Miran Rodic

Speed-sensorless sliding-mode torque control of an induction motor

Novel induction motor control optimizing both torque response and efficiency is proposed in the paper. The main contribution of the paper is a new structure of rotor flux observer aimed at the speed-sensorless operation of an induction machine servo drive at both low and high speed, where rapid speed changes can occur. The control differs from the conventional field-oriented control. Stator and rotor flux in stator fixed coordinates are controlled instead of the stator current components in rotor field coordinates i/sub sd/ and i/sub sq/. In principle, the proposed method is based on driving the stator flux toward the reference stator flux vector defined by the input command, which are the reference torque and the reference rotor flux. The magnitude and orientation angle of the rotor flux of the induction motor are determined by the output of the closed-loop rotor flux observer based on sliding-mode control and Lyapunov theory. Simulations and experimental tests are provided to evaluate the consistency and performance of the proposed control technique.

Neural network sliding mode robot control

This paper develops a method for neural network control design with sliding modes in which robustness is inherent. Neural network control is formulated to become a class of variable structure (VSS) control. Sliding modes are used to determine best values for parameters in neural network learning rules, thereby robustness in learning control can be improved. A switching manifold is prescribed and the phase trajectory is demanded to satisfy both, the reaching condition and the sliding condition for sliding modes.

Neural network application in sliding mode control systems

Application of neural network controller design in dynamical systems with sliding mode motion is introduced to improve performance of the discrete-time sliding mode system. Neural network controller with learning rule based on sliding mode algorithm, is proposed to assure calculation of unknown part of the equivalent control in the presence of the plant uncertainties. Developed algorithm is robust to parameter variations and external disturbances. The effectiveness of the neural network sliding mode controllers is verified by experiments.

High Precision Motion Control of Servo Drives

In this paper, we investigate the advantages and feasibility of motor control using very fast (in megahertz) switching in place of traditional amplifiers. We also propose integrated motion-control architecture based on discrete-event control approach to be implemented in digital logic at an equally high rate. A switching controller combines the current and motion feedback paths into a single loop. A model-based observer estimates the load torque. When compared to second-order controllers implemented with traditional amplifiers, the proposed design promises increased performance, better efficiency, and improved load estimation. Simple implementation makes concepts of switching control very attractive in motion-control systems like control of dc or ac servomotors. The control algorithm designed by the proposed approach can be easily implemented on field programmable gate array platforms.

Control Design in Mechatronic Systems Using Dynamic Emulation of Mechanical Loads

The paper presents and analyses rapid prototyping methods for the dynamic emulation of mechanical loads. Actual system (prototype) is replaced by the torque controlled electromechanical load, for which the required torque is calculated through the closed-loop nonlinear control algorithm. The load is connected mechanically to the drive shaft, using the clutch. Two methods are presented and compared. Also possible applications in the control design for variable speed and torque drives are described.

DCM-Based Zero-Voltage Switching Control of a Bidirectional DC–DC Converter With Variable Switching Frequency

This paper investigates a control approach for achieving reliable zero-voltage switching transitions within the entire operating range of a conventional nonisolated bidirectional dc-dc converter that utilizes synchronous rectification. The approach is based on operation in the discontinuous conduction mode with a constant reversed current of sufficient amplitude, which is achieved by load-dependent variation of the switching frequency. This paper focuses on the obtained resonant voltage transitions and provides analytical models for determining the reversed current and timing parameters that would ensure safe, reliable, and highly efficient operation of the converter. In addition, the proposed approach solves the synchronous transistors spurious turn-on and body diode reverse recovery induced issues, does not require any additional components or circuitry for its realization, and can be entirely implemented within a digital signal controller. The effectiveness and performance of the presented control approach was confirmed in a 1-kW experimental bidirectional dc-dc converter that achieved 97% efficiency over a wide range of output powers at switching frequencies above 100 kHz.

Comparison of sliding mode observer and extended Kaiman filter for sensorless DTC-controlled induction motor drive

This paper deals with two different observers for sensorless DTC-controlled induction motor (IM) drives. First is sliding mode observer (SMO), second is extended Kaiman filter (EKF). The main objective of this paper is experimental analysis of limits of these observers and their behavior in challenging low-speed region. Theoretical conclusions presented in this paper are verified by experiments made on designed IM drive prototypes of rated power of 250 W.

Dynamic emulation of mechanical loads — position control approach

An approach to dynamic emulation of mechanical loads is presented, which can be used for the design and validation of variable position, speed and torque control algorithms. Actual mechanism is replaced by a dynamometer. Torque demand of the dynamometer is calculated from the closed-loop algorithm. Numerical model of the emulated load is used as a reference model and the impact of the test rig dynamics is compensated.

Speed Sensorless Variable Structure Torque Control of Induction Motor

Induction motor speed sensorless torque control, which allows operation at low and zero speed, optimizing both torque response and efficiency, is proposed. The control is quite different than the conventional field-oriented or direct torque control. A new discontinuous stator current FPGA based controller and rotor flux observer based on sliding mode and Lyapunov theory are developed analyzed and experimentally verified. A smooth transition into the field weakening region and the full utilization of the inverter current and voltage capability are possible. The reference tracking performance of speed and rotor flux is demonstrated in terms of transient characteristics by experimental results.

Sliding mode application in speed sensorless torque control of an induction motor

Abstract Induction motor speed sensorless torque control, which allows operation at low and zero speed, optimizing both torque response and efficiency, is proposed. The control is quite different than the conventional field-oriented or direct torque control. The produced torque is explicitly continuous output variable of control. A new stator and rotor flux controller/observer based on continuous sliding mode and Lyapunov theory are developed. A smooth transition into the field weakening region and the full utilization of the inverter current and voltage capability are possible. The reference tracking performance of torque and rotor flux is demonstrated in terms of transient characteristics by experimental results.