JPS5932020A - Controller for solar battery driving power converter - Google Patents

Abstract

PURPOSE:To obtain a controller of a simple structure which has high performance and high reliability, by connecting a dummy resistance to a solar battery and actuating a power converter when the terminal voltage of the dummy resistance reaches a level that can actuate the power converter. CONSTITUTION:The 1st comparator 8 compares the terminal voltage of a dummy resistance 15 which is detected by a voltage detector 6 with the set voltage of a starting voltage setter 7 which sets the voltage to enable to start to an inverter 2. The comparator 8 works when the terminal voltage of the resistance 15 is higher than the set voltage. Then a relay 9 is driven, and contacts 9b and 9a are opened and closed respectively to start an inverter 2. The voltage detected by the detector 6 is compared with the set voltage of the 2nd voltage setter 10. The deviation voltage obtained from this comparison is converted into a function suited to the voltage characteristics of a load 3 by a function generator 14 through amplifiers 12 and 13 in order to control the inverter 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a power converter, and more particularly to a control device for a power converter using a low output capacity power source, such as a solar cell sound power source.

The voltage drawn from the photovoltaic solar cell plate DC power supply is related to the sunlight incident on the cell plate. Therefore, the voltage taken out from the battery plate changes significantly as the solar energy incident on the battery fluctuates over a long period of time or a short period of time. The available power per unit area of a solar panel varies from zero value at night to a maximum value during a clear day.

Energy conversion systems have been proposed that include a solar cell, a static power conversion device such as an inverter, and a load connected thereto. In such a system, the output of a solar cell varies greatly depending on the amount of sunlight and battery temperature, so if there is little solar radiation, even if there is voltage, the inverter's output will change significantly. When the inverter starts, the voltage drops and the inverter immediately stops. Hence the control of the converter? Efficient use of solar energy cannot be achieved unless done properly.

The present invention has been made in view of the above-mentioned points, and its purpose is to provide a high-performance power conversion system that can efficiently utilize solar energy even when the amount of sunlight changes or the battery temperature changes rapidly. A control device that is easy to configure? It is to provide.

Below, the control device fe? of the solar battery drive conversion device according to the embodiment of the present invention will be described. r, will be explained with reference to FIGS. 1 and 2.

@1 indicates the control device 7 of the power converter, l is the solar cell, % λ is the driven part, such as the inverter, and 3 is the load of the inverter 2, such as the dielectric motor for driving the pump. Out.

≠ is the switching controller, % S is the phase controller for controlling all operations of the inverter λ, and B is the output voltage of the solar cell? The voltage detector 7 is a starting voltage setting device for setting the fz fJ pressure required to start the inverter 21r. There is a first comparator that uses the voltage detection signal of the voltage detector I4 and the set voltage of the starting voltage setter 7.
In order to change the hysteresis characteristic, it is provided. 9 is a relay controlled by the output signal of this comparator ♂, 10
is the second voltage setter, // is the second voltage setter 10
The setting voltage signal and the detection signal of voltage detection I4? This is the second comparator for input. 12 is the deviation signal from the second comparator/l? The first input amplifier controls the constant voltage of the loop (
+1?1'? This is what we do. Is 13 the output of the first amplifier? Input and tL? This is a second amplifier that amplifies the voltage and also sets the upper and lower limit voltages.

Is the input voltage from the second amplifier/3? A function generator that converts the voltage function to match the load, such as a 7t inverter! When using a pump as a load.

Does this pump have a cubic characteristic of output relative to inflow input? Therefore, the function generator/1fiK has input-output characteristics of the cube root? It's a must have.

Particularly, the present invention is characterized by connecting a dummy resistor is2 to the solar cell, as shown in FIG.

The resistance value of this dummy resistor/3 is the DC input required to provide the minimum load for the case t when the inverter λ has a load.
The value should be set so that a current of the same value as the current can flow.

Is the dummy resistor 15 the normally closed contact 9b of the relay 9? It is connected in parallel to the solar cell l via the

A normally open contact fa of the relay 7 is used as a start/stop command switch for the inverter 2.

In a control device for a power conversion device having the above configuration.

The terminal voltage of the dummy resistor 15 is detected by the voltage detection I4. , Is the voltage detector tI3 voltage the voltage at which inverter 2r can be started by the first comparator ♂? Set.

Compare with the set voltage of the starting voltage setter 7.

That is, when the terminal voltage of the dummy resistor 15 is greater than the set voltage, the first comparator ♂ is activated and the relator is activated.

relay? When the inverter 2 is operated, the contact 9b is opened, the contact 7a is turned on, and the inverter 2 is started.

On the other hand, the detected voltage of the voltage detection I4 is detected by the second voltage setter 10.
It is compared with the set voltage of , and the deviation voltage 7 is inverted and amplified. The upper and lower voltage limits of the amplified voltage signal of the first amplifier/co are set by the second amplifier 13. The output voltage of the second amplifier 13 is converted into a function adapted to the voltage characteristics of the load 3 by a function generator/da. The output signal of the function generator lda is input to the phase controller A, and the inverter 2 is controlled according to the signal of the function generator /q. Inverter tacho is solar battery/
Ic is regulated in advance by the first comparator ♂ so that it operates when the voltage of Ic is 250 (V) and stops at 220 (V).

If the voltage of the solar cell / has not reached a level that allows full operation of the inverter tacho, the output of the first comparator r? Is it Rin-9? A dummy resistor is connected as a load of 157 solar cells/! as inactive, and this dummy resistor/! ;VC inverter 2
is the minimum load? Current equivalent to load current when negative? Let it flow. When the voltage of the solar cell 1 rises to a level at which the inverter 2 can operate with the dummy resistor/3f load in this way, the freelator is operated by the output of the first comparator and the contact 9b is opened. Dummy resistance!
When j5 is disconnected from the battery, contact 9a is turned on and inverter λ is started normally. At this time, the straight line in Figure 2 °C. The inverter λ is controlled 7 at the maximum power of each characteristic as the solar radiation needle t parameter shown by the intersection with . Figure 2 shows the voltage ('V)-current (1) characteristics of the solar cell and the output ff.
) - Current potential) It is a characteristic diagram showing the correspondence relationship with %.

In conventional equipment, when the voltage of the solar cells drops, the inverter turns off, and when the voltage rises, the inverter turns on, causing the so-called hunting phenomenon.
According to Vc, a dummy resistor/3f is connected to the solar cell, and the dummy resistor 15 has the minimum load? What value of current should be supplied to the minimum load when the load is negative? Is it possible to detect the full voltage across the dummy resistor IS and start or stop the inverter 42? It can be prevented.

Also as an on-off operating condition for the inverter tacho.

Toe's on level is 250 (claw off level fi!2
Since the first comparator has a hysteresis characteristic of 7 so that the voltage is 20 (V), is it stable in operation? can be improved. Furthermore, in general, when the load of the inverter λ is a pump, for example, the gain of the inverter control system changes significantly between the minimum output and the maximum output.

As is well known, the operation of the inverter becomes unstable especially in the high gain region. However, in the above-mentioned embodiment, as a means to solve such an unstable phenomenon during operation, the input-output characteristic of the cube root & the loop gain of the control system - Jjs is constant over the entire operating range. I'm trying to make it happen. So, does this improve operational stability? As explained above, according to the present invention, when the voltage of the solar cell reaches a value that allows the power converter 7 to be driven.

A dummy resistor having a resistance value equal to the DC input current when the power converter is at the minimum load is connected to the battery, and the total voltage across this dummy resistor is detected. and give it to a comparator with hysteresis characteristic 7,
The output of this comparator is used to control the pre-impartan. According to the present invention, it is possible to obtain a control device for a solar battery-driven power converter that has a simple structure and high reliability, and its effects are great. .

[Brief explanation of the drawing]

Figure 2 is a diagram of the power converter control system according to the embodiment of the present invention; :
Current characteristics and output current! Samurai? FIG. /...thick mt'r: i pond 1.2...inverter,
3...Load, S...Phase fb controller, t...Voltage detection 2 Huff...Start '1' pressure setting device, Za...1st comparator, 9...Relay, 10...7A2't,
, :Pressure setting device, /C...Second comparator, 12...First
/3...second amplifier, lq...function generator. Figure 1 122- Figure 2

Claims (1)

[Claims] Thick 1j% 'F is a pond and this solar cell is moving 1
What is a dual power converter and the load that is powered by this power converter?
In an energy conversion system with a dummy resistor in the solar cell? When the terminal voltage of this dummy resistor reaches a voltage at which the power converter can operate, the 11 power converters? A way to start? Have you set it up? A control device for a solar battery-powered power converter.