Patent ID: 6153989
Filing Date: 2000-11-28
Classification: H02P

Abstract:
A motor driver for a multi-phase wound electric motor having a rotor and multiple phase coils arranged as a stator, each phase coil having a first terminal and a second terminal, wherein the first terminals of the phase coils are connected together at a center tap, the motor driver comprising:(a) a commutation phase generation means responsive to BEMF voltages in the phase coils for generating commutation state signals corresponding to a sequence of commutation states for selecting at least a first and a second coil in each commutation state, such that when energized said at least first and second coils are capable of providing forward torque to the rotor based on the rotational position of the rotor relative to the phase coils;(b) a coil driver for energizing the phase coils, the coil driver comprising:(1) a driver circuit responsive to said commutation state signals and to current control signals including a first control signal, a second control signal and a deceleration control signal, for energizing said at least first and second coils, wherein in each commutation state:(i) in response to the first control signal the driver circuit electrically connects the second terminal of the first coil to an upper voltage supply by establishing a first current path from the upper voltage supply to the second terminal of the first coil; and(ii) for applying forward torque to the rotor, in response to the second control signal the driver circuit electrically connects the second terminal of the second coil to a lower voltage supply by establishing a second current path from the lower voltage supply to the second terminal of the second coil, wherein the upper voltage supply is at a higher voltage level than the lower voltage supply, thereby causing a forward current to flow in the first and second coils to provide forward torque to the rotor;otherwise, in response to the deceleration control signal for applying reverse torque to the rotor, the driver circuit electrically connects the second terminal of the second coil to the upper voltage supply during at least a portion of each commutation state by establishing a third current path from the upper voltage supply to the second terminal of the second coil, to allow BEMF induced currents to flow in the first and second coils, causing reverse torque to the rotor; and(2) a speed control circuit for:(i) generating said first and second control signals to control the level and direction of the currents flowing in the first and second coils in each commutation state, and(ii) generating the deceleration control signal in response to a deceleration command for decelerating the rotor during at least a portion of each commutation state, whereby the driver circuit establishes the third current path during said at least a portion of each commutation state to allow BEMF induced currents to flow in the first and second coils, causing reverse torque to the rotor.