JPS60190176A - Power regenerative apparatus - Google Patents

Abstract

PURPOSE:To decrease the peak value of a phase current at the regenerative time by inserting a resistor in every phase in a connection path of an AC power source and a photocoupler, thereby altering the timing of turning ON or OFF the photocoupler. CONSTITUTION:Resistors (r) are respectively inserted into connection paths of the phases U, V, W of an AC power source 4 and photocouplers P1-P6 which form a phase voltage detector 9. The rectified voltage of a rectifier 1 is charged in a smoothing condenser 5, the DC voltage of the condenser 5 is converted by an inverter 6 into an AC voltage, and supplied to an AC load 7. The timings of turning ON or OFF the photocouplers P1-P6 are altered by connecting the resistors (r) to decrease the peak value of the phase current at the regenerative time.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to a power regeneration device, in particular, to supply power from an AC power source to a smoothing capacitor as a DC power source, and in the event of a power outage, load fluctuation, etc., the power on the DC power source is transferred to the AC power source. The present invention relates to a power regeneration device that regenerates power from a smoothing capacitor serving as a DC power source to an AC power source when the potential becomes high on the side.

[Prior art]

FIG. 1 is a circuit diagram of a conventional power regeneration device. In FIG. 1, 1 is a rectifier circuit configured in a bridge shape with a plurality of diodes D1 to D6, and 2 is a power transistor or thyristor capable of forced commutation, for example. Electric valves B1 to B6 (
This is a regeneration circuit configured in a bridge type (represented by a switch in the drawing), and these two circuits 1 and 2 are connected in parallel to each other to form a rectification and regeneration circuit. 3 is rectifier circuit 1
And the AC side of the regeneration circuit 2 is connected to an AC power source (the illustrated example is U, V
.

(3-phase AC power source of W) 4 is an AC reactor installed in the connection path connected to 4, 5 is a smoothing capacitor connected in parallel to the DC side of the rectifier circuit 1 as a DC power supply, 6 is a smoothing capacitor 5 that converts the DC voltage into an AC voltage. The converting inverter circuit 7 is an AC load connected to the inverter circuit 6. 8 is a phase voltage detection circuit constructed by connecting a plurality of photocouplers P1 to P6 and diodes D7 to D12 in antiparallel to each other to form a bridge circuit, and connecting a resistor R in parallel to this bridge circuit; 9Vi to the electric valve; This is an electric valve drive circuit that sequentially supplies drive signals, and for example, as shown in FIG. 2, it is composed of an inverting buffer that receives a signal from a photocoupler of the phase voltage detection circuit 8 as input.

The conventional power regeneration device is configured as described above, and the smoothing capacitor 5 is charged with the rectified voltage of the rectifier circuit l. Then, the DC voltage of the smoothing capacitor 5 is converted into an AC voltage by an inverter circuit 6 and supplied to an AC load 7.

On the other hand, since the electric valves B1 to B6 of the regeneration circuit 2 are sequentially turned on by the drive signal from the electric valve drive circuit 9, if the charging voltage of the smoothing capacitor 5 becomes higher than the AC power supply voltage due to a power outage, load fluctuation, etc. Electric power is regenerated from the smoothing capacitor 5 to the AC power source 4 through the turned-on electric valve.

In this case, in the phase voltage detection circuit 8, the photocouplers corresponding to the maximum and minimum phase voltages are turned on. That is, as shown in FIG. 3, the three-phase voltages vo and Vv.

In the waveform of Vw, in the 6th section I, the phase voltage U phase is the maximum and the W phase is the minimum, and the photocoupler Pi is turned on. As a result, the electric valve of the regeneration circuit 2 turns on the AC power source 4.
The phase with the highest phase voltage and the phase with the lowest phase voltage are turned on, and regenerative power is regenerated to the phase with the highest line voltage. This is to reduce the regenerative current.

However, in the configuration in which the photocoupler 2 is directly connected to the AC power source as described above, it is not possible to arbitrarily adjust the timing at which the photocoupler is turned on and off.

For example, in FIG. 3, section 1. The photocoupler P1 turns off at the If boundary, but it is physically impossible to turn off earlier after the off signal is received.

As a result, the peak value IP of the phase current (determined by the timing at which the electric valve is turned off) cannot be suppressed, and the rated capacity of the electric valves B1 to B6, which is determined by the peak value IP of the phase current, must be large. It has the disadvantages of being expensive and large.

[Summary of the invention]

This invention was made for the purpose of improving this drawback. By inserting a resistor into each phase silver in the connection path between the AC power supply and the photocoupler, the timing of turning on and off the photocoupler is changed, and the timing of turning on and off the photocoupler is changed. This paper proposes a power regeneration device that can reduce the peak value of current.

[Embodiments of the invention]

FIG. 4 is a circuit diagram showing one embodiment of the present invention.
9 is exactly the same as the conventional circuit shown in FIG. "
are resistors inserted in the connection paths between each phase U, V, and W of the AC power source 4 and the photocouplers P1 to P6 that constitute the phase voltage detection circuit 9.

In the power regeneration device configured as described above, the power supply from the rectifier circuit 1 to the smoothing capacitor 5 and the power regeneration operation from the smoothing capacitor 5 to the AC power source 4 are the same as in the conventional circuit. The peak value of the phase current during regeneration can be reduced by making the timing of turning off earlier.

This will be explained in further detail with reference to Figure 5. FIG. 5 shows section 1 of the three-phase waveform shown in FIG. 3(a). This is a simplified circuit of a part of the phase voltage detection circuit corresponding to ff. Section I when there is no resistance r.

At the boundary B, photocoupler P2 is turned on, Pl is turned from on to off, and Pl is turned from off to on. On the other hand, when there is a resistor r in the connection path of the AC source 4 of each of the photocouplers PI to P5, when the photocouplers p+ and P2 are on, the voltage v1 is smaller than when there is no resistor r. Therefore, the photocoupler P5 turns on earlier than when there is no resistor r.

Also, the reason why photocoupler P1 turns off is that in this case, photocoupler P1 is on, so the voltage V
1 is small. Therefore, the turning off of photocoupler P1 is delayed.

Therefore, by inserting the resistor r, the photocoupler operates as shown in FIG. At point t'1 in FIG. 6, photocoupler P1 is turned on, and at point t1, photocoupler P3 is turned off.

As a result, the timing at which the photocoupler is turned on and off can be changed as shown in FIG.

For example, a plurality of AND gates 01 to G configured as shown in FIG.
6, photocoupler PS,! : P5 and P
4 and P6 signals from the electric valve drive circuit 9 to the electric valve B.
+, B2 drive signal m1. By outputting m2, the timing at which the electric valve is turned off becomes as early as Δ, and the peak value of the phase current can be reduced.

〔Effect of the invention〕

As described above, the present invention can shift the detection timing of the phase voltage, so that the peak value of the phase current during regeneration can be reduced. As a result, it is possible to use a small, inexpensive electric valve with a small rated capacity for flowing phase current during regeneration.

Although the illustrated example shows a three-phase AC power source as the AC power source, it may be a single phase or a polyphase AC power source having three or more phases.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a conventional power regeneration device, Fig. 2 is a circuit diagram showing an example of a conventional signal generation circuit, Fig. 3 is a waveform diagram, and Fig. 4 is a circuit showing an embodiment of the present invention. 5 is a simplified circuit diagram of a part of the phase voltage detection circuit, FIG. 6 is an explanatory diagram of the operation of the photocoupler, FIG. 7 is a waveform diagram, and FIG. 8 is an example of the signal generation circuit of the present invention. It is a circuit diagram. DESCRIPTION OF SYMBOLS 1... Rectifier circuit, 2... Regeneration circuit, 3... AC reactor, 4... AC power supply, 5... Smoothing capacitor, 6... Inverter circuit, 7... AC load, 8・・・
・Phase voltage detection circuit, 9... Electric valve drive circuit, r...
It is resistance. In each figure, the same reference numerals indicate the same or corresponding parts. Patent applicant: Mitsubishi Electric Corporation l+;, T7. -7'77 I Agent Patent Attorney 1) Hiroshi Sawa 1991. 24)"・' Figure 3 Figure 8 r----'---------------'------1 Procedural amendment (voluntary) 1. Indication of πr'+ Special Application No. 59-43885 2゜Name of the invention Power regeneration device (U.Relationship with the person making the amendment A1 Patent applicant S1Mi Place Chiyoda-ku, Tokyo) L-no-uchi 2-1'' 2-3 Name (601) Mitsubishi Electric Co., Ltd. Representative Jinhachibe Katayama 4, Agent Postal code 105 Address 1-4-10-5, Nishishinka 1-chome, Minato-ku, Tokyo Subject of amendment (1) Regarding the invention in the description Detailed explanation column (2) Drawing 6, Contents of amendment (1) Delete "Power outage," in the second line of page 2 of the specification. (2) "Connect" in the third line of page 3 of the specification should be changed to "Connect and connect each photocoupler to diodes DI3 to DI8."
Correct by connecting via ``. (3) Delete "Power outage," on page 3, line 16 of the specification. (4) Amend Figure 1 as shown in the attached sheet. (5) Amend Figure 4 as shown in the attached sheet. 7. List of attached documents

Claims (1)

[Claims] A plurality of diode groups that rectify the AC output of the AC power source and charge a smoothing capacitor as a DC power source, and when the charging voltage of the smoothing capacitor becomes higher than the AC power source voltage, power is regenerated from the smoothing capacitor to the AC power source. A rectification/regeneration circuit composed of a plurality of electric valve groups capable of forced commutation, a phase voltage detection circuit composed of a plurality of photocouplers for detecting the phase voltage of the AC power supply, and a detection signal of the phase voltage detection circuit; and an electric valve drive circuit that sequentially supplies a drive signal to the electric valve, characterized in that a resistor is inserted in a connection path to the alternating current power source of a photocoupler constituting the phase voltage detection circuit. Power regeneration device.