Patent ID: 7218072
Filing Date: 2007-05-15
Classification: H02P

Abstract:
1. A motor driving device comprising: (a) a motor including three-phase driving coils; (b) a power feeder for feeding power to said driving coils, the power feeder including an upper arm transistor and a lower arm transistor corresponding to each of the respective coils; and (c) a power feeding controller for controlling a method of feeding power by said power feeder to said driving coils during a first feeding period and during a second feeding period, wherein said first feeding period corresponds to driving the motor from a motor halt status up to and including a predetermined speed and said second feeding period corresponds to driving the motor above the predetermined speed, during said first feeding period, said power feeder controller controls electrical potentials of a respective coils during its respective driving period by a pulse width modulation (PWM) function by applying a voltage to said coils, such that the voltage applied to said coil equals alternately to one of a power supply voltage potential or a grounding potential by cycling between 1) turning on the upper arm transistor and turning off the lower arm transistor, and 2) turning off the upper arm transistor and turning on the lower arm transistor, cycling between 1) and 2) the first PWM function while one or the lower arm transistors is turned on, and during said second feeding period, said power feeder controller controls the electrical potentials of the said coil during its respective driving period by a second PWM function such that the voltage is applied to said coil is equal alternately to one of a power supply voltage potential and an open circuit applying the voltage to said driving coils, such by cycling between 1) turning on the upper arm transistor and 2) turning off the upper arm transistor to the driven coil, but turning off and leaving off the respective lower arm transistor to the driven coil, cycling through 1) and 2) of the second PWM while one of the lower arm transistors of a coil different from the driven coil is turned on, wherein the transistor switching is performed without coupling the coils to each other via the upper arm transistor or the lower arm transistor.