CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority benefit of U.S. Provisional Application 62/010,076 filed June 10, 2014, the contents of which are hereby incorporated by reference.

TECHNICAL FIELD

[0002] The invention relates generally to input/output (I/O) systems for wide voltage ranges and having controlled power dissipation. In particular, the present invention relates to an isolated contact input module of an I/O system for controlling power dissipation.

BACKGROUND

[0003] In conventional I/O systems, a resistor loading technique for voltage inputs is typically used. Using this technique, as the input current increases, the input voltage increases. This results in an increase in power dissipation. Due to the input current increase, components must be incorporated into the I/O module to reduce or limit power dissipation. One example of such a component is a constant current device which in turn requires an appropriately sized heat sink. However, such a heat sink may cause the I/O module to substantially increase in size.

[0004] In other conventional I/O systems, dedicated circuitry with opto-couplers are implemented where an opto-light emitting diode (LED) is driven by a constant current regulator, which helps provide a steady light output even in the presence of voltage variations. This approach does not allow for measurement of voltage via the opto-LED or at other components such as a voltage controlled oscillator (VCO), and it may require that the current regulator include high-power components rated for high voltages.

SUMMARY

[0005] The various embodiments of the present disclosure are configured to provide an I/O system that includes an isolated contact input module for controlling an amount of operating current at a user system, thereby controlling power dissipation.

[0006] In one exemplary embodiment, the I/O system is provided. The I/O system includes an isolated contact input module connected to the user system. The input module includes a power control circuit that controls an amount of operating current at the user system, and an input decision unit that monitors the user system and transmits data corresponding to an operative state of the user system. The system also includes a control system isolated from the input module that receives the data, determines the amount of operating current and controls the power control unit. The power control circuit regulates power and current flow at the user system to reduce the need for large power dissipation devices.

[0007] In another exemplary embodiment, a method is provided that includes determining an amount of operating at the user system, and controlling, via a power control circuit of an isolated contact input module, the amount of operating current of the user system. The method also includes monitoring the user system and collecting data corresponding to an operative state of the user system, and receiving the data by a control system, determining the amount of operating current, and controlling the power control unit based on the determined amount of operating current.

[0008] The foregoing has broadly outlined some of the aspects and features of various embodiments, which should be construed to be merely illustrative of various potential applications of the disclosure. Other beneficial results can be obtained by applying the disclosed information in a different manner or by combining various aspects of the disclosed

embodiments. Accordingly, other aspects and a more comprehensive understanding may be obtained by referring to the detailed description of the exemplary embodiments taken in conjunction with the accompanying drawings in addition to the scope defined by the claims.

DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a block diagram illustrating an exemplary I/O system that can be implemented within one or more embodiments of the present invention.

[0010] FIG. 2 is a circuit schematic of the I/O system and the power control circuit thereof as shown in FIG. 1 that can be implemented within one or more embodiments of the present invention.

[0011] FIG. 3 is a flow diagram illustrating an exemplary method of implementing an embodiment of the present invention.

[0012] FIG. 4 is an illustration of an operation of the exemplary I/O system shown in FIG. 1 that can be implemented within one or more embodiments of the present invention. [0013] The drawings are only for purposes of illustrating preferred embodiments and are not to be construed as limiting the disclosure. Given the following enabling a description of the drawings, the novel aspects of the present disclosure should become evident to a person of ordinary skill in the art. This detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description are used to refer to like or similar parts of embodiments of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014] As required, detailed embodiments are disclosed herein. It must be understood that the disclosed embodiments are merely exemplary of various and alternative forms. As used herein, the word "exemplary" is used expansively to refer to embodiments that serve as illustrations, specimens, models, or patterns In other instances, well-known components, systems, materials, or methods that are known to those having ordinary skill in the art have not been described in detail in order to avoid obscuring the present disclosure. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art.

[0015] Exemplary embodiments of the present invention provides a method and an I/O system having an isolated contact input module for controlling an operating current at a user system. Specifically, the I O system is capable of controlling a current flowing into the user system at the input terminals thereof which is hereinafter referred to as "a wetting current." The wetting current is controlled over a wide voltage range, for example, the range may be from about 12 Volts (V) to about 400 V. Consequently, a lower operating power may be used, and this eliminates the need for additional heat sink assemblies or other heat dissipation devices for dissipating heat from components thereof. Further, since the I O system does not require large circuitry, cost is minimized.

[0016] FIG. 1 is a block diagram illustrating an exemplary I/O system that can be implemented within one or more embodiments of the present invention. The I/O system 100 includes an isolated contact input module 110 and a backplane 120. The isolated contact input module 1 10 is connected to an external user system 130, and a control system 140 via the backplane 120.

[0017] The isolated contact input module 110 includes a power control circuit 1 12, an input decision unit 1 14 and a terminal block 116. The isolated contact input module 110 can be any type of electronic circuit board or circuitry that includes connections to support the power control circuit 1 12 and the terminal block 116. Alternatively, the circuitry can be placed within an application-specific integrated circuit (ASIC) similar to the ASIC disclosed in U.S.

Application Serial No. 13/864,539 cited herein. In other embodiments, the circuitry may be implemented using discrete components placed on a circuit board.

[0018] The power control circuit 1 12 can include electrical circuitry which regulates input current (i.e., wetting current) at the user system 130 supplied thereto via the terminal block 116 connected between the power control circuit 1 12 and the user system 130. Additional details regarding the power control circuit 1 12 will be discussed below in reference to FIG. 2.

[0019] The input decision unit 114 monitors operations of the user system 130 and transmits data corresponding to the operation state of the user system 130 to the control system 140 via the terminal block 1 16 and the backplane 120 connected to the control system 140. According to an embodiment, the input decision unit 1 14 determines an open/close state of a plurality of switches of the user system 130. The data obtained is transferred to the control system 140 at predetermined time intervals.

[0020] The input decision unit 1 14 may determine the state of the plurality of switches of the user system 130, and the power control circuit 1 12 may regulate the wetting current similar to the functions of the contact input apparatus disclosed in Application Serial No. 13/864,539 by Dan Alley, entitled "Programmable Contact Input Apparatus and Method of Operating the Same" filed on April 16, 2013, the contents of which are incorporated herein in its entirety by reference.

[0021] The terminal block 116 is electrically coupled with the power control circuit 112 and the user system 130. The terminal block 116 includes terminals for receiving connection wires for connecting to the user system 130 and electrical ground and shield connections. In some embodiments, the shield connections can connect to the backplane 120, to a wall or to another device instead of to the electrical ground. The I/O system 100 can be used with different types of signals and flow directions to connect to the user system 130 via a programming application.

[0022] The backplane 120 includes a plurality of connectors that allow electronic modules to be connected thereto. The backplane 120 is connected to and supports the isolated contact input module 1 10 and the control system 140 via an input function thereof. The backplane 120 can supports any power supply and analog or digital input module or output module or any other connections. In the present invention, the backplane 120 can include any number of connectors and support any desired connections as necessary.

[0023] The control system 140 monitors the power control circuit 112 and any other devices of the I/O system 100 such as sensors, measurement devices, or other circuitry (not shown). The control system 140 also determines and controls the amount of power of the I/O system 100. The control system 140 can be any combination of hardware components and software modules capable of controlling any other hardware components or software modules. Examples control systems include the use of Ethernet connected modules each containing a processor to provide the switch input states using protocols for real-time communications such as Profinet, or the use of modules connected on a mechanical backplane sharing a processor interface and power supply such as a programmable automation controller (e.g., GE Rx3i programmable logic control system).

[0024] The user system 130 can include any power-operated system, for example, an automobile or other vehicle system or any type of communication system. The user system 130 includes a number of switches that are monitored and/or controlled by the control system 140. The isolated contact input module 110 is connected to the user system 130 via the terminal block 116, and the input decision unit 114 determines if the voltage at the terminal block 1 16 is above or below a threshold voltage. Any system of the present invention that requires a wide range of user supplied voltages across terminal block connections for use by a decision unit is required to account for resulting power dissipation. Therefore, some example systems which may be implemented with the present invention include but are not limited to programmable logic devices, power line monitoring devices, or dedicated controls such as found on heating and ventilation air conditioning (HVAC) systems. Embodiments of the present invention provide for the wide variation in voltages while preventing commissioning failures due to incorrect wiring (e.g. connecting 240 V to a 24 volt input with 100 times the dissipation for a resistive load and 10 times the dissipation for a constant power load within the device. The present invention keeps the power dissipation bounded and relatively constant, allowing for the input decision unit 1 14 to report that the voltage was sensed but is not the correct range.

[0025] Based on current and voltage requirements of the user system 130, a user selects an appropriate isolated contact input module 110 for the I/O system 100. The control system 140 instructs the isolated contact input module 110 of the amount of current the user system 130 can draw under a normal operation thereof. The input module 110 according to embodiments of the present invention, is cable of sensing from approximately 5 Volts (V) to 240 Volts (V). The present invention alters the current based on the amount of voltage to maintain a limit of the dissipated power.

[0026] Upon powering on the user system 130, the power control circuit 112 allows a controlled amount of current to flow to user system 130 based on the instructions received from the control system 140. As the voltage increases at the terminal block 1 16, the current decreases until reaching a current threshold. While the current is regulated, power being sent to user system 130 is also controlled. Also, the input decision unit 114 monitors and transmits data corresponding to operating conditions of user system 130 to the control system 140, for reporting purposes to other external devices and/or systems monitoring the user system 130.

[0027] The operation of the isolated contact input module 100 will now be discussed in greater detail below in reference to FIG. 2. FIG. 2 is a circuit schematic of an I/O system 100 and the power control circuit 1 12 of the isolated input contact module 110 thereof depicted in FIG. 1.

[0028] The power control circuit 1 12 includes a local supply 210, a source voltage 212, a resistor 214, a current regulator 216 (e.g., a transistor) including a source resistor 218, a feedback device 220 (e.g., a transistor), a voltage divider 222 comprising a pair of resistors 223 and 224, a feedback voltage 226 (i.e. sensed voltage V _sense ) and a zener clamp diode 230.

[0029] The local supply 210 can be a voltage source such as a planar transformer powered from the control system 140 (depicted in FIG. 1). Alternatively, in other embodiments, the local supply 210 can include a zener diode biased via a resistor and using a voltage at the terminal block 116 (depicted in FIG. 1). The local supply 210 supplies a fixed gate voltage to the current regulator 216.

[0030] The source resistor 218 of the current regulator 216 is connected in series with the feedback device 220. The feedback device 220 provides feedback from the source voltage 212. The current regulator 216 and the feedback device 220 can be any type of transistor such as field effect transistors (FETs), negative channel field effect transistors (NFET), bipolar junction transistors (B JTs), insulated-gate bipolar transistors (IGBT), and or any other type of suitable device.

[0031] The voltage divider 222 reduces voltage at the zener clamp diode 230. The resistance of voltage divider 222 can be selected during the product design based on a desired reduction in current. The feedback voltage 226 controls the base voltage at the feedback device 220 and thus the emitter voltage by a base-emitter diode voltage drop, thereby adjusting the voltage across the source resistor 218 to provide a higher wetting current at lower voltages while the wetting current decreases to a low fixed amount at high voltages.

[0032] The zener clamp diode 230 is a diode that allows the feedback voltage 226 to increase up to a fixed value as current flows through the diode 230. Once the fixed value is met, current will increase through the diode 230 while the diode voltage remains relatively constant. The zener clamp diode 230 limits the amount of feedback voltage 226 such that the source voltage at the current regulator 216 (i.e., the current source transistor 216) is not too high to turn off the current source transistor 216 by having the drain voltage kept lower than the gate voltage from local supply 210. Referring back to Fig. 1, a user may vary the current for a given operating voltage and the control system 140, then transfer corresponding data to the isolated contact input module 1 10. The local supply 210 and current regulator 216 of Fig. 2, are then adjusted by adjusting the gate voltage with the current increasing as the gate voltage increases. According to this embodiment, the local supply 210 may be based on a digital to analog converter or other circuitry changing the operating setting information to a voltage.

[0033] Based on the user system requirements, the resistor 214 is provided to allow for a maximum current in the event of a component failure such as in a case of a short of the current regulator 216. During operation of the I/O system 100, as the source voltage 212 increases, feedback to the base of the feedback device 220 increases the base voltage which in turn increases the voltage at the emitter of the feedback device 220. Because the gate to the current regulator 216 remains at the same voltage, a voltage drop across the source resistor 218 occurs, thus resulting in a decrease in current.

[0034] Next, the current being drawn by the current regulator 216 drops to a threshold amount. Upon reaching the threshold amount, the zener clamp diode 230 locks or clamps the base of the feedback device 220 to a fixed maximum value, allowing the current through the current regulator 216 to remain at a lower fixed value compared to the value possible at low input voltages.

[0035] In the case of the resistance through the voltage divider 222 increasing, the voltage at the emitter of feedback device 220 when therefore approach the voltage at the gate of current regulator 216 and thus would result in zero current flow. Consequently, the zener clamp diode 230 continues to maintain a base current even when there is a high voltage. The values of the resistors 223 and 224 and the zener clamp diode 230 are selected to adjust the rate of decrease in current as the input rises and provide a flat current above the set voltage. It will be appreciated that the various examples described herein use various components (e.g., resistors) that have certain values and these values may be varied as necessary.

[0036] FIG. 3 is a flow diagram illustrating an exemplary method 300 of implementing an embodiment of the present invention. The method 300 begins at operation 310 where an amount of operating current of the user system is determined and controlled upon powering on the user system 130 via a control system 140 controlling a power control unit 1 12. The process continues to operation 320 where when the voltage at the input increases, the current is regulated to decrease until reaching a threshold amount, and power sent to the user system 130 is controlled. In operation 330, the user system 130 is monitored and data corresponding to an operative state of the user system 130 is collected by the input decision unit 1 14 and sent to the control system 140, to determining the amount of operating current and control the power control unit based on the determination. According to another embodiment of the present invention, at operation 310, a user may vary the current for a given operating voltage and the control system 140 transfers corresponding data to the isolated contact input module 110. Then at operation 320, the local supply 210 and current regulator 216 are adjusted by adjusting the gate voltage with the current increasing as the gate voltage increases. FIG. 4 is an illustration 400 of an operation of the exemplary I/O system shown in FIG. 1 that can be implemented within one or more

embodiments of the present invention. The illustration depicts operating conditions of the user system 130 over a wide voltage range.

[0037] The illustration 400 includes a terminal input voltage measurement at line 402, an input power measurement at line 404, an input voltage measurement at line 406, and a current measurement at line 408. The circuit simulation used to generate the illustrated voltages has a slow ramp at start up from approximately 0 to 2 milliseconds (ms) followed by a rapid ramp from approximately 2 to 10 ms. Thus, in this illustration 400, the voltage was initially slowly increased.

[0038] Consequently, as the voltage is increased, for example, to above approximately 300V, the current measurement at 408 initially rises as the current regulator 216 turns on before dropping to a lower value due to engagement of feedback device 220 fed by zener clamp diode 230. Thus, the current remains at a low level for example, 1mA to maintain a minimal wetting current. This peak in the current occurs at lower voltages when the current begins to flow through current regulator 216 and the feedback device 220 is turned on, with the resulting low power consumption.

[0039] As voltage increases to a low threshold value, the feedback device 220 is engaged and controls behavior of the current regulator 216. Eventually, the voltage is no longer increased as the zener clamp diode 230 clamps the base voltage, thus resulting in a stable current measurement 408.

[0040] The input power measurement at line 404 ramps upwards and stabilizes as current at line 408 is configured to be a constant value. After a constant current measurement at 408 is achieved, further increases in voltage at line 402 cause reductions in current at line 408 such that a reducing slope in power occurs because the feedback device 220 increases voltage based on the voltage drop across the base thereof, thereby maintaining the power lower than if there were no feedback via the feedback device 220.

[0041] The voltage across source resistor 218 is utilized because the gate of current regulator 216 is across a constant voltage and accordingly the drain of the current regulator 216 is at a constant voltage. Because less voltage is flowing across source resistor 218, less current is also flowing, resulting in a lower current value. As mentioned above, zener clamp diode 230 eliminates the possibility of the current reaching a zero value. Once the zener clamp diode 230 clamp voltage is reached, the current at 408 remains at a lower constant value allowing power at 404 to increase. However, since the clamp occurs near the maximum voltage allowed on the isolated contact input module 1 10, overall power across all voltage levels remains low.

[0042] Embodiments of the present invention controls power dissipation based on the nonlinear current change over voltage while input current at low voltages remains high enough for wetting purposes. This provides an advantage of more compact packaging of input modules and the elimination of the use of heat sinks. In the exemplary embodiments, the current regulator 216 may be mounted directly to the circuit board using surface-mount components. Further, the cost of adding the additional power control unit is minimal compared to the assembly costs on the circuit board. In addition, cabinet heating is decreased, thereby increasing system reliability and decreasing cabinet cooling costs.

[0043] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.