IET Power Electronics最新文献

An accurate simulation model can guide applications such as loss estimation and key parameter evaluation for power devices. Existing SPICE-compatible models suffer from compromised accuracy-efficiency trade-offs, inadequate characterization of temperature effects, and convergence limitations. To address the limitations of conventional behavioural models, which often require numerous parameters and exhibit poor extrapolation capability, this paper proposes a novel behavioural model utilizing a tanh(x)-based channel current expression. This formulation not only inherently ensures smoothness and continuous differentiability, mitigating convergence issues, but also significantly reduces the number of core characterization parameters to just five. A stepwise parameter extraction method is given via Levenberg–Marquardt optimization to effectively prevent overfitting-induced spurious points in the output characteristics during multiparameter fitting. Recognizing the critical impact of temperature on SiC MOSFET performance, temperature effects are embedded through second-order polynomial fittings across the full operational range. In the meantime, temperature effects on critical parameters during switching transients are considered through theoretical analysis. Experimental validation via double-pulse tests across a wide temperature range confirms the model's high fidelity, with static characteristics deviation below 3%, switching loss error within 8%, and transient oscillation discrepancy under 2%, demonstrating its value for precise simulation in SiC-based converter design.

This article features a comprehensive methodology for analyzing and optimizing PWM dead time in automotive traction inverters, applicable to a wide range of power devices, including Si IGBT/Diodes, SiC MOSFETs, and Si/SiC Fusion switches. The proposed methodology enables a systematic comparison of dead time characteristics, focusing on part-to-part tolerances and operating point-dependent influence factors. Three traction inverter systems, each in the 200–300 kW class at 470 V, were built up utilizing Si IGBT/Diode, SiC MOSFET, and Si/SiC Fusion switches from the latest automotive-released technology. The impact of PWM dead times on power losses was experimentally investigated for all three inverter systems, supporting the analytical model. Key findings from the experimental data include: (1) PWM dead times can account for more than 10% of the total inverter power losses in high current density SiC MOSFET inverter designs operating at typical automotive switching frequencies of 10 kHz; (2) Optimizing PWM dead times in Si/SiC Fusion power modules leads to up to a 5% reduction in total inverter power losses and improved current sharing, resulting in lower thermal stress—This was evaluated using thermal infrared measurements from the Si/SiC Fusion inverter prototype; 3) Optimized PWM dead times can reduce total harmonic distortion at light load conditions by up to 2%–3% for IGBT/Diode and up to 4%–5% for SiC MOSFET and Si/SiC Fusion inverter systems; (4) A sensitivity study in addition revealed that Si/SiC Fusion switches exhibit the most stable dead time settings under parameter variations. The benefit of optimized versus conventional 2 $��\mu �s�$ PWM dead times would result in an annual energy saving of approximately 6 GWh per 1 million vehicles. This highlights the significance of optimized PWM dead times in automotive traction inverters operating at typical switching frequencies of 10 kHz. The goal of this investigation is to support the development of reliable and efficient automotive traction inverters, with the methods presented being applicable to other applications as well.

Modular multilevel converters (MMCs) are widely employed in power applications due to their modular scalability, excellent harmonic suppression capability, and low-loss characteristics. However, their reliability is constrained by the insulated-gate bipolar transistor (IGBT) devices within the submodules. Consequently, improving the reliability of IGBT devices is crucial for enhancing the overall performance of MMCs. In recent years, state monitoring techniques based on dynamic electrical parameters have emerged as an effective means to improve IGBT reliability. Among these parameters, turn-off time is a key health indicator and is widely used for junction temperature monitoring and failure mode detection. This study presents a non-contact turn-off time measurement method based on the load common-mode current decay during the turn-off process, aiming to overcome the limitations of existing electrical measurement methods. By leveraging existing load current monitoring, real-time monitoring of IGBT turn-off time can be achieved without disrupting normal equipment operation. Experimental results demonstrate that this method can accurately monitor turn-off time and evaluate its impact on variations in load current, capacitor voltage, and junction temperature. The feasibility of this method for practical engineering applications is validated through MMC power-equivalent experimental results.

Combining supercapacitors and power electronic devices, grid-forming static var generators (SVGs) can provide dynamic reactive power compensation while providing inertia support to the system, thereby enhancing the stability of renewable energy systems. However, challenges remain regarding the coordination between the inertia support from grid-forming SVG and the control actions of automatic generation control (AGC) units in renewable energy gathering stations. To address this issue; this paper proposes a coordinated control strategy that accounts for the state of charge (SOC) of supercapacitors, aiming to enhance the inertia support role of grid-forming static var generators (SVG) in renewable energy gathering stations and achieve their coordinated cooperation with the AGC system. By integrating the millisecond-level rapid response capability of grid-forming SVG and the second-level continuous regulation capability of AGC, this strategy establishes a multi-timescale active power support system: at the initial stage of a frequency dip, the grid-forming SVG independently provides rapid inertia support; subsequently, it implements coordinated power allocation with the station-level AGC while comprehensively considering the SOC of supercapacitors and the energy status of wind turbine units, thereby balancing transient frequency stability and the system's long-term continuous regulation capability. Finally, a controller-level hardware-in-the-loop test platform is established for renewable power plants. Tests under typical operating conditions demonstrate the effectiveness and superiority of the proposed strategy, indicating that it can provide enhanced support when frequency fluctuations occur in renewable energy gathering stations.