FIELD OF INVENTION:
[001] The present subject matter described herein, relates to an Internal 5 combustion engine with torque based engine management system and, in particular, a method and a system for alternator load modeling for Torque management of the internal combustion engine of the vehicle.
BACKGROUND AND PRIOR ART:
[002] A torque based engine management system is the one which uses a unified 10 torque demand generated by combining all the torque demands generated in the complete system. In this system a torque demand is generated by the alternator control system. This system calculates the alternator torque requirement from alternator excitation current and rotation speed. For providing these signals the alternator has to be an advanced alternator. The advanced alternator, such as LIN 15 type alternator generate variable loading signals based on the excitation current and rotation speed for fulfilling electrical power requirements of the vehicle. For example, electrical power requirements of power windows, head lamps, radiator fan, rear defogger, cooling fan, and the like. This electrical requirement adds extra load on the internal combustion engine of the vehicle and idle speed of the engine 20 fluctuates.
[003] In order to have better engine performance and better handling of the vehicle, an internal combustion engine of a vehicle must maintain a target idle speed within a specified range. Further, the internal combustion engine and the alternator are coupled with each other, therefore, load changes of the alternator 25 effects the working of the internal combustion engine. When the alternator requires more torque, the alternator increases the load requirement of the internal combustion engine. When the alternator torque load varies, the engine idle speed can fluctuate out of the specified range defined for proper engine idle stability.
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[004] In order to meet the idle speed requirements of the internal combustion engine, the engine air rate in response to the engine speed variations is modified which results in excessive engine speed fluctuation as electrical loading is applied and removed from the system.
[005] US 8129957 B2 relates to an alternator system includes a field circuit, a 5 regulator that regulates a field circuit electrical flow through the field circuit, and an output current sensor that detects an actual current output from the alternator system. The alternator system further includes a controller that communicates with the regulator to vary the field circuit electrical flow based on the actual current detected by the output current sensor. 10
[006] Figure 1 illustrates the process flow of the known alternator control system to adjust and work fluctuation in electrical loading, such as adding and removing electrical load. And providing the load requirement to the internal combustion engine. Due to sudden adding and removing electrical load requirements create fluctuation in the engine speed which decreases the stability of the engine and 15 causes noise and vibration. Figure 1 illustrates the alternator 101 having capabilities to generate torque requirement based on the electric loads. The alternator 101 is internally coupled with electronic and software module to calculate torque requirement. The alternator 101 calculates the torque demand according to requirement and sends the calculated alternator torque requirement 20 signal 105 to torque management system 106. The torque management system 106 receives the alternator torque requirement signal 105 and other torque demand signal 107 from the other sources, such as AC compressor. The torque management system 106 calculates final torque requirement of the vehicle based on the inputs of the alternator and other torque demands and sends the final torque 25 requirement to the internal combustion engine. For providing the final torque requirement, the alternator 101 must be advanced alternator with software and hardware capabilities.
[007] The disadvantage of the current system is that alternator with advanced communication technology is expensive as compared with a conventional 30
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alternator. Moreover malfunction of alternator torque management system might occur in case of failure of the excitation current sensor or alternator rotation speed sensor. The alternator torque requirement, in a torque based engine management system, is inferred by the alternator control system by using the value of alternator excitation current or stator current and alternator rotation speed. An advanced 5 alternator with hardware and software capabilities for communicating the values of excitation current and rotation speed to the alternator control system, in engine management system, is required to have both of these signals. Further, the technical problem lies with the use of conventional alternator in place of advanced alternator as a conventional alternator does not have the capability to provide the 10 excitation current and alternator rotation speed signals. Therefore, the present subject matter provides a technical solution for the above identified technical problem by providing a conventional alternator along with ECU software based excitation current signal and the speed rotation signal estimation capabilities.
OBJECTS OF THE INVENTION: 15
[008] The principal object of the present subject matter is to provide modeling of alternator system to calculate alternator torque requirement using a conventional alternator.
[009] Another object of the present subject matter is to provide a cost efficient alternator system for calculating the torque requirement of the vehicle. 20
[0010] Another object of the present subject matter is to provide an alternator system which maintains idle speed of an internal combustion engine of the vehicle.
[0011] Another object of the present subject matter is to reduce fluctuations in the internal combustion engine speed by maintaining the excitation current switch On 25 mode and Switch off mode.
SUMMARY OF THE INVENTION:
[0012] The present invention relates to a torque based engine management system which has an alternator control system coupled with conventional alternator,
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excitation current estimation module, and rotation speed estimation module for determining alternator torque requirement by calculating excitation current and alternator rotation speed, respectively. In the present torque based engine management system, the conventional alternator is coupled with the excitation current estimation module and rotation speed estimation module to determine the 5 alternator torque requirements. The excitation current estimation module and the rotation speed estimation module are provided in the Electronic Control Unit (ECU) of the vehicle. The excitation current estimation module calculates the excitation current value based on electric load ON/OFF signals from various electrical loads. The excitation current estimation module calculates the excitation 10 current for each individual electric load upon switching ON/OFF of an electrical device/load of the vehicle. After the current value for individual electrical load is calculated, the combined excitation current of the electric loads is calculated by combining the individual values of excitation current for all the electrical loads that are switched on. By combining all the electrical loads, a cumulative excitation 15 current value is generated by the excitation current estimation module. Further, the rotation speed estimation module calculates the alternator rotation speed by receiving engine speed signal and multiplying the engine speed signal by alternator pulley ratio. The alternator rotation speed estimation module sends the alternator rotation speed to the alternator control system. After receiving the 20 inputs of the excitation current and the alternator speed rotation, the alternator control system calculates to alternator torque demand based on the inputs and sends the signal of calculated alternator torque demand to the torque management system. The torque management system receives the torque demand of alternator and other systems and sends the final torque requirement to the engine. 25
[0013] In order to further understand the characteristics and technical contents of the present subject matter, a description relating thereto will be made with reference to the accompanying drawings. However, the drawings are illustrative only but not used to limit scope of the present subject matter.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0014] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the 5 accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods in accordance with embodiments of the present subject matter are now described, by way of example, 10 and with reference to the accompanying figures, in which:
[0015] Figure. 1 illustrates process flow diagram of torque based engine management system with advanced alternator, as known in the prior art;
[0016] Figure. 2 illustrates process flow diagram of torque based engine management system with conventional alternator, in accordance with an 15 embodiment of the present subject matter;
[0017] Figure. 3 illustrates ECU system architecture with excitation current estimation module and alternator rotation speed estimation module, in accordance with an embodiment of the present subject matter;
[0018] Figure. 4 illustrates excitation current estimation module architecture for 20 the conventional alternator, in accordance with an embodiment of the present subject matter;
[0019] Figure. 5 illustrate alternator rotation speed estimation module architecture for the conventional alternator, in accordance with an embodiment of the present subject matter; and 25
[0020] Figure 6 illustrates a method for calculating and managing torque demand of the conventional alternator by reducing fluctuations in the RPM of engine, in accordance with an embodiment of the present subject matter.
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[0021] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily 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. 5
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[0022] The subject matter disclosed herein relates to torque based engine management system which has an alternator control system coupled with conventional alternator, excitation current estimation module, and rotation speed estimation module for determining alternator torque requirement by calculating 10 excitation current and alternator rotation speed, respectively. In the present torque based engine management system, the conventional alternator is coupled with the excitation current estimation module and rotation speed estimation module to determine the alternator torque requirements. The excitation current estimation module and the rotation speed estimation module are provided in the Electronic 15 Control Unit (ECU) of the vehicle. The conventional alternator does not have the alternator control system for receiving and sending torque generation information. The excitation current estimation module calculates the excitation current value based on electric load ON/OFF signals from various electrical loads. The excitation current estimation module calculates the excitation current for each 20 individual electric load upon switching ON/OFF of an electrical device/load of the vehicle. After the current value for individual electrical load is calculated, the combined excitation current of the electric loads is calculated by combining the individual values of excitation current for all the electrical loads that are switched on. By combining all the electrical loads, a cumulative excitation current value is 25 generated by the excitation current estimation module. Further, the rotation speed estimation module calculates the alternator rotation speed by receiving engine speed signal and multiplying the engine speed signal by alternator pulley ratio. The alternator rotation speed estimation module sends the alternator rotation speed to the alternator control system. After receiving the inputs of the excitation 30
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current and the alternator speed rotation, the alternator control system calculates to alternator torque demand based on the inputs and sends the signal of calculated alternator torque demand to the torque management system. The torque management system receives the torque demand of alternator and other systems and sends the final torque requirement to the engine. 5
[0023] Conventionally, a torque based engine management system is the one which uses a unified torque demand generated by combining all the torque demands generated in the complete system. In this system a torque demand is generated by the alternator control system. This system calculates the alternator torque requirement from alternator excitation current and rotation speed. For 10 providing these signals the alternator has to be an advanced alternator. The disadvantage of the current system is that alternator with advanced communication technology is expensive as compared with a conventional alternator. The alternator torque requirement, in a torque based engine management system, is inferred by the alternator control system by using the 15 value of alternator excitation current or stator current and alternator rotation speed. An advanced alternator with hardware and software capabilities for communicating the values of excitation current and rotation speed to the alternator control system, in engine management system, is required to have both of these signals. 20
[0024] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that 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 subject matter. It should also be appreciated by those 25 skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the 30
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concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the 5 following description when considered in connection with the accompanying figures.
[0025] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject 10 matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0026] Figure. 2 illustrates process flow diagram of torque based engine management system, in accordance with an embodiment of the present subject 15 matter. The present torque based engine management system 200 has an alternator control system 208 for calculating the alternator torque requirement. The conventional alternator 202 is the simple hardware alternator which does not have sensors to detect the value of excitation current requirement or the alternator rotation speed, neither does the alternator have the software capability to 20 communicate with the alternator control system. The alternator control system 208 is coupled with the excitation current estimation module 203, and rotation speed estimation module 204. The alternator control system 202 receives the inputs from the excitation current estimation module 203 and the rotation speed estimation module 204 for calculating the final torque requirement of the vehicle. The 25 excitation current estimation module 203 calculates the excitation current value using electrical load signals 201 generated by various electrical loads, such as Head lamps, blower fan, radiator fan, rear defogger, etc. (are some of these hardware devices that give electrical load signals 201). The excitation current for individual electrical loads is calculated by the excitation current estimation 30
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module 203 during creation of the model by switching on one electrical load at a time and calculating the respective excitation current demand by that particular electrical load. After the current value for each or individual electrical load is calculated, the combined excitation current of the alternator is calculated by combining the individual values of excitation current for all the electrical loads 5 that are switched on. For example, the combined excitation current value 206 of electrical loads E
1, E2, E3, etc., is calculated by calibration for these electrical loads as A1, A2, A3, etc. Accordingly, for a combination of electrical loads, a cumulative excitation current value 206 is calculated by combination of plurality of excitation currents. For example, if electric loads E1 and E3 are switched on, 10 the cumulative value of excitation current value 206 is sum of A1 and A3.
[0027] Further, the rotation speed estimation module 204 calculates the alternator speed. The rotation speed estimation module 204 takes engine speed signal as an input signal 205 and multiplies the engine speed input signal 205 by alternator pulley ratio. The alternator pulley ratio is well known to a person skilled in the art 15 and it is fixed in each alternator. Therefore, explaining the alternator pulley ratio will make the subject matter complex. The rotation speed estimation module 204 provides the product which is equivalent to the alternator rotation speed 207. Based on the cumulative value of excitation current 206 and the rotation speed 207, the alternator control system 208 calculates the alternator torque requirement 20 209. After calculating the torque requirement 209, the alternator torque control system 208 sends the calculated alternator torque requirement 209 to torque management system 210. The torque management system 210 also receives torque demand 211 from other system. The torque management system 210 combines all the demands and calculates final torque demand 212 and sends the final torque 25 demand 212 to engine.
[0028] Figure. 3 illustrate Engine Control Unit (ECU) system architecture, in accordance with an embodiment of the present subject matter. The ECU architecture 300 is coupled with a plurality of electrical and hardware devices for controlling the engine. The ECU 300 is coupled with various sensors of the 30
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vehicle for receiving working information of the hardware devices. The present ECU architecture 300 illustrates alternator torque control system for calculating actual torque requirement of the vehicle by maintaining the idle speed of the vehicle. The ECU architecture 300 has excitation current estimation module 307 and alternation rotation speed estimation module 308. The excitation current 5 estimation module 307 receives electrical load on/off signals 304 from the electrical loads hardware devices 301. A plurality of input signals 304 is coming to the ECU 300 from many hardware devices 301 in the vehicular system. The vehicle has a plurality of electric devices, such as Head lamps, blower fan, radiator fan, rear defogger, etc., which give electrical load input on/off signals 304 10 to the ECU 300, in particularly to the excitation current estimation module 307 and these input signals 301 are the ON/OFF flags for these hardware devices 301. When a electrical hardware device, for example, headlamp is ON, the headlamp send an ON signal to the excitation current estimation module 307 for generation of electric energy. Similarly, when the headlamp is OFF, the headlamp sends a 15 OFF signal to the excitation current estimation module 307 for reduction in electrical energy.
[0029] The ON/OFF signals 304 of electrical load devices 301 are received by the excitation current estimation module 307. The excitation current estimation module 307 calculates the excitation current value in the system. After 20 calculation/estimation, the excitation current estimation module 307 sends the calculated excitation current value to alternator control system 311 (alternator control system 208 in the figure 2).
[0030] The alternator rotation speed estimation module 308 uses the engine speed signal 305 to calculate the alternator rotation speed. The alternator rotation speed 25 estimation module 308 receives the engine speed signal 305 from the engine speed sensor 302. After estimating the rotation speed of the alternator, the alternator rotation speed estimation module 308 sends the calculated value to the alternator control system 311 (alternator control system 208 of figure 2).
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[0031] The signals from both of the modules 307, 308 act as an input for the alternator control system 311 that calculates the torque requirement of the alternator based on the received signals from the modules 307 and 308. Similarly, there are other torque management modules 309 that calculate the torque demand for other parts 303, including AC compressor, etc. All these torque requirements 5 are calculated and managed by the overall torque management system 312 that calculates a final torque demand and gives a command of the final torque demand to the engine 312 to fulfill this torque demand.
[0032] Figure. 4 illustrate excitation current estimation module architecture, in accordance with an embodiment of the present subject matter. The excitation 10 current estimation module 400 calculates the value of excitation current based on the electric load ON/OFF signals. As illustrated in the figure 4, electrical load on/off signals 6, 7, 8 are coming from electrical load hardware 3, 4, 5. For example if an electric load 3 which is the headlamp of the vehicle, is off then its signal 6 corresponds to an ‘off’ bit. And if an electric load 5 which is the blower 15 fan of the vehicle, is on then its signal 8 corresponds to an ‘on’ bit.
[0033] Whenever an electrical load is switched on it demands some electrical energy and the alternator provides that electrical energy. The electrical energy produced by the alternator is converted from the mechanical energy of the engine. This mechanical energy requirement from the engine puts mechanical load on the 20 engine and the engine RPM falls. So, extra torque, corresponding to the alternator’s demand, has to be produced to keep stable engine RPM or engine at idle speed.
[0034] Further, the values of base excitation currents 9, 10, 11 correspond to the electrical load signals 6, 7, 8. After experiments and tests, the value of the base 25 excitation current for each load is calculated and set as base excitation current values. The engine RPM drop after switching on an electrical load is observed and the value of base excitation current for each electrical load is calculated to manage the engine RPM in stable condition and that there is no drop in the engine RPM. The excitation current value for each electrical load is calculated by switching on 30
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corresponding electrical load one by one. After calculating the value of excitation current, for each electrical load, the total base current 403 calculation is done by adding up the excitation current value for all the electrical loads that are switched on at any particular instance.
[0035] Whenever an electrical load is switched ON there is an initial excess 5 current demand just after the load is switched on, depending upon whether the electrical load is inductive or resistive type. Accordingly, initial excess excitation current requirement is calculated in the second step, i.e., initial excess current calculation step. The second step contains 3 parts, i.e., 12, 13 and 14 to calculate the initial excess excitation current requirement. The part 12 is a calculation logic 10 that estimates the value of the initial excess current required by a specific electric load when it is switched on. The part 13 is the logic for calculating the duration for which the demand for excess initial current is required. After this duration the base excitation current value is sufficient to meet the demand of the electrical load. The part 14 is the logic that calculates the rate at which the initial excess 15 current is to be changed after the initial demand duration is over. All these calculations are done experimentally for each electrical load and are fixed such that there is no fluctuation in engine revolution per minute (RPM). By this way, the present engine torque management system removes the technical problem of the conventional alternator, i.e., unstable or fluctuated engine RPM. Therefore, the 20 present torque management system uses the conventional alternator with the ECU and maintains the idle speed of the engine.
[0036] After the final value of initial excess excitation current is calculated it is added to the base excitation current 403. After adding, the final value of excitation current 402 whenever an electrical load is switched on or off is given to the 25 alternator control system for smooth functioning of the engine.
[0037] Figure 5 illustrates alternator rotation speed estimation module architecture, in accordance with an embodiment of the present subject matter. The alternator rotation speed estimation module 500 is coupled with the engine speed sensor 501 to sense the engine speed and sends engine speed signal 504 to the 30
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alternator rotation speed estimation module 500. In the alternator rotation speed estimation module 500, the engine speed signal 504 is multiplied with pulley ratio 502 of alternator pulley to calculate the required alternator rotation speed 503.
[0038] The alternator control system receives the final value of excitation current 402 and alternator rotation speed 503 to calculate the requirement of alternator 5 torque. The alternator control system sends the required demand of alternator torque to torque management system which calculates the unified torque demand for complete system and sends the final torque demand to engine.
[0039] Figure 6 illustrates a method for modeling the conventional alternator for calculating final torque requirement of the alternator, in accordance with the 10 present subject matter. At step 601, the excitation current estimation module receives the electrical load ON/OFF input signal from a plurality of electrical hardware devices. The rotation speed estimation module receives engine speed signal from the engine speed sensor. At step 602, the excitation current estimation module calculates the final excitation current based on base excitation current and 15 initial excess current. At step 603, the rotation speed estimation module calculates alternator rotation speed using the engine speed signal and alternator pulley ratio. The rotation speed estimation module multiplies the engine speed signal with pulley ratio of alternator pulley to calculate the required alternator rotation speed. At step 604, the excitation current estimation module and the alternator speed 20 estimation module sends the calculated signals to the alternator control system. The alternator control system uses the calculated signals and calculates the alternator torque requirements and sends the calculated torque requirement to the torque management system at step 605. The torque management system sends the final torque requirement to the engine for generation of torque. 25
[0040] Throughout the specification, and in the claims, the term “connected” means a direct electrical connection between the things that are connected, without any intermediate devices. The term “coupled” means either a direct electrical connection between the things that are connected, or an indirect connection through one or more passive or active intermediary devices. The term 30
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“circuit” means either a single component or a multiplicity of components, either active or passive, that are coupled together to provide a desired function.
[0041] The term “vehicle” as used throughout this detailed description and in the claims refers to any moving vehicle that is capable of carrying one or more human occupants and is powered by any form of energy. The term “vehicle” is a motor 5 vehicle which includes, but is not limited to: cars, trucks, vans, minivans, and SUVs.
[0042] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, 10 the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/device of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.

We claim:
1. A torque based engine management system (200) for managing torque demand of convention alternator (202) and controlling idle speed of an internal combustion engine, the torque based engine management system (200) comprising: 5
an excitation current estimation module (203) for calculating excitation current based on electrical load ON/OFF signals (304);
an alternator rotation speed estimation module (204) for calculating rotation speed of alternator (201) based on the engine speed signal and alternator pulley ratio (502); and 10
an alternator control system (208) coupled with the excitation current estimation module (203) and the alternator rotation speed estimation module (204) for calculating alternator torque demand (209) based on the calculated excitation current (402) and calculated alternator rotation speed (503). 15
2. The torque based engine management system (200) as claimed in claim 1, wherein the excitation current estimation module (203, 400) calculates the base excitation current values (9, 10, 11) based on electrical loads input ON/OFF signals (6,7,8) by switching ON/OFF corresponding to electrical 20 loads (3, 4, 5) one by one.
3. The torque based engine management system (200) as claimed in claim 1, wherein the excitation current estimation module (203, 400) calculates initial excess current when an electrical load is switched ON, wherein 25 calculation of the initial excess current comprises steps of :
calculating initial excess current required by the electrical load when the electrical load is switched ON;
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calculating duration for which electric load demand for initial excess current; and
calculating rate at which initial excess current is to be changed after the initial demand duration is over.
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4. The torque based engine management system (200) as claimed in claim 2 and 3, wherein the excitation current estimation module (203, 400) calculates excitation current value by adding base excitation current value with the initial excess excitation current.
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5. The torque based engine management system (200) as claimed in claim 3, wherein the excitation current estimation module (203, 400) calculates the excitation current experimentally for each electrical load (3, 4, 5).
6. The torque based engine management system (200) as claimed in claim 1, 15 wherein the alternator rotation speed estimation module (204) calculates the alternator speed value (503) by multiplying the engine speed signal (504) with pulley ratio (502) of the alternator pulley with the engine pulley.
7. The torque based engine management system (200) as claimed in claim 1, 20 wherein torque based engine management system (200) is configured in Electronic Control Unit (300).
8. A method for managing toque requirement of conventional alternator (202) of a vehicle, the method comprising: 25
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receiving (601), by an excitation current estimation module (203, 307) of Electronic Control Unit (ECU) (300), electrical load ON/OFF signals (304) from electrical load (301);
receiving (601), by an alternator rotation speed estimation module (204, 308) of the ECU (300), engine speed signals (305); 5
calculating (602), by an excitation current estimation module (203, 307) of the ECU (300), excitation current (206, 402) of electric load (301) based on the electrical load ON/OFF signals (304);
calculating (603), by an alternator rotation speed estimation module (204, 308) of the ECU (300), alternator rotation speed (503) based on the 10 received engine speed signals (305);
calculating (604), by an alternator control system (208, 310) of the ECU (300), alternator torque requirement based on the calculated excitation current value (402) and the calculated alternator speed value (503);
sending the calculated alternator torque requirement to torque 15 management system for sending the calculated demanded alternator torque to engine (313).
9. The method as claimed in claim 8, wherein the excitation current estimation module (203, 400) calculates initial excess current when an electrical load is 20 switched ON, wherein calculation of the initial excess current comprises steps of :
calculating initial excess current required by the electrical load when the electrical load is switched ON;
calculating duration for which electric load demand for initial excess 25 current; and
calculating rate at which initial excess current is to be changed after the initial demand duration is over.
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10. The method as claimed in claim 8, wherein the alternator rotation speed estimation module (204) calculates the alternator speed value (503) by multiplying the engine speed signal (504) with pulley ratio (502) of the alternator pulley with the engine pulley.