JP2008125313A - Switching power supply - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the size and the cost of an input filter in a high power factor switching power supply (PFC), and to reduce a loss of the power supply caused by a semiconductor. <P>SOLUTION: The switching power supply achieves high efficiency by employing a two-transistor critical mode PFC interleave system in place of a single transistor critical mode PFC interleave system thereby reducing a loss of a VF by a diode bridge. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an improvement of a high power factor type switching power supply (hereinafter referred to as PFC) using an AC power supply as an input.

  As a conventional PFC, there are circuit systems as shown in FIGS.

FIG. 4 is a one-stone current critical mode PFC, and FIG. 6 is a parallel connection of a plurality of PFCs of FIG. 4 to uniformly control the phase difference of the ripple current of each boost choke. As a result, the frequency of the high-frequency ripple current flowing through the input filter can be increased and the amplitude of the high-frequency component can be reduced, and the input filter can be reduced in size and cost. (See Patent Document 1)
JP 2006-204008 A

  However, in order to realize high efficiency with a large output capacity, there is a problem that the loss generated by two VFs due to the diode bridge is large in these one-stone circuit systems.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a switching power supply device that can achieve a reduction in size and cost of an input filter and a reduction in loss of a device generated by a semiconductor. It is.

  In order to achieve the above-described object, the present invention is a converter that receives an AC power supply and outputs a DC voltage. The DC voltage output has positive and negative electrodes, a smoothing capacitor, two series switch element arms, and two. A series rectifier diode is connected, a current detecting element and a boost choke are connected in series to the AC power source via a high-frequency blocking filter, and one end of the boost choke and one end of the high-frequency blocking filter are connected to the intermediate point of the arm. A critical control mode high power factor type switching power supply connected to the intermediate point of the rectifier diode and controlled to start after the boost choke excitation is reset is connected in series with a current detection element and two boost chokes. A plurality of booster operation circuits composed of switch element arms are connected to the output of the high-frequency block filter and the positive and negative electrodes of the DC voltage output. In the switching power supply unit, the control of shifting the off timing by subtracting the current of the above arm from the current threshold value for controlling another arm is configured in a loop, and the phase difference of the ripple current of all boosting chokes is equally controlled It is characterized by doing.

  According to the present invention, it is possible to reduce the size and cost of the input filter and reduce the loss caused by the semiconductor.

  FIG. 1 shows a circuit diagram for carrying out the present invention.

  The converter has a configuration in which an AC power supply is input and a DC voltage is output. A smoothing capacitor 7, two series switch arms 5 and two series rectifier diodes 6 are connected to the positive and negative electrodes of the DC voltage output. The AC power source 1 is connected in series to the current detection element 3 and the boost choke 4 via the high-frequency blocking filter 2. One end of the boosting choke 4 and one end of the high-pass blocking filter 2 are connected to the intermediate point of the arm and the intermediate point of the rectifier diode 6. An electrical load 8 is connected to the smoothing capacitor 7 connected to the DC output.

  The DC output voltage is amplified and integrated by the error amplifier 9 with respect to the voltage error from the reference voltage Vref18, and the multiplier 10 multiplies the input voltage by the full-wave rectified signal to output a current reference signal Iref. The comparator 12 compares the Iref and the full-wave rectified signal of the input current detected by the current detection element 3 to obtain a reset signal for the RS latch circuit 14.

  The turn-on timing is detected by the voltage detection winding of the boost choke 4. By detecting the polarity of the voltage polarity of the AC power supply 1 and detecting the voltage of the voltage detection winding separately for each positive and negative period, the reset of excitation of the boost choke 4 is detected and used as a set signal for the RS latch circuit 14 . The output of the RS latch circuit 14 turns on / off the switch element 5 on the lower side of the arm while the voltage of the AC power supply 1 is positive, and turns on / off the switch element 5 on the upper side of the arm during the negative period.

  The current detection element 3 is connected to each switch element 5, and the detected current signal is added by the addition circuit 23. Further, a booster circuit comprising a circuit composed of another pair of current detecting elements, a booster choke and two series switch element arms, and a control circuit for controlling it in a critical mode, is connected to the output of the high-frequency blocking filter and the direct current. Connect multiple units to the positive and negative electrodes of the voltage output.

  Control for shifting the off timing is performed by subtracting the current of the arm by the addition / subtraction circuit 24 from the current reference signal Iref which is a current threshold value for controlling another set of arms. By configuring this control in a loop shape, the phase difference of the ripple currents of all the boost chokes can be controlled uniformly.

  The present invention is characterized in that a plurality of booster circuits can be connected. FIG. 2 shows an embodiment of the present invention when there are two sets of booster circuits having the minimum configuration. FIG. 3 shows waveforms at various parts in FIG.

  As shown in FIG. 3, the sum of Irip (1) and Irip (2) becomes Iripple, and the phase difference of the ripple current of the boost choke is controlled uniformly. In the example of two booster circuits, the frequency of the high-frequency ripple component of Iripple is doubled. Therefore, the effect of the present invention can be increased as the number of booster circuit sets is increased.

It is a circuit diagram which shows the switching power supply device which concerns on embodiment of this invention. FIG. 10 is a circuit diagram of a switching power supply apparatus according to another embodiment of the present invention when there are two booster circuits. It is a figure which shows the waveform of each part of FIG. FIG. 6 is a circuit diagram of a conventional one-crystal current critical mode PFC. FIG. 5 is a diagram showing a current waveform of a boost choke in the current critical mode PFC of FIG. 4. It is a circuit diagram of another conventional example (patent document 1). It is a figure which shows the electric current waveform of the pressure | voltage rise choke of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2 High frequency block filter 3 Current detection element 4 Boost choke 5 Switch element 6 Rectifier diode 7 Smoothing capacitor 8 Electric load 9 Error amplifier 10 Multiplication circuit 11 Absolute value calculation circuit 12 Comparator 13 NOT logic circuit 14 RS latch circuit 15 OR logic circuit 16 AND logic circuit 17 differential amplifier 18 reference voltage Vref
19 Timer circuit 20 Delay delay circuit 21 Vth voltage source 22 for setting the threshold value −Vth voltage source 23 for setting the threshold value 23 Adder circuit 24 Addition / subtraction circuit 25 Bridge diode 26 Current detection resistor 27 Critical control mode PFC

Claims (1)

A converter that takes an AC power supply as an input and outputs a DC voltage, and a high-frequency blocking filter comprising a smoothing capacitor, two series switch element arms, and two series rectifier diodes connected to the positive and negative electrodes of the DC voltage output. A current detecting element and a boosting choke are connected in series to the AC power source via the power supply, and one end of the boosting choke and one end of the high-pass blocking filter are connected to the midpoint of the arm and the midpoint of the rectifier diode, A critical control mode high power factor type switching power supply controlled to start on after the excitation of the choke is reset performs a boosting operation constituted by an arm of a current detection element, a boosting choke, and two switching elements in series. In a switching power supply device in which a plurality of circuits are connected to the output of the high-frequency blocking filter and the positive and negative electrodes of the DC voltage output,
A control for shifting the off timing by subtracting the current of the arm from a current threshold value for controlling another arm is configured in a loop shape, and the phase difference of the ripple currents of all boosting chokes is uniformly controlled. Switching power supply.

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