US3873903A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Volt-second balancing means for a high frequency switching power supply
Assignee: NCR Voyix Corp
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Filing: 1974-02-15
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Granted: 1975-03-25
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Expires: 1994-02-15
Abstract
Abstract In order to prevent potentially catastrophic overheating of power switching transistors driving the transformer primary winding in a high frequency inverter power supply, which overheating is a consequence of insidious movement along the B-H curve of the transformer resulting in unbalanced primary winding currents, the currents passing through the switching transistors are differentially compared to develop a signal representative of the imbalance. This error signal is utilized to alter the duty cycle of the drive to one side only of the primary winding. Actual, or tendency toward, core saturation is thereby avoided such that less conservatively rated components may be utilized while failure due to overheating as a result of current imbalance in the inverter transformer primary is avoided. This abstract is not to be taken either as a complete exposition of or as a limitation on the present invention. The full nature and extent of the invention may only be discerned by reference to the entire disclosure.
Inventors
- 👤 Philip W Koetsch
- 👤 Joseph C Jensen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 19:44
CPC Classifications
H; H02; H02M; H02M1/00; H02M1/40; H02M3/00; H02M3/22; H02M3/24; H02M3/28; H02M3/325; H02M3/335; H02M3/337; H02M3/3376; H02M3/3378
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
319 words
A HIGH FREQUENCY SWITCHING POWER SUPPLY COMPRISING: A. a source of d-c having a high side and a common side; B. a high frequency transformer including a primary winding having a center tap and first and second ends; C. means coupling said high side of said d-c source to said center tap; D. a first poWer switching transistor electrically disposed between said first end of said transformer and said common side of said d-c source; E. a second power switching transistor electrically disposed between said second end of said transformer and said common side of said d-c source; F. a clock pulse source; G. enabling means responsive to clock pulses for alternately developing drive pulses to said first and second power switching transistors: H. first and second current sensing means coupled, respectively, to said first and second power switching transistors for developing first and second current value signals corresponding to the instantaneous currents therethrough; I. compensating means responsive to the difference between the first and second current value signals to alter the duration of said drive pulses to said first power switching transistor, said compensating means including: i. a monostable multivibrator coupled to said enabling means to provide an enabling signal thereto when said monostable multivibrator times out, said monostable multivibrator starting a cycle of operation in response to a timing pulse derived from a clock pulse; and ii. a variable timing resistance, the duration of delay through said monostable multivibration being dependent upon said variable timing resistance, the valve of said variable timing resistance being responsive to the magnitude of the average difference between the first and second current value signals; and J. first and second integration means coupled, respectively, between said first current sensing means and said compensating means and between said second current sensing means and said compensating means whereby said compensating means responds to an average difference between the first and second current value signals.
Claim 2
Dependent Claim
319 words
A HIGH FREQUENCY SWITCHING POWER SUPPLY COMPRISING: A. a source of d-c having a high side and a common side; B. a high frequency transformer including a primary winding having a center tap and first and second ends; C. means coupling said high side of said d-c source to said center tap; D. a first poWer switching transistor electrically disposed between said first end of said transformer and said common side of said d-c source; E. a second power switching transistor electrically disposed between said second end of said transformer and said common side of said d-c source; F. a clock pulse source; G. enabling means responsive to clock pulses for alternately developing drive pulses to said first and second power switching transistors: H. first and second current sensing means coupled, respectively, to said first and second power switching transistors for developing first and second current value signals corresponding to the instantaneous currents therethrough; I. compensating means responsive to the difference between the first and second current value signals to alter the duration of said drive pulses to said first power switching transistor, said compensating means including: i. a monostable multivibrator coupled to said enabling means to provide an enabling signal thereto when said monostable multivibrator times out, said monostable multivibrator starting a cycle of operation in response to a timing pulse derived from a clock pulse; and ii. a variable timing resistance, the duration of delay through said monostable multivibration being dependent upon said variable timing resistance, the valve of said variable timing resistance being responsive to the magnitude of the average difference between the first and second current value signals; and J. first and second integration means coupled, respectively, between said first current sensing means and said compensating means and between said second current sensing means and said compensating means whereby said compensating means responds to an average difference between the first and second current value signals.
Claim 3
Dependent Claim
48 words
The high frequency switching power supply of claim 1 in which said variable resistance comprises a transistor and in which said compensating means includes a differential amplifier for receiving the integrated first and second current value signals, the output from said differential amplifier driving said variable resistance transistor.
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) | 1978-03-24 | 1978-09-23 | 1979-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-24 | 1982-09-23 | 1983-03-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-24 | 1986-09-23 | 1987-03-25 | $7700.00 | Window Closed / Lapsed |