Step switched PWM sine generator
First Claim
1. Apparatus for producing a high voltage waveform corresponding to a target waveform using low voltage components comprising:
- a. a pulse width modulator for providing an output having a relative magnitude of one in the form of a succession of pulse train segments, each having an envelope conforming to successive corresponding segments of the target waveform;
b. a first square wave generator connected to the pulse width modulator, and providing a bipolar square wave output having at least three output states;
c. a second square wave generator connected to the first square wave generator, and providing a bipolar square wave output having at least three output states wherein the pulse width modulator and the first and second square wave generators are connected in series relationship, and further wherein the relative magnitude of one of the square wave generator outputs is six and the relative magnitude of the other square wave generator is two; and
d. a control means connected to;
i. the pulse width modulator for controlling the pulse width modulator to deliver the succession of pulse train segments separated by a plurality of transitions between segments, and ii. the first and second square wave generators for switching the respective bipolar square wave outputs from one state to another of the output states during each transition between successive segments, such that the output of the pulse width modulator is added to the outputs of the square wave generators to form a high voltage waveform output made up of the square wave outputs of the step wave generators and the segmented waveform output of the pulse width modulator.
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Accused Products
Abstract
Apparatus for generating a high time-varying AC voltage using low voltage power semiconductors arranged in series bridge circuits, each powered by an independent DC source. At least one bipolar output pulse width modulation bridge circuit and at least a pair of bipolar output square wave generator bridge circuits have their outputs added together and passed through a low pass filter to form a time-varying, typically sinusoidal, AC output waveform. A first square wave generator has an output with a relative magnitude of 6, a second square wave generator has an output with a relative magnitude of 2 and the pulse width modulator has an output with a relative magnitude of 1. Additional square wave generators of relative magnitude 6 may be added to increase the output voltage.
80 Citations
28 Claims
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1. Apparatus for producing a high voltage waveform corresponding to a target waveform using low voltage components comprising:
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a. a pulse width modulator for providing an output having a relative magnitude of one in the form of a succession of pulse train segments, each having an envelope conforming to successive corresponding segments of the target waveform;
b. a first square wave generator connected to the pulse width modulator, and providing a bipolar square wave output having at least three output states;
c. a second square wave generator connected to the first square wave generator, and providing a bipolar square wave output having at least three output states wherein the pulse width modulator and the first and second square wave generators are connected in series relationship, and further wherein the relative magnitude of one of the square wave generator outputs is six and the relative magnitude of the other square wave generator is two; and d. a control means connected to;
i. the pulse width modulator for controlling the pulse width modulator to deliver the succession of pulse train segments separated by a plurality of transitions between segments, and ii. the first and second square wave generators for switching the respective bipolar square wave outputs from one state to another of the output states during each transition between successive segments, such that the output of the pulse width modulator is added to the outputs of the square wave generators to form a high voltage waveform output made up of the square wave outputs of the step wave generators and the segmented waveform output of the pulse width modulator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of forming a high voltage time-varying waveform comprising the steps of:
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a. connecting a pulse width modulator having a bipolar output with a relative magnitude of ±
1 unit in series in series with a first step wave generator having a bipolar output with a relative magnitude of ±
6 units and a second step wave generator having a bipolar output with a relative magnitude of ±
2 units;
b. controlling each step wave generator to successive +ON, ZERO, and −
ON states, while simultaneously controlling the pulse width modulator to provide a pulse train having an envelope corresponding to a plurality of successive segments of a desired time-varying waveform; and
c. passing the combined output of the pulse width modulator and step wave generators through a low pass filter such that the resulting output is a time-varying waveform having a peak voltage equal to the sum of the outputs of the pulse width modulator and the step wave generators. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28)
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Specification