JPH0258872B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of controlling a power regeneration circuit using a self-extinguishing element such as a transistor or a GTO (gate turn-off thyristor).

[Conventional technology]

FIG. 3 is a block diagram showing the configuration of a conventional voltage source inverter device. In this figure, 1 is a three-phase AC power supply, 2 is a current-limiting reactor, 3 is a current detector, 4 is a regeneration bridge (hereinafter referred to as reverse RF) consisting of six transistors SU to SZ, and 5 is 6
6 is a smoothing electrolytic capacitor, and 7 is an inverter consisting of 6 transistors and a feedback diode connected in antiparallel to each of the transistors. , 8 is a motor, 9 is a deviation detection point that compares the output of the current detector 3 and the current command and outputs the difference voltage, and 10 is a control circuit that controls on/off each transistor SU to SZ of the inverse RF 4. be.

In such a configuration, when the motor 8 is driven from its load side, it acts as a generator, and the generated power is regenerated to the DC side via the inverter 7, charging the electrolytic capacitor 6 and increasing the DC voltage. . In order to avoid this voltage increase, there are methods such as discharging the power through a resistor or regenerating it to the AC power supply 1, but this inverter device uses a regeneration method.

That is, as shown in FIG. 4, in synchronization with the phase voltages U to W of the AC power source 1, the transistors
Sequentially conduct the SZ by 120° (or 180°) in electrical angle,
The DC power supplied from the inverter 7 is converted back into AC power and regenerated to the AC power supply 1 side.

However, in the above-mentioned regenerative circuit, the reactor 2 is the only thing that limits the magnitude of the regenerative current while the transistors SU to SZ are conducting, so either a separate current control device is provided or the transistors SU to SZ are Turn on SZ in shorter cycles/
It was controlled off and the magnitude of the average current was adjusted.

In this case, the method of controlling the current with a conduction period of 120° has a lower regenerative ability than the method of conducting 180° even if elements with the same current rating are used.
180° conduction was established, and each phase was independently controlled on/off so that the regenerative current flowing through reactor 2 matched the current command.

[Problem that the invention seeks to solve]

By the way, when each phase is independently controlled on/off with 180° conduction, there is a problem in that a line short circuit L is formed as shown in FIG. 5C, and the regeneration efficiency is reduced.

This problem will be explained below, taking as an example the case where the phase voltage U is the highest and the phase voltage W is the lowest. In this case, as shown in Figure 5 A and B, if the transistor SU or SZ is conductive, these transistors will keep the voltage across the diodes DU and DZ almost 0, while the diodes DV, DW or DX, Reverse bias DY. Therefore, these diodes are cut off, the positive RF 5 is disconnected from the AC power supply 1, and no short circuit occurs in the power supply.

However, during 180° conduction and independent on/off control of each phase, as shown in Figure 5C, there also occurs a period in which transistors SU and SZ are off and SV is on, and at this time, the diode DU and transistor SV becomes conductive and a power supply short circuit L is formed. As a result, a problem arises in that the power regeneration period is reduced and the utilization efficiency of the regeneration circuit is reduced.

This invention attempts to solve the above problems.

[Means for solving problems]

In order to solve the above problems, this invention configures the reverse RF for regeneration with self-extinguishing elements, and the voltage between 0° and 60° and between 120° and 180° out of the 180° width of each phase voltage is The self-extinguishing element is controlled on/off to control the current, and the self-extinguishing element is maintained in the ignited state between 60° and 120°.

[Effect]

According to the above method, between 60 degrees before and after the instantaneous value of each phase voltage is the highest and 60 degrees before and after the lowest instantaneous value (that is, between 60 degrees and 120 degrees above), the The self-extinguishing element turns on. As a result, the self-extinguishing elements associated with the phase voltage with the largest absolute value are turned on one after another, and the self-extinguishing elements that have been turned on are connected to diodes whose common terminals are connected (for example, the transistor SU in Figure 1 is turned on). In this case, the diodes DU to PW connected thereto are all cut off (in the example above, the diode DU is at zero bias, and DV and DW are reverse biased and cut off). Therefore, the positive RF consisting of diodes DU to DZ is disconnected from the AC power supply,
Line-to-line short circuits of AC power supplies do not occur. Also,
During electrical angle periods of 0° to 60° and 120° to 180°, the self-extinguishing element is controlled on/off so that the current waveform conforms to the command, so two-phase current control is always performed, and all Since the current of the remaining ignited phases is the sum of the above-mentioned two-phase currents, three-phase current control can be performed after all.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of main parts of an embodiment in which the present invention is applied to the current source inverter device shown in FIG. 3, and parts corresponding to those in FIG. 3 are given the same reference numerals. be. This embodiment differs from the conventional device shown in FIG. 3 in the configuration of the control circuit 10a, and FIG. 1 shows the control circuit for the transistor SU. Note that similar control circuits are also connected to the other transistors SV to SZ.

In this figure, 11a to 11c are current commands for each phase, which use inverted waveforms of phase voltages U, V, and W. Comparators 12a to 12c output a rectangular wave that is at the "H" level for a period of 180° on the positive side of each phase voltage U to W, and the comparators 12b,
12c is supplied to the OR gate 13, and the second
A signal S1 shown in FIG. 4 is generated.

On the other hand, the output of the deviation detection point 9, that is, the value obtained by subtracting the actual U-phase current from the U-phase current command, is inverted by the inverter 14, and the signal S shown in FIG.
It becomes 2. This signal S2 becomes "H" level when the actual current is larger than the current command, and the signal S
1 and is supplied to the NAND gate 15. The NAND gate 15 outputs a signal S4 that becomes "H" level when both or one of the signals S1 and S2 is "L" level. Then, the output signal S3 of the comparator 12a (FIG. 2D) and the signal S4 (FIG. 2E) are supplied to the AND gate 16, and the signal S5 shown in FIG.

This signal S5 becomes "H" level between 0° and 60° and between 120° and 180° of the positive side of the U phase when the actual current is smaller than the current command (as shown in Figure 2). 18), and maintains the "H" level between 60° and 120° (19 in the figure). Therefore, the signal S
5 is supplied to the base of the transistor SU through the amplifier 17, the transistor SU is controlled on/off to perform current control between 0° and 60° and 120° and 180°, and current control is performed between 60° and 180°. Transistor between 120°
SU remains on. Further, the other transistors SV to SZ are similarly controlled by the control signals shown in FIG.

According to the above configuration, as shown in Fig. 2, transistor SY is on (all firing) between 0° and 60° of the U-phase voltage, SU and SW are on/off controlled, and between 60° and 120°. Between 120° and 180°, transistor SU is fully turned on, SY and SZ are on/off control, and between 120° and 180°, transistor SZ is on.
is fully fired, and SU and SV are controlled on/off. Here, for example, during the 60° period when the transistor SU is fully turned on, the current flowing to the V phase and W phase is independently controlled by turning on/off the transistors SY and SZ so that it matches the current command. Ru. Moreover, at this time, since the current flowing in the U phase is the sum of the currents flowing in the V phase and the W phase, three-phase current control is performed after all. This also applies when the other transistors are fully fired.

Also, between 60° and 120° above, the transistor SU
is on and the U-phase voltage is the highest, all diodes DU to DW are cut off, and the positive RF
5 is separated from the AC power source 1. As a result, formation of a power supply short circuit L as shown in FIG. 5C can be prevented.

In the above embodiment, the inverse RF 4 is composed of transistors SU to SZ, but the present invention is not limited to this, and any self-extinguishing element such as a GTO can be similarly used.

〔Effect of the invention〕

As explained above, this invention
The RF is configured with a self-extinguishing element, and current control is performed by controlling the self-extinguishing element on/off between 0° to 60° and 120° to 180° out of the 180° width of each phase voltage. , 60° to 120°, the self-extinguishing element is maintained in the ignited state, so the following effects can be achieved.

(1) Power regeneration can be performed efficiently because power supply short circuits do not occur.

(2) Current control can be performed using only the control circuit, and there is no need to add another current control circuit. In addition, the regenerative current has a width of 180°, which has a greater regenerative ability than a width of 120°.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the main parts of an embodiment in which the present invention is applied to a current source inverter device, FIG. 2 is a waveform diagram showing waveforms of each part of the embodiment, and FIG.
The figure is a block diagram showing the configuration of a conventional current source inverter device, and Figure 4 shows the phase voltages U to W in the same device.
FIG. 5 is a diagram showing the relationship between on/off control of the transistors SU to SZ, and FIG. 5 is a diagram for explaining the reason why a power supply short circuit occurs. 1... Three-phase AC power supply, 4... Reverse RF (reverse rectifier), 5... Positive RF (positive side rectifier), DU~DZ...diode, SU~SZ...transistor (self-extinguishing element).

Claims (1)

[Claims] 1 A three-phase bridge is constructed by an anti-parallel circuit of a diode and a self-extinguishing element, and this three-phase bridge is connected to the output end of a three-phase AC power supply, and during power running, the positive side rectifier consisting of the diode is operated. In a power regeneration circuit that supplies DC power to the load side, and at the time of regeneration, operates a reverse rectifier consisting of the self-arc-extinguishing element to regenerate feedback power to the AC power supply, the voltage of each phase of the AC power supply is Current control is performed between 0° to 60° and 120° to 180° of the ° width.
A method of controlling a power regeneration circuit characterized by fully firing between 60° and 120°.