JPH08205545A - Power source - Google Patents

Abstract

PURPOSE: To provide a power source in which a power source voltage change can be compensated and substantially constant output can be supplied to a load. CONSTITUTION: The power source comprises an inverter 5 for converting a pulsating DC voltage rectified from an DC power Vs by a rectifier DB to an AC high-frequency voltage output by turning ON, OFF at least one switching element Q1 to supply it to a load F, and a controller 3 for maintaining the switching frequency of the element Q1 substantially constant with respect to the change of the power Vs to maintain the high-frequency output of the inverter 5 substantially constant. Thus, the power source in which the power source voltage change can be compensated and the substantially constant output can be supplied to the load can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device.

[0002]

2. Description of the Related Art Conventionally, a power supply device having an inverter circuit for converting a pulsating DC voltage obtained by rectifying an AC power supply by a rectifier DB into an AC high frequency voltage output and supplying the load to a load is well known, and also has an input. A power supply device having an inverter circuit that improves current distortion is also well known. As an example thereof, there is one disclosed in Japanese Patent Laid-Open No. 5-38161,
The circuit diagram is shown in FIG. (First Conventional Example) However, the first conventional example charges the capacitor C1 serving as the power source of the inverter circuit 5 while improving the distortion of the input current Iin due to the resonance operation of the inverter circuit 5, so that the unloaded state, and A first problem arises in that the voltage VC1 across the capacitor C1 is boosted by the resonant operation of the inverter circuit 5 due to changes in the characteristics of the load.

As means for solving the above-mentioned first problem,
A constant output circuit that suppresses fluctuations in the high frequency output of the inverter circuit 5 is well known. An example of the circuit is shown in FIG. 8 and an operation waveform diagram thereof is shown in FIG.

The difference from the first conventional example shown in FIG. 7 is that a high frequency cutting diode D4 is provided at one end of the output of the rectifier DB.
Are connected in series, the pulsating current DC voltage of the output of the rectifier DB is detected by the voltage detection unit 1 of the resistors R1 and R2, and the divided voltage E1 is input to the power supply voltage compensating circuit 2, and the oscillator IC2 (for example,
The switching elements Q1 and Q2 are controlled via the oscillator IC4046 manufactured by NEC and the driver IC1 (for example, the driver ICIR2111 manufactured by IR), and the capacitor C1 is controlled.
The control unit 3 is configured to control the voltage VC1 across both terminals, and the same configurations as those of the other first conventional example are denoted by the same reference numerals and the description thereof will be omitted.

Here, the voltage VC1 across the capacitor C1
It is difficult to determine whether the fluctuation of AC voltage is due to the fluctuation of the AC power supply Vs or the characteristic change of the load F. Therefore, the voltage detection unit 1 detects the pulsating DC voltage and changes the fluctuation of the AC power supply Vs. Was detected.

The power supply voltage fluctuation compensating circuit 2 compares a voltage E1 and a voltage E2 obtained by dividing the external power supply Vcc by a resistor with a comparator I.
The output is compared by C3 and input to the base of the switching element Q3, and the resistors R5, R6 and R7, the switching element Q3
The signal E3 is controlled by controlling the voltage E3 determined by the above, and a signal is input to the pin 6 of the oscillator IC2.

The driver IC 1 has a switching element Q.
1 and Q2 are to be driven. A diode D5 is connected between the 1st and 8th pins, a capacitor C9 is connected between the 8th and 6th pins, and the 4th pin is connected to a switching element Q1.
No. 7 is connected to the base of the switching element Q2, No. 6 pin is connected to the connection point of the switching elements Q1 and Q2, and No. 3 pin is grounded to the ground G.
It operates according to the output signal of the oscillator IC2.

The oscillator IC2 has a fifth pin and a ground G.
The frequency is determined by inputting the output of the power supply voltage variation compensating circuit 2 to the pin C6 connected between the capacitor C8 and the output signal of which the duty is determined by the pin 1 and the pin 14. In addition to the output from the No. pin to the driver IC 1, the No. 8 pin and the No. 9 pin are connected to the external power supply Vcc, and the No. 2 pin, the No. 3 pin, the No. 4 pin, the No. 7 pin, the No. 11 pin, the No. 12 pin. The pin is grounded to the ground G. Pin 1 and pin 14 are short-circuited by the switching element Q4 to stop the oscillation of the oscillator IC2, and when the voltage E3 is lowered, the frequency of the output signal is reduced. The higher the voltage E3, the lower the frequency of the output signal.

Next, the operation will be briefly described with reference to FIG. As shown in FIG. 9A, when the AC power supply Vs rises, that is, the voltage E1 rises and becomes larger than the voltage E2,
As shown in (b), the comparator IC3 outputs a high (H) level signal and the switching element Q3 is turned on. When the switching element Q3 is turned on, the resistor R7 is short-circuited and the voltage E3 decreases as shown in FIG. 9 (c). When the voltage E3 decreases, the frequency of the output signal of the oscillator IC2 increases as shown in FIG. 9 (d).

When the voltage E1 becomes larger in the range higher than the voltage E2, the ON time of the switching element Q3 becomes longer and the voltage E3 lowers longer, so that the oscillator I
It takes longer for the frequency of the output signal of C2 to increase, and suppresses an increase in the high frequency output of the inverter circuit 5 via the driver IC1.

When the voltage E1 becomes smaller in the range higher than the voltage E2, the ON time of the switching element Q3 becomes shorter and the time when the voltage E3 drops becomes shorter, so that the frequency of the output signal of the oscillator IC2 becomes higher. Becomes shorter, and the high frequency output of the inverter circuit 5 is increased via the driver IC 1.

Further, as shown in FIG. 9A, an AC power source Vs
Is decreased, that is, the voltage E1 is decreased and becomes lower than the voltage E2, the comparator IC3 outputs a low (L) level signal and the switching element Q3 is turned off, as shown in FIG. 9B. When the switching element Q3 is turned off, FIG.
The voltage E3 rises as shown in (c). When the voltage E3 rises, as shown in FIG. 9D, the frequency of the output signal of the oscillator IC2 lowers, and the high frequency output of the inverter circuit 5 rises via the driver IC1.

In this way, with respect to the fluctuation of the AC power source,
It is possible to suppress fluctuations in the high frequency output of the inverter circuit 5.

Next, a third conventional example according to the present invention is shown in FIG.
11 shows the operation waveform diagram thereof. Second shown in FIG.
The difference from the conventional example is that the capacitors C4, C5, C8, the inductance elements L2, L3, and the diode D3 are omitted, and instead of the capacitor C1, the resistors R11, R12,
Diodes D11, D12, D13, capacitor C1
The partial smoothing circuit 4 including C1 and C12 is provided at the output end of the rectifier DB, and the same components as those of the second conventional example are denoted by the same reference numerals and description thereof will be omitted.

[0015]

However, in the second and third conventional examples, as shown in FIGS. 9 (d) and 11 (d), the frequency of the output signal of the oscillator IC2 is intermittently changed. Therefore, there is a second problem that the waveform of the load current IF flowing through the load F is distorted as shown in FIGS. 9 (e) and 11 (e).

The present invention has been made in view of the above problems, and an object thereof is to provide a power supply device capable of compensating for power supply voltage fluctuations and supplying a substantially constant output to a load.

[0017]

In order to solve the above problems, according to the invention of claim 1, it comprises at least one switching element, and the switching element is turned on / off so that the AC power supply is a rectifier. In a power supply device including an inverter circuit that converts a rectified pulsating DC voltage into an AC high-frequency voltage output and supplies it to a load, and a control unit that controls the output of the inverter circuit by controlling a switching element. The unit includes at least a voltage detection unit that detects the voltage of the AC power supply and a power supply voltage compensation circuit that gradually and substantially constants the output DC voltage in response to the voltage fluctuations detected by the voltage detection unit. The output frequency of the inverter circuit is gradually reduced by making the switching frequency of the switching element substantially constant against the voltage fluctuation detected by the Characterized in that it is intended to be substantially constant.

According to the second aspect of the present invention, the power supply voltage compensating circuit includes at least a capacitor, and the DC voltage to be output is gradually increased by the integrating action of the capacitor in response to the voltage fluctuation detected by the voltage detecting section. It is characterized in that it is substantially constant.

[0019]

According to the first aspect of the present invention, the pulsating voltage obtained by rectifying the AC power supply is detected by the voltage detection unit and input to the power supply voltage compensation circuit. The power supply voltage compensating circuit converts the input voltage into a DC voltage, and controls the DC voltage so that the DC voltage gradually becomes substantially constant. The frequency of the switching element of the inverter circuit is determined by the output of the power supply voltage compensation circuit, and the output of the inverter circuit is determined.However, when the output of the power supply voltage compensation circuit is gradually made approximately constant, the frequency of the switching element of the inverter circuit is It gradually becomes substantially constant, and the high frequency output of the inverter circuit gradually becomes substantially constant.

According to the second aspect of the present invention, the pulsating current voltage obtained by rectifying the AC power supply is detected by the voltage detection unit and input to the power supply voltage compensation circuit. The power supply voltage compensating circuit converts the input voltage into a DC voltage, and the DC voltage is controlled so as to gradually become substantially constant from a rectangular wave shape by the integration action of the capacitor. Then, the frequency of the switching element of the inverter circuit gradually becomes substantially constant, and the high frequency output of the inverter circuit gradually becomes substantially constant.

[0021]

【Example】

(Embodiment 1) FIG. 1 shows a block diagram of a first embodiment according to the present invention.

In the present configuration, the pulsating direct current voltage obtained by rectifying the alternating current power supply Vs by the rectifier DB is converted into an alternating high frequency voltage output by turning on and off at least one switching element Q1 and supplied to the load F. The control unit 3 keeps the switching frequency of the switching element Q1 substantially constant with respect to the fluctuation of the AC power supply Vs and makes the high-frequency output of the inverter circuit 5 substantially constant.

Here, the control unit 3 obtains the voltage E3, which is obtained by detecting the fluctuation of the AC power supply Vs and determines the switching frequency of the switching element Q1, by the integrating action of the capacitor C20 provided inside the control unit 3. , Gradually becoming almost constant.

(Embodiment 2) FIG. 2 shows a block diagram of a second embodiment according to the present invention.

The difference from the first embodiment shown in FIG. 1 is that the pulsating DC voltage obtained by rectifying the AC power supply Vs by the rectifier DB is turned on and off by the switching on and off of the switching elements Q1 and Q2 via the diode D4. The high-frequency voltage output is converted into a high-frequency voltage output, and the resonance operation of the capacitor C2 and the inductance element L1 supplies a high-frequency voltage with less distortion to the load F, while improving the distortion of the input current Iin to charge the capacitor C5. Since they are provided, the same configurations as those of the other first embodiment are denoted by the same reference numerals and the description thereof will be omitted.

(Embodiment 3) A circuit diagram of a third embodiment according to the present invention is shown in FIG. 3, and an operation waveform diagram thereof is shown in FIG.

This embodiment is a specific circuit example of the second embodiment shown in FIG. The difference from the second conventional example shown in FIG. 8 is that a capacitor C2 is provided at both ends of a series circuit of resistors R6 and R7.
0 is connected, and the same configurations as those of the other second conventional example are denoted by the same reference numerals and the description thereof will be omitted.

Next, the operation will be briefly described with reference to FIG. When the switching element Q3 is turned off, the charging current Ia flows to the capacitor C20 via the resistor R5, and the resistor R5
5, R6, R7, and the time constant consisting of the capacitor C20, the voltage VC20 across the capacitor C20, that is, FIG.
As shown in (c), the voltage E3 gradually rises. Also,
When the switching element Q3 is turned on, the discharge current I of the capacitor C20 is passed through the resistor R6 and the switching element Q3.
b flows, and the voltage VC20 across the capacitor C20, that is, the voltage E3 gradually decreases as shown in FIG. 4C due to the time constant of the resistor R6 and the capacitor C20.

When the above operation is repeated, the charge current Ia and the discharge current Ib become substantially equal due to the integral action of the capacitor C20, and the potential of the voltage E3 becomes substantially constant as shown in FIG. 4 (c). become. When the potential of the voltage E3 becomes substantially constant, the frequency of the output signal of the oscillator IC2 becomes substantially constant as shown in FIG. 4 (d), and the load current IF has a waveform with little distortion as shown in FIG. 4 (e). Is obtained.

In this embodiment, as shown in FIGS.
It may be used in the third conventional example shown in FIGS.

In all the above embodiments, the switching elements Q1, Q2 and Q3 may be MOSFETs or other switching elements, the load F may be a lighting load such as a discharge lamp, or any other type, and the inverter circuit 5 Other configurations may be used.

[0032]

According to the present invention, it is possible to provide a power supply device capable of compensating for power supply voltage fluctuations and supplying a substantially constant output to a load.

[Brief description of drawings]

FIG. 1 shows a block diagram of a first embodiment according to the present invention.

FIG. 2 shows a block diagram of a second embodiment according to the present invention.

FIG. 3 shows a circuit diagram of a third embodiment according to the present invention.

FIG. 4 shows an operation waveform diagram according to the above embodiment.

FIG. 5 shows another circuit diagram according to the above embodiment.

FIG. 6 shows an operation waveform diagram of another circuit diagram according to the embodiment.

FIG. 7 shows a circuit diagram of a first conventional example according to the present invention.

FIG. 8 shows a circuit diagram of a second conventional example according to the present invention.

FIG. 9 is an operation waveform diagram according to the second conventional example.

FIG. 10 shows a circuit diagram of a third conventional example according to the present invention.

FIG. 11 shows an operation waveform diagram according to the third conventional example.

[Explanation of symbols]

 1 Voltage Detection Section 2 Power Supply Voltage Fluctuation Compensation Circuit 3 Control Section 5 Inverter Circuit C Capacitor DB Rectifier F Load Q Switching Element

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshifumi Sakatani 1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.

Claims (2)

[Claims] 1. An inverter circuit comprising at least one switching element and converting a pulsating current DC voltage obtained by rectifying an AC power supply by a rectifier by turning the switching element ON / OFF to supply the AC high frequency voltage output to a load. And a control unit that controls the output of the inverter circuit by controlling the switching element, wherein the control unit includes a voltage detection unit that detects a voltage of the AC power supply, and the voltage detection unit. A power supply voltage compensating circuit for gradually making the output DC voltage substantially constant with respect to the voltage fluctuation detected by the voltage detector, and the switching frequency of the switching element with respect to the voltage fluctuation detected by the voltage detector. Is gradually made substantially constant, and the output of the inverter circuit is made gradually substantially constant. A power supply unit. 2. The power supply voltage compensating circuit includes at least a capacitor, and an integral action of the capacitor causes the DC voltage to be output to be substantially constant with respect to the voltage fluctuation detected by the voltage detecting unit. The power supply device according to claim 1, wherein