Unity power factor switching regulator
First Claim
1. A single or multiphase chopper for operating a load from single or multiphase line energy with unity power factor, comprising a power section for converting single or multiphase alternating current line energy into direct current load energy including a rectifier, and for each chopper phase at least one inductor and one chopper switch for presenting said load with direct current, and duty cycle control mean for each chopper switch to control the average inductor current over each period of the chopper switch, and a sensing and control section including means for sensing at least one load parameter, means for producing a current command signal as a function of said parameter, means for sensing average current through every inductor included, means for producing a feedback signal as a function of said current command signal and the average rectifier voltage output over each period of every chopper switch included, and means for comparing said feedback signal with said sensed average current to produce, in response to a difference, a control signal applied to said duty cycle control means, whereby the instantaneous line current is maintained proportionate to the instantaneous line voltage, thus achieving a unity power factor.
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Abstract
A single or multiphase boost chopper regulator operating with unity power factor, for use such as to charge a battery is comprised of a power section for converting single or multiphase line energy into recharge energy including a rectifier (10), one inductor (L1) and one chopper (Q1) for each chopper phase for presenting a load (battery) with a current output, and duty cycle control means (16) for each chopper to control the average inductor current over each period of the chopper, and a sensing and control section including means (20) for sensing at least one load parameter, means (22) for producing a current command signal as a function of said parameter, means (26) for producing a feedback signal as a function of said current command signal and the average rectifier voltage output over each period of the chopper, means (28) for sensing current through said inductor, means (18) for comparing said feedback signal with said sensed current to produce, in response to a difference, a control signal applied to the duty cycle control means, whereby the average inductor current is proportionate to the average rectifier voltage output over each period of the chopper, and instantaneous line current is thereby maintained proportionate to the instantaneous line voltage, thus achieving a unity power factor. The boost chopper is comprised of a plurality of converters connected in parallel and operated in staggered phase. For optimal harmonic suppression, the duty cycles of the switching converters are evenly spaced, and by negative coupling between pairs 180° out-of-phase, peak currents through the switches can be reduced while reducing the inductor size and mass.
236 Citations
17 Claims
- 1. A single or multiphase chopper for operating a load from single or multiphase line energy with unity power factor, comprising a power section for converting single or multiphase alternating current line energy into direct current load energy including a rectifier, and for each chopper phase at least one inductor and one chopper switch for presenting said load with direct current, and duty cycle control mean for each chopper switch to control the average inductor current over each period of the chopper switch, and a sensing and control section including means for sensing at least one load parameter, means for producing a current command signal as a function of said parameter, means for sensing average current through every inductor included, means for producing a feedback signal as a function of said current command signal and the average rectifier voltage output over each period of every chopper switch included, and means for comparing said feedback signal with said sensed average current to produce, in response to a difference, a control signal applied to said duty cycle control means, whereby the instantaneous line current is maintained proportionate to the instantaneous line voltage, thus achieving a unity power factor.
- 7. In a system for charging a battery, said system having at least one converter comprised of a duty cycle controlled chopper switch and inductor for translating energy from an alternating current line to a direct current into said battery, said system also having means for rectifying said alternating current into said converter, an improvement for operation of said system with a unity power factor consisting of means for feedback control of the duty cycle for the chopper switch such that the average inductor current over each period of the chopper switch is proportionate to the average voltage output of said rectifying means during the same chopper switch period, whereby instantaneous line current is maintained proportionate to the instantaneous line voltage for unity power factor, said feedback control means being comprised of means for sensing at least one parameter of said battery, means responsive to said sensing means for producing a charge current command signal, means for producing a signal that is the product of the average voltage of said line during a chopper switch period and said current command signal, means for sensing current through said inductor, means for comparing said inductor current with said product signal, and means for controlling the duty cycle of said chopper in response to the difference between said line voltage and said inductor current.
- 13. In a system for converting ac or dc energy to dc energy using a plurality of duty cycle controlled converters connected in parallel, and cyclically operating said converters in phase staggered sequence such that the duty cycles of the converters are evenly spaced apart, each converter being comprised of a chopper switch and an inductor, an improvement consisting of negative coupling of said inductor in each converter to an inductor in another converter selected to cancel odd current harmonics in the two inductors so coupled, thereby to reduce ripple in the dc output of said system.
Specification