EP0123807A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Driving and detection of back EMF in permanent magnet step motors
Assignee: International Business Machines Corp
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Filing: 1984-02-20
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Granted: —
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Expires: 2004-02-20
Abstract
Abstract The invention relates to a drive and detection circuit for a step motor of the type having a permanent magnet rotor and two sets of stator windings (21-23, 25-27, 31-33, 35-37). The circuit includes a supply voltage for the step motor, drive means (41, 43, 45, 47) connected to the supply voltage for providing excitation of the stator windings, and detection means for detecting the value of the back EMF induced in each set of windings by the permanent magnet rotor. The drive means provides orthogonal excitation of the stator windings whereby only one set of windings is excited at any instant. According to one embodiment of the invention the drive means operates to dampen any residual current flowing in each set of windings after the termination of excitation so that there is no residual current flowing in the set of windings when the detection means detects a zero value of the back EMF induced in the set of windings.
Inventors
- 👤 Victor David Hair
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 23:37
CPC Classifications
G; G04; G04C; G04C3/00; G04C3/14; G04C3/143; H; H02; H02P; H02P8/00; H02P8/14
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
95 words
A drive and detection circuit for a step motor of the type having a permanent magnet rotor (11) and two sets of stator windings (21-23,25-27,31-33,35-37) comprising a supply voltage for said step motor, drive means (41,43,45,47,51,53,55,57,) connected to said supply voltage for providing excitation of said stator windings, and detection means (211,213,215,217) for detecting the value of the back EMF induced in each set of windings by the permanent magnet rotor, characterised in that said drive means provides orthogonal excitation of said stator windings whereby only one set of windings is excited at any instant.
Claim 2
Dependent Claim
95 words
A drive and detection circuit for a step motor of the type having a permanent magnet rotor (11) and two sets of stator windings (21-23,25-27,31-33,35-37) comprising a supply voltage for said step motor, drive means (41,43,45,47,51,53,55,57,) connected to said supply voltage for providing excitation of said stator windings, and detection means (211,213,215,217) for detecting the value of the back EMF induced in each set of windings by the permanent magnet rotor, characterised in that said drive means provides orthogonal excitation of said stator windings whereby only one set of windings is excited at any instant.
Claim 3
Dependent Claim
65 words
A drive and detection circuit as claimed in claim 1 characterised in that said drive means (51,53,55,57) operates to dampen any residual current flowing in each set of windings after the termination of excitation so that there is no residual current flowing in said set of windings when said detection means detects a zero value of the back EMF induced in said set of windings.
Claim 4
Dependent Claim
83 words
A drive and detection circuit as claimed in claim 2 characterised in that said drive means comprises for each set of windings a set of four switching devices (41,43,45,47) connected in an H configuration circuit and adapted to provided excitation current to said set of windings, and diode devices (51,53,55,57) connected across said switching devices so as to dampen any current induced in said set of windings when said switching devices are operated to interrupt the supply of excitation current to said windings.
Claim 5
Dependent Claim
33 words
A drive and detection circuit as claimed in any one of the preceding claims characterised in that said detector means comprises comparator means (215,217) for comparing said back EMF with a reference voltage.
Claim 6
Dependent Claim
41 words
A drive and detection circuit as claimed in any one of the preceding claims characterised in that said drive means comprises current responsive means for limiting the current through any of said windings in order to prevent overheating of said windings.
Claim 7
Dependent Claim
31 words
A drive and detection circuit as claimed in any one of the preceding claims comprising a programmed computer (221) for controlling the operation of said drive means and said detector means.
Claim 8
Independent Claim
108 words
A method of operating a step motor of the type having a permanent magnet rotor (11) and two sets of stator windings (21,23,25,27,31,33,35,37) comprising selectively connecting a supply voltage to each set of stator windings so as to excite said windings in a predetermined sequence and detecting the value of the back EMF induced in each set of windings by said permanent magnet rotor and using the detection of selected values of said back EMF in order to control the excitation of said sets of windings, characterised in that said sets of windings are excited orthogonally so that only one set of windings is excited at any instant.
Claim 9
Independent Claim
108 words
A method of operating a step motor of the type having a permanent magnet rotor (11) and two sets of stator windings (21,23,25,27,31,33,35,37) comprising selectively connecting a supply voltage to each set of stator windings so as to excite said windings in a predetermined sequence and detecting the value of the back EMF induced in each set of windings by said permanent magnet rotor and using the detection of selected values of said back EMF in order to control the excitation of said sets of windings, characterised in that said sets of windings are excited orthogonally so that only one set of windings is excited at any instant.
References Cited (Backward Citations)
No citation records indexed.
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