Omar Bottesi

Computation and measurement of high frequency parameters in a synchronous machine

This paper presents the computation and the measurement of the high frequency parameters in an inset permanent magnet synchronous machine. Different operating conditions are considered: both at no-load and under load. The d-q model at high frequency of the synchronous machine is briefly recalled and then the simulation strategy is introduced. Then the experimental setup is described and the measurement procedure detailed. Finally the simulated parameters are compared with experimental results, considering different stator currents and rotor angles.

Energy efficiency improvement adopting synchronous motors

Purpose – The purpose of this paper is to compare different types of electric motor drives for high-efficiency applications: an induction motor (IM) drive, a synchronous reluctance motor drive and a permanent magnet-assisted synchronous reluctance motor drive. An innovative field-oriented analysis technique is applied to estimate the performance of the IM drive. This method of analysis is particularly advantageous in comparing the IM performance to those of synchronous machines. Design/methodology/approach – The comparison among the capabilities of the three electric drives is carried out combining both analytical and finite element methods. Findings – From the analysis, it results that the REL motor exhibits higher torque density than IM, but lower losses since there are no Joule losses in the rotor. On the contrary, the REL motor exhibits a very power factor, which corresponds to a high-volt-ampere ratings of the inverter that supplies the motor itself. Originality/value – A new analysis technique is ad...

Finite Element Small-Signal Simulation of Electromagnetic Devices Considering Eddy Currents in the Laminations

This paper presents the validation of a small-signal finite-element simulation strategy comparing different simulation approaches. At first, a full 3-D non-linear model in the time domain is presented. Then, the small-signal strategy has been applied to the 3-D model achieving a considerable reduction of computational time. In both 3-D models, the eddy currents in the laminations are fully modeled. Then, in order to avoid 3-D model, a 2-D model has been considered. In this case, eddy currents are included adopting a homogenization technique. In the 2-D case, both non-linear time domain simulations and small-signal strategy have been implemented. The results of the four considered simulation strategies are in very good agreement, proving that the small-signal simulation strategy can be profitably used in order to reduce significantly the computational cost. As an example, this paper considers a two-port mutual inductor as a test model.

A computational technique for iron losses in electrical machines

This paper aims to compare different methods for the computation of the iron losses. First of all, a brief recall on iron losses models is considered. In particular, Bertottis formula, a homogenization technique and a vectorized Jiles-Atherton model are implemented. Afterwards, the adopted methods are validated considering an iron ring and an inset PM synchronous machine. A comparison between experimental measurements on the iron ring and the adopted methods is presented. The inset PM synchronous machine is simulated in different operating conditions: both at standstill and no load. Good agreement has been found between the results.

Design of small-size generator for variable speed micro-hydroelectric power plants

This paper considers the design of a high efficiency small-size generator for micro-hydroelectric energy production. Different generator designs are compared in order to identify the best solution to be adopted in such installations. Due to the small power rating, the same generator is considered in different installations, with different net heads and water flow. This allows to improve the cost-effectiveness of the system. This is achieved operating the generator at different frequencies in various conditions, being the grid connection achieved by means of an inverter. Therefore, the performance of the designed generators are evaluated considering also operations at different speed.

Variable speed operation of micro-hydroelectric power generators

During the last years, energy efficiency has become one more and more important problem. Therefore, it is important to exploit the energy sources at best. The potential hydroelectric energy is almost totally exploited in Italy, but it still exists the possibility to manufacture new micro-hydroelectric plants. Nevertheless, design costs are very burdensome because it needs to consider a specific design for each plant. In this paper, a only system has been designed in order to adapt it at different operating conditions and, therefore, to reduce the pay-back period. Particular attention is paid to the efficiency of the generator.

Comparison of small-size generator for high-efficiency hydroelectric energy production

Micro-hydroelectric power plants exhibit low efficiency due to the small size. For this reason, the selection of a high-efficiency electrical machine is particularly important in order to improve the performance of the generation system and to respect the energy policies. In this paper, the performance of different types of machine are computed and compared. In particular an Induction Machine (IM), a Synchronous Permanent Magnet (SPM) machine, a Synchronous Reluctance Machine (SynRM) and a Permanent Magnet-assisted Synchronous Reluctance Machine (PMaSynRM) are considered. The performance of the considered machines are predicted by means of Field-Oriented (FO) analysis technique applied to FE models of the four machines. The comparison between the machines refers to the same stator geometry. The SPM machine exhibits the best performance.

Investigation on the frequency effects on iron losses in laminations

This paper aims to investigate through simulations and experimental results the effects of frequency on the iron losses in laminations adopted for electrical machines. To this aim, a comparison between an iron loss separation model and an advanced model (based on a nonlinear homogenization technique and the Jiles-Atherton model) is presented. Then, a new measurement method is introduced: an industrial inverter is adopted to impose a square waveform as supply voltage. The considered specimen is achieved from a real stator lamination where the windings are wound around the back iron. From the measurement, the constants of the iron loss separation model along with the Jiles-Atherton parameters are calculated and used in the FE model. Finally, the measurements and simulation results are compared and commented. Good agreement between measurements and simulation results have been found.

Self-commissioning of sensorless drive for synchronous machine: Finite element analysis computation and measurement of flux maps

This paper aims at comparing different methods for the identification of flux characteristics and differential parameters of synchronous machine adopted in sensorless drives. In particular, two computational methods and one experimental method are considered: the first method is based on a Small-Signal FE simulation strategy, while the second method is based on Time-Domain FE simulations. Both strategies allow to include high-frequency and parasitic effects. The obtained results are compared with experimental measurements on an Interior Permanent Magnet Synchronous Machine.

Self-adaptive high-frequency injection based sensorless control for IPMSM and SynRM

An auto-tuning and self-adaptation procedure for high-frequency injection (HFI) based position and speed estimation algorithms in IPMSM and SynRM drives is proposed in this paper. Analytical developments show that the dynamics of the high-frequency tracking loop varies with differential inductances, which in turn depend on the machine operating point due to saturation. On-line estimation and adaptation of the small-signal gain of the loop is proposed here, allowing accurate auto-tuning of the sensorless control scheme, even without any a priori knowledge of the machine parameters. Interesting byproducts of this proposal are the possibility for on-line adaptation of the current controllers and of the injected voltage magnitude, leading to important advantages from the performance, loss and acoustic point-of-view. The theoretical basis of the method will be first introduced and the main concept demonstrated by means of simulations. Implementation has been carried out using the hardware of a standard industrial drive and two 2.2 kW prototype IPMSMs. Experimental test results demonstrate the feasibility and effectiveness of the proposal.