JPH0496661A - Ac power generating circuit - Google Patents

Abstract

PURPOSE:To halve DC power supply voltage and the withstand voltage of an amplifying element without employing two types of complementary amplifying elements arranged so that an AC power is fed from the output of a bridge type switching circuit in the vicinity of zero point of full-wave rectified output voltage from the amplifying element. CONSTITUTION:A DC power supply having peak level identical to that of an AC output voltage is provided, an amplifying element (dropper) is connected in series therewith to output an amplified full-wave rectified waveform which is then inverted alternately through a bridge switching circuit thus producing a mine wave output. Since the amplifying element(dropper) is applied with DC power supply voltage. i.e., the voltage having the waveform of dropper INPUT, the applying voltage is halved as compared with a complementary pair. According to the constitution, withstand voltage of the amplifying element can be halved as compared with a conventional one.

Description

[Detailed description of the invention] The present invention relates to an AC power generation circuit.

Conventionally, various systems have been used as circuits that generate AC power. For example, from a sine wave signal generation circuit to a complementary bearer field effect transistor (FET)
) or bipolar transistors for DC amplification. In a circuit based on such a system, when the AC output voltage is selected to be a relatively high voltage, for example, about 280 V, it is necessary that the withstand voltage of the complementary bearer transistor used be 1,000 V or more. Currently, it is difficult to obtain high-voltage transistors using complementary bare. Therefore, a method has been taken in which transistors of the same type are connected in a totem pole connection, but the circuit becomes complicated.

In addition, in the conventional circuit shown above, the DC power supply voltage for DC amplification is ±500V (1
, 0OOV) or more.

The present invention solves the problems of the conventional circuit described above, and provides an AC power generation circuit that can reduce the DC power supply voltage and the withstand voltage of the amplification element by half without using two complementary types of amplification elements. For the purpose of providing.

FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention, and T1
is an isolation transformer, DBl is a rectifier circuit, C1 is a smoothing capacitor, and dropper is an amplification element (FET here) OP
AMP is an operational amplifier, FETI, FET2, FET3,
FET4 is an FET and constitutes a bridge switch circuit. Additionally, a full-wave rectified waveform oscillation circuit and voltage control block are included. AC input isolation transformer T1
and output from the secondary side. This corresponds to TI INPUT and TI 0UT in the waveform timing diagram in Figure 2.
PUT represents the AC voltage waveforms on the primary side and secondary side of the isolation transformer T1, respectively.

Further, the AC voltage of T10UTPUT is rectified and smoothed by the rectifier circuit DB1 and the smoothing capacitor CI. The smooth DC current is shown at dropper INPUT in FIG. The voltage value of the dropper I NPUT is set to a value greater than or equal to the peak value of the desired AC output voltage.

On the other hand, for example, a full-wave rectified waveform signal formed by a full-wave rectified waveform generation circuit constituted by a ROM, a D/A converter, etc., an output voltage control block, and an OPAMP is applied as a control input to an amplification element represented by a dropper.

In other words, the full-wave rectified waveform signal is amplified, and the second
A voltage as shown in the waveform of the dropper 0UTPUT in the figure is generated on the output side of the dropper. Next, the control switches SWI and SW2 are turned on at the timing of OV of the dropper 0UTPUT waveform so as to conduct the FET ] and FET2 that constitute the bridge switch circuit, and SW3 is turned on at the timing of oV of the next dropper 0UTPUT waveform.
and turns on SW4 to make FET3 and FET4 conductive. By alternately turning on and off FET1 and FET2, and FET3 and FET4 at the timings of 2 and 4 in this manner, a sine wave AC output such as AB-OUTPUT in FIG. 2 can be obtained between AC output terminals AB.

As mentioned above, in the circuit of the present invention, a DC power supply equal to the peak area of the desired AC output voltage is provided, an amplification element (dropper) is connected in series to the DC power supply, and an amplified full-wave rectified waveform is output. However, a sine wave output is generated by alternately inverting the signals using a bridge switch circuit.

Therefore, the amplifying element (dropper) is powered by a DC power supply, i.e.
The voltage of the waveform of the dropper I NPUT in Fig. 2 is applied, and 172% of the applied voltage in complementary repair etc.
becomes. Moreover, this makes it possible to select the allowable withstand voltage of the amplifying element to be used that is 1/2 that of the conventional circuit.

Furthermore, when selecting an FET as an amplification element, when selecting an N-channel type, a P-channel type, or a bipolar transistor, it is not necessary to use both NPN type and PNP type, and only the type that is easily available can be selected.

It is preferable to turn on and off the switches SW1.2 and SW3.4 accurately at OV, but strictly speaking, it is close to 0.

In actual applications, the circuit configuration of the embodiment shown in FIG. 1 may undergo design changes such as modifications and additions.

The configuration of the DC power source may be obtained from a rectifier circuit and a smoothing circuit as shown in Figure 1, or from a battery or converter output.
AB-OUTPUT may be further rectified or connected to other functional circuits.

As described above, by carrying out the present invention, in order to obtain accurate sine wave AC power, it is not necessary to use a large number of different types of elements such as complementary repair, and power can be generated by adjusting the power supply voltage to about the peak of the desired AC voltage. It can be used to construct circuits and can be used in a wide range of applications, such as power supplies for inspection equipment, making it highly effective for industry.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram of an embodiment of the present invention, FIG. 2 is a waveform timing diagram of FIG. 1, and T1 is an isolation transformer, DB
I is a rectifier circuit, CI is a smoothing capacitor, dropper is an amplification element, OPAMP is an operational amplifier, FET1.2.3
．． 4 is the bridge switch circuit, SWl, 2.3.4 is the control switch? be.

Claims (1)

[Claims] A bridge type switch circuit is connected in series to the DC power supply via an amplifying element, and a full-wave rectified waveform generating circuit is provided, and the signal is used as a control input of the amplifying element, and the full-wave rectified output voltage of the amplifying element is An alternating current power generation circuit, characterized in that alternating current power can be supplied from the output side of the bridge type switch circuit near zero.