EP0739085A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Compensation for input voltage variation in an electric motor drive
Assignee: SWITCHED RELUCTANCE DRIVES Ltd
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Filing: 1996-04-09
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Granted: —
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Expires: 2016-04-09
Abstract
Abstract The present invention employs digital circuitry to compensate for variations in DC link voltage transmitted to a switched reluctance machine. The digital voltage compensation system of the present invention periodically samples the DC link voltage and actual rotor speed, then supplies the samples in digital form to a microcontroller that derives a compensated speed signal to compensate for changes in DC link voltage.
Inventors
- 👤 Paul Donald Webster
- 👤 Geoffrey Thomas Brown
- 👤 David Mark Sugden
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 19:29
CPC Classifications
H; H02; H02P; H02P7/00; H02P7/06; H02P29/00; H02P29/02; H02P29/024; H02P29/026; H02P31/00; Y; Y10; Y10S; Y10S388/00; Y10S388/90; Y10S388/902
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
127 words
A method for compensating for deviations of actual DC link voltage from a predetermined DC link voltage applied to an electric machine drive, which includes an electric machine having a rotor and a controller for controlling the machine in response to a speed signal, the method comprising the steps of: periodically sampling the actual DC link voltage and converting the sampled DC link voltage into a digital link voltage representation; periodically sampling the actual rotor speed and converting the sampled rotor speed to a digital speed representation; modifying the digital speed representation according to the digital link voltage representation to produce a compensated speed signal; and transmitting the compensated speed signal to the electric machine controller and using the compensated speed signal in control of the machine.
Claim 2
Dependent Claim
32 words
A method as claimed in claim 1 in which the digital speed representation is multiplied by a compensation factor, generated from the digital link voltage representation, to produce the compensated speed signal.
Claim 3
Dependent Claim
26 words
A method as claimed in claim 2, in which the compensation factor corresponds to the predetermined DC link voltage divided by the actual DC link voltage.
Claim 4
Independent Claim
26 words
A method as claimed in any of claims 1 to 3 in which each digital link voltage representation is an average of a plurality of samples.
Claim 5
Independent Claim
25 words
A method as claimed in any of claims 1 to 4 including limiting the digital dc link voltage representation to be within a predetermined range.
Claim 6
Independent Claim
23 words
A method as claimed in any of claims 1 to 5 including limiting the digital speed representation to be within a predetermined range.
Claim 7
Dependent Claim
109 words
A compensation system for compensating for a deviation of an actual DC link voltage from a predetermined DC link voltage in an electric drive which includes an electric machine having a rotor, the system comprising: means for sampling the actual DC link voltage periodically and converting the sampled DC link voltage into a digital link voltage representation; means for sampling an actual rotor speed periodically and converting the sampled rotor speed into a digital speed representation; means for modifying the digital speed representation according to the digital link voltage representation to produce a compensated speed signal, and means for controlling the machine in accordance with the compensated speed signal.
Claim 8
Dependent Claim
38 words
A system as claimed in claim 7 in which the means for sampling the actual DC link voltage are operable to produce, as the digital link voltage representation, an average of a plurality of sampled DC link voltages.
Claim 9
Dependent Claim
34 words
A system as claimed in claim 7 or 8 in which the means for modifying the digital speed representation comprise means for limiting the digital link voltage representation to be within a predetermined range.
Claim 10
Dependent Claim
32 words
A system as claimed in claim 9 in which the means for modifying the digital speed representation further comprise means for limiting the digital speed representation to be within a predetermined range.
Claim 11
Dependent Claim
37 words
A system as claimed in claim 7, including: means for limiting the sampled DC link voltage to be within a predetermined range; means for accumulating a plurality of voltage samples; and means for averaging the voltage samples.
Claim 12
Dependent Claim
163 words
A system as claimed in claim 8 in which the means for generating the compensated rotor speed signal further comprise: digital means for limiting the voltage sampled by making all voltage samples below a lower level equal to the lower level and all voltage samples above an upper level equal to the upper level; digital means for averaging and rounding a plurality of the voltage samples; means for multiplying the averaged and rounded voltage samples to produce a compensation factor; means for detecting the actual rotor speed; digital means for limiting the digital speed representation for values above a predetermined threshold; digital means for multiplying the digital speed representation by a compensation factor to produce an interim rotor speed signal; means for dividing the interim rotor speed signal by a predetermined divisor to produce a scaled interim rotor speed signal; and means for limiting the scaled interim rotor speed signals which are greater than a predetermined amount to produce the compensated speed signal.
Claim 13
Dependent Claim
20 words
A system as claimed in claim 12 in which the means for generating the compensated speed signal include a microprocessor.
References Cited (Backward Citations)
No citation records indexed.
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