Davide Da Ru

A test bench for hybrid propulsion train research and development

This paper presents a versatile laboratory test bench built up for carrying out researches and experimental tests about hybrid propulsion trains, without the availability of a real vehicle and an automotive test track. The test bench is realized by using a relatively low-power engine that can be combined with one or more electrical machines for emulating different hybrid architectures. In addition to the test bench structure, some examples of usage are also described in the paper.

An Integrated Starter-Alternator Based on a Sensorless Synchronous Reluctance Machine Drive

This paper deals with an integrated starteralternator based on a synchronous reluctance (REL) machine controlled by a sensorless drive. Advantages of the REL machine are high torque overload capability at low speed, extended flux-weakening capability, and inherent faulttolerance. The sensorless control of the synchronous REL machine is based on a combination of a high frequency injection technique (at low speed) and a flux model algorithm (at high speed). At first, the paper summarizes the design of the electric machine and gives some results of the finiteelement computations. Then the sensorless technique is deeply described. Drive performance is validated by experimental results by a hybrid laboratory test bench.

Secondary saliencies decoupling technique for self-sensing integrated multi-drives

The paper deals with the study and implementation of a secondary saliencies decoupling technique for self-sensing control algorithms used in multiphase motor drives and based on the injection of an additional high frequency excitation. The proposed approach can be applied to multiphase motors whose stator winding is composed of multiple three phase units suitably spatially shifted. The method exploits the spatial phase shift among the stator units to isolate undesired prominent saliency harmonics. Compared to the state of the art, this approach does not require multiple saliencies models or sophisticated filtering processes, but only the knowledge of the saliency harmonic order to be suppressed. Finite Element Analysis and Experimental results applied to a dual-three phase permanent magnet synchronous motor confirm the effectiveness of the method.

A robust current control based on proportional-integral observers for permanent magnet synchronous machines

This paper deals with a novel robust current control scheme for Permanent Magnet Synchronous Machine based on the conventional cascade structure. The main idea is to substitute the commonly used decoupling network, which requires the precise knowledge of the system parameters in any working condition, with a more flexible and robust scheme. In particular, the traditional configuration is improved by mean of two proportional-integral observers which allow the preservation of the drive performances under the effects of disturbance. The improved robustness is achieved maintaining the reliable basic scheme with a pure proportional controller in the forward path with advantages in terms of design and tuning. A genetic algorithm is used to optimize the controller and the observer parameters. This multi-objective optimization leads to a good stability and an overall improved performance of the drive above all the operative range. The choice of the optimal solution is based on a novel fitness function which takes into account both dynamical features and disturbance rejection capabilities of the system. The effectiveness of the proposed control scheme is verified by mean of numerical simulations and experiments as well.

Model Predictive Hysteresis Current Control for wide speed operation of a Synchronous Reluctance machine drive

This work presents a novel Model Predictive Hysteresis Current Control scheme for Synchronous Reluctance machine. The proposed algorithm predicts the plant behaviour considering the finite set of the power converter states and it chooses the most suitable voltage vector in order to reduce the current amplitude error and to minimize a cost function. The latter is designed to meet different goals depending on the operating conditions of the machine. In particular the Maximum Torque Per Ampere trajectory, the Flux Weakening region and the Maximum Torque Per Voltage operation are considered. In this way, a wide speed range operation is achieved and the current and voltage limits are inherently observed. The effectiveness of the control scheme is proved by mean of experiments.

An SPM Motor Drive Dressed as IPM Motor Drive for a Flexible Test Bench of Salient Rotor Propulsion Machines

The design of the powertrain of electric vehicles and hybrid electric vehicles could require the testing of different electrical machines in order to evaluate their performances and to find the most suitable solution for that specific propulsion system. The number of electrical machines that can be tested is limited by economical and practical issues. Moreover the numerical simulations cannot always represent a reliable mean to understand the real behaviour of the system. This paper presents a new mathematical model to emulate different virtual machines using only one real machine.

A new control strategy for high efficiency wide speed range synchronous reluctance motor drives

A synchronous reluctance motor drive exhibits an inherent unlimited speed range capability. In order to exploit this peculiar characteristic of the drive while assuring the lowest power losses, a proper control algorithm has to be used. In particular, while the working speed is increasing, the control must be able to command the reluctance motor under the maximum torque per ampere condition at first, into the flux weakening region, and then on the maximum torque per voltage trajectory. To this purpose, a novel voltage control loop is presented in this work. It is combined with a field oriented current control and profitably exploits a polar coordinate representation of the current reference to govern the drive working conditions. The result is a motor drive able to operate the reluctance machine in compliance with current and voltage rating constraints without speed limits. Additional merits of the proposed scheme are the ease of implementation and the simple design. The effectiveness of the proposed control algorithm is verified through simulations and experimental tests.

A moving horizon estimator for the speed and rotor position of a sensorless PMSM drive

In this paper, a systematic model-based approach for the state estimation of permanent magnet synchronous motors to build up sensorless drives is presented. A moving horizon estimation algorithm, an optimization-based scheme that yields excellent performance, is applied for the speed and position estimation. Under mild assumptions, an optimal problem of equality constrained quadratic programing type has been solved each iteration. The steady state and transient performance of the proposal are evaluated considering different horizon lengths. The influence of the latter is analyzed in terms of estimation error and computational burden. Besides, the behavior of the scheme is analyzed with different current control loops, i.e., with conventional proportional integral regulators and with model predictive control, highlighting its adaptability and good response in control schemes with completely different features. The performance is compared with that of an extended Kalman filter and the results prove the effectiveness of the proposed control scheme in terms of the estimation accuracy and robustness even at low speed operation. The algorithm has been efficiently implemented showing the real-time feasibility of the proposed approach up to 10-kHz sampling rate.

Model-free predictive current control for a SynRM drive based on an effective update of measured current responses

Predictive current control schemes strongly rely on the knowledge of the plant model. The accuracy of the current prediction could be affected by parameters variation or mismatch, non idealities and other model inadequacies. In Synchronous Reluctance Machine this effect could be particularly critical since its inherent intense iron saturation causes the variation of the indunctances in a wide range. For this reason, the nominal model could be unsuitable for current prediction and could lead to a severe deterioration of the drive performance. In this paper a novel Model-Free Predictive Current Control is presented. The current variations related to the feeding voltage vectors are recorded on-line and stored in a Lookup Table. The current prediction is later obtained by accessing the LUT in the position related to the considered voltage vector. The novelty of this work is the updating method for the Lookup Table. The proposed technique allows reconstructing all the current variations using only the responses related to the three most recent voltage vectors. The result is an improved Model-Free predictive current control in which the reliability of the prediction is guaranteed by the frequent LUT update while always observing the optimal control given by the cost function minimization.