Patent ID: 7894224
Filing Date: 2011-02-22
Classification: H02M

Abstract:
1. A voltage drive system having a single-phase output signal to drive a load, the voltage drive system comprising: a plurality of modulators and a plurality of switching circuits; wherein, a first of the modulators receives a phase current error reflecting a difference between a current reference and a current value of the single-phase output signal, and generates a first gate input based on the phase current error, the first modulator including a first signal generator generating a first reference signal having a first phase, and a first adder receiving the phase current error and the first reference signal; a second of the modulators receives the phase current error and generates a second gate input based on the phase current error, the second modulator including a second signal generator generating a second reference signal having a second phase different from the first phase, and a second adder receiving the phase current error and the second reference signal; a first of the switching circuits receives the first gate input and generates a first output terminal voltage based on the first gate input; a second of the switching circuits receives the second gate input and generates a second output terminal voltage based on the second gate input, and wherein, the first adder generates a first modulated phase current error based on the phase current error and the first reference signal; the second adder generates a second modulated phase current error based on the phase current error and the second reference signal; the first modulator changes the first gate input from a first voltage level to a second voltage level to effectively cause a first switching event of the first switching circuit when the first modulated phase current error changes from being within a predetermined current range to being outside of the predetermined current range; the second modulator changes the second gate input from a third voltage level to a fourth voltage level to effectively cause a second switching event of the second switching circuit when the second modulated phase current error changes from being within the predetermined current range to being outside of the predetermined current range; the plurality of switching circuits is cascaded such that the switching circuits of the plurality of switching circuits collectively generate the single-phase output signal to the load, and a voltage of the single-phase output signal is equal to a sum of an output terminal voltage of each of the plurality of switching circuits.