Fuzzy-logic-based torque control strategy for parallel-type hybridelectric vehicle

In a parallel-type hybrid electric vehicle (HEV), torque assisting and battery recharging control using the electric machine is the key point for efficient driving. In this paper, by adopting the decision-making property of fuzzy logic, the driving map for an HEV is made according to driving conditions. In this fuzzy logic controller, the induction machine torque command is generated from the acceleration pedal stroke and its rotational speed. To construct a proper rule base of fuzzy logic, the dynamo test and road tests for a hybrid powertrain are carried out, where the torque and the nitrogen oxides (NO_x) emission characteristic of the diesel engine and the driver's driving patterns are acquired, respectively. An HEV, a city bus for shuttle service, with the proposed fuzzy-logic-based driving strategy was built and tested at a real service route. It reveals that the improved NO_x emission and better charge balance without an extra battery charger over the conventional deterministic-table-based strategy     

A novel torque-ripple reduction strategy for direct torque control[of induction motor]

This letter presents a simple duty-cycle control scheme for the direct torque control of an induction motor. The scheme reduces torque ripple, controls the average output torque, and reduces the variation in switching frequency. The effectiveness of the proposed technique is demonstrated through experimental results     

Voltage control strategy for maximum torque operation of aninduction machine in the field-weakening region

In this paper, a novel field-weakening scheme for the induction machine is presented. The proposed algorithm, based on the voltage control strategy, ensures the maximum torque operation over the entire field-weakening region without using the machine parameters. Also, by introducing the direct field-oriented (DFO) control, which is insensitive to the variation of machine parameters in the field-weakening region, the drive system can obtain robustness to parameter variations. Moreover, the speed sensorless control can be achieved in the very-high-speed range, where the utilization of the speed sensor is limited. Experimental results for the laboratory induction motor drive system confirm the validity of the proposed control algorithm     

Cost-adaptive motion estimation strategy for high-performance video encoders

An adaptive cost block matching (ACBM) motion estimation technique is proposed to achieve a good compromise between the visual quality of decoded video sequences and the computational cost. Simulation results demonstrate that the ACBM algorithm is able to obtain a better rate-distortion performance that the one given by the full-search algorithm, with reductions of up to 90% in the computational cost.     

基于转矩误差极性的无刷直流电机四象限控制研究

针对无刷直流电机相电流闭环PID控制的控制参数复杂及转矩脉动大的问题,提出了一种基于转矩误差极性的无刷直流电机四象限控制方案。该方案通过在电流环采用设置电流滞环的控制方法,自动判断电机的运行状态及控制电路导通逻辑,从而控制电机正/反转的加减速运行。仿真结果验证了该方法的可行性和有效性,合理设置电流滞环环宽度能有效抑制转矩脉动。     

Autonomous control technique for high-performance switches

A method for creating high-performance switch modules from power transistors and simple control circuits is presented. The method is based on switching function principles by which any type of switch can be represented by an ideal switch in combination with basic logic elements. These high-performance modules can be configured to emulate diodes, thyristors, special resonant devices, or nearly any other switch type. The control is autonomous-it depends on the terminal behavior and external gate signals and requires no additional information from the application circuit. Experimental examples of several switch modules in low-voltage power converters are given. The experimental modules use power MOSFETs and give performance similar to that of synchronous rectifiers but with much greater flexibility. An example is noted in which a module configured to emulate a silicon controlled rectifier (SCR) shows voltage drops below 0.25 V at several amperes of forward current     

A modular control scheme for PMSM speed control with pulsating torque minimization

In this paper, a modular control approach is applied to a permanent-magnet synchronous motor (PMSM) speed control. Based on the functioning of the individual module, the modular approach enables the powerfully intelligent and robust control modules to easily replace any existing module which does not perform well, meanwhile retaining other existing modules which are still effective. Property analysis is first conducted for the existing function modules in a conventional PMSM control system: proportional-integral (PI) speed control module, reference current-generating module, and PI current control module. Next, it is shown that the conventional PMSM controller is not able to reject the torque pulsation which is the main hurdle when PMSM is used as a high-performance servo. By virtue of the internal model, to ify the torque pulsation it is imperative to incorporate an internal model in the feed-through path. This is achieved by replacing the reference current-generating module with an iterative learning control (ILC) module. The ILC module records the cyclic torque and reference current signals over one entire cycle, and then uses those signals to update the reference current for the next cycle. As a consequence, the torque pulsation can be reduced significantly. In order to estimate the torque ripples which may exceed certain bandwidth of a torque transducer, a novel torque estimation module using a gain-shaped sliding-mode observer is further developed to facilitate the implementation of torque learning control. The proposed control system is evaluated through real-time implementation and experimental results validate the effectiveness.     

Band-constrained technique for direct torque control of induction motor

In this paper, a novel technique for the direct torque control (DTC) of an induction motor is proposed, which overcomes the trouble of high torque ripple afflicting the conventional DTC technique. With the novel technique, the inverter voltage vector selected from the switching table is applied for the time interval needed by the torque to reach the upper (or the lower) limit of the band, where the time interval is calculated from a suitable modeling of the torque dynamics. By this approach, the control system emulates the operation of a torque hysteresis controller of analog type since the application time of the inverter voltage vector is dictated by the allowed torque excursion and not by the sampling period. It is shown by experimental results that the technique yields a considerable reduction of the torque ripple. A further and ultimate reduction is obtained by compensating for the delay inherent in the discrete-time operation of the control system. The outcome is that the torque ripple of the motor is constrained within the hysteresis band of the torque controller, for a band of customary value. An ancillary merit of the technique is the almost full elimination of the average torque error inherent in the conventional technique. If the hysteresis band is shrunk, the torque ripple is bound to swing out the band limits. Under this circumstance, an extension of the technique is developed, which helps keep the torque ripple at minimum. To assess the characteristics of the proposed DTC technique, the following quantities: average torque error, rms value of the torque ripple, and inverter switching frequency are measured for different stator flux angular speeds and hysteresis bands of the torque and flux controllers. As a comparison, the same quantities are given for the conventional DTC technique.     

A sensorless torque control for Antagonistic Driven Compliant Joints

Antagonistic Driven Compliant Joints (ADCJs) are object of great interest in current robotics research, representing one of the most widely applied solutions to develop human-like and safe joints for human-robot interaction. Providing the joint with “actively” adjustable hardware compliance, ADCJs have two distinctive features: (1) the joint is powered by two independent “actuation units” and (2) each actuation unit works as a non-linear elastic element with an adjustable resting position. This paper proposes a sensorless torque control strategy suitable for ADCJs actuated robots. This method is based on two steps: (1) off-line characterization of the elasticity of the actuation units, defined by the force–elongation curve and (2) online estimation of the force exerted by each actuation unit, through a direct measure of the joint angle, and of the “resting position” of each actuation unit. The proposed force estimation method can be used to develop two independent force controllers, which can be then combined to regulate the resulting joint torque, with no need of additional torque sensors. The performance of the proposed torque control was evaluated over the shoulder and the elbow ADCJs of the 2-link 2-DOFs planar robotic arm NEURARM. The method proved to work effectively, achieving good performances on the test platform, and represents a suitable alternative to state-of-the-art sensor-based torque controls.     

Predictive direct torque control for the PM synchronous machine

This paper shows that a predictive digital control combined with the principle of direct torque control (DTC) leads to an excellent dynamic behavior of the synchronous machine with surface-mounted permanent magnets and is a real alternative to the classical field-orientated control. The advantages are a DTC control scheme with constant switching frequency and a predictable torque ripple. The settling times of the torque are reduced compared to the classical field-orientated control. The application in servo drives in which the rotor position is always measured can easily be achieved by using a commercial digital signal processor. Numerous simulations and measurements confirm the theoretical work.     

直接转矩控制系统的研究

首先简要介绍直接转矩控制的发展背景,基本原理及其应用范围;其次介绍直接控制的基本特点,它不像矢量控制那样需要复杂的坐标变换;接着简要介绍异步电动机的基本数学模型,得出电机转矩的基本计算公式：之后介绍电机的磁链模型,包括u—i模型及u—i—n模型,并对两种模型的优缺点进行对比分析：最后建立直接转矩控制的仿真模型,并简要分析仿真结果。     

直接转矩控制系统的研究

首先简要介绍直接转矩控制的发展背景,基本原理及其应用范围;其次介绍直接控制的基本特点,它不像矢量控制那样需要复杂的坐标变换;接着简要介绍异步电动机的基本数学模型,得出电机转矩的基本计算公式;之后介绍电机的磁链模型,包括u-i模型及u-i-n模型,并对两种模型的优缺点进行对比分析;最后建立直接转矩控制的仿真模型,并简要分析仿真结果.     

Robust speed control of IM with torque feedforward control

The authors describe a digital signal processor-based (DSP-based) robust speed control for an induction motor (IM) with the load-torque observer and the torque feedforward control. In the proposed system, the load torque is estimated by the minimal-order state observer based on the torque component of a vector-controlled IM. Using the load-torque observer, a speed controller can be provided with a torque feedforward loop, thus realizing a robust speed control system. The control system is composed of a DSP-based controller, a voltage-fed pulsewidth modulated (PWM) transistor inverter and a 3.7 kW IM system. An eccentric load with an arm and a weight is coupled to the IM and it generates the sinusoidal gravitational fluctuating torque. Experimental results show robustness against disturbance torque and system parameter change     

基于Saber的异步电动机直接转矩控制系统仿真

为了验证基于三电平逆变器异步电动机直接转矩控制系统的可行性和有效性,利用Saber仿真软件优良的模块化和分级式的系统仿真能力,建立了异步电动机直接转矩控制系统中定子磁链与电磁转矩观测器、扇区判断、空间电压开关矢量表以及二极管箝位型三电平逆变器等子系统的仿真模型,并根据直接转矩控制原理最终构建了完整的系统仿真模型。利用所构建的系统仿真模型进行了仿真实验,仿真分析结果证明建立的系统模型是有效的,表明直接转矩控制系统具有良好的动态响应性能。     

Nonlinear computed torque control for a high-speed planar parallel manipulator

A new computed torque (CT)-type controller termed nonlinear CT (NCT) controller is developed and applied to a high-speed planar parallel manipulator. The NCT controller is designed by replacing the linear PD in the conventional CT controller with the nonlinear PD (NPD) algorithm. The stability of the parallel manipulator system with the NCT controller is proven using the Lyapunov theorem, and the proposed controller is further proven to guarantee asymptotic convergence to zero of both tracking error and error rate. The superiority of the proposed NCT controller is verified through the trajectory tracking experiments of an actual high-speed planar parallel manipulator, and the experiment results are compared with the CT controller.     

VLSI for high-performance graphic control utilizing multiprocessor architecture

This paper describes the VLSI for high-performance graphic control which utilizes two-level multiprocessor architecture. The VLSI chip is constructed of multiprocessor modules processing in parallel, and each processor module is constructed of multiexecutors using pipeline processing. This dedicated VLSI chip, designated as advanced CRT controller (ACRTC), has three processor modules, each independently controlling drawing, display, and timing. The graphic architecture of the drawing processor, which controls graphic drawing, is described. A high-level graphic language based on anX-Ycoordinate system is adopted. High-speed drawing is realized (drawing rate is 500 ns/pixel for drawing a line) by pipeline processing with three executors, the logical address executor, physical address executor, and color data executor.     

New high-performance thyristor gate control set for line-commutatedconverters

In this paper, a novel implementation to obtain the triggering pulses for thyristorized AC/DC power converters is presented. The system developed is a variant of the digital ramp-and-threshold strategy employing parallel hardware calculation. In order to reduce the number of components otherwise involved, innovative ideas that make feasible the use of only one low-cost field-programmable gate array as the digital core, have been introduced. Based on the proposed topology, a compact high-resolution optimum-speed thyristor gate control circuit is achieved. The resulting system is very flexible and can be easily configured to drive series- or parallel-connected multiple-pulse controlled rectifiers. Practical results are provided     

New robust adaptive control algorithm for high-performance ACdrives

This paper presents a new robust structure for a model reference adaptive control (MRAC) controller for field-oriented-controlled (FOC) drives which requires no prior knowledge of the drive parameters and is guaranteed to provide global asymptotic stability of the closed-loop system. This structure simplifies the design and implementation of the adaptive controller requiring less effort to synthesis than a standard MRAC system. Discussion on theoretical aspects, such as selection of a reference model, stability analysis proof, gain adaptive process, steady-state error elimination, and robustness to unmodeled dynamics are included. The paper describes many practical aspects of the implementation, such as adaptive gain analysis, adaptive rate selection, the gain variation limits, gain windup prevention measure, and initial values. The new robust adaptive controller has been successfully implemented on an FOC drive and experiment results for dynamic tracking, sudden loading and unloading, and gains adaptation under different operation conditions are presented to support the robustness of the proposed controller     

Integration of high-performance spin-orbit torque MRAM devices by 200-mm-wafer manufacturing platform

We demonstrate in-plane field-free-switching spin-orbit torque (SOT) magnetic tunnel junction (MTJ) devices that are capable of low switching current density, fast speed, high reliability, and, most importantly, manufactured uniformly by the 200-mm-wafer platform. The performance of the devices is systematically studied, including their magnetic properties, switching behaviors, endurance and data retention. The successful integration of SOT devices within the 200-mm-wafer manufacturing platform provides a feasible way to industrialize SOT MRAMs. It is expected to obtain excellent performance of the devices by further optimizing the MTJ film stacks and the corresponding fabrication processes in the future.