An Advanced Dual-Carrier-Based Multi-Optimized PWM Strategy of Three-Level Neutral-Point-Clamped Converters for More-Electric-Aircraft Applications

Since three-level neutral-point-clamped (3L-NPC) power generation units bring much competitiveness to the next-generation electric starter/generator (ESG) system for more-electric-aircraft (MEA) applications, the versatile multi-optimized pulse-width-modulation (PWM) becomes a key enabler to this technology. Regarding the mission profile of the state-of-art ESG, the operating points at the cruise feature a high modulation index and low power factor. This means that the neutral-point potential (NPP) fluctuation becomes severe. Besides, if switching states are not configured properly, not only could the lifetime of capacitors be threatened but also irreversible damage to bearing insulation occurs due to the common-mode voltage (CMV), followed by devastating effects on the reliability of other avionic facilities. Given the limitations of the 270VDC unipolar dc-bus structure, deep flux-weakening currents are constantly required for the high speed, resulting in more machine copper losses. To address these issues without any hardware-level efforts, an advanced PWM strategy with dual-carrier-based implementation is proposed in this article, which achieves boosted dc-link voltage utilization, CMV reduction and balanced NPP at the same time. Simulation results obtained from Simulink/PLECS and experimental results obtained from a 45 kW, 32 krpm ESG prototype system verify the effectiveness and feasibility of the proposed algorithm

Online sensorless position estimation for switched reluctance motors using one current sensor

This paper proposes an online sensorless rotor position estimation technique for switched reluctance motors (SRMs) using just one current sensor. It is achieved by first decoupling the excitation current from the bus current. Two phase-shifted pulse width modulation signals are injected into the relevant lower transistors in the asymmetrical half-bridge converter for short intervals during each current fundamental cycle. Analog-to-digital converters are triggered in the pause middles of the dual pulse to separate the bus current for excitation current recognition. Next, the rotor position is estimated from the excitation current, by a current-rise-time method in the current-chopping-control mode in a low-speed operation and a current-gradient method in the voltage-pulse-control mode in a high-speed operation. The proposed scheme requires only a bus current sensor and a minor change to the converter circuit, without a need for individual phase current sensors or additional detection devices, achieving a more compact and cost-effective drive. The performance of the sensorless SRM drive is fully investigated. The simulation and experiments on a 750-W three-phase 12/8-pole SRM are carried out to verify the effectiveness of the proposed scheme

Online sensorless position estimation for switched reluctance motors using one current sensor

This paper proposes an online sensorless rotor position estimation technique for switched reluctance motors (SRMs) using just one current sensor. It is achieved by first decoupling the excitation current from the bus current. Two phase-shifted pulse width modulation signals are injected into the relevant lower transistors in the asymmetrical half-bridge converter for short intervals during each current fundamental cycle. Analog-to-digital converters are triggered in the pause middles of the dual pulse to separate the bus current for excitation current recognition. Next, the rotor position is estimated from the excitation current, by a current-rise-time method in the current-chopping-control mode in a low-speed operation and a current-gradient method in the voltage-pulse-control mode in a high-speed operation. The proposed scheme requires only a bus current sensor and a minor change to the converter circuit, without a need for individual phase current sensors or additional detection devices, achieving a more compact and cost-effective drive. The performance of the sensorless SRM drive is fully investigated. The simulation and experiments on a 750-W three-phase 12/8-pole SRM are carried out to verify the effectiveness of the proposed scheme

Vector-controlled induction motor drive with minimal number of sensors

У тези су предложена два унапређена алгоритма управљања асинхроним мотором у условима када је број сензора који се користи у погону минималан. Број сензора који се користи у повратној спрези управљачког алгоритма сведен је на само један струјни сензор који мери струју једносмерног међукола погонског инвертора. Предложене методе елиминишу карактеристично изобличење реконструисаних фазних струја и постижу бољи квалитет и перформансе управљања у односу на конвенционалну методу. Сва аналитичка разматрања у тези су праћена одговарајућим експерименталним резултатима, који потврђују ефикасност предложених метода управљања.U tezi su predložena dva unapređena algoritma upravljanja asinhronim motorom u uslovima kada je broj senzora koji se koristi u pogonu minimalan. Broj senzora koji se koristi u povratnoj sprezi upravljačkog algoritma sveden je na samo jedan strujni senzor koji meri struju jednosmernog međukola pogonskog invertora. Predložene metode eliminišu karakteristično izobličenje rekonstruisanih faznih struja i postižu bolji kvalitet i performanse upravljanja u odnosu na konvencionalnu metodu. Sva analitička razmatranja u tezi su praćena odgovarajućim eksperimentalnim rezultatima, koji potvrđuju efikasnost predloženih metoda upravljanja.This thesis proposes two improved and robust induction motor drive control methods, in the case when there is a minimal number of sensors for providing feedback signals. Number of used sensors is reduced to only one current sensor measuring the inverter dc-link current. Proposed methods cancels offset jitter-like waveform distortion present in the reconstructed motor phase currents, and achieves higher quality and drive performance regard to conventional current reconstruction mechanism. Effectivness of the proposed methods are verified on developed HIL (hardware-in-the-loop) platform and laboratory induction motor drive prototype