Hybrid Synchronized PWM Schemes for Closed-Loop Current Control of High-Power Motor Drives

© 1982-2012 IEEE. For high-power drives, switching frequency is usually restricted to several hundred hertz to minimize the switching losses. To maintain the current distortions and torque ripples at a reasonable level, synchronized pulse patterns with half-wave and quarter-wave symmetries are employed. The analytic compensation is derived by Fourier analysis to ensure the proportionality between the voltage reference and the output voltage of an inverter for pulse width modulation (PWM) with low pulse ratio. A simple yet very effective method with varying sampling rate is proposed to maintain synchronization even for fast dynamic processes. The fast and smooth transition between different PWM patterns is achieved by compensating phase angle of the voltage reference through the analysis of stator flux trajectories. The effectiveness of the proposed method is validated on a down-scaled 2.2-kW induction motor drives

Design and Control of Power Converters 2019

In this book, 20 papers focused on different fields of power electronics are gathered. Approximately half of the papers are focused on different control issues and techniques, ranging from the computer-aided design of digital compensators to more specific approaches such as fuzzy or sliding control techniques. The rest of the papers are focused on the design of novel topologies. The fields in which these controls and topologies are applied are varied: MMCs, photovoltaic systems, supercapacitors and traction systems, LEDs, wireless power transfer, etc

A novel power management and control design framework for resilient operation of microgrids

This thesis concerns the investigation of the integration of the microgrid, a form of future electric grids, with renewable energy sources, and electric vehicles. It presents an innovative modular tri-level hierarchical management and control design framework for the future grid as a radical departure from the ‘centralised’ paradigm in conventional systems, by capturing and exploiting the unique characteristics of a host of new actors in the energy arena - renewable energy sources, storage systems and electric vehicles. The formulation of the tri-level hierarchical management and control design framework involves a new perspective on the problem description of the power management of EVs within a microgrid, with the consideration of, among others, the bi-directional energy flow between storage and renewable sources. The chronological structure of the tri-level hierarchical management operation facilitates a modular power management and control framework from three levels: Microgrid Operator (MGO), Charging Station Operator (CSO), and Electric Vehicle Operator (EVO). At the top level is the MGO that handles long-term decisions of balancing the power flow between the Distributed Generators (DGs) and the electrical demand for a restructure realistic microgrid model. Optimal scheduling operation of the DGs and EVs is used within the MGO to minimise the total combined operating and emission costs of a hybrid microgrid including the unit commitment strategy. The results have convincingly revealed that discharging EVs could reduce the total cost of the microgrid operation. At the middle level is the CSO that manages medium-term decisions of centralising the operation of aggregated EVs connected to the bus-bar of the microgrid. An energy management concept of charging or discharging the power of EVs in different situations includes the impacts of frequency and voltage deviation on the system, which is developed upon the MGO model above. Comprehensive case studies show that the EVs can act as a regulator of the microgrid, and can control their participating role by discharging active or reactive power in mitigating frequency and/or voltage deviations. Finally, at the low level is the EVO that handles the short-term decisions of decentralising the functioning of an EV and essential power interfacing circuitry, as well as the generation of low-level switching functions. EVO level is a novel Power and Energy Management System (PEMS), which is further structured into three modular, hierarchical processes: Energy Management Shell (EMS), Power Management Shell (PMS), and Power Electronic Shell (PES). The shells operate chronologically with a different object and a different period term. Controlling the power electronics interfacing circuitry is an essential part of the integration of EVs into the microgrid within the EMS. A modified, multi-level, H-bridge cascade inverter without the use of a main (bulky) inductor is proposed to achieve good performance, high power density, and high efficiency. The proposed inverter can operate with multiple energy resources connected in series to create a synergized energy system. In addition, the integration of EVs into a simulated microgrid environment via a modified multi-level architecture with a novel method of Space Vector Modulation (SVM) by the PES is implemented and validated experimentally. The results from the SVM implementation demonstrate a viable alternative switching scheme for high-performance inverters in EV applications. The comprehensive simulation results from the MGO and CSO models, together with the experimental results at the EVO level, not only validate the distinctive functionality of each layer within a novel synergy to harness multiple energy resources, but also serve to provide compelling evidence for the potential of the proposed energy management and control framework in the design of future electric grids. The design framework provides an essential design to for grid modernisation

Analysis and Mitigation of Common-mode Behavior in Hybrid Vehicle Applications

Modeling techniques to predict common-mode (CM) current in an electric drive intended for a hybrid vehicle are examined. A particular focus is on the derivation of a common-mode equivalent circuit (CMEC) in which machines, cables, and passives are represented by their passive coupling paths to ground and power electronic devices are replaced by equivalent voltage sources. The interconnection of components is accomplished using a judicious selection of a reference point used to define CM voltage. Circuit-based simulation results are presented for a system consisting of a permanent magnet generator coupled to an active rectifier that is providing power to an inverter/permanent magnet motor. The simulation results are compared to those obtained from a detailed system model in which the switching behavior of all semiconductor devices is represented. It is shown that the CM current predicted using the CM equivalent circuit closely matches that obtained using the detailed system model. Finally, several switching strategies are presented for three-phase, three-leg converters with the intent of reducing the CM voltage at a single or multitude of frequencies. The CM equivalent circuit is used to explore the impact that these strategies have on CM current in modern power electronics systems as well as future systems that will be dominated by wide-bandgap semiconductor devices

Six-Step Operation of Three-Phase PMSM Based on Flux Vector Prediction

학위논문(박사) -- 서울대학교대학원 : 공과대학 전기·정보공학부, 2023. 2. 설승기.3상 인버터의 식스-스텝 운전(Six-step operation)은 전압 육각형의 꼭짓점 벡터만을 이용하여 직류단 전압 이용률을 최대화하는 운전 기법이다. 식스-스텝 운전을 통하여, 주어진 직류단 전압 조건 하에서 전동기의 가용 토크를 최대화 할 수 있다. 또한 펄스폭 변조(Pulse-width modulation, PWM)와 비교하여, 인버터의 스위칭 손실이 현저히 줄어든다는 장점이 있다. 이러한 이유로 높은 출력 토크 및 인버터 효율을 얻을 수 있는 식스-스텝 운전에 대한 연구가 활발하게 이루어지고 있다. 식스-스텝 운전시 전압의 크기는 최대화된 상태이므로, 출력 전압의 위상만이 정상상태 자유도로 남게 된다. 다수의 선행 연구들은 전압각에 초점을 맞추어 기본파 전압각의 변화분을 입력으로 가지는 선형 시스템으로 영구자석 동기 전동기(Permanent-magnet synchronous motor, PMSM)의 식스-스텝 운전을 모델링하고, 모델링에 기반하여 주파수 영역(Frequency domain) 분석을 통해 제어기를 설계하였다. 하지만 해당 모델링은 평형점 근방의 소신호 분석을 바탕으로 수립되므로, 대신호에 대한 정확성이 보장되지 않는다. 또한 주파수 영역에서의 분석은 출력 전압의 기본파 성분에만 초점을 맞추기 때문에, 식스-스텝 운전의 고조파 전압 성분이 동특성에 끼치는 영향이 고려되지 않는다. 이러한 모델링 오차는 식스-스텝 운전의 동특성 향상에 있어 제약 사항으로 작용한다. 본 논문은 PMSM 식스-스텝 운전의 동특성 향상 방법에 대하여 연구한다. 회전자 기준 좌표계 상에서 식스-스텝 운전의 순시 전압은 회전자의 반대 방향으로 회전하는 효과를 지닌다. 본 논문에서는 순시 전압의 회전 효과를 반영하기 위하여 시간 영역(Time domain)에서 분석을 진행한다. 회전자 기준 좌표계 상에서 전압 인가 시간에 따른 순시 자속 궤적을 수식화하고, 이를 바탕으로 PMSM 식스-스텝 운전의 시간-최적(Time-optimal) 절환 방법을 유도한다. 회전자 기준 좌표계 상에서 자속의 시간-최적 경로는 목표 운전점을 크게 우회하는 형태로 나타난다. 이러한 경로는 회전자 기준 좌표계에서 설계된 선형 제어기를 통해 구현하기 어렵고, 개루프 형태를 취해야 한다는 문제점이 존재한다. 반면, 정지 좌표계 상에서 자속의 시간-최적 경로는 출력 토크 증가 상황에선 지름길로, 감소 상황에선 우회로로 나타난다. 본 논문에서는 정지 좌표계 자속 궤적에 대한 고찰을 바탕으로 폐루프 형태의 시간-최적 절환 방법을 제안한다. 제안하는 방법은 데드비트(Dead-beat) 제어 구조를 취하며, 자속 벡터 예측을 통하여 자속이 시간-최적의 경로를 따르도록 전압 벡터를 인가한다. 본 논문에서는 시간-최적 절환 방법을 적용한 전류 제어 구조를 제안한다. 시간-최적 절환 방법을 하위 제어기로 구성하여 식스-스텝 운전의 동특성을 확보하며, 상위 전류 제어기를 통하여 전류 제한에 대한 모니터링 및 토크 제어를 수행한다. 30 kW 급 하이브리드 자동차 견인용 IPMSM을 대상으로, 제안하는 방법의 성능을 시뮬레이션 및 실험으로 검증하였다. 제안하는 방법을 통하여 식스-스텝 운전의 동특성을 현저히 개선할 수 있음을 보였다.Six-step operation of a three-phase inverter maximizes the utilization of dc-link voltage using only the six vertices of the voltage hexagon. Thus, the six-step operation can enhance the torque capability of ac motors. Furthermore, the switching loss of the inverter is conspicuously reduced compared to the PWM operation. Due to the advantages of the six-step operation, a number of studies have been conducted on the six-step operation. Since the magnitude of the output voltage is maximized under the six-step operation, the phase angle of the output voltage remains as the only degree of freedom. Focusing on the voltage angle, most research has modeled the six-step operation of a permanent-magnet synchronous motor (PMSM) as a linear system with a change in the fundamental component of the voltage angle; the controllers have been designed based on the frequency domain analysis with a linearized model. However, this model is based on small signal analysis near the equilibrium point. This means that the accuracy of the large signal is not guaranteed. In addition, the frequency domain analysis only focuses on the fundamental component of the output voltage, so it does not take into account the effect of the harmonic component on the dynamic performance. This modeling error makes it difficult to improve the dynamic performance of the six-step operation. This thesis presents a method for improving the dynamic performance of PMSMs six-step operation. In the rotor reference frame, the instantaneous voltage vector of the six-step operation has the effect of rotating in the opposite direction of the rotor. In this thesis, the analysis proceeds in the time domain to reflect the effects of the instantaneous voltage. The instantaneous trajectory of the stator flux-linkage is formulated according to the time interval of the applied voltage. A time-optimal transition method for the six-step operation of PMSM is theoretically derived from this formulation. In the rotor reference frame, the time-optimal path of the flux vector seems like a detour to the target locus. It is difficult to implement using a linear regulator designed in the rotor reference frame, and an open-loop structure is needed. In contrast, in the stationary reference frame, the time-optimal path appears as a shortcut when the output torque increases and a detour when the output torque decreases. Based on the analysis in the stationary reference frame, this thesis proposes a closed-loop time-optimal transition method. The proposed method utilizes a dead-beat control structure and applies a voltage vector so that the flux vector follows a time-optimal path through the prediction. This thesis also proposes a current control structure to be used in conjunction with the previously mentioned time-optimal transition method. By configuring the time-optimal transition method as an inner controller, the dynamic performance of the six-step operation is secured; the torque control with the current limit monitoring is performed through the outer current controller. The performance of the proposed method is verified through simulation and experiments for a 30 kW-IPMSM for HEV application. It is shown that the dynamic performance of the six-step operation can be conspicuously improved through the proposed method.제 1장 서론 1 1.1 연구의 배경 1 1.2 연구의 목적 7 1.3 논문의 구성 9 제 2장 식스-스텝 운전 제어에 관한 기존 연구 10 2.1 직접 토크 제어 구조를 이용한 식스-스텝 운전 10 2.1.1 정상상태 토크 식 기반의 방법 [20]-[27] 10 2.1.2 PMSM의 동특성을 고려한 전압각 제어 [28], [29] 14 2.2 전류 제어 구조를 이용한 식스-스텝 운전 17 2.2.1 전압 지령 수정 방법을 통한 식스-스텝 운전 [30] 17 2.2.2 가변 인가 시간 제어를 통한 q축 전류 제어 [35] 21 2.3 데드비트 자속 제어 구조를 이용한 식스-스텝 운전 24 제 3장 모델 기반의 시간-최적 운전점 절환 28 3.1 영구자석 전동기의 식스-스텝 운전 모델링 29 3.1.1 식스-스텝 운전의 순시 전압 벡터 29 3.1.2 영구자석 전동기의 자속 궤적 모델링 31 3.1.3 정상상태 자속 궤적 33 3.1.4 절환에 따른 자속 궤적 36 3.2 운전점 절환 방법에 대한 분석 38 3.2.1 한 단계에 걸친 절환 40 3.2.2 두 단계에 걸친 절환 42 3.2.3 세 단계에 걸친 절환 43 3.2.4 네 단계에 걸친 절환 48 3.3 시뮬레이션 및 실험 검증 52 3.3.1 제안하는 절환 방법의 구현 및 검증 52 3.3.2 시뮬레이션 결과 56 3.3.3 실험 결과 60 3.4 모델 기반 개루프 절환 방법의 한계점 65 제 4장 자속 벡터 예측을 통한 시간-최적 운전점 절환 방법 66 4.1 정지 좌표계 상에서의 자속 궤적 분석 67 4.1.1 정상상태 자속 궤적 67 4.1.2 운전점 절환 시 자속 궤적 71 4.1.3 비인접 전압 벡터 및 PWM을 이용한 절환 방법 검토 75 4.2 제안하는 방법의 구성 80 4.2.1 정지 좌표계 자속 추정기 80 4.2.2 자속 지령 생성기 83 4.2.3 예측 기반의 자속 제어기 85 4.2.4 톱니 반송파 기반의 전압 벡터 스위칭 88 4.3 시뮬레이션 및 실험 결과 89 4.3.1 시뮬레이션 결과 89 4.3.2 실험 결과 96 4.4 제안하는 시간-최적 절환 방법의 전달 함수 분석 102 제 5장 시간-최적 절환 방법을 적용한 토크 제어 105 5.1 제어 구조에 대한 검토 105 5.1.1 참조표를 이용하는 구조 105 5.1.2 직접 토크 제어 구조 106 5.1.3 자속 기준 제어 구조 108 5.2 제안하는 식스-스텝 운전 제어 111 5.2.1 SFOC q축 전류 제어 구조 111 5.2.2 제어기 설계 고려 사항 112 5.2.3 제어기 형태에 따른 소신호 전달 함수 분석 115 5.2.4 제어기 이득 설정 120 5.3 시뮬레이션 및 실험 결과 127 5.3.1 시뮬레이션 결과 127 5.3.2 실험 결과 133 제 6장 기저 속도 부근 PWM 모드와의 절환 141 6.1 과변조 영역에서의 전류 제어 143 6.1.1 역연산 안티 와인드업의 영향 [62] 143 6.1.2 전압 지령 수정을 통한 전류 동특성 개선 방법 [30] 153 6.1.3 능동 저항을 이용한 복소 벡터 전류 제어기 동특성 개선 156 6.2 PWM 모드와 식스-스텝 모드 간의 절환 방법 161 6.3 시뮬레이션 및 실험 결과 163 6.3.1 시뮬레이션 결과 163 6.3.2 실험 결과 166 제 7장 결론 170 7.1 연구 결과 170 7.2 향후 과제 및 후속 연구 172 부 록 173 참고 문헌 185 Abstract 189박

Investigation of Millimetre Wave Generation by stimulated Brillouin scattering for Radio Over Fibre Applications

The rising demand for greater bandwidth and increased flexibility in modern telecommunication systems has lead to increased research activities in the field of Millimetre Wave-Photonics. The combination of an optical access network and the radio propagation of high data-rate signals provides a solution to meet these demands. Such structures are also known as Radio Over Fibre Systems. They implement the optical Millimetre Wave generation in a central station and the transmission of radio waves via a remote antenna unit to the radio cell. The expected data rate is very high, due to the fact that both the optical and the radio-link provide a large transmission bandwidth. This dissertation concerns the investigation of a new and simple method for the flexible generation of Millimetre Waves for application in Radio Over Fibre systems. The method is based on the heterodyne detection of two optical waves in a photo detector. By externally amplitude modulating the optical wave, different sidebands are generated. Two of these sidebands are selected and amplified by the non-linear effect of stimulated Brillouin scattering. As a gain medium, a standard single mode fibre is used. According to the theoretical investigation, very good carrier performances are possible with this method, and a computer simulation shows little degradation in the signals during their propagation in the system. The measured results are in strong agreement with the theoretical analysis. Experimental results show that the system can be fully utilised as a Radio Over Fibre system. The thesis is divided into five main parts: Introduction – Theory – Simulation – Experiment – Conclusion. In the Introduction, an overview of the current methods of Millimetre Wave Generation, Radio Over Fibre and the nonlinear effects of Brillouin scattering is given. In the theoretical section, a differential equation system which mathematically describes the system is derived and also solved numerically. With a proof of the concept set-up, the simulated results are compared with the experimental data. In the last section the work is conclude and future tasks are discus

Articles publicats per investigadors de l'ETSEIB indexats al Journal Citation Reports: 2013

Informe que recull els 297 treballs publicats per 203 investigadors de l'Escola Tècnica Superior d'Enginyeria Industrial de Barcelona (ETSEIB) en revistes indexades al Journal Citation Reports durant l’any 2013.Postprint (published version