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:
Feb. 23, 1999
Filed:
Jun. 11, 1997
Derek C Schuurman, Drayton, CA;
Agile Systems, Inc., Waterloo, CA;
Abstract
The approach to measuring load current in a multi-phase bridge inverter circuit connected to a multiphase load involves placing a single current sense resistor in series with the inverter circuit and power supply. The current flow through the sense resistor is sampled during a portion of the switching cycle wherein the inverter is configured to enable current flowing through the multi-phase load to flow through the sense resistor. Typically, this will occur during a portion of the switching cycle (e.g. PWM cycle) wherein the load is being actively driven. For a 120.degree., 3-phase, 6-step commutation sequence typically used to control a d.c. brushless servo motor, the sampled current is a time-multiplexed measure of the current flow through each load phase. The same sense resistor is also used for indicating a short circuit condition by comparing the voltage across the resistor to a reference voltage.