IET Power Electronics最新文献

This article presents an improved position sensor fault-tolerant control (IPS-FTC) of the stator current components of the permanent magnet synchronous generator (PMSG). It ensures the generator's operation in post-fault conditions, which are required for uninterruptible power injection by renewable energy conversion systems (RECSs). The proposed method is based on sliding mode (SM) theory and overcomes the drawbacks of traditional position sensor fault-tolerant control (PFTC) methods. The developed approach is relatively simple, direct, and robust versus non-modelled quantities. Furthermore, it does not require stator voltage sensors, compared to other developed SM control techniques. The stability and convergence of the proposed approach are proven by simulation and experimental results.

As electric forklifts advance, the electric machine-pump/motor control system is key to their lifting system due to high efficiency. Traditional systems struggle with quadrant switching in permanent magnet synchronous machines and pump coupling, causing flow fluctuations, pressure shocks and load-affected actuator response. This is due to electric machine control issues like speed overshoot, torque shock and varying speed response with inertia and load. In this paper, an improved multiple capacity process—proportional integral derivative electric machine speed smoothing algorithm for stable transitions during quadrant switching is proposed. Also, a generalized fast sliding mode load observer with inertia identification is designed to compensate for torque shocks from unknown loads and enhance speed response robustness. The test bench is built. Experiments are carried out. The results show the proposed method reduces overshoot by 20% compared to the traditional multiple capacity process, achieves zero speed overshoot and improves response speed to 0.6 s (an 80% enhancement). It also minimizes load observer overshoot, reduces inertia identification error and significantly improves speed response robustness, promoting reliable operation of the electric forklift lifting system.

This paper introduces a new switched‑inductor Z‑source inverter topology that employs a capacitor‑assisted inductor network, achieving a significantly higher voltage‑gain factor while simultaneously reducing capacitor voltage stress over an extended duty‑cycle range compared with existing Z‑source inverters. As the diode is replaced with a capacitor, this inverter is converted into a switched capacitor configuration, which increases the voltage gain. The operational principles, steady-state analysis and design of passive elements, analysing the capacitor's voltage ripple and the inductor's current ripple, are conducted. Moreover, various n modes can be extended by the proposed topology, allowing significantly higher gains to be achieved. In addition, a detailed analysis of power loss is conducted on the analysed topology in terms of its efficiency. The accuracy and effectiveness of the proposed inverter are validated through both simulation and experimental findings.

The dual active bridge (DAB) converter is an important interface in power conversion for modern power systems, and it is essential to ensure its efficient and reliable operation. In conventional phase shift control, the change in transmission power is not intuitive, and transient dc bias is inevitable, which leads to complex mathematical calculations and additional dc bias control. To address this, an intrinsic dc-bias-free control framework is proposed in this paper. Based on the variations in inductor energy and power transmission characteristics, the durations of different inductor voltages are utilized to control power transmission, making transmission power variation more intuitive and physically insightful. Efficient switching sequences with inherently zero initial currents are constructed, and the closed-form solutions can be simply derived. The proposed control strategy achieves low computational burden and simple gating logic, inherently avoiding transient dc bias and without duty cycle loss. It can realize full-range power transmission with seamless switching sequence transition. Finally, experimental results confirm the feasibility of the proposed control strategy.

This paper introduces a soft-switching single-switch step-down LED driver. The switch operates under zero voltage switching condition, which eliminates switching losses as well as capacitive turn-on losses. The ZVS operation of the switch is maintained over a range of output current and voltage variations, which effectively enhances the overall efficiency. A load-independent output current is achieved in this structure with the proposed design, which allows the LED driver to operate without requiring an output current sensing and feedback loop, reducing the complexity of the converter. Additionally, the parallel resonant tank effectively reduces the voltage stress across the switch. Moreover, the leakage inductance of the transformer is absorbed into the series tank inductor and acts as a resonant component so that the leakage energy is recycled to the output. Finally, a prototype is implemented to supply a 50 W/30 V LED module at the switching frequency of 200 kHz from 150 V DC input, and experimental results are presented to validate the theoretical analysis. The efficiency of 95.3% is achieved using a low-cost MOSFET switch.

The position self-calibration strategy is beneficial in decreasing the position deviation of the resolver-to-digital conversion (RDC), thereby improving the pointing accuracy of the servo system applied to the satellite optical payload. However, existing self-calibration methods primarily focus on the second harmonic caused by a single non-ideal factor, neglecting the fundamental and higher order harmonics in the typical position deviation resulting from the coupling of multiple factors. To address this issue, an improved position self-calibration method based on multi-harmonics estimation for the RDC is proposed in this paper. First, the position deviation model under multi-factors coupling is established. Second, the speed deviation caused by the position deviation and its integral signal is estimated by the speed observer. The integral signal is input into the multi-harmonics observer, simultaneously estimating the DC, fundamental and higher-order harmonics components, while also analysing the convergence conditions of the observers. Finally, the position deviation is estimated by combining the estimations of harmonics, and the compensation lookup table of the position deviation is established. Simulation and experimental results show that the calibrated deviation is reduced by 89.4% relative to the original deviation. Compared with a comparable method, the proposed method improves calibration accuracy by 27%.

The all-electric aircraft with a distributed electric propulsion system being studied in this article uses 11 motors, of which 10 are specifically used for lift enhancement during takeoff and landing. This paper describes the iterative design method of the open reference prototype of the high-lift motor, including electromagnetic design, support design, and verification of temperature, static load, and rotor dynamics. Firstly, the evolutionary algorithm based on the approximate model is used to optimize the multi-objective in the electromagnetic design process. Under the premise of satisfying the aerodynamic characteristics, the permanent magnet mass and torque ripple are reduced; Secondly, a general analytical model of the Halbach array permanent magnet synchronous motor was established, and the power density of the motor was further improved by parameter optimization; Thirdly, in the design of support components, the influence of static load on bearing selection and shaft design is analysed, and resonance was avoided by vibration frequency, critical speed and modal analysis. Finally, the no-load, rated load, temperature, static load, and pulling test were verified by finite element model simulation and prototype.

Permanent magnet synchronous motor (PMSM) drives with reduced DC-link capacitance face challenges such as increased torque ripple and poor dynamic performance due to low-frequency harmonic distortions. This article proposes a novel control strategy for reduced capacitance PMSM (RC-PMSM) drives that analyses dominant oscillation components and formulates an optimization problem to compute optimal harmonic current injection while minimizing motor losses. The optimized harmonics are injected into the motor currents to effectively mitigate torque fluctuations. Simulation results demonstrate that the proposed method achieves a torque ripple reduction of up to 54% at 2000 rpm with a 68 µF capacitor, alongside a significant suppression of speed oscillations and an improvement in current THD. These enhancements significantly improve motor performance and stability, offering a practical and efficient solution for optimizing RC-PMSM drives in various industrial applications.

This paper proposes an improved robust predictive current control strategy, combining an improved ultralocal model with a hybrid space vector modulation (HSVM) scheme. Compared to conventional ultralocal model, the proposed improved ultralocal incorporates grid voltage dynamics into the model architecture and replaces online estimations with direct sampled-value. The proposed control strategy enhances tracking accuracy during grid voltage fluctuations, especially under unbalanced and harmonically distorted conditions. Additionally, the HSVM strategy dynamically switches between three voltage vector sequences according to modulation index thresholds, which improves steady-state performance in non-ideal grid conditions. To address the prevalent issues of voltage fluctuations and harmonic distortion in practical power grids, existing solutions inject compensation into the complex power reference. However, existing methods overlook the negative-sequence current effects, which may lead to inaccurate results under unbalanced conditions. This paper incorporates the effects of negative-sequence currents and derives the power compensation term under non-ideal grid conditions, yielding an accurate analytical expression. Experimental results demonstrate that the proposed method exhibits strong robustness against inductance parameter variations and reduces current THD by 26% (ideal grid) and 11% (non-ideal grid) compared to conventional methods.

To monitor the operating status and fault behaviour of power modules, this paper proposes a 6.5 kV/100 A silicon carbide (SiC) MOSFET power module capable of monitoring the drain currents of parallel-connected chips. The design combines three key innovations: (1) A structure and integration method for a four-channel printed circuit board (PCB) Rogowski coil used in high-voltage SiC power modules is proposed, exhibiting excellent anti-interference; (2) To reduce both the total module parasitic inductance and package-induced inductance imbalance, a symmetrical layout with pin-type terminals was proposed. (3) A field control method for the 6.5 kV power module is proposed, based on adjusting ceramic thickness and copper layer spacing at the triple junction. The module was fabricated to validate the effectiveness of these innovations. Under 15 kV DC and 50 Hz square-wave voltage conditions, no repetitive partial discharge exceeding 10 pC or leakage current above 1 µA was observed. The power loop parasitic inductance was measured as approximately 14.94 nH using an impedance analyser. Finally, the static and dynamic characteristics of the module were validated through static parameter analysis and double-pulse testing. The integrated PCB Rogowski coils monitored the drain current through each chip during double-pulse tests, showing good agreement with measurements from the commercial high-bandwidth Pearson coil.