IET Power Electronics最新文献

This paper addresses fault-tolerant control (FTC) in a six-phase permanent magnet synchronous motor (PMSM) with a dual stator winding. Each motor phase comprises two windings symmetrically positioned relative to the stator center. To enhance drive reliability, a modular architecture is adopted for both the stator and the drive system. In this design, each stator winding is independently powered by a dedicated single-phase H-bridge inverter, with individual microcontrollers governing the inverters of each phase. To mitigate harmonic distortions in the phase back-EMFs and minimize torque ripple, the study proposes an optimized harmonic current injection method, complemented by quasi-proportional-resonant (QPR) current controllers for precise tracking of harmonic reference currents. In the event of a phase failure, torque oscillations inevitably arise. To suppress these oscillations, a FTC strategy is employed, which eliminates the second-order harmonic components of the electromagnetic torque generated by the remaining healthy windings. The effectiveness of the proposed control system is validated through software simulations under various fault scenario. Additionally, experimental results are provided to corroborate the theoretical framework and simulation outcomes.This paper deals with the control of a specific PMSM that can be used for electric transportation. The design of the motor and drive is completely modular and in each fault scenario, torque can be produced.

The proliferation of power conversion requirements in renewable energy systems and rail transit systems demands LLC resonant converters with enhanced voltage adaptability and efficiency. This review systematically studies three elements in the design progress for LLC resonant converters: (1) modelling methodologies; (2) extended voltage gain range solutions; and (3) efficiency optimization strategies. Existing modelling approaches, including time-domain analysis (TDA), fundamental harmonic approximation (FHA), and hybrid analytical methods, are systematically compared, revealing inherent limitations in predicting parasitic parameter effects and mode transition boundaries under high voltage operation. For voltage gain extension, methods are categorized into topology modifications (e.g., dual bridge architectures, resonant tank morphing) and control-based solutions (e.g., hybrid frequency-pulse width modulation), with detailed analyses of their impacts on component stress and dynamic stability. Efficiency optimization is analysed through three key approaches: light-load efficiency improvement, resonant frequency tracking techniques for loss minimization, and synchronous rectification implementations. By comparing the key parameters with the multi-objective optimization framework, the application boundaries of the existing design methods are summarized, and the current challenges and future development directions in this field are discussed.

Renewable energy stations are often equipped with virtual synchronous generators (VSG) for frequency and voltage support, but the transient instability of VSGs and the weak overcurrent capacity constrain the safe and stable operation of Renewable energy stations. A large number of existing studies have only considered the parameter design and control strategy improvement of VSG itself, which requires high energy storage capacity and control capability of VSG and does not make full use of the existing resources of the Renewable energy station; therefore, this paper considers the synergistic control of static var generator (SVG) and VSG. Firstly, the feasibility of co-regulation between SVG and VSG is analysed from the transient characteristics and current characteristics of VSG. It is proposed that SVG can enhance the transient stability of VSG and reduce the VSG fault current under grid voltage dips. Based on the above analysis, considering the hybrid system's low voltage ride through (LVRT) and fault current limiting requirements, the critical clearing time (CCT) is used to portray the operating range of the hybrid system during faults, and the cooperative control strategy of SVG and VSG during faults is proposed. Finally, in order to solve the current mutation problem in the fault recovery phase, the power angle tracking control is introduced in the VSG active-frequency loop. In summary, the transient stability and current limiting of the hybrid system during the whole process of the fault are realised, and the above theory is verified by simulation and experiment.

In DC microgrids powered by solar systems, the use of ultra-high step-up DC-DC converters is considered an optimal choice, owing to the insufficient voltage provided by the panels and varying environmental conditions. This paper proposes a non-isolated ultra-high step-up DC-DC converter, combining a modified SEPIC structure with a voltage doubler rectifier cell and a two-winding coupled inductor. The proposed converter features high voltage gain, continuous input current with low ripple, low voltage stress on components, and high efficiency. The synchronisation of the turn-on and turn-off times of the MOSFETs in the proposed converter eliminates the need for complex controllers. Additionally, characteristics such as common ground between input and output, which reduces electromagnetic interference (EMI), along with low cost and high power density, enable its suitability for solar systems. An analysis of the proposed converter under steady-state conditions is carried out, and its advantages are assessed through a comparison with other similar structures. Furthermore, its controllability, stability, and dynamic response time are improved by implementing the pole-placement control strategy. Finally, the analysis results are verified with tests on a laboratory prototype of the proposed converter in the power range of 200 W and a switching frequency of 40 kHz.

Pulse power systems and devices represent a specialised area within electrical engineering. These systems are commonly employed in applications requiring substantial energy delivery over a short duration. Operating semiconductor devices under such conditions presents distinct challenges regarding their reliability, as they must endure high instantaneous power levels albeit at low duty cycles of less than 1%. Multiphysics finite element analysis (FEA) has previously been utilised to evaluate packing reliability under standard thermal and cycling power loads. This paper aims to employ FEA to assess the mechanical stress on the wire bond–die interface resulting from the high peak currents specific to these applications. The results and analysis show that pulse power applications apply additional stresses to the wire–bond die interface that have a significant effect on device reliability. A comparison between wire bond and ribbon bond interconnections was completed, showing how this additional stress can be reduced, allowing for more robust devices for pulse power applications.

Virtual synchronous generators (VSGs) based inverters have been widely applied for active frequency and voltage support. However, when the grid encounters unexpected large disturbances, like voltage drops, the power electronic components of the inverters are prone to suffer from overcurrent, resulting in the inverter being disconnected from the grid, and threatening the stability of the power system. To enhance the fault ride-through (FRT) capability for the VSGs, an FRT control method based on dynamic power compensation (DPC) is proposed in this article, which comprehensively considers both the fault current limitation and power angle stability for the VSG. The special phenomenon of injecting reactive power into the grid during faults, resulting in the VSG absorbing active power after voltage recovery, is thoroughly analysed. Then, an improved control strategy is proposed that coordinates the regulation of the VSG's active and reactive current references, effectively avoiding active power backflow. Finally, the feasibility of the proposed method is verified through simulation and experiment.

This paper introduces a full bridge high voltage gain resonant switched capacitor converter (SCC) providing soft switching conditions for all power semiconductors above and below the resonant frequencies. The proposed unidirectional converter operates effectively both above and below the resonant frequencies, which extends its practical range of applications. Its output voltage can be regulated by different methods such as phase-shift, PWM and frequency modulation techniques. Frequency modulation enables output voltage regulation across a wide input voltage and load range with minimal switching frequency variation. Symmetrical structure, small input-output filters, compact passive components, low switching losses and reduced EMI noise, input-output common ground, simple control circuit and high voltage gain make the proposed converter suitable for various applications. In addition, the state space trajectory, mathematical analysis, design approach and simulation results of the converter are described in detail, which are also verified by implementing a 60–120 V to 400 V, 200–1370 W prototype converter in practice.

This paper implements low-cost GaN-based three-phase voltage and current sources to validate power protecting relays. This proposal develops a voltage generator that uses three single-phase full-bridge converters equipped with an LC filter and an isolating transformer. It also includes a current generator using three single-phase half-bridge converters furnished with an LCL filter. Both voltage and current testing sources are assembled employing GaN transistor technology, which enables operation at high switching frequencies and passive filters with low-value components. Experimental tests are conducted to confirm and validate the operation and dynamic performance of voltage and current testing sources. Finally, the performance of the voltage and current signal generator is assessed by testing a commercial protection system (SEL-451) through directional current function. This is achieved by emulating a fault condition, where three voltage and current signals are generated to trigger the trip signal after surpassing the relay threshold.

This paper presents a novel topology for a non-isolated bidirectional DC–DC converter designed to operate under soft switching conditions. The proposed converter is developed by incorporating an additional inductor and two switches into the conventional bidirectional DC–DC converter. This modification enables soft switching in both buck and boost operation modes, improving overall efficiency. The added components not only provide additional control parameters but also contribute to power transfer, particularly under full-load conditions. Theoretical analysis of both boost and buck modes demonstrates the achievement of zero-voltage switching (ZVS) operation. To validate the theoretical findings, a 100 W prototype operating at 100 kHz is implemented, confirming the converter's effectiveness.