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US 5,493,487 AGranted
Electronic switching circuit
AssigneePerformance Controls, Inc.
InventorsEric C. Close, Jerry K. Goff
Life of this patent
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AssigneePerformance Controls, Inc.
InventorsEric C. Close, Jerry K. Goff
Estimating the term…
A pulse-width modulated (PWM) circuit provides current through a load by opening and closing main electronic switches which connect the load to a power supply. Each main electronic switch connects with an auxiliary switch, connected in series with a diode, the auxiliary switch and diode being called "recovery paths". The recovery paths provide a path between the load and the associated main switch, on one side, and the power supply on the other. A first train of pulses, derived from a command signal, drives the main switches, and a second train of pulses, derived from the first pulse train, controls the switches in the recovery paths. One arranges the second train such that the recovery paths carry current only while the main switches change from on to off, or from off to on. In this way, the recovery paths carry part of the current that would otherwise flow transiently through the main switches, due to the inherent inefficiencies in semiconductor switching. Therefore, the present invention allows the main switches to increase in efficiency as compared with circuits of the prior art. In an alternative embodiment, the recovery path includes the load but excludes the power supply, so that current can flow only transiently through the recovery path. The latter embodiment requires fewer switches than the previous embodiment, and is therefore less costly.
In an electronic switching circuit for providing current through a load, the circuit comprising four main electronic switches connected between a power supply and the load, a first pair of main switches being controlled by a drive circuit operated by a first pulse-width modulated (PWM) signal derived from a command signal, the second pair of main switches being controlled by a drive circuit operated by a second PWM signal which is derived from the complement of the first PWM signal,
In a method of providing current through a load, the method comprising the steps of generating a pulse-width modulated (PWM) signal from a command signal, and applying said PWM signal to a drive circuit of at least one main electronic switch connected between the load and a power supply, the improvement which comprises the step of diverting the current flowing through said main electronic switch into an auxiliary circuit path, the diversion being done either when the main switch is being turned on or off, the auxiliary circuit path including the load and excluding the power supply, the auxiliary switch being independent of the drive circuit.
Apparatus for providing current through an N-phase load, where N is a positive integer, the apparatus comprising:
Apparatus for providing a current through a load, the apparatus comprising:
Dependencies are inferred from the claim text.