JPH0322865A - Dc power source device - Google Patents

Abstract

PURPOSE:To prevent the deterioration of efficiency by a method wherein the optimum duty driving is effected while keeping the duty of a switching element or the voltage conversion ratio of the same inspite of the change of an AC power source voltage. CONSTITUTION:A reference voltage forming circuit 24 for obtaining a DC voltage, corresponding to the voltage of AC power source terminals 1, 2 or a rectifying circuit 8, as a reference voltage is provided. A circuit is constituted so as to form the control pulse of a switching element 15 based on the output of the circuit 24 and a differential signal forming circuit (differential amplifier) 23 for obtaining a voltage corresponding to a difference between a detecting voltage obtained from a voltage detecting circuit 20 and a reference voltage obtained from the reference voltage forming circuit 24. A control pulse forming circuit is constituted of a multiplier 29, a current detector 16, a comparator 31 and a flip flop 32 so that the duty of the switching element 15 is not changed in accordance with the change of the voltage of the AC power source terminals 1, 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a DC power supply device that can improve the current waveform without reducing efficiency even when the voltage in an AC input line changes. [Prior Art] In order to correct the distortion of the current waveform of an AC input line based on the on/off operation of a switching element such as a switching regulator or an inverter connected to a rectifier circuit,
A reactor is connected to the power supply line, and the switching element connected between the pair of DC output lines of the rectifier circuit is turned on and off.
It is known to perform off control (for example, Japanese Patent Application Laid-Open No. 63-1
90557). [Problem W1 to be Solved by the Invention] By the way, there are cases where the above-mentioned DC power supply device is not alternatively connected to a 100V AC power supply or a 200V AC power supply. A DC power supply is designed to obtain a constant DC output voltage regardless of input voltage fluctuations, so when the input voltage fluctuates, the duty of the switching element changes. In particular, the promotion chopper type DC power supply device is 100%
■When connected to an AC power supply, the duty increases,
Loss in the switching circuit increases and efficiency decreases. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a DC power supply device that can keep the duty of a switching element constant regardless of fluctuations in AC power supply voltage and prevent a decrease in efficiency. [Means for Solving the Problem] The present invention for achieving the above object includes an AC power supply terminal,
A rectifier circuit connected to the AC power terminal is connected in series with an AC power line between the AC power supply terminal and the rectifier circuit V@ε, or in parallel and/or in series with a DC output line of the rectifier circuit. and an inductance circuit element disposed on the output side of the rectifier circuit, which operates on and off with a cycle shorter than the cycle of the AC voltage of the AC power terminal, and stores energy in the inductance circuit element. a switching element that controls emission; a smoothing capacitor provided on the output side of the switching element; a voltage detection circuit that detects the DC output voltage smoothed by the smoothing capacitor; In a certain DC power supply device, a control circuit forms a control pulse for turning on and off the switching element based on the detected voltage, and supplies this control pulse to the switching element. a reference voltage forming circuit for obtaining a DC voltage corresponding to the voltage of the circuit as a reference voltage; and a reference voltage forming circuit corresponding to the difference between the detected voltage obtained from the voltage detection circuit and the reference voltage obtained from the reference voltage forming circuit. a difference signal forming circuit for obtaining a voltage; and a circuit forming a control pulse for the switching element based on the output of the difference signal forming circuit, the duty of the switching element being responsive to changes in the voltage of the AC power supply terminal. This invention relates to a DC power supply device characterized by being equipped with a control pulse forming circuit that is configured to follow and not change. It is preferable that the control pulse forming circuit consists of a nosepiece, a current detector, a comparator, and a flip cup, as in the embodiment.
[Function] In the above invention, when the AC power supply voltage becomes low, for example,
The reference voltage also becomes lower. As a result, even if the DC output voltage becomes low, the output of the difference signal forming circuit remains virtually constant without being affected by fluctuations in the AC power supply voltage. Therefore, the duty of the switching element does not substantially change in response to fluctuations in the AC power supply voltage. [Example] Next, a DC power supply device according to an example of the present invention will be described with reference to FIGS. 1 and 2. This device has, for example, 50
It has a pair of AC power terminals 1 and 2 to which a +12 commercial AC 'r4 source is connected. A high frequency removal filter 3 connected to the power supply terminals 1 and 2 consists of actuators 4 and 5 connected in series to the lines, and capacitors 6 and 7 connected between the pair of lines. A full-wave rectifier circuit 8 is connected to the output stage of the filter 3. One of the pair of DC lines 11 and 12 between the rectifier circuit 8 and the pair of DC output terminals 9 and 10 has an actuator 1 as an energy storage inductance circuit element.
3 and a backflow blocking diode 14 are connected in series. A switching element 15 consisting of an FET is connected between the output terminal of the reactor 13 and the lower DC line 12.
and a current detection resistor 16 as a current detector are connected. Smoothing capacitor 16 is reverse current blocking diode 1
It is connected between output terminals 9 and 10 in the output stage of 4. Note that no smoothing capacitor is connected between the rectifier circuit 8 and the switching element 15. A voltage detection circuit 20 consisting of resistors 18 and 19 is connected to an output terminal 9.
, 10, and this voltage detection line 21 is connected to one input terminal of a differential amplifier 23 serving as a differential signal forming circuit of the switching element control circuit 22. A reference voltage forming circuit 24 is connected to the other input terminal of the differential amplifier 23. The reference voltage type control circuit 24 is connected to the output line 1l of the rectifier circuit 8.
A reverse current blocking diode 25, a smoothing capacitor 26, and voltage dividing resistors 27 and 28 connected to the differential amplifier 23 provide a DC reference voltage corresponding to the average value of the AC power supply voltage.

The output terminal of the differential amplifier 23 and the rectified output line 11 are connected to the multiplier 29 . Therefore, the multiplier 29 provides an output in which the amplitude of the sinusoidal pulsating flow is controlled by differential output. A current detection line 30 led out from one end of the current detector 16 is connected to one input terminal of a voltage comparator 31. A multiplier 29 is connected to the other input terminal of the voltage converter 31. RS flip-flop 32 for generating control pulses
A trigger coil 33 electromagnetically coupled to the reactor 13 is connected to the set terminal S of , via a set trigger circuit 34 , and a converter 31 is connected to the reset terminal R via a reset trigger circuit FII 135 . The Q output terminal of the flip-flop 32 is connected to the switching element 1.
8 are connected to the control terminal (gate) of 5. 36 is a starting circuit, which connects a resistor 3 to the rectified output line 11.
capacitor 38 connected through capacitor 7 and capacitor 3
8 and a resistor 39, and a diode D2 connected between one end of the capacitor 38 and the upper end of the switching element 15. [Operation] Next, the operation of the circuit shown in Fig. 1 will be explained with reference to the waveforms shown in Fig. 2. When a sinusoidal AC voltage as shown in FIG. 2(A) is applied to the t source terminals 1 and 2, a full-wave rectified voltage waveform is obtained at the output stage of the rectifier circuit FI118.

This voltage waveform is transferred to the switching element 15 at a frequency sufficiently higher than the power supply frequency (more than several TLZ, for example, 20KLL).
z), the AC power terminals 1 and 2 will have the voltage shown in Figure 2 (B
) flows. Since the switching element 15 does not intermittent a smoothed direct current, but intermittent a sine wave pulsating current, the current waveform flowing through the power supply terminals 1 and 2 is as shown in Fig. 2 (B
), it becomes an approximate sine wave and the power factor is improved. The operation of each part will be explained in detail. When a voltage is obtained at the output stage of the rectifier circuit 8 by connecting the power supply, 36 capacitors 38 are charged as a starting circuit, and the set trigger time F
! A set signal is given to the flip-flop 32 via @34, and the switching element 15 is turned on by this Q output. When the switching element 15 is turned on, current flows from the reactor 13 and the switching element 15 to the switching circuit, and energy is stored in the reactor 13.

Since the reactor 13 is an inductance, Fig. 2 (
During the ON period of the switching element 15 shown in G), the current in the reactor 13 gradually increases as shown in FIG. 2(E). The current during this on period is detected by the current detection resistor 16 and becomes the input to the comparator 31, and is compared with the sine wave corresponding to the input power supply voltage given from the multiplier 29. When the triangular wave reaches the sine wave, the output of the comparator 31 is convert,
A reset signal is applied from the reset trigger circuit 35 to the flip-flop 32, the Q output of the flip-flop 32 becomes low level, and the switching element 15 is turned off. During the off-period of the switching element 15, the energy stored in the actuator l3 is transferred to the capacitor 17 via the diode 14. At this time, the capacitor 17 is charged with the voltage obtained by adding the voltage of the reactor 13 to the t source voltage, and the capacitor 17 is charged to a voltage higher than the power supply voltage. During the off period, the current in the beam actor is shown in Figure 2 (
E) decreases with time as shown by the dotted line. Note that if the amplitude of the pulsating current given from the multiplier 29 changes in accordance with the change in the angular position of the sine wave, the peak of the current flowing through the reactor 13 will also change accordingly, and the AC power terminals 1, 2, the approximate sine wave shown in Figure 2 (B) is obtained. When the release of energy from the reactor l3 is completed, a voltage in the opposite direction is generated in the secondary winding of the reactor 13, that is, the trigger winding 33, and this is applied as a trigger signal to the flip-flop 32, which starts switching again. Element 15 turns on. By the way, IOOV (first voltage) and 200V (second voltage) are alternatively connected to AC power supply terminals 1 and 2. If 200V is connected, the operation will be as shown in the section before t1 in Figure 2.2 In other words, in the case of 200V, the amplitude of the pulsating current in the output stage of the rectifier circuit will naturally become large, and the output terminal 9 , the output voltage obtained at 10 also becomes higher. As a result, the detection voltage input to the differential amplifier 23 also increases. l,
The reference voltage forming circuit 24 inputs the input voltage ('@source voltage)
is proportional to. Therefore, the output current of the multiplier 29 does not become very high. On the other hand, the current flowing through the reactor 13 during the ON period of the switching element 15 rises at a relatively steep slope, crosses the multiplier output, the output of the comparator 31 is inverted, and the switching element 15 is turned off. Now, if the duty of the switching element 15 is 50%, the voltage Vt of the reactor 13 becomes +■2 during the on period of the switching element 15, and becomes -V2 during the off period.
The power supplied to the load 41 connected to the output terminals 9 and 10 is kept constant, and the voltage of the power supply terminals 1 and 2 is set to 100V, for example.
If you do this, the operation after t1 in Figure 2 will occur. Since the load power is constant, the current in Fig. 2 (B) increases by the amount that the voltage in Fig. 2 (A) decreases. In this device, the step-up ratio is kept constant despite fluctuations in the input power supply voltage, so the DC output voltage decreases as shown in Figure 2 (C), and the DC output t current decreases as shown in Figure 2 (C). It increases as shown in D).
At this time, the voltage of the reference voltage forming circuit 24 decreases following the decrease in the power supply voltage. Therefore, no output is generated from the differential amplifier 23 that tends to increase the output DC voltage. The fact that no operation of increasing the DC output voltage occurs means that the duty of the switching element 15 is kept constant.

At this time, the AC power supply voltage has become 1/2, so the slope of the current flowing through the reactor 13 during the on period becomes 2fa,
The peak value of the current also becomes a 2f sound before t1. The duty is kept at 50% even after t1, but the on/off frequency changes. Voltage tV when reactor 13 is on
1 is 1/2 of +V2, and the voltage -V1 when off is -V
It is 1/2 of 2.・As with the conventional circuit, if the output voltage of the reference voltage forming circuit 24 in FIG. 1 is set to a fixed base voltage, the operation will be as shown in FIG. 3, and the DC output voltage will change regardless of changes in the AC voltage. An error control signal is generated from the differential amplifier 23 to keep the voltage constant, and the duty increases as shown in FIG. 3 (G) to compensate for the drop in the power supply voltage. When the load 41 fluctuates, the circuit shown in FIG. 1 also operates to maintain the output voltage constant as in the conventional circuit. Although the voltages at the output terminals 9 and 10 change due to switching of the power supply voltage, no problem occurs when a converter with a wide input range is connected as the load 41, which can tolerate changes in the input voltage. [Modifications] The present invention is not limited to the above-described embodiments, and, for example, the following modifications are possible.

(1) The reactor 13 may be connected to the AC input line of the rectifier circuit 8. (2> As shown in FIG. 4, a transformer primary winding 13a and a secondary winding 13b are provided in place of the reactor 13,
The switching element 15 may be connected in series with the primary winding 13a, and the energy stored in the transformer may be released through the secondary winding 13b. (3) As shown in FIG. 5, the switching element 15 is connected in series to the line 11, and the reactor 13 is connected to the line 11.
It may be connected between 1 and 12. {4} As shown in Figure 6, the transformer primary winding 1 as an inductance element
3a and the secondary winding 13b may be insulated and separated. (5) As shown in FIG. 7, in addition to the diode 14, a smoothing circuit consisting of a diode 51 and a reactor 52 may be provided at the output stage of the secondary winding 13b as an inductance element. Note that the voltage conversion circuit using the switching element 15 can be further modified in various ways. (6) If the output voltage is low, the voltage dividing circuit of the resistors 18 and 19 may be omitted and the voltage detection line 21 may be directly connected to the output terminal 9. (7) In order to obtain the sine wave (pulsating current) input to the multiplier 29 from the output line 11 of the rectifier circuit 8, the AC power supply terminal 1,
It may also be obtained by connecting an independent rectifier circuit to 2. (8) The circuit that forms control pulses for the switching element 15 based on the output of the differential amplifier 23 is not limited to that shown in FIG. 1, and can be modified in various ways. [Effects of the Invention] As is clear from the above, according to the present invention, the duty of the switching element, that is, the voltage conversion ratio, is kept constant despite changes in the AC power supply voltage. can be prevented.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing a DC power supply according to an embodiment of the present invention, Fig. 2 is a waveform diagram showing shapes A to G in Fig. 1, and Fig. 3 shows the operation of a conventional DC power supply. A waveform diagram shown corresponding to FIG. 2,

Claims (1)

[Scope of Claims] [1] An AC power terminal, a rectifier circuit connected to the AC power terminal, and a DC power source connected in series with an AC power line between the AC power terminal and the rectifier circuit, or a DC power source connected to the rectifier circuit. an inductance circuit element connected in parallel and/or series to the output line; and an inductance circuit element disposed on the output side of the rectifier circuit, which has an on/off operation with a cycle shorter than the cycle of the AC voltage of the AC power supply terminal. a switching element for controlling energy accumulation and release in the inductance circuit element; a smoothing capacitor provided on the output side of the switching element; and a voltage for detecting the DC output voltage smoothed by the smoothing capacitor. A DC power supply device comprising a detection circuit, and a control circuit that forms a control pulse for turning on and off the switching element based on the detected voltage obtained from the voltage detection circuit, and provides the control pulse to the switching element. , a reference voltage forming circuit for obtaining a DC voltage corresponding to the voltage of the AC power supply terminal or the rectifier circuit as a reference voltage; and a detection voltage obtained from the voltage detection circuit and a DC voltage obtained from the reference voltage forming circuit. a difference signal forming circuit for obtaining a voltage corresponding to a difference from a reference voltage; and a circuit forming a control pulse for the switching element based on an output of the difference signal forming circuit, the duty of the switching element being A DC power supply device comprising a control pulse forming circuit configured to follow changes in voltage at an AC power supply terminal and not change. [2] The control pulse forming circuit includes: a multiplier that multiplies the pulsating current obtained from the rectifying circuit or another rectifying circuit for detecting pulsating current by the difference signal obtained from the difference signal forming circuit; and the switching element. a current detector that detects a flowing current; a comparator that compares the output of the multiplier with the output of the current detector; and a comparator that is set after the reactor finishes releasing energy;
2. The DC power supply device according to claim 1, further comprising a flip-flop that is reset based on the output of the comparator and outputs a control pulse for the switching element.