JP6301150B2 - Power converter - Google Patents

Description

  The present invention relates to a power converter that includes a circuit in which a DC power source and an AC power source are connected in series via an inverter and is connected in parallel to the inverter and supplies a DC voltage.

  2. Description of the Related Art Conventionally, there is known a power conversion device in which a DC power source such as a solar cell or a fuel cell and an AC power source such as a commercial power source are connected in series via an inverter that converts DC power into AC power. (For example, Patent Document 1).

  This power converter is also known to have a circuit including a diode bridge that is provided in parallel with an inverter and converts an AC voltage input from an AC power supply in an AC line into a DC voltage. In this case, the AC line and the DC line are connected via a diode bridge, and the DC voltage is supplied to the switching regulator provided in the DC line at night or the like, converted into a predetermined voltage, and then supplied to the load. Is done.

Japanese Patent Laid-Open No. 7-147781

  By the way, in general, when the inverter is driven by unipolar switching or the like, a high-frequency square wave voltage may be superimposed as noise on the output or input side with respect to the ground phase potential. In the above power converter, when a DC voltage supply circuit including a diode bridge is connected to the inverter, a high-frequency spike-like leakage current flows from the AC line side and may circulate inside and outside the device.

  Doing so will cause problems that adversely affect EMC (Electromagnetic Compatibility), such as electromagnetic noise on communication devices and electromagnetic effects on other devices, and damage to diodes due to an increase in input voltage to the diode bridge. Such problems may occur.

  On the other hand, in order to prevent the circulation of high-frequency leakage current, it is also assumed that the switching regulator is an insulation type, but in that case, it is necessary to provide an insulation type switching regulator in both or one of the AC line and the DC line. In some cases, the number of the insulating switching regulators is two, and the size of the apparatus increases, and it is necessary to provide a filter for noise from the insulating switching regulator, which makes the configuration complicated.

  The present invention solves the above-mentioned problems, and when a DC power source and an AC power source are connected in series via an inverter and has a circuit connected in parallel with the inverter to supply a DC voltage, An object of the present invention is to provide a power converter that can reliably and easily prevent the resulting high-frequency current from circulating inside and outside the device.

  In order to achieve the above object, a power converter according to one configuration of the present invention includes a DC power source and an AC power source connected in series via an inverter, and connected in parallel with the inverter to supply a DC voltage. A voltage supply circuit; The DC voltage supply circuit includes a diode bridge that converts an AC voltage input from an AC power supply in an AC line into a DC voltage, and a switching regulator that converts a DC voltage input from the DC power supply in the DC line into a predetermined voltage. Further, a relay unit that is arranged between an AC power source and a diode bridge in an AC line, relays off the AC power source and the diode bridge when the inverter is operating, and relays on the AC power source and the diode bridge when the inverter is stopped. It has.

  According to this configuration, since the relay unit relays off the AC power supply and the diode bridge during the inverter operation, it is possible to prevent the high-frequency (spike) current generated from the inverter from circulating inside and outside the apparatus, and to stop the inverter Sometimes, no high-frequency current is generated from the inverter, so that even if the AC power supply and the diode bridge are relayed on, they do not circulate. Thereby, it is possible to reliably and easily prevent the high-frequency current from circulating inside and outside the apparatus, and supply the DC voltage to the switching regulator.

  In the present invention, it is preferable that a booster circuit for boosting a DC voltage is provided between the DC power source and the inverter. In this case, the DC voltage can be boosted to a desired voltage and input to the inverter.

  The present invention prevents the high frequency (spike) current from circulating inside and outside the apparatus by relaying off the AC power supply and the diode bridge when the inverter is operating, and no high frequency current is generated from the inverter when the inverter is stopped. Even if the AC power supply and the diode bridge are relayed on, they do not circulate, so that it is possible to reliably and easily prevent the high-frequency current from circulating inside and outside the apparatus and supply the DC voltage to the switching regulator.

It is a circuit block diagram which shows the power converter device which concerns on one Embodiment of this invention. It is a characteristic view which shows the result of the simulation by a simulator.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a circuit configuration diagram showing a power converter according to an embodiment of the present invention. As shown in FIG. 1, the power converter 1 includes a DC power source 2 such as a solar cell or a fuel cell and an AC power source 3 such as a commercial power source connected in series via an inverter 5. A DC voltage supply circuit 6 is connected to supply a DC voltage to the switching regulator 8. Between the DC power supply 2 and the inverter 5, a booster circuit 4 that boosts the DC voltage is provided.

  The inverter 5 converts DC power into AC power, and is composed of a bridge of a unipolar switching element such as a MOS-FET. Unipolar type switching elements have better conversion efficiency than bipolar types. The surplus power of the DC power source 2 is grid-connected to the AC power source 3 under the control of a control unit (not shown).

  The DC voltage supply circuit 6 converts a DC voltage input from the AC power supply 3 in the AC line 13 into a DC voltage and a DC voltage input from the DC power supply 2 in the DC line 12 into a predetermined voltage. And a switching regulator 8 for supplying to the load 9.

  Here, the DC line 12 is a wiring from the DC power supply 2 to the inverter 5 and from the connection point 14 on the DC power supply 2 side in the DC voltage supply circuit 6 to the diode bridge 7. The AC line 13 is a wiring from the AC power source 3 to the inverter 5 and from the connection point 15 on the AC power source 3 side in the DC voltage supply circuit 6 to the diode bridge 7. That is, in the DC voltage supply circuit 6 that is connected in parallel to the inverter 5 and supplies a DC voltage to the load 9, the DC line 12 and the AC line 13 are connected via the diode bridge 7.

  The load 9 is mainly a household load, and the switching regulator 8 is a DC low voltage power supply device having a low voltage of 5V to 24V, and is used as a power supply for a minicomputer or a remote controller.

  In the DC voltage supply circuit 6, when the DC power source 2 is a solar cell, the DC voltage is supplied to the load 9 via the switching regulator 8 during the daytime and cannot be supplied at night. Is supplied with a DC voltage via the diode bridge 7. When the DC power source 2 is a fuel cell, the DC voltage can be supplied regardless of day or night, and the DC voltage can be supplied even when the AC power source 3 is in a power failure. These operations are automatically controlled by a control unit (not shown).

  The power conversion device 1 is further disposed between the AC power source 3 and the diode bridge 7 to relay off between the AC power source 3 and the diode bridge 7 when the inverter is operating, and when the inverter is stopped, the AC power source 3 and the diode bridge. 7 is provided with a relay section 10 that relays on between the two.

  That is, the relay unit 10 disconnects between the AC power source 3 and the diode bridge 7 by relaying off during the inverter operation, and supplies a DC voltage to the switching regulator 8 from the DC power source 2 side. When the relay is turned on when the inverter is stopped, the DC voltage converted by the diode bridge 7 is supplied from the AC power source 3 side to the switching regulator 8. Therefore, the DC voltage can be constantly supplied from the DC power source 2 or the AC power source 3 to the switching regulator 8.

  Since the relay unit 10 disconnects between the AC power supply 3 and the diode bridge 7 during the inverter operation, it is possible to prevent the high-frequency leakage (spike) current generated from the inverter 5 from circulating. Since no high frequency current is originally generated from the inverter 5, it does not circulate even if the AC power supply 3 and the diode bridge 7 are relayed on. Thereby, it is possible to prevent the high-frequency current from circulating inside and outside the apparatus, and to supply the DC voltage to the switching regulator 8.

  FIG. 2 is a characteristic diagram showing the result of simulation by the simulator. In this figure, the relay unit 10 is in a relay-on state, and a high-frequency spike-like leakage current is generated. The upper side of the figure is a negative leakage current, and the lower side is a positive leakage current. As a result of simulation, it was confirmed that this high-frequency leakage current does not occur when the relay unit 10 is turned off.

  This eliminates problems that adversely affect EMC (electromagnetic compatibility) such as electromagnetic noise on communication devices and electromagnetic effects on other devices, and suppresses an increase in input voltage to the diode bridge 7. Problems such as damage to the diode are eliminated.

  Thus, according to the present invention, since the relay unit relays off the AC power supply and the diode bridge during the inverter operation, the high frequency (spike) current generated from the inverter can be prevented from circulating inside and outside the apparatus, and the inverter is stopped. Sometimes, no high-frequency current is generated from the inverter, so that even if the AC power supply and the diode bridge are relayed on, they do not circulate. Thereby, it is possible to reliably and easily prevent the high-frequency current from circulating inside and outside the apparatus, and supply the DC voltage to the switching regulator.

  In this embodiment, the connection point 14 on the DC power supply 2 side of the DC voltage supply circuit 6 is provided between the booster circuit 4 and the inverter 5, but is provided between the DC power supply 2 and the booster circuit 4. Also good. Further, the booster circuit 4 may be omitted if necessary.

  In this embodiment, one DC power source 2 is used, but a plurality of DC power sources 2 may be provided in parallel.

1: Power converter 2: DC power supply 3: AC power supply 4: Booster circuit 5: Inverter 6: DC voltage supply circuit 7: Diode bridge 8: Switching regulator 9: Load 10: Relay unit

Claims (2)

A power converter having a DC voltage supply circuit in which a DC power source and an AC power source are connected in series via an inverter that is driven by unipolar switching, and connected in parallel with the inverter to supply a DC voltage,
The DC voltage supply circuit includes:
A diode bridge that converts an AC voltage input from an AC power supply in the AC line to a DC voltage; and a switching regulator that converts a DC voltage input from the DC power supply in the DC line to a predetermined voltage;
Further, the AC power source and the diode bridge are disposed during the operation of the inverter so as to be constantly disposed between the AC power source and the diode bridge in the AC line so that high-frequency current caused by the inverter circulates inside and outside the apparatus. And a relay section that relays on the AC power source and the diode bridge when the inverter is stopped. In claim 1,
A power converter, wherein a booster circuit that boosts a DC voltage is provided between the DC power supply and the inverter.

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