Research On High Voltage Isolated Resonant DC-DC Converter For TWT

Space TWT amplifier is the important part of satellite payloads for signal reception and amplification.In process of TWT power manufacture for more than 50 years,TWT has improved its power supply module standards while improving its performance.In order to increase power and reduce module size,progress of TWT power supplies are generally towards highly efficient,small size,light weight,and high power.According to literature reviewing,research on TWT power supply has been focused on the design of topologies in recent years.Therefore,this study will use high-voltage topologies with high efficiency and high stability as initial standards of TWT power supply design.Design of TWT power module uses a Buck-LCLC two-level topology.Compared with a single-level topology,the two-stage topology can effectively stabilize the voltage at the input side.At the same time,the Buck converter as a mature structure has a relatively stable output characteristic.On the other hand,in order to obtain an output voltage up to 10,000 volts,the actual circuit needs to use a high voltage transformer to complete the voltage boost mission,but due to the non-negligible parasitic parameters brought by the high boost ratio,a resonant topology is needed to deal with it.Compared with different resonant topologies,the LCLC topology effectively combines the transformer parasitic parameters with the resonant mechanism to achieve zero-voltage switching(ZVS),zero-current switching(ZCS),and naturally turned off for secondary-side diodes.So,the LCLC resonant converter can operate achieve high efficiency under high switching frequency.In the design of the regulator,it is necessary to use a stable voltage as the sampling point,though high-voltage output side has the fixed voltage value,auxiliary circuits should be accounted and single class of output voltage cannot reflect the other sides under load changing,therefore,it will be uneasy to make simple on high-voltage compare with Buck output side.For the compensation design,wave approximation method is used to model small-signal LCLC resonant converters.Thevenin and Norton theorem are used to convert seven-order small-signal model into third-order transfer function.In addition,choose linear voltage stabilized circuit as power management method to restrain voltage drift which is easily happen under idle load.Using Matlab and Saber simulation software to verify the accuracy of smallsignal model and feasibility of voltage regulation.The influence caused by different parasitic parameters of the high-voltage transformer on the post-stage resonant converter is analyzed base on small-signal model.The matching method of the transformer winding is given for the calculated parameters.The adjustment scheme is given according to the measured transformer parameters.To meet the indicators of the spacecraft power supply,protection circuit is also design.The experimental board was built and the theoretical analysis is verified based on the measured data.According to the experimental results,the comparison and verification are used to analyze the advantage of the LCLC resonant converter as a post-stage topology in terms of load stability and efficiency.