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This paper deals with a newly conceived combined control topology. Deadbeat and repetitive controllers are proposed to operate jointly in a four-leg voltage-source inverter for stand-alone applications. In such a mode of operation, a dedicated controller has to regulate the inverter output voltages, which are measured at the output of the power filter. In the proposed combined control, the deadbeat rapidly compensates the output voltage variations due to load changes, whereas the repetitive control provides the required harmonic compensation capabilities that are mandatory to comply with the standards when balanced and unbalanced nonlinear loads have to be fed. As a consequence, high dynamic performance is assured, as well as harmonics in the output voltages are almost absent. In fact, the achieved experimental tests have verified that resulting output voltage total harmonic distortion is around 0.5%, and in the case of highly unbalanced and nonlinear loads, compensating also the distortion introduced by the switches’ deadtime.

A novel solution to high efficiency and high specific power three-phase Back to Back Power Converters has been proposed and theoretically investigated in this paper. Target applications are variable speed gen-sets, electric drives and independent power supplies. The solution proposed is based on a novel 5-Level E-Type topology. Advantages of the new solution, such as significant reduction of the input/output filter size/weight and switching losses have been theoretically investigated. A typical 20kVA independent gen-set power supply application has been analyzed as a case study. An extraordinary double conversion efficiency of 98.6% and specific power of 5kVA/kg have been achieved. The design results has been confirmed by set of Plexim/PLECS simulations. This work is a part of an ongoing PhD Dissertation with Center for Power Electronics and Drives (C-PED) Roma-TRE University, Rome, Italy.

Variable speed operation has been proposed in literature as a solution to efficiency and pollution problems for diesel generating units, as well to improve efficiency and power conversion in rotating systems for renewable energy sources. In general, different topologies of prime-movers, like internal combustion engines, wind turbines and hydro turbines, etc. can be used to move an electric generator at variable speed. In variable speed generating systems, the electric output frequency is disengaged from the mover speed through a power electronic converter. This paper deals with a newly-conceived variable speed generating unit to be used in on-board vehicle applications. The control structure is discussed and experimentally verified by means of a 40kW rated power converter prototype. It is shown that the proposed voltage control allows simplifying the overall control configuration and fast compensation of load unbalances. Further to that, a complete current limiting strategy is described and tested under different load conditions.

This paper deals with a newly conceived control topology based on the Repetitive action in 4-leg VSI for stand-alone Ground Power Unit (GPU) applications. In such mode of operation, a dedicated controller has to regulate the inverter output voltages, which are measured at the output of the power filter. The proposed Repetitive Control can provide the required harmonic compensation capabilities that are mandatory to comply with the Standards especially in the aircraft field, when balanced and unbalanced, linear and non-linear loads have to be fed at the fundamental frequency of 400Hz.

This paper presents the analytical design procedure to select the inductance and the capacitance values of both the input and output filters for the 5-Level three-phase Back to Back E-Type Converter (5L3Φ BTB E-Type Converter). The 5L3Φ BTB E-Type Converter is used to accomplish the double conversion AC-DC/DC-AC in applications which include variable speed industrial electric drives and the interfacing of renewable energy sources with the utility grids. The filter topology consists of a two-cell structure in interleaving coupling through magnetic devices (inter-cell transformer — ICT) and it is able to connected in parallel two legs for each phase of the 5L3Φ BTB E-Type Converter. The use of the two-cells interleaved topology offers the advantages of reduction of size, losses and cost of the input and output filter, reduction of current stress of the DC-bus capacitors and enables better utilization of the power semiconductors. The preliminary results obtained with a 400V, 20kW 5L3Φ BTB E-Type Converter are presented to validate the analysis and the analytical design procedure of the filters.

An analytical approach for accurate calculation of the conduction and switching power losses associated with the switching devices in the 5-Level 3-Phase Back to Back E-Type Converter (5L3ϕ BTB E-Type Converter) has been proposed in this paper. The 5L3ϕ BTB E-Type Converter is composed by two different multilevel topologies: the 5-Level E-Type Inverter and the 5-Level E-Type Rectifier. The power losses analytical equations can be used to investigate the converter's performance and efficiency as a function of the output power, the switching frequency and the modulation depth. Numerical results from the obtained analytical equations for calculation of conduction and switching losses of power devices have been compared with simulation results using Plexim/PLECS tool in Matlab/Simulink environment. The excellent match between analytic and simulation results validates the derived equations.

A master–slave synchronisation control problem is addressed for current-fed DC and permanent magnet synchronous motors with all uncertain parameters. A measurable exogenous rotor position reference signal, which belongs to the class of biased sinusoidal signals with uncertain bias, amplitude, angular frequency, phase, is to be tracked without assuming its a priori knowledge. An innovative modification of disturbance cancellation techniques allows to prove that an output feedback adaptive nonlinear control scheme, which simply generalises the classical internal-model-based input law, solves the aforementioned problem, with an overall stability proof concerning the entire closed-loop system. The practical effectiveness of the proposed approach is illustrated by experimental results.

Small distributed generation units are usually connected to the main electric grid through single-phase voltage source inverters. Grid operating conditions such as voltage and frequency are not constant and can fluctuate within the range values established by international standards. Furthermore, the requirements in terms of power factor correction, total harmonic distortion, and reliability are getting tighter day by day. As a result, the implementation of reliable and efficient control algorithms, which are able to adjust their control parameters in response to changeable grid operating conditions, is essential. This paper investigates the configuration topology and control algorithm of a single-phase inverter with the purpose of achieving high performance in terms of efficiency as well as total harmonic distortion of the output current. Accordingly, a Second Order Generalized Integrator with a suitable Phase Locked Loop (SOGI-PLL) is the basis of the proposed current and voltage regulation. Some practical issues related to the control algorithm are addressed, and a solution for the control architecture is proposed, based on resonant controllers that are continuously tuned on the basis of the actual grid frequency. Further, intentional islanding operation is investigated and a possible procedure for switching from grid-tied to islanding operation and vice-versa is proposed.

Multilevel power electronic topologies are being proposed in the recent technical literature for use in power generating units, especially when the reduction in the power filter overall dimensions and the lowering of current and voltage waveform ripple and total harmonic distortion are considered of primary importance. This is the case of high-speed gen-set units, where recent design techniques on high rotational speed permanent-magnet synchronous generators (PMSGs) have significantly reduced the inductance even for industrial voltage rated applications. This paper deals with a five-level unidirectional T-rectifier (5L T-RECT); the proposed topology is theoretically investigated, and simulation results and losses analysis are achieved with reference to an insulated-gate bipolar transistor (IGBT) phase-leg module which has been manufactured on purpose and tested.

This paper proposes a constant switching frequency Finite Control Set Model Predictive Control (FCS-MPC), formally Modulated FCS-MPC or M2PC, for a 4-leg inverter having an Active Split DC-bus on the fourth leg. The great advantage of MPC over linear control schemes is the very fast transient response it is capable to produce; it also can handle general constrained nonlinear systems with multiple inputs and outputs in a unified and clear manner. These features are highly valuable in power electronic converters used to supply the electrical utility loads in micro-grids. However, one of the main drawback of the MPC is its variable switching frequency, above all in system with accurately tuned output power filters (i.e. switching traps), which is the case when stable voltage waveforms with very low harmonic content are required. The proposed investigation relates with the application of a constant switching frequency variant of the MPC to a 4-leg inverter with a specifically tuned filter to assure high quality voltage supply even in case of non-linear and unbalanced loads.

This paper deals with a synchronous demodulation scheme to be used to obtain the speed and position from resolver position sensor. Proposed algorithm is intended to be implemented on a FPGA to provide the elaborated information for very low latency control loops. Moreover, resolver excitation circuit has been simplified working directly with a square wave signal. Resolver frequency behavior has been also taken into account due to the non-sinusoidal excitation.

1Simple adaptations of the latest design ideas in [2] suggest the existence of a new observer to be used for sensorless speed control of (nonsalient-pole surface) permanent magnets synchronous machines. The rotor speed measurement-assumed to be measured in [2] by a low-resolution transducer providing a single pulse per revolution — is here replaced by the output of a PLL (Phase Locked Loop) block that is based on a third-order Steady-State Linear Kalman Filter (SSLKF). Experimental results concerning the new observer are provided.

In this paper, a small signal model is proposed for the new unidirectional three-phase T-type rectifier topology known as five-level T-Rectifier (5L T-RECT). The proposed model is obtained starting from the large signal analytical representation of the 5L T-RECT configuration. The derived equations have been simplified using the synchronous reference frame transformation; to this purpose, the average values over the fundamental period T0 are considered for the input phase voltages. After that, the converter steady-state and dynamic models are derived by means of the local linearization around the desired operating point. The transfer functions related to the inputs and outputs of the system are, therefore, obtained and depicted. The achieved 5L T-RECT model has been first verified using the linear analysis tool in the matlab /Simulink environment starting from the detailed switching model. Theoretical results exhibit a very good accuracy between the small-signal, the large-signal, and the switching models. Then, experimental activity is depicted to further validate the proposed small-signal model.

The paper deals with a high efficiency boost rectifier for high rotational speed Gen-Set applications. It is tailored around a permanent magnet synchronous generator (PMSG) featuring an open end winding configuration. According to such a configuration the generator stator windings are connected on one side to a three level T-type unidirectional rectifier, and on the other side, to an auxiliary two-level inverter. The multilevel rectifier is operated at the fundamental frequency, while, the two-level inverter is driven by a standard sine PWM technique, in order to suitably shape the currents produced by the electric generator. The entire system is equivalent to a six-level multilevel converter. As the main stream power is handled by the multilevel rectifier operating at low switching frequency, a higher efficiency is achieved compared to a similar multilevel rectifier driven through a PWM technique, even considering extra losses due to the auxiliary inverter. The last can be supplied through an active source or a floating capacitor, and plays a key role in balancing the voltage across the DC Bus capacitors of the T-type rectifier, making unnecessary additional circuits. Suitable control solutions have been implemented considering either an active source, either a floating capacitor. Simulation results confirm the effectiveness of the proposed configuration.

High-speed electric drives play an important role in the field of power generating units on board vehicles and aircrafts. This paper deals with the solutions for developing the direct coupled electric drive to be used in combination with a radial turbo-expander for exhaust energy recovery in automotive applications. The descriptions of prototypal realization of both the axial-flux permanent-magnet (PM) generator and the three-level boost-rectifier converter, which results as the preferred topology for the controlled rectifier, are given. The high rotational speed of the direct-driven PM generator results in high electric fundamental frequency also, which is challenging for the electric drive control issues. Results of the electric drive prototype experimental activity are finally presented.

This study deals with a newly-conceived voltage control method for three-phase four-leg voltage source inverters (VSIs) 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. 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.

This paper deals with the gain scheduling feature for zero-phase-shift direct repetitive control (dRC) implemented in a FPGA system. Proposed control structure is intended to be used in ultra-low THD, fast transient response stand-alone generating applications. Moreover, implementation aspects of the dRC and gain scheduling algorithm are highlighted with reference to an industrial-grade μProcessor-FPGA control system and its graphical programming capabilities.

Nowadays, high-speed turbines for electric power generation represent a good idea for commercial, industrial and military applications, where small size and lightweight, low maintenance, reliability in a wide range of environments and good efficiency are required. However, the main equipment in such power generating units are the electrical generator systems, the AC-DC power electronic converter and the output inverter, when AC output load is unavoidable. Multi-level power electronic topologies have been under research and development for more than one decade and have been found successful in variable-speed drive applications. The new power converter topology, called Five-Level E Type Inverter (5L E-Type Inverter), is presented and analyzed in this paper with reference to the back-to-back configuration with a multi-level rectifier. The thermal models of the IGBTs and diodes have been created taking into account the parameters provided by the manufactures and employing multi-dimensional look-up tables in Plexim/PLECS environment. Simulation results are performed through Matlab/Simulink in order to evaluate efficiency and losses distribution for switches and diodes of the proposed 5L E-Type inverter configuration.

This paper deals with the usage of National Instruments LabVIEW and its dedicated control platforms in the field of Power Electronics and Drives (PED) control applications. Specific requests of the PED field are covered with respect to the Real-Time target, formally microprocessor, and the on-board FPGA. Paper is focused mainly on algorithm implementation and testing, as well as performance and resource utilization are discussed. Benefits of graphical programming are highlighted and compared with conventional text-based code editing methods, such as VHDL and Verilog.

This paper proposes a Predictive Control, formally Dead-Beat (DBC), for a four-leg inverter having an Active Split DC-bus on the fourth leg and LC filters on phase-to-neutral outputs. Such a configuration permits to reduce the voltage ripple on the neutral point connected to inverter grounding. As only few control techniques have been investigated for Active Split DC-bus, the paper proposes to investigate the performance of DBC, which has been widely used for other power electronics applications. The main advantage of DBC over the classical PI or Resonant controller is that no tuning is required for control loop, while obtaining very fast transient response as well it can handle general constrained nonlinear systems with multiple inputs and outputs in a unified and clear manner. These features are highly valuable in power electronic converters used to supply the electrical utility loads in micro-grids. However, one of the main drawback of the DBC is the limited capabilities on harmonics compensations required when supplying unbalanced and non-linear loads. The paper presents continuous-time and discrete-time models of DBC applied to a four-leg VSI with Active Split DC-bus, highlighting the performance through simulation results as well as experimental tests.

This paper deals with a dedicated load-adaptive phase compensation algorithm to be used in repetitive control (RC) based stand-alone four-leg voltage source inverter (VSI). The plant model is achieved; its inherent modifications according to the operating point are highlighted and used to properly adapt the RC structure. Modification of the RC parameters is described to obtain the desired phase compensation capabilities achieving a zero-phase-shift condition at each harmonic. This allows us to increase the gain of the repetitive controller at high-order harmonics, thus yielding a better VSI output voltage with strongly reduced total harmonic distortion and faster dynamic response. As a consequence, the VSI output voltages are almost independent from the loads to be fed, and the four-leg VSI with the proposed zero-phase-shift direct RC is an ideal candidate to supply sensitive loads in microgrid, in particular for stand-alone applications.

A small-signal model for the Input-Series Output-Parallel (ISOP) DC-DC converters is developed in this paper. The proposed model is obtained applying the State-Space Averaging technique. The ISOP DC-DC converter consists of multiple DC-DC modules connected in series at the input and in parallel at the output. In this paper, the ISOP DC-DC converters are used in combination with the 5-level unidirectional T-Rectifier for electric generating units in More Electric Aircraft systems. The small-signal model for the ISOP DC-DC converters has been verified through the direct comparison with the converter full digital-switching model, realized in the Matlab/Simulink environment. Simulation results exhibit a good agreement between small-signal model and switching model.

The position estimation problem is addressed for (nonsalient-pole surface) permanent magnets synchronous machines. Rotor speed and stator currents/voltages measurements are assumed to be available for feedback. Two novel adaptive observers are compared and experimental results concerning pump-fan and generating applications are provided.

The growing need for automation leads to the development of new electronic devices in greater and different fields of applications. One interest is new automation devices for high-voltage distribution substations. High-voltage circuit breakers (HVCBs) use a mechanical-based operation mechanism to open and close maneuvers. Conventional breaker drives are old and complicated to adapt to new electronics automated devices, such as remote monitoring supervision systems, measurements-acquisition systems, and protection systems. To obtain more flexibility and higher reliability, a new electronic operation mechanism, which can interface with modern substations and automation systems, is presented here and investigated. An evolution of the first electronic drive presented in the past years is described here through simulation and field test. Successful results gathered after IEC62271-100-type tests confirm the reliability and stability of this kind of new operating mechanism on full-scaled HVCBs and support its use in high-performance demand breakers, in terms of speed and energy request.

A master-slave synchronization control problem is addressed for current-fed permanent magnets synchronous machines with uncertain parameters and no speed sensor. An exogenous rotor position reference signal, which belongs to the class of biased sinusoidal signals with uncertain bias, amplitude, angular frequency, phase, is to be tracked without assuming its foreknowledge. An innovative output feedback adaptive nonlinear control scheme, which solves the aforementioned problem and simply generalizes the classical internal model-based input law, is presented. The effectiveness of the proposed approach is validated by experimental results.

Three-phase four-leg inverters are commonly employed to supply unbalanced loads avoiding the use of a transformer. A suitable output filter is necessary to improve the harmonic content of the output voltage and current waveforms. To this aim, different kind of filters, presenting both symmetrical and asymmetrical phase-to-phase and phase-to-neutral behavior, can be used. The paper discusses and analyzes the effects of different carrier-based modulation techniques, based on the independent control of the fourth leg from that of the other phases, with reference to the different filter topologies. The comparison, performed through extensive simulations and experimental tests, have demonstrated that in case of the asymmetrical filter utilization, such as the active split dc-bus (also known as split-link ), the conventional continuous and discontinuous space-vector modulations produce a significant harmonic content in the output voltages even at no-load condition. Moreover, the analysis is extended considering the interaction between the modulation strategy and load characteristics as linear, nonlinear, balanced and unbalanced loads. The problem is discussed in detail and a specific design procedure for the active split dc-bus is presented.

This paper deals with the fault tolerance analysis applied to the converter topology 5-level unidirectional T-Rectifier (5L T-RECT) to be used for electric generating applications. The proposed generating unit is intended for aerospace applications with high fundamental electric frequency, to this purpose the investigated power electronic converter configuration is able to supply power to the electric loads at different voltage levels. The depicted analysis has been performed to show the 5L T-RECT behavior in case of either switch or diode fault; identification and consequent action to be taken are shown in order to guarantee the converter continued operation.

This paper deals with the design solution adopted for a high-speed axial-flux permanent-magnet generator devoted to supplementing power in automotive 42 V electrical systems through a low-voltage multilevel neutral-point-clamped converter. The axial-flux permanent-magnet generator is suitably designed to be directly coupled with a radial turbo-expander which provides recovery of kinetic energy available from the exhaust gases of an internal-combustion engine. The multilevel converter is properly sized for systems having low voltage and high first-order harmonic frequency. The paper describes the proposed 4-kW power rating generating system and discusses various issues resulting from electromagnetic, thermal, and mechanical design of the high-speed axial-flux permanent-magnet generator. As well, investigations on modulation strategy, total harmonic distortion, and power losses are presented for the low-voltage neutral-point-clamped power electronic converter.

Zero-Voltage Transition (ZVT) DC-DC converters with active snubber can be used in photovoltaic applications requiring high efficiency and high-frequency isolation transformer. In order to improve the dynamic response of ZVT converters, two different current control strategies, namely Feed Forward and Dead-Beat, are proposed. The Feed Forward and Dead-Beat control, both based on the converter electrical model, produces better performance than a classical PI-type controller. After a detailed description of the mathematical models, the performance of the controllers are compared through specific MATLAB/Simulink simulation models. Finally, the obtained results are experimentally validated on a laboratory prototype.

This paper presents the analysis and the validation of the large-signals model of a new five-level T-type unidirectional three-phase rectifier topology known as 5L T-RECT. Proposed modeling approach is mainly based on the well-known state-space averaging technique. According to this technique, the averaging process is applied across one pulse width modulation sampling period ${\rm T}_S$ , thus resulting in the basic 5L T-RECT mathematical model. Consequently, the ac–dc steady-state operation is analyzed through the achieved model. The large-signals model of the 5L T-RECT has been verified by means of the direct comparison with the converter full digital-switching model, realized in the MATLAB/Simulink environment. Simulation results exhibit a good matching with the proposed average model.

Voltage-source inverters in microgrid stand-alone applications need the accurate control of the filter output voltages. Most of the time, supplied loads are not constant along daily based period; they change the total power consumption, the power factor, the current harmonic content of nonlinear equipment, and the power balancing among the phases. Consequently, the control dynamic behavior is affected, and the effectiveness of harmonic controllers is reduced. In this paper, the very sinusoidal shaping of inverter output voltage is achieved through a multiple resonant controller, which is adaptively tuned online according to the output power filter and load behavior. Resonant compensators are placed in the loop to achieve low total harmonic distortion of output voltage waveforms.

As required by international standards, the distributed energy generators, connected to the grid by an inverter, have to detect an islanding condition within a suitable time interval. In this paper, a phase-locked loop (PLL), based on a third-order prediction-correction filter, is proposed to implement an islanding detector with reduced detection time. Such a feature is obtained using the estimation of the grid angular frequency and acceleration provided by the PLL with a negligible time delay. The proposed approach is implemented on an industrial grade DSP and validated through the experimental comparison among different detection methods, such as rate of change of frequency (ROCOF) and Slip Mode frequency Shift (SMS). The combined use of ROCOF and SMS is also illustrated and discussed.

Grid-connected and stand-alone applications need inverters that accurately control the filter output voltages. Nowadays, resonant controllers (RCs) represent a good tradeoff between implementation issues and control performances. However, the unknown nature and size of supplied loads affect the dynamic control behavior and may reduce the effectiveness of the control system. A new structure of RC is introduced with the purpose of providing three degrees of freedom and allowing us to select independently the controller’s magnitude, width, and phase. In order to fully take advantage of the proposed RC form, the online tuning procedure based on the output filter analysis is also proposed. According to that, several resonant compensators can be placed in the loop to achieve a better output voltage waveform (i.e., lower total harmonic distortion).

This paper deals with the performance assessment of different power electronics configurations for the AC-DC converter based on the five-level unidirectional T-rectifier (5L T-RECT) to be used in gen-set applications. The comparison focuses on power electronics arrangements obtained with different switches and diodes technologies. At first, simulations are performed with Matlab/Simulink and Plexim/Plecs to highlight some relevant key points such as efficiency, losses distribution and finally converter sizing. A 5L T-RECT prototype has been built having a rate power equal to 17 kW to be used for validating the depicted results.

This paper deals with the performance assessment of different permanent magnet motor drives topologies for Starter/Generator systems in aircraft applications. The comparison focuses on power electronics topologies, evaluating, by means of simulations performed with Matlab/Simulink and Plexim Plecs, some relevant key points such as efficiency, losses and motor current harmonic distortion. For all the topologies, simulations have been carried out considering both 2-Levels and 3-Levels converter structures, and different machine arrangements. All the power electronics systems data are obtained from off-the-shelf power modules characteristics, both Silicon and Silicon Carbide technology based.

Three-phase four-leg inverters are commonly employed to supply unbalanced loads avoiding the use of a transformer. A suitable output filter is necessary to improve the harmonic content of the output voltage and current waveforms. To this aim, different kind of filters, presenting both symmetrical or asymmetrical phase-to-phase and phase-to-neutral behavior, can be used. The paper discusses and analyses the effects of different carrier-based modulation techniques, based on the independent control of the fourth-leg from that of the other phases, with reference to the different filter topologies. The comparison, performed through extensive MATLAB/Simscape simulations and experimental tests, have demonstrated that in case of an asymmetrical filter utilization, such as an Active Split DC-Bus (also known as Split-Link), the conventional continuous and discontinuous Space-Vector modulations produce a significant harmonic content in the output voltages. A detailed problem description and a specific design procedure is presented and validated by experimental tests, allowing a substantial improvement of the inverter performances.

Both the static and the dynamic end effects of the linear induction motor (LIM) cause an increase of the difficulty in controlling with good performance the main electro-mechanical characteristics of the machine, in particular the thrust and the linear speed. These effects are related to asymmetries in the inductor structure with respect to the rotating counterpart, in both the longitudinal and in the transversal direction. This paper propose a technique for the compensation of the LIM static end effects by a synchronous controller in conjunction with a neural adaptive filter, exploited to extract the inverse sequence current component from the inductor current signature. This permits to compensate the static-end effects and thus to cover the static asymmetries of the LIM with respect to the rotating induction motor (RIM).

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.

This paper deals with the EMI (Electromagnetic Interference) issue related to the power electronic converters of a hybrid vehicle. The effects of different configurations of the power supply system that feeds all the power conversion units are investigated in order to minimize the overall conducted EMI. In particular, two different power supply distribution networks (centralized and distributed) and related EMI filters architectures have been analyzed and compared in terms of conducted emissions and EMI filter sizes and efficiency.

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.

This paper deals with the design procedure of an LC-based output filter for three-phase inverters to be used in both off-grid and on-grid scenarios. The aim of this procedure is to provide guidelines and component selection criteria for reducing the inverter output switching ripple in order to limit the interaction with the control algorithm and to increase the filter stability. A suitable combination of resistive and reactive components is used to realize the complete filter structure. The proposed procedure is applied to the design of the output power filter for a 40-kVA three-phase inverter.

Voltage source inverters in micro-grid applications need the effective control of the filter output voltages. Harmonic compensation is a mandatory request to eliminate voltage distortion due to non-linear and unbalanced loads. The use of resonant controllers allows achieving high quality voltage regulation. The proposed paper investigates a closed form tuning strategy for controllers' parameters selection based on the symmetrical frequency behavior of the whole resonant controller structure. Symmetrically tuned controllers allow achieving the largest bandwidth around the resonance frequency in a multi-resonance controller structure.

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).

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.

Variable speed operation has been proposed in literature as a solution to efficiency and pollution problems for diesel generating units, as well to improve efficiency and power conversion in rotating systems for renewable energy sources. In general, different topologies of prime-movers, like internal combustion engines, wind turbines and hydro turbines, etc. can be used to move an electric generator at variable speed. In variable speed generating systems, the electric output frequency is disengaged from the mover speed through a power electronic converter. This paper deals with a newly-conceived integral-resonant single-loop output voltage control arrangement for a three-phase four-leg VSI, to be used in stand-alone microgrids, for a variable speed generating units using static conversion to provide the constant electric frequency required by the loads. The 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.

Single-phase voltage source inverters are commonly used for interfacing small distributed generation units to the grid. Requirement in terms of THD, reliability and power factor correction is getting tightening day by day, so it is necessary to implement efficient and reliable algorithms that are capable to adapt control parameters to the varying grid operating conditions, in order to assure low current distortion, as well high efficiency and reliability. This paper deals with the investigation of both configuration topology and control algorithm with the purpose of achieving high performance in terms of efficiency as well THD of the output current, despite the non ideal grid characteristics. The proposed inverter uses a second order generalized integrator based phase-locked loop, a single loop current control based on a grid frequency tuned proportional-resonant controller, and a damped output LC filter in cascade with a switching frequency tuned LC-series trap-filter.

""This paper deals with an adaptive control method to be used in the dc-link voltage controller of diesel-electric power supply units being arranged with both permanent magnet generator and three-phase boost-rectifier. The proposed control method is based on the suitable manipulation of the overall system transfer function to achieve an adaptive closed form expression for the parameters of the dc-link voltage controller. Such an approach allows overcoming the inherent non-linear behavior of the system, so that the overall system dynamic performance is not affected by the system load conditions. Moreover, a current feed-forward technique based on the estimation of the load current will be introduced to improve the control stiffness to load unbalances.""

This paper presents a complete design methodology for the sensorless vector control of permanent magnet synchronous machine (PMSM) motor drives in fan-type applications. The proposed strategy is built over a linear asymptotic state observer used to estimate the PMSM back-EMF, and a novel tracking controller based on a phase-locked loop (PLL) system, which by synchronizing the estimated and actual d-q frames estimates the rotor speed and position. The paper presents the complete derivation of all associated control-loops, namely state observer, tracking controller, d-q axes current regulator, speed controller, an anti-saturation control loop - which provides inherent operation in the flux-weakening region, and all corresponding anti-windup loops. Detailed design rules are provided for each of these loops, respectively verified through time-domain simulations, frequency-response analysis, and experimental results using a 300 Vdc 3.5 kW PMSM PWM motor-drive, validating both the design methodology and the excellent performance attained by the proposed control strategy

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.