Patent ID: 6664750
Filing Date: 2003-12-16
Classification: H02M,H02P

Abstract:
A method of operating an H-shaped bridge coil driver circuit, connected to a power supply, for driving a connectable motor coil in an electronically commutated brushless D.C. motor, under the control of signals input to said H-shaped circuit, said H-shaped circuit having a left and right side legs of two serial leg segments, with a switch located each therein, and with said connectable coil forming the cross leg thereof, said H-shaped circuit being connected to said power supply at the top of each side leg and to ground at the bottom of each side leg, said H-shaped circuit also including alternate current path voltage protection elements connected one each in parallel across a respective lower leg segment side switch, comprising the steps of:connecting said leg segment switches to operate in first and second cross-diagonal pairs and controlling said cross-diagonal switch pairs in alternate conduction states; closing said first cross-diagonal leg segment switch pair and simultaneously opening said second cross-diagonal leg segment switch pair during a first time period to cause current to flow from said power supply through said connectable coil in a first direction; closing said second cross-diagonal leg segment switch pair and simultaneously opening said first cross-diagonal leg segment switch pair during a second time period to cause current to flow from said power supply through said connectable coil in a second opposite direction; repeating the first and second closing and simultaneous opening steps to provide repeatedly successive first and second time period cycles; permitting the lagging excess energy in said connectable coil to freely discharge therefrom at the beginning of each successive time period by establishing a separate current path to a separate voltage storage element which is charged by the flow of said lagging excess coil energy, whereby during said storage element charging the current in the connectable coil continues in its previously established direction from the previous time period; establishing a current path from said separate voltage storage element back to said power supply to discharge said storage element back into said power supply; and permitting the discharge from said separate voltage storage element to provide the current to said coil thereby relieving the power supply until said voltage storage element voltage falls below that of the power supply.