Tzuen-Lih Chern

Design of discrete integral variable structure control systems and application to a brushless DC motor control

A discrete integral variable structure control (DIVSC) approach is presented to achieve accurate servo-tracking in the presence of load disturbance and plant parameter variations. Conditions are derived to ensure the existence of non-ideal sliding motion. This scheme also proves that the describing motion in the non-ideal sliding region will be close to the ideal sliding motion. Further, procedures are proposed for determining the control function, the coefficients of the switching plane and the integral control gain. The procedures can cause the resultant system to have the desired properties. A microcomputer-based brushless DC motor servo position control system using the DIVSC approach is illustrated. Simulation results are compared with the PI controller to demonstrate the potential of the controller. Experimental results present the practical capability of the proposed controller.

DSP-based integral variable structure model following control for brushless DC motor drivers

The design and implementation of digital signal processor (DSP) microprocessor-based brushless DC motor servo control drivers are presented. The integral variable structure model following control (IVSMFC) approach is presented to achieve robust accurate servo tracking. A design procedure is developed for determining the control function, the coefficients of the switching plane, and the integral control gain such that the error between the state of the model and the controlled plant is to be minimized. Simulation and experimental results show that the proposed approach can achieve accurate velocity/position servo tracking in the presence of load disturbance and plant parameter variations.

Integral-variable-structure-control-based adaptive speed estimator and resistance identifier for an induction motor

The proposed system adopts neither position nor velocity sensor but uses only measurement of the stator current and stator phase voltage commands to estimate the rotor velocity and to identify the resistance of the stator and rotor for an ac induction motor. In the proposed scheme, the integral variable structure control approach is firstly applied to design an observer and identifier. Also, Lyapunov functions are chosen for determining the adaptive law for a speed estimator and a resistance identifier of an induction motor. Simulation results demonstrate that the proposed approach can achieve accurate speed estimation and resistance identification under load disturbance and motor parameter variation.

Microprocessor-based modified discrete integral variable-structure control for UPS

This paper presents a digital signal processor microprocessor-based high-performance uninterruptible power system (UPS). It also modifies the integral variable-structure control (IVSC) approach to be more suitable for the UPS, which is tracking a sinusoidal AC voltage with specified frequency and amplitude. Since the implementation of the control laws has tended to the digital microprocessor, the paper extends the modified IVSC to the discrete time domain. Procedures are developed for determining the control function, the switching plane and the integral control gain, so that the system has desired properties. Simulation and experimental results show that the proposed scheme can supply a high-quality voltage power source in the presence of load disturbance and parameter variation.

High power factor Flyback converter for LED driver with Boundary Conduction Mode control

A varying-frequency control Flyback rectifier for LED driving in Boundary-Conduction Mode (BCM) is presented. Comparing with Discontinuous-Conduction Mode, BCM has the advantages like smaller coupling inductor current, less current stress for circuit component, slight output current ripple, and higher power factor performance. For lower output application circumstance, the boundary conduction mode can be chosen with smaller inductance value. In this control scheme, input line voltage sensing, analog multiplier/divider and inner current loop are neglected. Design and analysis for BCM control circuit are derived and simulated. To verify the ideal vary-frequency controller, the circuit experiment has been applied to driving LED module, and stabilized the output current. The experimental results show that the system can provide constant current output with high power factor and it also compared with the system is operating in DCM.

Brief Paper: Automatic Voltage Regulator Design by Modified Discrete Integral Variable Structure Model Following Control

In power systems, the automatic voltage regulator (AVR) is designed to make the terminal voltage to accurately track the deviation of the reference voltage. To achieve the desired requirements, this paper proposes the modified discrete integral variable structure model following control (MDIVSMFC) approach. The MDIVSMFC approach comprises a reference model part for specifying the design requirements and a MDIVSC part for minimizing the errors between the plant and model. The non-ideal sliding motion is introduced to take the place of the ideal sliding motion in discrete-time systems. Its existence conditions are used to adapt the proposed approach to the discrete systems. The application of MDIVSMFC to an AVR design is developed. Procedures for determining the control function, the coefficients of the sliding surface and the integral control gain are also proposed in detail. Simulation results are compared with the IEEE type-I voltage regulator to demonstrate that the proposed scheme can achieve fast and robust responses.

DSP-based induction motor drives using integral variable structure model following control approach

A DSP-based AC induction motor driver is presented. The integral variable structure model following control (IVSMFC) approach is presented to achieve robust accurate servo tracking. The results of simulation and experiment demonstrate the potential of the proposed scheme.

The Research of Smart Li-ion Battery Management System

This research presents a smart Li-ion battery management system. It can accurately estimate residual capacity and be able to monitor various information of Li-ion battery. In order to obtain more effectively estimated method, first of all an automatic measuring platform is built, for recording data of Li-ion battery under different utilizing condition, through analysis data and characteristics. The modified-coulomb-measuring method is developed to compensate error for measurement deviation at different states of output current and environmental temperature. This principle is implemented by digital signal processor; experimental results are shown to verify the precisions of this proposed system.

Sensorless speed control of BLDC motor using six step square wave and rotor position detection

This paper presents a brushless DC motor (BLDCM) control system that does not require Hall sensor and speed encoder for an air conditioner fan motor. Using low cost circuits, the zero-crossing points are detected to estimate the commutated timing and speed information. Hall element shortcoming can therefore be eliminated. A modified six-step square wave pattern with pulse-width modulation is developed to simplify the conventional coordinate transformations technique. To verify the proposed method, a prototype fan motor controller is constructed and tested. Experimental results show that the proposed method has high efficiency and good performance.

Single-stage Flyback converter for led driver with inductor voltage detection power factor correction

A constant current output Flyback converter with power factor correction used for LED driving is presented in this paper. The inductor voltage detection method is applied and acquired the inductor voltage to generate the control signal. Based on this design principle, the inner loop of input current shaping is eliminating, the input voltage sensing and multiplier are also not necessary. The simulation and experimental results are provided to demonstrate the effectiveness of the control scheme based on the lab prototype boards. The output load condition is set from full load to light load, and the results show that the system drives the LEDs with high power factor.