Browse Prior Art Database

Method for Testing H Drives

IP.com Disclosure Number: IPCOM000049190D
Original Publication Date: 1982-May-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 70K

Publishing Venue

IBM

Related People

Voss, C: AUTHOR

Abstract

Proposed is a method of sensing and thereby determining if an H-drive unit is shorted, opened, or is actually delivering power to a load.

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Method for Testing H Drives

Proposed is a method of sensing and thereby determining if an H-drive unit is shorted, opened, or is actually delivering power to a load.

Illustrated in Fig. 2 is a typical symmetrical driver 10 commonly referred to as an H-drive. Power Darlingtons Q1 and Q4 with commutating diode Dl establish a forward current path. In a similar manner, Darlingtons Q2 and Q3 with commutating diode D2 determine the reverse path of current. In operation, both paths are never on simultaneously.

The sense element, as illustrated best in Fig. 1, comprises a ferrite core 11 with two independent and opposing coils 12 and 13, respectively. Two Hall- effect devices H1 and H2 are placed in air gaps in the core, and positioned such that each responds only to the coil generating the magnetic flux properly oriented to it. (The Hall-effect devices utilized respond only to magnetic fields oriented in a specific direction with respect to itself. The Hall devices may be provided with hysteresis and appropriate drive circuitry. Logic zero, in the present example, defines the presence of a magnetic field.)

The detection method consists of sensing magnetic fields, hence currents, in the two legs or two paths of the H-drive. For the forward mode, Hall-effect device H2 will sense the presence of a magnetic field, whereas Hall-effect device H1 will not. The opposite is true for the reverse mode of current flow. If either Hall- effect device H1 or H2 is not logic "zero" duri...