In-situ balance calorimeter for measurement of half-bridge power loss

An in-situ balance calorimeter is proposed for measuring power loss in half-bridge circuits. During the functional operation phase, the steady-state heat flux through the thermal path is recorded, while the case temperature is maintained at the ambient level by a thermoelectric cooler (TEC). In the balancing phase, in-situ heating is realized by harnessing switching losses arising from parasitic capacitance charging and discharging. Precise thermal control is achieved through adjustment of the hard-switching frequency of the half-bridge circuit to replicate the identical steady-state heat flux profile. The power loss is then determined as the product of the DC bus voltage and current. Since in-situ heating reconstructs the thermal field within the same physical structure, the long-term stability of measurement elements becomes unnecessary. Instead, measurement accuracy is ensured by short-term repeatability. A heat flux sensor formed by two low-cost, PCB-based surface RTDs monitors heat flux variations during both operational phases. The use of a solid thermal conduction path with very low thermal capacity and resistance results in an extremely small thermal time constant, enabling the system to attain thermal equilibrium within 1 min under thermal regulation in both phases. Experimental results demonstrate the effectiveness of the proposed method in achieving rapid thermal equilibrium and accurate power loss quantification.Q1: Upon a thorough review of the full manuscript, the abstract has been revised to more effectively highlight the innovative aspects of this research. The updated version offers a more precise and comprehensive overview of the study's core content and conclusions.