Patents by Inventor Kai Johansson

Kai Johansson has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 8368384
    Abstract: A method of reducing thermal stresses of a semiconductor component in a frequency converter, an arrangement in a frequency converter, and a frequency converter, wherein the semiconductor component is attached to a cooling element for cooling the semiconductor component and one or more resistive elements are attached to the cooling element. In the method, the cooling element is heated by the one or more resistive elements attached thereto by supplying current from the frequency converter through the one or more resistive elements for obtaining an elevated lowest temperature for the semiconductor component and thereby reducing the amount of temperature change between the highest and the lowest temperatures in the semiconductor component during use of the frequency converter.
    Type: Grant
    Filed: September 11, 2008
    Date of Patent: February 5, 2013
    Assignee: ABB OY
    Inventors: Kjell Ingman, Kari Tikkanen, Tomi Väisälä, Kai Johansson
  • Publication number: 20100060328
    Abstract: A method of reducing thermal stresses of a semiconductor component in a frequency converter, an arrangement in a frequency converter, and a frequency converter, wherein the semiconductor component is attached to a cooling element for cooling the semiconductor component and one or more resistive elements are attached to the cooling element. In the method, the cooling element is heated by the one or more resistive elements attached thereto by supplying current from the frequency converter through the one or more resistive elements for obtaining an elevated lowest temperature for the semiconductor component and thereby reducing the amount of temperature change between the highest and the lowest temperatures in the semiconductor component during use of the frequency converter.
    Type: Application
    Filed: September 11, 2008
    Publication date: March 11, 2010
    Applicant: ABB Oy
    Inventors: Kjell INGMAN, Kari Tikkanen, Tomi Vaisala, Kai Johansson
  • Patent number: 5309086
    Abstract: The invention relates to a current measuring transducer operating on the compensation principle, comprising two magnetic cores (C1, C2) with windows; windings wound thereon for both a current (Ip) to be measured and for a compensation current (Is); and means (Um, Nm, R1, D, IA) for generating the compensation current and adjusting the magnitude thereof. To compensate for induced interference voltages, a further winding (Nc1, Nc2) is arranged about both magnetic cores of the current transducer. To widen the frequency band, the windings (Nc1, Nc2) are series-connected in a closed loop through a frequency-dependent impedance (Z).
    Type: Grant
    Filed: March 25, 1993
    Date of Patent: May 3, 1994
    Assignee: ABB Stromberg Drives OY
    Inventors: Kai Johansson, Matti Lounila, Juha Kokkonen