Under the background of carbon emission reduction，fully controlled power device IGBT is widely used in various of converters with its excellent performance，effective and reliable drive circuit is crucial to the safe operation of IGBT，especially for high-power applications. Aiming at the requirement of flexible and reliable of IGBT drive circuit in high-power applications，an IGBT drive and protection circuit based on intelligent integrated optocoupler driver ACPL-332J was designed，the parameters of ACPL-332J were analyzed，and the driving circuit was designed with ACPL-332J as the core. With Infineon FF600R12ME4 as the application IGBT，the effectiveness of the designed drive and protect circuit was verified by double pulse test and short circuit test.

As a new type of compressor，linear compressor has the advantages of high efficiency，small volume，low noise and little vibration. However，in order to give full play to its advantages of high efficiency，it is necessary to control the driving frequency to track its mechanical resonance frequency. According to this characteristic，a frequency tracking control algorithm of linear oscillation motor based on second-order generalized integrator （SOGI） and double correlation phase detection algorithm was proposed. Compared with the frequency tracking control algorithm based on the average value of stroke-current product （ASCP），the control algorithm has the advantages of fast dynamic response and stable operation under variable working conditions，enhances the suppression effect of external interference and improves the stability of the control system. Simulation and experiments show that the proposed control algorithm can quickly track the natural frequency of the motor，which verifies the rationality and effectiveness of the theory.

In high-precision applications，the control accuracy of the servo system is extremely high required. The control precision of the servo system depends largely on the precision of the feedback measurement. Position and speed feedback accuracy can be improved by increasing the absolute accuracy of the encoder，and it is not sensitive to external interference，while the current sampling link is more sensitive to switching noise，which will cause torque fluctuation and reduce the control precision of the servo system. Based on the principle of high-precision current sampling in servo system，the influence of switching noise on current control accuracy was studied. An SINC3 filter structure with continuous output and a method to improve the steady-state current control accuracy were proposed. The experimental results show that the method has obvious effect on restraining the current fluctuation caused by switching noise，and has strong engineering guiding significance.

The motor actuator used in circuit breaker has the advantages of simple structure，small dispersal of action and strong controllability，which provides the possibility for the switch contact of circuit breaker to follow the preset reference curve. The traditional control method can not adjust the parameters according to the movement process of circuit breaker switch contact，and the following is poor，and the intelligent control algorithm is complicated in calculation，affects the rapidity of control system，and is extremely difficult to implement in engineering. A piecewise pseudo-differential control strategy was presented，which avoids direct differentiation of the controlled variables and has the ability of fast dynamic response and anti-interference. Meanwhile，the control system parameters were given according to the segmented environment to ensure the following accuracy. The control strategy model was established for simulation analysis，and the 126 kV circuit breaker motor actuator control system was developed for experimental verification. The simulation and experimental results show the effectiveness of the control strategy.

The process automation control system L2 of an aluminum zinc plating production line was explored.In response to potential production faults on the production line，a process data control module of the process automation control system was provided. Through the analysis of process data，the fault location of the strip steel or production line was analyzed. Finally，a quick method for finding the fault location was provided. The actual operation shows that this method is stable，reliable，and meets the control needs of actual production.

In order to improve the short-circuit breaking capacity of solid-state circuit breaker （SSCB） in DC system，a multi-objective optimization method that explores component parameters to achieve optimal breaking characteristics was proposed. A detailed analysis of the breaking process of the SSCB during a short-circuit fault was performed，and the influence of the current limiting inductor LB and the voltage limiting capacity factor γ of the metal oxide varistor （MOV） on the breaking characteristics was investigated by theoretical analysis and simulation. Based on the breaking characteristics，three optimization objective functions of breaking impact performance，breaking time and energy absorption were established. The objective functions were optimized by the multi-objective particle swarm algorithm，and a method which combines technique for order preference by similarity to ideal solution and decision maker preferences，was used to make decisions. The results show that under different decision maker preferences，the component parameters L_B and γ after the optimization can significantly improve the breaking performance of the SSCB.

Based on full-bridge（FB） and half-bridge（HB） sub-modules（SMs），the conventional hybrid modular multievel converter（MMC） is a typical topology of MMC with DC fault clearing ability. However，the proportion of FB SMs in conventional hybrid MMC is usually greater than 50%，so as to increase the cost and losses. To solve this mentioned issue，a DC fault commutated circuit based on thyristor-switched capacitor（TSC） structure in the hybrid MMC was integrated to reduce the number of FBs，the improved TSC-hybrid MMC was proposed in follows. In TSC-hybrid MMC，HB-MMCs and FB-MMCs were both retained their complete commutated body，and meanwhile，they were connected by a three-winding transformer in AC side and in series with DC side. In particularly，a thyristor-switched capacitor structure was integrated in the DC side of TSC-hybrid MMC to clear the DC fault. According to the analysis，the proportion of FB SMs in TSC-hybrid MMC can be reduced to 10%~25% or even lower （the AC-side voltage quality is a main limiting condition），the cost is reduced as well as the on-state losses. Simulation results validate the correctness of analyses.