FORM 2
THE PATENT ACT 1970 (as amended)
[39 OF 1970]
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
[See Section 10; Rule 13]
TITLE: “SYSTEM AND METHOD FOR MONITORING AND CONTROLLING FUEL CELL POWER PLANT IN A VEHICLE”
Name and address of the Applicant:
TATA MOTORS LIMITED, an Indian company having its registered office at
Bombay house, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001, Maharashtra,
INDIA.
Nationality: INDIAN
The following specification particularly describes the nature of the invention and the manner in which it is to be performed.

TECHINCAL FIELD
Embodiments of the present disclosure relate to fuel cell stack. More particularly, the embodiments relate to monitoring and controlling parameters of a fuel cell stack.
BACKGROUND OF DISCLOSURE
Fuel cell is defined as an electrochemical cell that directly converts chemical energy of a fuel into electrical energy. Unlike a conventional battery, the fuel cell can continuously produce electricity as long as the fuel and air are supplied thereto. Hydrogen is used as the fuel of the fuel cell includes pure hydrogen and reformed hydrogen produced by a reforming process using a hydrocarbon such as methane or ethanol. Although the pure oxygen improves efficiency of the fuel cell, there may be a problem that additional cost and undesirable increase of weight are entailed for providing a tank for the pure oxygen.
In the fuel cell system more hydrogen is supplied than the stochiometric ratio to the anode compartment of the fuel cell stack to prevent fuel cell stack for starving of hydrogen. During operation of fuel cell stack, hydrogen consumed and there is condensation water vapour to liquid water and also accumulation of inert gases like nitrogen as impurities which needs to be purged continuously or periodically. There is also requirement for recirculation of excess hydrogen in the anode compartment to the fuel cell stack.
Further, the condensed water from anode and water flooded from electrode which had crossed over from cathode to anode due to concentration gradient needs to be purged out periodically at regular intervals. And purging is also required to remove the accumulated of impurities like inert gases like nitrogen during the generation and compression and dispensing of hydrogen. There is also purging requirement during startup for removal of entrapped air and also flushing out of hydrogen from anode during emergency shutdown.
At higher operating temperatures, the fuel cell voltage increases at a given operating current density because higher the operating temperature the more active the reactants. The higher the operating temperature the water vapor present is more in the reactant stream to maintain a given relative humidity. This makes it more difficult to maintain a

relative humidity at or near 100%. The higher the stack outlet temperature, the more water is evaporated in the stack, which reduces the heating load on the coolant system. Hence, the higher the temperature the more water can be evaporated. Heat is absorbed in evaporating the water; all the heat used in evaporation is heat that would otherwise have to be rejected by the coolant system.
Lower operating temperatures of the fuel cell stack results in longer stack life, which is due to better humidification. Operation at lower stack temperatures may result in water management problems. Reducing the amount of water vapor required to achieve 100% RH (relative humidity) is a mixed blessing; if the RH exceeds 100%, due to water formation in the cathode or water crossover in the anode, water droplets will form. If the quantity of liquid water present is more, it can block the cell channels and result in cell starvation.
In light of forgoing discussion, there is a need to control the parameters i.e. hydrogen and air pressure, temperature of the fuel cell stack and remove the impurities from the fuel cell stack system.
STATEMENT OF THE DISCLOSURE
Accordingly the present disclosure provides a system to monitor and control fuel cell power plant in a vehicle comprising a fuel cell stack to provide power supply to the vehicle; hydrogen storage system interfaced with a control unit to store and supply hydrogen fuel at predefined state to the fuel cell stack; an air subsystem interfaced with the control unit to provide air supply to the fuel cell stack; thermal management system interfaced with the control unit to control temperature of the fuel cell stack; wiring harness to provide connectivity between plurality of equipments of the fuel cell power plant; and the control unit to monitor and control the hydrogen and air supply, and temperature of the fuel cell stack; and the disclosure also provides for a method of monitoring and controlling fuel cell power plant in a vehicle, said method comprising acts of estimating current value based on power supply requirement of the vehicle and auxiliaries of the fuel cell power plant; generating control signals by the controller for predefined parameters of corresponding components of the fuel cell plant based on the

current value; monitoring the predefined parameters using plurality of corresponding sensors and comparing said parameter values with predefined values; and maintaining the parameters with in specified limits else generating alarm to alert and switch OFF system if the parameters value exceeds predefined values by varying the operating conditions to control the fuel cell power plant.
OBJECTIVES OF THE DISCLOSURE
The main object of the instant disclosure is to obviate the above mentioned drawbacks.
Another object of the present disclosure is to provide a system to monitor and control parameters of a fuel cell power plant.
Yet another object of the present disclosure is to provide a method for monitoring and controlling parameters of a fuel cell power plant.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
The novel features and characteristic of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:
Figure 1 illustrates a system block diagram of a fuel cell power plant in a vehicle, as one embodiment.
Figure 2 illustrates flow chart for a method of controlling the parameters of the fuel cell power plant in a vehicle.
Figure 3 illustrates a block diagram of the control unit and the fuel cell power plant.
Figure 4 illustrates a system for recirculation and hydrogen and bleeding of impurities in hydrogen subsystem.

Figure 5 illustrates the block diagram to thermal management system to control the temperature of the fuel cell stack.
The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION
The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.
To overcome the drawbacks mentioned in the background, a fuel cell stack is regulated by varying pressure and flow rate of the fuel, oxidant and coolant, using which the fuel cell stack is operated. In addition, the gases in the fuel cell stack must be humidified and the coolant temperature must be controlled. To achieve the said objectives, the fuel cell stack is surrounded by a fuel system, fuel delivery system, air system, stack cooling system and humidification system. Also, the fuel cell stack system during operation, the

output power generated must be conditioned and absorbed by a load. If unsafe operating conditions occur suitable alarms must shut down the process and a cell voltage monitoring system must monitor fuel cell stack performance. These functions are performed by electrical and control systems.
Figure 1 shows an exemplary block diagram of the fuel cell power plant system as one embodiment. The major components of the fuel cell plant system are hydrogen storage system consisting of fuel cell stack 102, hydrogen storage and regulation system 106 and hydrogen module or subsystem 104; air module or subsystem 108; and thermal management system comprising of radiator 110, coolant tank 114 and coolant pump 112.
The hydrogen storage and regulation system 106 receives hydrogen fuel, stores it and dispenses. The fuel or hydrogen storage system consists of a fuelling circuit, the storage cylinders, a high pressure circuit and a motive pressure circuit. The hydrogen storage and regulation system consists of hydrogen cylinder to receive and store the hydrogen fuel, pressure relief valve to monitor the pressure of hydrogen fuel, electrically activated solenoid valve to supply the hydrogen to the fuel cell stack, high pressure regulator and a dome loaded regulator to control the flow rate of hydrogen and plurality of mechanical interface blocks for mounting plurality of sensors. The sensors measure the temperature and pressure of the hydrogen.
The hydrogen module or subsystem 104 provides hydrogen fuel to the fuel cell stack 102, at the required temperature, pressure, humidity, and flow rate. The hydrogen subsystem also removes anode waste gases and water. The hydrogen subsystem delivers hydrogen safely, in the correct amount, at the right state i.e. pressure, temperature, humidity to the fuel cell stack. Also, the hydrogen subsystem removes the excess hydrogen required for purging in a safe and efficient manner by delivering it to the air subsystem.
As shown in figure 4, the hydrogen subsystem 104 consists of hydrogen flow meter to control the flow of hydrogen fuel, a hydrogen recirculation blower 404 provided in between anode compartment 102a of the fuel cell stack 102 and the hydrogen circulation line 408 for recirculating the hydrogen through the humidification system 410. The fuel

cell stack 102 consists of an anode compartment 102a and a cathode compartment 102b. The humidification system 410 humidifies the hydrogen before supplying to the fuel cell stack 102. A check valve 406 is placed in between the hydrogen recirculation blower 404 and the hydrogen circulation line 408 to provide a unidirectional flow of recirculated hydrogen. The check valve 406 also increases a pressure of re-circulating hydrogen.
A nitrogen storage and delivery subsystem (416) is provided in the hydrogen subsystem 104 for storing and supplying nitrogen to a fuel cell stack (102) through a solenoid valve (414a) and a humidification system (410) via hydrogen circulation line (408). The nitrogen storage and delivery sub system (416) comprises a nitrogen cylinder for storing a nitrogen gas, electrically actuated solenoid valve (414a) for supplying nitrogen to a fuel cell stack (102) to flush out inert gases. A hydrogen purging and diffusing system 412 provided in between the fuel cell stack 102 and the hydrogen recirculation blower 404 for removal of condensed water and accumulated impurities from the fuel cell stack 102. The hydrogen purging and diffusing system 412 comprises a bleed valve 418 for purging condensed water accumulated in anode compartment 102a of the fuel cell stack 102 and water flooded from cathode compartment to anode compartment. A solenoid valve 414c is used to flush out accumulated impurities and entrapped air through the purge diffuser with fan.
Hydrogen when excess at the anode compartment 102a will be directed to the hydrogen recirculation blower 404 for recirculation. In between anode outlet and hydrogen recirculation blower, constantly purging bleed valve 418 and electrically actuated solenoid valve 414c are provided for purging accumulated impurities and entrapped air. The electrically actuated solenoid valve can be activated based on requirement.
The air subsystem 108 delivers required amount of air to the fuel cell stack safely. Also, the delivered air is in the required amount, at appropriate state i.e. pressure, temperature, humidity. The air subsystem comprises of air mass flow meter to control the flow of air into the fuel cell stack, air compressor is connected to the heater and water dispensing system 110 for supplying required air flow based on power supply demand. Mechanical interface blocks are provided for mounting temperature, pressure and humidity sensors.

The air which is in excess quantity from the cathode compartment is saturated air. Water condenser extracts the water from that air and passes condensed air to the self regulating air throttle valve and condensed water to water tank. The water from the water tank will be further used in humidifiers. Self regulating air throttle valve creates required back pressure for cathode compartment.
Thermal management system (110, 112 and 114) removes heat from the fuel cell stack and regulates output power. Also, the thermal management system provides regulated power to balance of power plant equipment. The fuel cell stack is required to be maintained within acceptable temperature levels i.e. in between 65oC and 75oC.
As shown in the figure 5, the thermal management system comprises a radiator 110 connected to an inlet of the fuel cell stack 102. The radiator 110 consisting of plurality of fans to reduce heat from the fuel cell stack 102. A coolant pump 112 connected to the fuel cell stack 102 to circulate coolant from the coolant tank 114 to the fuel cell stack 102. An air compressor 108 is connected to the heater and water dispensing system 502 for supplying required air flow to the system based on demand. A humidification system or humidifier 504 is connected to the heater and water dispensing system to humidify the air and takes required heat for humidification from the hot fluid coming out of the stack. A temperature sensor 506 connected to an outlet of the fuel cell stack 102 to measure temperature of the coolant coming out of the fuel cell stack. The heater and water dispensing system 502 connected to the coolant pump 112 to heat the coolant. A controller is connected to the coolant pump to monitor the temperature of the fuel cell stack 102. The controller 112 receives temperature level from the temperature sensor 108, calculates temperature variation by comparing received temperature level with predefined temperature level at a given time to switch ON or OFF predetermined number of radiator fans to control the temperature of the fuel cell stack 102.
The fuel cell stack generates continuous power if its operating temperature is more than specified limit of around 40oC. At the start of the vehicle in cold ambient temperature, which is below to the specified limit, so in order to start the vehicle heater is used to heat

the coolant and raise the system temperature by certain degree and meet the requirement. Thus the fuel cell stack is maintained in the temperature range between 65oC to 75oC for better functionality, and increase in durability and life of the fuel cell stack. As the fuel cell stacks generate power, heat is generated as a by-product. The heat generated is proportional to the generated power. The generated heat is removed from the system by using a radiator or a cooling system by switching on plurality of fans.
Wiring harness 118 provides the connectivity of power plant equipments, sensors and transducers to controller. The wiring harness will take care of powering of equipments and sensors. Based on the controller signals, it passes the signals to the corresponding components in the system. The wiring harness senses the data from the sensors and sends them to controller. Wiring harness comprises of relays, CAN cable, converter’s such as current to voltage, voltage to current converter, current booster, and voltage dividers and fuses. The wiring harness 118 is connected with hardware in loop block 120 to perform calculations and store data and instructions and control the operation of the fuel cell system. The control system consists of sensors, transducers and hardware in loop 120. During the operation of fuel cell stack system, the output power generated is conditioned and absorbed by a load bank 116.
The block diagram of the fuel cell power plant controlled by a control unit or controller 216 is illustrated in figure 2. The controller receives input signals from the sensors and transducers 214 connected to the components or equipments 202 of the fuel cell power plant, and controls the respective components based on the values sensed.
Air module subsystem 108 assess air flow rate required to be maintained based on the signal for power demand. Hence, there is a need for finer control of air flow into the fuel cell in order to prevent the fuel cell stack from starvation of oxygen. Even at cathode side input of fuel cell stack required highly humid air i.e. around 90 to 100 % RH. Therefore, the controller generates RPM signals from power demand and air compressor 204 gets the signals from controller 216 which provides the RPM rate at which it has to be run to get demanded power. Air compressor 204 blows the required quantity of pressurized air to the air humidifier with required pressure. The air humidifier gets the air from

compressor and vaporized water from water dispensing system and produces humid air. The humid air is passed to the cathode compartment of fuel cell stack with little pressure drop.
The hydrogen subsystem 104 regulates the flow of hydrogen to the fuel cell stack, as per the power demand. The flow rate is controlled by adjusting the dome loaded pressure regulator in the subsystem. Dome loaded pressure regulator senses the activation pressure from air compressor output. Hence, there is a need for finer control of hydrogen flow into the fuel cell in order to prevent the fuel cell stack from starvation of hydrogen. Thus, the controller strategy has to account for regulating the pressure of hydrogen in hydrogen subsystem as per the load requirements and pressure balancing between anode compartment and cathode compartment.
The pressures of anode and cathode compartments of the fuel cell stack are measured using pressure transducers. The flow rate of hydrogen can be controlled based on the power requirement, the required hydrogen pressure maintained can be estimated and pressure of hydrogen can be adjusted with the help of dome loaded pressure regulator or electronumetic pressure regulator. The signal from the pressure transducer in the cathode compartment could be used as input for regulating the pressure of hydrogen in the anode compartment. Thus, the methods ensure supply of hydrogen is adequate to the fuel cell stack and hydrogen pressure is maintained to avoid stack from hydrogen starvation. Also, the pressure balancing between anode and cathode compartments is maintained. Dome loaded pressure regulator passes the hydrogen to the hydrogen humidifier, where it gets humidified and goes to the anode compartment of fuel cell stack.
The controller 216 is connected to the coolant pump 206 to monitor the temperature of the fuel cell stack. The controller 216 receives temperature levels from the temperature sensor connected to an outlet of the fuel cell stack. The controller calculates temperature variation by comparing received temperature level with predefined temperature level at a given time to switch ON or OFF predetermined number of radiator fans to control the temperature of the fuel cell stack.

The controller monitors the relative humidity value in the fuel cell power plant, compares the monitored values with the set limit. Based on the comparison of relative humidity, the controller starts or stops the dosing pump 212.
Figure 3 illustrates a method for monitoring and controlling parameters of fuel cell power plant in a vehicle as a flow chart 300. The following are the steps: At step 302, power demand from vehicle and at step 304 power demand from auxiliaries of fuel cell power plant are measured or estimated, combining both the power demands obtains the total power demand for the fuel cell power plant. Based on the total power demand, current demand of the load is estimated as shown in the step 306 of the figure 3.
The power demand is provided by vehicle management system based on the accelerator pedal signal. The vehicle power demand plus power requirement from auxiliary systems (i.e. coolant pump, air compressor, radiator, hydrogen recirculation blower) of balance of power plant is the actual power requirement from fuel cell stack.
Based on the current demand, the controller will generate control signals to air compressor rpm as shown in step 308, coolant pump rpm as shown in step 310 and hydrogen recirculation blower controller at step 312.
At step 314, the controller monitors the parameters such as hydrogen pressure, air pressure, air and hydrogen humidity, coolant temperature, air mass flow rate, and hydrogen leak. The values of the parameters are obtained from the respective sensors.
At step 316, the controller monitors temperature value obtained from the temperature sensor i.e. the temperature of the coolant coming out of the fuel sell stack. Based on the temperature values controller sends the appropriate signal to the thermal management system as shown at step 322, which switches on the heater if the temperature is below the specified level else switches ON/ OFF the radiator fans, at step 324.
If any parameters go out of specified limit as shown in the step 324, the controller blows an alarm and shutdown the signals to the controller, which is shown in the step 326 of the

figure 3. The controller will decide on what mode it should execute the system after looking safety parameters.
At step 320, the controller monitors the relative humidity value, compares with the set limit, as shown in steps 328 and 332 of figure 3. Based on the comparison of relative humidity, the controller decides when to start the dosing pump, as shown in step 330 and stop dosing pump, as shown in step 334.
The present disclosure is not to be limited in terms of the particular embodiments described in this application, which are intended as illustrations of various aspects. Many modifications and variations can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Functionally equivalent methods and devices within the scope of the disclosure, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.
With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.
While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

We claim
1. A system to monitor and control fuel cell power plant 100 in a vehicle comprising:
a fuel cell stack 102 to provide power supply to the vehicle 122;
hydrogen storage system (104, 106) interfaced with a control unit to store and supply hydrogen fuel at predefined state to the fuel cell stack;
an air subsystem 108 interfaced with the control unit to provide air supply to the fuel cell stack;
thermal management system (110, 112 and 114) interfaced with the control unit to control temperature of the fuel cell stack;
wiring harness 118 to provide connectivity between plurality of equipments of the fuel cell power plant;
the control unit to monitor and control the hydrogen and air supply, and temperature of the fuel cell stack.
2. The system as claimed in claim 1, wherein the hydrogen storage system comprises:
hydrogen storage and regulation system 106 to store and dispense the hydrogen fuel based on power requirement of the vehicle;
hydrogen subsystem 104 to supply the hydrogen fuel to the fuel cell stack at predefined state through a solenoid valve and a humidification system via hydrogen circulation line from the hydrogen storage system.
3. The system as claimed in claim 1, wherein the hydrogen storage and regulation
system 106 comprises:
a hydrogen cylinder for storing hydrogen gas; pressure relief valve to monitor the pressure of hydrogen; electrically activated solenoid valve to supply the hydrogen to the fuel cell stack; pressure regulator and a dome loaded regulator to regulate the pressure of hydrogen and there by control the flow rate of hydrogen;
plurality of sensor interface blocks for mounting plurality of sensors.
4. The system as claimed in claim 1, wherein the hydrogen subsystem 104 comprises:

a hydrogen recirculation blower connected to the fuel cell stack for re-circulating the hydrogen through a humidification system;
a hydrogen purging and diffusing system to remove condensed water and other impurities from the fuel cell stack.
5. The system as claimed in claim 1, wherein the fuel cell power plant consists of plurality of pressure transducers to measure pressure of hydrogen in the fuel cell stack.
6. The system as claimed in claim 1, wherein the fuel cell power plant consists of plurality of temperature and humidity sensors interfaced with the control unit to measure temperature and humidity of the fuel cell stack.
7. The system as claimed in claim 1, wherein the thermal management system comprises:
a radiator 110 connected to an inlet of the fuel cell stack 102, said radiator 110 consisting of plurality of fans ranging between 1 to 12 for reducing heat from the fuel cell stack 102;
a coolant pump 112 connected to the fuel cell stack 102 through the radiator 110 to circulate coolant to the fuel cell stack;
a temperature sensor connected to an outlet of the fuel cell stack, said temperature sensor measures temperature of the coolant coming out of the fuel cell stack;
heater and water dispensing system is connected to the coolant pump to heat the coolant for faster start up of fuel cell power system requiring at ambient temperature;
a humidifier system is connected to the heater and water dispensing system and the fuel cell stack to control humidity.
8. The system as claimed in claim 7, wherein the controller switches ON the heater to heat the coolant if the temperature is less than 40º C.
9. A method of monitoring and controlling fuel cell power plant in a vehicle, said method comprising acts of:

estimating current value based on power demand of the vehicle and auxiliaries of the fuel cell power plant;
generating control signals by the controller for predefined parameters of corresponding components of the fuel cell plant based on the current value and sensor inputs;
monitoring the predefined parameters using plurality of corresponding sensors and comparing said parameter values with predefined values;
maintaining the parameters with in specified limits else generating alarm to alert and switch OFF system if the parameters value exceeds predefined values by varying the operating conditions to control the fuel cell power plant.
10. The method as claimed in claim 9, wherein the predefined parameters are at least one of hydrogen pressure, air pressure, air and hydrogen humidity’s, and coolant temperature.
11. The method as claimed in claim 9, wherein the control signals comprises of air compressor RPM for air subsystem component, coolant pump RPM for thermal management and hydrogen recirculation blower controller signal for hydrogen subsystem and control signal for water dosing pump of humidifier system.
12. The method as claimed in claim 9, wherein the components of the fuel cell plant comprises air compressor for providing air supply, coolant pump for supplying coolant to the fuel cell stack, hydrogen recirculation blower for re-circulating the hydrogen and water dosing pump for dosing water for humidification.
13. The method as claimed in claim 9, wherein the predefined value of the coolant temperature ranges between 65ºC to 75ºC.
14. The method as claimed in claim 9, wherein the predefined value of the hydrogen pressure ranges between 0 to 320 kPa, air pressure ranges between 0 to 300 kPa, and relative humidity of air and hydrogen varies between 65 to 100%.

15. A system to monitor and control fuel cell power plant in a vehicle and a method thereof are substantially as herein above described and as illustrated in accompanying drawings.