Cascade Control for the Variable Capacity of Gas Engine-Driven Heat Pumps

Variable compressor rotary speed is one of the most effective methods for capacity adjustment of heat pump. The cascade control is proposed for capacity adjustment of Gas Engine-Engine Driven Heat Pump (GEHP). Firstly, the general cascade control structure of GEHP is described which includes two control loops, primary loop and secondary loop, and then the dynamics responses of cascade control system are studied by completing the theoretical analysis and simulation. The results of theoretical analysis and simulation show that: compared with single loop control, cascade control can improve control quality, suppress the disturbances entering the engine rotary speed control loop effectively, and limit the effect of engine gain variation on the primary loop control process.