Ola Carlson

Control Algorithms for a Fault-Tolerant PMSM Drive

This paper proposes control algorithms for a fault-tolerant permanent-magnet synchronous motor (PMSM) drive. In order to improve the reliability of the drive, an algorithm for achieving sensorless control that operates properly also in fault mode is proposed. Furthermore, it is shown how a closed-loop field-weakening controller needs to be modified in order to operate properly in fault mode. The application in mind is electric vehicle propulsion and the algorithms presented are verified with experimental results using an in-wheel PMSM. With the proposed modifications, the reliability of the drive can be increased.

Grid-Connected Integrated Battery Chargers in Vehicle Applications: Review and New Solution

For vehicles using grid power to charge the battery, traction circuit components are not engaged during the charging time, so there is a possibility to use them in the charger circuit to have an onboard integrated charger. The battery charger can be galvanically isolated or nonisolated from the grid. Different examples of isolated or nonisolated integrated chargers are reviewed and explained. Moreover, a novel isolated-high-power three-phase battery charger based on a split-phase permanent-magnet motor and its winding configuration is presented in this paper. The proposed charger is a bidirectional high-power charger with a unity power factor operation capability that has high efficiency.

Integrated chargers for EV's and PHEV's: examples and new solutions

The battery is an important component in an electric vehicle (EV) or a plug-in hybrid electric vehicle (PHEV) and it should be charged from the grid in a cost efficient, preferably fast and definitely safe way. The charger could be an on board or an off board charger. For an on board charger it is possible to use available hardware of the traction system, mainly the inverter and the electric motor, in the charger circuit. This is called an integrated charger. In this paper, different examples of integrated chargers are reviewed and explained. Additionally, other possible solutions of integrated chargers are described.

An Isolated High-Power Integrated Charger in Electrified-Vehicle Applications

For electric and hybrid vehicles that use grid power to charge the battery, traction circuit components are not normally engaged during the charging time; hence, there is a possibility of using the traction circuit components in the charger circuit to have an onboard integrated charger. An isolated high-power integrated charger based on a special electrical machine with a double set of stator windings is described. Through the reconfiguration of the motor stator windings in the charging mode, a six-terminal machine is achieved. The so-called motor/generator acts as an isolated three-phase power source after synchronization with the utility grid in the charging mode. This rotary isolated power source constitutes a three-phase boost rectifier (battery charger) with full utilization of the inverter. The motor windings are reconfigured by a relay-based switching device for the charging and traction modes. This paper presents the mathematical model of the motor/generator and explains the systems functionality for the traction and charging modes. Furthermore, the charger grid synchronization and charge control are described. Finally, the simulation results are presented for a practically designed system with a traction power of 25 kW and a possible charge power of 12.5 kW.

An improved speed and position estimator for salient permanent-magnet synchronous motors

An improved phase-locked-loop-type speed and position estimator for permanent-magnet synchronous motor (PMSM) drives is considered. Particular attention is put on salient-rotor PMSMs with fast mechanical dynamics. A method is presented, whereby significantly improved tracking is achieved. While saliency makes nominal-speed stability more difficult to guarantee (an analysis of this is presented), a benefit is that signal-injection methods can be used at low speeds for accurate position estimation, which is also included in the modified estimator.

Control algorithms for a fault-tolerant PMSM drive

This paper proposes control algorithms for a fault-tolerant permanent-magnet synchronous motor (PMSM) drive. In order to improve the reliability of the drive, an algorithm for achieving a sensorless control that operates properly also in fault mode is proposed. Furthermore, it is shown how a closed-loop field-weakening controller needs to be modified in order to operate properly in fault mode. Automotive applications are in mind and the algorithms presented are verified with experimental results using an in-wheel PMSM. With the proposed modifications, the reliability of the drive can be improved.

An Integrated 20-kW Motor Drive and Isolated Battery Charger for Plug-In Vehicles

For vehicles using grid power to charge the battery, traction circuit components are not normally engaged during the charging time, so there is a possibility to use them in the charger circuit to have an on-board integrated motor drive and battery charger. An isolated high-power three-phase integrated motor drive and charger based on a split-phase permanent magnet motor is presented in this paper. The motor winding connections are reversible by a relay-based switching device for traction and battery charging. In traction mode, the motor is a classical three-phase motor, but in charging mode it is a rotating isolating transformer providing a three-phase voltage source for the inverter to charge the battery. A mathematical model of the motor with six stator windings is presented for an arbitrary phase shift in windings. For the charging mode, the split-phase motor grid synchronization process and charge control are explained including the developed controller. A 20 -kW system is designed and implemented to verify the proper operation of the proposed system. Simulation and practical results are provided to show the system performance in terms of functionality, dynamic response, and efficiency. Moreover, some discussions, recommendations, and limitations are provided to give more practical insights.

Effects of Plug-in Electric Vehicles on distribution systems: A real case of Gothenburg

The electric power system is changing and, especially, the electrical distribution system will meet new features. One of the large changes is a transformation of the transportation sector with the use of electricity, with introduction of Plug-in Electric Vehicles (PEVs). This will pose new challenges and opportunities for the electric distribution companies. This paper analyzes the effects of PEVs charging on the local 400 V and 10 kV electric distribution systems in the city of Gothenburg, Sweden, using steady-state power flow analysis. Two different areas representing residential area and commercial area have been simulated for the worst-case scenario, which is simultaneous charging of all the vehicles during the peak load period. The number of PEVs used has been estimated based on the load level at each customer location. The study results have shown that overloading of lines and transformers would occur when simultaneous charging of the vehicles during the peak load period. There would, however, be no problem with the voltage drop at the customers location during PEVs charging. An iterative method is proposed to estimate the maximum number of possible vehicles charging in the distribution system without resulting in any congestion. This method is also applied when one of the feeders is on outage to ensure the N-1 reliability criterion.

An integrated charger for plug-in hybrid electric vehicles based on a special interior permanent magnet motor

For a plug-in hybrid electric vehicle (PHEV), the battery needs to be charged from the grid while the vehicle is parked. The traction system components are normally not engaged during the charging time so there is a possibility to use them in the charger system to develop an integrated charger. An innovative high power isolated three-phase bi-directional integrated charger with unit power factor operation is introduced for PHEVs based on a special configuration of the ac motor. The winding of the machine is re-arranged in charging mode to have a three-phase boost based high power battery charger. The system configuration, the device model (machine with multiple windings), traction and charging system functionality and charger control are presented in this paper.

Post-fault operation of fault-tolerant inverters for PMSM drives

This paper considers post-fault operation of permanent-magnet synchronous motor drives equipped with a fault-tolerant inverter. In post-fault mode, the faulted phase is isolated and the neutral point is connected either to an additional inverter leg or to the midpoint of the DC bus. Different methods of controlling the neutral point voltage are presented and compared. Furthermore, operation without a position sensor (i.e., sensorless control) is considered and a modification to an estimator previously reported in the literature is proposed in order to take into account the effect of the asymmetry introduced due to the isolation of the faulted phase in post-fault mode. Simulations and experimental results are provided to support the theory and demonstrate the practical impact of the modifications proposed