Research On Key Technology Of High Frequency Tunable Reactor And Its Application In Capacitance Detector

This paper comes from the research and development of capacitance aetector,a scientific and technological project.The task of the project is to complete the aging test of large capacity thin film capacitors under high frequency charging and discharging conditions.The project requires the testing frequency range of the capacitance aging system to be 1-30kHz,the capacitance tolerance range to be 1-250uF,and the maximum voltage the system can withstand to be 800V and the current to be 50A.In this paper,LC resonance is used to realize the aging test of capacitor.The control system calculates the inductance required for resonance by obtaining the capacitance value and the test frequency of the tested capacitor,and then controls the adjustable inductor to reach the inductance value to make it resonate.In this paper,the design of high-power adjustable reactor,which is the core work of the project,is studied.In the design process of high-power adjustable reactor,the following two problems are mainly studied:1)the problem of working frequency.The traditional adjustable reactor is mainly used in the field of power system,which belongs to power frequency and has constant frequency.The working frequency in the project is much higher than power frequency and variable.The increase of frequency will produce skin effect and proximity effect for excitation conductor,increase winding loss and reduce high frequency performance of adjustable reactor.2)The adjustment range of inductance value.The regulation times of adjustable reactors under high power are usually only a few times.The regulation range required in this project is about 1,000 times.Traditional adjustable reactors are far from meeting the requirements of the project.In this paper,the inductance of the multi-mutual inductance model with coupling relation is deduced,and mutual inductance coupling,magnetic core stacking,multi-core layered hybrid winding and other methods are comprehensively adopted to improve the frequency performance and regulation performance of the high-power adjustable reactor.Finally,the step-by-step regulation of the contactor is added to make the reactor meet the index requirements of the project.The second part of this paper is the design of capacitance detector system,which mainly includes hardware selection and the programming of graphical control software system at the computer end.The control software is programmed with domestic industrial configuration software force control.The system is driven by SCPI protocol and controls the DC output voltage and current of programmable DC power supply IT6545D.Through Modbus protocol and RS485 bus,communication interaction between computer control software and embedded DSP control board in cabinet is realized.The system also has the functions of viewing and deriving history records and displaying the effective values of voltage and current on the capacitor in real time.The third part of this paper is embedded software programming.Due to the high real-time performance of capacitance detector,this paper proposes a new embedded software system programming architecture.The architecture of the system adopts the idea of layering so as to make the functions of each part of the software clear.In order to solve the problem of global variable management,the concept of database is introduced.By using nested encapsulation of structures to simulate object-oriented programming,the registration mechanism is used to solve the problem of uploading high-speed data.At the end of this paper,the hardware and software of the capacitance detector are jointly tested.The test results show that the system has basically reached the project requirements.