A novel and simple analytical technique for brushless motor modelling in the simulation of high performance industrial drives

A novel method of modelling the nonlinear electrodynamic behaviour of brushless motors for high performance industrial drive simulation is presented based on the unified Lagrangian equation of motion. This method eliminates the artificial coenergy concept for torque generation and the need for two separate sets of electrical and dynamic laws to explain motor operation. The electromechanical coupling field energy exchange mechanism is also simply explained by means of the work function concept indigenous to the analytic equation of motion. A single Fourier series description of pulsewidth modulated (PWM) inverter operation with dead time is included in the drive model description to reduce simulation time with a beneficial saving in computation resources. A fiftyfold reduction in simulation time is readily achieved with the Fourier PWM method without loss of simulation accuracy by comparison with the time step size necessary to accurately model PWM switching instants. Model accuracy and integrity are validated at several internal test nodes when simulation results, based on frequency modulated current traces, are checked for coherence against those for an actual drive system.