Francisco J. Perez-Pinal

Stability of an Electric Differential for Traction Applications

The use of an electric differential (ED) constitutes a technological advance in vehicle design along the concept of more electric vehicles (MEVs). EDs have the advantage of replacing loose and heavy mechanical differentials and transmissions with lighter and smaller electric motors directly coupled to the wheels via a single gear or an in-wheel motor. To date, EDs have been proposed for two- and four-wheeled vehicles. Despite its long reported success and possible advantages in terms of flexibility and direct torque control of the wheels during cornering and risky maneuvers, the ED has several problems that have limited its applicability, for instance, an increment of control loops and an increase of computational effort. Therefore, the main purpose of this paper is to present a simple and easy-to-implement ED that ensures both reliability and good path tracking. The proposed strategy has the advantage of being linear and, therefore, easy to implement. Furthermore, a rigorous proof of stability is presented, and connections with other controllers are discussed. Features and advantages of the proposed scheme are illustrated via numerical simulations in a 4-kW system, which is able to handle 500-kg mass and deliver peak power up to 10 kW during transit periods.

Relative coupling strategy

Multi-motor arrangements have grown as an important field in the manufacturing process where high-performance applications that are able to achieve precise control of position, speed, acceleration, and deceleration are required. Several approaches exist for such synchronisation control all of them with the main aim to synchronize multiple machine axes and to emulate the actions of the mechanism they replace. However, so far little work has been done in the relative speed and position error between axes during the start-up, shutdown conditions and under load impacts on any motor. This paper present a novel multi-motor synchronisation strategy called relative coupled strategy, which can be easily applied into a real industrial environment. This novel approach is specifically compared with the electronic (virtual) line shaft. Results are presented showing the ability of the novel and current strategies to cope with different load conditions.

Improvement of the electronic line-shafting

Electronic (virtual) line shaft has shown its feasibilities and improvement in multimotor arrangements where high-performance applications that are able to achieve precise control of position, speed, acceleration, and deceleration are required. Several studies have been done in order to increase its performance and productivity. However the relative angle between multi axes and a procedure to avoid the virtual line has not been discussed. Therefore, this paper develops a commission procedure to avoid the virtual line in the classical electronic line shaft and it presents a novel array, which lets to reach an equal speed and zero position error between axis during the startup, shutdown conditions and under load impacts on any motor.

Multi-objective control for cascade boost converter with single active switch

A n-stage cascaded boost converter connected with a single active switch is usually used in applications with high conversion ratio. It has been reported that the dynamic of the transfer function output-voltage-to-duty cycle related with the first inductor is minimum phase and the second, third or n inductor current has right-hand side (RHS) zeros; as a result, it is obtained and increment of complexity in the controller design. In this paper a hybrid multi-objective controller is proposed, which can use any inductor current in the converter as a feedback and overcome the drawback of RHS; meanwhile it achieves an excellent output voltage control under disturbances either from supply voltage, load voltage or other perturbations. Experimental results are given for a 100W three stage cascade boost converter with one single active switch taken as a benchmark.

Electric Differential for Traction Applications

The use of electric differential constitutes a technological advance of vehicle design along the concept of more electric vehicles. Electric differentials have the advantages of replacing loosy, heavy and inefficient mechanical transmission and mechanical differential with a more efficient, light and small electric motors directly coupled to the wheels via a single gear or an in-wheel motor. To date, electric differentials have been proposed for two and four wheeled vehicles. Despite its long reported success and possible advantages in terms of flexibility and direct torque control of the wheels during cornering and risky manoeuvres. Electric differential has several problems in practical applications; for instance, an increment of control loops, increase of computational effort and slip. Therefore, the main purpose of this paper is to present a simple and easy to implement electric differential. The proposed strategy has the advantages of having a linear model and a straightforward implementation. Numerical simulations using Matlab-Simulink are shown for a 4 kW system which is able to handle 500 kg mass and deliver peak power up to 10 kW during transit periods.

Hybrid control technique applied in a FC-SC electric vehicle platform

A Fuel Cell-Supercapacitor Electric Vehicle (FC-SC-EV) with only one power converter generally uses the FC as an average power unit and the SC as a peak power unit. This array requires operating the power converter linked to the FC in operation regions rather than single operation point; as a result traditional averaged modeling and control methods are no longer valid. In this paper, a hybrid control technique is proposed to control the power converter, which is cable to work in operation regions and it can use any inductor current in the converter as a feedback; meanwhile it achieves an excellent output voltage control under disturbances either from supply voltage, load voltage or other perturbations. Experimental results are given for a 1kW Nexa® power module and interleaved boost converter taken as a benchmark.

Switched control of interleaved converters

In this paper, a time varying switching control of interleaved converters is proposed. The controller has the feature of being simple and it is able to guarantee global voltage regulation. The controller is based on the piece-continuous model of the converter and it works by switching between performance surfaces that depends on the state vector. The switching surfaces are chosen differently for each cell of the interleaved converter in order to guarantee, both maximum current and voltage ripple. Furthermore, a given phase between current signals can also be guaranteed. The switched control is illustrated in a 2-cell 2kw boost converter: however, it can be applied directly in any interleaved converter independently of the number of cells.

Hybrid multi-objective control of DC-DC converters

The highly need of flexibility and more robust controllers in areas such as motor controllers, renewable energy, and power electronics have opened the niche for applying and developing a new family of more active controllers such as: fuzzy, linear quadratic, passivity, pulse adjustment, etc. All these controllers are able to work in operations regions rather than at a single operation point and they make use, for practical implementation purposes, at least one DSP or FPGA. Following this trend, the main purpose of this work is to propose a new hybrid controller, which is able to work in several operation regions while having the feature of being of simple structure and easy to implement. In addition, the proposed strategy has several advantages that makes it attractive, (i) the controller is able to solve a multi-objective problem (i.e. voltage regulation and current limitation), (ii) it is robust against parameter uncertainty (i.e. the controller does not make use of knowledge of system parameters), and (iii) the controller operates at constant frequency. Controller description, numerical simulations and experimental work in a boost converter are presented.