Robust LPV control of diesel auxiliary power unit for series hybrid electric vehicles

This paper presents a robust gain-scheduling approach for the control of diesel auxiliary power unit (APU) for series hybrid electric vehicles (SHEVs), using the linear parameter-varying (LPV) techniques. An average physical model of the diesel APU is established, which combines the subsystem models including diesel engine, synchronous generator, and three-phase diode rectifier in an elegant way. The nonlinear system model is then formulated as a quasi-LPV form with parametric uncertainty and augmented with performance objectives in a robust control framework. As a solution to this type of control problem, a robust LPV control synthesis method is proposed and its numerical implementation issues are also considered. Simulation results verify the performance of the proposed robust LPV controller.     

Maximum Power Point Tracking in Variable Speed Wind Turbine Based on Permanent Magnet Synchronous Generator Using Maximum Torque Sliding Mode Control Strategy

The present study was carried out in order to track the maximum power point in a variable speed turbine by minimizing electromechanical torque changes using a sliding mode control strategy. In this strategy, first, the rotor speed is set at an optimal point for different wind speeds. As a result of which, the tip speed ratio reaches an optimal point, mechanical power coefficient is maximized, and wind turbine produces its maximum power and mechanical torque. Then, the maximum mechanical torque is tracked using electromechanical torque. In this technique, tracking error integral of maximum mechanical torque, the error, and the derivative of error are used as state variables. During changes in wind speed, sliding mode control is designed to absorb the maximum energy from the wind and minimize the response time of maximum power point tracking (MPPT). In this method, the actual control input signal is formed from a second order integral operation of the original sliding mode control input signal. The result of the second order integral in this model includes control signal integrity, full chattering attenuation, and prevention from large fluctuations in the power generator output. The simulation results, calculated by using MATLAB/m-file software, have shown the effectiveness of the proposed control strategy for wind energy systems based on the permanent magnet synchronous generator (PMSG).     

A torque and speed coupling hybrid drivetrain-architecture, control, and simulation

In this paper, a speed and torque coupling hybrid drivetrain is introduced. In this drivetrain, a planetary gear unit and a generator/motor decouple the engine speed from the vehicle wheel speed. Also, another shaft-fixed gear unit and traction motor decouple the engine torque from the vehicle wheel torque. Thus, the engine can operate within its optimal speed and torque region, and at the same time, can directly deliver its torque to the driven wheels. This paper discussed the fundamentals architecture, design, control, and simulation of the drivetrain.     

Two-Level VSC Based Predictive Direct Torque Control of the Doubly Fed Induction Machine With Reduced Torque and Flux Ripples at Low Constant Switching Frequency

In this paper, a new predictive direct torque control (DTC) strategy of the doubly fed induction machine (DFIM) is presented. It is especially designed to operate at a considerably low constant switching frequency, reducing the electromagnetic torque and rotor flux ripples, in order to provide good steady-state and fast dynamic performances. This control is convenient for high power drive and generator applications, with restricted switching frequency. The DFIM is connected to the grid by the stator and the rotor is fed by a two level voltage source converter. In addition, this control method allows to implement a technique that reduces the switching power losses of the converter. Finally, experimental results show that the proposed DTC method effectively reduces the torque and flux ripples at low switching frequency, even under variable speed operation conditions.     

A Secondary Voltage Control Strategy for Transmission Level Interconnection of Wind Generation

This paper addresses implementation issues associated with secondary voltage control in a doubly-fed induction generator based wind farm. The effects of different system parameters on the performance of the control are considered, namely the short circuit ratio of the interconnection and the inherent communication delay between the wind park and the remote bus. In addition, a strategy for allocation reactive power requirements to each of the generators within the wind park is proposed. The system is developed and simulated for a wind park consisting of six wind generators connected to a typical transmission system. The paper proposes an optimal tracking secondary voltage control method developed to achieve effective voltage regulation, enhance the network voltage profile and provide optimal reactive power compensation to the interconnected power system. The performance of the controller is compared with secondary voltage control at one selected bus, primary voltage control and the optimal voltage profile obtained from the optimal power flow analysis. The performance of the controllers is tested for steady state operation and in response to system contingencies, taking into account the impact of communication time delays and short circuit ratio (SCRs). Simulation results are presented to demonstrate the capability of the controllers to provide the desired reactive power compensation and voltage support to the electric power grid.     

Application of electrically peaking hybrid (ELPH) propulsion systemto a full-size passenger car with simulated design verification

An electrically peaking hybrid electric (ELPH) propulsion system is being developed that has a parallel configuration. A small engine is used to supply power approximately equal to the average load power. The operation of the engine is managed by a vehicle controller and an engine controller such that the engine always operates with nearly full load-the optimal fuel economy operation. An induction motor is used to supply the peaking power required by the electrically peaking load. The motor can also absorb the excess power of the engine while the load power is less than the peak. This power, along with the regenerative braking power, can be used to charge the batteries on board to maintain the battery state-of-charge (SOC) at a reasonable level. With the electrically peaking principle, two control strategies for the drive train have been developed. One is called maximum battery SOC control strategy, by which the engine and electric motor are controlled so that the battery SOC is maintained at its top level as much as possible. This control strategy may be used in urban driving in which accelerating and decelerating driving is common and high-battery SOC is absolutely important for normal driving. The other control strategy is called engine turn-on and turn-off control by which the engine is controlled to operate in a turn-on and turn-off manner. This control strategy may be used in highway driving. Based on the ELPH principle and the drive train control strategies, a drive train for a full-size five-seat passenger car has been designed and verified using the V-ELPH computer simulation package     

变速恒频双馈风力发电系统最优风能捕获控制

从分析风力机运行特性出发，研究实现最优风能捕获的系统控制方法。并采用定子磁场定向的矢量控制技术，对双馈发电机转子进行交流励磁，实现发电机有功、无功及转速的独立控制，从而获得最大风能捕获的高效发电运行。仿真结果验证了文中所提出控制策略的正确性和有效性。     

Extremum-seeking nonlinear controllers for a human exercise machine

In this paper, a next generation exercise machine controller is developed for a single degree of freedom (DOF) system to maximize the user's power output and ensure passivity with the user. In an effort to optimize the user's power expenditure, a desired velocity trajectory is developed that seeks the unknown user-dependent optimal velocity setpoint. Two extremum-seeking algorithms are presented (e.g., Kristic and Deng, and Tuekosky et al.) that seek the optimal velocity setpoint while ensuring the trajectory is sufficiently differentiable. To track the reference trajectory and to ensure passivity, two controllers are developed. The first controller is developed based on the assumption that the user's torque input can be measured. A second controller is designed that estimates the user's torque input. Both controllers are proven to ensure that the exercise machine remains passive with respect to the user's power output. The controllers are proven to yield semiglobal tracking through Lyapunov-based analyses. Proof-of-concept experimental results are provided that illustrate the performance of the torque estimation controller.     

High-Speed Control of IPMSM Drives Using Improved Fuzzy Logic Algorithms

This paper presents an improved fuzzy logic controller (FLC) for an interior permanent magnet synchronous motor (IPMSM) for high-performance industrial drive applications. In the proposed control scheme for high-speed operations above the rated speed, the operating limits of IPMSM are expanded by incorporating the maximum torque per ampere operation in constant torque region and the flux-weakening operation in constant power region. The power ratings of the motor and the inverter are considered in developing the control algorithm. A new and simple FLC is utilized as a speed controller. The FLC is developed to have less computational burden, which makes it suitable for real-time implementation, particularly at high-speed operating conditions. The complete drive is implemented in real-time using digital signal processor (DSP) controller board DS 1102 on a laboratory 1-hp IPM motor. The efficiency of the proposed control scheme is evaluated through both experimental and computer simulation results. The proposed controller is found to be robust for high-speed applications     

Thyristor-based current-fed drive with direct power control for permanent magnet-assisted synchronous reluctance generator

This paper proposes a robust and simple direct power control (DPC) of a thyristor-based current-fed drive for generator applications. A current-fed drive and permanent magnet-assisted synchronous reluctance generator (PMa-SynRG) are investigated to deliver 3 kW power using a combustion engine. The current-fed drive utilises a thyristor-based three-phase rectifier to convert generator power to DC-link power and a single-phase current-fed inverter to supply a single-phase inductive load. In addition, a new control algorithm is developed based on DPC for the current-fed drive. The DC-link voltage-based DPC is proposed in order to directly control the output power. The goal of the DPC is to maintain the DC-link voltage at the required output power operating point. The DPC has advantages such as a simple algorithm for constant speed operation. Another feature of the developed current-fed drive is its inherent capability to provide generating action by making the PMa-SynRG operates as a generator, rectifying the phase voltages by means of the three-phase rectifier and feeding the power into the load. These features make the current-fed drive a good candidate for driving any type of synchronous generators including the proposed PMa-SynRG.     

An improved DTC-SVM method for matrix converter drives using a deadbeat scheme

In this paper, a simple direct torque control (DTC) method for sensorless matrix converter drives is proposed, which is characterized by a simple structure, minimal torque ripple and unity input power factor. Also, a good sensorless speed-control performance in the low speed operation is obtained, while maintaining constant switching frequency and fast torque dynamics. It is possible to combine the advantages of matrix converters with the advantages of the DTC strategy using space vector modulation a deadbeat algorithm in the stator flux reference frame. Experimental results are shown to illustrate the feasibility of the proposed strategy.     

Control Strategy for a 42-V Waste-Heat Thermoelectric Vehicle

A 42-V waste-heat thermoelectric vehicle is employed as a potential application of thermoelectric generators for fuel economy improvement and emissions reduction. The 42-V waste-heat thermoelectric vehicle currently in development employs an assemblage driving system consisting of a waste-heat thermoelectric generator, a 42-V powernet, and an integrated starter and generator (ISG). The waste-heat thermoelectric generator also functions as a power supply. To optimize the utilization of the waste-heat energy generated by the thermoelectric generator, an electric assist control strategy and a torque split control strategy are proposed herein. Through the development of relevant systems and strategies, including the thermoelectric generator and an electric bus system, two vehicle models are established and compared using the ADVISOR platform based on MATLAB/Simulink. The calculation results show improved fuel economy and emissions performance resulting from the integration of the torque split control strategy into the 42-V waste-heat thermoelectric vehicle.     

Sliding-mode control of doubly-fed generator for optimum power curve tracking

Aiming to achieve superior tracking of a predefined optimum power curve, a simple standard sliding-mode controller (SMC) for the rotor-side converter feeding a doubly-fed induction generator (DFIG) is synthesised. Besides being robust against DFIG parameter variations, it is implementable on FPGA, and does not require PWM or SVM modulation. Results of real-time hardware-in-the-loop evaluation, obtained when running the proposed SMC together with an MRAS observer for sensorless control, are reported.     

Analysis and design of microprocessor-based vector-controlledinduction motor drives

The design and implementation of controllers for induction motor drives under vector control is considered. The control of induction motor drives is considered in both constant torque and constant horsepower operation regions. A systematic mathematical formulation is presented for designing motor controllers. These include conventional proportional-integral controllers and more advanced frequency-domain optimal controllers. A 32-b microprocessor-based experimental control system is implemented for verifying the proposed control strategies. The theoretical results are validated by the experimental work     

A dead-beat type digital controller for the direct torque control of an induction motor

In this paper, a dead-beat type digital controller has been introduced to overcome the problems of a conventional direct torque controller. The proposed induction motor drive with a digital dead-beat controller shows good transient response and negligible steady-state error even at a low switching frequency, which is needed for high power machines used for transportation. Including the rotor dynamics, the stability condition and steady-state error of the proposed control system have been examined in the z-plane. In addition, the good performance has been verified through the simulation and experiment. The flux and torque controllers have been designed with only stator voltage equations in the stator flux reference frame in order to take advantages of the direct torque control. Therefore, the proposed flux and torque controllers have simple forms and can be easily designed and implemented.     

Energy Management Fuzzy Logic Supervisory for Electric Vehicle Power Supplies System

This paper introduces an energy management strategy based on fuzzy logic supervisory for road electric vehicle, combining a fuel cell power source and two energy storage devices, i.e., batteries and ultracapacitors. The control strategy is designed to achieve the high-efficiency operation region of the individual power source and to regulate current and voltage at peak and average power demand, without compromising the performance and efficiency of the overall system. A multiple-input power electronic converter makes the interface among generator, energy storage devices, and the voltage dc-link bus. Classical regulators implement the control loops of each input of the converter. The supervisory system coordinates the power flows among the power sources and the load. The paper is mainly focused on the fuzzy logic supervisory for energy management of a specific power electronic converter control algorithm. Nevertheless, the proposed system can be easily adapted to other converters arrangements or to distributed generation applications. Simulation and experimental results on a 3-kW prototype prove that the fuzzy logic is a suitable energy management control strategy.     

Robust fuzzy neural network sliding mode control scheme for IPMSM drives

This article proposes a robust fuzzy neural network sliding mode control (FNNSMC) law for interior permanent magnet synchronous motor (IPMSM) drives. The proposed control strategy not only guarantees accurate and fast command speed tracking but also it ensures the robustness to system uncertainties and sudden speed and load changes. The proposed speed controller encompasses three control terms: a decoupling control term which compensates for nonlinear coupling factors using nominal parameters, a fuzzy neural network (FNN) control term which approximates the ideal control components and a sliding mode control (SMC) term which is proposed to compensate for the errors of that approximation. Next, an online FNN training methodology, which is developed using the Lyapunov stability theorem and the gradient descent method, is proposed to enhance the learning capability of the FNN. Moreover, the maximum torque per ampere (MTPA) control is incorporated to maximise the torque generation in the constant torque region and increase the efficiency of the IPMSM drives. To verify the effectiveness of the proposed robust FNNSMC, simulations and experiments are performed by using MATLAB/Simulink platform and a TI TMS320F28335 DSP on a prototype IPMSM drive setup, respectively. Finally, the simulated and experimental results indicate that the proposed design scheme can achieve much better control performances (e.g. more rapid transient response and smaller steady-state error) when compared to the conventional SMC method, especially in the case that there exist system uncertainties.     

Two families of sliding mode controllers for a doubly-fed induction generator in an isolated generation system

In this paper the authors consider the Sliding Mode Control (SMC) of a Doubly Fed Induction Generator (DFIG), supplying an isolated RL load in a Variable Speed-Constant Frequency (VSCF) generation system. It must be reminded that in electric machines the existence of parameter changes, caused by several reasons like winding temperature variation, hysteresis and saturation, is well recognized, but rarely accounted for. For this reason, SMC has been considered. SMC has various attractive features like order reduction, robustness, disturbance rejection, and, sometimes, simple implementation. In this paper, some ideas of SMC applied by Utkin et. al. for controlling the speed or torque of a squirrel-cage induction motor are used to design two families of controllers for regulating amplitude and frequency of the voltage generated by a DFIG. First simulation results are presented as well.     

Wind energy conversion system associated to a flywheel energy storage system

This paper deals with the study of a variable speed wind induction generator associated to a flywheel energy storage system. Direct torque control strategy is applied to control the induction generator where both rotor flux and DC bus voltage are controlled through the application of the standard switching table for operations in the 4 quadrants. The flywheel energy storage system is used to improve the quality of the electric power delivered by the wind generator. The proposed system, controlled thanks to Direct Torque Control (DTC) strategy, is validated through simulations. The obtained results are presented and discussed.     

A flexible active and reactive power control strategy for avariable speed constant frequency generating system

Variable-speed constant-frequency generating systems are used in wind power, hydroelectric power, aerospace, and naval power generation applications to enhance efficiency and reduce friction. In these applications, an attractive candidate is the slip power recovery system comprising a doubly excited induction machine or doubly excited brushless reluctance machine and PWM power converters with a DC link. In this paper, a flexible active and reactive power control strategy is developed, such that the optimal torque-speed profile of the turbine can be followed and overall reactive power can be controlled, while the machine copper losses have been minimized. At the same time, harmonics injected into the power network have also been minimized. In this manner, the system can function as both a highly-efficient power generator and a flexible reactive power compensator