String instrumentation module

Abstract

A monitoring system includes analog-to-digital converters that are isolated from each other and a microcontroller with digital isolation barriers. CAN identifiers (IDs) are hardwired into a harness so that units can be swapped without any reprogramming. Channels are configured to create significant voltage shifts when a voltage sensing wire in a harness is loose or disconnected, and the system responds to such voltage shifts as a fault. Each fuel cell voltage input channel is set up to precisely and accurately measure voltages of plus and minus 250 VDC; however, the fuel cell voltage input channels are tolerant to voltages up to 1500 VDC without damage.

Description

STRING INSTRUMENTATION MODULEBACKGROUNDTechnical Field

[0001] The present disclosure relates to systems and methods for monitoring a string of devices, and more particularly to systems and methods for monitoring strings of fuel cell stacks.Description of the Related Art

[0002] Conventional systems used to monitor strings of fuel cell stack use multiple voltage monitors to measure each of the fuel cell stacks, and produce an output signal provided to associated controller analog cards, which involves running multiple high voltage lines to a separate control room. Also, conventional systems used to monitor strings of fuel cell stacks require additional cables and analog cards for other string instruments (e.g., temperature sensors). For example, such systems constituted half of 200 required input / output (IO) measurements including associated cables and IO cards. Notably, conventional systems used to monitor strings of fuel cells do not deal with the issue of loose connections on a cell stack used for voltage measurements.

[0003] In addition, conventional systems used to monitor strings of fuel cells can be extremely complicated to install and maintain. Additionally, conventional systems used to monitor strings of fuel cells do not have the ability to detect extremely small changes in voltage, which are required to determine if there is a problem with the strings of fuel cell stacks or the systems used to monitor the strings of fuel cell stacks. Moreover, for some applications, there is no off-the-shelf device or system available.BRIEF SUMMARY

[0004] Embodiments of the present disclosure provide a reliable remotely mounted system that can interface with devices on a fuel cell string and communicate corresponding data to a central controller. Such devices include, but are not limited to, voltage measurement devices of fuel cell stacks, temperature sensors, and pressure sensors. Advantageously, measurements are compatible with a floating fuel cell system with multiple stacks, which are tolerant to voltages up to 1500 Volts Direct Current (VDC) with respect to pole-to-pole and pole-to-chassis conditions. In addition, embodiments of the present disclosure enable a central controller todetect loose connections between a monitoring system and a fuel cell string, and take an appropriate action.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0005] Non-limiting and non-exhaustive embodiments are described with reference to the following drawings. In the drawings, like reference numerals refer to like parts throughout the various figures unless otherwise specified.

[0006] For a better understanding of the present disclosure, reference will be made to the following Detailed Description, which is to be read in association with the accompanying drawings.

[0007] Figure 1 is a diagram of an operational system in accordance with embodiments described herein.

[0008] Figure 2A is a diagram of a monitoring system in accordance with embodiments described herein.

[0009] Figure 2B is a diagram of a stack voltage measurement module of the monitoring system shown in Figure 2A.

[0010] Figure 2C is a diagram of another stack voltage measurement module of the monitoring system shown in Figure 2A.DETAILED DESCRIPTION

[0011] According to the present disclosure, a monitoring system includes analog-to- digital converters that are isolated from each other and a microcontroller with digital isolation barriers. The analog-to-digital converters communicate with the microcontroller with a built in serial to peripheral interface (SPI). Power to the system may be converted with parallel redundant circuits and provided to the microcontroller with isolated DC / DC converters. Data is collected by the microcontroller and communicated to a central controller with an isolated bus interface. For example, the bus interface is a Controller Area Network (CAN) bus according to the CAN 2.0 specification. Advantageously, CAN identifiers (IDs) are hardwired into a harness so that units can be swapped without any reprogramming. Also advantageously, input voltage attenuators have different impedances for even and odd channels, so that if a voltage sensing wire were to come loose, a measured voltage shifts significantly and, in response, the central controller triggers a fault condition. According to one or more implementations, each fuel cell voltage input channel is set up to precisely and accurately measure voltages of plus and minus250 VDC of a fuel cell stack; however, the fuel cell voltage input channels are tolerant to voltages up to 1500 VDC without damage.

[0012] Figure 1 is a diagram of an operational system 100 in accordance with embodiments described herein. The operational system 100 includes a string of fuel cell stacks 102 coupled to a fuel cell controller 104. The string of fuel cell stacks 102 includes a fuel cell stack 106, a fuel cell stack 108, a fuel cell stack 110, a fuel cell stack 112, a fuel cell stack 114, and a fuel cell stack 116. Although not illustrated, each of the fuel cell stacks 106, 108, 110, 112, 114, and 116 includes a number of fuel cells. For example, each of the fuel cell stacks 106, 108, 110, 112, 114, and 116 includes 220 fuel cells. Strings of fuel cell stacks that include a larger or smaller number of fuel cell stacks are within the scope of the present disclosure. Also, fuel cell stacks that include a larger or smaller number of fuel cells are within the scope of the present disclosure.

[0013] The string of fuel cell stacks 102 and the fuel cell controller 104 are electrically coupled to a monitoring system 200 by a plurality of wires 118, 120, 122, 124, 126, 128, 130, 132, and 134, which form wiring harnesses.

[0014] A voltage VT1 on a first side of the fuel cell stack 106 is provided to the monitoring system 200 via the wire 118. A voltage VT2 on a second side of the fuel cell stack 106 and a first side of the fuel cell stack 108 is provided to the monitoring system 200 via the wire 120. A voltage VT3 on a second side of the fuel cell stack 108 and a first side of the fuel cell stack 110 is provided to the monitoring system 200 via the wire 122. A voltage VT4 on a second side of the fuel cell stack 110 and a first side of the fuel cell stack 112 is provided to the monitoring system 200 via the wire 124. A voltage VT5 on a second side of the fuel cell stack 112 and a first side of the fuel cell stack 114 is provided to the monitoring system 200 via the wire 126. A voltage VT6 on a second side of the fuel cell stack 114 and a first side of the fuel cell stack 116 is provided to the monitoring system 200 via the wire 128. A voltage VT7 on a second side of the fuel cell stack 116 is provided to the monitoring system 200 via the wire 130. A similar arrangement would be provided if there are more or fewer fuel cell stacks in the string to be monitored.

[0015] A first end of the wires 132 and 134 are electrically coupled to a fuel cell controller 104 and a second end of the wires 132 and 134 are electrically coupled to a network interface 136. In one or more implementations, the network interface 136 is a CAN serial bus interface mounted on a circuit board from which multiple pairs of pins extend, wherein each pair of pins can be electrically coupled together with a jumper. The CAN bus interface uses anaddress that is based on the pins. For example, if there are four pairs of pins, and only the first pair of pins is coupled together with a jumper, the CAN bus interface uses an address corresponding to “0001” binary when communicating with the monitoring system 200.

[0016] The monitoring system 200 may use the wires 132 and 134 to transmit a control signal to the fuel cell controller 104. If the monitoring system 200 detects an anomalous condition, the monitoring system 200 transmits a control signal to the fuel cell controller 104 that causes the fuel cell controller 104 to stop operation of the string of fuel cell stacks 102. For example, if the monitoring system 200 determines that one or more of the wires 118, 120, 122, 124, 126, 128, and 130 is loose (e.g., no longer connected to one of the string of fuel cell stacks 102), the monitoring system 200 transmits a control signal to the fuel cell controller 104 that causes the fuel cell controller 104 to stop operation of the string of fuel cell stacks 102.

[0017] Figure 2A is a diagram of a monitoring system 200 in accordance with embodiments described herein. As described in detail below with reference to Figures 2B and 2C, the monitoring system 200 includes a controller 202 that is electrically coupled to a stack voltage measurement device 204 and a stack voltage measurement device 206. The controller 202 includes a processor 202a and a memory 202b storing in processor-readable instructions that, when executed by the processor 202a, causes the controller 202 to perform the acts described herein. In one or more implementations, the controller 202 is a controller model number DSPIC33EV32GM104-E / P8 from Microchip Technology Inc. Other devices can be used to implement the controller 202 within the scope of the present disclosure.

[0018] The controller 202 communicates with the stack voltage measurement device 204 and the stack voltage measurement device 206, for example using the Serial Peripheral Interface (SPI) standard. The controller 202 generates a clock signal SCLK that is provided to devices in the stack voltage measurement device 204 and the stack voltage measurement device 206. The controller 202 also generates a Main Out, Sub In (MOSI) signal used to transmit data to devices in the stack voltage measurement device 204 and the stack voltage measurement device 206. Additionally, the controller 202 generates chip select (CS) signals CS_1, CS_2, CS_3, CS_4, CS_5, and CS_6, which are provided to respective devices in the stack voltage measurement device 204 and the stack voltage measurement device 206. In addition, the controller 202 receives a Main In, Sub Out (MISO) signal that is generated by devices in the stack voltage measurement device 204 and the stack voltage measurement device 206.

[0019] Using the various SPI signals, the controller 202 is able to control various devices to obtain data used to perform processing to determine whether there is an anomalous conditionin the string of fuel cell stacks 102, and / or connections between the string of fuel cell stacks 102 and the monitoring system 200. For example, the controller 202 uses the various SPI signals to request a particular analog-to-digital converter device to provide a digital value corresponding to a difference between two analog voltages at two particular input channel terminals and to receive the digital value from the particular analog-to-digital converter device.

[0020] Figure 2B is a diagram of a stack voltage measurement module 204 of the monitoring system 200 shown in Figure 2A. The stack voltage measurement module 204 receives the voltages VT1 through VT4 via the respective wires 118 through 124 (shown only in Figure 1) and respective connector terminals of a connector CN200.

[0021] The voltage VT1 is provided to a first input channel terminal of an analog-to- digital (A / D) converter device U201 via a group of resistors R200, R201, R203, and R204, which are electrically connected in series. This group comprises four resistors in this example, but more or fewer may be used. Similarly, in the description that follows, the resistors between VT2, VT3, VT4 etc. and the corresponding A / D converter devices U201, U204, U207 etc., may include more or fewer than the four resistors illustrated. A resistor R205 is electrically coupled between the first input channel terminal of the A / D converter device U201 and a second input channel terminal of the A / D converter device U201. That is, a first terminal of the resistor R205 is electrically coupled to the first input channel terminal of the A / D converter device U201 and the second input channel terminal of the A / D converter device U201. The voltage VT2 is provided to the second input channel terminal of the A / D converter device U201 via a second group of resistors R206, R207, R209, and R210, which are electrically connected in series.

[0022] A third input channel terminal of the A / D converter device U201 and a fourth input channel terminal of the A / D converter device U201 are electrically connected to a ground terminal of the A / D converter device U201, which is electrically coupled to ground terminals on a first side of a digital isolator device U200.

[0023] A capacitor C206 is electrically coupled between the first input channel terminal of the A / D converter device U201 and a ground potential GND l, which is at the same potential as the ground terminal of the A / D converter device U201. A capacitor C207 is electrically coupled between the first input channel terminal of the A / D converter device U201 and the second input channel terminal of the A / D converter device U201. A capacitor C208 is electrically coupled between the second input channel terminal of the A / D converter device U201 and the ground terminal of the second channel of the A / D converter device U201.

[0024] Notably, a resistor R202 is electrically coupled between the second input channel terminal of the A / D converter device U201 and a power supply terminal of the A / D converter device U201 through which the A / D converter device U201 receives power to operate. In addition, a resistor R208 is electrically coupled between the second input channel terminal of the A / D converter device U201 and the ground terminal of the A / D converter device U201. The resistors R202 and R208 are bias resistors that bias the voltage input to the second input channel terminal of the A / D converter device U201 halfway between the voltage at the power supply terminal of the A / D converter device U201 and the voltage at the ground terminal of the A / D converter device U201, which advantageously provides a great deal of fault tolerance.

[0025] More particularly, the A / D converter device U201 performs a differential measurement based on the voltages provided to the first input channel terminal and the second input channel terminal. Thus, a positive or a negative voltage gets applied to the first input channel terminal and the second input channel terminal. In order for the A / D converter device U201 to not be damaged, that voltage needs to be in a predetermined range with respect to the voltage provided to the ground terminal of the A / D converter device U201, for example, 0 to 5 V. This does not provide the ability to measure a positive and negative signal, which is desirable. The stack of fuel cells 102 is electrically floating and the A / D converter device U201 also is floating, because they do not have a ground reference to a chassis.

[0026] Accordingly, the resistors R202 and R208 are used to provide a bias to the second input channel terminal that is half-way between the voltage at the ground terminal of the A / D converter device U201 (e.g., 0 V) and power supply voltage provided to the A / D converter device U201 (e.g., 5 V). Thus, the resistors R202 and R208 bias the second input channel terminal of the A / D converter device U201 to 2.5 volts. Accordingly, the first input channel terminal of the A / D converter device U201 can now move up and down 2.5 V without damaging the A / D converter device U201. As a result, positive and negative voltages can be measured in a balanced way, e.g. in the full range plus or minus 2.5 V. If each of the fuel cell stacks 106, 108, 110, 112, 114, and 116 is designed to produce 250 V, the resistors R201, R201, R203, R204, R206, R207, R209, and R210 are selected to reduce voltage provided to the A / D converter device U201 to less than 5 V. If the wires 118 and 120 are incorrectly connected across all six of the fuel cell stacks 106, 108, 110, 112, 114, and 116, the voltage suppled via the connector 200 would be 1,500 V, which would usually damage the A / D converter device U201. However, due to the arrangement of the resistors R202 and R208, the voltage at the first and second inputterminals of the A / D converter device U201 stays within a range 0 to 5 V, and the A / D converter device U201 is not damaged even if the stacks are incorrectly connected.

[0027] A capacitor C200, a capacitor C201, and a capacitor C202 are electrically connected in parallel between the power supply terminal of the A / D converter device U201 and the ground potential GND l, which is at the same potential as the ground terminal of the A / D converter device U201. The power supply terminal of the A / D converter device U201 is electrically coupled to an isolated supply voltage terminal of a digital isolator device U200, which is electrically coupled to a selection terminal of the digital isolator device U200. An output channel A terminal of the digital isolator device U200 is electrically coupled to a serial clock input terminal of the A / D converter device U201. An output channel B terminal of the digital isolator device U200 is electrically coupled to a serial data input terminal of the A / D converter device U201. An output channel C terminal of the digital isolator device U200 is electrically coupled to a chip select terminal of the A / D converter device U201.

[0028] A capacitor C203, a capacitor C204, and a capacitor C205 are electrically coupled in parallel between a supply voltage terminal of the digital isolator device U200, which is electrically coupled to a supply voltage (e.g., 5 V), and a ground potential GND O that is provided to ground terminals of the digital isolator device U200 on a second side of the digital isolator device U200. It is noted that the ground potential GND O that is provided to ground terminals of the digital isolator device U200 on the second side of the digital isolator device U200 is different from the ground potential GND l that is provided to ground terminals of the digital isolator device U200 on the first side of the digital isolator device U200.

[0029] An input channel A terminal of the digital isolator device U200 is electrically coupled to a signal line for the SCLK signal. An input channel B terminal of the digital isolator device U200 is electrically coupled to a signal line for the MOSI signal. An input channel C terminal of the digital isolator device U200 is electrically coupled to a signal line for the CSI l signal. Also, the input channel C terminal of the digital isolator device U200 is electrically coupled to a first input terminal of a buffer device U202.

[0030] An output channel D terminal of the digital isolator device U200 is electrically coupled to a second input terminal of the buffer device U202. A ground terminal of the buffer device U202 is electrically coupled to the ground potential GND O that is provided to the ground terminals of the second side of the digital isolator device U200. An output terminal of the buffer device U202 is coupled to a signal line for the MISO signal.

[0031] The voltage VT2 is also provided to a first input channel terminal of an A / D converter device U204 via resistors R211, R212, R214, and R215, which are electrically connected in series. A resistor R216 is electrically coupled between the first input channel terminal of the A / D converter device U204 and a second input channel terminal of the A / D converter device U204. The voltage VT3 is provided to the second input channel terminal of the A / D converter device U204 via resistors R217, R218, R220, and R221, which are electrically connected in series.

[0032] A third input channel terminal of the A / D converter device U204 and a fourth input channel terminal of the A / D converter device U204 are electrically connected to a ground terminal of the A / D converter device U204, which is electrically coupled to ground terminals on a first side of a digital isolator device U203.

[0033] A capacitor C215 is electrically coupled between the first input channel terminal of the A / D converter device U204 and a ground potential GND 2, which is at the same potential as the ground terminal of the A / D converter device U204. A capacitor C216 is electrically coupled between the first input channel terminal of the A / D converter device U204 and the second input channel terminal of the A / D converter device U204. A capacitor C217 is electrically coupled between the second input channel terminal of the A / D converter device U204 and the ground terminal of the second channel of the A / D converter device U204.

[0034] Notably, a resistor R213 is electrically coupled between the second input channel terminal of the A / D converter device U204 and a power supply terminal of the A / D converter device U204 through which the A / D converter device U204 receives power to operate. In addition, a resistor R219 is electrically coupled between the second input channel terminal of the A / D converter device U204 and the ground terminal of the A / D converter device U204. The resistors R213 and R219 are bias resistors that bias the voltage input to the second input channel terminal of the A / D converter device U204 halfway between the voltage at the power supply terminal of the A / D converter device U204 and the voltage at the ground terminal of the A / D converter device U204, which advantageously provides a great deal of fault tolerance.

[0035] A capacitor C209, a capacitor C210, and a capacitor C211 are electrically connected in parallel between the power supply terminal of the A / D converter device U204 and the ground potential GND 2, which is at the same potential as the ground terminal of the A / D converter device U204. The power supply terminal of the A / D converter device U204 is electrically coupled to an isolated supply voltage terminal of a digital isolator device U203, which is electrically coupled to a selection terminal of the digital isolator device U203. Anoutput channel A terminal of the digital isolator device U203 is electrically coupled to a serial clock input terminal of the A / D converter device U204. An output channel B terminal of the digital isolator device U203 is electrically coupled to a serial data input terminal of the A / D converter device U204. An output channel C terminal of the digital isolator device U203 is electrically coupled to a chip select terminal of the A / D converter device U204.

[0036] A capacitor C212, a capacitor C213, and a capacitor C214 are electrically coupled in parallel between a supply voltage terminal of the digital isolator device U203, which is electrically coupled to a supply voltage (e.g., 5 V), and the ground potential GND O that is provided to ground terminals of the digital isolator device U203 on a second side of the digital isolator device U203. It is noted that the ground potential GND O that is provided to ground terminals of the digital isolator device U203 on the second side of the digital isolator device U203 is different from the ground potential GND 2 that is provided to ground terminals of the digital isolator device U203 on the first side of the digital isolator device U203.

[0037] An input channel A terminal of the digital isolator device U203 is electrically coupled to the signal line for the SCLK signal. An input channel B terminal of the digital isolator device U203 is electrically coupled to the signal line for the MOSI signal. An input channel C terminal of the digital isolator device U203 is electrically coupled to a signal line for the CSI 2 signal. Also, the input channel C terminal of the digital isolator device U203 is electrically coupled to a first input terminal of a buffer device U205.

[0038] An output channel terminal of the digital isolator device U203 is electrically coupled to a second input terminal of the buffer device U205. A ground terminal of the buffer device U205 is electrically coupled to the ground potential GND O that is provided to the ground terminals of the second side of the digital isolator device U203. An output terminal of the buffer device U205 is coupled to the signal line for the MISO signal.

[0039] The voltage VT3 is also provided to a first input channel terminal of an A / D converter device U207 via resistors R222, R223, R225, and R226, which are electrically connected in series. A resistor R227 is electrically coupled between the first input channel terminal of the A / D converter device U207 and a second input channel terminal of the A / D converter device U207. The voltage VT4 is provided to the second input channel terminal of the A / D converter device U207 via resistors R228, R229, R231, and R232, which are electrically connected in series.

[0040] A third input channel terminal of the A / D converter device U207 and a fourth input channel terminal of the A / D converter device U207 are electrically connected to a groundterminal of the A / D converter device U207, which electrically coupled to ground terminals on a first side of a digital isolator device U206.

[0041] A capacitor C224 is electrically coupled between the first input channel terminal of the A / D converter device U207 and a ground potential GND 3, which is at the same potential as the ground terminal of the A / D converter device U207. A capacitor C225 is electrically coupled between the first input channel terminal of the A / D converter device U207 and the second input channel terminal of the A / D converter device U207. A capacitor C226 is electrically coupled between the second input channel terminal of the A / D converter device U207 and the ground terminal of the second channel of the A / D converter device U207.

[0042] Notably, a resistor R224 is electrically coupled between the second input channel terminal of the A / D converter device U207 and a power supply terminal of the A / D converter device U207 through which the A / D converter device U207 receives power to operate. In addition, a resistor R230 is electrically coupled between the second input channel terminal of the A / D converter device U207 and the ground terminal of the A / D converter device U207. The resistors R224 and R230 are bias resistors that bias the voltage input to the second input channel terminal of the A / D converter device U207 halfway between the voltage at the power supply terminal of the A / D converter device U207 and the voltage at the ground terminal of the A / D converter device U207, which advantageously provides a great deal of fault tolerance.

[0043] A capacitor C218, a capacitor C219, and a capacitor C220 are electrically connected in parallel between the power supply terminal of the A / D converter device U207 and the ground potential GND 3, which is at the same potential as the ground terminal of the A / D converter device U207. The power supply terminal of the A / D converter device U207 is electrically coupled to an isolated supply voltage terminal of a digital isolator device U206, which is electrically coupled to a selection terminal of the digital isolator device U206. An output channel A terminal of the digital isolator device U206 is electrically coupled to a serial clock input terminal of the A / D converter device U207. An output channel B terminal of the digital isolator device U206 is electrically coupled to a serial data input terminal of the A / D converter device U207. An output channel C terminal of the digital isolator device U206 is electrically coupled to a chip select terminal of the A / D converter device U207.

[0044] A capacitor C221, a capacitor C222, and a capacitor C223 are electrically coupled in parallel between a supply voltage terminal of the digital isolator device U206, which is electrically coupled to a supply voltage (e.g., 5 V), and the ground potential GND 0 that is provided to ground terminals of the digital isolator device U206 on a second side of the digitalisolator device U206. It is noted that the ground potential GND O that is provided to ground terminals of the digital isolator device U206 on the second side of the digital isolator device U206 is different from the ground potential GND 3 that is provided to ground terminals of the digital isolator device U206 on the first side of the digital isolator device U206.

[0045] An input channel A terminal of the digital isolator device U206 is electrically coupled to the signal line for the SCLK signal. An input channel B terminal of the digital isolator device U206 is electrically coupled to the signal line for the MOSI signal. An input channel C terminal of the digital isolator device U206 is electrically coupled to a signal line for the CSI 3 signal. Also, the input channel C terminal of the digital isolator device U206 is electrically coupled to a first input terminal of a buffer device U208.

[0046] An output channel terminal of the digital isolator device U206 is electrically coupled to a second input terminal of the buffer device U208. A ground terminal of the buffer device U208 is electrically coupled to the ground potential GND O that is provided to the ground terminals of the second side of the digital isolator device U206. An output terminal of the buffer device U208 is coupled to the signal line for the MISO signal.

[0047] The dashed line in Figure 2B represents an isolation barrier. Devices on the right side of the dashed line use the ground potential GND O as a reference potential, and devices on the left side of the dashed line use ground potentials that are different from the ground potential GND O. More particularly, devices on the left side of the dashed line connected to the A / D converter device U201 use the ground potential GND l as a reference potential, devices on the left side of the dashed line connected to the A / D converter device U204 use the ground potential GND 2 as a reference potential, and devices on the left side of the dashed line connected to the A / D converter device U207 use the ground potential GND 3 as a reference potential. Accordingly, the stack voltage measurement device 204 shown in Figure 2B effectively includes four different isolation zones, each of which uses a different reference potential. The devices on the left side of the dashed line are not completely isolated from each other due to the resistor network that couples them together; however, as far as measurements of the various voltages VT1, VT2, VT3, and VT4 are concerned, they are isolated.

[0048] Figure 2C is a diagram of the stack voltage measurement module 206 of the monitoring system shown in Figure 2A. The configuration is like that of stack voltage measurement module 204 shown in Figure 2B, with similar parts being numbered in a 300 series rather than 200. The voltages VT4 and VT5 are provided to first and second input channel terminals of A / D converter device U301, respectively, while voltages VT5 and VT6 are providedto first and second input channel terminals of A / D converter device U304, respectively, and voltages VT6 and VT7 are provided to first and second input channel terminals of A / D converter device U307, respectively.

[0049] The signal lines for the CSI 4, CSI 5 and CSI 6 signals are connected to digital isolator devices U300, U303 and U306 respectively, as described above with respect to the connections between CSI l, CSI_2 and CSI_3 signals and digital isolator devices U200, U203 and U206 respectively.

[0050] Having described the structure of the monitoring system 200, operation of the monitoring system 200 will now be described. The controller 202 periodically obtains signal values corresponding to the voltages VT1, VT2, VT3, VT4, VT5, VT6, and VT7 from the analog-to-digital converters U201, U204, U207, U301, U304, and U307 using the SPI standard, as described above. Also, the controller 202 calculates (or controls the analog-to-digital converters U201, U204, U207, U301, U304, and U307 to calculate) values corresponding to the difference between the voltages VT1 and VT2, which is the voltage across the fuel cell stack 106, the difference between the voltages VT2 and VT3, which is the voltage across the fuel cell stack 108, the difference between the voltages VT3 and VT4, which is the voltage across the fuel cell stack 110, the difference between the voltages VT4 and VT5, which is the voltage across the fuel cell stack 112, the difference between the voltages VT5 and VT6, which is the voltage across the fuel cell stack 114, and the difference between the voltages VT6 and VT7, which is the voltage across the fuel cell stack 114.

[0051] Notably, each of the voltages VT2, VT3, VT4, VT5, and VT6 is measured by two different analog-to-digital converter devices, wherein the paths between each of the voltages VT2, VT3, VT4, 5, and VT6 from the connector CN200 to the two different analog-to-digital converter devices use resistors with different values.

[0052] For example, the voltage VT2 is the most negative potential of the fuel cell stack 106, and also is the most positive potential of the fuel cell stack 108. The voltage VT2 is provided to the analog-to-digital converter device U201 along a first path that includes resistors R206, R207, R209, and R210 electrically coupled in series, wherein each of the resistors R206, R207, R209, and R210 has a value of 294 KOhm. Also, the voltage VT2 is provided to the analog-to-digital converter device U204 along a second path that includes the resistors R211, R212, R213, and 214 electrically coupled in series, wherein each of the resistors R211, R212, R213, and 214 has a value of 237 KOhm. The controller 202 (or the analog-to-digital converter device U201) calculates the voltage across the fuel cell stack 106 using the values of the voltagesVT1 and VT2 measured by the analog-to-digital converter device U201, and the controller 202 (or the analog-to-digital converter device U204) calculates the voltage across the fuel cell stack 108 using the values of the voltages VT2 and VT3 measured by the analog-to-digital converter device U204. The controller 202 calculates the difference between the resulting values of the voltage across the fuel cell stack 106 and the voltage across the fuel cell stack 108. If the wire 120 that provides the voltages VT2 is loose or disconnected, the calculated voltage drop across the fuel cell stack 106 would be much greater than the calculated voltage drop across the fuel cell stack 108. Accordingly, if the difference is greater than a predetermined threshold value, the controller 202 determines that there is an anomalous condition, such as the wire 120 that provides the voltages VT2 being loose or disconnected, and sends a control signal to the fuel cell controller 204, which causes the fuel cell controller 204 to shut down operation of the stack of fuel cells 202.

[0053] It is noted detection of a loose wire would not be possible if the resistors R200, R201, R203, R204, R206, R207, R209, and 210 have the same values as the R211, R212, R213, 214, R217, R218, R220, and 221. If the values of those resistors is equal, and the wire 120 that provides the voltages VT2 is loose or disconnected, the calculated voltage drop across the fuel cell stack 106 would be the same as the calculated voltage drop across the fuel cell stack 108. Accordingly, the controller 202 would not be able to determine that there is an anomalous condition, such as the wire 120 that provides the voltages VT2 being loose or disconnected.

[0054] The various embodiments described above can be combined to provide further embodiments. All of the U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and / or listed in the Application Data Sheet, including U.S. Provisional Patent Application No. 63 / 703,851, filed on October 4, 2024, are incorporated herein by reference, in their entirety. Aspects of the embodiments can be modified, if necessary to employ concepts of the various patents, applications and publications to provide yet further embodiments. For example, although detection of anomalous conditions is described as being performed by the controller 202, the controller 202 could provide measured values to a different device (e.g., via a CAN bus to a central controller that controls operation of multiple strings of fuel cell stack) that uses those values to detect anomalous conditions.

[0055] These and other changes can be made to the embodiments in light of the abovedetailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, butshould be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.

Claims

CLAIMS1. A monitoring system, comprising: a first connector terminal which, in operation, is electrically coupled to a first monitored device in a string of monitored devices; a second connector terminal which, in operation, is electrically coupled to the first monitored device and a second monitored device in the string of monitored devices; a third connector terminal which, in operation, is electrically coupled to the second monitored device and a third monitored device in the string of monitored devices; a fourth connector terminal which, in operation, is electrically coupled to the third monitored device in the string of monitored devices; a first anal og-to-digi tai conversion device including a first input terminal and a second input terminal; a second analog-to-digital conversion device including a first input terminal and a second input terminal; one or more first resistors electrically coupled between the first connector terminal and the first input terminal of the first analog-to-digital conversion device; one or more second resistors electrically coupled between the second connector terminal and the second input terminal of the first analog-to-digital conversion device; and one or more third resistors electrically coupled between the second connector terminal and the first input terminal of the second analog-to-digital conversion device; one or more fourth resistors electrically coupled between the third connector terminal and the second input terminal of the second analog-to-digital conversion device, wherein a resistance of the one or more second resistors is different from a resistance of the one or more third resistors, wherein the first analog-to-digital conversion device, in operation, outputs a first digital value corresponding to a difference between an analog voltage at the first input terminal of the first analog-to-digital conversion device and a second analog voltage at the second input terminal of the first analog-to-digital conversion device, and wherein the second analog-to-digital conversion device, in operation, outputs a second digital value corresponding to a difference between an analog voltage at the first input terminal of the second analog-to-digital conversion device and an analog voltage at the second input terminal of the second analog-to-digital conversion device.

2. The monitoring system according to claim 1, wherein the one or more first resistors includes a plurality of first resistors electrically coupled in series, wherein the one or more second resistors includes a plurality of second resistors electrically coupled in series, and wherein the one or more third resistors includes a plurality of third resistors electrically coupled in series.

3. The monitoring system according to claim 2, wherein each of the first resistors and each of the second resistors has a first resistance, and wherein each of the third resistors has a second resistance that is different from the first resistance.

4. The monitoring system according to claim 1, further comprising: a fifth resistor electrically coupled between the second input terminal of the first analog- to-digital conversion device and a power supply terminal of the first analog-to-digital conversion device; and a sixth resistor electrically coupled between the second input terminal of the first analog- to-digital conversion device and a ground terminal of the first analog-to-digital conversion device, wherein a resistance of the fifth resistor is equal to a resistance of the sixth resistor.

5. The monitoring system according to claim 4, further comprising: a seventh resistor electrically coupled between the second input terminal of the second analog-to-digital conversion device and a power supply terminal of second first analog-to-digital conversion device; and an eighth resistor electrically coupled between the second input terminal of the second analog-to-digital conversion device and a ground terminal of the second analog-to-digital conversion device, where a resistance of the seventh resistor is equal to a resistance of the eighth resistor.

6. The monitoring system according to claim 1, further comprising: a fifth resistor electrically coupled between the first input terminal of the first analog-to- digital conversion device and the second input terminal of the first analog-to-digital conversion device; and a sixth resistor electrically coupled between the first input terminal of the second analog- to-digital conversion device and the second input terminal of the second analog-to-digital conversion device, where a resistance of the fifth resistor is different from a resistance of the sixth resistor.

7. The monitoring system according to claim 1, further comprising: a controller electrically coupled to the first analog-to-digital conversion device and the second analog-to-digital conversion device; a wire electrically coupled to the controller; and a network interface electrically coupled to the wire, wherein the network interface includes a plurality of pairs of pins, wherein an address used by the network interface is based on whether each of the pairs of pins is electrically coupled together with a jumper.

8. The monitoring system according to claim 1, further comprising: a controller which, in operation detects a loose connection of a wire electrically coupled to at least one of the first monitored device, the second monitored device, or the third monitored device based on the first digital value output by the first analog-to-digital conversion device and the second digital value output by the second analog-to-digital conversion device, wherein the controller, in operation, transmits a control signal in response to detecting the loose connection.

9. The monitoring system according to claim 8, wherein the controller, in operation, detects the loose connection if a difference between the first digital value output by the first analog-to-digital conversion device and the second digital value output by the second analog-to-digital conversion device is greater than a threshold value.

10. The monitoring system according to claim 1, further comprising: a third analog-to-digital conversion device including a first input terminal and a second input terminal; one or more fifth resistors electrically coupled between the third connector terminal and the first input terminal of the third analog-to-digital conversion device; one or more sixth resistors electrically coupled between the fourth connector terminal and the second input terminal of the third analog-to-digital conversion device, wherein the third analog-to-digital conversion device, in operation, outputs a third digital value corresponding to a difference between an analog voltage at the first input terminal of the third analog-to-digital conversion device and a second analog voltage at the second input terminal of the third analog-to-digital conversion device.

11. A method of operating a monitoring system, the method comprising: electrically coupling a first connector terminal to a first monitored device in a string of monitored devices; electrically coupling a second connector terminal to the first monitored device and a second monitored device in the string of monitored devices; electrically coupling a third connector terminal to the second monitored device and a third monitored device in the string of monitored devices; electrically coupling a fourth connector terminal to the third monitored device in the string of monitored devices; electrically coupling one or more first resistors between the first connector terminal and a first input terminal of a first analog-to-digital conversion device; electrically coupling one or more second resistors between the second connector terminal and a second input terminal of the first analog-to-digital conversion device; and electrically coupling one or more third resistors between the second connector terminal and a first input terminal of a second analog-to-digital conversion device; electrically coupling one or more fourth resistors between the third connector terminal and a second input terminal of the second analog-to-digital conversion device, wherein a resistance of the one or more second resistors is different from a resistance of the one or more third resistors, outputting, by the first analog-to-digital conversion device a first digital value corresponding to a difference between an analog voltage at the first input terminal of the firstanalog-to-digital conversion device and a second analog voltage at the second input terminal of the first analog-to-digital conversion device, and outputting, by the second analog-to-digital conversion device, a second digital value corresponding to a difference between an analog voltage at the first input terminal of the second analog-to-digital conversion device and an analog voltage at the second input terminal of the second analog-to-digital conversion device.

12. The method according to claim 11, wherein the one or more first resistors includes a plurality of first resistors electrically coupled in series, wherein the one or more second resistors includes a plurality of second resistors electrically coupled in series, and wherein the one or more third resistors includes a plurality of third resistors electrically coupled in series.

13. The method according to claim 12, wherein each of the first resistors and each of the second resistors has a first resistance, and wherein each of the third resistors has a second resistance that is different from the first resistance.

14. The method according to claim 11, further comprising: electrically coupling a fifth resistor between the second input terminal of the first analog- to-digital conversion device and a power supply terminal of the first analog-to-digital conversion device; and electrically coupling a sixth resistor between the second input terminal of the first analog- to-digital conversion device and a ground terminal of the first analog-to-digital conversion device, wherein a resistance of the fifth resistor is equal to a resistance of the sixth resistor.

15. The method according to claim 14, further comprising: electrically coupling a seventh resistor between the second input terminal of the second analog-to-digital conversion device and a power supply terminal of second first analog-to-digital conversion device; and electrically coupling an eighth resistor between the second input terminal of the second analog-to-digital conversion device and a ground terminal of the second analog-to-digital conversion device, where a resistance of the seventh resistor is equal to a resistance of the eighth resistor.

16. The method according to claim 11, further comprising: electrically coupling a fifth resistor between the first input terminal of the first analog-to- digital conversion device and the second input terminal of the first analog-to-digital conversion device; and electrically coupling a sixth resistor between the first input terminal of the second analog- to-digital conversion device and the second input terminal of the second analog-to-digital conversion device, where a resistance of the fifth resistor is different from a resistance of the sixth resistor.

17. The method according to claim 11, further comprising: electrically coupling a controller to the first analog-to-digital conversion device and the second analog-to-digital conversion device; electrically coupling a wire to the controller; and electrically coupling a network interface to the wire, wherein the network interface includes a plurality of pairs of pins, wherein an address used by the network interface is based on whether each of the pairs of pins is electrically coupled together with a jumper.

18. The method according to claim 11, further comprising: detecting a loose connection of a wire electrically coupled to at least one of the first monitored device, the second monitored device, or the third monitored device based on the first digital value output by the first analog-to-digital conversion device and the second digital value output by the second analog-to-digital conversion device; and transmitting a control signal in response to the detecting the loose connection.

19. The method according to claim 18, wherein the detecting includes detecting that a difference between the first digital value output by the first analog-to-digital conversion device and the second digital value output by the second analog-to-digital conversion device is greater than a threshold value.

20. The method according to claim 11, further comprising: electrically coupling one or more fifth resistors between the third connector terminal and a first input terminal of a third analog-to-digital conversion device; electrically coupling one or more sixth resistors between the fourth connector terminal and a second input terminal of the third analog-to-digital conversion device; and outputting, by the third analog-to-digital conversion device, a third digital value corresponding to a difference between an analog voltage at the first input terminal of the third analog-to-digital conversion device and a second analog voltage at the second input terminal of the third analog-to-digital conversion device.

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