A Low‐Speed, High‐Torque Motor Drive Using a Modular Multilevel Cascade Converter Based on Triple‐Star Bridge Cells (MMCC‐TSBC)

Abstract

This paper provides an experiment-based discussion on a modular multilevel cascade converter based on triplestar bridge cells (MMCC-TSBC) for a low-speed hightorque motor drive. The TSBC is a direct ac-to-ac power converter capable of achieving bidirectional power flow as well as drawing and feeding three-phase sinusoidal input (supply-side) and output (motor-side) currents with any power factor at both sides. This paper discusses active dccapacitor-voltage control applied to the low-speed, hightorque motor drive. A specially designed downscaled system combining a 320-V, 38-Hz, 6-pole, 15-kW induction motor with a 400-V, 15-kW TSBC is constructed and tested to confirm the validity of the motor drive. Experimental waveforms obtained from the downscaled system confirm stable operation with the rated load torque across a range from a standstill to the rated speed, including satisfactory start-up performance. C⃝ 2016 Wiley Periodicals, Inc. Electr Eng Jpn, 198(4): 73-82, 2017; Published online in Wiley Online Library (wileyonlinelibrary.com).

Behavioral Device-Level Modeling of Modular Multilevel Converters in Real Time for Variable-Speed Drive Applications

“…The modular multilevel converter (MMC) has received tremendous attention in recent years with wide industrial applications in medium-and high-power occasions, such as static synchronous compensator [1]- [3], renewable energy grid connection [4]- [6], medium-power drives [7], [8], and highvoltage direct current (HVdc) transmission projects [9], [10], where this voltage source converter (VSC) has been gaining momentum and is expected to overtake traditional thyristorbased line-commutated converters as the main vehicle for electrical energy conversion due to its advantages such as resilience to commutation failure and capacity of regulating reactive power. Meanwhile, it also has merits over traditional two-level or other multilevel converters such as high-power quality quasi-sinusoidal output waveforms, obviating the need for bulky filtering equipment and scalability, which allows the number of submodules to be flexibly changed to adjust to different voltage stresses or to produce the demanded voltage levels.…”