Junction Temperature Control Of IGBT Power Module Based On Variable Switching Frequency

As the wind power converter operating conditions more and more complex,making the reliability of wind power system requirements are getting higher and higher.The fluctuation of the junction temperature of the power device is the main factor causing the device failure rate,and the fluctuation of the device junction temperature changes with the fan output power.Therefore,follow the fan output power changes,real-time adjustment device junction temperature is very necessary.At present,the main junction temperature control methods include external heat dissipation or cooling to adjust the external junction temperature control of the device junction temperature,and to control the power device loss based on the internal junction temperature control.The former is mainly to adjust the device's average junction temperature,the device junction temperature fluctuations in the adjustment effect is poor.Because the switching frequency has great influence on the loss of power device,the internal junction temperature control mode of variable switching frequency is used to realize the adjustment of the junction temperature of the power device in the fan.In order to analyze the influence of switching frequency on IGBT power module loss and junction temperature,this paper firstly analyzes the loss of IGBT power module of three-phase grid-connected inverter.Aiming at the problem that the traditional three-phase inverter power device loss model is limited to the SPWM modulation strategy,and the influence of the device junction temperature on the loss is not enough.This paper deduces the power loss calculation of the three-phase grid-connected inverter under SVPWM modulation The gain of the IGBT power device is calculated by using the curve fitting method according to the parameters of the power device user,and the influence of the switching frequency on the IGBT power module loss is analyzed.The influence of the switching frequency Adjust the junction temperature to provide a theoretical basis.Secondly,because the switching frequency is an important factor affecting the loss of IGBT power module.In order to realize the effective control of the junction temperature of IGBT power module,this paper presents a method of junction temperature control of IGBT power module with real-time switching frequency.By establishing wind power converter The Junction Temperature Prediction Model extracts the variable junction temperature junction temperature control parameters,obtains the function relation between the IGBT current and the switching frequency,and verifies the junction temperature of the IGBT power module by using the variable switching frequency junction temperature control function.The feasibility of the.Then,in order to realize the switching frequency control of three-phase grid-connected inverter in digital circuit,this paper presents a FPGA-based variable switching frequency implementation method,which is based on FPGA's top-down design idea and parallel running characteristics,The entire control module is divided into multiple sub-modules,each sub-module is running independently of each other,through the VHDL language SVPWM algorithm module,Cordic algorithm module,three-phase phase-locked loop and other sub-module logical behavior,and through software simulation module The logic of the algorithm is used to verify the feasibility of the three-phase inverter variable switching frequency under SVPWM modulation.Finally,the three-phase inverter switch junction temperature control experiment platform is built,with DSP as the sampling part,FPGA as the control core,to achieve the output current changes,the device switching frequency changes in contrast.In this paper,the rationality and feasibility of the method of temperature control of changing switch are verified.