A Control System for a Fuel Cell Powered Vehicle

FIELD OF THE INVENTION

The invention generally relates to a fuel cell system in a vehicle and particularly to a control system for controlling the operation of the vehicle.

BACKGROUND

Conventional petrol and diesel engine vehicles contribute significantly to emission of green house gases. Hence, in order to meet with an increasing demand for reduction of exhaust gas emissions, fuel cells are being increasingly used in recent years. Polymer electrolyte membrane fuel cells or low temperature proton exchange membrane fuel cells, which operate at relatively low temperatures, are the most commonly used fuel cells in automotive applications. The operating temperature of these fuel cells is low as the proton exchange membrane used in said low temperature proton exchange membrane fuel cells is sensitive to increase in temperature. Therefore, vehicles employing said low temperature proton exchange membrane fuel cells are provided with air/liquid cooling in order to prevent membrane degradation due to increase in temperatures beyond the operating temperature. It is also essential to ensure that the proton exchange membrane of said low temperature proton exchange membrane fuel cells is kept moist during the reaction between fuel and air to prevent membrane degradation. Therefore, air is usually humidified before being sent into the low temperature proton exchange membrane fuel cells.

This requires the installation of humidifiers in the vehicles provided with said low temperature proton exchange membrane fuel cells. Installation of a liquid cooling system and humidifiers in the vehicle not only leads to increase in weight of the vehicle but also leads to an increase in the cost of manufacturing. The above mentioned problems can be eliminated by the use of a high temperature proton exchange membrane fuel cell (hereinafter HTPEM fuel cell). However, because of their high operating temperature, the HTPEM fuel cell needs to be heated initially by an external heat source for reaching the optimal operating temperature. As a result, electrical energy would be required to operate the external heat source and raise the temperature of said HTPEM fuel cell. Also, since said HTPEM fuel cells have a high operating temperature, electrical energy from said HTPEM fuel cells cannot be utilised to operate the vehicle during cold start conditions. Generally, electrical energy from a secondary power source is used to operate the vehicle during cold start conditions and once the HTPEM fuel cell reaches optimum operating temperature, electrical energy from said HTPEM fuel cell is used to operate the vehicle. However, for efficient functioning of a vehicle provided with both a HTPEM fuel cell and a secondary power source, it is essential to provide a control mechanism to regulate the energy flow from the HTPEM fuel cell and the secondary power source to the vehicle.

SUMMARY OF THE INVENTION

It is therefore one of the objects of the invention to provide a control system for the operation of a vehicle provided with HTPEM fuel cells and a secondary power source. The present subject matter described herein relates to a fuel cel( system in a fuel cell powered vehicle and to a control system for controlling the operation of said fuel cell powered vehicle. The fuel cell powered vehicle according to the present invention includes a motor, a secondary power source, a fuel cell system, a transmission and a control system. The fuel cell system according to the present invention includes a fuel cell stack, a fuel storage container, a pressure regulator, solenoid valves, a heater, an air blower, and a voltage converter. Further, the control system comprises a fuel eel! system controller operatively connected to the fuel cell system and to the secondary power source, and a motor controller operatively connected to the motor and the fuel cell system controller. In the present embodiment, the fuel cell stack comprises high temperature proton exchange membrane (HTPEM) fuel cells.

The fuel cell system controller operatively connected to the motor controller, receives via electronic communication signals the electrical output energy required by the motor for operation of said fuel cell powered vehicle. Depending on the output energy requirement of the motor of the fuel cell powered vehicle, the fuel cell system controller, regulates the output energy either from the fuel cell stack or the secondary power source. Thus, the control system aids in the operation of the fuel cell powered vehicle, provided with both a fuel cell stack made of HTPEM fuel cells, and a secondary power source. The foregoing objective and summary provide only a brief introduction to the present invention. To fully appreciate these and other objects of the present invention as well as the invention itself, all of which will become apparent to those skilled in the art, the following detailed description of the invention and the claims should be read in conjunction with the accompanying drawings. Throughout the specification and drawings identical reference numerals refer to identical or similar parts.

BRIEF DESCRIPTION OF DRAWINGS
Fig 1 illustrates a fuel cell powered vehicle in accordance with the present invention.

Fig 2 illustrates a system diagram of the fuel cell powered vehicle in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Exemplary embodiments of a fuel cell powered vehicle and a control system for said fuel cell powered vehicle in accordance with the present invention will be described hereunder with reference to the accompanying drawings. Various features of the fuel cell powered vehicle and the control system for said fuel cell powered vehicle in accordance to the present invention will become discernible from the following description set out hereunder. It is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Further, it is to be noted that although the present invention has been exemplified for a three wheeled fuel cell powered vehicle, however the present invention may not be restricted only to a three wheeled fuel cell powered vehicle and is applicable to any fuel cell powered vehicle including two wheeled and four wheeled fuel cell powered vehicles.

Figure 1 illustrates a perspective view of a frame structure of a fuel cell powered vehicle in accordance with an aspect of the present invention. In one embodiment of the present invention, the fuel cell powered vehicle 100 is a three wheeled vehicle as may be seen in Fig.1. The fuel cell powered vehicle 100 includes a front cabin assembly 101 and a rear cabin assembly 102. The front cabin assembly 101 includes a head pipe (not shown) that mounts a steering assembly (not shown), a main tube (not shown) that connects said head pipe to a down tube 103. Further, a driver seat assembly (not shown) is mounted above the down tube 103. The rear cabin assembly 102 includes a passenger seat assembly (not shown) which enables seating of passengers, a motor 104, a secondary power source 105, wherein the motor 104 is operatively connected to a transmission 106 (shown in Fig.2)

A fuel cell system F and the secondary power source 105 supply energy to said fuel cell powered vehicle 100. Further, a control system S controls the working of the fuel cell system F and that of the secondary power source 105 for efficient operation of said fuel cell powered vehicle 100. Figure 2 illustrates a system diagram of the fuel cell powered vehicle 100. Referring to Fig.2, description is given of the working of the fuel cell system F and that of the control system S installed in said fuel cell powered vehicle 100 in accordance with the present invention. As shown in Fig 2, the fuel cell system F includes a fuel storage container 1, a flash back arrestor 2, a pressure regulator 3, solenoid valves 4A and 4B, a fuel cell stack 5, a heater 7, a needle valve 8, an air blower 9 and a voltage converter 10. 99.99% pure fuel for example hydrogen from the fuel storage container 1 and atmospheric air from the air blower 9 are pumped into the fuel cell stack 5 in order to initiate chemical reaction inside said fuel cell stack 5. In the present embodiment, the fuel cell stack 5 is made of PBI (polybenzimidazole and phosphoric acid) based HTPEM (High Temperature Proton Exchange Membrane) fuel cells with an operating temperature ranging from 80°C to 180°C. The heater 7 is used to raise the temperature of the fuel cell stack 5 and is used to provide the required operating temperature to the fuel cell stack 5.

A flash back arrestor 2 is used to avoid the backflow of flame into the fuel cell stack 5. The pressure regulator 3 is used to regulate the inlet pressure of fuel in the fuel stack 5 and the solenoid valve 4A is used to allow/shut off fuel supply as and when required. Atmospheric air is supplied to the fuel cell stack 5 via the air blower 9 at a controlled rate. Further, the air blower 9 is also used to cool the fuel cell stack 5 when the stack temperature exceeds 180°C. Thus, when the optimal operating temperature of the fuel cell stack 5 is attained, electrical output energy is produced in the fuel cell stack 5 along with heat and water vapour. Further, electrical output from the fuel cell stack 5 will vary depending on an output of a throttle position sensor 15. Electrical energy to auxiliary electrical components such as headlamp, horn, and the like are regulated by a voltage controller 16 operatively connected to the secondary power source 105. Unreacted fuel, other gases and water vapour accumulated in the fuel cell stack 5 are purged out through the solenoid valve 4B via a needle valve 8 at regular intervals. The heat energy generated by the fuel cell stack 5, when said fuel cell stack 5 attains an optimum operating temperature for e.g. 160° is utilised to maintain a reaction temperature of the fuel cell stack 5. Further, a voltage controller 10 is used to alter an output voltage from the fuel cell stack 5.

Operation of the above described fuel cell system F is controlled by the control system S, which includes a fuel cell system controller 12. The fuel cell system controller 12 operatively connected to the fuel cell system F controls functioning of solenoid valves 4A and 4B, the heater 7, the air blower 9 by taking fuel cell stack voltage and fuel cell stack temperature as input and thereby helps to maintain the temperature inside the fuel cell stack 5 and thereby the energy output from the fuel cell stack 5. The control system S also includes a motor controller 13 operatively connected to the motor 104 and to the fuel cell system controller 12. A regulated electric supply has to be provided to the motor 104 for efficient working of the fuel cell powered vehicle 100. This is achieved by regulating the energy output from the fuel cell stack 5 to the motor 104. The motor controller 13 communicates with the fuel cell system controller 12 via electronic communication signals energy required for operation of the fuel cell powered vehicle 100. Depending on the energy or voltage requirement, the fuel cell system controller 12 controls the output voltage from the fuel cell stack 5 via the voltage converter 10. The voltage converter 10 either steps down or steps up the output voltage from the fuel cell stack 5 to supply a regulated voltage for vehicle operation.

Thus, the energy supplied by the fuel cell stack 5 as regulated the fuel cell system controller 12 is used to operate the fuel cell powered vehicle 100. However, since the fuel cell stack 5 is made of HTPEM fuel cells, electrical energy produced in the stack 5 can be utilized only when an optimal operating temperature for example 160°C is attained. Hence, only when an optimal temperature of 160°C is attained, the fuel cell stack 5 may be utilised to supply energy for vehicle operation. As a result, electrical energy from the fuel cell stack 5 cannot be used during cold start condition of the vehicle. In such conditions, electrical energy from the secondary power source 105 such as a battery which is operatively connected to the motor controller 13 is used to operate the fuel cell powered vehicle and electrical components of said vehicle. The output energy from the secondary power source 105 required for operation of the fuel cell powered vehicle 100 is controlled by the fuel cell system controller 12, which in turn receives input from the motor controller 13. However, when the fuel cell stack 5 is fully operational, the output energy from fuel cell stack 5 is used for vehicle operation and is also utilised to charge the secondary power source 6 via an inbuilt charger 11.

Thus, the electrical output energy from the fuel cell stack 5 or from the secondary power source 105, supplied to the motor 104 operatively connected to the motor controller 13 of the fuel cell powered vehicle 100 is regulated by the fuel cell system controller 12 based on inputs received from said motor controller 13. Thus, the control system S, which includes the fuel cell system controller 12 and the motor controller 13, as described above is used to regulate output energy in the fuel cell powered vehicle 100 provided with both the fuel cell stack 5 and the secondary power source 105. Thus, said fuel cell powered vehicle 100 can be operated either only on fuel cell power or only secondary power or both fuel cell power and secondary power. While the present invention has been shown and described with reference to the foregoing preferred embodiments, it will be apparent to those skilled in the art that changes in form, connection, and detail may be made therein without departing from the spirit and scope of the invention as defined in the appended claims:

We Claim:
1. A fuel cell powered vehicle (100) comprising: a motor (104); a secondary power source (105); a fuel cell system (F); and a control system (S), wherein the control system (S) comprising a fuel cell system controller (12) operatively connected to the fuel ceil system (F) and to the secondary power source (105), and a motor controller (13) operatively connected to the motor (104) and to the fuel cell system controller (12), controls operation of said fuel cell powered vehicle (100) by regulating an output energy from said fuel cell system (F) and said secondary power source (105).

2. The fuel cell powered vehicle (100) as claimed in claiml, wherein the fuel cell system (F) comprises a fuel cell stack (5), a fuel storage container (1) supplying fuel to said fuel cell stack (5), a flash back arrestor (2) to avoid backflow of flame into the fuel storage container (1), a pressure regulator (3) to control inlet of fuel into said fuel cell stack (5), a plurality of solenoid valves (4A, 4B) to allow/shut off fuel into the fuel storage container (1), a heater (7) to supply required operating temperature to said fuel cell stack (5), an air blower (9) to supply air to said fuel cell stack (5), and a voltage converter (10) to alter output voltage of said fuel cell stack (5).

3. The fuel cell powered vehicle (100) as claimed in claim 2, wherein the fuel cell stack (5) is made of polybenzimidazole and phosphoric acid based high temperature proton exchange membrane fuel cells.

4. The fuel cell powered vehicle (100) as claimed in claim 2, wherein the fuel cell stack (5) has an operating temperature in the range 80°C- 180°C.

5. A method for operating a fuel cell powered vehicle (100), said fuel cell powered vehicle (100) comprising a motor (104), a secondary power source (105), a fuel cell system (F) and a control system (S), wherein the fuel cell system (F) comprises a fuel cell stack (5) and the control system (S) comprises a fuel cell system controller (12) and a motor controller (13) operatively connected to each other, and wherein said method comprises steps of: regulating temperature of said fuel cell stack (5) by means of said fuel cell system controller (12); monitoring an input energy necessary for operation of said fuel cell powered vehicle (100) by means of the motor controller (13); communicating via electronic communication signals, the input energy necessary for operation of said fuel cell powered vehicle (100) by the motor controller (13) to the fuel cell system controller (12); controlling an output energy supplied from the secondary power source (105) via the motor controller (13) to the motor (104) by means of the fuel cell system controller (12); controlling an output energy supplied from the fuel cell stack (5) via the motor controller (13) to the motor (104) by means of the fuel cell system controller (12); and controlling an output energy supplied from the fuel cell stack (5) to the secondary power source (105) by means of the fuel cell system controller (12).

6. The method as claimed in claim 5, wherein the output energy supplied from the fuel cell stack (5) to the secondary power source (105) is controlled by means of the fuel cell system controller (12) via an inbuilt charger (11).