To improve the degree of intelligence of a substation and cut down the cost of inspection, substation inspection robots instead of the human labor are employed to perform daily inspections. However, the battery life greatly limits the work of inspection robots, so the full-time inspection cannot be realized. To solve this problem, a dynamic wireless charging method is used to charge the robots, so that the robots can perform inspections while charging and realize full-time inspection. In this paper, the relationship between coil mutual inductance and system efficiency is analyzed at first. Then, aimed at the segmented primary coil rails used in the dynamic wireless charging system, a soft-switching method for rails is put forward to reduce the inrush current during the switching process, thus protecting the circuit components. Finally, the influence of coil mutual inductance on the system efficiency was verified by experimental results, and the feasibility and effectiveness of the soft-switching method for rails was also proved.

For a traditional Boost power factor correction (PFC) converter, its output voltage must be greater than its input voltage, which limits its applications in light emitting diode (LED) drivers to a certain degree. Meanwhile, due to the existence of a rectifier bridge at the input end of the traditional LED driver, the improvement of its efficiency is also confined. In this paper, a bridgeless Boost LED driver based on passive current balancing is proposed, which is based on the topology of a resonant Boost PFC converter. With the introduction of a resonant capacitive current-balancing network, the output current of each LED string can be balanced. In addition, the elimination of the rectifier bridge further improves the system efficiency. Finally, a 140 W prototype with a peak efficiency of 93.64% was built, and experimental results verified the correctness and feasibility of theoretical analysis.

A soft-switching DC-DC converter with low current ripple and high gain is proposed, which can be applied to new energy generation systems. Based on the conventional interleaved Boost converter, the proposed converter can achieve high gain by introducing a coupled inductor, diodes and a capacitor Boost unit. The coupled inductor transmits energy during the entire switching cycle, thus improving the utilization rate of magnetic core. The input Boost stage works in an interleaved mode, and the current ripple of the two-phase inductor can cancel each other, so as to obtain a lower input current ripple. Due to the existence of leakage inductance of the coupled inductor, the reverse recovery problem of rectifier diodes are alleviated. Meanwhile, an active clamp circuit is adopted to absorb the leakage inductance energy, thereby achieving the zero-voltage soft-switching of all switches, restraining the turn-off voltage spike of switches, and improving the converter's conversion efficiency. The working principle, circuit characteristics and soft-switching realization method of the converter are analyzed in detail. Finally, a 200 W experimental prototype was built to verify the theoretical analysis.

Aimed at the poor voltage regulation performance and large circulating current of the traditional frequency-controlled LLC resonant converter in wide voltage applications, a six-switch dual-resonant LLC converter is designed, which is a hybrid combination of two full-bridge LLC resonant converters sharing one bridge arm. Compared with the traditional frequency control, fixed-frequency phase-shift control is employed in this converter to adjust the output voltage and reduce the switching frequency range. According to different connection modes of two transformers, the converter has two topological forms. When the two transformers are connected in series in the forward polarity, the converter's gain range is 0-1, which can achieve an ultra-wide output voltage range. When the two transformers are connected in series in the reverse polarity, the gain range is 1-2, and the circulating current loss during the working process is small. Under the two topological forms, the ZVS turn-ON of the primary switch tube and ZCS turn-OFF of the secondary diodes can be achieved, respectively. Finally, the validity of the research in this paper was verified by Simulink simulations and experimental results.

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.

A three-phase Vienna rectifier is taken as the research object in this paper. In view of the difficulty in selecting the weight factor when the finite control set model predictive control realizes the neutral-point potential balance control, as well as the problem of large current ripple on grid-side caused by the action of one single vector during the sampling period, an unweighted factor model predictive control strategy based on double vectors is proposed. First, a single-objective cost function based on power prediction is constructed, and the efficiency of single optimization is improved by sector division and unweighted factor. According to the fluctuation of neutral-point potential on DC side, the redundant small vector is selected to realize the unweighted factor neutral-point potential balance control. Then, based on the obtained optimal vector, the double-vector fixed switching frequency control is realized by combining with the zero vector. Finally, the proposed control strategy is verified on a hardware-in-the-loop platform based on RT-LAB from the aspects of steady state, transient state and neutral-point potential fluctuation, and results effectively prove its correctness and effectiveness.

Aimed at the particularity of an isolated DC/DC converter when it is applied in a space radiation environment, the isolated magnetic feedback circuit is usually used to improve the feedback accuracy and stability. The working principles for several commonly used amplitude modulation magnetic feedback circuits are introduced, and a forward-flyback amplitude modulation bidirectional magnetic feedback circuit is introduced and optimized to solve the problem of the need for an additional secondary power supply voltage. Under the premise of realizing the same function, a two-winding transformer is used to replace the three-winding transformer, which effectively reduces the volume of the magnetic core and simplifies the circuit structure. The working principle for the circuit and the design method for a pulse sampling circuit and a magnetic feedback transformer are analyzed in detail. In addition, based on the magnetic feedback circuit, a DC/DC converter prototype with 100 W output was built. Simulation and experimental results show the effectiveness of the proposed isolated magnetic feedback circuit, providing a theoretical guidance for engineering design.

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.

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.

The conventional Buck-type power factor correction (PFC) converter has a disadvantage of high harmonic current, which limits its applications. A Buck-type single-switch integrated PFC converter is proposed and analyzed. This converter is composed of a Buck-type PFC converter and a Buck-Boost PFC converter, and they are integrated by only one active switch, thereby simplifying the control. Under the constant on time (COT) control, the dead zone of input current in the Buck-type PFC converter is eliminated. With advantages of Buck and Buck-Boost converters, this converter can achieve a high power factor and a high efficiency in universal-input applications. The circuit structure, working principle, steady-state characteristics and design considerations of the proposed converter are introduced and analyzed. Finally, a 56 W prototype was built, and experimental results verified the analysis results.