This paper deals with real-time estimation of the junction temperature of SiC power mosfets. The junction temperature of a device with four-switch module is estimated in real-time by measuring its current and on-state voltage V _ON at each switching period and entering the temperature in the lookup table of the device. The temperature model is preliminarily obtained in a dedicated commissioning session, where V _ON is measured at different temperature and current conditions. The results show the feasibility of online temperature monitoring and even the active limitation of the junction temperature of the tested SiC power mosfet modules accurately and with an instantaneous dynamic response. Different modules with die from different manufacturers were tested in an H-bridge demonstrator power converter, emulating the operating conditions of real converters such as voltage source dc/ac or dc/dc conversion structures. The commissioning procedure is meant to be performed directly on the final application for each converter. The measurements obtained using the proposed temperature estimation technique are validated using a thermal camera and compared to the direct measurement of the die temperature with a thermistor, showing high accuracy and high feasibility.

The drive inverter is a crucial component of an electric vehicle (EV) powertrain, being responsible for the DC/AC power conversion between the battery and the electric motor. The increasing demand for lower weight and higher conversion efficiency is opening new challenges, encouraging the adoption of new technologies (e.g., wide bandgap semiconductor devices). In particular, the DC-link capacitor typically represents the bulkiest inverter component, posing a strict limitation to the achievable converter power density and thus being subject to great pressure for improvement. In this context, novel ceramic capacitor technologies (e.g., PLZT) promise superior performance with respect to well established film-based solutions, featuring both higher specific capacitance and higher RMS current capability. Therefore, this paper focuses on the analysis, sizing, design and experimental assessment of a PLZT-based ceramic DC-link capacitor for next-generation EV drive inverters, including a comparative assessment with a state-of-the-art film-based solution. In particular, in view of the non-linear behavior of the PLZT capacitance value with respect to the DC-bias voltage and the amplitude of the excitation, a novel correlation between the effective large-signal capacitance and the peak-to-peak voltage ripple is derived experimentally, providing useful information for the DC-link capacitor sizing (i.e., not available from the capacitor manufacturer). For verification purposes, a full-scale DC-link capacitor prototype for a SiC MOSFET 800 V, 550 kVA, 20 kHz drive inverter is realized, demonstrating superior power density (i.e., $\approx$ two thirds smaller and $\approx$ one third lighter than a corresponding film-based solution). Finally, the inverter prototype is also exploited to validate experimentally the proposed DC-link peak-to-peak voltage ripple estimation procedure, based on the newly obtained large-signal capacitance characterization.

The rapid spread of electric vehicles is pushing for more and more compact and reliable e-axle architectures. In this scenario, the integration of the on-board battery charger with the traction drive can be a feasible way to reduce the embedded volume and number of components. Anyway, integrated chargers often present safety issues due to the absence of an isolation stage. In this work, a solution is proposed for integrating the on-board battery charger with the traction drive of road electric vehicles equipped with a 6-phase traction motor drive. The proposed charger is deeply integrated within the e-drive powertrain, to reduce the cost and volume of the e-axle with respect to non-integrated solutions, but still providing galvanic insulation, differently from all fully integrated charger in the literature. Dedicated control strategies are developed and tested for regulating the AC grid current at unitary power factor and low THD, and to avoid torque production or rotor movement during charging independently from the rotor position. Extensive simulation results show the feasibility of the proposed solution, together with a proof-of-concept validation on a commercial traction motor.

The compensation of converters’ nonlinear voltage error is crucial in encoder-less control of ac motor drives. In this paper, a new self-commissioning and compensation method is proposed for matrix converters (MC). Similar to what done in the past for voltage source inverters, the MC voltage error is identified before the drive start and stored in a look-up table (LUT), later used for error compensation and accurate voltage estimate. Different from what observed in the past, the effect of parasitic capacitors on nonlinear voltage error of MCs in four-step current based commutation is observed and studied. Eventually, this method is applied to the sensorless control of a synchronous reluctance (SyR) motor drive, using the direct flux vector control (DFVC) concept. Experimental results are presented to validate the effectiveness of proposed self-commissioning in improving the performance of sensorless control at standstill and low speed.

The recent years have seen exponential growth in electric generation from renewable energy sources (RESs), such as wind and sun. This scenario represents an opportunity to decarbonize part of the energy sector and phase out fossil fuels. However, particular care must be taken to ensure the correct operation of the electric grid. With a large penetration of power electronics-based generation, special care must be taken in the case of grid faults, due to limited short-circuit current capabilities of static converters, supporting the grid in the case of faults. For this reason, static converters have to be transiently overloaded to inject fault currents larger than their nominal limit, mimicking the behavior of synchronous generators (SGs). Therefore, this article proposes the combined solution of a transiently overloadable virtual synchronous machine (VSM) converter equipped with real-time semiconductor junction temperature limitation. The VSM provides the necessary short-circuit current references and the inverter can be overloaded with an active thermal control strategy, avoiding the oversizing of the power semiconductors, by properly exploiting their thermal limits. This represents a possible path for further power electronics integration into the grid.