JPH02307365A - Power-supply device - Google Patents

Abstract

PURPOSE:To improve a power-factor by connecting a full-wave rectification circuit and a step-up/step-down type chopper circuit dependently on each other. CONSTITUTION:A DC power-supply device is composed of the full-wave rectifica tion circuits D1-D4 of a commercial frequency AC power source, a step-up/ step-down type chopper circuit with first-second chopper switching elements Q1-Q2, a chopper inductor L1, and the like, a chopper controlling circuit CHC for controlling the ON/OFF-time of said switching elements Q, and the like. Then, input current is controlled to come to a value in proportion to input voltage, and the generation of reactive power and harmonic current can be suppressed.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a DC power supply device that converts power input from a commercial frequency AC power source and supplies DC power, and can be used in general electrical and electronic equipment. .

Problems to be Solved by the Prior Art and the Invention Conventional DC power supplies generally have a rectifier circuit and a smoothing circuit using passive elements (the smoothing circuit using passive elements has a capacitor input as shown in Figure 3). The input current waveform is pulse-shaped or square wave-like, and unlike the input voltage waveform which is close to a normal sine wave, it has a poor power factor and high harmonics. There was a problem in that wave currents caused adverse effects such as induced noise on other devices connected to the AC power supply or on nearby communication lines.

Furthermore, the smoothing circuit using active elements shown in Fig. 5 has conventionally been configured with a step-up chopper circuit, and cannot be applied when attempting to supply DC power at a voltage lower than the voltage of the input commercial frequency AC power supply. Ta.

Means for Solving the Problems The present invention provides a power supply device that solves the above problems. a first switching element having one end connected to the other terminal with one terminal of the first capacitor as a common line; and one end connected to the other end of the first switching element. a first rectifying element connected between a common line between the first switching element and the connection point of the inductor, and a second rectifying element having one end connected to the other end of the inductor. , a second switching element connected between a common line between the inductor and the second rectifying element, and a second capacitor connected between the second rectifying element and the common line. The power supply device has both ends of the second capacitor as DC output terminals, and turns on and off the first and second switching elements almost simultaneously at a frequency that is six times or more higher than the frequency of the input AC power. The ON and OFF times of the first and second switching elements are controlled so that the voltage waveform of the rectified output terminal of the full-wave rectifier circuit and the short-time average value waveform of the current waveform of the first switching element are approximately proportional to each other. This is a power supply device characterized by the following. Further, in the above power supply device, the proportionality coefficient between the voltage waveform of the rectified output terminal and the short-time average value of the current waveform of the first switching element is made variable by a variable resistor, a switch, or the like. . Furthermore, in the above power supply device, the proportionality coefficient between the voltage waveform of the rectified output terminal and the short-time average value of the current waveform of the first switching element is made variable by an electric signal from outside or inside the power supply device. It is something.

Function The present invention connects a full-wave rectifier circuit and a buck-boost type chopper circuit in cascade to control the input current to a value approximately proportional to the input voltage. This realizes an ideal power supply device that maintains the power factor of the input current at a value close to 1 for the combination and suppresses the generation of reactive power and harmonic current.

Example The present invention will be explained below with reference to the embodiment shown in FIG.

FIG. 1 is a circuit diagram of the main parts of the power supply device of the present invention, and its operation will be explained. C5 is a capacitor with a capacitance value that has a smoothing effect on the switching frequency of the buck-boost type chopper circuit and has a high impedance for the commercial frequency of AC input. The output voltage of the rectifier circuit consisting of %DT~04 ■The waveform of 1 becomes a pulsating waveform as shown in Fig. 2(a), and chopper switching elements Q, , and C2 are simultaneously turned on.
, OFF is repeated, and the energy temporarily stored in the chopper inductor L is boosted or stepped down and sent to the output side. At this time, the chopper control circuit CHC causes the chopper switching current is flowing through the chopper switching elements Q4 and C2 to become the second By controlling the chopper switching elements Q5 and C2 to be turned off when the value of the envelope IJ2 shown in FIG. , has the waveform shown in FIG. 2 (1)). Output voltage waveform of the rectifier circuit in Figures 2(a) and 2(b)■
1 and the output current waveform i are almost proportional,
An ideal AC input current with a power factor close to 1 is achieved.

Note that in the figure, 2 indicates the output voltage waveform.

In the control circuit CHC, the output voltage setting value ref is given from the outside, and the output voltage is monitored by resistors R3 and R4, and the envelope value of the switching current is to adjust the output voltage.

Further, the output current is monitored by the resistor R6, and the circuit operation is stopped in the event of an abnormality such as load overload or overload.

The resistors R, , R2 are voltage dividing resistors that monitor the output voltage (2) of the rectifier circuit, and the resistor R5 is a resistor that monitors the switching current i5.

If the chopper switching current envelope value 1j2 is changed in proportion to the rectifier circuit output voltage waveform v1 when the ON/OFF repetition period of the chopper switching element is constant, the rectifier circuit output current 11 will be proportional to It can be shaped. In this case, there is a period in which the current in the chopper inductor L becomes zero.

When the chopper switching element is turned on again at the same time that the current in the chopper inductor L1 becomes zero, the chopper switching current envelope value 11 may be set to the following value. When the input voltage waveform is a sine wave, the rectifier circuit output voltage waveform is expressed as V, = V, 0 sin θ, where θ is the phase angle from the zero cross.

Also, let the period during which the chopper switching element is conductive at this time be tl, and the peak current of the chopper inductor L at this time be IL, and then the chopper switching element is rendered non-conductive and the current of the chopper inductor L1 becomes 0 through the chopper diodes 05 and D6. The waiting period for
2, when the output voltage of the buck-boost type chopper circuit is v2, it is approximately.

Duty ratio of chopper switching element: 1, /1
．． +12 becomes + +t2 1 +V+ /V2.

The chopper switching current i5 is smoothed by the capacitor C2, and the average value becomes the output current i of the rectifier circuit, so the output current waveform of the rectifier circuit is 1,=l. sin θ.In order to ideally form the chopper switching current envelope value 11, it is recommended that the chopper switching current envelope value 11 be the value obtained by
By providing an analog or digital arithmetic circuit, turning off the chopper switching element when the current reaches this value, and turning on the chopper switching element again when the current flowing through the chopper inductor L1 becomes zero, the ideal input current can be obtained. Waveforms can be obtained.

Effects of the Invention As described above, the present invention connects a full-wave rectifier circuit and a buck-boost type chopper circuit in cascade to control the input current to a value approximately proportional to the input voltage. It is industrially useful because it has little induced noise and can be applied to power supplies for electronic and electrical equipment.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of the main part of the embodiment of the present invention, Fig. 2 is a waveform characteristic diagram in a rectifier circuit, where (a) is a voltage one-hour characteristic diagram, (b) is a current one-hour characteristic diagram, and 4 is a smoothing circuit diagram of a conventional DC current device, and FIG. 5 is a smoothing circuit diagram using a conventional active element. C5, C2: Capacitor R,, R2, R3, R4, R5, Rs: Resistor Q,, Q
2 Switching element: Chopper inductor C) Ic: Chopper control circuit Dl, D2, D3, D4, D5, D6: Diode

Claims (1)

[Claims] A first capacitor connected between a full-wave rectifier circuit that inputs AC power and a rectified output terminal of the full-wave rectifier circuit, one terminal of the first capacitor being a common line, and one end connected to the other terminal. an inductor having one end connected to the other end of the first switching element, and a first switching element connected between a common line between the first switching element and the connection point of the inductor. 1 rectifying element;
a second rectifying element whose one end is connected to the other end of the inductor; a second switching element connected between a common line between a connection point of the inductor and the second rectifying element;
A power supply device that has a second capacitor connected between the rectifying element and the common line, and has both ends of the second capacitor as DC output terminals, and has a frequency that is 6 times or more the frequency of the input AC power. Then, the first and second switching elements are turned on and off almost simultaneously, and the voltage waveform of the rectified output terminal of the full-wave rectifier circuit and the short-time average value waveform of the current waveform of the first switching element are approximately proportional to each other. A power supply device characterized in that the ON and OFF times of the first and second switching elements are controlled so as to control the ON and OFF times of the first and second switching elements.