Research On Local Voltage Sensing Model,Integrated Novel Structure And Its Application Based On IGBTs

Insulated Gate Bipolar Transistor（IGBT）is the core device for power conversion in industrial control,rail transportation and power grid systems.In many scenarios,such as series voltage,online performance optimization,and device health monitoring,the support of IGBT voltage sensing technology is highly needed to meet the requirements of integrated circuits,and effectively ensure that the system works normally and reliably.Therefore,the safety,controllability and linearity of voltage sensing have always been the focus for both academia and the industry.The existing voltage sensing mode is to detect the entire voltage range of power devices.The development of this mode faces limitations.The first is the conflict between sensing safety and signal resolution.Under non-regulated conditions,the sensing signal increases with the increase of the voltage level,resulting in a large dynamic range and safety problems.The signal resolution becomes the prominent problem if the dynamic range of the signal can be reduced to a safe value.Secondly,the flexibility and applicability of existing integrated voltage sensors are questionable,and the designability and controllability of sensing characteristic still need to be further improved.Finally,linearity is an important characteristic of sensors,but academia has yet to provide a solution for reducing nonlinear errors in the design of structures.To address the above bottlenecks,this dissertation provides an in-depth study of new modes and models,new structures and applications for IGBT sensors.A novel Local Voltage Sensing（LVS）mode has been proposed,and a dynamic regulation model has been established.A new integrated device structure has been proposed and experiments have been conducted,and the application methods of LVS mode have been explored.The main innovations are listed as follows:1.A novel IGBT voltage sensing LVS mode and a new structure of integrated devices.Conventional voltage sensing mode is a full-range,single-operating-state mode,and the LVS mode proposed in this dissertation is a local-range,dual-operating-state mode.The collector voltage(V_ce)sensing range is from 0 V to the rated application voltage（V_r）in the conventional sensing mode,while the LVS mode introduces the starting point for the sensed voltage(V_st).The LVS sensor is in the"blocking state"when V_ce<V_st and is in the"voltage sensing state"when V_ce>V_st.This mode focuses on the voltage sensing in the high voltage range,so it can break through the bottleneck of the safety and signal recognizability of sensing in the high-voltage situation.At the same time,in order to address the temperature drift problem of voltage sensing,the idea of function reuse has been proposed.The"blocking state"is reused to provide temperature information,so that the LVS mode combines both voltage sensing and temperature sensing functions.Based on the mode,a new structure of the integrated device is invented,which is characterized by the"gate control of the barrier":the control gate voltage(V_G2)regulates the barrier height to control whether the carriers cross the barrier or not,which determines whether the voltage sensor is in the"blocking state"or in the"voltage sensing state".The universality of the LVS mode is verified with the help of new structures for different types of Si-based and Si C-based devices covering the voltage scale of 600-3300 V,with device and material types including IGBT,VDMOS and Si C MOSFET.2.Modeling of dynamic regulation and device development.The potential and electric field distributions in the controllable barrier region are analyzed in the blocking and voltage sensing states.A dynamic regulation model for barrier height has been established,revealing the dual feedback mechanisms,and obtaining the dynamic regulation of the barrier height with respect to the internal structural parameters（N_a,D,and W）and the external electrical parameters(V_G2 and R_se).The designability and controllability of V_st is realized,and the carrier transport across the potential barrier is transformed from the inherent exponential regulation to an approximate linear regulation mechanism,which reduces the nonlinear error at the voltage sensing stage.Based on the design formulas obtained from this model,the device development is guided.For a 6-inch IGBT process platform,the cell and terminal design,layout design,process flow design and flow chip experiments are carried out.The test results show that the breakdown voltage of the IGBT chip with integrated sensor is greater than 1200 V,the threshold voltage is 4.5-5.5 V,and the on-state voltage drop is less than 2 V.Under the condition of V_G2=0 V,the integrated sensor exhibits V_st=622 V and a nonlinear errorδof3.85%during the second sensing stage.Under the condition of V_G2=-1 V,the values are V_st=707 V andδ=3.42%,which confirm the feasibility of the LVS mode and the controllability of V_st.In the blocking state of LVS mode,as the temperature increases,the sensing voltage approximately linearly increases with a coefficient of change of about 2.3m V/K,indicating its temperature sensing function.3.New approaches to LVS mode device applications.The sensing accuracy of LVS mode devices in applications and the influence of nonlinear errors under sliding mode control are investigated.The utilization efficiency of the sensing range in applications and the control differences of different convergence laws under sliding mode control are investigated.Two new application methods are proposed:in the application of DC bus voltage monitoring,the LVS mode is employed for bus voltage sensing to improve the sensing efficiency and thus obtain better sensing accuracy.Simulation results show that when the bus voltage reference is set to 900 V with 10%amplitude fluctuation,the corresponding LVS sensor voltage changes by 1.8 V,while the conventional sensor voltage changes by 0.32 V.Therefore,LVS mode has higher sensing accuracy.In the application of sliding mode control,using a sliding mode controller to regulate V_G2 can make the sensor output curve converge to the pre-designed sliding mode surface,thereby optimizing the sampling quality of LVS sensors and reducing nonlinear errors.Simulation results show that the overall error of the sliding mode control waveform based on the isochronous convergence law is 0.03 V,the sensing accuracy reach 99.0%,and the overall nonlinear error of the sampling stage can be reduced to 1.01%.