Hoang Le-Huy

Minimization of Torque Ripple in Brushless DC Motor Drives

Torque characteristics of brushless dc motors are studied in terms of the EMF and the feed currents for two feeding schemes: two-phase feeding and three-phase feeding. Various techniques for minimizing torque ripple are considered and discussed. For three-phase feeding systems, a selective harmonics elimination technique is studied and its effectiveness is evaluated.

Operation of a Self-Controlled Synchronous Motor Without a Shaft Position Sensor

The starting operation of a self-controlled synchronous motor without a shaft position sensor is studied. A method which permits the determination of the rotor position at a standstill by voltage sensing is explained. Various forced commutation techniques and starting, strategies are considered. Torque characteristics for natural commutation operation are studied, providing simple formulas with good precision. Experimental results obtained with a prototype drive system are given.

Digital Position Servo System: A State Variable Feedback System

A digital position control system using a dc motor fed by a four-quadrant transistor chopper is presented. All control functions are handled by a microcomputer requiring only an incremental encoder for position and speed sensing. Two control approaches are considered: the classical control approach and the state feedback approach. For each approach, static and dynamic control performance is studied in terms of system parameters. Experimental-results are given and discussed.

A Multifunction DC-DC Converter as Versatile Power Conditioner

A multifunction dc-dc converter that can be used as a single power conditioner connecting the source, the storage, and the load in solar or wind energy systems is presented. Operation of the converter in four configurations is analyzed and simulated. Application of the converter is discussed, and experimental results obtained with a prototype circuit are given.

A Synchronous Thyristorized DC Motor Drive

A thyristorized dc motor speed control system using phase-locked loop principle is presented. Linear model analysis is given and control performance is studied in terms of system parameters using the root-locus technique. Practical design aspects are discussed, and experimental results obtained with a prototype system intended for a separately excited ¿-hp dc motor are given.

A digitally controlled thyristor trigger circuit

A high-performance thyristor trigger circuit in which the delay angle is controlled by an eight-bit digital word is described. Application of the proposed circuit in microprocessor-based thyristor power-control systems is discussed.

Resonant DC link inverter-fed ac machines control

The use of resonant converter principle in variable-speed ac drives is presented. A control strategy to obtain high-frequency quasi sinusoidal dc link waveform permitting zero voltage switching is proposed. This operation results in reduction of commutation stress and switching losses in the power devices. Operation of a current-controlled three-phase resonant dc link converter is studied. Simulation and experimental results are given.

A synchronous DC motor speed control system

A high-efficiency synchronous speed control system for dc motors using the phase-locked technique is presented. The performance is derived in terms of system parameters. Some experimental results with a 1/4-hp dc motor are given.

Autoadaptive Chopper for Speed Regulation of a Wound Rotor Induction Machine

An optimized design is presented of an SCR forced commutation ircuit permitting autoadaptive commutation under transient currents, independent of supply voltage. Different constraints and criteria are discussed, together with experimental results on dc choppers used for the speed regulation of wound rotor induction machines.