Regenerative braking of battery powered converter controlled PM synchronous machines

The powertrains of hybrid electric vehicles incorporate motor-generator units that can contribute propulsion torque or braking torque in response to driver demands and power management logic. A key feature of these motor-generator units is their ability to recover kinetic energy, through regenerative braking, that would otherwise be dissipated as heat. This paper clarifies and resolves several critical issues relating to regenerative braking of battery powered converter controlled permanent-magnet synchronous machines, including the determination of boundaries in the torque-speed plane defining the regenerative braking capability region and the determination of feasible operating points within that capability region that lead to maximum battery-pack recharge current.