Feedback control system having predictable open-loop gain
AssigneeVLT, Inc.
InventorsPatrizio Vinciarelli, Louis A. Bufano
Life of this patent
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Abstract
A closed-loop feedback system has first and second gain elements. The first gain element has a transfer function such that Xd=Kg * (Xcont).sup.z, where Xcont is a control variable input signal of the first gain element, Xd is a controlled variable output signal of the first gain element, and Kg and z are independent of Xcont. The second gain element has a transfer function h1 such that Xcont=h1(Xe) where Xe is a control variable input signal of the second gain element and Xcont is a controlled variable output signal of the second gain element. The function h1 is of a form which satisfies [1/h1(Xe)]*[.delta.h1(Xe)/.delta.Xe]=Ke, where Ke is independent of Xe.
Claims51
A closed-loop feedback system comprising
- a first gain element having a transfer function such that Xd=Kg * (Xcont).sup.z, where Xcont is a control variable input signal of the first gain element, Xd is a controlled variable output signal of the first gain element, and Kg and z are independent of Xcont, and
- a second gain element having a transfer function h1 such that Xcont=h1(Xe) where Xe is a control variable input signal of the second gain element and Xcont is a controlled variable output signal of the second gain element,
- wherein the function h1 is of a form which satisfies [1/h1(Xe)]*[.delta.h1(Xe)/.delta.Xe]=Ke
- where Ke is independent of Xe.
A closed-loop feedback system comprising
- a first gain element having a transfer function such that Xd=Kg* (Xcont).sup.z, where Xcont is a control variable input signal of the first gain element, Xd is a controlled variable output signal of the first gain element, and Kg and z are independent of Xcont,
- a second gain element having a transfer function h1 such that Xcont=h1(Xe) where Xe is a control variable input signal of the second gain element and Xcont is a controlled variable output signal of the second gain element, the second gain element comprising circuitry having a gain proportional to the average value of the output of the second gain element, and
- as an input to the system, a setpoint value, Xref, indicative of a desired value for an output signal, Xd, of the system,
- the open loop gain of the system being substantially equal to Aol=z*,Ke*,Xd over a range of frequencies.
A power conversion system for converting power from a source for delivery to a load, the conversion system comprising a closed-loop feedback system having
- a power converter having a transfer function such that Xd=Kg* (Xcont).sup.z, where Xcont is a control variable input signal of the power converter, Xd is a controlled variable output signal of the power converter, and Kg and z are independent of Xcont,
- a controller having a transfer function h1 such that Xcont=h1(Xe) where Xe is a control variable input signal of the controller and Xcont is a controlled variable output signal of the controller, the controller comprising circuitry having a gain proportional to the average value of the output of the controller, and
- as an input to the system, a setpoint value, Xref, indicative of a desired value for an output signal, Xd, of the system,
- the open loop gain of the system being substantially equal to Aol=z*Ke*Xd over a range of frequencies.
A method of causing a closed-loop feedback system to have a generally constant value of open-loop gain, the system being of the kind that has
- a first gain element having a transfer function such that Xd=Kg * (Xcont).sup.z, where Xcont is a control variable input signal of the first gain element, Xd is a controlled variable output signal of the first gain element, and Kg and z are independent of Xcont, and
- a second gain element having a transfer function h1 such that Xcont=h1(Xe) where Xe is a control variable input signal of the second gain element and Xcont is a controlled variable output signal of the second gain element, the method comprising
- causing the transfer function h1 to have a form which satisfies [1/h1(Xe)]*[.delta.h1(Xe)/.delta.Xe]=Ke
- where Ke is independent of Xe.
Dependencies are inferred from the claim text.