Lear Avia Corporation

Lear Motors Corporation

Jack E Greenwell

Alexander Prokop

An inverter circuit for use in connection with loads such as motors and transformers is disclosed. The inverter includes separate precharge circuitry for precharging the commutating capacitor, clamping diodes for clamping the voltage on the inverter power elements to the precharge voltage level, and steering diodes for coupling the motor or transformer to the SCRs. The steering diodes allow the commutating capacitors to be charged to a precharge voltage level which is selected to be at least twice the maximum voltage to be applied to the load. The clamping diodes, by limiting the maximum voltage on the inverter power components, allows the use of components of substantially reduced voltage ratings. The precharge circuit provides reliable commutation at low motor speeds and voltage levels. Other embodiments and improvements are disclosed.

Motor drive circuit

A starter-motor, and alternator-generator apparatus for an internal combustion or gas turbine engine wherein the major electro-magnetic circuit of the apparatus is utilized for both the starting and generating functions is disclosed. The rotor may have two windings on it, a main rotor winding that acts as both a starter armature winding and an alternator field winding, and a small exciter armature winding. For slip ring machines the exciter is eliminated. The main rotor winding is wound in progressive simplex lap. The exiter armature or slip rings are connected to this winding at the equalizer connections through a rectifier and automatically activated switch circuit. During starter-motor operation, the main rotor winding is connected in series with its starter field winding through a commutator in a conventional series connected DC machine, and the exciter-armature winding or slip rings are disconnected from the main rotor winding. During alternator-generator operation, the brushes are lifted off the commutator and the exciter-armature winding or slip rings are connected to the main rotor winding.

Starter motor-alternator apparatus

A high speed hand held polyphase motor and a control system therefor is disclosed. The motor is of the induction type, designed for use in oral surgery and the like. The control system includes a bridge type inverter having a separate pair of solid state switching devices such as transistors connected in a bridge configuration across a pair of direct current power supply conductors for each phase winding of the motor. A switch control circuit is connected between the solid state switches and a variable frequency clock signal generator for turning the switches of each pair on and off in a given phase sequence to provide three phase current for the motor windings. The speed of the motor is proportional to the clock signal frequency. A voltage regulating circuit is connected between the power supply conductors and a source of direct current voltage to supply a direct current voltage across the supply conductors which varies in accordance with the clock signal frequency over a pre-established range. The control system further includes a torque demand adjustment circuit coupled to the voltage regulating circuit to permit the voltage across the supply conductors to be independently adjusted over a preset range of clock signal frequency.

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Reno, NV, United States of America

Jack E Greenwell