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DAVIDE TEBALDI

Dottorando presso: Dipartimento di Ingegneria "Enzo Ferrari"


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Pubblicazioni

2021 - Modeling Control and Robustness Assessment of Multilevel Flying-Capacitor Converters [Articolo su rivista]
Zanasi, Roberto; Tebaldi, Davide
abstract

When performing AC/DC-DC/AC power conversions, multilevel converters provide several advantages as compared to classical two-level converters. This paper deals with the dynamic modeling, control, and robustness assessment of multilevel flying-capacitor converters. The dynamic model is derived using the Power-Oriented Graphs modeling technique, which provides the user with block schemes that are directly implementable in the Matlab/Simulink environment by employing standard Simulink libraries. The performed robustness assessment has led to the proposal of a divergence index, which allows for evaluating the voltage balancing capability of the converter using different voltage vector configurations for the extended operation of the converter, namely when the number of output voltage levels is increased for a given number of capacitors. A new variable-step control algorithm is then proposed. The variable-step control algorithm safely enables the converter extended operation, which prevents voltage balancing issues, even under particularly unfavorable conditions, such as a constant desired output voltage or a sudden load change. The simulation results showing the good performances of the proposed variable-step control as compared to a classical minimum distance approach are finally provided and commented in detail.


2021 - Power-Oriented Modeling of Epicyclic Gear Trains [Relazione in Atti di Convegno]
Zanasi, Roberto; Tebaldi, Davide
abstract

Model-based simulations are important in the automotive industry to study and evaluate the vehicle behavior. In this paper, the Power-Oriented Graphs (POG) technique is used as a tool for modeling epicyclic gear trains. A full elastic dynamic model of the system is first derived, which can then be reduced by neglecting the elastic contact points between the gears while still being able to recover the time behaviors of the spring tangential forces. The proposed modeling method is then applied to two epicyclic gear trains, and the design of a suitable control allowing to minimize the system dissipations is presented and applied to the second case study.


2020 - Estimation of Physical Parameters Using a New Discrete-time Derivative Algorithm [Relazione in Atti di Convegno]
Tebaldi, Davide; Morselli, Riccardo; Zanasi, Roberto
abstract

The paper presents a parameters estimation procedure for physical systems modeled using the POG (Power-Oriented Graphs) technique. The coefficients defining the constitutive relation for both static and dynamic physical elements within the system can be estimated, as well as the coefficients describing energy conversions taking place either within the same energetic domain or between two different energetic domains. The evolution of the state vector over time is supposed to be known, whereas its first derivative is supposed to be unknown and is obtained by using a new algorithm for computing the discrete-time derivative of a sampled signal, which is effective even in presence of disturbances affecting the signal samples. As long as the unknown parameters appear linearly within the system differential equations, the system is allowed to exhibit any nonlinear function of the state vector and its first derivative. The procedure is finally applied to two different case studies: a linear one and a nonlinear one.


2020 - Instantaneous Gearshift Model Based on Gear-dependent Angular Momentum [Relazione in Atti di Convegno]
Tebaldi, Davide; Zanasi, Roberto
abstract

The paper presents a new gearbox dynamic model for the effective simulation of simultaneous multi-clutches lock/unlock, by exploiting the Power-Oriented Graphs (POG) modeling technique. The generalized structure of the proposed model allows to simulate various gearbox configurations, which may foresee a change in terms of equivalent moment of inertia on the primary or secondary shaft, depending on the internal clutches configuration being function of the currently engaged gear. The peculiarity of the model lies in the instantaneous engagement of the new gear by skipping the slipping transient related to change of the internal clutches configuration, while preserving the natural loss of energy associated to it. The effectiveness of the presented gearbox model is finally tested and compared with classical gearbox modeling solutions with the aid of some simulation results.


2020 - Modeling Control and Simulation of a Series Hybrid Propulsion System [Relazione in Atti di Convegno]
Tebaldi, Davide; Zanasi, Roberto
abstract

This paper deals with the modeling control and simulation of a series hybrid propulsion system for driving a Wheel Loader by relying upon the Power-Oriented Graphs (POG) modeling technique. The considered propulsion system is composed of the following elements: an ICE (Internal Combustion Engine), two controlled PMSMs (Permanent Magnet Synchronous Motors), a supercapacitor as energy storage device and the transmission system of the vehicle itself from the gearbox all the way down to the vehicle wheels. A strategy for the control of the considered hybrid architecture is studied, with the objective of minimizing the ICE specific fuel consumption. Simulation results showing the operation of the presented strategy are finally reported and commented in detail.


2020 - Modeling and Simulation of a Multiphase Diode Bridge Rectifier [Relazione in Atti di Convegno]
Tebaldi, Davide; Zanasi, Roberto
abstract

In this paper, an analytical approach for modeling a multiphase diode bridge rectifier suitable for control purposes is presented. The model has been implemented in Matlab/Simulink by means of a function performing the AC/DC current conversion and takes into account the main non-idealities of semiconductor diodes, such as the turn-on voltage and the on/off resistances. The developed Matlab function makes the simulation of the multiphase diode bridge rectifier very straightforward and its effectiveness has been tested by comparing the simulation results with those obtained by using the rectifier model provided by the PLECS circuit simulator.


2020 - Modeling of Complex Planetary Gear Sets using Power-Oriented Graphs [Articolo su rivista]
Zanasi, Roberto; Tebaldi, Davide
abstract

In this paper, a systematic approach for the dynamic modeling of complex planetary gear sets is presented. The approach relies upon a set of rules for building the system matrices and vectors of the system full dynamic model for any planetary gear set. A congruent state-space transformation is applied to obtain a reduced-order rigid model of the system, which allows for faster simulations. The behavior of the tangential forces accounting for the gears interactions is proven to be obtained from the reduced-order model. Furthermore, the kinematic relations of the considered planetary gear set are automatically generated when developing the reduced-order rigid model. As an example, two systems of interest in the vehicle industry are then modeled with the proposed approach and simulated in Matlab/Simulink: a Ravigneaux planetary gear set and a double-stage planetary gear set.


2019 - Modeling and Control of a Power-Split Hybrid Propulsion System [Relazione in Atti di Convegno]
Tebaldi, Davide; Zanasi, Roberto
abstract

In this paper, the Power-Oriented Graphs (POG) technique is used to model a Hybrid Propulsion System for driving an agricultural tool. The main elements present in the system are: an ICE (Internal Combustion Engine), two PMSMs (Permanent Magnet Synchronous Electric Motors) equipped with two inverters in order to be properly driven, a planetary gear, an energy storage device and an agricultural tool. Based on the system dynamic model, a dedicated control strategy has been developed allowing to efficiently control the system by reducing the ICE specific consumption as much as possible. Simulation results showing the operation of the control strategy are finally reported and commented in detail.


2019 - Planetary Gear Modeling Using the Power-Oriented Graphs Technique [Relazione in Atti di Convegno]
Zanasi, Roberto; Tebaldi, Davide
abstract

In this paper, the Power-Oriented Graphs (POG) technique is used to model Planetary Gear transmission systems. The full elastic dynamic model of the system is obtained using a fast and direct method which can be easily applied to any type of planetary gear. The rigid and reduced dynamic model of the system when the stiffness coefficients go to infinity is then obtained using a POG congruent state space transformation allowing the user to select which angular speeds are to be maintained in the reduced model. Another interesting aspect of the presented method is that the obtained reduced model is still able to provide the time behaviors of the tangential forces present between each couple of gears of the considered planetary gear system. The presented fast and direct method is then applied to two practical case studies, and simulative results in Matlab/Simulink showing the effectiveness of the method are finally reported and commented.


2019 - Power Flow Efficiency of Linear and Nonlinear Physical Systems [Relazione in Atti di Convegno]
Zanasi, Roberto; Tebaldi, Davide
abstract

In this paper, an analytical procedure to derive the efficiency of linear and nonlinear physical systems is presented. This procedure allows to compute the efficiency map both on the plane of the input power variables and on the plane of the output power variables. Additionally, the paper highlights the parameters to be adjusted in order to enlarge the high-efficiency region of the system. The presented procedure can also be used in conjunction with a least square algorithm in order to estimate the unknown parameters of the considered physical system. The effectiveness of the procedure has been tested in Matlab/Simulink to estimate the parameters of an actual PMSM electric motor. The obtained results show a very good matching between the actual and the estimated efficiency maps.


2019 - Study of the Bidirectional Efficiency of Linear and Nonlinear Physical Systems [Relazione in Atti di Convegno]
Zanasi, Roberto; Tebaldi, Davide
abstract

In this paper, a study of the bidirectional efficiency of linear and nonlinear physical systems is performed. The methodology to compute the bidirectional efficiency map of the system is described, highlighting which is the power flow orientation giving the maximum system efficiency. The designer can therefore easily evaluate whether a physical system, such as for instance an electric machine, is more suitable for being used in forward motor mode rather than in reverse generator mode or viceversa. Three different types of physical systems are modeled and simulated in Matlab/Simulink, and the different characteristics they exhibit in terms of efficiency are highlighted. Finally, the properties that the efficiency maps exhibit if the linear system is affected by symmetric or nonsymmetric nonlinearities are studied and commented in detail.