Patent Application
20130262003
The present invention relates to power distribution systems, and more particularly to measuring and comparing electrical current passing through such power distribution systems and a method for measuring and comparing the current.
Current transformers are typically employed in aircraft primary power distribution systems to monitor the integrity of high electric current paths. The current transformers are expensive, heavy and require extra wiring. The large, external current transformers are mounted over portions of high power wiring harnesses and require amplifiers for operation. In an effort to detect wiring failure, two current transformers are typically needed, with one on each end of a conductor, to measure the possible difference between current flowing in and out of the harness section, thereby doubling the effort needed.
According to one embodiment, a current measurement and comparing assembly for a power distribution system includes a solid state contactor module having a control section and a power section, wherein the power section includes at least one solid state switch. Also included is a current sensor disposed in the control section and in operable communication with the at least one solid state switch, wherein the current sensor distributes current data to a switch control configured to control the at least one solid state switch and distributes current data to a current measurement and comparison circuit.
According to another embodiment, a method of measuring and comparing current of a power distribution system is provided. The method includes integrating a current sensor within a control section of a solid state contactor module having at least one solid state switch. Also included is distributing current data to a switch control configured to control the at least one solid state switch. Further included is distributing current data via an input line to a current measurement and comparison circuit. Yet further included is comparing the current data received from the input line to a first summed current differential signal from at least one downstream solid state switch, wherein a current difference is detected.
The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
Referring to
The power section 20 includes at least one solid state switch 14. It shall be understood that any type of solid state switch could be used and in one embodiment, the solid state switch is MOSFET switch. A temperature sensor 36 is in communication with the isolated interface 22 and may alert the control section 18 of excessive temperature conditions within the power section 20, for example. A clamping module 38 protects the solid state switch 14 against overvoltage conditions (e.g., lighting, inductive load backfeed, etc.). A secondary protection module 40 protects the load 13 against excessive current conditions.
The current sensor 34 is integrally formed with the control section 18 and serves to provide various components of the control section 18 with information necessary to determine whether the circuit of the solid state switch 14 requires breaking or tripping, thereby performing circuit breaking functionality. The current sensor 34 measures current information from the at least one switch 14 and transmits the current data along a plurality of branches to various components of the power distribution system 10. In addition to transmitting such current data to the switch control logic module 30, as described above, the current data is sent to a current measurement and comparing circuit 50 along input line 52.
Referring now to
The circuit 50 also is configured to receive a second summed current differential signal 68 from at least one, but often a plurality of, solid state switches configured parallel to the at least one solid state switch 14. The second summed current differential signal 68 represents current data from one or more solid state switches that are disposed within the power distribution system 10 and operate neither upstream nor downstream of the at least one solid state switch 14. As will be evident from the description below, it is desirable to bundle the information from all solid state switches in parallel, or at a single level, in order to transmit such information to at least one upstream solid state switch. The second summed current differential signal 68 passes through a second low pass filter 70 in order to damp noise, then subsequently through a second differential amplifier 72 that converts the second summed current differential signal 68 to a second single-ended signal 74. The second single-ended signal 74 is transmitted to a summing logic unit 76. The summing logic unit 76 also receives the current data from the current sensor 34. It is also conceivable that the summing logic unit 76 also receives current data from other sources, however, the function of the summing logic unit 76 will be readily apparent from description of simply the two sources. The summing logic unit 76 combines the signals into a summed current signal 80, thereby representing a summed signal comprising a variety of signals from solid state switches at the same level. The summed current signal 80 is then transmitted to an amplifier 82 for receiving the summed current signal 80 and converting to a summed current differential signal 84 that then passes through a third low pass filter 86. The summed current differential signal 84 may then be transmitted to another solid state switch, such as a solid state switch located upstream, as is the case with the previously discussed first summed current differential signal 56 into the circuit 50. Therefore, the circuit 50 is configured to receive a summed signal containing current data from downstream solid state switches, as well as transmit a summed signal containing current data to upstream solid state switches. In this way, the at least one solid state switch 14 receives information from downstream switches that permits the determination of whether a current “leak” is occurring and also provides information to upstream switches to make a similar determination.
A method of measuring and comparing current 90 of the power distribution system 10 is also provided. The power distribution system 10, and more particularly the current measurement and comparing circuit 50 have been previously described and specific structural components need not be described in further detail. The method 90 includes integrating a current sensor 92 within a control section, where the current sensor is in operable communication with at least one switch. Current data obtained by the current sensor is distributed to a switch control that controls the at least one solid state switch 94 and to the current measurement and comparison circuit via an input line 96. The circuit compares the current data received from the current sensor via the input line to a first summed current differential signal 98, as described above. The comparison provides a current difference and if the current difference exceeds a predetermined control magnitude, a fault logic circuit initiates at least one corrective action, such as switching off the at least one solid state switch or providing a message to a control system, which may comprise the microprocessor described above. In addition to the comparison aspect of the method 90, a summing of the current data 100 from the current sensor with other switches at the same level is provided. The summed signal may then be supplied 102 to one or more switches located upstream, where a similar comparison process may occur at the next level.
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
