The stability problem induced by constant power loads (CPLs) is becoming more prominent in more electric aircraft. In this article, the stabilization issue of dc distribution bus with dual-active-bridge (DAB) converters was investigated. On the basis of voltage regulation, an active damping solution based on model predictive control (MPC) was proposed by explicitly incorporating a stabilization term into a cost function. In this solution, to ensure the output voltage performance with a smaller steady-state error and a dynamic voltage overshoot, an adaptive weighting factor was adopted with a stray resistor taken into account. A theoretical design of the weighting factors was performed using the artificial neural network (ANN) method. The proposed approach could supply stiff load voltage and provide good dc-link voltage stabilization, as well as load voltage overshoot clamping. These findings were verified through the computer simulations and practical experiments of an 800-W converter prototype with a switching frequency of 20 kHz, an input voltage of 270 V, and an output voltage of 270 V.

For the safety of the wound-rotor synchronous machine (WRSM) in aircraft applications, the overvoltage at the motor terminals, electromagnetic interference (EMI) performance, and bearing currents as well as the loss analysis are the core areas to be addressed. The high-frequency (HF) modeling method of the WRSM, which has a strong relationship with all these core areas, is a very critical theme. In this paper, a measurement-based wide-frequency (WF) modeling method to characterize the impedance of the WRSM is proposed to build a straightforward correlation between fundamental models and HF parasitic circuit elements. In this paper, the voltage-behind-reactance method is applied to demonstrate the rotor-angle-dependent characters in the low-frequency domain, while the vector fitting method is used to parameterize the HF branch for high-accuracy consideration. By doing this, a WF electrical model with multistage RLC units is formed, which comprehensively considers both the saliency character of the machine and frequency range. The WF model is also compatible with the circuit-based simulation. Finally, the EMI prediction orientated simulation and experimental results are implemented on a 10 kVA WRSM prototype to verify the correctness and advantages of the proposed modeling method.

The T-type three-level inverters have enormous promise in medium-voltage drives for aircraft electric-propulsion applications. The phase-shifted carrier-based pulsewidth modulation (CBPWM) is a viable solution to reduce the damage caused by the common-mode voltage (CMV) of such inverters. However, the beneficial effect of triangular carrier phase shifting on CMV suppression has not been well explored, and it is still unknown what range of phase shift angles may guarantee CMV suppression for arbitrary modulation index. Therefore, aiming at the T-type three-level inverter, this study offers a thorough examination of the relationship between CMV reduction and the phase-shifted CBPWM approach. The characterization of the maximum CMV is revealed within the full modulation index range based on the sector segmentation and regular sampling. Then, an adaptive phase shift pulsewidth modulation (APS-PWM) strategy is developed to achieve consistent CMV reduction. The maximum CMV of the inverter may be efficiently eliminated under the proposed strategy by dynamic carrier phase shifting. Finally, experiments verify the correctness of the analysis and the feasibility of the proposed strategy.

A multi‐objective optimisation design method for passive power filter devices is proposed to solve the input current harmonic suppression problem of the aircraft starter/generator system. The parameters of the filter device are optimised by using the particle swarm optimisation algorithm. The proposed algorithm takes harmonic parameters, DC voltage drop, total volume and weight as the optimisation target. With these optimisations, the filter has the minimal volume and weight, while the current harmonic and the DC side voltage drop are able to meet the power quality requirements. This approach improves the filter design procedure with advantages of the reduced amount of calculation. Finally, theoretical analysis and computer simulation validate the effectiveness and viability of the presented algorithm.

In modular multilevel converter (MMC), the existence of second- and other even-order harmonics in the circulating currents can have a negative impact on the operation of the converter. To mitigate the dominant second-order harmonic circulating current, the harmonic extraction method plays an important role in steady-state accuracy and dynamic performance of circulating current suppression (CCS). This paper proposes a time-delayed filter based approach to suppress the circulating current. Operating principles and filtering characteristics of the time-delayed filter are investigated. The proposed solution achieves accurate suppressing and frequency-deviation adaptation with simple implementation. Experiments from a single-phase grid-connected MMC have been conducted to validate the correctness of the proposed solution.

In multistages aircraft starter/generator system, the main machine (MM) and main exciter (ME) are fed by a generalized dual-inverter configuration, allowing for common-mode voltage (CMV) elimination. However, the distinction in load impedances and voltage requirements between the two subinverters has evidently contributed to the subload asymmetry, which may impair the suppression effect of system common mode (CM) noises. This article presents a CMV minimization method for the generalized dual-inverter application. The available freedom, such as the selection and action sequence of voltage vectors, is appropriately arranged in the suggested implementation to eliminate the total CMV, restrict the sub-CMVs and fulfill the voltage requirements of subinverters all at the same time. In the meanwhile, a theoretical study is performed to evaluate the CM noise features of zero CMV technique in the generalized dual inverter-fed system. In the situation of subload asymmetry, the premise and main influence element for CM noise reduction are assessed. Finally, these findings are verified by simulation and experiments.