US 7,570,037 B2
Hybrid control methods for digital pulse width modulator (DPWM)
Jian Li, Blacksburg, Va. (US); Dong S. Ha, Blacksburg, Va. (US); Yang Qiu, Blacksburg, Va. (US); Ming Xu, Blacksburg, Va. (US); and Fred C. Lee, Blacksburg, Va. (US)
Assigned to Virginia Tech Intellectual Properties, Inc., Blacksburg, Va. (US)
Filed on Nov. 17, 2006, as Appl. No. 11/561,104.
Prior Publication US 2008/0116871 A1, May 22, 2008
Int. Cl. G05F 1/575 (2006.01); G05F 1/618 (2006.01)
U.S. Cl. 323—283 21 Claims
OG exemplary drawing
 
1. A digital pulse width modulator comprising
a switching circuit connected to an input voltage source, and
a control circuit for establishing a duty cycle of said switching circuit, said control circuit comprising at least one of:
a clock circuit for establishing a constant number of time slots during which said switching circuit will be on or said switching circuit will be off during a switching cycle of said switching circuit, and means for adjusting a number of time slots in a said switching cycle of said switching circuit; and
two clock circuits operating at different frequencies and synchronized in a switching period of said switching circuit, and means for calculating a leading edge time in accordance with an output of one of said two clock circuits and a trailing edge time in accordance with an output of one of said two clock circuits to provide a desired pulse width within a said switching period of said switching circuit.