A Transient Diesel Test Bed with Direct Digital Control

A computer controlled test bed is described, developed for transient testing of diesel engines. Objectives achieved have been rapid response, good accuracy and repeatability flexibility for testing different engines, minimum hardware cost and concurrent rapid data logging for research purposes. Eddy current dynamometers are used with pulsed voltage excitation for rapid response. Stepping motors are used for “throttle” control with software pulse generation.

Control is via software based on dynamometer and stepping motor models for time optimal algorithms. Preview can be used to improve accuracy on prescribed test cycles. Results for step Inputs, power-speed law control and disturbance rejection tests are presented with special emphasis on the Interaction between engine and control system characteristics.