Jieng-Jang Liu

Frequency adaptive control technique for rejecting periodic runout

This paper proposes a novel adaptive controller for rejecting the periodic runout of a track-following system in the compact disk drive (CDD) with dual actuators. The control objective is to attenuate adaptively the specific frequency contents of runout disturbances without amplifying its rest harmonics. This controller can be implemented in a plug-in manner to an existing feedback control system without changing the original control setup. It is applicable to both the spindle modes of constant linear and constant angular velocity for various operation speeds. The experimental results show that the novel control strategy leads to a satisfactory performance in terms of the reduction of tracking error of CDDs.

An Electric Gearshift With Ultracapacitors for the Power Train of an Electric Vehicle With a Directly Driven Wheel Motor

A novel electric gearshift with ultracapacitors is designed for the power train of a directly driven electric vehicle. The power train consists of two major subsystems: electric propulsion and energy source. The electric propulsion subsystem is composed of a dedicated wheel motor and its drive; the energy source subsystem is equipped with a stack of lead-acid batteries and ultracapacitor cells. This electric gearshift combines different parallel and serial connections of batteries, motor windings, and ultracapacitors to accommodate various driving patterns in the permissible range of speed and torque. A control core, which is realized by a field-programmable gate array, is employed to manage the energy source and direct optimal propulsion to extend the speed range of constant power, and thereby improve vehicle performance in terms of efficiency, acceleration, and driving range.

Multiobjective Optimal Design and Soft Landing Control of an Electromagnetic Valve Actuator for a Camless Engine

This paper presents a multiobjective optimal design and an energy compensation control for the soft valve landing of an electromagnetic valve actuator in internal combustion engines. This axisymmetric and cylindrical actuator is used to achieve continuous and independent valve timing and lifting without mechanical cams, which features a hybrid magnetomotive force with permanent magnet (PM) and electromagnet, and a secondary air gap to prevent the PM irreversibly demagnetizing. The dynamics of the electromagnetic valve are modeled with an equivalent magnetic circuit, which is used to perform both sensitivity analysis and an optimal design function to satisfy multiple objectives, such as magnetic holding force, release current, and its rising time. The energy compensation control in which the positive and negative work of an armature stroke is equalized enables a zero landing velocity to be achieved. The experimental results from a prototype actuator show that the landing velocity can be greatly reduced by adjusting the duty cycle of the landing current, and the actuating power is greatly reduced after the energy compensation control is applied.

Electromechanical Valve Actuator with Hybrid MMF for Camless Engine

Abstract As one of variable valve timing (VVT) approaches, the electromechanical valve actuator (EMVA) uses solenoid to actuate valve movement independently for the application of internal combustion engine. This paper proposed an EMVA structure by incorporating the hybrid magneto-motive force (MMF) implementation in which the magnetic flux is combined by the coil excitation and permanent magnets. Making use of the dedicated flux arrangement, the proposed device can be used to fulfill the VVT features with reduced power source requirement and less electric device components. A dual flux channels EMVA is detailed and the design procedures are presented. Comparing with the conventional EMV, the proposed prototype shows a lot of advantages such as compactness, high temperature tolerance, fast response, relieve of starting current, and variable current actuating timing.

Improved estimation of residual capacity of batteries for electric vehicles

Abstract This paper proposes an improved means of estimation for the residual capacity of lead‐acid batteries used in electric vehicles. The residual capacity of batteries in commercial products is usually indicated by the state of charge (SOC) of the battery set, in terms of the measurement of amp‐hours, or roughly an instant voltage. More practical and accurate SOC in the operation of electric vehicles must consider the original capacity when the battery is first installed, capacity deficiency due to high discharge rate, capacity dissipated in internal resistance, and correcting parameters for the battery aging process. The proposed estimation techniques include the amp‐hours measurement weighted by a correction function of various discharge rates, the transient open‐circuit voltage measurement to compensate for the energy dissipation from internal resistance, and the reset of parameters in the linear function of SOC and open‐circuit voltage for the aging effect. A monitoring circuit with a programmable logic chip is implemented, and the experimental results show that a more accurate indication of SOC is achieved using the modified estimation techniques, namely a weighted ampere‐hour measurement with transient open‐circuit voltage combined with the aging effect.

Multifunctional optimal design of an electromagnetic valve actuator with hybrid magnetomotive force for a camless engine

This paper proposes a novel design of an electromagnetic valve actuation system for internal combustion engines. This electromagnetic valve uses a hybrid magnetomotive force with a permanent magnet and electromagnet to control the variable timing and soft landing of the valve. Under the restriction of engine space and operation, the dynamics of the electromagnetic valve are modeled with an equivalent magnetic circuit, which is used to perform both sensitivity analysis and an optimal design function to satisfy multiple objectives, such as magnetic holding force, release current, and its rising time. The final design is verified and refined by finite element analysis. A prototype is fabricated and the experimental results show that the dynamical performances of the electromagnetic valve are satisfactory and may be improved by advanced feedback controls.

Disk Wobble Control in Optical Disk Drives

Focusing errors in optical disk drives comprise significant periodic components and an eventful dc content. The dc component is not explicitly taken into account in many periodic compensation methods. This paper investigates the design of adaptive feedforward cancellation (AFC) and frequency adaptive control technique (FACT) algorithms for periodic components as well as dc disturbance compensation. Both algorithms are applied as a plug-in module to an optical disk drive for demonstrating their facility in the reduction of focusing errors. By making good use of frequency sampling filter (FSF), the real-time harmonic identification can be fulfilled in FACT method for various playing speeds. Analysis and experimental results show that FACT has better properties than AFC in terms of dc cancellation and harmonic independence. It is also shown that AFC fails when both the dc content and harmonics are compensated simultaneously.

Energy compensation method for soft-landing control in camless engine with electromagnetic valve actuator

This paper proposes a control strategy involving energy compensation for the soft-landing of an electromagnetic valve actuator in internal combustion engines. This axisymmetric and cylindrical actuator features a hybrid magnetomotive force with permanent magnet and electromagnet, and a secondary air gap to prevent the permanent magnet irreversibly demagnetizing. It is a straightforward theory in which the positive and negative work of an armature stroke is equalized, enabling a zero landing velocity to be achieved. The resultant of positive and negative work is a function of valve landing velocity, which depends on the release current that releases the armature from one seating position, and the landing current that attracts the armature to the opposite seating position. The magnitude and duty cycle of the release and landing currents are investigated for soft-landing via observation of armature displacement and velocity. The experimental results show that the landing velocity can be greatly reduced by adjusting the duty cycle of the landing current, and the actuating power is greatly reduced after the energy compensation control is applied.

Frequency adaptive control technique of compact disk drives for rejecting periodic runout

This paper proposes a novel adaptive controller for rejecting the periodic runout of a track following system in the compact disk drives. The control objective is to attenuate adaptively the specific frequency contents of runout disturbances without amplifying its rest harmonics. Being dependent on the position of the disk, the proposed controller is applicable to both the spindle modes of constant linear velocity (CLV) and constant angular velocity (CAV) for various operation speeds. The experimental results show that the novel control strategy leads to a satisfactory performance in terms of the reduction of tracking error of compact disk drives.

Design of power-assisted motor for vehicle air-conditioning systems

This paper proposes an optimal design process for a 1.26 kW power-assisted permanent magnet synchronous motor (PMSM) for a vehicle air-conditioning (A/C) system. The PMSM specifications are based on traditional vehicle compressor products. The preliminary design stage involved determination of the motor type, winding type and number of slots and poles. The energy method was then used to construct a 2D magnetic circuit model of the power-assisted motor. Sensitivity analysis was used to determine the most important design variables, which were selected to optimize the objective functions, including output torque, torque ripple, weight and efficiency. The optimal design was determined by combining the Multifunctional Optimization System Tool (MOST) with the 2-D magnetic circuit model. In addition, direct- and quadrature-axis inductances were calculated to prove that the saliency of the half-inset magnet rotor configuration is greater than unity.