A review on electrochemical double-layer capacitors

This paper proposes a simple but effective method of electric brake with energy regeneration for a brushless DC motor of an electric vehicle (EV). During the braking period, the proposed method only changes the switching sequence of the inverter to control the inverse torque so that the braking energy will return to the battery. Compared with the presented methods, the proposed solution simultaneously achieves dual goals of the electric brake and the energy regeneration without using additional converter, ultracapacitor, or complex winding-changeover technique. Since the braking kinetic energy is converted into the electrical energy and then returns to the battery, the energy regeneration could increase the driving range of an EV. In addition to the braking period, the duration of release throttle is also included in the energy-regenerative mechanism such that the EV is similar to engine vehicles having the engine brake. Therefore, the electric brake can improve rider's comfort and enhance the EV's safety. Finally, the feasibility of the proposed method is demonstrated by experimental results. It shows that the driving range of the EV could be increased to about 16.2%.

A Cost-Effective Method of Electric Brake With Energy Regeneration for Electric Vehicles

This manuscript focuses on a novel actively controlled hybrid magnetic battery/ultracapacitor based energy storage system (ESS) for vehicular propulsion systems. A stand-alone battery system might not be sufficient to satisfy peak power demand and transient load variations in hybrid and plug-in hybrid electric vehicles (HEV, PHEV). Active battery/ultracapacitor hybrid ESS provides a better solution in terms of efficient power management and control flexibility. Moreover, the voltage of the battery pack can be selected to be different than that of the ultracapacitor, which will result in flexibility of design as well as cost and size reduction of the battery pack. In addition, the ultracapacitor bank can supply or recapture a large burst of power and it can be used with high C-rates. Hence, the battery is not subjected to supply peak and sharp power variations, and the stress on the battery will be reduced and the battery lifetime would be increased. Utilizing ultracapacitor results in effective capturing of the braking energy, especially in sudden braking conditions.

A Novel Integrated Magnetic Structure Based DC/DC Converter for Hybrid Battery/Ultracapacitor Energy Storage Systems

This article presents the impact of the performance of an FC and control strategies on the benefits of hybridization of fuel cell/supercapacitor hybrid sources for vehicle applications. Then, the storage device can complement the main source to produce the compatibility and performance characteristics needed in a load. The studies of two hybrid power systems for vehicle applications, FC/battery and FC/supercapacitor hybrid power sources, are explained. Experimental results with small-scale devices (a PEMFC of 500 W, 40 A, and 13 V; a lead-xicid battery module of 33 Ah and 48 V; and a supercapacitor module of 292 F, 500 A, and 30 V) in laboratory will illustrate the performance of the system during motor-drive cycles.

The benefits of hybridization

This paper presents a sensorless control system for an electric-vehicle (EV) induction-motor (IM) drive embedded with an indirect vector controller and a fixed-boundary-layer sliding-mode (FBLSM) observer. No speed or even voltage measurements are required. This novel FBLSM observer could accurately estimate the speed and flux even without known load torque, where chattering on estimations due to switching functions in normal sliding-mode observers is almost completely eliminated. The proof of observability in a wide speed range (including very low speeds) is given. The indirect vector controller with feedforward compensation is responsible for tracking motor speed or torque commands, which manages to accelerate algorithm processing and to enhance transient performance. The experimental results based on a high-power driver-load motor configuration validate the accuracy of the observer and the dynamical performance of the controller under multitrapezoidal speed and vehicle driving cycle torque-speed commands, taking into consideration unexpected parameter disturbances .

Sensorless Induction Motor Drive Using Indirect Vector Controller and Sliding-Mode Observer for Electric Vehicles

A novel electric gearshift with ultracapacitors is designed for the power train of a directly driven electric vehicle. The power train consists of two major subsystems: electric propulsion and energy source. The electric propulsion subsystem is composed of a dedicated wheel motor and its drive; the energy source subsystem is equipped with a stack of lead-acid batteries and ultracapacitor cells. This electric gearshift combines different parallel and serial connections of batteries, motor windings, and ultracapacitors to accommodate various driving patterns in the permissible range of speed and torque. A control core, which is realized by a field-programmable gate array, is employed to manage the energy source and direct optimal propulsion to extend the speed range of constant power, and thereby improve vehicle performance in terms of efficiency, acceleration, and driving range.

An Electric Gearshift With Ultracapacitors for the Power Train of an Electric Vehicle With a Directly Driven Wheel Motor

A system and method of electric gearshift and an automobile using this system and method are disclosed. A motor is driven according to a gearshift policy for optimizing energy consumption and system performance. A battery set and a capacitor set are used to provide or store electric energy for driving the motor. A control unit control to switch between series and parallel connections in the battery set, the capacitor set and coils of the motor. Gearshift is performed according to a signal of acceleration or braking, rotational speed of the motor and a predetermined gearshift policy.

Kun-Chang Kuo

Papers

An Electric Gearshift With Ultracapacitors for the Power Train of an Electric Vehicle With a Directly Driven Wheel Motor

A system and method of electric gear-shift