Digital Synchronous Rectification Control Method and Digital Signal Processor

Abstract

The invention provides a digital synchronous rectification control method, which is applied to an LLC resonant converter. A rectification circuit is connected to the secondary side of the LLC resonant converter, and the rectification circuit includes a plurality of switch tubes; the digital synchronous rectification control method comprises: according to the LLC resonant Various working modes of the converter and the constraints of each working mode, determine the load parameters of the LLC resonant converter, the load parameters include voltage parameters and current parameters; determine the current working mode of the LLC resonant converter according to the load parameters , the current working mode is one of multiple working modes; according to the switching frequency, load parameters and current working mode of the LLC resonant converter, determine the turn-on time or turn-off time of each switch tube in a specific period; According to the turn-on time or turn-off time of each switch tube in a specific period, the LLC resonant converter is controlled synchronously. By adopting the invention, the current on-off time of the rectifier tube can be accurately calculated in the full load range and synchronous rectification control can be performed.

Description

technical field [0001] The invention relates to the technical field of power conversion, in particular to a digital synchronous rectification control method and a digital signal processor. Background technique [0002] The LLC resonant converter has become one of the most widely used topologies in the DCDC topology due to its simple structure, high efficiency and good soft switching characteristics. The LLC primary side switch tube can be designed to achieve zero voltage switching (ZVS) in the full load range, and the switching loss is greatly reduced. However, in the application of low voltage and high current, the secondary side rectifier diode will produce non-negligible losses. Therefore, synchronous rectification technology is usually used, that is, a MOS tube with a small on-resistance is used instead of a diode to conduct, which greatly reduces the conduction loss of the LLC secondary side. [0003] Existing synchronous rectification schemes can be roughly divided in...

AI Technical Summary

Problems solved by technology

The hardware solution mainly uses a synchronous rectification chip, and needs to increase the voltage or current detection circuit, etc., which increases the system cost on the one hand, and on the other hand, due to the use of fixed hardware assistance, it will be difficult to achieve DCDC bidirectional switching applications; the software solution is mainly based on traditional FHA (First Harmonic Approximation, fundamental wave equivalent) model control or look-up table method, etc., the FHA model has a large error at the position away from the resonance point, so it cannot guide the accurate switching action of the rectifier tube. The look-up table method is measured through experiments. The data is fitted to obtain an approximate switching time of the rectifier tube. However, since there are often multiple modes during LLC operation, it is difficult to summarize the operation of the full load range by the look-up table method.

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