Yang Qi

Aviation electrification is a promising solution to tackle the global energy crisis, which fosters electric aircraft. Besides, hybrid power systems involving the fuel cell, battery, and ultracapacitor are promising to provide propulsion power. Serving as the key device, fuel cells suffer from undesirable operation conditions, e.g., start–stop transition, heavy load, light load, and power variation, which degrade their operation efficiency and lifespan. To address this issue, a decentralized power allocation strategy is proposed in this article. In this method, the ultracapacitor is regulated based on a virtual capacitance to handle dynamic power demand. Besides, the battery is exploited to undertake partial steady-state load power when in heavy- and light-load conditions, allowing the fuel cell to operate in the high-efficiency range to the greatest extent possible. Consequently, both dynamic and steady-state power allocations are realized, ensuring high-efficiency and reliable operation of the hybrid power systems. Meanwhile, note that the control algorithms in this method for all three units are implemented based on their local information, respectively, no dedicated communication network is required. Finally, the validation of this strategy is proven by hardware-in-loop (HIL) test results in various scenarios.

Magnetic-coupled energy routers provide an effective solution for interfacing the load with hybrid energy storage systems. Particularly, it is important to achieve dynamic power sharing based on the characteristics of hybrid energy storage. This target is conventionally realized by the phase-shift control. However, the multiple-input and multiple-output (MIMO) feature of the energy router complicates the model and results in multiple control loops. Inspired by the virtual synchronous machine (VSM) control, this paper first proposes an emulated inertia and damping control for high-frequency magnetic-coupled energy routers. The proposed method can realize perfect dynamic power sharing in a simple and decentralized way, which improves the system modularity and flexibility. The principle is explicitly explained and validated by hardware experimental results.

Transformer rectifier units (TRUs) are widely used to convert variable-frequency AC (VFAC) voltage to DC voltage in the more electric aircrafts (MEA). The DC output of TRU contains frequency-dependent voltage ripples, which significantly degrade the DC-link power quality. To solve the issue, this article proposes an adaptive DC-link voltage ripple compensation approach that accommodates 360–800 Hz VFAC operation range. The proposed control strategy can be simply implemented on the DC–DC converter that already exists in the MEA power system. Though proper design, the auxiliary voltage ripple compensation can be decoupled with the DC–DC converter basic power-flow control in the frequency domain. Finally, hardware experimental results are presented to validate the feasibility of the proposed method.

To address the inadequate dynamic response characteristics of hybrid energy storage systems (HESS) in aviation dc microgrids under pulsed power loads caused by traditional PI control, this article proposes an optimized feedforward compensation strategy based on dynamic allocation of load-current and derivative weighting. This method bypasses the transient response limitations inherent in conventional PI control and incorporates a dynamic compensation term linked to the load current derivative directly into the duty cycle unit, enhancing the traditional dual-loop control framework. By perceiving real-time load current variations, the approach proactively adjusts power allocation coefficients among energy storage units. Compared with traditional PI control, it significantly reduces dc bus voltage recovery time under pulse load conditions, effectively enhancing bus voltage robustness and power quality. Furthermore, the article provides a theoretical analysis of the dynamic performance and stability of the proposed method from a system transfer function perspective. Finally, numerical simulations and experimental results validate the efficacy of the improved approach. The findings offer a theoretical foundation and technical reference for optimized power allocation design of HESS in high-reliability aviation dc microgrids.

The hybrid energy storage systems (HESSs), often configured with battery and supercapacitor (SC) combinations, can effectively regulate power imbalances between generation and loads within more electric aircraft (MEA) dc microgrids. However, traditional control exhibits limitation in precisely tracking high-frequency components within SC current loop. To address this deficiency, this article proposes a novel current control strategy enhancing SC current tracking capability in HESS. Departing from conventional approaches, the proposed strategy eliminates the proportional-integral (PI) controller from the SC current loop, instead integrating SC current regulation with pulse-width modulation (PWM) to form a modified PWM unit. Consequently, the input signal of this modified PWM unit derives from given function of the SC current, while the amplitude of the PWM carrier signal is reformulated to vary instantaneously with the SC current. The variable-carrier-based PWM method accelerates the realization of SC current synthesis. Furthermore, a small-signal model is also explored to deeply investigate the stability of the HESS. Subsequent simulations are conducted to verify the performance across multiple scenarios. Experimental validation conducted on a 25 kW HESS power stage demonstrates the theoretical feasibility of the proposed control methodology.