22 May 2002
Two concepts of a new control approach for heat pump heating systems are presented. Instead of conventionally controlling either the supply or the return flow temperature in function of outdoor temperature, the new approach directly delivers in adequate portions the heating energy required into the house utilizing a pulse width modulation. The first simpler concept mainly uses the steady-state energy demand of the house, whereas the more sophisticated second concept additionally uses the thermal dynamics of the house. This paper focuses especially on the second concept. It is shown that thermal dynamics of the house, the weather forecast, the power tariff structure, and power cut-off times may be taken into account to optimize both the comfort and an energy or cost efficient operation of the heat pump. Simulation results show that a good comfort level can be achieved with a reduction of power costs of 10% compared to the operation with a commercial relay-type controller. This control concept was implemented in a production-type controller that could be tested successfully as a prototype controller in a single-family house.