TABLE OF CONTENTS All of the electrical power directed to the hybrid propulsion M/G must pass through the power electronics. It has been said that control electronics uses power to process information and that power electronics uses information to process power. In this section we describe how power electronics is sized to match the electric machine to the vehicle energy storage system, via information processed by the control electronics.
Figure 4.13 is a schematic for the hybrid propulsion system ac drive system consisting of on board energy storage, power processing according to control algorithms, and traction actuation via the M/G and vehicle driveline.
The essentials of ac drive system operation are that power from a dc source such as a fuel cell, battery or ultra-capacitor is converted to variable voltage, variable frequency ac power at the M/G terminals, V ? and I ?. The M/G then converts this electrical power to mechanical power in the form of torque and speed at the transmission input shaft, T and ?. The power electronics is an electrical matching element in much the same manner that a gearbox processes mechanical power to match the engine to the road load requirements. The power inverter matches the dc source to the mechanical system regardless of torque or speed level, provided these quantities are within its capability.
The power processing capability of power inverters is directly related to the dc input voltage available. Higher...
