Numeric control method for liquid level control (LLC) resonant conversion circuit

Abstract

The invention discloses a numeric control method for a liquid level control (LLC) resonant conversion circuit. The method comprises the following steps of: sampling an LLC series resonant conversion circuit and an inverter electrically connected with the LLC series resonant conversion circuit respectively by adopting a single voltage loop numeric control structure; after calculation, outputting to a numeric controller; calculating the input quantity by using the numeric controller and outputting a driving pulse; controlling the LLC series resonant conversion circuit by using the driving pulse through a driving circuit; during light load or no load, adopting a mode of combining a pulse width modulation (PWM) control strategy and a pulse frequency modulation (PFM) control strategy; and during heavy load, adopting the PFM control. By the method, load states can be judged quickly; adverse influence on system load judgment due to different loading time is screened; a dynamic working point is selected reasonably according to the judged load state and current is controlled, so that the voltage stress of the LLC series resonant conversion circuit is eliminated; the control method provided by the invention is simple; and error and instability can be effectively reduced.

Description

technical field [0001] The invention relates to a resonant conversion circuit, in particular to a digital control method suitable for an LLC series resonant conversion circuit. Background technique [0002] The resonant converter has been widely studied and concerned in the application of switching power supply technology due to its advantages of high power, high efficiency, and high power density. As a special circuit topology, the LLC series resonant converter circuit can not only meet the requirements of high frequency , and can achieve high conversion efficiency, it has been widely adopted in the industry. The LLC series resonant conversion circuit commonly used in engineering is generally used in step-down occasions, and its application has been relatively mature. The application of the step-up converter as a DCDC part in a single-phase UPS (uninterruptible power supply) is relatively rare, especially when the load it carries is a single-phase inverter. The following ...

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Problems solved by technology

[0005] The main purpose of the present invention is to solve the problems in the prior art, and provide a digital control method of the LLC resonant conversion circuit with a simple control method, so as to solve the problem that UPS is difficult to realize the LLC series resonant conversion circuit in the prior art

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