Agile Systems, Inc.

Derek C Schuurman

Robert Gordon Lankin

Richard J Hellinga

A multiple current path device, for carrying electric current to and conducting heat from an electronic circuit, comprising an optional heat sink, a plurality of conducting substrates forming several electrically insulated current conductors, a thermally conductive, electrically insulating first layer, bonding each conducting substrate and the heat sink, and a plurality of electronic or electric components bonded to the substrates.

Bus bar heat sink

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.

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Drayton, Canada

Derek C Schuurman