Low Power DEAP Actuator Drive for Heating Valves

Abstract

Modern heating systems play a key role in providing comfortable living environment and saving energy. The radiator heating valve and thermostat are essential elements to achieve the temperature control in the dwelling space. The existing actuator inside the thermostat either suffers from the operation noise issue, or cannot realize the accurate temperature regulation and remote control. Due to the advancement of the material science, in recent years, a new type of smart material, called DEAP (Dielectric Electro Active Polymer), gradually attracts the attention of researchers. The superior performances of DEAP actuator, such as noise free operation, high energy density, quick response time, etc, make it a possible solution to replace the conventional actuators inside the thermostat. To operate the DEAP actuator in the heating system and considering its intrinsic properties, a driver featuring high output voltage and capacitive load charging ability has been investigated. High voltage flyback converter is proved to be an applicable solution in the heating valve application. The conventional flyback topology and the multiple transformers based primary parallel secondary series flyback converter (PPSSFC) featuring the unidirectional energy flow are investigated in terms of fundamental working principle and practical implementation. The converter with bidirectional energy flow functionality is desired to improve the overall efficiency and has been studied as well. The design guidelines of the high voltage flyback transformer in capacitive load charging and discharging application are proposed. In order to achieve the thorough understanding of the converter, a switching cycle based analytical model for both charging mode and discharging mode have been established. Based on this, the energy efficiency analysis has been carried out to achieve efficiency calculation model. Moreover, two system level control schemes are proposed to achieve the corresponding temperature control. The functionality and energy consumption of the high voltage driver have been verified through the test in the practical heating system with the radiator heating valve and the implemented DEAP actuator. The implemented high voltage flyback converters can achieve relatively low volume and satisfactory efficiencies. In addition, the switching cycle based analytical model and the energy efficiency analysis can be used to well predict the behaviour and efficiency in both charging and discharging mode. The system level energy consumption is relatively low when the burst mode control scheme is applied. If 2.5 Ah batteries are employed, the high voltage driving system with bidirectional converter can run for around 2.1 years.