The integration of distributed photovoltaic (PV) power into the direct current (DC) load within 5G base stations can enhance the efficiency of PV utilization and mitigate its adverse impact on the terminal distribution network. Aimed at the issues of poor anti-interference capability in traditional perturb and observe (P&O) methods and the DC bus voltage limit violations caused by PV output fluctuations or changes in load at base stations, a limit maximum power point tracking (LMPPT) algorithm with DC bus voltage sensing capability for 5G base stations is proposed in this paper. On one hand, the algorithm’s anti-interference capability is enhanced by improving the perturbation and observation process of the traditional P&O method. On the other hand, the introduction of a voltage-tiered power limiting control strategy ensures that the DC bus voltage remains within limits, thereby maintaining the safe and stable operation of base station equipment. Additionally, a high-efficiency and high-power-density PV DC combiner module with a rated power of 600 W was built using domestic components, achieving a power density of 135.2 W/in³ and a peak efficiency of 98.9%. Experimental results effectively validated the theoretical analysis and design ideas.

With the continuous promotion of “dual-carbon” goals and the increasing demand for re-electrification development, the construction of new power electronic converters is still one of the research hotspots in the field of power electronics. However, the traditional topology construction method relies on designers’ experience, so the design process is inefficient, and the design method lacks generality. Therefore, the intelligence of topology construction contributes to improving the efficiency and generalization of topology design. A DC-DC converter is taken as an example, first, the process of power electronic converter intelligent construction is divided into three main links, i.e., topology description, topology generation and topology performance analysis. Then, the topology description method, topology construction rules, topology constraints and topology performance indicators suitable for intelligent construction are described in turn. Finally, the realization of topology intelligent construction based on a programmable search algorithm and reinforcement learning is introduced. The research shows that the power electronic converter topology intelligent construction has just started, and there is still a lot of work to be carried out in multi-type topology construction, multi-objective optimization, performance intelligence analysis, etc.

Aimed at the health status of insulated gate bipolar transistors (IGBTs) and the problem of evaluation on their remaining useful life (RUL), the aging parameter of IGBTs was predicted based on an adaptive recurrent neural network (AdaRNN) transfer learning model. First, the failure mechanism of IGBTs was analyzed, and the on-state collector-emitter voltage was selected as the aging parameter to evaluate the health status of IGBTs. Then, an IGBT aging test bench was set up to collect the aging parameter online. Finally, based on the acquired aging parameter, the AdaRNN model was used to predict the IGBT aging parameter. Results show that when the same IGBT aging parameter was used as the training and test sets, the accuracy and speed of prediction results of the traditional time series model and AdaRNN model were similar. When the aging parameters of two sets of different IGBTs were used as the training and test sets, the AdaRNN model can solve the problem of aging parameter difference caused by device difference, and the prediction accuracy was obviously higher than that of the traditional time series model, indicating the strong generalization capability and robustness of the new model.

The insulated gate bipolar transistor (IGBT) is the core component of a photovoltaic (PV) inverter, and its stability and reliability are crucial to the normal operation of the inverter. Therefore, it is important to ensure the safety and stable operation of the power system through the fault diagnosis of a PV grid-connected inverter. Aimed at the single-tube open-circuit fault which is common for the IGBT in a three-phase PV grid-connected two-level inverter, a diagnosis method for the open-circuit fault of IGBT in the three-phase PV grid-connected inverter based on Markov transition field-convolutional neural network (MTF-CNN) is presented. A simulation model of the three-phase PV grid-connected inverter is built on MATLAB/Simulink to simulate the open-circuit fault of several kinds of IGBTs. The output of fault current signal from the inverter is collected as one-dimensional time-domain signal, which is further converted into two-dimensional images by MTF as a 2D-CNN data set for training. Finally, the fault detection and diagnosis are completed. Experimental results show that the proposed method has strong anti-interference capability. In addition, it has a faster diagnosis speed and higher accuracy than other conventional methods.

To address the problems of DC bias and integral drift resulting from the pure integral link in traditional flux observers, a nonlinear flux observer is developed based on the mathematical model of a surface-mounted permanent magnet synchronous motor under the stationary coordinate system. Then, the information about the rotor position and speed is extracted using the phase-locked loop technology. In consideration of the working condition of the aviation pump load, the disturbances caused by nonlinear factors such as frequent changes in load torque and the dead time of an inverter will impact the speed and current regulation performance of position-sensorless control. This further results in increases in the magnetic field orientation error and rotor position estimation error. By combining with the linear active disturbance rejection control technology, a position-sensorless active disturbance rejection control strategy based on a nonlinear flux observer is proposed, which enhances the anti-disturbance capability of the position-sensorless closed-loop system. The effectiveness of the proposed position-sensorless control strategy was verified through a comparison between the simulation and experimental results.

High-speed permanent magnet synchronous motors have characteristics of small stator inductance and high fundamental frequency, and using traditional voltage source inverters to drive them may lead to large stator current ripple and high torque ripple. Variable bus voltage-type inverters can be used to reduce the current ripple, but the traditional variable bus voltage control strategies have numerous parameters and complex calculations. In response to this issue, a relatively simple variable bus current control strategy is proposed, which directly adjusts the DC bus current output from the previous stage to achieve the motor speed control and reduce the stator winding current ripple. Zero d-axis current control is achieved through magnetic field vector amplitude control and phase angle allocation. First, the topology and working mode of a variable bus current-type inverter used were introduced, and the mechanism of reducing the stator winding current ripple by this topology was analyzed. Then, based on this topology, a relatively simple variable bus current control strategy was put forward, and its computational complexity was compared with that under the traditional variable bus voltage control strategy. Under the proposed control strategy, the amplitude and angle of the magnetic field vector were separated, and a control model for the system was established, in which the amplitude control was used to adjust the motor output torque and the angle control was used to achieve motor rotor traction and torque angle control. Finally, the effectiveness of the proposed topology and its control strategy was verified through simulation and experimental results. Specifically, the stable control of a high-speed motor at 80 000 r/min was achieved in the experiment, achieving zero d-axis current control and effectively reducing the stator winding current ripple.

The liquid pump driven by a bearingless permanent magnet slice motor has higher requirements on the motor suspension performance in a complex fluid load environment. Aimed at the problems that the motor model is difficult to obtain accurately and the complex fluid load affects the motor suspension performance, an improved control strategy for the rotor radial suspension performance based on electromagnetic force modeling and disturbance compensation is proposed. First, based on the Maxwell tensor method, an analytical model of rotor radial suspension force including active suspension force component and eccentric magnetic tension component is established. Second, the unmodelled part is observed by a linear extended state observer. Third, from the aspect of compensating the eccentric magnetic tension and compensating the unmodeled part, the suspension winding current is reconstructed, and the corresponding suspension control subsystem is constructed. Finally, the effectiveness of the proposed control strategy was verified by experimental results.

Mine inverters typically operate in enclosed spaces where the thermal-electric coupling effect is significant, leading to thermal degradation and thermal failure. Additionally, mine inverters and motors are often connected by long cables, necessitating a consideration of the high-frequency negative effects of these cables. A 630 kW/1 140 V four-quadrant mine inverter is taken as a research object, its integrated thermal-electric coupling model is established, and its relevant characteristics are analyzed. First, a high-frequency circuit model of the mine inverter is constructed. Second, the mechanism by which the losses of various power devices are affected by temperature is studied, the nonlinear relationship between temperature and some losses is analyzed, and analytical models for losses changing with temperature are derived. Finally, the coupling relationship between the high-frequency circuit model, loss model and temperature field model is analyzed, and the integrated thermal-electric coupling model of the mine inverter is built. The simulation results of coupling demonstrate that it is necessary to perform thermal-electric coupling modeling, and the maximum error between experimental and simulation temperature results is only 0.9 ℃, validating the accuracy of the established model.

At present, the integration of large-scale and high-proportion renewable energy into power grids promotes the quick development of electrochemical energy storage stations. However, safety problems frequently occur at electrochemical energy storage stations, and the inadequate protection equipment for energy storage stations restrict their operation and usage. Therefore, it is necessary to develop the fault identification and protection technology for energy storage stations. First, based on the topology of a real energy storage station, the current superposition method is used to derivecalculation formulas forintra-cluster short-circuit fault and inter-cluster short-circuit fault on the DC side of the energy storage station, and the accuracy of the calculation method is verified through asimulation model. Second, through the analysis of short-circuit current under different fault positions and different numbers of short-circuited battery packs, the changes in current at different positions before and after the occurrence of faults are specified, and a fault diagnosis method forthe energy storage station based on current difference is proposed. Finally, the proposed method is verified by calculation and simulation results, indicating that it can effectively identify the intra-cluster short-circuit fault and inter-cluster short-circuit fault on the DC-side of the energy storage station.

The breakdown voltage characteristics of power devices are primarily determined by the terminal. Variation of lateral doping (VLD) is a commonly used terminal technology, known for its advantages such as low cost, simple process, and high flexibility. In some cases, traditional linear VLD terminals have limitations, particularly in terms of breakdown voltage. A new nonlinear VLD terminal derived from theoretical analysis is presented, which features superior electrical characteristics and more uniform electric field distribution. This effectively weakens the concentration of the electric field and increases the breakdown voltage. In the same process and material conditions, the breakdown voltage peak of the linear VLD structure is 728 V, while the nonlinear VLD structure can weakens 758 V, achieving a 4.12% enhancement in breakdown voltage characteristics. Moreover, the new structure is relatively easy to implement with minimal increase in process complexity.