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.

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 highefficiency 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.

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.

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.

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