Abstract:
A MOSFET (50, 51) control topology and a physical structure for a motor control which provide a more efficient and economic DC motor control are disclosed. The control topology introduces a synchronous-rectification technique wherein free-wheel diodes are replaced with MOSFET (50, 51) devices that are switched on and off by a logic circuit (38) so that they are conductive for commuting motor current during periods that the motor (24) current supply is switched off. The physical structure and method of assembling a DC motor control (33) eliminate time consuming assembly techniques while ensuring effective waste heat exchange between electronic components (46, 50, 51) and a heat sink (96) of the control (33) by providing quick-install spring retainers (110) for urging the components (46, 50, 51) into heat conducting contact with the heat sink (96). The physical structure also provides for high density packing of electronic components (46, 50, 51) in the control (33).
Abstract:
Optimal constructions for two motor/controller configurations (20) are disclosed. The controller structure includes an H-bridge (48) for controlling field current using synchronous-rectification of MOSFET (58, 60, 62, 64) devices, and a circuit for chopping the armature (36) current using synchronous-rectification of MOSFET (44, 46) devices arranged in a half bridge. The controller (20) may be configured with a series-wound or a separately excited DC traction motor. In the series-wound motor/controller configuration, the field (38) and the armature (36) current are separately controlled. In the separately excited motor/controller configuration, the field (38) of the motor is preferably wound so that the rated field current is achieved at about 20 % of the rated battery voltage. This provides a separately excited motor in which the field current can be boosted by a factor of 5 to achieve high start-up and low speed torques which match the torque outputs of a series-wound motor under similar operating conditions.