The fish method: an analytical tool for optimizing converter-machine performance

The quality of switching patterns for voltage source inverters is often judged by the higher harmonics of line-voltages, line-currents, and torque ripple. Because torque ripple is based by machine parameters, imperfect comparison is the consequence. The proposed fish method shows how, from a switching pattern, a unique and useful signature is derived. This graphical signature, called fish, is a representation of the integrated voltage vector in revolving coordinates. The fish dimensions, representing relative torque and current ripple, deliver a well defined machine-independent measure of quality, for analysis and synthesis of PWM switching patterns. The paper demonstrated a new switching pattern design method that strictly obeys any given minimum on-time constraint of the applied semiconductor switches and snubbers.<>