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US4564837A
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US
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Circuit for monitoring the frequency of signal for controlling choppers of electric cars
Assignee: Mitsubishi Electric Corp
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Filing: 1983-01-03
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Granted: 1986-01-14
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Expires: 2003-01-03
Abstract
Abstract A circuit is disclosed for monitoring the frequency of a signal for controlling choppers of electric cars. The phase of the control signal is compared by a comparator with the phase of a reference frequency signal produced by a reference-frequency signal generator. When the phase difference which is greater than a predetermined value is sustained continuously for more than a predetermined period of time, an alarm is produced.
Inventors
- 👤 Toshiaki Awano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 10:50
CPC Classifications
H; H03; H03K; H03K5/00; H03K5/22; H03K5/26; G; G01; G01R; G01R25/00; G01R25/005
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
219 words
A circuit for monitoring the frequency of signal for controlling choppers of electric cars, comprising: means for generating a reference frequency signal which has a frequency which is an integer number of times that of said chopper control signal; means for generating a compare pulse signal responsive to the logical product between said reference frequency signal and said chopper control signal; means which divides the frequency of said reference frequency signal to generate a reference pulse signal of a nominal frequency for producing said chopper control signal; means which compares the phase between said compare pulse signal and said reference pulse signal to produce an error signal of a predetermined logic level when the phase difference between the two pulse signals becomes greater than a predetermined value; said comparator means comprising a first shift register having a plurality of stages which introduces one logic level that is shifted in one direction responsive to said compare pulse signal, and which introduces another logic level that is shifted in another direction responsive to said reference pulse signal, and gate means which produces the error signal when the output of the shift register continuously remains in a predetermined logic level for a predetermined period of time; and means for producing an alarm responsive to said error signal generated by said comparator means.
Claim 2
Dependent Claim
219 words
A circuit for monitoring the frequency of signal for controlling choppers of electric cars, comprising: means for generating a reference frequency signal which has a frequency which is an integer number of times that of said chopper control signal; means for generating a compare pulse signal responsive to the logical product between said reference frequency signal and said chopper control signal; means which divides the frequency of said reference frequency signal to generate a reference pulse signal of a nominal frequency for producing said chopper control signal; means which compares the phase between said compare pulse signal and said reference pulse signal to produce an error signal of a predetermined logic level when the phase difference between the two pulse signals becomes greater than a predetermined value; said comparator means comprising a first shift register having a plurality of stages which introduces one logic level that is shifted in one direction responsive to said compare pulse signal, and which introduces another logic level that is shifted in another direction responsive to said reference pulse signal, and gate means which produces the error signal when the output of the shift register continuously remains in a predetermined logic level for a predetermined period of time; and means for producing an alarm responsive to said error signal generated by said comparator means.
Claim 3
Dependent Claim
34 words
A monitoring circuit according to claim 1, wherein said gate means comprises an OR gate which becomes active when all inputs of preselected stages from said first shift register assume the same logic level.
Claim 4
Dependent Claim
71 words
A monitoring circuit according to claim 1, wherein said comparator means further comprises: a second shift register connected to said first shift register and having a plurality of stages, which introduces an output of said second shift register that is shifted in one direction; and said gate means produces the error signal in response to received preselected outputs having the same logic level as the stages of said second shift register.
Claim 5
Dependent Claim
39 words
A monitoring circuit according to claim 1, 2 or 3, wherein the compare pulse generating means comprises a flip-flop circuit which receives said reference frequency signal at the clock input, and the chopper control signal at the data input.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-01-13 | 1989-07-15 | 1990-01-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-01-13 | 1993-07-15 | 1994-01-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-01-13 | 1997-07-15 | 1998-01-14 | $7700.00 | Window Closed / Lapsed |