Power Factor Improvement Circuit
A power factor improvement and circuit technology, which is applied in the field of power factor improvement circuits, can solve problems such as inability to improve power factor converters, and achieve the effect of improving efficiency
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Embodiment 1
[0024] figure 1 It is a circuit diagram of the power factor improvement circuit of Embodiment 1 of this invention. exist figure 1 In the power factor improvement circuit of Embodiment 1 shown, the filter 2 removes noise and the like included in the AC voltage from the AC power supply 1 . The full-wave rectification circuit DB rectifies the AC voltage from the filter 2 and outputs it to both ends of the capacitor C1.
[0025] A series circuit of a reactor L, a switching element Q1, and a current detection resistor R1 is connected to both ends of the capacitor C1. The switching element Q1 is formed of a MOSFET, and a series circuit of a diode D1 and a capacitor C2 is connected between the drain and the source of the switching element Q1.
[0026] A series circuit of a resistor R2 and a resistor R3 is connected to both ends of the capacitor C2. The reactor L is composed of a main winding La and an auxiliary winding Lb that are electromagnetically coupled to each other. One en...
Embodiment 2
[0034] The PFC control unit 10 of Embodiment 2 performs the following steps when the load is light Figure 4 action shown. That is, in the case of Figure 4 When the input voltage Vin shown in (a) is low, the PFC control unit 10 is Figure 4 As shown in (b), the switching element Q1 is controlled four times, and when the input voltage Vin is high, the PFC control unit 10 is as follows: Figure 4 As shown in (c), one jump control is performed on the switching element Q1.
Embodiment 3
[0036] Figure 5 It is a detailed circuit diagram of the PFC control part in the heavy load of the power factor improvement circuit of Example 3 of this invention. The power factor improvement circuit of Embodiment 3 is image 3 A specific example of the PFC control unit 10 is shown.
[0037] Figure 5 The PFC control section 10a shown has: current sources I1, I2, capacitors C11, C12, flip-flop circuits FF1, FF2, comparators CP1, CP2, transistors Q11, Q12, "AND" circuits AND 1, AND 2, ZCD( Zero-cross current detector) 12, delay circuit 13, one-shot circuit 14, counter 15, jump circuit 16, falling edge one-shot circuit 17, operational amplifier OTA1, and reference voltage Vr.
[0038]The non-inverting terminal of the operational amplifier OTA1 is connected to the reference voltage Vr, and the inverting terminal is connected to the FB terminal. The operational amplifier OTA1 and the reference voltage Vr form an error amplifier of the output voltage. In addition, the capacito...
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