Suneel K. Kommuri

A Robust Observer-Based Sensor Fault-Tolerant Control for PMSM in Electric Vehicles

This paper investigates the problem of automatic speed tracking control of an electric vehicle (EV) that is powered by a permanent-magnet synchronous motor (PMSM). A reconfiguration scheme, based on higher order sliding mode (HOSM) observer, is proposed in the event of sensor faults/failures to maintain a good control performance. The corresponding controlled motor output torque drives EVs to track the desired vehicle reference speed for providing uninterrupted vehicle safe operation. The effectiveness of the overall sensor fault-tolerant speed tracking control is highlighted when an EV is subjected to disturbances like aerodynamic load force and road roughness using high-fidelity software package CarSim. Experiments with a 26-W, three-phase PMSM are presented to demonstrate the validity of the proposed fault-detection scheme.

Higher-Order Sliding Mode Observer for Speed and Position Estimation in PMSM

This paper presents a speed and position estimation method for the permanent magnet synchronous motor (PMSM) based on higher-order sliding mode (HOSM) observer. The back electromotive forces (EMFs) in the PMSM are treated as unknown inputs and are estimated with the HOSM observer without the need of low-pass filter and phase compensation modules. With the estimation of back EMFs, an accurate estimation of speed and rotor position can be obtained. Further, the proposed method completely eliminates chattering. Experimental results with a 26 W three-phase PMSM demonstrate the effectiveness of the proposed method.

Robust Fault-Tolerant Cruise Control of Electric Vehicles based on Second-order Sliding Mode Observer

This paper presents fault-tolerant cruise control of an electric vehicle based on the permanent magnet synchronous motor (PMSM). A higher order sliding mode (HOSM) observer is designed to estimate the unknown back electro motive forces (EMFs) in the plant dynamics. A finite-time smooth estimation without low-pass filtering is obtained and the chattering phenomenon is eliminated. With the estimated back EMFs, an accurate speed estimate of PMSM can be algebraically computed. The estimated speed is provided as a feedback whenever fault occurs in the measurement speed. The corresponding torque output drives the electric vehicle (train, car) to maintain the vehicle speed to a desired vehicle speed reference. Simulations in a high fidelity CarSim confirm the validity of the overall approach.

An induction motor sensor fault detection and isolation based on higher order sliding mode decoupled current controller

This paper presents a novel decoupled current-control method for induction motor (IM) based on higher order sliding mode (HOSM) controller. In the proposed scheme, the decoupled control of d - q currents does not require the knowledge of the speed. The HOSM controllers play the same role as the compensation voltages produced by a decoupling compensator. Based on this observation, the speed is estimated accurately through algebraic calculations by avoiding the low-pass filtering. The estimated speed is then employed for fault detection and isolation. Simulations on a 1/4-hp three-phase IM in the presence of noise highlights the performance of the proposed approach.

Sliding-Mode-Based Observer–Controller Structure for Fault-Resilient Control in DC Servomotors

This paper presents a robust observer–controller scheme for sensor fault-resilient control in dc servomotor drive-based applications (such as antennae control for satellite tracking, radio telescopes, and conveyor belt systems). In contrast to the earlier works on abrupt faults, this paper considers incipient sensor faults and detects using the higher order sliding mode (HOSM) observer, followed by a tracking controller, which maintains the acceptable drive performance. A robust output tracking controller based on fractional integral terminal sliding mode surface with HOSM terms is developed to ensure faster and finite-time convergence of the error trajectory. Moreover, various slopes of incipient faults are considered to analyze the detection delay, and switching strategy reconfigures the system with the estimated speed whenever the residual crosses the threshold. The closed-loop performance in the presence of most common faults (abrupt, incipient, and intermittent) is experimentally validated on a dc motor-based industrial mechatronic drives unit with belt-drive inertial load (which exhibits nonlinear friction, torque variations, and other disturbances).

Performance comparison of sliding mode observers for back EMFs based speed estimation in PMSM

This paper proposes a second-order high-speed sliding mode (SHSM) observer and compares the performance with the recent higher-order sliding mode (HOSM) observer for the problem of sensorless speed estimation in the permanent magnet synchronous motor (PMSM). In which, a sigmoid function is substituted for the signum function with a variable boundary layer. A SHSM observer is proposed to provide the estimation of back electro motive forces (EMFs) that are treated as unknown inputs in the PMSM model. An accurate speed estimate of PMSM can be algebraically computed with the estimated back EMFs. The chattering phenomenon, that is commonly found in the sliding mode observers is well-reduced by replacing signum function with the sigmoid function, in comparison to the HOSM observer. Simulation results show the effectiveness of the proposed SHSM speed estimation method in comparison to the earlier HOSM observer in terms of good accuracy and chattering phenomenon.

On-line detection of rotor eccentricity for PMSMs based on hall-effect field sensor measurements

Rotor eccentricity in permanent magnet synchronous motors (PMSMs) increases unbalanced magnetic pull and motor vibration resulting in accelerated aging of motor components. If eccentricity remains undetected, it can increase in severity, and increase the risk of stator-rotor contact, which causes forced outage of the motor and driven process. Detection of eccentricity currently relies on off-line testing and on-line vibration/current spectrum analysis, which are inconvenient or cannot provide reliable detection as they are influenced by other mechanical non-idealities in the motor or load. In this paper, the feasibility of using the signals from analog Hall-effect field sensors for detecting eccentricity is investigated. It is shown that Hall sensors already present in machines for motion control can be used for measuring the variation in the flux inside the motor due to eccentricity. 3-dimensional (3D) finite element analysis (FEA) and experimental results performed on an interior PMSM (IPMSM) show that the proposed method can provide sensitive and reliable detection of dynamic and mixed eccentricity with minimal hardware modifications.

Robust Sensors-Fault-Tolerance with Sliding Mode Estimation and Control for PMSM Drives

In general, permanent magnet synchronous motor (PMSM) drives require four sensors (one position, one dc-link voltage, and at least two current sensors) to obtain good dynamic control performance. If an unpredictable fault occurs in any of these sensors, the performance of the drive deteriorates or even becomes unstable. Most of the existing works are limited to fault diagnosis of one or two sensors due to complexity. Therefore, to provide a continuous drive operation regardless of any of the sensor faults, an advanced fault-tolerant control (FTC) scheme that comprises of higher order sliding mode (HOSM) based observers and controllers is proposed. Two HOSM observers and one Luenberger observer are designed to generate the respective residuals and provide the detection of all sensor faults. Moreover, HOSM controllers are developed to ensure finite-time convergence of the error trajectories after the fault reconfiguration. The proposed FTC scheme reduces the existing chattering phenomenon with good performance in terms of convergence speed and steady-state error. Evaluation results on a three-phase PMSM are presented to validate the effectiveness of the proposed FTC approach.

Robust control of DC motor drives using higher-order integral terminal sliding mode

The tracking performance of the industrial servo systems are highly affected by the inherent unstructured uncertainties (external disturbances, and/or unmodeled dynamics), which degrades the reliability of the drive. This paper presents a higher-order terminal sliding mode controller to achieve high-accuracy motion-tracking control of DC motor drives. Fractional integral terminal sliding mode (ITSM) manifold is selected to eliminate the reaching time to the sliding hyperplane, which provides fast tracking error convergence in finite-time. Further, super-twisting control is employed to reduce the chattering while compensating the unwanted unstructured uncertainties compared with the traditional sliding mode control. Experimental results on a DC motor-based industrial mechatronic drives unit (IMDU) with belt-drive load are presented to show the effectiveness of the proposed controller.

Second-order sliding mode based sensor fault-tolerant control of induction motor drives

This paper presents a fault-tolerant control method for induction motor (IM) based on higher order sliding mode (HOSM) observer. Traditional current control involves the regulation of the d-q synchronous reference frame currents with or without a decoupling compensator. The compensation voltages, which require speed and motor parameters cancel the coupling terms. When the speed is not available, this approach leads to a degraded performance of the controller. In the proposed scheme, a HOSM observer is designed to estimate the compensation voltages, which further estimates the motor speed through algebraic calculations. The estimated speed is then employed as feedback when speed sensor is faulty. Simulations on a 1/4-hp three-phase IM highlights the performance of the proposed approach.