Interleaved zero current switching in a power factor correction boost converter
First Claim
1. A controller for a power factor correction boost converter comprising:
- a. first means for controlling charging of a first inductor with energy from an alternating-current power supply and for controlling discharging of the first inductor into an output capacitor wherein the first means operates in accordance with a first clock signal;
b. second means for controlling charging of a second inductor with energy from the power supply and for controlling discharging of the second inductor into the output capacitor wherein the second means operates in accordance with a second clock signal and wherein the second means is coupled to the first means; and
c. means for forming a synchronizing output signal for synchronizing operation of a pulse width modulation converter with the power factor correction boost converter wherein the synchronizing output signal is synchronous with at least one of the first clock signal and the second clock signal.
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Abstract
A method and apparatus for interleaving switching of multiple transistor switches in a power factor correction (PFC) boost converter and for timing the switching to occur when a current through a freewheeling diode corresponding to each switch is at a minimum level. The converter draws input current from an alternating current power supply for forming a regulated output voltage. A controller senses an input current and an output voltage across an output capacitor for controlling switching to regulate the output voltage and to ensure that the input current is substantially in phase with an input voltage. Current through a first inductor associated with a first switch is allowed to fall substantially to zero upon discharging the first inductor prior to re-charging the first inductor. Charging of a second inductor associated with a second switch, however, is initiated prior to completion of discharging the first inductor. Similarly, current through the second inductor is allowed to fall substantially to zero prior to re-charging the second inductor. An advantage is that from the perspective of the power supply, the converter operates in continuous conduction mode, while from the perspective of each of the switches, the converter operates in discontinuous conduction mode. The invention reduces power dissipated in the switches, increasing reliability and allowing higher frequency operation. In accordance with another aspect of the invention, a synchronizing signal is generated by the PFC converter for synchronizing operation of a second converter, such as a pulse-width modulation converter, with the PFC converter.
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Citations
48 Claims
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1. A controller for a power factor correction boost converter comprising:
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a. first means for controlling charging of a first inductor with energy from an alternating-current power supply and for controlling discharging of the first inductor into an output capacitor wherein the first means operates in accordance with a first clock signal; b. second means for controlling charging of a second inductor with energy from the power supply and for controlling discharging of the second inductor into the output capacitor wherein the second means operates in accordance with a second clock signal and wherein the second means is coupled to the first means; and c. means for forming a synchronizing output signal for synchronizing operation of a pulse width modulation converter with the power factor correction boost converter wherein the synchronizing output signal is synchronous with at least one of the first clock signal and the second clock signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A power factor correction boost converter comprising:
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a. a first energy storage element for receiving energy from an alternating-current power supply; b. a first switch coupled to the first energy storage element wherein the first switch is selectively conditioned open or closed and wherein when the first switch is closed, energy is transferred from the power supply to the first energy storage element; c. a second energy storage element for receiving energy from the power supply;
p1 d. a second switch coupled to the second energy storage element wherein the second switch is selectively conditioned open or closed and wherein when the second switch is closed, energy is transferred from the power supply to the second energy storage element; ande. a third energy storage element coupled to the first switch and to the second switch, wherein when the first switch is opened, energy is transferred from the first energy storage element to the third energy storage element and wherein when the second switch is open, energy is transferred from the second energy storage element to the third energy storage element; and f. a controller coupled to the first switch and to the second switch wherein the controller senses a current provided by the power supply for controlling switching. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A controller for a power factor correction boost converter comprising:
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a. first means for controlling charging of a first inductor with energy from an alternating-current power supply and for controlling discharging of the first inductor into an output capacitor; and b. second means for controlling charging of a second inductor with energy from the power supply and for controlling discharging of the second inductor into the output capacitor wherein the first means and the second means are responsive to a sensing signal representative of a level of current drawn by the power factor correction boost converter. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34)
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35. A controller for power factor correction boost converter comprising:
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a. first means for controlling charging of a first inductor with energy from an alternating-current power supply and for controlling discharging of the first inductor into an output capacitor wherein the first means is responsive to a first ramp signal and wherein a rate at which the first ramp signal rises is representative of a voltage across the capacitor; and b. second means for controlling charging of a second inductor with energy from the power supply and for controlling discharging of the second inductor into the output capacitor wherein the second means is responsive to a second ramp signal and wherein a rate at which the second ramp signal rises is representative of a voltage across the output capacitor. - View Dependent Claims (36, 37, 38, 39, 40, 41, 42, 43)
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44. A method of performing power factor correction in a boost converter, the method comprising steps of:
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a. charging a first inductor with energy from an alternating-current power supply; b. discharging the first inductor into an output capacitor; c. forming a first ramp signal wherein a rate at which the first ramp signal rises is representative of a voltage across the output capacitor; d. charging a second inductor with energy from the power supply wherein the step of charging the second inductor is initiated prior to completion of the step of discharging the first inductor; e. forming a second ramp signal wherein a rate at which the second ramp signal rises is representative of a voltage across the output capacitor; and f. discharging the second inductor into the output capacitor. - View Dependent Claims (45, 46)
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47. A method of performing power factor correction in a boost converter, the method comprising steps of:
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a. charging a first inductor with energy from an alternating-current power supply; b. discharging the first inductor into an output capacitor; c. charging a second inductor with energy from the power supply wherein the step of charging the second inductor is initiated prior to completion of the step of discharging the first inductor; d. discharging the second inductor into the output capacitor; and e. sensing a voltage across the output capacitor and a combined current drawn from the power supply through the first and second inductors for controlling timing for performing the steps a.-d.. - View Dependent Claims (48)
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Specification