Browsing by Keyword "efficiency improvement"
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Item Active Control of Variable DC-Link for Maximum Efficiency of Traction Motor Drives(2023-07-01) Pescetto, Paolo; Sierra-Gonzalez, Andres; Alvarez-Gonzalez, Fernando; Kapeller, Hansjorg; Trancho, Elena; Pellegrino, Gianmario; POWERTRAIN; Tecnalia Research & InnovationModern electric vehicles often interpose a DC/DC converter between traction battery and inverter, boosting the supply voltage of the drive. The power losses in the two converters and in the electric motor significantly vary with the DC-link voltage amplitude. In this work, a novel control algorithm is proposed to adapt online the DC-link voltage during vehicle operation, pursuing the maximum efficiency of the DC/DC converter and traction inverter without affecting the motor control dynamic. The key principle of the proposal, suitable for 3-phase and multi-three-phase drives, relies on the DC-link voltage minimization on varying the drive operating conditions. Among its advantages, the proposed variable DC-link control is independent of the motor parameters, the adopted torque/speed control strategy and the number of 3-phase sets of the drive. Although originally developed for electric vehicles, it can be adopted in a wide number of applications. Straightforward calibration roles are also provided. The proposed algorithm is deeply validated in simulation and experiments using a full-scale 135 kW 6-phase traction motor drive at TRL6.Item Discontinuous modulation of modular multilevel converters without the need for extra submodules(Institute of Electrical and Electronics Engineers Inc., 2015) Picas, R.; Ceballos, S.; Pou, J.; Zaragoza, J.; Konstantinou, G.; Agelidis, V. G.; Balcells, J.; POWER ELECTRONICS AND SYSTEM EQUIPMENTIn this paper, a new approach to the discontinuous modulation technique for the operation of the modular multilevel converter (MMC) is presented. Discontinuous modulation is based on adding a zero-sequence to the original modulation signals so that each MMC arm is clamped to the upper or lower terminals of the dc-link bus during some intervals. In combination with a circulating current control, the original discontinuous modulation can reduce the capacitor voltage ripple amplitudes and the switching power losses. However, additional submodules (SMs) are required to control the circulating current. This new approach presents a clamping algorithm that eliminates the requirement of additional SMs. As a result, the conduction losses are reduced while the capacitor voltage ripples are maintained low. Simulation and experimental results on a silicon-carbide-based MMC are reported and compared against the original discontinuous modulation and a conventional carrier-based pulse-width modulation.