During the detection of supraharmonics, noise affects the results, and existing harmonic grouping methods were not entirely suitable for their analysis. Consequently, a supraharmonic detection method based on empirical mode decomposition (EMD)-wavelet thresholding and adaptive grouping aggregation was proposed. Initially, high-frequency intrinsic mode function (IMF) components containing significant noise from the EMD method were denoised using wavelet thresholding. The denoised IMF components were then combined with the original low-frequency IMF components to form the final denoised signal. Subsequently, an appropriate grouping bandwidth was determined based on the switching frequency of the supraharmonic sources, and the supraharmonics within the denoised signal spectrum were grouped and aggregated outward from the characteristic frequency center. Finally, simulation and experiments validated the aforementioned method, indicating the feasibility of the EMD-wavelet thresholding and adaptive grouping aggregation approach for supraharmonic detection.

A hybrid power flow controller (HPFC) combines a phase-shifting transformer (PST) with a voltage source type converter (VSC). The combination of VSC can achieve accurate and continuous regulation of the system power flow, but there are overvoltage problems at the AC bus of the converter under different faults. First, in order to suppress the overvoltage caused by fault, a strategy of adaptive reverse transmission of reactive power to compensate voltage for different overvoltage levels is proposed, and the short-time overvoltage caused by the slow regulation speed of traditional controllers is addressed. An adaptive linear active disturbance rejection control (A-LADRC) method for adaptive adjustment of controller bandwidth parameters is designed and thereby the whole process of HPFC fault overvoltage suppression is realized. Then, the working process and overvoltage mechanism of HPFC are analyzed, the most serious scenarios of HPFC overvoltage are identified, and the related strategies and parameters are designed from the level of control methods. Finally, based on RT-LAB real-time simulator and digital signal processor (DSP) controller, a controller-level hardware-in-the-loop simulation platform is built to verify the effectiveness and superiority of the proposed HPFC overvoltage suppression strategy.

Harmonics and three-phase unbalance are two common forms of disturbances in power systems, which interact with each other and jointly cause more complex impacts on power systems. In order to more comprehensively and accurately analyze the distribution law and interaction mechanism of harmonics and three-phase unbalance, the joint emission level of harmonic and three-phase unbalanced disturbance sources (H-TU-DS) is investigated, and a joint probabilistic emission level modeling method is proposed. First, based on the multivariate correlation coefficients of disturbance source power, harmonic and three-phase unbalanced data, the disturbance source characteristic dataset is screened to realize the data dimensionality reduction. Subsequently, the fuzzy C-means (FCM) algorithm is used to complete the clustering division of the feature data, which lays the foundation for the disturbance source sub-condition analysis. Then, the joint probability model of H-TU-DS is constructed by the nonparametric kernel density estimation method. Finally, the effectiveness and accuracy of the proposed feature dataset screening method, operation condition classification method and joint probability modeling method are proved by comparing and verifying the simulated and measured data.

In order to solve the economic problems caused by the coordinated output of microgrid distributed power generation, an improved jumping spider optimization algorithm (IJSOA) is proposed. First, the best point set strategy is to increase the diversity of the initial population, and the cosine similarity strategy is introduced to enhance the ability to jump out of the local optimal solution, and a non-linear convergence coefficient is set that balances global and local search capabilities, and an improved pheromone update strategy is proposed to accelerate the convergence speed and improve the convergence performance of the algorithm. Then, the grid-connected microgrid economic optimization scheduling model and the optimal operation strategy of the system with the lowest power generation maintenance cost and pollution control cost are established. Finally, simulation experiments are conductes with IJSOA under different strategies, and the results are compared and analyzed with those of other algorithms. The simulation results show that the IJSOA improves the economy by 10.63% compared with the traditional algorithms such as jumping spider optimization algorithm (JSOA) and ant colony algo-rithm (ACO), which verifies the economy and effective-ness of the proposed method.

For the problem of reduced charging performance of wireless charging systems caused by dynamic changes in equivalent load, parameter drift, or system detuning due to factors such as mismatched components, an optimized solution from the perspectives of constant current/voltage charging, system efficiency improvement, and dynamic tuning is proposed. A magnetic flux controllable inductor (MFCI) technology is adopted at the transmitting end to achieve system power control. In contrast, an improved half-controlled rectifier (IHCR) at the receiver end enhances system efficiency and ensures the resonance state. Firstly, the system circuit topology is analyzed to derive equations that show the relationship between key system parameters, charging current/voltage, and system efficiency. The necessity of using a MFCI and an IHCR to enhance system efficiency is explained. Subsequently, these devices are modeled, and their circuit topology and working principles are analyzed. Then, a closed-loop control strategy is analyzed, and the feasibility of the proposed method is verified through PLECS circuit simulation. Finally, a system experimental platform is established, and the experimental results indicate that the designed closed-loop controller can achieve constant current charging (5 A) and constant voltage charging (67.2 V) when the load varies from 9.60 Ω to 134.40 Ω, with a maximum system efficiency of 91.8%.

Collecting parameters such as current and temperature on the motor rotor can effectively prevent rotor side faults and achieve motor vector control better. However, the running rotor rotates at high speed, making it very difficult to provide the signal measured on the rotor side to the controller on the stator side. The electric field coupling wireless signal transmission technology consists of two pairs of axially aligned circular parallel plates forming capacitors, which are installed on both sides of the stator and rotor at the end of the motor. High-frequency and low impedance characteristics of the close-range plate capacitors are utilized to transmit digital signals between the motor stator and rotor, with significantly lower signal delay than other wireless communication technologies. Then modeled the communication circuit, calculated the parameters of each component, analyzed the causes of signal distortion, and the design of a contactless high-frequency signal transmission circuit based on parallel plate coupling capacitors was realized. An experimental platform was built, analog signals from the rotor side were collected and transmitted. By comparing the experimental results, the correctness of communication theory was verified.

Addressing the low carrier ratio characteristics of a dual three-phase permanent magnet synchronous motor during high-speed operation, where traditional deadbeat control fails to ensure adequate current control performance, an improved deadbeat predictive current control method has been proposed. This method incorporates a voltage static error compensator to account for discrete model errors and control delays at low carrier ratios. To address motor parameter mismatch, a discrete sliding mode observer is employed to compensate for voltage disturbance errors. Validation through MATLAB/Simulink simulation and prototype experiments demonstrates that the proposed improved deadbeat current control effectively compensates for motor voltage errors under high-speed operation and resistive-inductive parameter mismatch conditions, offering excellent disturbance rejection and enhancing the system control performance and operational efficiency.

To tackle the challenges of uneven capacitor voltage in the propulsion setup of a three-phase permanent magnet servomotor driven by a T-type three-level inverter, a direct torque control strategy based on zero-sequence voltage injection with carrier modulation is proposed. Firstly, the direct torque control strategy is constructed by motor model calculation. Secondly, the modulation voltage involved in pulse width modulation (PWM) control is obtained by coordinate transformation from the expected voltage, which realizes the combination of carrier modulation and direct torque control. Finally, in order to realize the balanced control of the midpoint potential, the zero-sequence voltage injected is calculated and corrected according to the sampling difference of the upper and lower capacitor voltages. The experimental data demonstrates that the suggested control approach effectively achieves a reduction in torque fluctuations and maintains balanced control of neutral point voltage.

Silicon carbide devices with multi-chip parallel structure are widely used in motor controllers for new energy vehicles in high frequency and high power density applications. The motor controller is a highly coupled electromagnetic-thermal system. The imbalance of chip temperature and stray inductance in the multi-chip parallel structure aggravates the complexity of the coupling system. In order to reveal the deep coupling mechanism of electromagnetic-thermal and the variation law of electromagnetic-thermal domain in the motor controller, multi-physical field coupling analysis under multi-parallel structure is needed. A multi-physical field coupling analysis method based on parameter transfer is proposed. First, the stray inductance model of chip parallel branch at different temperatures is established by magnetic-thermal coupling analysis. Then, through the electro-thermal coupling analysis, the simulation model of silicon carbide chip losses under different temperatures and stray inductance is established. Finally, loss parameter transfer is used to simulate the temperature of the controller under fluid-solid coupling, and the stray inductance model and loss model at this temperature are updated in real time. The electromagnetic-thermal coupling parameters of the chips under the multi-chip parallel structure during the temperature rise of the controller are studied. The accuracy of the multi-physics coupling analysis method is verified by the temperature rise experiment.

Aiming at the problems of high-frequency jitter and phase delay caused by the use of constant sliding mode coefficients, sign functions, and low-pass filters in traditional super twisting sliding mode observer (STSMO), an improved STSMO based on fuzzy control is proposed. Firstly, fuzzy control is used to optimize the constant sliding mode coefficient. Secondly, a new type of continuous function T(s) is used instead of the sign function to reduce jitter, and an Kalman filter is introduced for secondary filtering to further improve the jitter reduction effect. Finally, an enhanced quadrature phase-locked loop (eQPLL) is used to replace the arctangent function to further improve the system and enhance observation accuracy. For time-varying nonlinear permanent magnet synchronous motor (PMSM) control systems, fractional order proportional integral derivative (FOPID) controller can more finely adjust the dynamic response of the system than traditional proportional integral derivative (PID) controller. Therefore, FOPID controller is used to replace the traditional motor speed loop proportional integral (PI) controller. Simulation and experimental results verify that the proposed improved control strategy effectively reduces overshoot, significantly improves the dynamic tracking performance of rotor position and speed, and the improved control system has stronger robustness.