The Study Of 660V/127V Power Electronic Transformer In Coal Mine Based On TMS320F28335

In the power supply modules such as downhole lighting systems,comprehensive protection devices,and hand-held electrical equipment,the traditional dry-type transformers used are in large volume,heavy weight,and poor controllability;therefore,This paper proposes the use of power electronic transformers instead of dry power frequency transformers.Compared with traditional power frequency transformers,power electronic transformers not only have functions such as voltage conversion and electrical isolation,but also have the advantages of small size,small weight,good controllability,and the ability to realize fault isolation,etc.and have the ability to solve downhole lighting power systems and comprehensive protection.And there are the potential of many new problems in power modules such as devices and handheld electrical equipment and it is of great research value.The paper analyzes the research background and research significance of power electronic transformers,compares and analyzes the advantages of power electronic transformers,analyzes the basic theory,development history and research status of power electronic transformers,and analyzes the working principle of power electronic transformers and the two typical implementation,analysis shows that the AC/DC/AC type power electronic transformer has advantages such as strong controllability and good fault isolation effect;the mathematical model analysis and parameters calculations of the designed AC-DC-AC power electronic transformer are performed.The circuit analysis was performed on the input,intermediate and output links of power electronic transformers.Two commonly used control methods for isolation and output were analyzed.The control method for intermediate links was designed as open-loop PWM control.The control method is designed as a double closed-loop control method based on the output phase voltage effective value and instantaneous value,and the control algorithm is analyzed theoretically.Matlab/Simulink simulation software is used to simulate the three steps of the power electronic transformer topology and the overall circuit.The results show that: the input link can output a stable high-voltage DC voltage;the intermediate isolation link can achieve voltage conversion,output stable low-voltage DC Voltage;The output stage can output a stable three-phase AC voltage with a sinusoidal waveform;the simulation results of the overall circuit of the power electronic transformer show that when the system is connected to a symmetric resistive load,the load is suddenly changed,and a symmetric impedance inductive load is connected,it can output a stable 127 V three-phase AC voltage with better sine wave shape.The IGBT module is subjected to principle analysis and type selection.The IGBT modules in the intermediate and output stages are selected as IKW25T120 and IGP50N60T.Then the driving circuit of the IGBT module is designed.The working principle and working process of the IGBT module are analyzed in detail.IGBT module protection and buffer circuit are designed.The overall hardware structure of the power electronic transformer control system is designed;the controller selection design is TMS320F28335,and the system hardware circuits such as control circuit,drive circuit,power circuit,conditioning circuit and power supply circuit are designed;the voltage hall sensors are selected as LV-25-200 and LV-25-400 respectively,the terminal wiring circuits of the voltage sensors are designed.The software part of the control system is designed,mainly including the control system main program,initialization subroutine and closed-loop control algorithm subroutines.The control algorithm is programmed by software,and the experiment verifies that the control algorithm can output a better control signal waveform.