JPS5996876A - Inverter device - Google Patents

Abstract

PURPOSE:To efficiently convert by a simple circuit into an AC voltage near a sinusoidal wave by suitably selecting, converting and supplying the voltages of a plurality of battery units. CONSTITUTION:DC powers which are obtained from battery units 1A-1C such as solar battery or fuel battery are converted by switching elements 3-6 such as thyristors into AC powers, and supplied to a load 8. In this case, a plurality of battery units 1A-1C are employed, the DC voltage is applied to an inverter device through a switching circuit 2, this switching circuit 2 is switched and connected at the time interval of 1/6 of the half wavelength of a sinusoidal wave obtained as the AC output by a control circuit 2a by sequentially selecting the output terminal 2b from an input terminal 2e to 2d, 2c and from 2c to 2d, 2e. This switching circuit 2 efficiently converts to the AC voltage near the sinusoidal wave.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inverter device]7, and particularly relates to an inverter device that converts DC power obtained from a solar cell or a fuel cell into AC power.

Recently, the gods have been considering the effective use of solar energy, and are they converting solar energy into turtle power? A power supply system is being developed. When using solar cells in this type of system, an inverter device is required to convert the DC voltage obtained from the solar cells into AC voltage.

Further, a power supply system using a fuel cell is also being researched, but this system also requires an inverter device. As a conventionally known inverter device, a sine wave alternating current (DC) is used to generate high frequency pulses whose pulse width is modulated in a sinusoidal waveform by turning on and off a DC voltage using a switching element, and to pass this high frequency pulse through a filter circuit. Pulse width modulation (PWM) to obtain voltage
There is a method. However, this inverter device has the disadvantage that the circuit is complicated because it requires a pulse width modulation circuit, and the conversion efficiency is low because the loss in the filter circuit is large.

An object of the present invention is to provide an inverter device that can efficiently convert DC power obtained from a battery unit such as a solar cell or a fuel cell into AC power using a simple circuit.

The inverter device of the present invention will be described in detail below with reference to the drawings.

Figure 1 shows the basic configuration of the present invention. In the figure, IA, IB, and 1c are battery units such as solar cells that have the same DC output voltage. Each battery unit is a single battery cell or a combination of battery cells. The battery unit (IA, IB, and IC) are connected in series.

Reference numeral 2 denotes a control circuit 2a that sets a time limit for the switching operation, and a switching circuit that performs the switching operation, and this switching circuit is a thyristor or a GTO.

It consists of transistors, etc. The switching circuit 2 is configured to appropriately switch and connect the output terminal 2b to the input terminals 2 c and 2 d y 2 e based on a control signal given from the control circuit 2 a. The input terminal 2c is an example of the positive electrode of the battery unit 1G, and the input terminal 2d is the battery unit) I
The input terminal 2e is connected to the positive electrode of the battery unit IA and the negative electrode of the solar cell unit IB, respectively. 3,4.
5 and 6 are switching elements consisting of switching elements such as Cyrisk, transistors, GTO, etc. Switching elements 3 and 4 are connected in series, and both ends of the series circuit are connected to the input terminal 2b and the negative electrode of the battery unit (IA). connected to. ing. Furthermore, the switching elements 5 and 6 are connected in series, and both ends of the series circuit are connected to the input terminal 2b and the battery unit (L).
It is connected to the negative electrode of A. These switching elements 3.4.5 and 6 are controlled by control signals from the control circuit 2a,
When the number of operations of the switching circuit 2 reaches a predetermined value, the switching elements 3, 6 or 4, 5 are rendered conductive at the same time. In this example, the switching elements 3 to 6 constitute a switching circuit. 7 and 7' are output terminals, one output terminal 7 being connected to the connection point between the switching elements 3 and 47, and the other output terminal 7' being connected to the connection point between the switching elements 5 and 6.

These components constitute the inverter device of the present invention. Note that 8 is a load connected to the output terminal 7.7'.

Next, the operation of converting DC power to AC power using the inverter device of the present invention will be explained with reference to FIGS. 1 and 2. In the circuit shown in FIG. 1, the switching circuit 2 sequentially selects and connects the output terminal 2b from the input terminal 2e to the input terminals 2d and 2c at a time interval of 1/6 of the half wavelength of the sine wave obtained as an AC output. However, when switching to the input terminal 2c, the switching operation is repeated in which the output terminal 2b is sequentially switched from the input terminal 2c to the input terminals 2d and 2e after waiting for the half-wavelength stirrup time to pass. shall be. On the other hand, the output terminal 2b of the switching circuit 2 is connected to the input terminal 2e.
When a predetermined time period has elapsed after the switching elements 4 and 5 have been switched and connected, if the switching elements 3 and 6 have been conductive, they are made non-conductive and at the same time the switching elements 4 and 5 are made conductive.
, 5 are conductive, they are rendered non-conductive and the switching element 3.6 is rendered conductive.

Therefore, if the switching circuit 2 now selects the input terminal 2e and the switching elements 3 and 6 are conductive, as shown in FIG. , 7', the output terminal 7 side is outputted as a positive potential. Then, the half-wavelength I of the AC output waveform is
After time A has elapsed, that is, at time tl, the switching circuit 2 performs a switching operation to switch and connect the output terminal 2b to the input terminal 2d. Therefore, the DC voltages EIA and EIB of battery units IA and IB are connected between output terminals 7 and 7.
The voltage that is superimposed on the two is output. Furthermore, when time t1 reaches t2, the switching circuit 2 selects the input terminal 2c and connects it to the output terminal 2bK, and the battery unit LA,
1B voltage EIA, EIB plus battery unit IC
A superimposed voltage EIC is output. ``Then, at time t3, the switching circuit 2 selects the input terminal 2d, connects it to the output terminal 2b, and connects it to the battery unit LA.
, IB are outputted from the output terminals 7, 7'.

Furthermore, at time t4, the switching circuit 2 connects the input terminal 2.
e is selected to output the voltage EIA of only the solar cell unit IA between the output terminals 7 and 7'. Furthermore, after the switching circuit 2 selects the battery output terminal 2e and a half-wavelength IA time has elapsed, the switching elements 3 and 6 become non-conductive, and immediately the switching elements 4 and 5 become conductive.

As a result, the polarity of the DC voltage output to the p output terminals 7, 7 is reversed, and the output terminal 7' becomes a positive potential.

Thereafter, the switching operation described above is performed and the same voltage as described above is output, and an alternating current voltage whose output voltage value changes with the passage of time is generated between the output terminals 7, 7. Similarly, the switching circuit 2 and the switching element 3
, 4, 5.6 are repeated. As a result, a voltage having a waveform approximately like a sine wave is output between the output terminals 7 and 7'. This output voltage is further processed by a waveform shaping filter (not shown).
By passing it through, it is possible to get even closer to a sine wave,
DC voltage from solar cells can be converted to AC voltage. In this example, the battery unit) IA.

Although the output voltages of the IB and IC are made equal, the voltage values of the husband and wife may be made different in order to reduce the distortion of the voltage waveform obtained as AC. Furthermore, the time intervals of the switching operations of the switching circuit are not limited to equal intervals;
Of course, it should be selected appropriately in relation to the number of battery units, etc.

FIG. 3 shows another configuration example of the inverter device of the present invention, in which the switching circuit 2 selects the battery units (IA, IB, and IC) in the examples of FIGS. 1 and 3. battery unit) IA.

IB and IC are used individually. Therefore, the battery units IA, IB, and IC have different output voltages.

The voltage values are selected in order of increasing IC. The switching circuit consisting of the switching circuit 2 and the switching elements 3, 4, 5.6 operates in the same manner as shown in FIG.

In FIG. 3, the switching circuit 2 is now connected to the input terminal 2.
When e is selected, the voltage EIA of the battery unit IA is outputted between the output terminals 7 and 7' from time to, and the output terminal 7 side becomes a positive potential.

At time t1, the switching circuit 2 selects the input terminal 2d, so that the voltage of the stain pond unit) IB changes to the output terminal 7,
7', and further at time t2, the switching circuit 2 selects the input terminal 2C, and the solar cell unit) IC
voltage is output between output terminals 7 and 7'. Thereafter, the switching circuit 2 selects the input terminal 2d at time t3 and the input terminal 2e at time t4, and outputs the output voltages EIB and EIA between the output terminals 7 and 7. Then, at time t8, the switching elements 3 and 6 are made non-conductive and the switching elements 4 and 5 are made conductive, thereby reversing the voltage polarity of the battery unit output between the output terminals 7 and 7. The switching circuit 2 is operated to perform a switching operation to obtain an alternating current voltage whose polarity is inverted every half wavelength.

Although three battery units were used in each of the above embodiments, the number is not limited in any way. Of course, by increasing the number of battery units, the converted AC voltage waveform can be made closer to a sine wave. Furthermore, the present invention can be applied not only to solar cells but also to cases where fuel cells and the like are used. It goes without saying that it can also be applied to three-phase alternating current.

As described above, according to the present invention, an alternating current voltage close to a sine wave is obtained by appropriately selecting the voltages of a plurality of battery units. It has the advantage of being able to efficiently convert a DC voltage to an AC voltage close to a sine wave with a simple circuit consisting of a combination of the following.

[Brief explanation of the drawing]

1 and 3 are block diagrams showing different configuration examples of the present invention, and FIGS. 2 and 4 are waveform diagrams for explaining the operation of the impark device shown in FIGS. 1 and 3, respectively. be. 1A-IC...Battery unit, 2...Switching circuit, 3-6...Switching element.

Claims (1)

[Claims] a plurality of battery units; a switching circuit that selectively switches the voltage of the individual battery units or the sum of the high voltages of the battery units; An inverter device comprising: a switching circuit for selectively supplying voltage or negative voltage; said switching circuit performs a switching operation at appropriate time intervals so as to obtain all AC output to said output terminal.