The basic components of a control scheme for a dynamical combustion engine test stand are described. A model of the dynamometer obtained by application of theoretical modelling together with parameter estimation techniques is used for design of a torque regulator and simulation of different control schemes. The time-delay of the current converter has a determining influence on achievable simulation quality. A smaller time-delay allows improved torque control behaviour and less problems with stability of the closed simulation loop. Therefore, control performance can be increased by replacement of the digitally controlled current converter with an analogue controlled one. As modern combustion engines are characterized by an increasing number of cylinders and decreasing moment of inertia, higher and higher simulated resonance frequencies are demanded. Improving performance of dynamometer torque control is the only way to attain that goal. The whole control scheme is realized on a VMEbus computer system. It consists of a main processor equipped with a Motorola 68020, analogue and digital I/O boards and a slave processor with graphical I/O facilities for user interface purposes.
展开▼
