JPH0965657A - Power converter for solar power generation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power converter for solar power generation which does not require any commercial transformer for output nor any other solar battery than one, and can use such a solar battery that outputs a voltage lower than the voltage required by a half-bridge inverter. SOLUTION: The output voltage of a solar battery 1 is boosted to the voltage required to be inputted to an inverter by means of a boosting chopper constituted of a reactor 5, an IGBT 6, and a diode 7 after the voltage is smoothed by means of a capacitor 8. The boosted voltage is equally divided to capacitors 3 and 4 and the mid-potential point of the divided voltages is connected to a single-phase three-wire neutral point. The energy stored in the capacitors 3 and 4 is converted into single-phase three-wire power by means of IGBTs 9, 10, 11, and 12 constituting a half-bridge inverter and supplied to a system power source 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter for photovoltaic power generation which converts DC output power of a solar cell into AC power of a single-phase three-wire system power source and outputs the AC power.

[0002]

2. Description of the Related Art Conventionally, the DC output power of a solar cell is single phase 3
Japanese Patent Application Laid-Open No. 5-111165 (FIG. 2) and Japanese Patent Application Laid-Open No. 4-1 are known as devices for converting and outputting AC power of a wire system power source.
There was one disclosed in No. 65963 (FIG. 3). FIG.
In the device shown in Fig. 1, a large commercial transformer 13 is connected to the output of a single-phase full bridge inverter composed of IGBTs 9, 10, 11, and 12, and the output power of the solar cell 1 is smoothed by a capacitor 8 to obtain a DC voltage. Is converted into alternating current by a full bridge inverter, and the commercial transformer 13 converts the single-phase two-wire type output into the single-phase three-wire type output and supplies it to the system power supply 14. On the other hand, the device shown in FIG. 3 has two solar cells 1 and 2, two capacitors 3 and 4 and an IBGT 9 and 1.
AC power is obtained by using two half bridge inverters 0, 11, and 12 and supplied to the system power supply 14.

[0003]

The output voltage of the solar cell fluctuates greatly depending on the temperature. In addition, depending on the type of solar cell, the output voltage is relatively low. However, with the former conventional technology that uses a transformer and an inverter, it is difficult to provide a wide range of input voltage corresponding to these solar cells, and it is necessary to prepare a dedicated inverter and transformer for a specific solar cell. Since the output transformer was large and heavy, the inverter body was also large and heavy. Further, in the latter conventional technique using two half-bridge inverters, two solar cells are required, and a control circuit or the like for independently controlling each solar cell is required, so that the number of circuit components becomes large and complicated. was there.

It is an object of the present invention to use a solar cell which does not require a commercial transistor for its output, one solar cell is sufficient, and an output voltage which is lower than the voltage required by a half-bridge inverter can be used. It is to provide a conversion device.

[0005]

In order to achieve the above object, a power conversion device for photovoltaic power generation according to the present invention includes a booster circuit for boosting the output voltage of a solar cell and an output voltage boosted by the booster circuit. It has two capacitors for voltage division and two half-bridge inverters for converting into power of a single-phase three-wire system power supply, and the mid-potential point of the voltage divided by the capacitor is for the single-phase three-wire system. It is connected to the neutral point of the power supply. In the power converter for photovoltaic power generation of claim 2, the booster circuit is a booster chopper.

[0006]

Since the booster circuit boosts the output voltage of the solar cell, the input voltage of the half-bridge inverter can be sufficiently secured, so that one solar cell, which was necessary for two, is sufficient.
Therefore, only one control circuit to control the solar cell is required,
The number of parts can be reduced and the device can be downsized. Further, a solar cell with a low output voltage can be used, and the input voltage of the half-bridge inverter can be stabilized.

[0007]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a circuit diagram of a photovoltaic power converter according to an embodiment of the present invention. Reactor 5, IGBT
6, the diode 7 constitutes a step-up chopper, and the capacitors 3, 4 and the IGBTs 9, 10, 11, 12 constitute a single-phase three-wire inverter (two half-bridge inverters). The voltage output from the solar cell 1 is the capacitor 8
After being smoothed by, the voltage is first boosted by the boost chopper to the voltage required for the input of the inverter. Due to this boosting operation, the inverter can operate even if the output voltage of the solar cell 1 is low, and even if the rated output voltage of the solar cell 1 is relatively low, it can be used. The boosted voltage is equally divided by capacitors 3 and 4 of the same capacity connected in series, and the medium potential point of the divided voltage is connected to the single-phase three-wire neutral line. The energy stored in the capacitors 3 and 4 is converted into electric power of a single-phase three-wire system by two half-bridge converters, and is supplied to the system power supply 14.

[0008]

As described above, the present invention has the following effects. (1) Since a commercial transformer is not required for output, the weight of the device can be reduced. (2) Since only one solar cell is required, the device can be downsized. (3) A solar cell whose output voltage is lower than the voltage required for the half-bridge inverter can be used. (4) The input voltage of the half bridge inverter can be stabilized.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a power conversion device for photovoltaic power generation according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a conventional example.

FIG. 3 is a circuit diagram of another conventional example.

[Explanation of symbols]

 1,2 Solar cell 3,4,8 Capacitor 5 Reactor 6,9,10,11,12 IGBT 7 Diode 13 Commercial transformer 14 System power supply

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsuneo Kume No.2-1 Kurosaki Shiroishi, Yawatanishi-ku, Kitakyushu, Fukuoka Prefecture Yasukawa Electric Co., Ltd.

Claims (2)

[Claims] 1. A power conversion device for photovoltaic power generation for converting DC output power of a solar cell into AC power, and a booster circuit for boosting the output voltage of the solar cell, and the output voltage boosted by the booster circuit is divided. Two capacitors and single phase 3
It has two half-bridge inverters for converting the electric power of a line type system power supply, and the middle potential point of the voltage divided by the capacitor is connected to the neutral point of the single-phase three-wire type system power supply. A characteristic power conversion device for photovoltaic power generation. 2. The power conversion device for photovoltaic power generation according to claim 1, wherein the booster circuit is a booster chopper.