A flux-weakening control method for permanent magnet synchronous motor (PMSM) used in electric vehicles is put forward on the basis of current prediction to improve the dynamic performance in the flux-weakening region of PMSM. The voltage boundary problem in the flux-weakening region is analyzed in detail, and the stability problem under different voltage selection criteria is also introduced. On this basis, a dynamic overmodulation strategy considering the stability and dynamic characteristics is proposed. Furthermore, a model-based predictive current control algorithm is investigated, in which the advantages of fast dynamic response and manageable constraints help to improve the dynamic performance in the flux-weakening region while guaranteeing the stability. Finally, the effectiveness of the proposed algorithm was verified on a simulation platform and an experimental platform, respectively.

Silicon carbide (SiC) switching devices are widely applied in DC/DC converters owing to their faster switching speed and higher operating frequency. However, the high working frequency of SiC devices will result in strong electromagnetic radiation interference. To optimize the internal structure of DC/DC converter and achieve a higher power density, an optimization method for the electromagnetic radiation interference of SiC DC/DC converter is proposed. First, the characteristics of the converter's electromagnetic radiation interference source are analyzed, and a space electromagnetic radiation model is established according to the topology of DC/DC circuit. Then, based on the electromagnetic radiation model and simulated annealing algorithm, the low electromagnetic radiation optimization is carried out for the layout of components within the DC/DC converter. The optimized layout scheme reduces the length of high-frequency wire by 60.2%. Finally, the three-dimensional finite element simulation is carried out, and it is verified that the proposed method can optimize the circuit layout of SiC DC/DC converter and reduce the electric field intensity produced on the sensitive circuit by two orders of magnitude.

Monitoring the power quality of power supply system is an effective method for ensuring the safe operation of power system and user-side equipment. To ensure the power quality of power supply system, a monitoring method for its power quality stability is studied. Based on the Hilbert-Huang transform (HHT) algorithm, the harmonic frequency and amplitude of the power quality signal frame of power supply system are monitored, and the disturbance time amplitude and frequency of the power quality disturbance signal are detected, so as to realize the power quality stability of monitoring system. The frame loss rate, accuracy and transmission delay of the monitored power quality signals under different pressures (with different numbers of power quality signal frames) were tested by experiments, and results show that the proposed method can realize the monitoring of power quality.

The silicon carbide (SiC) device is considered as a semiconductor device with high temperature resistance, and a careful study on its loss and heat dissipation is required when it is applied to high-power-density and high-temperature scenarios. The maximum current conduction capability of SiC MOSFET power module at high temperature is studied, and the relationship between electrical performance and heat dissipation is taken into account. Based on an electro-thermal coupling model of SiC MOSFET device and a heat dissipation model of the cooling system, the mechanism of thermal runaway process is analyzed. A co-simulation is conducted to determine the current conduction capability of one SiC power module at high temperature, and the simulation error with respect to the experimental result is about 4%, which verifies the effectiveness of the proposed method.

The parameter identification method for the equivalent circuit model of lithium-ion battery has a great impact on the model accuracy. To solve the problems of low convergence accuracy and slow convergence speed in a satin bowerbird optimization(SBO) algorithm, an improved satin bowerbird optimization (ISBO) algorithm is proposed. The inertial weights, Cauchy mutation, Gaussian mutation and greedy selection strategies are used to improve the convergence accuracy of the ISBO algorithm, and its convergence performance is verified by standard test functions. Based on the battery charging and discharging data, the proposed ISBO algorithm is applied to the parameter identification of the equivalent circuit model of lithium-ion battery. Experimental results show that compared with the SBO and adaptive weight particle swarm optimization algorithms, the ISBO algorithm has a higher accuracy when it is used in identifying the model parameters and the identification accuracy is not affected by the working conditions of battery.

The integrated control of frequency transient stability of multi-microinverter microgrid is studied, which can effectively control the frequency transient stability of microgrid, improve the control accuracy, and shorten the regulation time. By means of excitation control and power frequency control, a virtual synchronous generator(VSG) control method is constructed to realize the frequency transient stability control of microgrid under a small load disturbance. The improved droop control method is used to realize the frequency transient stability control of microgrid under a large load disturbance. By designing a synchronous voltage controller and a double-loop controller, the free switch between the VSG control method and the improved droop control method is completed, and the transient stability of microgrid frequency under different conditions is controlled comprehensively. Experimental results show that the proposed method can effectively control the frequency transient stability of microgrid under different load disturbances. When switching between the off-grid and grid-connected modes, the control methods are effectively switched, the frequency transient stability of microgrid is accurately controlled, and the regulation time is shortened.

In this paper, the modulation scheme for a dual active bridge (DAB) bidirectional DC/DC converter is studied. The main advantage of the DAB converter is that it has characteristics such as symmetrical structure, bidirectional power flow capability, wide soft switching range and flexible control capability. The simplest way to control this topology is to control the direction and magnitude of power transmission by adjusting the phase shift angle between the primary and secondary bridges. However, when the input or output voltage of the converter varies widely, a large amount of reactive power will be generated under light load conditions. Meanwhile, the zero voltage switching (ZVS) operation of part of switches cannot be maintained, which directly leads to a low conversion efficiency. Therefore, to improve the efficiency of the DAB converter, a hybrid phase shift modulation (PSM) scheme is proposed, which can reduce the inductor root-mean-square (RMS) current and extend the soft switching range on the basis of keeping the control simple, thereby improving the performance of the converter. First, by making the controllable variables in the extended phase shift(EPS), dual phase shift (DPS) and triple phase shift (TPS) modulation schemes equal, four different PSM schemes are obtained. Then, the steady-state characteristics of these modulation schemes are compared and analyzed, including their transmission power capacity, inductor current level and soft switching performance. On this basis, a hybrid PSM scheme is formulated. Finally, an experimental platform was built to verify the effectiveness and correctness of the proposed modulation scheme.

A Super-Boost converter can greatly reduce the mass and volume of power supply and improve the corresponding power density by replacing the traditional charging and discharging module, so it has a broad application prospect in space power system. However, due to the existence of multiple power components and the reverse flow characteristics of inductance current, its power supply mode and output ripple voltage are more complex than those of the traditional Boost converter. To provide a theoretical guidance for the analysis and design of the Super-Boost converter, its power supply mode and output ripple voltage are studied. It is found that there exists continuous conduction mode, pseudo continuous conduction mode and pseudo discontinuous conduction mode in both inductor L₁ and L2. The analytical mathematical models of critical inductance and output ripple voltage in each operation mode are established, the relationship between peak current and inductance is discussed, and the minimum capacitance and minimum inductance that meet the design requirements are obtained. On this basis, a design method for the converter parameters is given, and experimental results verify the theoretical analysis.

The problem of high-order nonlinearity in the transient process of a wireless power transmission system is a difficulty in load measurement and identification. When dealing with beat-frequency signals due to the high-order nonlinearity, there are some problems in the existing analog envelope detection method, such as signal distortion, poor circuit flexibility, and limited measurement range. Aimed at these problems, a digital envelope detection method was proposed based on Hilbert transform, and a digital envelope detector was designed to extract the envelope of the voltage beat-frequency signal. In addition, simulations and experiments were conducted to validate the proposed method. Results show that this method can accurately extract the envelope of the voltage beat-frequency signal with different loads, and it achieved an error of less than 5% in the load resistance range of 1-2 000 Ω. The proposed method extends the contactless load measurement range based on characteristic parameters in the transient process, providing a new idea for measuring the internal resistance of batteries in aircraft such as unmanned aerial vehicles.

To accurately obtain the on-orbit health status of a spacecraft electrical power system, a condition quantitative assessment model for a satellite electrical power system with the fuzzy theory is proposed. First, an index system for evaluating the system condition is established by analyzing the operating characteristics of one satellite electrical power system. Combined with the time-varying characteristics of actual telemetry, the corresponding telemetry pre-processing method for electrical power system and a dimensionless deterioration function are put forward. Then, a hierarchical condition quantitative assessment method for the satellite electrical power system is established through introducing the variable weight theory and fuzzy theory. Finally, the correctness and effectiveness of the proposed condition quantitative assessment method are verified by analyzing the actual on-orbit and simulation data of the satellite and comparing with the traditional method. Moreover, the deteriorated system condition can be assessed by the proposed method two days earlier only based on thresholds.