Switching frequency adjusting method based on current cross feedback

A technology of cross feedback and switching frequency, which is applied in the direction of adjusting electrical variables, control/regulation systems, and converting DC power input to DC power output, etc., to achieve the effects of simple and effective control, good stability, and good power sharing effect

CN105576981AActive Publication Date: 2016-05-11BEIJING INSTITUTE OF TECHNOLOGYGY
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Patent Information

Authority / Receiving Office
CN · China
Current Assignee / Owner
Publication Date
2016-05-11

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Abstract

The invention relates to a switching frequency adjusting method based on current cross feedback, aims to solve the problem of power sharing control for input-series-output-parallel (ISOP) modular LLC (Logical Link Control) resonant DC-DC (Direct Current-Direct Current) converters, and belongs to high-voltage direct-current input applications in the field of power electronics. According to the method, output voltages and output currents of modules are sampled, and switching frequencies of the modules are adjusted through cross current feedback and kept within a range in which input impedance of an LLC converter monotonically increases progressively along with the switching frequencies, so that input impedance of the modules is the same during normal working, thereby realizing power sharing. The method has the advantages of easiness in control, high conversion efficiency of a whole system, high dynamical response speed, high stability and unlimited module quantity.
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Description

technical field

[0001] The invention relates to a switching frequency adjustment method based on current cross feedback, which solves the power sharing control problem of an input-series-output-parallel (ISOP, Input-Series-Output-parallel) modular LLC resonant DC-DC converter, and belongs to power electronics Field of high-voltage DC input application direction. Background technique

[0002] High-voltage input DC-DC converters are now widely used in various industries and products. Although traditional IGBT switch tubes can withstand high withstand voltage, the switching frequency is limited, and it is difficult to improve the dynamic performance of the converter. However, the current common high-voltage MOSFET switch has relatively large on-resistance, weak current passing capability, and difficult selection of device models, which makes the overall efficiency of the converter low and difficult to apply in high-power conversion.

[0003] Modular converters have the advanta...

Examples

Embodiment

[0028] Taking a converter used in a battery charger as an example, its input voltage is 520V to 600V DC, its output voltage is 50V, and its power is 1.25kW. Using input series output parallel two modules LLC resonant DC-DC converter circuit, based on such as figure 1 The circuit shown is realized, and its component module is a full-bridge LLC circuit. In the figure v in is the total input voltage, v o is the total output voltage, Q 1 ~Q 8 It is the switching tube of the primary side of the two modules, and a 400V withstand voltage MOSFET switching tube can be used. D. R1 ~D R4 is the rectifier diode on the secondary side. C i is the input capacitance of each module, C f is the total output capacitance, R o for the total load. L r ,C r , L m are the resonant inductance, resonant capacitor and magnetizing inductance of each module respectively. T r is the transformer, N 1 ,N 2 is the transformer ratio. According to the traditional LLC design method, the resona...