimum charging voltage.

When the initial charging voltage Vth3 of the recovery capacitor 16 is set to any voltage, the initial charging voltage Vth3 is the minimum voltage Vth required to supply energy to the power supply of the energy regenerating circuit 18.
It is necessary to keep at least two. If the setting is not made in this manner, the power converter is started in a state where energy is not secured in the power supply of the energy regeneration circuit 18.

Next, the time chart shown in FIG. 11 will be described. As shown in FIG. 11, the energy regeneration circuit 1
8 is equal to the aforementioned minimum voltage Vth.
3 or more, and the voltage of the recovery capacitor 16 is Vth
When it becomes 3, the initial charging operation of the recovery capacitor 16 is stopped. Also, the minimum voltage Vth2 required to supply energy to the power supply of the energy regenerative circuit 18
Is set to be equal to or lower than the above-described minimum voltage Vth3, energy for supplying to the power supply of the energy regenerating circuit 18 can be secured, and more energy can be regenerated to the DC power supply side.

Embodiment 3 FIG. 12 is a diagram showing a power conversion device according to Embodiment 3 of the present invention. In the figure, 40a
The phases 40c to 40c are connected in parallel to the DC power supply 100, and the phases 40a to 40c have the same circuit configuration as the phase 40 shown in FIG. 19a to 19c are output terminals from the phases 40a to 40c, 41 is a DC capacitor connected in parallel with the DC power supply 100, and 42 is a motor connected to the output terminals 19a to 19c via a circuit breaker 43. It is.

According to the first embodiment of the present invention, the starting of the power converter when a load having no voltage is directly connected to the output terminal 19 before the power converter such as a motor is started. The method was explained. On the other hand, in the present embodiment, as shown in FIG. 12, the circuit breaker 43 is connected between the output terminal 19 and the load, and the circuit breaker 43 is opened before the normal operation starts. A method of starting the power converter of the first embodiment will be described. In addition,
In the present embodiment, the circuit breaker 43 before the start of the normal operation is open, so that the load is not limited to the motor or the like, and the recovery capacitor is not limited to a power system having a voltage before the power converter is started. The initial charging method for 7 and 16 is the same.

An initial state in the present embodiment will be described. In the initial state of the present embodiment, it is assumed that the initial charging of the DC capacitor 41 has been completed, the voltage thereof is in a steady state at E volts, and the recovery capacitor 7 is also connected via the path 5 shown in FIG. Charged, GTO1 gate drive circuit 1
It is assumed that energy can be already supplied to the power supply 2 and the power supply of the energy regeneration circuit 11. It is assumed that GTO1 is all turned off. Although it has already been described that the voltage of the recovery capacitor 16 is very low in this initial state, it is assumed that this voltage is zero volt for the sake of simplicity.

In this embodiment, since the circuit breaker 43 is open, no voltage is applied to the load and the load current is reduced regardless of the phase voltage output to the output terminal 19 of the power converter. Not flowing. Therefore, regarding the switching for performing the initial charging of the recovery capacitor 16, it is not necessary to particularly set the line voltage to zero volt, and it is only necessary to pay attention to the reset time of the anode reactor 14 described above.

The method of activating the power conversion device of the present embodiment is the same as that of the first embodiment except for the gate signal applied to GTO1, and the other description is omitted. FIG. 13 shows a gate signal according to the third embodiment of the present invention.
(A) is a figure which shows the example of the gate signal with which a line voltage changes. Here, it is assumed that the initial charge of the recovery capacitor 16 is started, for example, using the rising edge of the gate signal pulse in FIG. The timing may be from time t1 to t6, and it is assumed that the initial charging is started at time t3. All GT
Since O1 maintains the off state immediately before the initial charging of the recovery capacitor 16, the gate signal actually given to each GTO1 is the gate signal as shown in FIG. In this case, (t4-t3) in FIG.
If the W-phase anode reactor 14 is reset within the time, it can be understood that there is no problem with the reset time for the anode reactors 14 of the other phases.

Next, assuming that the initial charging is started at time t4 shown in FIG. 13A, the gate signal actually applied to each GTO1 becomes as shown in FIG. It can be seen that the pulse width of the gate signal applied to the GTO1 of the arm becomes particularly short. And (t5-t in the figure)
4) When the anode reactor 14 is not reset within the time, that is, when (t5−t4) <T1 (T1 is defined in the first embodiment), the V-phase lower arm GTO1 May have a high di / dt at turn-on. Therefore, it is necessary not to start the initial charging operation of the recovery capacitor 16 at such a timing.

As the timing for starting the initial charging of the recovery capacitor 16, it is possible not to use the rising edge of the gate signal pulse. However, even in this case, when the GTO 1 is turned on, the anode reactor 14 must be reset. Need to be done.

In the first embodiment, since the recovery capacitor 16 is initially charged using a gate signal such that the line voltage becomes zero volt, the voltages of the recovery capacitors 16 of each phase are all equal at the same time. . However, when the recovery capacitor 16 is initially charged using the gate signal as shown in FIG. 13, it is necessary to pay attention to the fact that the voltages of the recovery capacitors 16 of the respective phases do not become equal at the same time. That is, even if the recovery capacitor 16 of a certain phase reaches a predetermined voltage at a certain time, the recovery capacitor 16 of another phase does not necessarily reach the predetermined voltage at that time. Therefore, when only the voltage of the recovery capacitor 16 of a certain phase is measured and the power converter is started based on the measured voltage, the energy is not supplied to the power supply of the energy recovery circuit 18 of the other phase, or the anode reactor during normal operation is not used. There is a possibility that a problem such as the restriction of the reset time of No. 14 not being satisfied may occur. Therefore, FIG.
3 using the gate signal as shown in FIG.
When the battery 6 is initially charged, the voltages of the recovery capacitors 16 of all the arms are measured, and the normal operation is started when the voltages of all the recovery capacitors 16 become equal to or higher than a predetermined voltage.

Note that, even when the output terminal 19 is opened from the load side by the circuit breaker 43, as shown in the first embodiment, the G signal is applied to the gate signal at which the line voltage becomes zero volt.
The recovery capacitor 16 may be initially charged by switching the TO1. Also in this case, it is needless to say that it is necessary to prepare a gate signal in consideration of the reset time of the anode reactor 14.

In the present embodiment, when the output terminal 19 is opened from the load side by the circuit breaker 43, FIG.
By switching the GTO 1 with a gate signal such that the line voltage does not become zero volt as shown in FIG. 3, the recovery capacitor 16 can be initially charged.
A gate signal as shown in FIG. 13 can be easily obtained from a normal gate control circuit in a power converter operated by PWM, and a special gate control circuit for initial charging of the recovery capacitor 16 is used. Need not be prepared, and the configuration of the power converter can be prevented from becoming complicated.

Embodiment 4 FIG. 14 is a diagram showing a power converter according to a fourth embodiment of the present invention. In the figure, 40a
The phases 40c to 40c are connected in parallel to the DC power supply 100, and the phases 40a to 40c have the same circuit configuration as the phase 40 shown in FIG. 19a to 19c are output terminals from the phases 40a to 40c, 41 is a DC capacitor connected in parallel with the DC power supply 100, and 44 is an output terminal 19a to 19c.
Is a power system which is a load connected to the power supply via a circuit breaker 43.

In the first and second embodiments, the method of starting the power converter in which the load connected to the power converter has no voltage before starting the power converter, such as a motor, has been described. . On the other hand, in the present embodiment, as shown in FIG. 14, when the load connected to the power converter has a voltage before starting the power system, that is, the power converter, the power converter starts up. The method will be described.

In the power converter shown in FIG. 14, after the DC capacitor 41 is initially charged, when the circuit breaker 43 is turned on with the voltage of the recovery capacitor 16 at zero volt, the power system 44 as a load is connected to the power system 44. The recovery capacitor 16 must be initially charged with the power converter connected.

First, an initial state of the power converter shown in FIG. 14 will be described. First, it is assumed that all the GTOs 1 are off and the circuit breakers 43 are open. The DC capacitor 41 is charged from the DC power supply 100 to a predetermined DC voltage E volt and is in a steady state. At this time, since all the GTOs 1 are off, the voltages of all the snubber capacitors 4 become E / 8 volts. Then, the recovery capacitor 7 is charged through the path 5 shown in FIG. 4A and is in a state where it can supply energy to the power supply of the gate drive circuit 12 and the power supply of the energy regeneration circuit 11 of the GTO 1. And The circuit breaker 43 is assumed to be open at least until the initial charging of the DC capacitor 41 is completed. From this state, the circuit breaker 43 is turned on to connect the power converter and the power system 44 as a load.

When the circuit breaker 43 is turned on, the line voltage of the power converter is controlled by the line voltage on the system side, so that the voltage of the snubber capacitor 4 changes in synchronization with the system voltage. When the voltage of the snubber capacitor 4 changes, the recovery capacitor 7 is charged because energy is recovered in the recovery capacitor 7, but the recovery capacitor 16 is hardly charged. The reason will be described below.

As described above, since the line voltage of the power converter is governed by the line voltage on the system side, the voltage of the snubber capacitor 4 fluctuates at the system frequency. Here, the system frequency is 60 Hz, and the inductance of the anode reactor is 4
Assuming 0 μH, the impedance is 2 × π × 60H
z × 40 μH ≒ 0.015Ω. Therefore, even if a current of 100 A flows when the voltage of the snubber capacitor 4 fluctuates, the voltage of the recovery capacitor 16 rises only up to 1.5V. Further, when the voltage of the snubber capacitor 4 fluctuates at the system frequency, a current of 100 A cannot normally flow, and it can be considered that the voltage of the recovery capacitor 16 remains almost zero volt.

As described above, the recovery capacitor 16 cannot be initially charged simply by turning on the circuit breaker 43 and connecting the power converter and the power system 44. Therefore, in the present embodiment, power is not supplied or consumed to the power system 44 by switching the GTO1 of the power converter so that the output voltage of the power converter and the system voltage are completely opposed. Charging the recovery capacitor 16 as described above. In order to switch the GTO 1 in this manner, the power converter may be controlled so that the output voltage of the power converter and the system voltage become exactly the same voltage. For example, PWM
When the power converter is operated using the above, the modulation factor may be set so that the output voltage becomes the same as the system voltage. FIG. 15 is a diagram illustrating an example of the PWM according to the fourth embodiment of the present invention. It is assumed that the PWM modulation rate shown in FIG. 15 is set so that the output voltage of the power conversion device faces the system voltage. It is also assumed that the PWM carrier frequency is the same as during normal operation.

Next, a method of starting the power converter shown in FIG. 14 will be described. Here, as the timing for starting the initial charging of the recovery capacitor 16, it is assumed that the rising edge of the gate signal pulse is used as in the third embodiment. In this case, the following attention is required.

First, consider the case where the initial charging of the recovery capacitor 16 is started at the timing of time t1 shown in FIG. FIG. 16A shows the time t1 of the PWM shown in FIG.
FIG. 16B is a diagram of a gate signal actually given to each GTO when the initial charging of the recovery capacitor 16 is started at time t1. When a gate signal as shown in FIG. 16B is given to each phase, the anode reactor 1 in the V phase within (t2-t1) time.
4 cannot be reset, V turned on at time t2.
GTO1 of the upper arm in the phase may be subject to high di / dt. Therefore, it is necessary not to start the initial charging of the recovery capacitor 16 at such a timing.

Next, consider the case where the initial charging of the recovery capacitor 16 is started at a timing t3 different from the timing of the gate signal shown in FIG. FIG.
FIG. 17A is an enlarged view of the vicinity of time t3 of the PWM shown in FIG. 15, and FIG. 17B is a diagram of a gate signal actually given to each GTO when the initial charging of the recovery capacitor 16 is started at time t3. It is. When the gate signal as shown in FIG. 17B is given to each phase, the time from the first turn-on operation to the next turn-on operation (t4−t)
3), (t5-t3) and (t6-t3), the minimum is the U-phase time (t4-t3) used for the initial charging start timing of the recovery capacitor 16. And
This time is longer than a series of operation times associated with the turn-on operation of the upper arm GTO 1 in the U phase, that is, the time until the lower arm snubber capacitor 4 charges to E / 4 volts and the anode reactor 14 resets in the U phase. There must be.

When the output terminal 19 of the power converter is connected to the power system 44, the voltage of the snubber capacitor 4 changes in synchronism with the system voltage as described above. The voltage of the snubber capacitor 4 of the second arm differs depending on the timing at which the initial charging of the recovery capacitor 16 is started. Therefore, when the initial charging of the recovery capacitor 16 is started at a certain timing, for example, if the GTO 1 of the upper arm is turned on, the snubber capacitor 4 of the lower arm charges to E / 4 volts and the anode reactor 14 is reset. The time also differs depending on the voltage of the snubber capacitor 4 of the lower arm at that timing.

The longest series of operation times associated with the turn-on operation of the GTO 1 when the initial charging of the recovery capacitor 16 starts is that the snubber capacitor 4 is charged from zero volts to E / 4 volts, and then the anode reactor 14 Is reset. This longest time is T2
Then, in the power converter shown in FIG.
Is obtained by Expression (6). Therefore, for example, when the initial charge is performed using the timing such as the time t3 shown in FIG. 15, only when (t4−t3)> T2,
If it is set in advance so that the initial charging of the recovery capacitor 16 is started, (t6-t3)> (t5-
Since t3)>(t4−t3)> T2, the anode reactor 14 is necessarily reset by the next turn-on operation.

{Π / (2ω ₁ )} + {π / (2ω ₂ )} (6)

Now, instead of the timing at time t1 shown in FIG. 15, the timing as at time t3, for example, as shown in FIG.
At the timing of time t7 shown in FIG.
It is assumed that the initial charging start timing is set. In this case, a minimum width pulse at the currently set modulation rate is output in the V phase from t7. Even in such a case, the time T3 until the GTO1 is turned on in the upper arm, which is the next turn-on operation of the V phase, is T3.
> T2 must be established. Conversely, if the initial charging start timing is set as described above, and if it is possible to start the initial charging of the recovery capacitor 16 at the timing at which the minimum width pulse is output, at other timings It can also be said that it is possible to start.

In the PWM, the minimum width pulse output for the modulation rate can be calculated in advance. Further, since the upper and lower arm short circuit prevention time Td is also predetermined, T3 can be obtained from these. That is, T3 for the modulation rate can be obtained in advance.

Here, an example of the characteristics of T3 with respect to the PWM modulation rate will be described. FIG. 18 is a diagram illustrating an example of a characteristic of T3 with respect to a PWM modulation rate. Here, the carrier frequency of the PWM was 450 Hz, and Td was 40 μs.

When the system voltage is high, the PWM modulation rate becomes large, so that T3 becomes short as shown in FIG. As described above, when T3 <T2, the anode reactor 14 may not be able to be reset before the next GTO1 turns on. That is, in this example, it is understood that the initial charging of the recovery capacitor 16 cannot be started when the system voltage is such that the modulation factor is 0.8 or more. If such characteristics are grasped in advance, the maximum value of the system voltage at which the initial charging of the recovery capacitor 16 can be started, that is, the maximum value of the PWM modulation rate can be set.

In the above example, the system voltage is high and P
When the modulation rate of the WM is large, the initial charging of the recovery capacitor 16 is not started at the timing of T3 <T2. However, even with such a modulation rate, if there is another timing that can secure T2 or more, the initial charging of the recovery capacitor 16 can be started from that timing.

More specifically, since T3 <T2 at the timing at time t7 shown in FIG. 15, even when the initial charging of the recovery capacitor 16 cannot be started, if the initial charging is started from the timing at time t8. It may be possible to start charging. However, at this time, it is necessary to grasp the maximum value of the modulation rate at which the initial charging of the recovery capacitor 16 can be started also at the timing at the time t8.

In the above description, the PWM carrier frequency is assumed to be the same as in the normal operation. However, if the carrier frequency is lowered at the same modulation rate, the above-mentioned time T3 becomes longer. Therefore, when the carrier frequency at the time of the initial charging of the recovery capacitor 16 is the same as that during the normal operation, the timing at which the initial charging could not be started may be started at a low carrier frequency. . That is, if the PWM carrier frequency is lowered only during the initial charging of the recovery capacitor 16, the initial charging can be started even when the modulation rate is high.

After the recovery capacitor 16 is initially charged to a predetermined voltage according to the method described above, the operation is switched to a normal operation for supplying and consuming power to the power system 44.

According to the method described here, the recovery capacitor 16 can be initially charged without affecting the system side, and the power converter can be started safely and reliably.

Embodiment 5 FIG. 19 is a diagram showing a time chart of a start-up method of the power conversion device according to the fifth embodiment of the present invention. In the figure, Vth1 is a voltage at which the recovery capacitor 7 can supply energy to the power supply of the gate drive circuit 12 and the power supply of the energy regeneration circuit 11,
Vrg1 is a regenerative operation start voltage of the energy regenerative circuit 11, Vth2 is a voltage at which the recovery capacitor 16 can supply power to the energy regenerative circuit 18, Vrg2 is a regenerative operation start voltage of the energy regenerative circuit 18, and Vth3
Is an initial charging voltage not lower than Vth2 and not higher than Vrg2.

In the first to fourth embodiments, the method of starting the power converter from the state where the voltage of the DC capacitor 41 is zero volt has been described. On the other hand, in the present embodiment, the power conversion device that starts according to the method described above and then performs the normal operation is stopped once, and after a certain time,
Consider a case where normal operation is performed again. In the present embodiment, it is assumed that the voltage of DC capacitor 41 is always kept constant.

When the normal operation is stopped from the state where the normal operation is performed, the supply of energy to the recovery capacitors 7 and 16 accompanying the switching of the GTO 1 during the normal operation is stopped. However, even in this case, the gate drive circuit 12 and the energy regeneration circuit 1
Since no-load power continues to be supplied to the power supply 1 and the recovery capacitor 16 to the power supply of the energy regeneration circuit 18, the voltage of each recovery capacitor decreases. However, since the voltage of the DC capacitor 41 always keeps E volt, the recovery capacitor 7 is charged through the path 5 shown in FIG. For this reason, the voltage of the recovery capacitor 7 becomes a constant value where the above-mentioned no-load power and the power supplied through the path 5 shown in FIG. But,
Since power is not supplied to the recovery capacitor 16, the voltage of the recovery capacitor 16 gradually decreases, and this voltage becomes Vt.
When h2 or less, the control circuit of the energy regeneration circuit 18 stops.

In order to resume the normal operation from such a state, first, the recovery capacitor 16 is initially charged, the voltage value Vth2 necessary for operating the control circuit of the energy regenerating circuit 18 is secured, and the anode is further charged. Voltage value Vt determined by restriction of reset time of reactor 14
It is necessary to secure h3. Therefore, when a command to restart the normal operation is issued, the recovery capacitor 16 is initially charged, and then the normal operation is performed. Therefore, the normal operation cannot be resumed simultaneously with the command.

Therefore, in the present embodiment, as shown in the time chart of FIG. 19, when the voltage of the recovery capacitor 16 becomes equal to or lower than Vth3 during the period in which the normal operation is stopped, Initial charging as described in 1-4 is performed. By doing so, the power conversion device can always maintain a state in which normal operation can be restarted, so that normal operation can be restarted simultaneously with a command at any time.

In this embodiment, the method of initial charging with the circuit breaker 43 turned on has been described. However, when the recovery capacitor 16 can be charged to a predetermined voltage while the circuit breaker 43 is open. The initial charging method of the recovery capacitor 16 as described in the third embodiment may be applied.

Embodiment 6 FIG. In the first to fifth embodiments, the starting method of the power converter having the circuit configuration shown in FIG. 1 has been described. However, as long as the power conversion device recovers the stored energy of the anode reactor 14 to the recovery capacitor 16 and regenerates the energy to the DC power supply side 100 by the energy recovery circuit 18, even if the GTO is not connected in series, the recovery capacitor 16 The initial charging method is basically the same. Therefore, it is possible to apply the above-described method for starting the power converter to a power converter having another circuit configuration.

FIG. 20 is a diagram showing a power converter according to the sixth embodiment of the present invention, which is a diagram of a power converter that regenerates energy stored in a snubber capacitor and an anode reactor to a DC power supply. In the figure, reference numerals 1a and 1h denote self-extinguishing semiconductor switching elements (GTO1a, GTO1).
h) 2a, 2h are freewheel diodes connected in anti-parallel to GTO1a, GTO1h, 3a, 3h are connected in parallel to GTO1a, GTO1h, and are composed of a series circuit of snubber capacitors 4a, 4h and snubber diodes 5a, 5h. Snubber circuits 10a and 10h are initial charging resistors, 12a and 12h are gate drive circuits for driving GTO1a and GTO1h, and 14a and 14b are anode reactors.

21a and 21h are feeding capacitors, 22
a and 22b are recovery capacitors, 23a and 23h are recovery diodes, and 24a and 24b are recovery capacitors 22a and 2b.
2b is an energy regenerating circuit that regenerates the energy recovered in 2b to the DC power supply side 100. Also, 25a, 25h
Is a resonance capacitor, 26a and 26h are resonance reactors,
27a, 27h and 28a, 28h are diodes. The internal configuration of 30b to 30d is 30a, 30e to
Since the internal configuration of 30g is the same as that of 30h, the description is omitted. 31a is a G composed of 30a to 30d.
An upper arm in which four TOs are connected in series, 31b is 30
e is a lower arm in which four GTOs composed of e to 30h are connected in series.

In the power converter shown in FIG. 20, the energy stored in the snubber capacitor 4 of the upper arm 31a and the energy stored in the anode reactor 14a are recovered by the recovery capacitor 22a. The energy stored in the reactor 14b is recovered by the recovery capacitor 22b. That is, in the power converter shown in FIG. 1, the energy which is divided and recovered into the recovery capacitor 16a and the recovery capacitor 7 of the upper arm 31a is collectively stored in the recovery capacitor 22a in the power converter shown in FIG. Collected. Also, the role of the recovery reactor 8 in the power converter shown in FIG. 1 is played by the anode reactor 14 in the power converter shown in FIG.

In the power converter shown in FIG. 20,
The energy of the power supply of the gate drive circuit 12 is supplied from the power supply capacitor 21. In the power converter shown in FIG. 1, a part of the energy stored in the snubber capacitor 4 recovered by the recovery capacitor 7 is transferred to the gate drive circuit 12.
Is supplied for power supply. On the other hand, in the power converter shown in FIG. 20, energy is supplied to the power supply capacitor 21 by the capacitor 25 or the resonance reactor 26 without using the energy stored in the snubber capacitor 4 for the power supply of the gate drive circuit 12. I have.

Although the circuit operation is not described in detail, the route 1 shown in FIG. 2A in the power converter shown in FIG.
20 corresponds to the path 9 shown in FIG. 21A. However, as described above, in the power converter shown in FIG.
Since the energy stored in the snubber capacitor 4 is collectively recovered by the recovery capacitor 22a, the discharge path of the upper arm 31a snubber capacitor 4 when the GTO of the upper arm 31a is turned on is the same as the path 10 shown in FIG. Become. Hereinafter, the route 11 shown in FIG. 22A corresponds to the route 2 and the route 7 shown in FIGS. 2B and 5A. In other words, it can be seen that the power converters shown in FIGS. 1 and 20 are equivalent with respect to the stored energy recovery operation of the anode reactor 14 and the current reset time.

The energy supplied to the power supply of the gate drive circuit 12 before the GTO starts switching is determined by the power converter shown in FIG.
The current flowing through the path 5 shown in FIG. On the other hand, in the power converter shown in FIG.
The current is secured by the current flowing through the path 12 shown in FIG.
That is, it can be seen that the power converters shown in FIGS. 1 and 20 are equivalent with respect to the power supply of the gate drive circuit when the DC capacitor is charged from zero volt to a predetermined DC voltage.

As described above, the starting method of the power converter described in the first to fifth embodiments can be applied to power converters other than those shown in FIG.

[0106]

According to the first aspect of the present invention, the starting method of the power converter can charge the capacitor initially to a predetermined voltage before starting the normal operation, and at the same time, use the energy stored in the capacitor in excess. It can regenerate to the DC power supply.

In the method for starting the power converter according to the second aspect of the present invention, the recovery capacitor can be initially charged to a predetermined voltage via the initial charging resistor before starting the normal operation. Further, the energy excessively stored in the recovery capacitor can be regenerated to the DC power supply unit or supplied to the gate of the self-extinguishing type switching element by a gate drive circuit (can be used together).

According to a third aspect of the present invention, in the starting method of the power converter, the energy of the anode reactor recovered by the capacitor is regenerated to the DC power supply, and the energy of the snubber capacitor recovered by the recovery capacitor is supplied to the DC power supply. It can be regenerated or supplied to the gate of a self-extinguishing type switching element by a gate drive circuit (can be used together).

According to a fourth aspect of the present invention, in the starting method of the power converter, a part of the energy stored in the recovery capacitor is supplied as a driving power source for the recovery energy regenerating circuit, and thereafter, the energy is excessively stored in the recovery capacitor. Energy can be regenerated to the DC power supply.

According to a fifth aspect of the invention, there is provided a method of starting a power converter, wherein a part of energy stored in a recovery capacitor is supplied as a driving power source for a gate drive circuit, and thereafter, an excess amount of energy is stored in the recovery capacitor. Energy can be supplied to the gate of the self-extinguishing type switching element.

According to a sixth aspect of the invention, there is provided a method for starting a power converter, comprising securing a drive power source for a recovered energy regenerating circuit or a drive power source for a gate drive circuit, and simultaneously storing energy excessively stored in a recovery capacitor in a direct current. It can regenerate to the power supply.

According to a seventh aspect of the present invention, in the method of starting a power conversion device, a part of the energy stored in the capacitor is supplied as a driving power source for the energy regenerating circuit, and the energy excessively stored in the capacitor thereafter is supplied. It can regenerate to the DC power supply.

In the method for starting the power converter according to the eighth aspect of the present invention, the drive power for the energy recovery circuit is ensured, and at the same time, the energy excessively stored in the capacitor can be recovered to the DC power supply.

According to a ninth aspect of the present invention, in the starting method of the power converter, the anode reactor is reset within a predetermined time in any state assumed when the power converter is normally operated. Can be higher than the voltage that can be achieved. Therefore, immediately after the normal operation is started, even if the reset time of the anode reactor becomes the strictest, the anode reactor is surely reset. Therefore, the di / dt applied to the self-extinguishing type switching element is designed. The value is suppressed according to the value, and the self-extinguishing type switching element can be safely driven.

According to a tenth aspect of the present invention, the anode reactor can be reset before the self-extinguishing type switching element is turned on. Therefore, at the time of turn-on, di / dt applied to the self-extinguishing type switching element is suppressed as designed, and self-extinguishing type switching can be safely driven.

According to the method of activating the power converter according to the eleventh aspect, the voltage of the capacitor can always be maintained at a predetermined voltage or higher. Therefore, the normal operation can be immediately started at any timing.

According to a twelfth aspect of the present invention, there is provided a method for starting a power converter, wherein power is not supplied or consumed between the power converter and a load, that is, any one of a capacitor and a recovery capacitor can be used without affecting the load. One or both can be initially charged to a predetermined voltage.

According to a thirteenth aspect of the present invention, there is provided a method for starting a power converter, wherein power is not supplied or consumed between the power converter and a load, that is, any one of a capacitor and a recovery capacitor can be used without affecting the load. One or both can be initially charged to a predetermined voltage.

According to a fourteenth aspect of the present invention, the self-extinguishing type switching element is switched so that the line voltage of the power system load and the line voltage of the output of the power converter become equal. Therefore, power is not supplied or consumed between the power conversion device and the power system load, that is, one or both of the capacitor and the recovery capacitor are initially charged to a predetermined voltage without affecting the power system as a load. can do. In addition, when the self-extinguishing type switching element is switched, initial charging can be prevented from starting when the element is likely to be destroyed due to high di / dt when turned on.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a power conversion device according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation of the power converter shown in FIG.

FIG. 3 is a diagram for explaining the operation of the power converter shown in FIG.

FIG. 4 is a diagram for explaining the operation of the power converter shown in FIG.

FIG. 5 is a diagram for explaining the operation of the power converter shown in FIG.

FIG. 6 is a diagram showing a power conversion device according to the first embodiment of the present invention.

FIG. 7 is a time chart illustrating a method of activating the power conversion device illustrated in FIG. 6;

FIG. 8 is a diagram showing a phase voltage at which the line voltage of the power converter shown in FIG. 6 becomes zero volt.

FIG. 9 is a diagram showing a gate signal of the power conversion device shown in FIG.

FIG. 10 is a diagram showing characteristics of a reset time of an anode reactor with respect to an initial voltage of a recovery capacitor.

FIG. 11 is a time chart illustrating a method of starting the power conversion device according to the second embodiment of the present invention.

FIG. 12 is a diagram showing a power conversion device according to a third embodiment of the present invention.

FIG. 13 is a diagram showing a gate signal of the power conversion device shown in FIG.

FIG. 14 is a diagram showing a power conversion device according to a fourth embodiment of the present invention.

FIG. 15 is a diagram showing a gate signal of the power converter shown in FIG.

FIG. 16 is an enlarged view of the gate signal shown in FIG.

17 is an enlarged view of the gate signal shown in FIG.

FIG. 18 is a diagram illustrating characteristics of a T3 time with respect to a PWM modulation rate.

FIG. 19 is a time chart illustrating a method of starting the power conversion device according to the fifth embodiment of the present invention.

FIG. 20 is a circuit configuration diagram of a power conversion device according to a sixth embodiment of the present invention.

FIG. 21 is a diagram illustrating an operation of the power conversion device illustrated in FIG.

FIG. 22 is a diagram illustrating an operation of the power conversion device illustrated in FIG.

FIG. 23 is a diagram showing a conventional power converter.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Self-extinguishing semiconductor element 2 Freewheel diode 3 Snubber circuit 4 Snubber capacitor 5 Snubber diode 6 Energy recovery circuit 7 Recovery capacitor 8 Recovery reactor 9 Recovery diode 10 Initial charge resistance 11 Energy regeneration circuit 12 Gate drive circuit 13 Optical fiber 14 Anode Reactor 15 Energy recovery circuit 16 Recovery capacitor 17 Recovery diode 18 Energy recovery circuit 19 Output terminal 21 Power supply capacitor 22 Recovery capacitor 23 Recovery diode 24 Energy recovery circuit 25 Resonance capacitor 26 Resonant reactor 27 Diode 28 Diode 31a Upper arm 31b Lower arm 40 Phase 41 DC capacitor 42 Motor 43 Circuit breaker 44 Power system 50 Snubber resistor 51 Reset resistor 52 Reset diode

Claims (14)

[Claims] 1. A DC power supply, a self-extinguishing type switching element connected in series between both poles of the DC power supply, a diode connected in anti-parallel to the switching element, and a parallel connection to the switching element. A snubber circuit comprising a series body of a connected snubber capacitor and a snubber diode, an anode reactor connected in series with the switching element between both poles of the DC power supply unit, and a capacitor connected between terminals of the anode reactor and A power having a phase having an energy recovery circuit composed of a series body of diodes, and an energy regeneration circuit connected between the capacitor and the DC power supply for regenerating energy stored in the capacitor to the DC power supply. In a method for activating a power conversion device for activating a conversion device, the power conversion device Prior to the start of normal operation, an energy storage step of causing a current to flow in a closed loop formed by the anode reactor and the energy recovery circuit by switching the switching element and storing energy in a capacitor of the energy recovery circuit, An energy regeneration step of regenerating the energy stored in the capacitor to the DC power supply unit by the energy regeneration circuit. 2. A DC power supply, a self-extinguishing type switching element connected in series between both poles of the DC power supply, a diode connected in anti-parallel to the switching element, and a diode connected in parallel with the switching element. A snubber circuit comprising a series body of a connected snubber capacitor and a snubber diode, an anode reactor connected in series with the switching element between both poles of the DC power supply unit, and a capacitor connected between terminals of the anode reactor and An energy recovery circuit composed of a series body of diodes, an energy regeneration circuit connected between the capacitor and the DC power supply for regenerating energy stored in the capacitor to the DC power supply, and an energy recovery circuit in parallel with the switching element. A series body of a connected initial charging resistor and a recovery capacitor, and A recovery energy regenerating circuit connected between the capacitor and the DC power supply for regenerating the energy recovered by the recovery capacitor to the DC power supply, and the recovery capacitor connected between the recovery capacitor and the gate of the switching element; A method for starting a power converter having a phase having one or both of a gate drive circuit and a gate drive circuit for supplying energy recovered to the gate to the gate, comprising: Before, a step of storing energy in the recovery capacitor via the initial charging resistor, a first recovery energy recovery step of recovering the energy stored in the recovery capacitor to the DC power supply unit by a recovery energy recovery circuit, and Gate-dried energy recovered in the recovery capacitor One or both of the second recovered energy regeneration processes provided to the gate by the sub-circuit;
After the recovered energy regeneration step, an energy storage step of causing a current to flow in a closed loop formed by the anode reactor and the energy recovery circuit by switching the switching element to store energy in a capacitor of the energy recovery circuit; and An energy regeneration step of regenerating the energy stored in the DC power supply unit by an energy regeneration circuit. 3. The process of accumulating energy includes accumulating energy in a recovery capacitor and accumulating energy in a snubber capacitor via an initial charging resistor before starting normal operation of the power conversion device. After the energy regeneration process, by switching a switching element, a current flows through a closed loop composed of an anode reactor and an energy recovery circuit to store energy in a capacitor of the energy recovery circuit and to store energy stored in the snubber capacitor. 3. The method according to claim 2, further comprising the step of accumulating the power in the recovery capacitor. 4. A first recovered energy regenerating step includes supplying energy of a recovery capacitor to the recovered energy regenerating circuit to drive the recovered energy regenerating circuit, and obtaining a driving power source for the recovered energy regenerating circuit. ,
The method according to claim 2 or 3, wherein the energy of the recovery capacitor is regenerated to the DC power supply unit by the recovery energy regeneration circuit. 5. The second recovered energy regenerating step includes supplying energy of a recovery capacitor to the gate drive circuit to drive the gate drive circuit, and obtaining a drive power supply for the gate drive circuit. 5. The method according to claim 2, wherein energy of a capacitor is supplied to a gate by the gate drive circuit. 6. 6. The voltage of the recovery capacitor is equal to or higher than the drive voltage of the recovery energy regeneration circuit or the drive voltage of the gate drive circuit, and is equal to or lower than the regeneration operation start voltage of the recovery energy recovery circuit. 6. The method for activating a power conversion device according to claim 5. 7. The energy regenerating step includes supplying energy of a capacitor to the energy regenerating circuit to drive the energy regenerating circuit, and obtaining a driving power source for the energy regenerating circuit. The method according to any one of claims 1 to 6, wherein the DC power supply is regenerated by a regenerative circuit. 8. The power converter according to claim 1, wherein the voltage of the capacitor is equal to or higher than the driving voltage of the energy regenerating circuit and equal to or lower than the regenerative operation start voltage of the energy regenerating circuit. How to start. 9. The capacitor according to claim 1, wherein the voltage of the capacitor is equal to or higher than a voltage at which the anode reactor is reset within a predetermined time and equal to or lower than a regenerative operation start voltage of the energy regenerating circuit. Method for activating the power converter. 10. The energy storage process according to claim 1, wherein the application time of the gate signal for driving the switching element is set to be longer than the time until the anode reactor is reset. A method for activating the power converter according to claim 1. 11. The method according to claim 1, wherein in the energy storing step, energy is stored in the capacitor when a voltage of the capacitor is equal to or lower than a predetermined voltage. . 12. The starting method of a power converter for starting a power converter according to claim 1 or 2, comprising a plurality of phases connected in parallel to a DC power supply unit. The method according to any one of claims 1 to 11, wherein output line voltages output from a plurality of phases of the converter are set to zero volts. 13. A starting method of a power converter for starting a power converter according to claim 1 or 2, comprising a plurality of phases connected in parallel to a DC power supply unit. The output line voltage output from a plurality of phases of the converter is set to be equal to the line voltage of a power system load connected to an output terminal of the power converter. A method for activating a power conversion device according to claim 1. 14. The method according to claim 13, wherein the switching element is switched according to a line voltage of a power system load connected to an output terminal of the power converter.