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In this article, the advanced angle control (AAC) for the active rectifier (AR) is proposed to improve the output power of doubly salient electromagnetic generator systems. The AAC AR is an optimization by turning on the switches in advance with an angle based on the angular position control (APC) and pulsewidth modulation (PWM) ARs. The operation principle of the AAC in ARs is different from that in the inverters. The phase inductance variation is analyzed. The inductance flat top at load condition is utilized to accelerate the commutation process and enlarge the phase current. The unified analysis is proposed by summarizing the four states of the conduction modes in the AR. The analysis of the proposed AAC strategies, the conventional APC, and PWM strategies are unified. The output power of AAC APC ARs is significantly improved compared with that of the conventional AR. The copper loss, iron loss, and torque ripple are reduced. The AAC strategies are compared with conventional strategies. The optimized performances of AAC strategies are verified by finite-element analysis and experimental results. [ABSTRACT FROM AUTHOR]

A doubly salient electromagnetic starter/ generator (DSESG) system based on the bidirectional converter (BDC) is proposed, in this article. The BDC is operated as an inverter in starting mode and as an active rectifier (AR) in generation mode. Compared to the conventional DSESG system, which is based on an inverter and a diode rectifier or a discrete inverter/rectifier unit (IRU), the configuration is simplified and the weight is reduced. Since the output voltage is improved by the angular position control (APC), field and phase currents are redistributed. The copper loss optimization control (CLOC) for the AR is proposed. The copper loss is analyzed based on the extreme learning machine (ELM) and the turn-off angles are selected. The copper loss is minimized and the heat is reduced. The copper loss and heat generation are also balanced in the field and phase windings to decrease the temperature of the field windings at low speed. Experimental verifications are conducted on a 9 kW DSESG prototype. The effectiveness of the proposed ELM-based CLOC is verified by simulation and experiments. A lighter and simpler DSESG system with reduced loss is presented. [ABSTRACT FROM AUTHOR]

Due to its high power density, the fractional slot concentrated winding permanent magnet synchronous machine (PMSM) is a competitive candidate for the aircraft starter generator (SG) system. However, the short circuit (SC) fault, especially the turn-to-turn SC fault, is the obstruct crux in aviation applications. The turn-to-turn SC current can be restricted to a permissible level with higher reactance and the current injection mitigation method. However, higher self-inductance always leads to lower power density. So far, there have been no numerical criteria for the tradeoff between the two characteristics in machine design. In this article, an analytical model based on flux distribution is used to estimate the SC current. The effectiveness of the d-axis current injection mitigation method is numerically analyzed in the series and parallel connected windings individually. The requirement for PMSMs to survive the turn-to-turn SC fault is derived. The mathematical analysis is verified by finite-element analysis and experiments on a 12-slot, 10-pole PMSM. This article provides theoretical support for designing high-performance permanent magnet starter generator (PMSG) with SC current mitigation ability for the aviation power system. [ABSTRACT FROM AUTHOR]

The doubly salient electromagnetic generator (DSEG) is gaining increasing attention in aircraft high voltage dc generator application due to its simplicity and de-excitation ability. However, the field winding inductance and the dc-link capacitor result in a larger electrical time constant. The dynamic response is decelerated, leading to difficulties in meeting aircraft electrical power standards. Minimum transient point tracking (MTPT) strategy based on the trajectory with minimum field current variation is proposed for the DSEG system with an angular position control (APC) controlled rectifier. Since the dc load current depends on both field current and the turn-off angle, the change in the field current is minimized and the dc load current is varied by controlling the turn-off angle. The trajectory of the optimized turn-off angle is studied to partly or fully fill the gap between the field currents at different loads. By tracking the MTPT trajectory, the change of the field current is decreased during the sudden load changes. The transient process is accelerated and the voltage variation is suppressed. In most operations, the voltage variation can be even neglected under both loaded and unloaded conditions. A 9-kW DSEG system based on controlled rectifier is implemented. The MTPT strategy is verified by experiments. The performances of the diode rectifier, controlled rectifier with fixed turn-off angle, and controlled rectifier with MTPT are compared. The dynamic performance is improved by the proposed method, making the DSEG more competitive in aircraft applications. [ABSTRACT FROM AUTHOR]