A Novel Control Method for LLC Converter under Short-circuit Condition

Abstract

For the aviation power supply system, high reliability, high efficiency and high power density are the three important requirements. In the short-circuit condition of aviation LLC converter, because the output voltage is small and the output current is large, the synchronous rectification technology can greatly reduce the loss, and it is particularly important to accurately control the on time and off time of synchronous rectifier. However, under LLC short-circuit condition, due to the shorter dead-time required for the primary side to realize ZVS, the secondary side does not turn on the synchronous rectifier while the current approaches the maximum value, resulting in more losses. This paper proposes a digital synchronous rectification control method of LLC converter under short-circuit condition, which can better control the synchronous rectifier by compensating the dead-time. Finally, the synchronous rectification compensation method is applied to the LLC short-circuit experiments of 150A and 200A respectively, and good control is obtained, which verifies the feasibility of the digital synchronous rectification control method.