Hybrid Modulation for Balancing Thermal Dissipation in Dual Active Bridge Converters

High thermal stress on the power semiconductor device is one of the main causes of the power electronics converter failures. Due to an imperfect design of the hardware circuit in practice and parameter variations in volume production, the problem of unbalanced thermal stress often appears on the power semiconductor devices. For addressing this issue, active thermal control is usually utilized to reduce the thermal loading of the most stressed power semiconductor device and thus improve the converter reliability. In dual active bridge (DAB) converters, the most often utilized modulation method is phase-shift PWM control. On this basis, it is possible to mitigate the thermal loading of the most stressed device by rerouting the current flowing path. In this letter, a hybrid modulation method is presented by combining the conventional extended-phase-shift (EPS) modulation and the proposed modified EPS modulation. A 1.5 kW converter prototype is established and comparative experimental results are shown to validate the effectiveness of the hybrid modulation to do thermal management.