Sensorless control of AC machines for low and zero speed operation without additional test signal injection

This work considers the sensorless control of AC machines for the low and zero speed operation range. Two novel techniques have been developed that use the inherit nature of the inverter PWM to estimate the rotor position of the machine. The inherent back EMF and the saliency of AC machines can be utilized to identify the rotor/flux position. The zero vector current derivative (ZVCD) technique for permanent magnet synchronous machines (PMSM) utilizes both of these effects. No additional test signals are injected into the machine and the difficulty in sensing the machine terminal voltage at low speed is eased. Only three standard current transducers are used in the drive system. For the position/ speed estimator only the machine current derivative during the relatively long (at low speed) zero voltage vectors is used for obtaining the rotor position. Practical results show the operation of the drive at several torque and speed conditions including stand still. A further method has been developed for the sensorless control of induction machines. The high frequency harmonics present in a PWM inverter drive system can be used to detect an equivalent impendence saliency that shows modulation due to rotor/ flux position saliency. The proposed method focuses particularly on the extraction of spatial saliency modulation due to rotor bar slotting effect, which can be used to determine the mechanical rotor position. No additional signal injection is required; the method simply employs some of the inherent PWM carrier harmonics

Sensorless control of AC machines for low and zero speed operation without additional test signal injection

This work considers the sensorless control of AC machines for the low and zero speed operation range. Two novel techniques have been developed that use the inherit nature of the inverter PWM to estimate the rotor position of the machine. The inherent back EMF and the saliency of AC machines can be utilized to identify the rotor/flux position. The zero vector current derivative (ZVCD) technique for permanent magnet synchronous machines (PMSM) utilizes both of these effects. No additional test signals are injected into the machine and the difficulty in sensing the machine terminal voltage at low speed is eased. Only three standard current transducers are used in the drive system. For the position/ speed estimator only the machine current derivative during the relatively long (at low speed) zero voltage vectors is used for obtaining the rotor position. Practical results show the operation of the drive at several torque and speed conditions including stand still. A further method has been developed for the sensorless control of induction machines. The high frequency harmonics present in a PWM inverter drive system can be used to detect an equivalent impendence saliency that shows modulation due to rotor/ flux position saliency. The proposed method focuses particularly on the extraction of spatial saliency modulation due to rotor bar slotting effect, which can be used to determine the mechanical rotor position. No additional signal injection is required; the method simply employs some of the inherent PWM carrier harmonics

A review of saliency-based sensorless control methods for alternating current machines

Operation of model-based sensorless control of Alternating Current machines at low and zero speeds is unreliable and can fail. To overcome the limitations of sensorless control at low speeds, several alternative techniques have been developed to estimate speed and position. These are mainly based on detecting machine saliencies by measuring the response of the current to some form of voltage injection. This paper discusses injection methods, machine saliencies, and techniques used to extract speed and position that are applicable to both induction machines and permanent magnet synchronous motors.peer-reviewe

On the range equation for a hybrid-electric aircraft

This paper proposes a new range equation for hybrid-electric aircraft. The paper revisits the theory of the range equation for a hybrid-electric aircraft with constant power split published earlier in the literature and proposes a new efficiency-based definition of the degree of hybridization (φ), one which includes the efficiencies of the electric or fuel-powered drivetrain. The paper shows that the efficiencies of the respective drivetrains play a significant role in the range estimation of the hybrid-electric aircraft. The paper makes use of a case study to show the relationship between battery energy density, powertrain efficiency and modification in the definition of the degree of hybridization φ with aircraft range. We show that for every aircraft design, there is a battery energy density threshold, for which the aircraft range becomes independent of the degree of hybridization. Below this threshold, the range decreases with an increase in the degree of hybridization. Conversely, beyond this threshold, the aircraft range increases with the degree of hybridization. Our study finds that the new definition of φ has shifted this threshold significantly upwards compared to earlier publications in the literature. This makes the design of an aircraft with a high degree of hybridization less optimistic.peer-reviewe

Space modulation profile modelling for steer-by-wire SMPMSM

This paper presents a sensorless estimation algorithm for steer-by-wire applications based on the injection of a high-frequency rotating voltage. Enhancement to the basic sensorless algorithm through SMP look-up tables is proposed. The improved observer was simulated in MATLAB for a 12 V RMS 400 W permanent magnet synchronous machine (PMSM).peer-reviewe

Torque feedback for steer-by-wire systems with rotor flux oriented PMSM

This paper presents the design and implementation of a current controlled Rotor Flux Oriented PMSM for automotive steer-by-wire applications. The development of a realistic torque feedback reference is carried out by actual monitoring of a commercial vehicle. The paper shall discuss the torque dynamics of the PMSM drive with respect to position demands replicating a driver at the handwheel. A PowerPoint presentation by same authors about this subject is included in this section.peer-reviewe

Sensorless position control of a PMSM for steer-by-wire applications

This article shall present the design and implementation of a MATLAB/Simulink model for the sensorless control of a PMSM in a steer-by-wire application. Simulation results for position, speed and current loops in a closed-loop sensorless mode are shown. The sensorless method is based on the tracking of saliencies by high frequency injection. In addition, a presentation on same subject is presented by the authors.peer-reviewe

Sensorless position tracking for steer-by-wire applications

This paper shall present the design, simulation and implementation of a sensorless observer for three-phase permanent magnet synchronous machines which can be used for automotive steer-by-wire applications. It shall be shown that the observer has sufficient bandwidth to track steering transients enabling the sensorless speed/position estimates to be used for backup in case of encoder failure. The sensorless method is based on a high frequency injection approach which estimates speed/position from machine saliencies. The simulation/experimental environments were designed so as to emulate actual steering conditions studied as part of this research project.Additionally, a PowerPoint presentation on Sensorless Position Tracking for Steer-by-Wire Applications by the authors is included in this section.peer-reviewe

A review of sensorless control in induction machines using HF injection, test vectors and PWM harmonics

This paper gives a review of sensorless methods developed for ac drives’ operation at very low and zero speed. The sensorless drives presented in this paper use reluctance spatial anisotropy to track the mechanical rotor position, allowing the use of vector control. To extract the position information additional test signals in form of active vector pulses or continuous high frequency signals are injected into the machine. This paper also presents a technique which does not make use of additional test signals, but only components resulting from the inverter PWM pattern. Practical results show that with all reviewed methods sensorless vector control at very low and zero speed is possible. However, disturbances (eg. coming from the inverter or magnetic saturation) affect the position signal significantly and require appropriate compensation.peer-reviewe

Sensorless control of AC machines for low and zero speed operation without additional test signal injection

This work considers the sensorless control of AC machines for the low and zero speed operation range. Two novel techniques have been developed that use the inherit nature of the inverter PWM to estimate the rotor position of the machine. The inherent back EMF and the saliency of AC machines can be utilized to identify the rotor/flux position. The zero vector current derivative (ZVCD) technique for permanent magnet synchronous machines (PMSM) utilizes both of these effects. No additional test signals are injected into the machine and the difficulty in sensing the machine terminal voltage at low speed is eased. Only three standard current transducers are used in the drive system. For the position/ speed estimator only the machine current derivative during the relatively long (at low speed) zero voltage vectors is used for obtaining the rotor position. Practical results show the operation of the drive at several torque and speed conditions including stand still. A further method has been developed for the sensorless control of induction machines. The high frequency harmonics present in a PWM inverter drive system can be used to detect an equivalent impendence saliency that shows modulation due to rotor/ flux position saliency. The proposed method focuses particularly on the extraction of spatial saliency modulation due to rotor bar slotting effect, which can be used to determine the mechanical rotor position. No additional signal injection is required; the method simply employs some of the inherent PWM carrier harmonics.EThOS - Electronic Theses Online ServiceGBUnited Kingdo