Intelligent solid state relay/breaker
First Claim
1. A solid-state power relay/breaker comprising:
- at least one solid-state power switching device, said power switching device connected to a load;
a bypass current sensing path coupled to said power switching device, said bypass current sensing path providing a bypass current proportional to current through said power switching device;
a signal processing circuit connected to said bypass current sensing path, said signal processing circuit sensing said bypass current in at least three different frequency bands to turn off said power switching device within a delayed time, said delayed time depending on said bypass current;
said power switching device being turned on by a first control signal and said bypass current sensing path being turned on by a second control signal, both of said control signals produced by said signal processing circuit in response to a command signal;
said first and said second control signals having controlled slew rate wherein turn-on slew rate is faster than turn-off slew rate.
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Accused Products
Abstract
A solid-state relay/breaker that can replace mechanical units to control any type of AC or DC load. Power MOSFETs or other transistors control a load current. A bypass current sensing path monitors MOSFET current and causes a shutdown through signal processing in the event of an over-current condition. This shutdown resembles that of a slow-blow fuse where the rate of shutdown is proportional to the value of the current. This prevents shutdown on momentary spikes or in-rush. In addition, temperature and internal power supply voltages are monitored to determine additional operational conditions where over-temperature or voltages out of range can also cause shutdown. The MOSFET and current sensing path are turned on and off in staggered timing with different slew rates to provide built-in hysteresis. The device can be manufactured in any type of package to match any type of environment or existing replacement requirement.
80 Citations
23 Claims
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1. A solid-state power relay/breaker comprising:
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at least one solid-state power switching device, said power switching device connected to a load; a bypass current sensing path coupled to said power switching device, said bypass current sensing path providing a bypass current proportional to current through said power switching device; a signal processing circuit connected to said bypass current sensing path, said signal processing circuit sensing said bypass current in at least three different frequency bands to turn off said power switching device within a delayed time, said delayed time depending on said bypass current; said power switching device being turned on by a first control signal and said bypass current sensing path being turned on by a second control signal, both of said control signals produced by said signal processing circuit in response to a command signal; said first and said second control signals having controlled slew rate wherein turn-on slew rate is faster than turn-off slew rate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A solid-state relay/breaker having over-current characteristics of a slow-blow fuse of the type used to control high power AC or DC loads, the relay/breaker being commanded to turn on or off by a digital control signal comprising:
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at least one pair of MOSFET power transistors controlling a load current; a current sense path sensitive to at least three different frequency bands providing a feedback value proportional to said load current, said current sense path being sensitive to both AC and DC load currents; a signal processing circuit coupled to said current sense path for turning off said MOSFET power transistors after a delay using a pair of control signals when said load current exceeds a predetermined threshold, said delay being related to said load current, said control signals having a fast turn-on slew rate and a slower turn-off slew rate; said signal processing circuit also acting in response to a turn-on/turn-off command to switch said MOSFET power transistors and said current sense path off or on, switching of said MOSFET power transistors and said current sense path occurring with staggered timing. - View Dependent Claims (16, 17, 18, 19)
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20. A method for providing a slow-blow solid-state relay breaker action comprising the steps of:
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providing a MOSFET power switch transistor pair to switch current from a load; providing a current sense transistor to provide a bypass current proportional to load current flowing through said MOSFET power switch transistor pair; providing signals in at least three different frequency bands for determining if said bypass current is within range; providing delayed turnoff to said MOSFET power switch transistor pair using a first control signal when said bypass current exceeds a predetermined threshold, said delayed turnoff related to said bypass current; turning on said MOSFET power switch transistor pair using a second control signal before turning on said current sense transistor when starting said solid-state relay/breaker; and wherein said first control signal has a faster slew-rate than said second control signal. - View Dependent Claims (21, 22, 23)
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Specification