JPH05276762A - Sine-wave ac power supply circuit - Google Patents

Abstract

PURPOSE:To obtain a small-sized, lightweight sine-wave AC power supply with a high efficiency by providing a pulsating signal generator to modulate the AC power supply output into a pulsating waveform, and a polarity inverter to invert the polarity per half cycle of the pulsating waveform. CONSTITUTION:A pulsating signal generator 2 consists of a ROM as a storage means 4 in which amplitude data corresponding with the phase are stored in a digital value, a reference voltage generator 7 showing a voltage value corresponding with one bit of the amplitude data, and a D/A converter 5 that converts the amplitude data read out from the means 4 into analog signals having proper amplitude on the basis of the output voltage from the generator 7. Then the output signals from the converter 5 are inputted as a reference voltage into a DC power supply 1. On the other hand, the DC power supply 1 is permitted to be given a reference voltage from the outside of the power supply and further the reference voltage can be constructed so as to freely change the output of DC power supply through controlling is as necessary, thereby controlling the output operation through changing switching frequency or duty ratio based on the reference voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sine wave AC power supply circuit for generating a sine wave AC signal of arbitrary amplitude and frequency from a DC power supply, for example, a sine wave AC power supply circuit used for a performance tester of a protective relay. Regarding

[0002]

2. Description of the Related Art Conventionally, a sine wave AC power supply circuit has been composed of an oscillator that oscillates a minute sine wave signal and a linear amplifier that amplifies the sine wave signal generated by the oscillator.

[0003]

However, the above-mentioned conventional sine wave AC power supply circuit has a drawback in that the efficiency is poor due to a large loss of heat generated in the linear amplifier with respect to the input power. As a result, not only a large-capacity DC power source is needed for the output capacity (for example, about 4 times the power is required to supply 200 W of power), but also a heat dissipation means must be installed and the DC power is required. There was a drawback that the power supply was large and heavy. An object of the present invention is to eliminate the above-mentioned conventional drawbacks.

[0004]

In order to achieve this object, a characteristic configuration of a sine wave AC power supply circuit according to the present invention is a DC power supply and a pulsating current signal for modulating the output of the DC power supply into a pulsating waveform and outputting the pulsating current waveform. It is composed of a generator and a polarity inverter that inverts the polarity every half cycle of the pulsating flow waveform output from the DC power supply. In the above-mentioned configuration, the pulsating flow signal generator is composed of storage means in which amplitude data corresponding to the phase is stored and a D / A converter for converting the amplitude data read from the storage means into an analog signal. It is preferable that the DC power supply is configured by a switching regulator that generates an arbitrary DC current using the output signal of the D / A converter as a reference voltage.

[0005]

With the pulsating flow signal generator, the output voltage or current of the DC power supply is modulated into a pulsating flow waveform and output, and the polarity is inverted every half cycle of the pulsating flow waveform to generate an AC signal. It is possible to generate an AC signal with good conversion efficiency in a state where the waveform is not distorted without interposing a linear amplifier having a bad performance.

[0006]

According to the present invention, it is possible to use, for example, a switching regulator having high efficiency as a DC power supply and a polarity inverter which can be constituted by a switching element with low loss, without using a linear amplifier having low conversion efficiency. It has become possible to provide a highly efficient sine wave AC power source with small power loss and heat generation, small size, light weight and high efficiency.

[0007]

EXAMPLES Examples will be described below. As shown in FIG. 1, a sine wave AC power supply circuit includes a switching regulator as a DC power supply 1, and a pulsating flow signal generator 2 for converting an output voltage or current of the DC power supply 1 into a pulsating flow waveform for output.
And a polarity inverter 3 that inverts the polarity every half cycle of the pulsating flow waveform output from the DC power supply 1.

The pulsating flow signal generator 2 indicates a semiconductor memory (ROM) as a storage means 4 in which amplitude data corresponding to a phase is stored as a digital value, and a voltage value corresponding to 1 bit of the amplitude data. The reference voltage generator 7 and, as shown in FIG. 2, a D / A for converting the amplitude data read from the storage means 4 into an analog signal having an appropriate amplitude based on the output voltage from the reference voltage generator 7. The converter 5 is configured to input the output signal of the D / A converter 5 to the DC power supply 1 as a reference voltage.

The DC power supply 1 is constructed such that a reference voltage source is supplied from the outside of the power supply and the output of the DC power supply can be freely changed by appropriately controlling the reference voltage. The output is controlled by changing the switching frequency and the duty ratio according to the reference voltage.

Addresses 0 to 4095 are stored in the storage means 4 in association with phases 0 ° to 180 °. The A / D converter 5 has addresses 0 to 4095. Are configured to be repeatedly accessed at a set cycle, and the cycle of the output signal at the final stage is determined by the access cycle.

The output signal of the D / A converter 5 has a low voltage in the vicinity of 0 °, 180 ° and 360 ° in phase and a phase of 9 °.
The voltage increases near 0 ° and 270 °, and the switching period of the switching regulator is controlled by the output signal of the D / A converter 5, so that if the voltage of the D / A converter 5 increases, the output voltage or current Becomes higher, D / A converter 5
The lower the voltage, the lower the output voltage or current. That is, the cycle of the output signal of the final stage can be adjusted by adjusting the access cycle to the storage means 4, and the amplitude of the output signal of the final stage can be adjusted by adjusting the output voltage from the reference voltage generator 7. It can be adjusted.

The polarity inverter 3 is a switch means 8 for switching the polarity of the output voltage of the DC power supply 1 with respect to the load.
And a timing control means 9 for controlling the opening / closing of the switch means 8 in synchronization with the access timing of the address 4095 when being read from the storage means 4 to the D / A converter 5. ..

Another embodiment will be described below. In the above embodiment, the storage means 4 stores the basic amplitude data in which the addresses 0 to 4095 are associated with the phases 0 ° to 180 °, but the present invention is not limited to this.
The range of addresses and the range of phases are not limited to these, but are arbitrary, and for example, addresses from 0 to 2047 can be used.
The addresses up to the address may be configured to store and store basic amplitude data corresponding to phases 0 ° to 180 °.
In the above embodiment, an example in which a switching regulator is used for the DC power supply 1 has been described, but the present invention is not limited to this, and as shown in FIG. 3, a series regulator is used for the DC power supply 1 and its reference voltage input. The D / A at the terminal 10
You may input the output signal of the converter 5. The pulsating flow signal generator 2 generates a pulsating flow waveform that is a full-wave rectified sine wave, and may be generated by full-wave rectifying a sine wave obtained by an oscillator or the like. The polarity inverter 3 extracts a zero-cross point of a pulsating flow signal of the pulsating flow signal generator 2 and a transistor as a switching means 8 for switching the output polarity of the DC power supply 1, and switches the switching means 8 in synchronization with this. It may be constituted by the reversal timing means 9 for controlling the opening and closing of.

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a block diagram of a sine wave AC power supply circuit.

FIG. 2 is a signal waveform diagram of essential parts.

FIG. 3 is a circuit diagram of a main part showing another embodiment.

[Explanation of symbols]

 1 DC power supply 2 Pulsation generator 3 Polarity inverter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Watanabe 2-28-2 Shinmachi, Setagaya-ku, Tokyo Sakurashinmachi San Heights 202 (72) Inventor Mitsuo Igarashi 1790-14 (72) Inahara City, Saitama Prefecture Inventor Kida Toshihiko 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka Prefecture Osaka Gas Co., Ltd. (72) Inventor Hideo Inui 4-1-2, Hirano-cho, Chuo-ku, Osaka City, Osaka (72) Inventor (72) Invention Ichisei Suzuki 13-131 Noda, Nakagawa-ku, Nagoya-shi, Aichi (72) Inventor Hideo Ose 14th, Niigata, Oi-ji, Saya-cho, Kaifu-gun, Aichi Prefecture (72) Masahiko Takayama Plains, Osaka-shi, Osaka 1-22-17 Kamikita, Ku

Claims (2)

[Claims] 1. A DC power supply (1) and its DC power supply (1)
Signal generator (2) for modulating and outputting the output of the pulsating flow waveform, and a polarity inverter (3) for inverting the polarity every half cycle of the pulsating flow waveform output from the DC power supply (1). A sinusoidal AC power supply circuit composed of and. 2. The pulsating flow signal generator (2) is provided with a storage means (4) in which amplitude data corresponding to a phase is stored, and the amplitude data read from the storage means (4) is converted into an analog signal. And a D / A converter (5) for conversion, and the DC power supply (1) is composed of a switching regulator that generates an arbitrary DC using the output signal of the D / A converter (5) as a reference voltage. The sine wave AC power supply circuit according to claim 1.