초록 ▼

A control strategy for a multiple phase brushless motor (1) is disclosed in which the top (2, 3, 4) and the bottom (5, 6, 7) switching devices in two arms of the motor bridge are driven using complementary pulse width modulated waveforms, so that the top device (2, 3, 4) in one of the arms is in the

A control strategy for a multiple phase brushless motor (1) is disclosed in which the top (2, 3, 4) and the bottom (5, 6, 7) switching devices in two arms of the motor bridge are driven using complementary pulse width modulated waveforms, so that the top device (2, 3, 4) in one of the arms is in the ON state while the bottom device (5, 6, 7) is in the OFF state and vice versa. In an alternative arrangement, the control strategy described hereinbefore is used at high motor speeds while at low motor speeds a conventional modulation scheme is used in which a top switching device (2, 3, 4) in one arm of the bridge is in the ON state and a bottom device (5, 6, 7) in a different arm of the bridge is pulse width modulated. In another aspect, a method of calculating the position of the motor rotor is disclosed.

대표청구항 ▼

[ We claim:] [4.] A control strategy for controlling the pulse width modulation of a multiple phase brushless motor having three phases in which each phase of the motor is connected to an arm of a multi-phase bridge and each arm of said bridge comprises a top switching device, and a bottom switching

[ We claim:] [4.] A control strategy for controlling the pulse width modulation of a multiple phase brushless motor having three phases in which each phase of the motor is connected to an arm of a multi-phase bridge and each arm of said bridge comprises a top switching device, and a bottom switching device, said switching devices, comprising at least one transistor, wherein said control strategy selects from a first modulation mode and a second modulation mode:whereby in said first modulation mode, said top switching device and said bottom switching device in at least one arm of said bridge are driven by complementary pulse width modulated inputs applied to said top and bottom switching devices so that one of the said top and bottom switching devices is in the ON state whilst the other one of the top or bottom switching device is in the OFF state, and at the end of a said pulse width modulation duty cycle, the state of the said two switching devices is reversed;and whereby in said second modulation mode, a pulse width modulated input is applied to said bottom switching device in one of said arms of said bridge whilst said top switching device in a different one of said arms of said bridge is switched ON, selection of said pulse width modulation duty cycle and which of said switching devices are modulated being performed by a control algorithm.