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:
Dec. 20, 1994
Filed:
Sep. 08, 1992
Masanori Fukunaga, Fukuoka, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
Free wheeling diodes are protected against an overcurrent. When counter electromotive forces E.sub.VU and E.sub.WU established in a tri-phase motor cause regenerative currents I.sub.V1 and I.sub.W1 to flow to transistors Q4 and Q6, and to a protection diode D2, it is decided that the protection diode D2 is in overcurrent state. In response to the decision, the transistors Q4 and Q6 are turned off, which allows that regenerative currents I.sub.V2 and I.sub.W2 flow in protection diodes D3 and D5 because of the counter electromotive forces E.sub.VU and E.sub.WU. The energies of the regenerative currents I.sub.V2 and I.sub.W2 are regenerated at a capacitor C. Thus, since a regenerative current which once passed by only one protection diode is divided into two current flows into two protection diodes, the overcurrent state is terminated.