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Current mode switching for tri-state amplifiers in magnetic bearing control systems

  • US 6,005,316 A
  • Filed: 12/10/1998
  • Issued: 12/21/1999
  • Est. Priority Date: 04/11/1997
  • Status: Expired due to Term
First Claim
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1. A method of controlling switching of a tri-state switching amplifier having two switching legs, two switches in each leg, and a load connected to the junction between the switches of each leg, a power supply and a capacitor connected to the opposite ends of each leg, a first pair of said switches defining an idle state in which current circulates through said load and said first pair of switches, a second pair of said switches defining a Charge state in which said load is connected to said power supply and current through said load increases and a third pair of switches defining a Discharge state in which said load is connected to said power supply and current through said load decreases, comprising:

  • (a) generating a first PWM signal at the beginning of each pulse of a clock signal;

    (b) generating a second PWM signal when a binary current error signal changes state;

    (c) generating, at the beginning of each pulse of said clock signal, a Direction signal which is the inverse of said current error signal; and

    (d) placing said amplifier in said idle state when said second PWM signal is present and otherwise placing said amplifier in said Charge state for one state of said Direction signal and placing said Amplifier in said Discharge state for the other state of said Direction signal.

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