Characterization of the parameters of interior permanent magnet synchronous motors for a loss model algorithm

The paper provides the results of a detailed experimental study on the variations of the characteristics of an interior permanent magnet synchronous motor, when load, speed and/or magnetization conditions vary. In particular, the characterization is carried out by assessing, for several working conditions, the motor parameters that influence its efficiency. From the knowledge of the variability of these parameters, it is possible to develop a dynamic model of the motor, which accurately describes its behaviour and allows estimating the power losses for whatever speed and load. In order to validate the model, the values of the power losses obtained by using the model are compared with the values measured with experimental tests. The study shows that it is possible to maximize the motor efficiency just acting on the direct axis current component and, therefore, it can be considered a first step towards the definition of a loss model algorithm for a control drive system able to minimize in real-time the power losses of the motor

A Novel Multi-Objective Finite Control Set Model Predictive Control for IPMSM drive fed by a Five-Level Cascaded H-Bridge Inverter

In this work, a novel multi-objective voltage-vector-based finite control set model predictive control for a permanent magnet synchronous machine drive fed by a three-phase five-level cascaded H-bridge multilevel inverter is proposed. This algorithm aims to overcome the main issues relative to model predictive control implementation detected in the scientific literature for electric drives fed by cascaded H-bridge multilevel inverters. In detail, the goals are the minimization of computational cost by reducing the number of required predictions, the minimization of the switching devices state transitions, i.e. the switching losses minimization, and the common mode voltage reduction. These goals are fulfilled through an offline optimization process, thus, no additional terms and weighting factors to be tuned are required for the cost function. Experimental validations are presented to prove the effectiveness of the proposed approach. In detail, an accurate electric drive performance comparison, both in steady state and dynamic working conditions, is carried out when the proposed voltage-vector-based model predictive control and the cell-by-cell-based model predictive control are adopted. As comparison tools, current and voltage total harmonic distortion, apparent switching frequency, common mode voltage amplitude, and torque ripple are adopted

Recursive Selective Harmonic Elimination for Multilevel Inverters: Mathematical Formulation and Experimental Validation

A recursive method that eliminates +1 harmonics and their respective multiples from the output voltage of a cascaded H-bridge multilevel inverters with = 2 dc sources ( = 1, 2, 3,...) is proposed. It solves 2×2 linear systems with not singular matrices and always gives an exact solution with very low computational effort. Simulated results in three-phase five, nine, seventeen and thirty three level CHB inverters, and experimental results in five-level inverter demonstrate the validity of the method

Comparison between Voltage Oriented Control and Synchronous Power Control for Grid-Connected Inverter Applications

With the rising of renewable power generation, there are new challenges to be addressed in order to maintain the electrical system operation stability. So, in literature, new grid-connected inverter control techniques have been studied. This paper focuses on a comparison between a grid-following control technique, called Voltage Oriented Control and a grid-forming control technique, called Synchronous Power Control, to underline the advantages offered by the latter. Through a simulation analysis in Matlab/Simulink environment, the benefits and drawbacks of these control approaches have been analyzed and discussed

Optimized Finite Control Set Model Predictive Control for a Three-Phase Five-Level Cascaded H-Bridge Multilevel Inverter fed Interior Permanent Magnet Synchronous Machine With On-Line Candidate Switching State Selection

Model predictive control is a novel control strategy that is attracting the scientific community due to the several advantages it offers, such as the ability to consider system nonlinearities, the possibility to synthesize a control for a MIMO system instead of multiple SISO, and so on. Control feasibility, due to the very high computational cost required to solve the optimal control problem, is a challenge. By considering electric drives fed by multilevel inverters, the control design is more challenging due to the increased number of available output voltage vectors. In this work, a simple algorithm for the voltage candidate reduction is presented: it allows for reducing the control computational cost, minimizing the switching losses, and minimizing dv/dt on phase voltage waveforms

Impact Evaluation of Innovative Selective Harmonic Mitigation Algorithm for Cascaded H-Bridge Inverter on IPMSM Drive Application

This paper presents a detailed analysis of the use of a novel Harmonic Mitigation algorithm for Cascaded H-Bridge Multilevel Inverter in electrical drives for the transportation field. For this purpose, an enhanced mathematical model of Interior Permanent Magnet Synchronous Motor (IPMSM), that takes into account simultaneously saturation, cross-coupling, spatial harmonics, and iron loss effects, has been used. In detail, this model allows estimating accurately the efficiency and the torque ripple of the IPMSM, crucial parameters for transportation applications. Moreover, two traditional pulse width modulation strategies, Sinusoidal Phase-Shifted and Switching Frequency Optimal Phase-Shifted have been considered for comparison purposes with an optimized harmonic mitigation algorithm. Thus, this work provides a deep analysis of IPMSM drive performance fed by CHBMI, paying attention to various aspects such as the IPMSM efficiency, torque ripple, current, and voltage total harmonic distortion (THD). Finally, experimental investigations have been carried out to validate the analysis conducted

Comparison of three control drive systems for interior permanent magnet synchronous motors

In a previous paper, we proposed a control strategy for interior permanent synchronous motors, which takes into account also the reduction of the motor power losses. The novelty of the suggested approach is that it takes into consideration the variations of all the motor parameters that have an influence on its efficiency. In order to verifyon the field the effectiveness of this new method, we implemented the proposed loss model algorithm in a control drive system and compared its performances, in terms of energy losses with respect to other conventional techniques

MC-PWM Harmonic Losses Determination in IPMSM drive fed by Cascaded H-Bridges Multilevel Inverter

The use of Multilevel Inverters (MIs) in PMSM drives is a possible solution for motor harmonic power losses reduction. In this regard, their experimental determination is a challenging task. This paper addresses an experimental analysis of harmonic losses introduced in an IPMSM drive fed by a Cascaded H-Bridges Multilevel Inverter (CHBMI) controlled with different MultiCarrier PWM strategies (MC-PWM). For this purpose, a frequency domain power analysis approach has been adopted to separate the active power value generated at the fundamental harmonic frequency and the power losses at the higher harmonics. In this analysis, several working conditions, defined in the frequency-torque plane, have been considered and the detected IPMSM total power losses, fundamental power losses and harmonic power losses have been discussed

An Experimental Comparison between an Ironless and a Traditional Permanent Magnet Linear Generator for Wave Energy Conversion

Permanent Magnet Linear Generators (PMLGs) are currently being studied for sea wave energy harvesting. Typically, a PMLG consists of an iron-made armature and a moving translator. The permanent magnets adoption produces parasitic effects, such as cogging force, and the machine weight increment. A solution could be the adoption of an ironless configuration, accepting a power density reduction. This paper investigates the use of ironless PMLGs in sea wave energy conversion systems by an experimental comparative analysis between an iron PMLG prototype and an ironless PMLG prototype, which share the same geometry. The main electrical and mechanical parameters (resistance, mass, and magnetic fields) were preliminarily measured. Subsequently, open-circuit and load tests were carried out to compare the induced voltages, the energy transferred to a resistive load, efficiency and the load average power. The reported comparison shows that iron PMLG performances are significantly superior to the ironless ones during the open-circuit tests, as expected. However, the analysis carried out through the load tests shows that the cogging force significantly limits the energy production, obtaining similar values in both machines. Therefore, the experimental tests justify the use of ironless machines in sea wave energy harvesting, where the maximization of energy production is a relevant target

A simple DC-Link Voltage Balancing Strategy for NPC Three-level Inverters

Three-level neutral point clamped PWM inverters overcome some limitations of two-level inverters in medium voltage applications, leading to lower device ratings and greater efficiency. However, they are burdened by an intrinsic drawback of the neutral point clamped structure, which causes, under some operating conditions, a voltage imbalance of the DC link capacitors. In this paper, such an issue is faced on a system driven by a dual-carrier PWM strategy through a simple hysteretic control. The proposed technique features a very low computational burden and does not need additional power circuits or sensors. It is first presented theoretically, then its performance is evaluated through simulations