An induction machine is driven to operate as a generator, and has its electrical output conductors coupled to a switching system, which can be an inverter circuit. An oscillator and logic circuit are connected to regulate the switching of the power switches, such as thyristors, in the inverter circuit which operates as a switching system. The thyristors in the switching system are regulated to switch at a frequency sufficiently below the synchronous frequency of the induction machine to enable the machine to build up and operate as a generator. A modulator is connected to the oscillator to vary the oscillator frequency, and thus change the switching frequency of the switching system, above and below a reference level to provide a corresponding a-c output voltage, with a d-c average level, on the d-c bus conductors of the inverter circuit which operates as the switching system. The amplitude and frequency of the a-c output voltage are controllable over a wide range of variations in both the shaft speed of the induction machine and/or the electrical load. The system is also capable of producing an a-c voltage and a separate d-c voltage, and both the a-c and d-c voltages can be separately controlled.
An electric power generating device including an induction type electric rotating machine rotating in interlock with an engine comprises an inverter connected at the AC side to and end of an armature winding and at the DC side to an electric power storing device, a detecting means for detecting the quantity of state related to the electric power generating voltage of the induction type electric rotating machine excluding the measured RPM of the induction type electric rotating machine but including the electric power storing voltage of the electric power storing device, and an electric power generation controlling means for maintaining the electric power storing voltage within the preset range by controlling the frequency of the controlling voltage of the inverter based on the quantity of state related to the electric power generating voltage. This electric power generating device can control the electric power generation without using any RPM detecting device for the induction electric machine, and as a result, the composition of the device can be simplified. The frequency can be controlled so that the frequency can be changed in the direction in which the difference between the electric power storing voltage and the preset reference voltage is reduced.
A variable speed constant frequency generating system for generating constant frequency electrical output power from a variable speed source of motive power includes an exciter for generating excitation current, a main generator for developing the output power, both of the exciter and main generator being driven by a shaft coupled to the motive power source and power converters mounted on the shaft to transfer power between the exciter and the main generator. At shaft speeds below synchronous speed, i.e. that speed which would produce the desired output frequency when DC power is coupled to the main generator field windings, the exciter output is rectified and inverted so that alternating current power of proper frequency is delivered to the field windings of the main generator to maintain the output of the generator at a constant frequency. At synchronous speed, the power converters transfer substantially only DC power to the main generator windings. At speeds above synchronous speed, power is returned back to the exciter to cause same to operate as a motor and apply negative torque to the shaft and thereby maintain the output power at the desired frequency.
A control system for an electric motor having an integral flywheel rotor. The motor includes a stator mounted co-axially with the engine crankshaft and a rotor surrounding the stator. A sensor is positioned near the rotor for sensing its rotational speed. The sensor is coupled to a controller. The controller is operable to deliver an output signal to the stator to start the internal combustion engine. While the engine is starting, the processor steps the starter motor from a low speed to a high speed. Once the engine has started and is rotating at a speed greater than a trigger speed, the processor delivers another output signal such that the motor is commutated at a speed that is less than the speed of the rotor to generate a speed slip. By commutating the motor in this manner, it acts as a generator. The speed slip is regulated when the motor is generating electric power so that the motor produces a constant output voltage.
