The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 14, 2017
Filed:
Sep. 05, 2014
Abb Oy, Helsinki, FI;
Samuli Heikkilä, Helsinki, FI;
ABB Technology Oy, Helsinki, FI;
Abstract
A method is provided for balancing voltages of a DC link of a multi-level inverter, where the DC link is divided into two halves by a neutral point connection. The method includes injecting a periodic common-mode voltage injection signal to a common-mode voltage reference and a periodic power injection signal to a power reference of the inverter. The power injection signal has the same frequency as the common-mode voltage injection signal. A phase shift between the common-mode voltage injection signal and the power injection signal is constant. The amplitude of at least one of the common-mode voltage injection signal and the power injection signal is controlled on the basis of a difference between voltages over the two halves of the DC link. An apparatus is also provided for implementing the method.