A. Lidozzi

Common and differential mode EMI filters for power electronics

Electromagnetic interference (EMI) has become in recent years a great concern to deal with, in every kind of application and especially in power electronics. As a consequence of international and national standards requirements, the insertion of an EMI filter in power electronic converters assembly is today a common practise. In this paper the EMI characterization of the power conversion system that manages the power flows between the generation and storage units of a hybrid vehicle is presented. With the purpose of reducing conducted emissions and designing a proper EMI filter, the overall noise has been separated into its common mode (CM) and differential mode (DM) components. Experimental results underline the importance of considering CM and DM noises separately in order to minimize the filter components count and size.

Thermal regulation as control reference in electric drives

Recognition of technical specification for electric drives thermal sizing is quite challenging in both transportation applications and distributed generating systems. In particular, components of electric drives for hybrid farm equipment, like tractors as well large combines, are often overstressed because of either high ambient temperature or overload working condition. The electric drive components are mainly chosen with reference to average power and energy considerations; however, overload operating conditions can occur for time durations not established in advance, as well quite unpredictable thermal conditions are associated to environment related to diesel engines in hybrid configurations. For this reason, it is convenient to provide the control system of the electric drive unit with a sort of thermal regulation of the electric and electronic equipment, which can be achieved by adjusting some operating conditions, as dc-link voltage, modulation strategy and switching frequency, in order to reduce thermal stress on either power electronic devices or electrical machines windings.

EMI characterization and communication aspects for power electronics in hybrid vehicles

paper deals with the EMI (electromagnetic interference) characterization and the communication aspects for the power electronics hardware devoted to control the traction power flows in hybrid vehicles. The power conversion system related to the particular vehicle generation and storage units will be analyzed from both the functional (control and communication) and EMI point of view. The control structure and the communication architecture will be described and the use of a bus- multiplexed structure for the communication interface between the power converters has been investigated. In particular the CAN (controller area network) standard has been selected in order to evaluate the achieved improvement in efficiency. An extensive experimental test campaign (conducted emission) is carried out in order to evaluate the overall EMI performance of the single power converter and, in particular, to estimate which is the contribution to the system emission levels due to auxiliaries as the control platform and the related electronic boards (measures acquisition, filtering, driving circuits and power supply distribution network).

Multiple resonant controller with load-adaptive phase compensation capabilities

The use of voltage source inverters (VSI) in microgrid stand-alone applications needs the accurate control of the filter output voltages. Resonant controllers represent a good tradeoff between implementation issues and control performance. However, the un-known nature and size of connected loads, from the control point of view, affect the dynamic control behavior and may reduce the effectiveness of the harmonic controllers. The proposed multiple resonant controller is on-line tuned according to the designed filter and load behavior which may change during the converter operation. In this manner, several harmonic compensators can be placed in the loop to achieve better output voltage waveform, (i.e. lower total harmonic distortion).

Control technique and operation strategy of PM generators in hybrid vehicles

The paper depicts in depth a generation system based on an internal combustion engine which is coupled to a permanent magnet synchronous motor. The system is configured and remotely controlled by means of the controller area network standard. Software supervisor has been developed using LabView, which has been interfaced to the generation system control unit by the CAN protocol. Two different generation units and power train architectures are presented with respect to two different hybrid vehicles.

Three-phase Z-source power supply design and dynamic modeling

Z-source converter configurations make possible to overcome intrinsic limits present in conventional both ac-dc and dc-ac converters. A typical three-phase inverter can not supply output voltages greater than the voltages at its input; at the same manner, a typical three-phase boost-rectifier can not supply output voltages lower than input voltages. Using Z-source topology permits to overcome both these limits. In fact, a Z-source boost-rectifier can theoretically step-down the output voltage to any desired value. Additionally, it presents intrinsic immunity to shoot-through states, relaying to improved reliability of the entire system. In this paper, attention is focused on the mathematical modeling of a three-phase Z-source boost-rectifier for PFC power supply applications; where, using of such a topology as first-stage converter allows to design the second-stage converters with the same voltage constraints of single-phase units.

Integral-resonant voltage control for three-phase four-leg voltage source inverters

This paper deals with a newly-conceived voltage control method for three-phase four-leg voltage source inverters (VSI) which are being required in autonomous power generating units devoted to supply both three-phase and single-phase electrical loads in four-wire electric power distribution systems. In order to deal with VSI operating conditions providing three-phase voltage supply of both unbalanced loads and non-linear loads, an Integral + Resonant (I+R) voltage control structure is discussed and experimentally verified by means of a 25 kVA rated power converter prototype. It is shown that the proposed voltage control allows simplifying the overall control configuration, achieving zero-overhead power factor regulation and fast compensation of load unbalances. Further to that, a complete current limiting strategy is described and tested under different load conditions.

Multi Input Power Electronic Converter

The University of Rome “ROMA TRE” and ENEA, the Italian National Agency for New Technologies, Energy and the Environment, have jointly developed and tested a Multi Input Power Electronic Converter (MIPEC) that is able to manage the bi-directional electric power flowing from a maximum of three different sources to a common output.