JP2012222998A - Voltage control circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a voltage control circuit which can convert an input voltage having a large range of changes to an output voltage having any definite magnitude in an easily controllable way.SOLUTION: The voltage control circuit includes a transformer primary side TP and a transformer secondary side TS. The transformer primary side TP includes a plurality of transformer primary windings TL11 and TL21, a plurality of resonance circuits RS1 and RS2, a plurality of switching element circuits SW1 and SW2, and a plurality of drive circuits DV1 and DV2. The transformer secondary side TS includes a plurality of transformer secondary windings TL21 and TL22, a rectification circuit DC including a plurality of diodes D1 to D4, and a synthesis circuit SUM which synthesizes outputs of the rectification circuit DC. The drive circuits DV1 and DV2 of the transformer primary side TP maintains the frequency of an input voltage Vi from a solar battery PV1 at the same level as f0 and also changes the phase thereof, whereby it is made possible to variably control the magnitude of an output voltage VO synthesized by the synthesis circuit SUM on the transformer secondary side.

Description

  The present invention relates to a voltage control circuit capable of controlling a constant output voltage over a wide input voltage range.

  A solar power generation system is composed of a solar cell and a power conditioner. The solar cell converts solar energy into electricity, and the power conditioner has a power conversion function corresponding to the supply conditions to the load and power system. Have. In such a solar power generation system, the power conditioner includes a DC / DC converter that DC / DC converts the input voltage of the solar cell into another output voltage.

  On the other hand, a solar cell has a wide input voltage change range due to, for example, sunlight or a load. Therefore, in a DC / DC converter, a wide range of input voltage from the solar cell is stably DC / DC converted into a constant output voltage. We need to be able to do it.

  Of course, such DC / DC conversion is not limited to solar cells, but has the same problem with other distributed power sources such as power sources in wind power generation systems and other power sources. Therefore, there is a need for a DC / DC converter that can easily perform control for DC / DC conversion of the output voltage at a constant level and can transmit power efficiently at that time.

JP 2009-038969 A JP 2006-149170 A

  Therefore, in the present invention, it is an object to be solved to provide a voltage control circuit that can easily control conversion to a DC output voltage of an arbitrary magnitude in response to a DC input voltage having a large change range. .

The voltage control circuit according to the present invention includes a transformer primary side and a transformer secondary side,
The transformer primary side includes a plurality of transformer primary windings, a plurality of resonance circuits that are individually connected to each transformer primary winding and resonate at a predetermined frequency, and a DC power supply input voltage is switched at a predetermined frequency to switch each primary winding. A plurality of switching element circuits that are individually applied to the lines, and a plurality of driving circuits that individually drive each of the switching element circuits,
The transformer secondary side includes a plurality of secondary windings connected in series with each other, a rectifier circuit including a plurality of diodes for rectifying each secondary winding output, and a combining circuit for combining the rectifier circuit outputs, Including
Each of the drive circuits on the primary side of the transformer maintains the same frequency as the input voltage from the DC power supply, and the magnitude of the output voltage synthesized by the synthesis circuit on the secondary side of the transformer by changing its phase. It is characterized by enabling control to vary the height.

  In the present invention, for the voltage control circuit, by controlling the phase of the input voltage on each of the transformer primary side with respect to the DC power supply so as to input a DC input voltage having a large change range such as a solar cell, The magnitude of the output voltage can be easily adjusted arbitrarily.

  Preferably, each of the plurality of switching element circuits on the primary side of the transformer includes a plurality of switching elements that are half-bridge connected, and each of the plurality of driving circuits is each switching element in the corresponding half-bridge circuit. Are alternately turned on and off at a constant frequency and 180 degrees opposite phase.

  Preferably, the voltage control circuit is a switching power supply.

  Preferably, the voltage control circuit is a DC / DC converter.

  In the present invention, even if the input voltage from the DC power supply changes greatly, the magnitude of the output voltage can be controlled to an arbitrary constant level.

FIG. 1 is a circuit diagram of a voltage control circuit according to an embodiment of the present invention. FIG. 2 is a diagram showing a driving voltage waveform of the driving circuit on the primary side of the transformer in the circuit of FIG. FIG. 3 is a diagram showing the phase state of the output voltage of each secondary winding on the transformer secondary side in the circuit of FIG. FIG. 4 is a diagram showing the magnitude of the output voltage synthesized by the synthesis circuit on the transformer secondary side in the circuit of FIG. 1 as a vector.

  Hereinafter, a voltage control circuit according to an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows a configuration of a voltage control circuit according to an embodiment of the present invention. In the embodiment, the voltage control circuit is applied to the DC / DC converter in the power conditioner of the photovoltaic power generation system, but is not particularly limited to this, and may simply be a switching power supply or the like. And the voltage made into the control object in the voltage control circuit of this embodiment is the input voltage from the solar cell which is direct current power supply, and the voltage control circuit of embodiment is DC in the power conditioner in the solar power generation system. As an / DC converter, an example in which an input voltage from a solar cell is DC / DC converted into a constant output voltage is shown.

  Referring to FIG. 1, the DC / DC converter of the embodiment includes a transformer primary side TP and a transformer secondary side TS. These are the primary side and the secondary side of the two transformers T1 and T2, respectively. The transformer primary TP includes primary windings TL11 and TL21 of the transformers T1 and T2, and a plurality of resonance circuits RS1 and RS2 that resonate at a predetermined frequency f0 that are individually connected to the primary windings TL11 and TL21. A plurality of switching element circuits SW1 and SW2 that perform switching operation at a predetermined frequency f0 and individually apply the input voltage Vi of the DC power source PV1 to the primary windings TL11 and TL21, and the switching element circuits SW1 and SW2 are set to the predetermined frequency f0. And a plurality of drive circuits DV1 and DV2 that are individually switched and driven. Switching element circuits SW1 and SW2 include transistors Q1-Q4 such as IGBTs and MOSFETs connected in series in a half-bridge configuration. Drive circuits DV1 and DV2 include oscillation circuits V1 and V2 that oscillate in pulses and inversion circuits INV1 and INV2.

  The transformer secondary TS is a rectifier that individually rectifies a plurality of secondary windings TL21 and TL22 of two transformers T1 and T2 connected in series with each other and outputs VS1 and VS2 of the secondary windings TL21 and TL22. A circuit DC and a synthesis circuit SUM that synthesizes the output of the rectifier circuit DC and outputs it as an output voltage Vo are included.

  The rectifier circuit DC includes a diode D1 having an anode connected to one end of the secondary winding TL12 of the transformer T1, a diode D2 having an anode connected to the other end of the secondary winding TL22 of the transformer T2, and a transformer T1. A diode D3 having a cathode connected to one end of the secondary winding TL12, and a diode D4 having a cathode connected to the other end of the secondary winding TL22 of the transformer T2. Diodes D1 and D2 have a cathode connected in common, and diodes D3 and D4 have an anode connected in common. The synthesis circuit SUM includes a resistor R connected in parallel to a common cathode connection a between the diodes D1 and D2 and an common anode connection b between the diodes D3 and D4.

  In the DC / DC converter having the above configuration, the drive circuit V1 on the transformer primary side TP outputs a pulse output S1 having a waveform shown in FIG. The drive circuit V2 on the primary side TP of the transformer outputs a pulse output S2 having the same phase as the pulse output S1 in FIG. 2B1, and a pulse output S2 having a phase delay of 90 degrees with respect to the pulse output S1 in FIG. In FIG. 2B3, a pulse output S2 having a phase delay of 180 degrees with respect to the pulse output S1 is output. The frequency of these pulse outputs S1 and S2 is the same at f0.

  In the transformer primary side TP drive circuit V1, the switching element circuit SW1 is switched and driven by the pulse output S1 having the frequency f0 shown in FIG. In this case, the pulse output S1 is directly applied to the switching element Q1, and the pulse output S1 is applied to the switching element Q2 with the phase inverted by the inversion circuit INV1, thereby turning on and off the switching elements Q1 and Q2 alternately. . As a result, the output of the switching element circuit SW1 corresponding to the frequency f0 is input to the resonance circuit RS1, and the resonance circuit RS1 resonates with this output. As a result, a sinusoidal AC output VS1 shown in FIG. 3A is induced between the primary winding TL11 of the transformer T1 and both ends of the secondary winding TL12.

  Further, the driving circuit V2 on the transformer primary side TP performs switching driving of the switching element circuit SW2 with the pulse output S2 having the frequency f0 shown in FIG. In this case, the pulse output S2 is directly applied to the switching element Q3, and the pulse output S2 is applied to the switching element Q4 with its phase inverted by the inversion circuit INV2, whereby the switching elements Q3 and Q4 are alternately turned on and off. . As a result, the output of the switching element circuit SW2 corresponding to the frequency f0 is input to the resonance circuit RS2, and the resonance circuit RS2 resonates with this output. As a result, a sinusoidal AC output VS2 shown in FIG. 3B1 is induced between the primary winding TL21 of the transformer T2 and both ends of the secondary winding TL22.

  Since the pulse output S1 of FIG. 2 (a) and the pulse output S2 of FIG. 2 (b1) are in phase, the AC output of the sine waveform shown in FIG. 3 (a) between both ends of the secondary winding TL12 of the transformer T1. The VS1 and the AC output VS2 having a sinusoidal waveform shown in FIG. 3B1 between both ends of the secondary winding TL22 of the transformer T2 are in phase.

  Similarly, since the pulse output S1 in FIG. 2A and the pulse output S2 in FIG. 2B2 are 90 degrees out of phase, FIG. 3 (between both ends of the secondary winding TL12 of the transformer T1). The sine waveform AC output VS1 shown in a) and the sine waveform AC output VS2 shown in FIG. 3B2 between both ends of the secondary winding TL22 of the transformer T2 are 90 degrees out of phase.

  Similarly, since the pulse output S1 of FIG. 2A and the pulse output S2 of FIG. 2B3 are 180 degrees out of phase, FIG. 3A is shown between both ends of the secondary winding TL12 of the transformer T1. ) And the sinusoidal AC output VS2 shown in FIG. 3 (b3) between both ends of the secondary winding TL22 of the transformer T2 are 180 degrees out of phase.

  The rectifier circuit DC of the transformer secondary TS rectifies the voltages VS1 and VS2 across the secondary windings TL12 and TL22 of the transformers T1 and T2, respectively, and the synthesizer circuit SUM synthesizes the rectifier circuit DC output. However, when the voltages VS1, VS2 across the secondary windings TL12, TL22 are in the relationship of FIG. 3A and FIG. 3B1, the resistance in the composite circuit SUM is shown in FIG. 4A. The voltage between both ends of R, that is, the output voltage VO of the DC / DC converter, is a combined vector of the voltages VS1 and VS2 between both ends and takes the maximum value. Further, when the voltages VS1, VS2 across the secondary windings TL12, TL22 are in the relationship of FIG. 3 (a) and FIG. 3 (b2), the output voltage VO is shown in FIG. 4 (b). It becomes a composite vector of the voltages VS1 and VS2 between both ends, and VO = √2VS. However, VS1 = VS2 = VS. Further, when the voltages VS1, VS2 across the secondary windings TL12, TL22 are in the relationship of FIG. 3 (a) and FIG. 3 (b3), the output voltage Vo is shown in FIG. 4 (c). It becomes a combined vector of the voltages VS1 and VS2 between both ends, and Vo = 0.

  From the above, the frequency of the pulse outputs S1 and S2 of the drive circuits DV1 and DV2 on the transformer primary side TP is set to f0, and the phase of the pulse output S2 is controlled with respect to the pulse output S1, thereby the output voltage Vo of the DC / DC converter. Can be controlled to an arbitrary value.

  In the above embodiment, there are two transformers. However, a larger number of transformers may be used.

  In the above embodiment, the power source PV1 is a solar cell, but is not limited to this, and includes a power source in wind power generation, a battery power source such as an electric vehicle, and others.

  As described above, in this embodiment, the transformer primary side TP and the transformer secondary side TS are included, and the transformer primary side TP includes a plurality of transformer primary windings TL11 and TL21 and the transformer primary windings TL11 and TL21. And a plurality of switching circuits that individually connect to the primary windings TL11 and TL21 by switching the input voltage Vi of the DC power source PV1 at the predetermined frequency f0. Including element circuits SW1 and SW2 and a plurality of drive circuits DV1 and DV2 that individually switch drive each of the switching element circuits SW1 and SW2 at a predetermined frequency f0. A plurality of transformer secondary TS are connected in series with each other. Secondary windings TL21 and TL22 and a plurality of diodes D1-D4 for rectifying the respective secondary winding outputs. The rectifier circuit DC and the synthesis circuit SUM that synthesizes the output of the rectifier circuit DC. The drive circuits DV1 and DV2 of the transformer primary side TP have the same frequency f0 as the input voltage Vi from the solar cell PV1. And by changing the phase thereof, it is possible to control to vary the magnitude of the output voltage Vo synthesized by the synthesis circuit SUM of the transformer secondary TS, so that the drive circuit DV1 is provided on each transformer primary TP. By controlling the phase of the pulse outputs S1 and S2 of DV2, the output voltage Vo can be easily increased by 0-2 times with respect to a power source having a large change range of the input voltage Vi as in the solar cell PV1. Can be adjusted to constant within. Further, since the transformers T1 and T2 are driven at a constant frequency f0, it is possible to increase the Q value of the resonance circuits RS1 and RS2 in the transformer primary side TP and transmit power with high efficiency.

TP transformer primary side DV1, DV2 drive circuit SW1, SW2 switching element circuit RS1, RS2 resonance circuit TS transformer secondary side DC rectifier circuit SUM synthesis circuit

Claims (2)

Including a transformer primary side and a transformer secondary side,
The transformer primary side includes a plurality of transformer primary windings, a plurality of resonance circuits that are individually connected to each transformer primary winding and resonate at a predetermined frequency, and a DC power supply input voltage is switched at a predetermined frequency to switch each primary winding. A plurality of switching element circuits that are individually applied to the lines, and a plurality of driving circuits that individually drive each of the switching element circuits,
The transformer secondary side includes a plurality of secondary windings connected in series with each other, a rectifier circuit including a plurality of diodes for rectifying each secondary winding output, and a combining circuit for combining the rectifier circuit outputs, Including
Each of the drive circuits on the primary side of the transformer maintains the same frequency as the input voltage from the DC power supply, and the magnitude of the output voltage synthesized by the synthesis circuit on the secondary side of the transformer by changing its phase. Made it possible to change the control.
A voltage control circuit.   The plurality of switching element circuits on the primary side of the transformer each include a plurality of switching elements that are half-bridge connected, and the plurality of driving circuits each have a constant switching element in the corresponding half-bridge circuit. The voltage control circuit according to claim 1, wherein the voltage control circuit is alternately turned on and off at the same frequency and with an opposite phase of 180 degrees.

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