A “power-mapping” variable-speed control technique for a constant-frequency conversion system powered by a IC engine and PM generator

A variable-speed power conversion system is considered where a permanent magnet generator (PMG) driven by an IC engine supplies power to an electronic inverter. The AC voltage from the PMG is typically diode-rectified into a DC link, which is utilized by the inverter to produce constant-frequency, constant-voltage output. These “electronic gensets” can be smaller, lighter and have higher performance than their fixed-speed counterparts with synchronous alternators under field control. Such attributes are attractive for mobile and stand-by power applications. The added flexibility of a variable-speed genset system must be met with suitable techniques for directing the speed at which the engine should operate for a given electrical load. Constraints on torque, speed, and DC link voltage must additionally be met. This paper reviews conventional methods, and presents a new technique utilizing the operating power of the system as an input to a power-speed “map” for the system to follow. Experimental results are included