http://ieeexplore.ieee.org/iel5/5610941/5624686/05624745.pdf

Power electronics

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.

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

Six-step operation has many advantages in permanent-magnet synchronous machine (PMSM) drives such as maximum power utilization and widened flux-weakening region. However, due to the maximum utilization of inverter output, saturation of current regulator makes it difficult to maintain instantaneous current control capability. Accordingly, in most of conventional research studies, the six-step operation has been implemented by voltage angle control without current regulation, whose dynamic performance is quite unsatisfactory. This paper proposes a control scheme for the six-step operation of PMSM with enhanced dynamic performance of current control. By collaborative operation of dynamic overmodulation, flux weakening, and a technique for enhanced dynamic performance, the six-step operation is realized without losing instantaneous current control capability. Simulations and experiments are carried out to verify the effectiveness of the proposed control scheme. The experimental results show 17% extension of the constant torque region and 27% enhancement of torque capability at three times of the base speed.

Six-Step Operation of PMSM With Instantaneous Current Control

This research proposes a procedure that maps a PMSM torque request onto optimal state (current) references. Combining the procedure with a dynamic (current) controller yields a torque controller. The maximum torque per ampere (MTPA) criterion is used to minimize conduction and switching losses. This research extends the concept to field-weakening operation to obtain high efficiency at any machine speed. The resulting constrained MTPA criterion is formalized as an optimization problem. Since it is difficult to solve directly, the maximum and intersection torque subproblems are identified. An algorithm is obtained that maps a torque onto an optimal state reference, and it is sufficiently efficient for real-time implementation. This method is compatible with a variety of state (current) controllers with/without PWM, SPM and IPM machines with saliency and reverse saliency, and a variable dc-link voltage. The proposed procedure relies on a sufficiently accurate torque model that may not be provided using rated machine parameters. Thus, an approach to compute locally optimized machine parameters is proposed that takes magnetic saturation into account. The concept is developed on a software-in-the-loop platform and evaluated on an experimental test bench.

Optimal State Reference Computation With Constrained MTPA Criterion for PM Motor Drives

A concept of an integrated and distributed inverter for switched reluctance machines is introduced. The application at hand is an outer-rotor direct drive designed for railway traction applications. A five-phase switched reluctance machine was developed and is used to demonstrate the function of the integrated and distributed inverter. The distribution is achieved by supplying each phase coil with its own modular inverter. Each inverter module is placed evenly around the end of the stator stack next to its dedicated coil. This increases the redundancy of the drive significantly. The likelihood of phase-to-phase faults is reduced, because no overlapping end-turns are necessary. Also, the integration of machine and inverter is simplified, because the semiconductors can be evenly distributed around the machine. The concept reduces the amount of terminals between drive and vehicle to communication, power supply, and cooling, independent of the number of machine phases. With the integrated and distributed inverter new control strategies can be developed to influence machine vibration and radiated noise. In this paper, the design of the prototype, the direct torque control of the five-phase machine, and the behavior in the case of a fault inside a module is analyzed.

Development and Control of an Integrated and Distributed Inverter for a Fault Tolerant Five-Phase Switched Reluctance Traction Drive

In electric and hybrid-electric vehicle applications, power electronic converters are used to couple the traction machine with the battery stack. The simplest topology consists of an inverter between the battery stack and the machine. In an often discussed alternative, a DC-DC converter is used to feed the traction machine with a higher and stable voltage level. This paper deals with the differences which arise in terms of the applied control strategy and identifies operating regions of improved efficiency.

Advantages of a variable DC-link voltage by using a DC-DC converter in hybrid-electric vehicles

A universal and modular approach for synthesizing electromagnetically excited vibrations in electrical machines is presented. The synthesis process uses force responses, i.e., the normalized structural vibration responses for a machine's generic set of force excitation shapes. The responses are superposed after scaling by the operating point dependent force excitation amplitudes. This leads to a computationally efficient process. It allows to use detailed structural 3-D models and to synthesize the vibrations in the entire operating range of the machine. For validation, measured and synthesized vibration spectrograms of a run-up test of an interior permanent magnet traction motor are presented.

Vibration Synthesis for Electrical Machines Based on Force Response Superposition

With the aim to asses power electronic architectures for electric vehicles, modeling of power electronics is discussed in this paper. Drive train topologies are introduced, the investigated power electronic components are described, and the modeling process is discussed. On the basis of an example scenario, selected simulation results are presented.

Power electronic architectures for electric vehicles

In hybrid and electrical vehicles the electric components have to be optimized to their limits The voltage which is delivered by a high-voltage battery should be used fully by the machine This paper describes the influence of the dc-link voltage on the efficiency and the operating limits of the electric system For the optimal usage of the dc-link voltage, the converter control has to be extended to the six-step mode This paper starts with a short introduction describing the electrical components of the developed hybrid vehicle Afterwards the restrictions due to the voltage limit of the high voltage battery are analyzed A field oriented control (FOC) is chosen to achieve a high performance control system However, the field oriented control is not capable to fully utilize the available dc-link voltage As will be shown it is possible to improve the control strategy of the electrical machine Especially in applications with limited dc-link voltage and high power density, the new control strategy leads to a better utilization and a higher efficiency of the electrical system

Maximum DC-link voltage utilization for optimal operation of IPMSM

Energy storage devices have become an important part of many mobile applications, such as conventional, electric or hybrid electric vehicles. For an optimal and efficient system design, simulation models have become an inevitable tool. Accuracy over a wide range of operating conditions is very important. However, electrochemical storage devices are strongly nonlinear and often show inhomogeneous current distribution leading to performance and lifetime limitations.

Timo Schoenen

Papers

Advantages of a variable DC-link voltage by using a DC-DC converter in hybrid-electric vehicles

Vibration Synthesis for Electrical Machines Based on Force Response Superposition

Power electronic architectures for electric vehicles

Maximum DC-link voltage utilization for optimal operation of IPMSM

Efficient battery models for the design of EV drive trains