Energy optimal control of thermal comfort in trams

Abstract

This paper presents a method for thermal comfort control for trams which achieves the desired thermal comfort and minimises the power consumption of heating, ventilation and air conditioning (HVAC). Mathematical models of all relevant parts are stated (these parts being the tram and the HVAC considering both comfort and energy consumption) and these models are linearised. Using linearised models, cascaded control loops are established. A model-predictive controller regulates the thermal comfort inside the tram as a master controller and outputs an auxiliary control variable to the slave controller. A heuristic, realised as mixed-integer optimisation, converts the auxiliary control variable in an energy-optimal way into switching commands for the HVAC. For validation, the method is implemented on a rapid controller prototyping platform. Testing of the control approach is done during several climatic wind tunnel measurements. The annual energy consumption is extrapolated using these results.