Powertrain modularity

This paper derives and discusses the superiority of a simple dc-link capacitor voltage control configuration for multilevel neutral-point-clamped converters with any number of levels. The control involves n − 2 control loops regulating the difference between the voltage of neighbor capacitors. These control loops are inherently decoupled, i.e., they are independent and the control action of one loop does not affect the others. This method is proven to be equivalent to previously published approaches, with the added advantages of increased simplicity and scalability to a higher number of levels, all while imposing a lower computational burden. The good performance of such control is confirmed through simulations and experiments.

Multilevelπ π-type and ANPC converters without flying capacitors and clamping diodes are emerging candidates for industrial applications due to their simple structure, less number of devices, and better harmonic performance. However, the voltage balancing difficulty is the key issue of these topologies similar to diode-clamped topology under conventional PWM methods. The unbalance of capacitors voltages may affect the system integrity and stability, and may degrade harmonic performance. To sort out this issue, a simplified virtual vector PWM method to balance the dc-link capacitors voltage of four-level three-phase π -type and ANPC converters is presented in this paper. Simulation results show how easily and efficiently the proposed method can control the voltage of the capacitors for different modulation index values under balanced and unbalanced loads.

Gallium nitride (GaN) and silicon carbide (SiC) semiconductors can improve the power converters used in electric vehicles. These devices offer significant advantages due to their ability to operate at high switching frequencies while maintaining high efficiency. This paper presents a comprehensive comparison of modulation techniques for hybrid T-type converters that use SiC and GaN semiconductors. The analysis compares modified sinusoidal pulse-width modulation (M-SPWM), double-signal pulse-width modulation (DSPWM), and carrier-based pulse-width modulation (CB-PWM) techniques in terms of efficiency and DC bus balancing capabilities. The study examines the normalized voltage ripple and losses on the DC bus utilizing MATLAB/Simulink and PLECS. The simulation results indicate that DSPWM and CB-PWM hold promise as viable alternatives to the traditional M-SPWM technique for electric mobility applications, particularly when the power converter operates at high switching frequencies.

This deliverable reports on the switching tests validating the driver design of the highpower 150 kW hybrid T-Type converter for the RHODaS project. The study addresses the challenges of integrating Wide Band Gap (WBG) semiconductors, specifically Gallium Nitride (GaN) and Silicon Carbide (SiC), in high-voltage configurations to enhance efficiency. While the initial prototype faced reliability issues, a redesign utilising GaN Systems devices (GS66516B) and negative turn-off voltage successfully mitigated parasitic turn-on risks. Experimental analysis confirmed robust operation up to 1000 V. However, high commutation loop inductance (≈100 nH) necessitated limiting switching rise times to 70100 ns via adjusted gate parameters (Rgate=22 Ω, Cgate=4.7 nF). This adjustment prioritised reliability over minimal switching losses. Regarding control, whilst advanced CBPWM and SPWM strategies were implemented in the System on Chip (SoC), some constraints prevented their full experimental validation. Thus, standard Space Vector Modulation (SVPWM) will be employed for final testing.  In conclusion, the project delivered a robust GaN stage capable of 1000 V operation, though the validation of custom modulation techniques remains pending.