Pulse modulated control with field weakening for improved motor efficiency
AssigneeTula eTechnology, Inc.
InventorsPaul Carvell, Adya S. Tripathi
Life of this patent
Estimating the term…
Abstract
Modulated pulse control of electric machines to deliver a desired output in a more energy efficient manner by either (a) operating the electric machine in a continuous mode when a requested torque demand is greater than the peak efficiency torque of the electric machine or (b) in a pulsed modulation mode when the requested torque demand is less than the peak efficiency torque of the electric machine. When operating in the pulsed modulation mode, the inverter may be deactivated to further improve the system efficiency when field weakening is not required to mitigate or eliminate generation of a retarding torque in situations when Back Electromagnetic Force (BEMF) exceeds a supply voltage for the inverter of the machine.
Claims27
A method comprising:
- receiving a torque demand;
- operating a motor in a continuous mode if the received torque demand exceeds a threshold;
- operating the motor in a pulsed mode if the received torque demand is less than the threshold, the pulsed mode comprising a series of “on” and “off” time durations periods;
- while operating in the pulsed mode, determining if back electromagnetic force (BEMF) of the motor is more than a supply voltage applied to a power inverter used to excite the motor and during periods of time between “on” time durations periods when operating in the pulsed mode:
- (a) maintaining the power inverter activated, but demanding no torque, when the BEMF is more than the supply voltage applied to the power inverter, and applying field weakening to the motor;
- and
- (b) deactivating the power inverter when no field weakening is applied.
A motor assembly arranged to:
- apply field weakening during a pulsed mode operation of a motor of the assembly when back electromagnetic force (BEMF) of the motor exceeds a supply voltage provided to an inverter that is used to excite the motor;
- maintain the inverter activated during periods of time between pulses when field weakening is applied, but with zero demanded torque;
- and
- maintain the inverter in a deactivated state during periods of time between pulses when field weakening is not applied.
A motor assembly arranged to operate in at least three modes, the three modes including:
- (a) a continuous mode when a torque demand requested for the motor exceeds a threshold;
- (b) a first pulsed mode wherein an inverter used to excite the motor is deactivated during periods between pulses when (i) the torque demand is less than a threshold torque and (ii) back electromagnetic force (BEMF) of the motor is less than a supply voltage provided to the inverter;
- and
- (c) a second pulsed mode with the inverter turned activated, but no torque is demanded during periods between pulses when (i) the torque demand is less than a threshold torque and (ii) back electromagnetic force BEMF of the motor is more than the supply voltage provided to the inverter.
Dependencies are inferred from the claim text.