An Overmodulation Algorithm With Neutral-Point Voltage Balancing for Three-Level Converters in High-Speed Aerospace Drives

Abstract

In this paper, a virtual space vector (VSV)-based overmodulation algorithm is presented for three-level neutralpoint-clamped (3L-NPC) converters in high-speed aerospace motor drives. With the proposed inscribed polygonal-boundary compression technique, the output voltage capability is enhanced under a lower crossover angle and compression coefficient. As a result, it brings an opportunity for the operation of the studied aircraft electric starter/generator (ESG) systems easily extending from the linear modulation range into the overmodulation region. Furthermore, an active capacitor voltage balancing control method is investigated to recover neutral-point (NP) potential imbalance in the case of high modulation index and low power factor operating conditions. To simplify the digital implementation of the algorithm, a fast calculation approach is adopted in this work. The modulation performance of the proposed strategy is verified by both simulation and experimental results with a 45 kW, 32 krpm ESG prototype system. Index Terms-High-speed motor drives, more-electric-aircraft (MEA), neutral-point voltage, overmodulation, three-level.

Analysis and Fault-Tolerant Control for Dual-Three-Phase PMSM Based on Virtual Healthy Model

“…Reliability is a core requirement in electrical drive systems, especially in more electric aircraft and electric vehicles [3][4][5][6]. And the fault tolerant control of PMSMs has been intensively studied to improve the reliability.…”

“…And the transform matrix is the same as that in three-phase PMSMs. The corresponding torque equation in DTP-PMSMs is shown in (6) in the synchronous reference frame.…”

An Advanced Modulation Technique Featuring Neutral Point Voltage Ripple Suppression of Three-Level Converters in High-Speed Drives

“…II, where +𝑖 𝑁𝑃 and −𝑖 𝑁𝑃 represents the neutral point current remaining the same or being inverted corresponding to the respective small vector. The variable 𝛥𝑉 𝐷𝐶 is defined in (15), where 𝑉 𝐶𝑢 and 𝑉 𝐶𝑙 represents voltages across the DC-link upper capacitor and the lower capacitor respectively.…”

“…In the generation mode, the engine shaft can be treated as large inertia, where mechanical power is extracted and transformed to electric power to supply various onboard electrical loads. For ESG applications, three-level Neutral Point Clamped (3L-NPC) is chosen over the classic two-level inverter [14] for Page 2 of 15 its advantages in efficiency and performance under a high fundamental frequency [15].…”

Speed/Torque Ripple Reduction of High-Speed Permanent Magnet Starters/Generators With Low Inductance for More Electric Aircraft Applications

“…The S/G system may simplify the power generation system by reducing the complexity of the mechanical subsystem, especially in aerospace and automotive applications, which would result in increased reliability and reduced overall weight [10]. Among its counterparts, high-speed permanent magnet starter/generators (PMS/Gs) have been a popular candidate due to their high power density and flexible bidirectional operation, which contributes to high instant power/torque output and better efficiency over a wide speed range [11][12][13][14].…”