JP4518965B2 - Switching power supply - Google Patents

Description

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

Conventional high power factor type switching power supplies (hereinafter referred to as “PFC”) are classified into three types according to the input ripple current waveform: discontinuous, critical, and continuous (refer to Patent Document 1 for criticality).
Japanese Patent Laid-Open No. 10-146049

  The continuous mode PFC has a small conduction loss due to a small effective current value of the switch element, and is suitable for a device having a relatively large output power. However, there is a problem that noise due to recovery of the diode is large. In addition, although a booster choke with a large L value is required, the input filter can be made small.

  Discontinuous and critical mode PFCs are suitable for devices with low output power, and do not generate noise due to diode recovery. Further, the boost choke can be made small, but a large input filter is required.

  In conventional discontinuous / critical / continuous mode PFCs, a large L value choke is required somewhere, and the size of the entire device cannot be made small and light.

  The present invention has been made in view of the above problems, and achieves downsizing and cost reduction of the input filter by increasing the frequency of the high-frequency ripple current flowing through the input filter and reducing the amplitude of the high-frequency component. A switching power supply device is provided.

  In order to solve the above-mentioned problem, the present invention connects a boost choke, a switch element, and a current detection resistor in series to a DC output of a full-wave rectifier connected to an AC power source through a high-frequency blocking filter, and the switch element is A rectifying and smoothing circuit comprising a rectifying diode, a current detecting element for detecting the current of the rectifying diode, and a smoothing capacitor configured to rectify the current of the boosting choke when off, and excitation of the boosting choke is reset A critical control mode high power factor type switching power supply controlled to start on later, and n outputs (n> = k) in parallel with the critical control mode high power factor type switching power supply at the output of the high-frequency blocking filter. In a switching power supply to which an equivalent critical control mode high power factor type switching power supply is connected, the kth critical control mode high power factor type The critical control mode high level located next to the kth critical control mode high power factor type switching power supply is developed in a loop by the current of the switching element of the switching power supply and the current of the rectifier diode of the rectifying and smoothing circuit. The power factor switching power supply is configured to control to shift off timing by adding / subtracting the current threshold value of the switching element of the power factor type switching power supply.

  The present invention also provides a boost choke, a switch element, and a current detection resistor connected in series to the DC output of a full-wave rectifier connected to an AC power source through a high-frequency blocking filter, and the booster is turned on when the switch element is off. A rectifying / smoothing circuit composed of a rectifying diode, a current detecting element for detecting the current of the rectifying diode, and a smoothing capacitor configured to rectify the current of the choke, and to be turned on after the excitation of the boost choke is reset. Critical power control mode high power factor type switching power supply, and n (n> = k) equivalent critical control modes in parallel with the critical control mode high power factor switching power supply at the DC output of the full-wave rectifier In a switching power supply device to which a high power factor type switching power supply is connected, the switching of the kth critical control mode high power factor type switching power supply is performed. A critical control mode high power factor type that is deployed next to the kth critical control mode high power factor type switching power supply in a loop shape by the current of the H element and the current of the rectifier diode of the rectifying and smoothing circuit. The present invention is characterized in that control is performed so as to shift off timing by adding / subtracting the current threshold value of the switching element of the switching power supply.

  According to the present invention, a plurality of critical control modes PFC are operated in parallel by shifting the operation timing of the switch elements, thereby increasing the frequency of the high-frequency ripple current flowing in the input filter and reducing the amplitude of the high-frequency component. Therefore, the choke with a large inductor value is not required, the entire apparatus can be reduced in size, the cost can be reduced, and a large output power and a low noise can be achieved at the same time.

FIG. 1 shows a circuit diagram in the best mode for carrying out the present invention. FIG. 2 shows a circuit diagram in the case where there is one critical control mode PFC according to the present invention.
The AC voltage of the AC power source 1 is full-wave rectified by the full-wave rectifier 3 via the high-frequency blocking filter 2. A boost choke 4, a switch element 8, and a current detection resistor 7 are connected in series to the direct current output of the full wave rectifier 3. A rectifier diode 9 is connected from the connection between the boost choke 4 and the switch element 8, and the rectifier diode 9, the current detection element 10, and the smoothing capacitor 11 are connected in series to form a rectifier smoothing circuit. The current of the booster choke 4 is detected when turned off.

  In the present embodiment, a critical control mode PFC 20 is provided, and this critical control mode PFC 20 is configured to be controlled so that the switch element 8 starts to turn on after the excitation of the boosting choke 4 is reset. Further, in the present embodiment, the switch element 8 is configured to be controlled by setting the off timing of the switch element 8 as a current threshold value that is proportional to the full-wave rectified voltage waveform.

  In the present embodiment, (n−1) equivalent critical control modes PFC 20 are connected to the output of the high-frequency rejection filter 2 in parallel with the critical control mode PFC 20. That is, in this embodiment, n critical control modes PFC 20 are provided.

Specifically, the equivalent critical control connected in parallel by the second unit is determined by the current IQ ₁ of the switch element 8 of the first critical control mode PFC 20 and the current Id ₁ of the rectifier diode 9 constituting the rectifying and smoothing circuit. The current IQ ₁ of the _first switch element 8 is subtracted by the second addition / subtraction operation circuit 16 from the output signal of the multiplication circuit 17 in the mode PFC 20, and the current Id ₁ of the first rectifier diode 9 is subtracted from the second signal. The addition / subtraction operation circuit 16 performs addition so as to control the off timing of the second switch element 8 to be shifted.

  Similarly, a plurality of critical control modes PFC 20 are controlled so as to shift off timing by adding / subtracting the current threshold value of the switch element 8 of the next equivalent critical control mode PFC 20 connected in parallel in the same manner as described above.

This is similarly configured up to the (n-1) th stage, that is, by the current of the switch element 8 of the critical control mode PFC 20 of the (n-1) th stage and the current of the rectifier diode 9 constituting the rectifying / smoothing circuit. The output signal of the multiplication circuit 17 of the switch element 8 of the equivalent critical control mode PFC 20 connected in parallel with the _n- th unit is the current IQ _n-1 of the (n-1) -th switch element 8 as the _n- th unit. The addition / subtraction operation circuit 16 performs subtraction, and the (n-1) _th current rectifier diode 9 current Idn _-1 is added by the nth addition / subtraction operation circuit 16, thereby shifting the off timing of the nth switch element 8. To control.

Subsequently, the current of the switch element 8 of the critical control mode PFC 20 connected in parallel with the nth unit and the current of the rectifier diode 9 constituting the rectifying and smoothing circuit are used to switch the switch element 8 of the first unit of critical control mode PFC 20. The current IQ _n of the _nth switch element 8 is subtracted from the output signal of the multiplication circuit 17 by the first addition / subtraction operation circuit 16, and the current Idn of the _nth rectifier diode 9 is subtracted from the first addition / subtraction operation circuit. Control is made so that the off timing is shifted by adding at 16. In other words, the current threshold value of the switch element 8 of the first critical control mode PFC 20 is determined by the current of the switch element 8 of the last critical control mode PFC 20 and the current of the rectifier diode 9 constituting the rectifying and smoothing circuit. It is configured to control so that the off timing is shifted by adding / subtracting.

  FIG. 3 shows input ripple current waveforms for 1, 2, and 3 units in the critical control mode PFC. FIG. 4 shows the input ripple current waveform and the voltage waveform of each part of the control circuit in the embodiment shown in FIG. Fig. 5 shows the input ripple current waveform and the voltage waveform of each part of the control circuit when two critical control modes PFC are operated in parallel, and Fig. 6 shows three critical control modes PFC operated in parallel. FIG. 7 shows the input ripple current waveform and the voltage waveform of each part of the control circuit when the four critical control modes PFC are operated in parallel.

  4 to 7, the plurality of critical control modes PFC are operated in parallel by shifting the operation timing of the switch elements, thereby increasing the frequency of the high-frequency ripple current flowing in the input filter and increasing the amplitude of the high-frequency component. By reducing, a choke with a large inductor value becomes unnecessary. This becomes more significant as the number of critical control mode PFCs increases. Based on the above, any number of critical control mode PFCs can be operated in parallel, the entire system can be downsized, the cost can be reduced, the output power can be increased, and the input filter can be reduced in size and cost. be able to.

FIG. 8 shows an embodiment in which only one full-wave rectifier 3 is used in the present invention.
The AC voltage of the AC power source 1 is full-wave rectified by the full-wave rectifier 3 via the high-frequency blocking filter 2. A critical control mode PFC 20 is connected to the direct current output of the full-wave rectifier 3 as in the embodiment shown in FIG.

  In the present embodiment, (n−1) equivalent critical control modes PFC 20 are connected to the output of the full-wave rectifier 3 in parallel with the critical control mode PFC 20. That is, in this embodiment, n critical control modes PFC 20 are provided.

  As in the embodiment shown in FIG. 1, a plurality of critical control modes PFC 20 are controlled so as to shift the off timing by adding / subtracting the current threshold value of the switch element 8 of the next equivalent critical control mode PFC 20 connected in parallel. To do.

  In the present embodiment, like the embodiment shown in FIG. 1, the operation waveforms as shown in FIGS. This makes it possible to increase the frequency of the high-frequency ripple current flowing in the input filter and reduce the amplitude of the high-frequency component by operating a plurality of critical control modes PFC in parallel by shifting the operation timing of the switch elements, thereby reducing the large L No value choke is required. This becomes more significant as the number of critical control mode PFCs increases. Based on the above, any number of critical control mode PFCs can be operated in parallel, the entire system can be downsized, the cost can be reduced, the output power can be increased, and the input filter can be reduced in size and cost. be able to.

FIG. 9 shows an embodiment in which the present invention is applied to an insulated critical mode PFC and two units are operated in parallel.
The AC voltage of the AC power source 1 is full-wave rectified by the full-wave rectifier 3 via the high-frequency blocking filter 2. The isolated critical control mode PFC is connected to the DC output of the full wave rectifier 3. In the present embodiment, another equivalent insulated critical control mode PFC is connected in parallel with the insulated critical control mode PFC to the output of the high-frequency blocking filter 2.

  As in the previous embodiment, the off timing is shifted by adding / subtracting the current threshold value of the switch element of the equivalent isolated critical control mode PFC in which two isolated critical control modes PFC are connected in parallel next to each other. Control.

  FIG. 10 shows an input ripple current waveform when two insulated critical control modes PFC are provided. As shown in this figure, the input ripple current waveform of this embodiment has a larger difference in the amplitude of the input ripple current waveform than the input ripple current waveform of the embodiment shown in FIG. Since the frequency of the current can be increased and the amplitude of the high frequency component can be reduced, a choke with a large inductor value is not required as in the above embodiment. This becomes more significant as the number of critical control mode PFCs increases. Based on the above, any number of critical control mode PFCs can be operated in parallel, the entire system can be downsized, the cost can be reduced, the output power can be increased, and the input filter can be reduced in size and cost. be able to.

FIG. 11 shows an embodiment in which the present invention is applied to a critical mode PFC using a non-insulated polarity reversing chopper and two units are operated in parallel.
Even in this case, the same control as in the above embodiment is performed, and the same effect as in the above embodiment is obtained.

FIG. 12 shows an embodiment in which the current of the rectifier diode 9 is calculated from the current of the boost choke winding 5 and the current of the switch element 8 in the present invention.
In this embodiment, a boost choke current detection resistor 22 is connected between the DC output of the full-wave rectifier 3 and the electrical load 12, and the boost choke current detection resistor 22 allows the current of the rectifier diode 9 to be boost choke. Calculation is performed from the current of the winding 5 and the current of the switch element 8.

  Other configurations are almost the same as those in the embodiment shown in FIG. 1, and the control means is almost the same as that in the embodiment shown in FIG.

  The present invention increases the frequency of the high-frequency ripple current flowing through the input filter and reduces the amplitude of the high-frequency component by operating a plurality of critical control modes PFC in parallel by shifting the operation timing of the switch elements. The L value choke is not required, the entire apparatus can be made small, the cost can be reduced, the output power can be increased in capacity, and the noise can be reduced at the same time.

In a high power factor type switching power supply, it is a circuit diagram which achieves size reduction and cost reduction of an input filter. It is a circuit diagram at the time of one critical control mode PFC. FIG. 2 shows the input ripple current waveform according to the method of the embodiment shown in FIG. 2, and the input ripple current waveform when there are two critical control modes PFC and three devices according to the method of the embodiment shown in FIG. It is a current waveform when the frequency is lower than the actual operation. 2 is an input ripple current waveform and a voltage waveform of each part of the control circuit according to the method of the embodiment shown in FIG. FIG. 1 shows the input ripple current waveform and the voltage waveform of each part of the control circuit when two critical control modes PFC are operated in parallel according to the method of the embodiment shown in FIG. FIG. 1 shows the input ripple current waveform and the voltage waveform of each part of the control circuit when three critical control modes PFC are operated in parallel according to the method of the embodiment shown in FIG. FIG. 1 shows the input ripple current waveform and the voltage waveform of each part of the control circuit when the critical control mode PFC is operated in parallel in the system of the embodiment shown in FIG. In this invention, it is an Example at the time of using the full wave rectifier 3 as one unit. In the present invention, the present invention is applied to an insulated critical mode PFC and is an embodiment in which two units are operated in parallel. 9 is an input ripple current waveform according to the method of the embodiment shown in FIG. In the present invention, the present invention is applied to a critical mode PFC using a non-insulated polarity reversal chopper, and two units are operated in parallel. In this embodiment, the current of the rectifier diode 9 is calculated from the current of the boost choke winding 5 and the current of the switch element 8.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2 High frequency block filter 3 Full wave rectifier 4 Boost choke 5 Boost choke winding 6 Excitation reset detection winding 7 Current detection resistor 8 Switch element 9 Rectifier diode 10 Current detection element 11 Smoothing capacitor 12 Electrical load 13 NOT logic circuit 14 RS latch circuit 15 Comparator 16 Addition / subtraction operation circuit 17 Multiplication circuit 18 Error amplifier 19 Reference voltage 20 Critical control mode PFC
21 Common mode choke coil 22 Boost choke current detection resistor

Claims (2)

A boost choke, a switch element, and a current detection resistor are connected in series to the DC output of a full-wave rectifier connected to an AC power source through a high-frequency blocking filter, and the current of the boost choke is rectified when the switch element is off. A rectifying / smoothing circuit comprising a rectifying diode, a current detecting element for detecting the current of the rectifying diode and a smoothing capacitor, and a critical control controlled so that the boost choke is turned on after the excitation is reset. Mode high power factor type switching power supply, and n (n> = k) equivalent critical control mode high power factor type switching power supplies in parallel with the critical control mode high power factor type switching power supply at the output of the high-frequency blocking filter In the switching power supply to which is connected, the current of the switching element of the kth critical control mode high power factor type switching power supply The switching element of the critical control mode high power factor type switching power supply that is deployed in a loop by the current of the rectifying diode of the rectifying and smoothing circuit and is positioned next to the kth critical control mode high power factor type switching power supply A switching power supply device configured to control to shift off timing by adding / subtracting the current threshold value. A boost choke, a switch element, and a current detection resistor are connected in series to the DC output of a full-wave rectifier connected to an AC power source through a high-frequency blocking filter, and the current of the boost choke is rectified when the switch element is off. A rectifying / smoothing circuit comprising a rectifying diode, a current detecting element for detecting the current of the rectifying diode, and a smoothing capacitor, and critical control controlled so that the boost choke is turned on after the excitation is reset. Mode high power factor type switching power supply, and n (n> = k) equivalent critical control mode high power factor type switching power supplies in parallel with the critical control mode high power factor type switching power supply in the DC output of the full-wave rectifier Is connected to the switching element current of the kth critical control mode high power factor type switching power supply. The switching element of the critical control mode high power factor type switching power supply located next to the kth critical control mode high power factor type switching power supply is developed in a loop by the current of the rectifying diode of the rectifying and smoothing circuit. A switching power supply device configured to control to shift off timing by adding / subtracting a current threshold.

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