Research Areas

Research Area: Transportation Drives and Systems

Magnetic levitation systems for high speed ground transportation

Closed-loop track for T-shaped LIM 
 

The research concerns the analysis of the vertical dynamics of an electrodynamic levitation system using superconducting coils and a passive damping system. The vertical dynamics of the levitation system is described by the motion equation and the electromagnetic transient equations. In high speed magnetically levitated vehicles, passive damping system usually doesn't provide the required ride quality. Then the damping effect on the mechanical oscillation of the vehicle should be improved by using an additional active damping system. There may be a considerable advantage in using an active system in conjunction with a passive damping system. In the levitation system analysed the two effects are obtained by controlling the current in one of the coils of the damping system. 


Research Area: High Performance Drives

Vector Control of Induction Motors

Laboratory view
 

The aim of the research is the analysis and the implementation of a vector control technique for induction motors which utilises stator flux components as controlled variables. The control strategy needs neither rotor resistance nor coordinate transformation based on the rotor flux position, leading to a high performance drive using a simple control scheme. The method is based on direct control of torque and stator flux. These quantities can be controlled independently by selecting a proper configuration of the inverter switches. The selection is made according to the instantaneous errors in torque and flux. Each selection strategy affects the drive behaviour in terms of torque and current ripple, switching frequency and regenerative capability. In addition it should be noted that using some of the possible switching strategy, undesired flux weakening has been observed. The aim of this research is to analyse the effects of the different switching strategies on the behaviour of direct torque control drives. 
 
 
 
 
 
 
 


Research Area: Electromechanical System Design

Eelectromagnetic/thermal design and simulation of electric motors and electromagnetic structures. (PDF, 810 kB)
 

Linear actuators

DC PM linear motor application
 

The linear actuators are increasingly employed as direct actuators in servo systems replacing the more conventional mechanical systems. The use of permanent magnets on the slider offers several advantages associated with the absence of electrical connections and heating effects due to copper losses. In addition, the use of a slotless armature results in a simplified construction. The design of these linear actuators is optimised for maximum force to total mass ratio and for maximum force to moving mass ratio. In order to analyse the dynamic behaviour a mathematical model based on a simplified field analysis is developed. Numerical simulations of the step response of a positioning servo system are now under investigation.
 
 
 
 
 
 
 
 
 
 
 
 

Research Area: Power Converters

Vector Modulated Matrix Converters


Direct ac to ac converters have received considerable attention with the progress of power devices. The matrix converters have advantages over traditional rectifier-inverter type frequency changers such as: four-quadrant operation capability, sinusoidal input and output waveforms with minimum harmonic distortion, controllable power factor, minimal energy storage requirements. In this research a new control algorithm based on space vector modulation theory which allows sinusoidal input and output waveforms with unity input power factor, is investigated. The space vector modulation approach has advantages with respect to the traditional modulation technique: immediate comprehension of the required commutation process, simplified control algorithm, maximum voltage transfer without adding third harmonic components, no synchronisation requirements with input voltage waveforms. Up to now little attention has been paid to the use of matrix converter under unbalanced supply voltages. The proposed control technique allows good performance to be obtained even under unbalanced supply voltages, avoiding the introduction of low order harmonics.



 

Research Area: Electric Vehicles

Electric "GIG"

Places like small islands, natural parks or historical city centers are visited by tourists mainly during the summer season. Until now, several services like shuttle rides and sight-seeing tours are widely performed using Internal Combustion Engine vehicles with a modified body.

To improve the environmental quality of these places the vehicle requirements may be summarized as follows: low emission of exhausts and noise, small overall dimensions, large load capability, wide sight for passengers, good climbing performance, high autonomy and inexpensive maintenance. The Electric Gig satisfies all these stringent requirements. This vehicle is based primarily on the use of the state of the art technologies for batteries and drives. Furthermore, a particular shape for the body has been adopted. The characteristics of the proposed EV called Electric Gig are: 3-phase water cooled induction motor, electric drive based on a sensorless Stator Flux Vector Control technique, Nickel-Sodium-chloride battery pack, efficient fitting of electric parts in the chassis and light convertible body.
The Electric Gig has been assembled by Micro-Vett S.r.l. on the basis of a chassis of the Porter Piaggio. The design of the body has been reviewed by the Italian car designer “Vernagallo”. Up to seven passengers can accommodate on the vehicle. The electric motor has been directly coupled to the differential gearbox driving the rear wheels. The battery pack is located under the flatcar avoiding the loss of payload volume availability. The new type of battery employed (Ni-Na-Cl) allows a range above 100 Km.  The power conversion unit is also located in the flatcar in the rear part of the vehicle.
The high performance of the vehicle in terms of maximum speed, maximum climbing slope, and autonomy as well as the winning body design, should satisfies the market requirement providing the basis for the industrialization of this product.

 
 

ELECTRIC GIC - Technical Specifications
 
Chassis Porter Piaggio
Electrical equipment Micro-Vett S.r.l.
Body Open
Seats 2+4

Motor
Type   3-phase induction motor - liquid cooled
Rated Power  17,5 kW (23.7 CV) @ 2400 rpm
Rated Voltage  165 V
Rated Frequency 78 Hz
Rated Torque  70 Nm (7,13 Kgm)
Max. Speed  4500 rpm

Inverter
Control Technique Stator Flux Vector Control (sensorless)
Max. Current 240 A
Max. Frequency  150Hz
Batteries  
Type ZEBRA Nickel Sodium Chloride
Capacity 60 Ah
Rated Voltage  296 V
Stored Energy 17,5 KWh
Standard Charge 10 hours
Fast Charge  2 hours

Performance
Max speed  70 Km/h
Urban cycle range  100 Km
Max slope  16 %
Plain road acceleration  1.6 m/s2

"VIVI"
Research Project for developing an innovative electric vehicle for disables which allows an independent way of life.



 
 
 
 
Electric Motor Three-phase Induction Motor SL1
Rated Power 3800 W
Rated Voltage 56 V
Rated Frequency 70 Hz
Pole number 4
Rated speed 2000 rpm
Maximum speed 6000
Efficiency 85%
Air-cooled IP67

 

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