US4653285A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Self-calibrating control methods and systems for refrigeration systems
Assignee: General Electric Co
•
Filing: 1985-09-20
•
Granted: 1987-03-31
•
Expires: 2005-09-20
Abstract
Abstract Disclosed are refrigeration system control systems and methods for compressor motor protection and defrost control. The disclosed systems and methods are generic in the sense that they are self-calibrating and so may be employed in a variety of different air conditioner or heat pump models of different sizes and capacities, without being specifically tailored for a particular model. The disclosed systems and methods sense loading on the compressor and evaporator fan motors, preferably by sensing the voltage across the capacitor-run winding of an AC induction motor and normalizing with respect to line voltage. The self-calibrating capability is implemented by taking advantage of the changing loads as a function of time on both the compressor and fan motors during both normal and abnormal operation of a refrigeration system. In overview, a reference value of motor loading is established for each motor at certain times during an ON cycle. At later times the then-prevailing motor loading is compared to the stored reference in order to provide a basis for control decisions. The ratio of capacitor-run winding voltage to line voltage is an advantageous indicator of motor loading. In one embodiment, a reference ratio of capacitor-run winding voltage to line voltage is established, and at later times is compared to the then-prevailing ratio of capacitor-run winding voltage to line voltage.
Inventors
- 👤 Walter J. Pohl
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:21
CPC Classifications
F; F25; F25B; F25B49/00; F25B49/02; F25B49/025; F25D; F25D21/00; F25D21/002; F25D21/006; H; H02; H02P; H02P29/00; H02P29/02; H02P29/032
Claims Analysis
Total Claims: 44
Claim 1
Independent Claim
131 words
A self-calibrating method for protecting a motor driving a refrigerant compressor in a refrigeration system which is cycled ON and OFF during operation, said method comprising: determining a compressor motor reference loading at a relatively early time during a compressor ON cycle by allowing a stabilization interval to elapse during which the refrigeration system stabilizes and the compressor motor is still lightly loaded, and then sensing and storing at least a representation of compressor motor loading as the reference loading; and thereafter, during each ON cycle, at least periodically sensing at least a representation of prevailing compressor motor loading, comparing the prevailing loading to the reference loading, and de-energizing the compressor motor if the prevailing loading exceeds a high load threshold loading established as a predetermined function of the reference loading.
Claim 2
Dependent Claim
131 words
A self-calibrating method for protecting a motor driving a refrigerant compressor in a refrigeration system which is cycled ON and OFF during operation, said method comprising: determining a compressor motor reference loading at a relatively early time during a compressor ON cycle by allowing a stabilization interval to elapse during which the refrigeration system stabilizes and the compressor motor is still lightly loaded, and then sensing and storing at least a representation of compressor motor loading as the reference loading; and thereafter, during each ON cycle, at least periodically sensing at least a representation of prevailing compressor motor loading, comparing the prevailing loading to the reference loading, and de-energizing the compressor motor if the prevailing loading exceeds a high load threshold loading established as a predetermined function of the reference loading.
Claim 3
Dependent Claim
21 words
A method in accordance with claim 1, wherein the stabilization interval is within the range of five seconds to five minutes.
Claim 4
Dependent Claim
44 words
A method in accordance with claim 1, which further comprises, in the event the compressor motor has been de-energized as a result of prevailing compressor motor loading increasing above the high load threshold loading, re-energizing the motor after a cooling-off time interval has elapsed.
Claim 5
Dependent Claim
68 words
A method in accordance with claim 1, which further comprises allowing a compressor loading interval to elapse during which the compressor can be expected to become loaded in the absence of excessive evaporator frost, and then sensing compressor motor loading and initiating a precautionary defrosting operation in the event compressor motor loading is below a normal load threshold loading established as a predetermined function of the reference loading.
Claim 6
Dependent Claim
19 words
A method in accordance with claim 4, wherein the compressor loading interval is in the order of ten minutes.
Claim 7
Dependent Claim
166 words
A self-calibrating method for protecting a single-phase induction motor supplied from an AC power line, of the type including a capacitor-run winding, and driving a refrigerant compressor in a refrigeration system which is cycled ON and OFF during operation, said method comprising: determining, as an indicator of motor loading, a compressor motor reference ratio at a relatively early time during a compressor ON cycle by allowing a stabilization interval to elapse during which the refrigeration system stabilizes and the compressor motor is still lightly loaded, then sensing the ratio of capacitor-run winding voltage to line voltage, and storing at least a representation of the sensed ratio as the compressor motor reference ratio; and thereafter, during each ON cycle, at least periodically sensing the prevailing ratio of capacitor-run winding voltage to line voltage, comparing the prevailing ratio to the compressor motor reference ratio, and de-energizing the compressor motor if the prevailing ratio is below a high-load threshold ratio established as a predetermined fraction of the reference ratio.
Claim 8
Dependent Claim
166 words
A self-calibrating method for protecting a single-phase induction motor supplied from an AC power line, of the type including a capacitor-run winding, and driving a refrigerant compressor in a refrigeration system which is cycled ON and OFF during operation, said method comprising: determining, as an indicator of motor loading, a compressor motor reference ratio at a relatively early time during a compressor ON cycle by allowing a stabilization interval to elapse during which the refrigeration system stabilizes and the compressor motor is still lightly loaded, then sensing the ratio of capacitor-run winding voltage to line voltage, and storing at least a representation of the sensed ratio as the compressor motor reference ratio; and thereafter, during each ON cycle, at least periodically sensing the prevailing ratio of capacitor-run winding voltage to line voltage, comparing the prevailing ratio to the compressor motor reference ratio, and de-energizing the compressor motor if the prevailing ratio is below a high-load threshold ratio established as a predetermined fraction of the reference ratio.
Claim 9
Dependent Claim
21 words
A method in accordance with claim 6, wherein the stabilization interval is within the range of five seconds to five minutes.
Claim 10
Dependent Claim
29 words
A method in accordance with claim 6, wherein the predetermined fraction by which the high-load threshold ratio is established is within the range of 0.75-0.80, times the reference ratio.
Claim 11
Dependent Claim
29 words
A method in accordance with claim 7, wherein the predetermined fraction by which the high-load threshold ratio is established is within the range of 0.75-0.80 times the reference ratio.
Claim 12
Dependent Claim
48 words
A method in accordance with claim 6, which further comprises, in the event the motor has been de-energized as a result of the prevailing ratio of capacitor-run winding voltage to line voltage falling below the high-load threshold ratio, re-energizing the motor after a cooling-off time interval has elapsed.
Claim 13
Dependent Claim
75 words
A method in accordance with claim 6, which further comprises allowing a compressor loading interval to elapse during which the compressor can be expected to become loaded in the absence of excessive evaporator frost, then sensing the prevailing ratio of compressor capacitor-run winding voltage to line voltage and initiating a precautionary defrosting operation in the event the sensed ratio is above a normal load threshold ratio established as a predetermined fraction of the reference ratio.
Claim 14
Dependent Claim
19 words
A method in accordance with claim 11, wherein the compressor loading interval is in the order of ten minutes.
Claim 15
Dependent Claim
27 words
A method in accordance with claim 11, wherein the predetermined fraction by which the normal load threshold ratio is established is approximately 0.95 of the reference ratio.
Claim 16
Dependent Claim
27 words
A method in accordance with claim 12, wherein the predetermined fraction by which the normal load threshold ratio is established is approximately 0.95 of the reference ratio.
Claim 17
Dependent Claim
66 words
A self-calibrating method in accordance with claim 14, which further comprises determining whether the compressor motor has failed to start at the beginning of an ON cycle by: allowing a compressor motor equilibrium speed interval to elapse; and then sensing the prevailing ratio of capacitor-run winding voltage to line voltage, and de-energizing the compressor motor if the prevailing ratio is below a predetermined locked rotor ratio.
Claim 18
Dependent Claim
19 words
A method in accordance with claim 15, wherein the predetermined locked rotor ratio is in the order of 0.5.
Claim 19
Dependent Claim
18 words
A method in accordance with claim 16, wherein the compressor motor equilibrium speed interval is approximately two seconds.
Claim 20
Dependent Claim
22 words
A method in accordance with claim 15, which further comprises allowing the compressor motor to attempt a restart after a cool-down interval.
Claim 21
Dependent Claim
15 words
A method in accordance with claim 17, wherein the cool-down interval is approximately 2.5 minutes.
Claim 22
Dependent Claim
15 words
A method in accordance with claim 17, which comprises limiting the number of restart attempts.
Claim 23
Dependent Claim
168 words
A self-calibrating control system for a refrigeration system including a refrigerant compressor and a compressor motor for driving the compressor, said control system comprising: a switching element for cycling the refrigeration system ON and OFF by energizing and de-energizing the compressor motor; a sensing element for sensing at least a representation of compressor motor loading; means connected to said sensing element for determining a compressor motor reference loading at a relatively early time during a compressor ON cycle by allowing a stabilization interval to elapse during which the refrigeration system stabilizes and the compressor motor is still lightly loaded, and then storing at least a representation of motor loading as the reference; and means connected to said sensing and switching elements for thereafter, during each ON cycle, at least periodically comparing at least a representation of prevailing compressor motor loading to the reference loading, and de-energizing the compressor motor if the prevailing loading exceeds a high load threshold loading established as a predetermined function of the reference loading.
Claim 24
Dependent Claim
168 words
A self-calibrating control system for a refrigeration system including a refrigerant compressor and a compressor motor for driving the compressor, said control system comprising: a switching element for cycling the refrigeration system ON and OFF by energizing and de-energizing the compressor motor; a sensing element for sensing at least a representation of compressor motor loading; means connected to said sensing element for determining a compressor motor reference loading at a relatively early time during a compressor ON cycle by allowing a stabilization interval to elapse during which the refrigeration system stabilizes and the compressor motor is still lightly loaded, and then storing at least a representation of motor loading as the reference; and means connected to said sensing and switching elements for thereafter, during each ON cycle, at least periodically comparing at least a representation of prevailing compressor motor loading to the reference loading, and de-energizing the compressor motor if the prevailing loading exceeds a high load threshold loading established as a predetermined function of the reference loading.
Claim 25
Dependent Claim
22 words
A control system in accordance with claim 21, wherein the stabilization interval is within the range of five seconds to five minutes.
Claim 26
Dependent Claim
44 words
A control system in accordance with claim 21, which further comprises means for re-energizing the motor after a cooling-off time interval has elapsed in the event the compressor motor has been de-energized as a result of prevailing loading exceeding the high load threshold loading.
Claim 27
Dependent Claim
68 words
A control system in accordance with claim 21, which further comprises means for allowing a compressor loading interval to elapse during which the compressor can be expected to become loaded in the absence of excessive evaporator frost, and then initiating a precautionary defrosting operation in the event the prevailing compressor motor loading is below a normal load threshold loading established as a predetermined function of the reference loading.
Claim 28
Dependent Claim
20 words
A control system in accordance with claim 24, wherein the compressor loading interval is in the order of ten minutes.
Claim 29
Dependent Claim
210 words
A self-calibrating control system for a refrigeration system including a refrigerant compressor and a compressor motor for driving the compressor, the compressor motor being an AC induction motor of the type including a capacitor-run winding and supplied from an AC power line, said control system comprising: a switching element for cycling the refrigeration system ON and OFF by energizing and de-energizing the compressor motor; sensing means for sensing the ratio of capacitor-run winding voltage to AC line voltage; means connected to said sensing means for determining, as an indicator of motor loading, a compressor motor reference ratio at a relatively early time during a compressor ON cycle by allowing a stabilization interval to elapse during which the refrigeration system stabilizes and the compressor motor is still lightly loaded, and then storing at least a representation of the ratio of capacitor-run winding voltage to line voltage as the compressor motor reference ratio; and means connected to said sensing means and said switching element for thereafter, during each ON cycle, at least periodically comparing the prevailing ratio of capacitor-run winding voltage to line voltage to the reference ratio, and de-energizing the compressor motor if the prevailing ratio is below a high-load threshold ratio established as a predetermined fraction of the reference ratio.
Claim 30
Dependent Claim
210 words
A self-calibrating control system for a refrigeration system including a refrigerant compressor and a compressor motor for driving the compressor, the compressor motor being an AC induction motor of the type including a capacitor-run winding and supplied from an AC power line, said control system comprising: a switching element for cycling the refrigeration system ON and OFF by energizing and de-energizing the compressor motor; sensing means for sensing the ratio of capacitor-run winding voltage to AC line voltage; means connected to said sensing means for determining, as an indicator of motor loading, a compressor motor reference ratio at a relatively early time during a compressor ON cycle by allowing a stabilization interval to elapse during which the refrigeration system stabilizes and the compressor motor is still lightly loaded, and then storing at least a representation of the ratio of capacitor-run winding voltage to line voltage as the compressor motor reference ratio; and means connected to said sensing means and said switching element for thereafter, during each ON cycle, at least periodically comparing the prevailing ratio of capacitor-run winding voltage to line voltage to the reference ratio, and de-energizing the compressor motor if the prevailing ratio is below a high-load threshold ratio established as a predetermined fraction of the reference ratio.
Claim 31
Dependent Claim
22 words
A control system in accordance with claim 26, wherein the stabilization interval is within the range of five seconds to five minutes.
Claim 32
Dependent Claim
30 words
A control system in accordance with claim 26, wherein the predetermined fraction by which the high-load threshold ratio is established is on the order of 0.75-0.80 times the reference ratio.
Claim 33
Dependent Claim
30 words
A control system in accordance with claim 27, wherein the predetermined fraction by which the high-load threshold ratio is established is on the order of 0.75-0.80 times the reference ratio.
Claim 34
Dependent Claim
43 words
A control system in accordance with claim 26, which further comprises means for re-energizing the motor after a cooling-off time interval has elapsed in the event the motor has been de-energized as a result of the prevailing ratio falling below the high-load threshold.
Claim 35
Dependent Claim
74 words
A control system in accordance with claim 26, which further comprises means for allowing a compressor loading interval to elapse during which the compressor can be expected to become loaded in the absence of excessive evaporator frost, and then initiating a precautionary defrosting operation in the event the prevailing ratio of compressor capacitor-run winding voltage to line voltage is above a normal load threshold ratio established as a predetermined fraction of the reference ratio.
Claim 36
Dependent Claim
20 words
A control system in accordance with claim 30, wherein the compressor loading interval is in the order of ten minutes.
Claim 37
Dependent Claim
28 words
A control system in accordance with claim 30, wherein the predetermined fraction by which the normal load threshold ratio is established is approximately 0.95 of the reference ratio.
Claim 38
Dependent Claim
28 words
A control system in accordance with claim 32, wherein the predetermined fraction by which the normal load threshold ratio is established is approximately 0.95 of the reference ratio.
Claim 39
Dependent Claim
63 words
A self-calibrating control system in accordance with claim 34, which further comprises means for determining whether the compressor motor has failed to start at the beginning of an ON cycle by: allowing a compressor motor equilibrium speed interval to elapse; and de-energizing the compressor motor if the prevailing ratio of capacitor-run winding voltage to line voltage is below a predetermined locked rotor ratio.
Claim 40
Dependent Claim
20 words
A control system in accordance with claim 35, wherein the predetermined locked rotor ratio is in the order of 0.5.
Claim 41
Dependent Claim
19 words
A control system in accordance with claim 36, wherein the compressor motor equilibrium speed interval is approximately two seconds.
Claim 42
Dependent Claim
23 words
A control system in accordance with claim 35, which further comprises allowing the compressor motor to attempt a restart after a cool-down interval.
Claim 43
Dependent Claim
16 words
A control system in accordance with claim 37, wherein the cool-down interval is approximately 2.5 minutes.
Claim 44
Dependent Claim
18 words
A control system in accordance with claim 37, which comprises means for limiting the number of restart attempts.
References Cited (Backward Citations)
US3671830A
Cited
US4038061A
Cited
US4079432A
Cited
US4104888A
Cited
US4102391A
Cited
US4123792A
Cited
US4176396A
Cited
US4197532A
Cited
US4196462A
Cited
US4215554A
Cited
US4251872A
Cited
US4240072A
Cited
US4286303A
Cited
US4253130A
Cited
US4299095A
Cited
US4474024A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-03-30 | 1990-09-29 | 1991-03-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-03-30 | 1994-09-29 | 1995-03-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-03-30 | 1998-09-29 | 1999-03-31 | $7700.00 | Window Closed / Lapsed |