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:
Oct. 04, 1988
Filed:
Apr. 13, 1987
Haruyoshi Mori, Hyogo, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
The invention relates to technology to minimize power for suppressing ON base current to a transistor. In a base drive circuit of transistor, current is supplied to base of first and second transistors connected in series to DC power source, and the transistors are rendered on or off. The base drive circuit comprises a current transformer using as a primary winding an AC bus connected in parallel between the joint of the first and second transistors and having a secondary winding energized by current of the primary winding and inducing current; a switching circuit including a first rectifier element for rectifying current induced in any portion of the secondary winding of the current transformer, a first switching element for supplying the rectified current outputted from the first rectifier element to the base of any of the first and second transistors, an initial current supply circuit for supplying initial current to the base of the transistor supplied with the rectified current in superposition of the current flowing through the first switching element, and a second switching element in bypass connection so as not to supply the rectified current to the base of the transistor; and a second rectifier element for rectifying current induced in any other portion of the secondary winding of the current transformer, and an overvoltage suppression circuit comprising a reset circuit connected in series to the second rectifier element for applying reset to the core of the current transformer.