Zhou, Shaoze, Li, Binbin, Xu, Dianguo and Li, Gen ![]() ![]() |
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Abstract
The modular multilevel converter (MMC) is a promising topology for medium-voltage drive applications due to its high-quality output waveforms, low device switching frequency and voltage rating. However, the large cell capacitor voltage ripple is a severe challenge faced by MMC at low motor speeds. Recently, a hybrid MMC (HMMC) topology is proven to be a competitive solution because of its lower cell capacitor voltage ripple and no common-mode voltage (CMV) problem compared with other methods. However, the dc-link switch with IGBT limits HMMC to be applied for high-voltage applications. This paper uses the thyristor instead of IGBT as the dc-link switch. To ensure the thyristor can be softly turned on and safely turned off, a new control scheme is proposed. When using this proposed scheme, HMMC can also tolerate the failure of thyristor's turning-off without shutting down the system, improving the reliability effectively. The cell capacitor voltage ripple analysis is presented considering the effects of the thyristor switching process. In addition, a decoupled energy balancing control is utilized to suppress the fluctuation of dc current. Experimental results obtained from a 380 V/7.5 kW downscaled prototype validate the effectiveness of starting up a motor from the standby mode to rated speed with full-torque.
Item Type: | Article |
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Date Type: | Publication |
Status: | Published |
Schools: | Engineering |
Publisher: | IEEE |
ISSN: | 2096-0042 |
Date of First Compliant Deposit: | 10 June 2021 |
Date of Acceptance: | 10 June 2021 |
Last Modified: | 07 Nov 2023 01:07 |
URI: | https://orca.cardiff.ac.uk/id/eprint/141847 |
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