LLC resonant converter and control method thereof

Abstract

The invention provides an LLC resonant converter capable of bidirectional operation, a primary side PWM control signal and a secondary side PWM control signal have the same switching period, so that each switching device of a primary side bridge circuit and each switching device of a secondary side bridge circuit are synchronously switched on and switched off. Optimal configuration of losses of the primary side bridge type circuit and the secondary side bridge type circuit is achieved by controlling the pulse width length of driving signals of all switching devices of the primary side bridge type circuit and all switching devices of the secondary side bridge type circuit, and then the temperature of a heat dissipation cold plate of the primary side bridge type circuit and the temperature of a heat dissipation cold plate of the secondary side bridge type circuit are controlled on line. Healthy and stable operation of the high-frequency LLC resonant converter is ensured. The invention further provides a control method of the LLC resonant converter.

Description

technical field [0001] The invention relates to the field of power electronics, in particular to an LLC resonant converter and a control method thereof. Background technique [0002] In recent years, with the continuous development of high-frequency power electronics technology, research on new power conversion technologies in the fields of renewable energy, electric vehicles, and electric traction has received extensive attention. In the field of power grids, new concepts such as AC and DC hybrid transmission and distribution networks, DC transmission and distribution networks, DC microgrids, power electronic transformers, and energy routers are constantly being proposed. In many of the above research hotspots and applications, DC with bidirectional energy flow is required. The / DC converter acts as an interface between DC buses of different voltage levels. At the same time, in order to ensure the high efficiency and high power density of the DC converter, the DC / DC conver...

AI Technical Summary

Problems solved by technology

When operating at high frequency, the power device of the secondary side bridge circuit has a large turn-off current and large turn-off loss, so the temperature of the secondary side is relatively high, while the temperature of the primary side is relatively low, which cannot be adjusted

When the surface of a single heat dissipation cold plate is maintained at a high temperature, in severe cases, the reliability and life of the power devices installed on the cold plate may be reduced

[0005] If the switching loss and temperature are reduced by reducing the operating frequency, when the frequency deviation is relatively large from the rated frequency, it is easy to cause the high-frequency transformer core to saturate, the current and magnetic field curve changes, and the normal steady-state operating point of the transformer is changed, causing the magnetic circuit to be damaged. Saturation and degaussing lead to a sharp drop in excitation inductance, and overcurrent spikes cause overcurrent, which will also damage the main circuit power device in severe cases

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