Battery-powered wireless process variable transmitter

Abstract

This device provides a safe and efficient wireless process variable transmitter that uses energy from multiple primary cell batteries connected in parallel. [Solution] In a wireless process variable transmitter (field device), the battery power supply 46 includes a plurality of battery power banks 50A to 50C, each having primary cell batteries 52A to 52C; low-voltage cutoff circuits 54A to 54C, which are electrically connected to the primary cell batteries and provide an electrical connection to the primary cell batteries when the voltage of the primary cell batteries exceeds a threshold; and an ideal diode that has an input electrically connected to the primary cell batteries via the low-voltage cutoff and provides a power bank output. A power sharing node 62 has an input that is connected to the battery power bank output of each of the plurality of battery power banks and has a shared power output that supplies power to the circuit of the wireless process variable transmitter.

Description

Technical Field

[0001] The present invention relates to a type of process variable transmitter used to sense process variables in an industrial process. More specifically, the present invention relates to a battery-powered wireless process variable transmitter.

Background Art

[0002] In an industrial environment, control systems are used to monitor and control inventories such as industrial processes and chemical processes. Generally, a control system performs these functions using several field devices distributed at important locations of an industrial process. The field devices can operate in various different facilities. Examples of process facilities include oil, pharmaceuticals, chemicals, pulp, and other processing facilities. These field devices are communicably coupled to a control circuit in a control room.

[0003] Field devices are used by the process control measurement industry for various purposes. Usually, such devices have a ruggedized housing so that they can be installed outdoors in a relatively harsh environment and withstand extreme climates of temperature, humidity, vibration, and mechanical shock. Also, field devices usually operate at relatively low power. For example, several field devices that receive all of their operating power from a known 4 - 20 mA loop are currently available.

[0004] Conventionally, field devices have been coupled to a process communication system (such as a control room) by physical conductors. Such a wired connection has not only supplied power to the field device but also provided a path for communication. One limitation of wired field devices is that it can be laborious to install because the wiring has to be extended to each physical location of the field device.

[0005] More recently, field devices have emerged that use wireless communication to communicate with control rooms and / or other suitable devices. These wireless field devices are generally equipped with an internal power source, such as a battery, that can supply operating power to the wireless field device for several years.

[0006] The use of wireless technology in industrial process industries has created a need for a method of locally powering wireless transmitters. Batteries are one way to provide local power. However, one problem with batteries is their limited capacity. Generally, there is a trade-off between battery capacity and higher update speeds or higher loads resulting from longer transmitter life and / or network configurations. Therefore, it is desirable to power field devices so that larger capacity batteries can be used. [Overview of the project]

[0007] A wireless process variable transmitter for use in industrial processes includes a process variable sensor configured to sense process variables in an industrial process and supply a process variable sensor output. A measuring circuit coupled to the process variable sensor supplies an output related to the process variable sensor output. A wireless communication circuit coupled to the measuring circuit is configured to wirelessly transmit information related to the process variable sensor output to a remote location. The battery power supply includes multiple battery power banks, each having a primary cell battery, and a low-voltage cutoff circuit electrically connected to the primary cell batteries, providing an electrical connection to the primary cell batteries when the voltage of the primary cell batteries exceeds a threshold, and the primary cell batteries via the low-voltage cutoff. The power sharing node has an input that is electrically connected to an ideal diode that provides a power bank output. The power sharing node has an input that is connected to the respective battery power bank outputs of the multiple battery power banks and has a shared power output that supplies current from each primary cell battery in the multiple battery power banks. The power supply circuit is electrically connected to the shared power output, which is configured to power a measurement circuit and a wireless communication circuit using the power shared among each primary cell battery in the multiple power banks.

[0008] This summary is provided to introduce, in a simplified form, the selection of concepts that will be further explained in the detailed description below. This summary is not intended to identify any significant or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to any implementation that solves any or all of the defects described in the background art. [Brief explanation of the drawing]

[0009] [Figure 1] This diagram shows an industrial process including a wireless process variable transmitter. [Figure 2] Figure 1 is a simplified block diagram of the wireless process variable transmitter. [Figure 3] Figure 2 is a simplified block diagram of multiple power banks in a battery power supply. [Modes for carrying out the invention]

[0010] Embodiments of this disclosure are described in full below with reference to the accompanying drawings. Elements identified by the same or similar reference numerals refer to the same or similar elements. For the sake of simplicity, some elements may not be shown in each drawing. Various embodiments of this disclosure may be embodied in many different forms and should not be construed as being limited to the specific embodiments described herein. Rather, these embodiments are provided so as to make this disclosure thorough and complete and to fully convey the scope of this disclosure to those skilled in the art.

[0011] In the industrial process control industry, there is a growing demand for battery-powered industrial field devices, specifically process variable transmitters, to provide additional functionality at a faster update rate. Meeting this demand comes at the expense of shorter battery life and more frequent battery replacements by operators. While battery technology continues to improve, it is not keeping pace with industry needs. New power management solutions are needed to provide field devices that meet industry requirements.

[0012] As explained in the background technology section, there are several types of process variable transmitters that operate wirelessly. Such transmitters are desirable to include an internal power source, such as a battery. In some installations, primary cell batteries (non-rechargeable batteries) are more advantageous than secondary cell batteries (rechargeable batteries). These advantages include reduced costs and increased energy storage capacity. The more power available to a process variable transmitter, the greater the capabilities it can provide. This includes increased data calculation and diagnostics, increased output signal strength, and increased update speed.

[0013] One particularly promising primary cell battery is the lithium thionyl chloride primary cell battery due to its high energy storage capacity. Some primary cells are difficult to connect in parallel to obtain higher capacity. However, lithium thionyl chloride primary cells are particularly problematic when connected in parallel because the weaker battery in the parallel connection is charged by the other batteries. This results in an unstable operating state that can lead to thermal runaway.

[0014] The present invention includes an industrial wireless process variable transmitter having a power bank configuration including a primary cell battery configured for parallel connection. In one particular configuration, the power bank comprises a primary cell battery, a low-voltage cutoff circuit, an energy limiter, and an ideal diode, with a minimum of these being... It includes at least one. The circuit enables a safe and efficient means of using energy from multiple primary cell batteries connected in parallel.

[0015] Figure 1 is a simplified diagram of an industrial process 10 including a wireless process variable transmitter (field device) 12 configured to sense process variables of a process fluid in a process pipe 14 using a process variable sensor 16. However, the present invention is applicable to process variable transmitters that sense other types of process variables. The wireless process variable transmitter 12 communicates with a remote location 18 using a radio frequency signal communicated between a communication circuit (not shown in Figure 1) and antennas 20 and 22. During operation, the process variable transmitter 12 senses process variables of a process fluid in a pipe 14 using a process variable sensor 16. The process variable sensor 16 may be any type of process variable, examples of which include sensors for sensing pressure, flow rate, differential pressure, corrosion, gas concentration, level, temperature, pH, turbidity, location information, acoustic data, etc. The process variable transmitter 12 uses internal circuitry (not shown in Figure 1) to acquire measurement data related to the sensed process variables. Next, the process variable transmitter 12 communicates data related to the sensed process variables to the remote location 18 using a wireless connection between antennas 20 and 22. The communication may also include raw data, diagnostic information, other sensed process variables, environmental data, time information, and other information that identifies a specific process variable transmitter 12, such as an address. Furthermore, the remote location 18 may also communicate information to the process variable transmitter 12. Such communication may include, among other things, process variables sensed by other devices, commands, and programming instructions. The communication may take place, for example, directly or via an intermediate connection such as a mesh network.

[0016] Figure 2 is a simplified block diagram of a wireless process variable transmitter 12, including a measurement circuit 40 connected to a process variable sensor 16. The measurement circuit 40 is configured to perform initial processing on the sensor output from the process variable sensor 16 and supply the output to a controller 42. The controller 42 may include a digital controller, such as a microprocessor, and the measurement circuit 40 may include an analog-to-digital converter to supply a digital output related to the sensed process variable. The controller 42 controls a wireless communication circuit 44 to supply a wireless radio frequency output using an antenna 20 related to the sensed process variable. Exemplary process variable sensors 16 include a corrosion sensor configured to measure the corrosion rate of process components, a pressure sensor configured to measure the pressure of a process fluid, a temperature sensor configured to measure the temperature of an industrial process, an acoustic sensor to measure sound and vibration in an industrial process, a gas sensor to measure the concentration of a gas in an industrial process, a level sensor configured to measure the level of a process fluid contained in a tank, for example, a position tracking sensor configured to monitor the location of process components or personnel.

[0017] Figure 2 also shows a battery power supply 46, which includes multiple power banks 50 as shown in Figure 3. The battery power supply 46 supplies battery power output to a power supply circuit 48, which in turn powers the measurement circuit 40, the controller 42, and the wireless communication circuit 44. In some configurations, power is also supplied to operate the variable sensor 16.

[0018] Wireless communication via circuit 44 can be carried out according to any suitable communication technology. Many standards are used, including WirelessHART® (IEC62591) or ISA100.11a (IEC62734), or other wireless communication protocols such as WiFi, LoRa®, Sigfox, BLE, or any other suitable protocol, including custom or dedicated communication protocols.

[0019] Figure 3 shows a battery power supply 4 including multiple battery power banks 50A, 50B, and 50C. This is a simplified schematic diagram of 6. The configuration shown in Figure 3 provides a self-managing power distribution circuit that offers a means of extending the operating life of the field device 12 by using multiple batteries. The embodiment shows the use of three battery banks 50A, 50B and 50C. However, any number of banks may be used.

[0020] The use of lithium thionyl chloride primary cell batteries is desirable due to their high energy capacity. However, unlike typical battery technologies, lithium thionyl chloride primary cell batteries cannot be directly connected in parallel as a means of increasing capacity. When lithium thionyl chloride primary cell batteries are connected in parallel, the weaker battery in the group is charged by the other batteries. This can lead to unstable operating conditions and potentially cause thermal runaway. The configuration shown in Figure 3 allows for a safe and efficient means of using energy from multiple batteries.

[0021] According to this embodiment, the battery power supply 46 includes three separate battery power banks 50A, 50B, and 50C. In this configuration, each power bank is identical to one another. Each power bank includes primary cell batteries 52A, 52B, and 52C, which are connected to low-voltage cutoff circuits 54A, 54B, and 54C, respectively. The outputs from the low-voltage cutoffs are coupled to protection elements 56A, 56B, and 56C, respectively, which are connected to a series of ideal diodes. Each battery power bank 50A, 50B, and 50C preferably includes three ideal diodes, as shown in Figure 3 as 58A1, 2, 3, 58B1, 2, 3, and 58C1, 2, 3. The use of three diodes allows the unit to meet inherent safety requirements for redundancy. The ideal diodes can operate according to any ideal diode technology. In one particular embodiment, the ideal diodes comprise an active circuit.

[0022] The outputs from power banks 50A, B, and C function as a power sharing node and are coupled to a power sharing resistor 62 that supplies power to a power supply circuit 48 configured as a switching regulator. A bulk capacitor 64 operates to filter and smooth out any voltage fluctuations at the power sharing node 62.

[0023] The battery feedback outputs are supplied via resistors 60A, 60B, and 60C that are each coupled to the outputs from protection elements 56A, 56B, and 56C. The connections via resistors 60A, 60B, and 60C are coupled to the controller 42 and can be used to monitor the voltages of each battery 52A, 52B, and 52C respectively. Resistors 60A, B, C and 62 provide an inherent safety margin to prevent excessive power from batteries 52A, B, C from entering the device electronics.

[0024] Generally, each bank 50A - C is identical to each other. The outputs of each bank 50A - C are commuted at the power sharing resistor 62 to supply power to the device 12. The low voltage cut-off circuits 54A - 54C are used to disconnect batteries 52A - 52C from the circuit when batteries 52A - 52C are nearly depleted. This prevents batteries 52A - 52C from being completely exhausted and can be safely transported during recycling.

[0025] Protection elements 56A - 56C limit the total energy to the circuit to the energy ratings of the downstream components. Elements 56A - C, together with the power sharing resistor 62, make the circuit intrinsically safe for use in hazardous locations. The use of a triple redundant ideal diode circuit 58 is a feature of the design. The diodes 58 provide four main functions. Those diodes allow the battery discharge current to flow to the load. Further, those diodes block the reverse current from the charging of battery 52. Also, those diodes provide inherent safety and limit the voltage loss in each bank 50A - C. The maximum energy between the battery and the load Energy transfer occurs when the voltage losses in each bank are kept low. Using ideal diodes, the voltage losses are limited to less than 50 mV compared to a 1 volt drop when using conventional Schottky diodes. This can result in an improvement of more than 60% in battery life.

[0026] During normal operation, all three battery banks 50A, 50B, and 50C operate in concert with each other to supply current I L to the load. Initially, the load is powered only by the battery bank 50A - C with the highest voltage. As the voltage on that bank decays, the next closest voltage bank begins to share the load. Eventually, all three banks 50A - C supply current to the load. The voltage of each battery bank is periodically read by the controller 42 using battery feedback connections A - C. This allows the device 12 to report the health of each battery 52A - C to a remote location 18. A low battery warning can be issued to the operator so that depleted batteries can be replaced. For example, the controller 42 can issue a warning using a wireless communication circuit 44 transmitted to the remote location 18 indicating that one or more of the batteries 52A - C are at a low voltage and should be replaced. A local warning can also be provided by the I / O 70.

[0027] This self-managing power distribution circuit 46 offers several advantages over one that switches to one battery at a time when a battery is depleted. For example, batteries left unloaded for extended periods tend to form a passivation layer. This layer acts as a series resistance, preventing the battery from supplying load current and causing a prolonged drop in battery voltage when first used. This self-managing technique prevents passivation by continuously duty-cycle the load to each battery as part of its load-sharing concept. This concept is expandable by allowing the addition of any number of battery banks 50 to achieve the desired capacity. Even in a multi-bank system, fewer batteries can be installed to power the device as needed. This concept also allows for hot-swapping of batteries, as one or two other batteries continue to supply power to the load without interruption. Another advantage of this concept is the elimination of the complexity of having to decide when to replace an old battery and when to replace a new one. The self-managing switching between battery banks 50 provided by the present invention, along with continuous health monitoring, eliminates these problems.

[0028] In one embodiment, the transmitter 12 includes an additional input / output circuit 70 that can provide additional functionality. For example, the I / O circuit 70 can provide a local indicator, such as an LED, LCD, or other such interface device, to inform the user of the current status of each battery 52. ​​Another means of communicating this information is via a digital or analog communication connection to a remote location 18. The I / O 70 can also be used to supply information to the controller 42, such as an indication that one of the batteries 52 has been replaced. The I / O circuit 70 can be a manual local input and / or can bring local communication via Bluetooth® or WiFi, etc.

[0029] While the present invention has been described with reference to preferred embodiments, modifications in form and detail can be made without departing from the spirit and scope of the invention, as will be apparent to those skilled in the art.

[0030] The following are additional notes regarding this disclosure. (Additional note 1) In a wireless process variable transmitter for use in industrial processes, A process variable sensor configured to sense process variables in an industrial process and supply a process variable sensor output, A measurement circuit coupled to the process variable sensor and configured to supply an output related to the output of the process variable sensor, A wireless communication circuit coupled to the measurement circuit and configured to wirelessly transmit information related to the process variable sensor output to a remote location, A battery power supply equipped with multiple battery power banks, Equipped with, Each of the aforementioned battery power banks is Primary cell battery, A low-voltage cutoff circuit is electrically connected to the primary cell battery and provides an electrical connection to the primary cell battery when the voltage of the primary cell battery exceeds a threshold. An ideal diode having an input electrically connected to the primary cell battery via a low-voltage cutoff, which provides the output of the power bank, A power sharing node connected to the output of each of the plurality of battery power banks, having an input having a shared power output including current from at least one primary cell battery in the plurality of battery power banks, A power supply circuit electrically connected to the shared power output and configured to supply power to the measurement circuit and the wireless communication circuit using power from at least one primary cell battery in a plurality of power banks, A wireless process variable transmitter equipped with a wireless process variable transmitter. (Additional note 2) The wireless process variable transmitter according to Appendix 1, wherein each of the plurality of battery power banks includes an energy limiter that is electrically connected to the primary cell battery and configured to limit the amount of energy delivered by the primary cell battery. (Additional note 3) The wireless process variable transmitter according to Appendix 1, wherein the power supply circuit is powered by primary cell batteries in a plurality of power banks having the highest voltage level. (Additional note 4) Each of the multiple power banks includes at least three ideal diodes connected in series, thereby providing intrinsic safety, as described in Appendix 1, for the wireless process variable transmitter. (Additional note 5) The wireless process variable transmitter as described in Appendix 1, wherein the power sharing node is equipped with a resistor. (Additional note 6) The wireless process variable transmitter according to Appendix 1, wherein the process variable sensor comprises at least one of a pressure sensor, a flow sensor, a corrosion sensor, a gas concentration sensor, a level sensor, a temperature sensor, a pH sensor, a turbidity sensor, a position sensor, and an acoustic sensor. (Additional note 7) The wireless process variable transmitter according to Appendix 1, wherein the power supply circuit supplies power to the process variable sensor. (Additional note 8) A wireless process variable transmitter according to Appendix 1, comprising a plurality of battery readback connections, each coupled to one of the plurality of battery power banks, which are configured to supply a voltage related to the battery voltage from each power bank. (Additional note 9) A wireless process variable transmitter as described in Appendix 8, wherein the plurality of battery readback connections are coupled to the controller. (Additional note 10) A wireless process variable transmitter as described in Appendix 8, including an output supplied based on the voltage on a battery readback connection indicating low battery. (Additional note 11) A wireless process variable transmitter as described in Appendix 10, wherein the output is supplied remotely. (Additional note 12) A wireless process variable transmitter as described in Appendix 10, wherein the output is supplied locally. (Additional note 13) The wireless process variable transmitter as described in Appendix 8, wherein the plurality of battery readback connections include a series resistor. (Additional note 14) The wireless process variable transmitter as described in Appendix 13, wherein the series resistor provides an inherent safety boundary. (Additional note 15) The wireless process variable transmitter as described in Appendix 1, wherein the power sharing node provides an inherent safety boundary. (Additional note 16) The wireless process variable transmitter according to Appendix 1, wherein the power supply circuit includes a switching regulator. (Additional note 17) The wireless process variable transmitter according to Appendix 1, wherein one of the primary cell batteries in the plurality of battery power banks can be disconnected without interrupting the shared power output from the power sharing node. (Additional note 18) The ideal diodes in the plurality of battery power banks prevent current from flowing to the primary cell battery, as described in Appendix 1, for the wireless process variable transmitter. (Additional note 19) A wireless process variable transmitter as described in Appendix 1, including a bulk capacitor connected to the shared power output. (Additional note 20) The aforementioned plurality of battery power banks reduce the self-passivation of the primary cell battery, as described in Appendix 1, for the wireless process variable transmitter. (Additional note 21) The wireless process variable transmitter according to Appendix 1, wherein the primary cell battery includes a lithium thionyl chloride primary cell battery.

Claims

1. In a wireless process variable transmitter for use in industrial processes, A process variable sensor configured to sense process variables in an industrial process and supply a process variable sensor output, A measurement circuit coupled to the process variable sensor and configured to supply an output related to the output of the process variable sensor, A wireless communication circuit coupled to the measurement circuit and configured to wirelessly transmit information related to the process variable sensor output to a remote location, A battery power supply equipped with multiple battery power banks, Equipped with, Each of the aforementioned battery power banks is Primary cell battery, A low-voltage cutoff circuit is electrically connected to the primary cell battery and provides an electrical connection to the primary cell battery when the voltage of the primary cell battery exceeds a threshold. An ideal diode having an input electrically connected to the primary cell battery via a low-voltage cutoff, and providing an output to a power bank, comprising at least three ideal diodes connected in series, thereby providing intrinsic safety, A power sharing node connected to the output of each of the plurality of battery power banks, having an input having a shared power output that includes current from at least one primary cell battery in the plurality of battery power banks, A power supply circuit electrically connected to the shared power output and configured to supply power to the measurement circuit and the wireless communication circuit using power from at least one primary cell battery in a plurality of power banks, A wireless process variable transmitter equipped with a wireless process variable transmitter.

2. The wireless process variable transmitter according to claim 1, wherein each of the plurality of battery power banks includes an energy limiter that is electrically connected to the primary cell battery and configured to limit the amount of energy delivered by the primary cell battery.

3. The wireless process variable transmitter according to claim 1, wherein the power supply circuit is powered by primary cell batteries in a plurality of power banks having the highest voltage level.

4. The wireless process variable transmitter according to claim 1, wherein the power sharing node includes a resistor.

5. The wireless process variable transmitter according to claim 1, wherein the process variable sensor comprises at least one of a pressure sensor, a flow sensor, a corrosion sensor, a gas concentration sensor, a level sensor, a temperature sensor, a pH sensor, a turbidity sensor, a position sensor, and an acoustic sensor.

6. The wireless process variable transmitter according to claim 1, wherein the power supply circuit supplies power to the process variable sensor.

7. The wireless process variable transmitter according to claim 1, comprising a plurality of battery readback connections, each coupled to one of the plurality of battery power banks, which are configured to supply a voltage related to the battery voltage from each power bank.

8. The wireless process variable transmitter according to claim 7, wherein the plurality of battery readback connections are coupled to a controller.

9. A wireless process variable transmitter according to claim 7, comprising an output supplied based on a voltage on a battery readback connection indicating low battery.

10. The wireless process variable transmitter according to claim 9, wherein the output is supplied remotely.

11. The wireless process variable transmitter according to claim 9, wherein the output is supplied locally.

12. The wireless process variable transmitter according to claim 7, wherein the plurality of battery readback connections include a series resistor.

13. The wireless process variable transmitter according to claim 12, wherein the series resistor provides an inherent safety boundary.

14. The wireless process variable transmitter according to claim 1, wherein the power sharing node provides an inherent safety boundary.

15. The wireless process variable transmitter according to claim 1, wherein the power supply circuit comprises a switching regulator.

16. The wireless process variable transmitter according to claim 1, wherein one of the primary cell batteries in the plurality of battery power banks can be disconnected without interrupting the shared power output from the power sharing node.

17. The wireless process variable transmitter according to claim 1, wherein the ideal diodes in the plurality of battery power banks prevent current from flowing to the primary cell battery.

18. The wireless process variable transmitter according to claim 1, further comprising a bulk capacitor connected to the shared power output.

19. The wireless process variable transmitter according to claim 1, wherein the plurality of battery power banks reduce the self-passivation of the primary cell battery.

20. The wireless process variable transmitter according to claim 1, wherein the primary cell battery includes a lithium thionyl chloride primary cell battery.

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