Electric power supply circuit and PAM control method for the same
First Claim
1. An electric power supply circuit comprising:
- a rectifier circuit which is connected to an alternating current power source and which rectifies alternating current power;
a smoothing circuit which has two capacitors serially connected to each other and which is connected to an output side of the rectifier circuit;
a switching element which, when turned into an ON state, connects the alternating current power source and a midpoint between the two capacitors and which causes a short circuit of an output power of the rectifier circuit; and
a PAM control section which outputs a pulse signal for switching the switching element, at a predetermined timing based on a zero-cross point of an input voltage of the rectifier circuit, whereinthe PAM control section includes;
a phase difference detection section which detects, based on an amount of charge in the two capacitors, a shift between an output phase of the pulse signal and a phase of a pulse signal that makes an input current of the rectifier circuit have a sine waveform; and
a phase correction section which shifts the output phase of the pulse signal in a lead direction or a lag direction so that the phase shift detected by the phase difference detection section is removed.
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Accused Products
Abstract
An increase in a ripple voltage of a capacitor in a smoothing circuit is prevented to achieve a compact capacitor and cost reduction for capacitors in an electric power supply circuit which performs PAM control using a switching element. An electric power supply circuit includes a bridge circuit for rectifying alternating current power, a smoothing circuit which has two capacitors serially connected to each other, and a PAM control section for turning a switching element on and off at a predetermined timing. The PAM control section includes a phase difference detection section which detects a phase shift of a PAM waveform based on a change in a voltage difference between the two capacitors, and a phase correction section which corrects the phase of the PAM waveform so that an input current has a sine waveform.
6 Citations
7 Claims
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1. An electric power supply circuit comprising:
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a rectifier circuit which is connected to an alternating current power source and which rectifies alternating current power; a smoothing circuit which has two capacitors serially connected to each other and which is connected to an output side of the rectifier circuit; a switching element which, when turned into an ON state, connects the alternating current power source and a midpoint between the two capacitors and which causes a short circuit of an output power of the rectifier circuit; and a PAM control section which outputs a pulse signal for switching the switching element, at a predetermined timing based on a zero-cross point of an input voltage of the rectifier circuit, wherein the PAM control section includes; a phase difference detection section which detects, based on an amount of charge in the two capacitors, a shift between an output phase of the pulse signal and a phase of a pulse signal that makes an input current of the rectifier circuit have a sine waveform; and a phase correction section which shifts the output phase of the pulse signal in a lead direction or a lag direction so that the phase shift detected by the phase difference detection section is removed. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A PAM control method for an electric power supply circuit comprising:
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a rectifier circuit which is connected to an alternating current power source and which rectifies alternating current power; a smoothing circuit which is connected to an output side of the rectifier circuit and which has two capacitors serially connected to each other, a switching element which, when turned into an ON state, connects the alternating current power source and a midpoint between the two capacitors and which causes a short circuit of an output power of the rectifier circuit; and a PAM control section which outputs a pulse signal for switching the switching element at a predetermined timing based on a zero-cross point of an input voltage of the rectifier circuit, wherein the PAM control section detects a voltage difference between the two capacitors, and shifts an output phase of the pulse signal in a lead direction or a lag direction in stages according to the voltage difference between the two capacitors so that the output phase of the pulse signal is a predetermined phase that makes an input current of the rectifier circuit have a sine waveform.
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Specification