JP4985795B2 - Solar power generation apparatus and solar power generation system - Google Patents

Description

  The present invention relates to a solar power generation apparatus and a solar power generation system in which solar cells are connected in series.

The solar power generation device converts solar energy into electric energy, and has attracted attention as clean energy that does not generate CO2.
Since the generated voltage per unit cell (solar cell element) of the solar battery is as low as 1 V or less, blocks in which a plurality of solar cell elements are connected in series are connected in series and parallel.

  When a part of the solar cell elements connected in series is hidden in the shadow, the solar cell element cannot only generate power but also has high resistance. In this case, the recovery efficiency of all the power generation energy of the solar cell elements connected in series is lowered.

  For this reason, a diode is connected in parallel to the solar cell element (single cell) or several cells, and the generated energy is diverted from the high-resistance solar cell element, thereby improving the recovery efficiency of the entire generated energy.

  FIG. 4 is a circuit configuration diagram showing an example of a conventional solar power generation device (Patent Document 1). The solar power generation device shown in FIG. 4 comprises a solar cell block 3 by a series circuit in which three solar cell elements 1 are connected in series and a diode 2 (a bypass diode) connected in parallel at both ends of the series circuit. is doing.

  The solar power generation device 4 configured by connecting the solar cell blocks 3 in series supplies power to the load 5. The load 5 is configured by a storage battery or a grid-linked inverter, and regenerates the generated energy and regenerates the AC system.

  Moreover, as shown in FIG. 5, the solar power generation device shown in FIG. 4 is connected by connecting the solar power generation devices 4-1 to 4-n in parallel to the load 5 via the diodes 6-1 to 6-n. Even higher output can be obtained.

JP 56-69871 A

  However, in the photovoltaic power generation apparatus shown in FIG. 4 in which the diode 2 is connected in parallel to the series circuit of the three solar cell elements 1, heat generation due to the voltage drop of the diode 2 is large, and this heat generation reduces the efficiency of the entire system. It was.

  Moreover, in the solar power generation device shown in FIG. 5 in which the solar power generation devices 4-1 to 4-n are connected in parallel, the generated voltage of each solar power generation device varies depending on the number of diodes 2 that are bypassed.

  In this case, the output power of the solar power generation device having the minimum power generation voltage is reduced by the solar power generation device that generates the maximum power generation voltage, and the power generation efficiency of the entire solar power generation system is reduced.

  An object of the present invention is to provide a photovoltaic power generation apparatus and a photovoltaic power generation system that can reduce loss due to a bypass diode and improve the power generation efficiency of the entire system.

In order to solve the above problem, the invention of claim 1 is characterized in that one or more solar cell elements connected in series and the one or more solar cell elements are connected in parallel and are irradiated with sunlight. the composite element composed of a semiconductor switch which is turned on when off and and the sunlight is irradiated, Ri Na connected to each other in series, wherein the semiconductor switch is made normally-on switch, the The second solar cell element is connected between the gate and the source of the semiconductor switch .

  According to the present invention, a semiconductor switch connected in parallel to one or more solar cell elements is turned off when sunlight is irradiated and turned on when sunlight is not irradiated. Since the on-voltage has a smaller voltage drop than the forward voltage Vf of the bypass diode, it is possible to reduce loss when bypassing one or more solar cell elements.

It is a circuit block diagram which shows the solar power generation device of Example 1. FIG. It is a figure which shows the characteristic of the semiconductor switch of the solar power generation device of Example 1, and the characteristic of the conventional diode. It is a circuit block diagram which shows the solar energy power generation system of Example 2. FIG. It is a circuit block diagram which shows an example of the conventional solar power generation device. It is a circuit block diagram which shows another example of the conventional solar power generation system.

  Hereinafter, embodiments of the photovoltaic power generation apparatus and the photovoltaic power generation system of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a circuit configuration diagram illustrating the photovoltaic power generation apparatus according to the first embodiment. 1 includes a series circuit in which three solar cell elements 1 are connected in series, a semiconductor switch 7 in which a drain-source is connected to both ends of the series circuit, and a semiconductor. A solar cell element 3a connected between the gate and source of the switch 7 constitutes a solar cell block 3a, and a plurality of solar cell blocks 3a are connected in series.

  The semiconductor switch 7 is a normally-on type switch made of a wide band gap semiconductor such as gallium nitride (GaN) or silicon carbide (SiC), and is turned off when irradiated with sunlight and irradiated with sunlight. Turn on when not.

  Note that a GaN high electron mobility transistor (HEMT) may be used instead of a wide band gap semiconductor such as GaN or SiC.

  Next, operation | movement of the solar power generation device of Example 1 comprised in this way is demonstrated. When the solar cell element 1 is not irradiated with sunlight, a voltage is generated in the solar cell element 1 and the gap between the gate and source of the semiconductor switch 7 is substantially zero, so the semiconductor switch 7 is turned on.

  On the other hand, when the solar cell element 1 is irradiated with sunlight, a cathode voltage is applied between the gate and source of the semiconductor switch 7, so that the semiconductor switch 7 is turned off. For this reason, the generated electric power of the solar cell element 1 is output.

  Thus, according to the solar power generation device of Example 1, the semiconductor switch 7 is turned off when sunlight is irradiated, and is turned on when sunlight is not irradiated, so as shown in FIG. Moreover, since the voltage drop of the on-voltage Von7 of the semiconductor switch 7 is smaller than the forward voltage Vf2 of the bypass diode 2, it is possible to reduce the loss when bypassing one or more solar cell elements 1.

  Further, in order to turn off the semiconductor switch 7, only the gate voltage is set to a negative potential, no gate drive loss occurs, and the efficiency during solar power generation is not reduced.

  That is, since the resistance of the bypass circuit by the semiconductor switch 7 is small as compared with the conventional solar power generation apparatus using the diode 2, even when the solar cell element 1 is hidden in the shade or the like, the entire solar power generation system Has little effect on

  FIG. 3 is a circuit configuration diagram illustrating the photovoltaic power generation system according to the second embodiment. The solar power generation system shown in FIG. 3 is configured by connecting solar power generation devices 4a-1 to 4a-4 in parallel to a load 5 via diodes 6-1 to 6-4. In addition, the parallel number of photovoltaic power generation devices is not limited to four.

  Each of the solar power generation devices 4a-1 to 4a-4 includes a series circuit in which three solar cell elements 1 are connected in series, a semiconductor switch 7 in which drain and source are connected to both ends of the series circuit, and a semiconductor. A solar cell block 3a-1 to 3a-4 is constituted by the solar cell element 1a connected between the gate and source of the switch 7, and a plurality of solar cell blocks 3a-1 to 3a-4 are connected in series. Configured.

  Current detection resistors 8-1 to 8-4 (detection units) are connected in series to each of the solar power generation devices 4a-1 to 4a-4. The current signals detected by the current detection resistors 8-1 to 8-4 are input to the control circuit 10.

In addition, you may detect the voltage of solar power generation device 4a-1-4a-4 instead of detecting the electric current which flows into solar power generation device 4a-1-4a-4.
In the second embodiment, the gates and sources of the semiconductor switches 7-1 to 7-4 in the solar cell blocks 3a-1 to 3a-4 closest to the control circuit 10 are connected to the control circuit 10.

  The control circuit 10 inputs and compares a plurality of currents from the plurality of current detection resistors 8-1 to 8-4, and based on the plurality of current values, removes the remaining current value among the plurality of current values. The semiconductor switch 7 is turned on by applying a control signal between the gate and the source of the semiconductor switch 7 in the photovoltaic power generation apparatus corresponding to the current value.

  Alternatively, the control circuit 10 inputs and compares the voltages of the solar power generation devices 4a-1 to 4a-4, and based on the plurality of voltage values, the remaining voltage excluding the smallest voltage value among the plurality of voltage values. The semiconductor switch 7 is turned on by applying a control signal between the gate and the source of the semiconductor switch 7 in the photovoltaic power generation apparatus corresponding to the value.

  Next, operation | movement of the solar energy power generation system of Example 2 comprised in this way is demonstrated.

  First, currents flowing through the plurality of solar power generation devices 4 a-1 to 4 a-4 are detected by the plurality of current detection resistors 8-1 to 8-4, and these currents are input to the control circuit 10.

  Based on the plurality of current values from the plurality of current detection resistors 8-1 to 8-4, the control circuit 10 has the smallest current value among the plurality of current values, for example, the smallest flowing through the current detection resistor 8-1. By applying a control signal between the gate and the source of the semiconductor switches 7-2 to 7-4 in the solar power generation devices 3a-2 to 3a-4 corresponding to the remaining current values excluding the current value, The gap between the gate and the source is made substantially zero, and the semiconductor switches 7-2 to 7-4 are turned on. For this reason, the voltage of the solar power generation devices 3a-2 to 3a-4 is brought close to the voltage of the solar power generation device 3a-1.

That is, the power generation amount of each of the solar power generation devices 4a-1 to 4a-4 is compared, a part of the solar battery blocks of the solar power generation device with a large power generation amount is short-circuited, and the terminal voltage is reduced. By reducing the terminal voltage of the solar power generation device, the power generation amount other than the solar power generation device with low power generation voltage is reduced by aligning each line voltage and obtaining the power generation amount from the solar power generation device with low power generation voltage. Even if the amount is subtracted, the power generation efficiency of the entire photovoltaic power generation system can be improved by turning on the semiconductor switch 7 under the condition that the amount of power generation from the line of the photovoltaic power generation device having a low generation voltage is higher.
In addition, this invention is not limited to the solar power generation device and solar power generation system of Example 1 and Example 2. For example, it is possible to adjust a time constant and a threshold value for turning on / off the semiconductor switch 7 by inserting a capacitor or a resistor between the gate and the source of the semiconductor switch 7.

  The present invention is applicable to storage batteries, inverters, and the like.

1,1a Solar cell element
2 Diode 3, 3a, 3a-1 to 3a-4 Solar cell block 4, 4a, 4-1 to 4-n Photovoltaic power generation device 5 Load 6-1 to 6-n Diode
7,7-1 to 7-4 Normally-on type switch
8-1 to 8-4 Current detection resistor 10 Control circuit

Claims (2)

One or more solar cell elements connected in series and the one or more solar cell elements are connected in parallel and turned off when sunlight is irradiated and turned on when the sunlight is not irradiated the composite element composed of a semiconductor switch, Ri Na connected to each other in series,
The said semiconductor switch consists of a normally-on type switch, and connects a 2nd solar cell element between the gate-source of the said semiconductor switch, The solar power generation device characterized by the above-mentioned. A parallel circuit in which a plurality of photovoltaic power generation devices according to claim 1 are connected in parallel;
A plurality of detection units provided corresponding to the plurality of solar power generation devices, detecting currents or voltages of the plurality of solar power generation devices and outputting a plurality of detection signals;
Based on a plurality of detection signals from the plurality of detection units, a control circuit for turning on one or more of the semiconductor switches in the plurality of photovoltaic power generation devices,
A photovoltaic power generation system comprising:

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