WO2018116144A1

WO2018116144A1 - Control system for a vehicle and a control method thereof

Info

Publication number: WO2018116144A1
Application number: PCT/IB2017/058095
Authority: WO
Inventors: Krishnamohan GEDDADI; Surajit Das; Samraj JABEZ DHINAGAR
Original assignee: Tvs Motor Company Limited
Priority date: 2016-12-19
Filing date: 2017-12-19
Publication date: 2018-06-28
Also published as: TW201823068A

Abstract

The present invention discloses a control system (100) for a vehicle for regulating magnitude of current, including duration of current, supplied to a traction motor (104) of the vehicle. The magnitude of current is regulated based on vehicle based information including temperature of components (101, 102, 103, 104) of the control system (100), vehicle speed and throttle input.

Description

CONTROL SYSTEM FOR A VEHICLE AND A CONTROL METHOD

THEREOF

Technical Field

[1 ] The present subject matter described herein generally relates to a control system for a vehicle and particularly but not exclusively relates to a control system for regulating current delivered to a traction motor of said vehicle.

Background

[2] In recent times there is an increased demand to control emissions from automobiles, in view of stringent emission norms. As a result, a number of hybrid and electric vehicles (hereinafter EV) are seeing the light of the day in order to minimize the amount of emissions.

[3] For example, typical hybrid vehicles configured to be powered either by an internal combustion engine or a traction motor or both, are replacing normal engine powered vehicles. Said hybrid vehicles are configured to operate in different operating modes such as sole engine mode, sole traction motor mode, hybrid power mode, hybrid economy mode and the like. Further, said hybrid vehicles also include a battery to power the traction motor and an electronic control unit to control the input power supplied to the traction motor. Typically, said hybrid vehicles are configured to operate in sole traction motor mode/EVmode as a default drive mode during vehicle starting conditions. Therefore, in order to provide good initial acceleration for the vehicle at zero speed, it is required that the battery, the traction motor and the electronic control unit should work together for supply of high power. In other words, it is required that short time high current be supplied to the traction motor in order to achieve high initial acceleration. However, supply of short time high current through the traction motor results in damage to the traction motor winding due to the sudden rise in temperature of traction motor. Therefore, most manufacturers fail to use the full capacity of traction motor even though the traction motor may have good short time current capacity. [4] There is therefore a need to control passage of short time high current through the traction motor so as to prevent damage to the traction motor winding, while ensuring that the initial acceleration of the hybrid/electric vehicle is not compromised.

[5] Known arts involve the use an additional temperature sensor for monitoring temperature of the traction motor, and based on which additional current is pumped through the windings of the traction motor for providing initial acceleration. However, use of an additional temperature sensor leads to an increase in the overall cost of the traction motor. Further, some known arts conventionally use the electronic control unit to store temperature of traction motor related information which is used for controlling passage of current through the traction motor. However, the use of the electronic control unit for storing temperature of traction motor related information proves to be disadvantageous especially while restarting the vehicle, since the electronic control unit loses the previously stored information including temperature of traction motor related information when the vehicle is switched OFF intermittently. Therefore, the chances of passing high current through the traction motor without considering its previous temperature increase while restarting the vehicle is high, thereby increasing the chances of traction motor damage.

[6] It is therefore essential to address problems set out in the known prior arts.

Summary of the Invention

[7] The present invention has been made in view of the above circumstances.

[8] It is an object of the present invention to provide a control system for a vehicle for regulating magnitude of current supplied to a traction motor of the vehicle.

[9] It is another object of the present invention to provide a control system for a vehicle for regulating the duration for which high current may be supplied to the traction motor of the vehicle. [10] It is yet another object of the present invention to provide a control system for a vehicle capable of estimating temperature of traction motor without the use of additional temperature of traction motor sensor or a thermocouple.

[11 ] It is one more object of the present invention to provide a control system for a vehicle which includes a battery having a battery management system capable of storing estimated temperature of traction motor as calculated by an electronic control unit before vehicle ignition is switched OFF.

[12] It is still another object of the present invention to provide a control system including a battery management system capable of calculating temperature of traction motor to be achieved for vehicle restart condition.

[13] Accordingly, with the above and other objects in view, the present invention provides a control system for regulating passage of current l_max through a traction motor thereof based on estimated temperature of traction motor not only for initial acceleration conditions, but also for vehicle running and vehicle restart conditions. The control system as per the present invention includes a plurality of sensors disposed on one or more locations of the vehicle, a battery unit having a battery management system, an electronic control unit communicatively connected to said battery management system, a power controller communicatively connected to the electronic control unit and a traction motor operatively connected to the power controller.

[14] As per an aspect of the present invention, the electronic control unit is configured to calculate a requisite pulse duration T_PulseDuration for which high current lm_ax can be passed through said traction motor. The magnitude or value of lm_ax is greater than a predetermined value. Particularly, said electronic control unit calculates said requisite pulse duration T_PulseDuration based on a pulse duration limit estimated for each component of the control system including that of the battery unit, the electronic control unit, the power controller and the traction motor, said pulse duration limit for each component in turn being estimated based on the estimated temperature of each component. In the present embodiment, while the temperature of traction motor is estimated by the electronic control unit based on phase current of said traction motor, said phase current being calculated from DC bus current thereof, the temperature of battery unit is arrived at using temperature senor provided within said battery unit. Further, the pulse duration limit for the electronic control unit is also calculated based on temperature of the electronic control unit. Once the pulse duration limit is calculated for each component, the electronic control unit estimates the requisite pulse duration T_PulseDuration to initiate a trigger signal to be sent to the power controller, which on receiving said trigger signal enables passage of Imax- The T_PulseDuration is arrived at by comparing the pulse duration limit for each component and chooses a minimum pulse duration limit value corresponding to any one of said components as the requisite pulse duration T_PulseDuration. Besides estimating the requisite pulse duration T_PulseDuration for which may be passed by the power controller, the electronic control unit also estimates the conditions under which current I_max can be sent to the traction motor by the power controller. For example, when the rate of rise of throttle input is greater than a threshold throttle input value and measured vehicle speed is lesser than threshold vehicle speed, the electronic control unit sends a trigger signal to the power controller which allows passage of current Imax for the requisite pulse duration T_PulseDuration. In other words, whenever there is a demand for higher acceleration, the power controller allows the passage of current Imax for the requisite pulse duration T_PulseDuration. However, in conditions where the vehicle speed exceeds threshold vehicle speed or when a measured duration for which current I_ms circulated exceeds requisite pulse duration T_PulseDuration, the power controller restricts the passage of current I_max and causes passage of a reference current I_nom through the traction motor. I_nom is a nominal current. The magnitude of I_nom is lesser than the magnitude of I_max. The plurality of sensors is adapted to transmit at least one data signal to the electronic control unit. Said at least one data signal includes one or more of temperature of the battery unit, temperature of the electronic control unit, temperature of the power controller, temperature of the traction motor, throttle input, and vehicle speed.

[15] As per another aspect of the present invention, the control system is configured to store estimated temperature of traction motor at the instant when the ignition switch is turned OFF and further estimate reduction in temperature of traction motor to be achieved, so as to enable passage of current I_max for the corresponding requisite pulse duration T_PulseDuration through the traction motor during vehicle restart conditions, so that the traction motor is not damaged due to sudden passage of current I_ms even when the traction motor is still hot. Particularly, in the present invention, the Battery Management System of the battery unit is configured to receive and store the estimated temperature of traction motor at the instant when the ignition switch is turned OFF and further configured to estimate reduction in temperature of traction motor to be achieved, so as to enable passage of current 1^ for the requisite pulse duration T_PulseDuration through the traction motor during vehicle restart conditions.

[16] Thus, the control system as per the present invention aids in regulating passage of current I_max through the traction motor taking into consideration various parameters including temperature of traction motor, and temperature of battery unit, and thus enables in ensuring that there is minimal damage to the traction motor, while at the same time ensuring that sufficient high current is pumped through the traction motor for achieving high acceleration whenever there is a demand for the same. The present invention also serves as a cost effective means since it neither involves the use of a temperature sensor nor a thermocouple for estimating temperature of traction motor.

[17] Further, the present invention also describes a method of operation of said control system for regulating passage of current Imax through the traction motor.

[18] Summary provided above explains the basic features of the invention and does not limit the scope of the invention. The nature and further characteristic features of the present invention will be made clearer from the following descriptions made with reference to the accompanying drawings.

Brief Description of Drawings

[19] The above and other features, aspects, and advantages of the subject matter will be better understood with regard to the following description and accompanying drawings where: [20] FIG.l is a schematic representation of a vehicle in accordance with an embodiment of the present invention.

[21 ] FIG.2 is a schematic representation of a control system in accordance with an embodiment of the present invention.

[22] FIG.3 illustrates a flowchart depicting steps of a method of functioning of an electronic control unit of the control system during vehicle starting and vehicle running conditions.

[23] FIG.4 illustrates a flowchart depicting steps of a method of functioning of the electronic control unit during ignition switch OFF condition.

[24] FIG.5 illustrates a flowchart depicting steps of a method of operation of the battery management system of the control system during ignition switch OFF condition.

[25] FIG.6 illustrates a flowchart for depicting steps of method of operation of the electronic control unit for regulating current I_max during vehicle restart conditions.

Detailed Description

[26] The present subject matter described herein relates to a control system for a vehicle which serves to regulate current 1^ passing through a traction motor of said control system. Particularly, said control system serves to estimate a requisite pulse duration T_PulseDuration for which current Imax may be passed through the traction motor, without leading to damage of the traction motor due to high temperature.

[27] Exemplary embodiments detailing features of the control system, in accordance with the present invention will be described hereunder. The embodiments described herein apply to a vehicle powered by two or more power sources including an internal combustion engine, the traction motor and a battery unit. However, the present invention is not restricted in its application and is also applicable to vehicles employing only the traction motor and the battery unit, say for example an electric vehicle. Further, although the present invention has been exemplified for a two-wheeled vehicle, application of the present invention need not be restricted to a two-wheeled vehicle, and maybe applied to any vehicle including a three-wheeled vehicle and a four-wheeled vehicle.

[28] The present invention has been exemplified for a hybrid vehicle as illustrated in FIG.l.

[29] With reference to FIG.l, a description is made of a hybrid two-wheeled vehicle, hereinafter D vehicleD 10 in accordance with an embodiment of the present invention. FIG.l is a side view of said vehicle 10. Said vehicle 10 illustrated, has a step-through type frame assembly 15. The step-through type frame assembly 15 includes a head tube 15A, a main tube 15B and a pair of side tubes 15C. Particularly, the main tube 15B extends downwards from a rear portion of the head tube 15A and then extends rearwards in an inclined manner. Further, the pair of side tubes 15C extends rearwardly from the main tube 15B. Thus, the frame assembly 15 extends from a front portion F to rear a rear portion R of the vehicle.

[30] Said vehicle 10 further includes a plurality of body panels for covering the frame assembly 15, and is mounted thereto. In the present embodiment said plurality of body panels includes a front panel 15FP, a leg shield 15LS, an under-seat cover 15SC, and a left and a right side panel 15SP. Further, a glove box may be mounted to said leg shield 15LS.

[31 ] In a step through space formed between said leg shield 15LS and said under seat cover 15SC, a floorboard 12 is provided. Further, a seat assembly 25 is disposed above said under-seat cover 15SC, and is mounted to the pair of side tubes 15C. A utility box (not shown) is disposed below the seat assembly 25. A fuel tank (not shown) is positioned below the utility box. A rear fender 26 for covering at least a portion of a rear wheel 27 is positioned below the fuel tank.

[32] One or more suspension(s)/shock absorbers 30 are provided in a rear portion of said vehicle 10 for comfortable ride. Further said vehicle 10 comprises of plurality of electrical and electronic components including a headlight 35A, a taillight 35B, a transistor controlled ignition (TCI) unit (not shown), a starter traction motor (not shown) and the like. A touch screen LCD unit in the form of an instrument display panel (not shown) is provided on a handle bar 11 to display various operating drive modes, power flow pattern and warning signals. Rear view mirrors 13 are mounted on the right and left sides of the handle bar 11. Said vehicle 10 is also provided with hazard lamps (not shown).

[33] An internal combustion engine 14, hereinafter D engineD , is arranged behind said floorboard 12 and supported between the pair of side tubes 15C. Particularly, said engine 14 is supported by a swing arm 19. The swing arm 19 is attached to a lower portion of the main tube 15B by means of a toggle link (not shown). The other end of the swing arm 19 holds the rear wheel 27. The rear wheel 27 and the swing arm 19 are connected to the pair of side frames 15C by means of a pair of shock absorbers 30 provided on either side of the vehicle.

[34] Said hybrid vehicle 10 further includes a traction motor 103 (shown in FIG.2) mounted on a hub of the rear wheel 27. In the present embodiment, said traction motor 103 (shown in FIG.2) is a Brushless Direct Current (hereinafter BLDC) traction motor. Further, said traction motor 103 is powered by a battery unit 102 (shown in FIG.2) disposed in a rear portion of the vehicle. An electronic control unit 101 (shown in FIG.2) is also provided to control various vehicle operative modes, such as sole engine mode, sole traction motor mode and hybrid power mode, based on the source of power being, respectively, the engine 14, the battery unit 102 transmitted to the traction motor 103 and both. Said electronic control unit 101, said power controller 104, said plurality of sensors 105, said battery unit 102 and said traction motor 103 constitute parts of a control system 100 of said hybrid vehicle 10. The plurality of sensors 105 may include a first set of sensors to measure temperature of battery unit 102, cell voltage, battery current, SOC. The plurality of sensors 105 may also include a second set of sensors to measure temperature of power controller 104 and temperature of electronic control unit 101. The plurality of sensors 105 can further include sensors to measure throttle slope, a vehicle speed sensor, and the like.

[35] The hybrid vehicle 10 is configured to be propelled either by the engine 14 alone or by said traction motor 103 alone or by both engine 14 and said traction motor 103 simultaneously. At zero vehicle speed, a rider can select any of the following four operating drive modes with the help of a mode switch (not shown). The four operating drive modes of the hybrid vehicle 10 are: (a) a sole engine mode where engine 14 alone powers the vehicle (b) a sole traction motor mode where the traction motor 103 alone powers the vehicle (c) a hybrid power mode wherein the engine 14 and the traction motor 103 together power the vehicle (d) a hybrid economy mode wherein only the engine 14 or only the traction motor 103 or both power the hybrid vehicle depending on the vehicle operating conditions. The vehicle operating conditions includes the vehicle speed and vehicle rpm.

[36] In other words, the rear wheel 27 of the vehicle is driven by either the engine 14 alone or by the traction motor 103 alone or by both the engine 14 and the traction motor 103 simultaneously. Particularly, power from the engine 14 to the rear wheel 27 is transmitted by a transmission assembly including a drive system (not shown) as per an embodiment of the present invention. However, when the traction motor 103 drives, power from the traction motor 103 is directly transmitted to the rear wheel 27. In the present embodiment, said traction motor 103 is covered by a traction motor shroud from at least one side. As per an aspect of the present invention, said traction motor shroud serves to at least partially encompass/house one or more parts of the drive system and therefore constitutes a part of the drive system. On another side of the wheel shaft, the traction motor shroud serves to house a brake drum (not shown).

[37] Said vehicle 10 as described above includes the control system 100 as shown in FIG.2. As seen in FIG.2, said control system 100 includes the electronic control unit 101, the plurality of sensors 105 is adapted to transmit at least one data signal to the electronic control unit 101 the power controller 104 communicatively connected to the electronic control unit 101, the battery unit 102 communicatively connected to said electronic control unit 101 and said traction motor 103 operatively connected to said power controller 104. In the present embodiment, said electronic control unit 101 is powered by said battery unit 102, said battery unit 102 having its own control unit called battery management system, hereinafter D BMSD . The BMS as per the present embodiment receives and sends signals from and to the electronic control unit 101. Particularly, in the present embodiment, said BMS is configured to communicate with said electronic control unit 101, information relating to battery parameters including temperature of battery unit 102. In the present embodiment, temperature of battery unit 102 is calculated using temperature sensors, from the plurality of sensors 105, provided in said battery unit 102. Further, based on the temperature of the battery unit 102 and other battery parameters such as cell voltage, battery current, SOC, and the like, which are detected by one or more of the plurality of sensors 105, the BMS estimates a battery unit 102 based pulse duration limit t3 for which current I_max can be supplied to the traction motor 103. The estimated t3 is transmitted to the electronic control unit 101.

[38] In the present embodiment, said electronic control unit 101 is also configured to estimate its own temperature based on inputs provided by the set of temperature sensors, of the plurality of sensors 105, regarding heat sink temperature. In the present embodiment, for estimation of temperature of the traction motor 103, the traction motor 103 is neither provided with an independent temperature sensor nor a thermocouple. However, the electronic control unit 101 is configured to estimate the temperature of traction motor 103. Particularly, as per an aspect of the present invention, the electronic control unit 101 is configured to calculate the estimated temperature of traction motor 103 using phase current of the traction motor 103. The phase current is calculated using DC bus current of the traction motor 103 with the aid of standard formulae stored in said electronic control unit 101 for calculation of the same.

[39] As per an aspect of the present invention, said control system 100 is configured to regulate current I_max through the traction motor 103 during vehicle starting and vehicle running conditions based on the estimated temperature of traction motor 103 calculated. Further, the control system 100 as per another aspect of the present invention is also configured to regulate current I_max passed through the traction motor 103 when the vehicle is restarted after intermittently switching OFF the ignition. Particularly, said control system 100 regulates the current I_max passed through the traction motor 103 by controlling time interval for which current Imax is passed through the traction motor 103. Steps involved in the regulation of current I_max through the traction motor 103 is elaborated in the following paragraphs and are supported with corresponding flowcharts. [40] FIG.3 illustrates steps of working of the electronic control unit 101 during vehicle starting conditions, especially for providing high initial acceleration to the vehicle. Particularly, flowchart 200 in FIG.3 denotes the steps of operation of the electronic control unit 101 for regulating current I_ms through the traction motor 103 during vehicle starting conditions and during vehicle running conditions.

[41 ] In a first step of its operation at block 201, the electronic control unit 101 causes the vehicle to start in an EV mode/electric mode and passes a trigger signal to the power controller 104 which allows passage of current I_max through the traction motor 103 for providing high initial acceleration for the vehicle. However, the power controller 104 allows the passage of current I_ms through the traction motor 103 only for a certain duration in order to prevent damage to windings of the traction motor 103. Particularly, said electronic control unit 101 arrives at a requisite pulse duration T_PulseDuration for passage of I_max by performing the steps from block 202-207. For example, in the present embodiment, the electronic control unit 101 continuously/dynamically monitors a throttle input, said throttle input being provided by at least one of the plurality of sensors 105. The electronic control unit 101 calculates slope of throttle input, which is rate of rise of throttle, dtps_dt at block 202. The electronic control unit 101 further estimates temperature of traction motor 103 by firstly estimating phase current of the traction motor at block 203, with said phase current in turn being estimated using DC bus current. Further, the electronic control unit 101 estimates temperature of the traction motor 103 based pulse duration limit tl , temperature of electronic control unit 101 based pulse duration limit t9 and temperature of the power controller 104 based pulse duration limit t2 at blocks 204, 205 respectively. Further the electronic control unit 101 receives CAN communication regarding temperature of battery unit 102 based pulse duration limit t3 at block 206. In the present embodiment, while the electronic control unit 101 estimates tl, t9 and t2 based on the respective temperature of traction motor 103 temperature of the electronic control unit 101 and temperature of power controller 104 calculated by the electronic control unit 101; t3 as read by the BMS and communicated to the electronic control unit 101 is directly processed by the electronic control unit 101. Following the estimation of tl, t9, t2 and t3, the electronic control unit 101 arrives at the requisite pulse duration T_PulseDuration value by choosing a minimum pulse duration limit value from the estimated the pulse duration limit values tl, t9, t2 and t3, at block 207. By selecting the minimum pulse duration limit value from the estimated pulse duration limit values as the requisite pulse duration T_PulseDuration, it is ensured that the duration for which current I_max is passed through the traction motor 103 is limited taking into consideration the temperature of the traction motor 103, of the battery unit 102 and that of the electronic control unit 101 itself, and thereby taking care to ensure that none of the components of the control system 100 are subjected to damage due to passage of high current.

[42] After arriving at the requisite pulse duration T_PulseDuration for the passage of current I_max at block 207, the electronic control unit 101 also checks whether the conditions at which vehicle is being ridden demands the passage of current I_max. For example, at block 208 the electronic control unit 101 checks whether a measured slope of throttle input, which is rate of rise of throttle, dtps_dt is greater than a threshold slope of throttle input or threshold input value of rate of rise of throttle, dtps_dt_TH. If the measured rate of rise of throttle dtps_dt is greater than a threshold input value of rate of rise of throttle dtps_dt_TH the electronic control unit 101 further checks for vehicle speed at block 209. If a measured vehicle speed is less than a threshold vehicle speed, then electronic control unit 101 sends a trigger signal to the power controller 104 which allows passage of current I_max. In other words, whenever there is a need for more power, especially when the rider is giving throttle at low vehicle speed, the electronic control unit 101 sends a trigger signal to the power controller 104 which dynamically allows passage of current I_max through the traction motor 103 for requisite duration T_PulseDuration at block 210, said T_PulseDuration being calculated as per the steps from 204-207. The throttle value, vehicle speed and temperature of each component of the control system 100 are received by the electronic control unit 101 from the plurality of sensors 105.

[43] Further, at block 211 the electronic control unit 101 also checks if measured duration for which I_max is circulated through the traction motor 103 has exceeded the requisite pulse duration T_PulseDuration. If the measured duration (in seconds) exceeds the requisite T_PulseDuration then the electronic control unit 101 sends a trigger signal to the power controller 104 which stops the passage of current I_max and causes passage of nominal current, I_nor¾ through the traction motor 103 at block 212. However, if the measured duration for which current passed through the traction motor 103 has not exceeded the requisite pulse duration T_PulseDuration, then the electronic control unit 101 checks for the measured vehicle speed at block 213. If the measured vehicle speed is greater than the threshold vehicle speed, then the electronic control unit 101 sends a trigger signal to the power controller 104 which allows nominal current to be passed through the traction motor 103 rather than current I_ms. Thus, the control system 100 as per the present invention, aids in regulating the passage of current Ι through the traction motor 103 under different riding conditions while taking into account temperature of the traction motor 103, temperature of the battery unit 102, the temperature of the power controller 104 and that of the electronic control unit 101 simultaneously.

[44] Further, as per another aspect of the present invention, the control system 100 is also configured to communicate and store the estimated temperature of traction motor 103 for use during vehicle restart conditions. Particularly, said electronic control unit 101 of the control system 100 is configured to communicate the estimated temperature of traction motor 103 to the BMS of the battery unit 102 under certain conditions. The flowchart 300 in FIG.4 denotes the steps of working of the electronic control unit 101 in communicating the estimated temperature of traction motor 103 as calculated by it to the BMS of the battery unit 102. For example, as may be seen in FIG.4, in a running condition of the vehicle, the electronic control unit 101 dynamically calculates the estimated temperature of traction motor 103 as described in the preceding paragraphs. At block 301, the electronic control unit 101 checks whether the Ignition is switched ON, and in a condition where the Ignition switch is switched OFF, the electronic control unit 101 immediately communicates via Controller Area Network (hereinafter CAN) communication the estimated temperature of traction motor 103 to the BMS of the battery unit 102 at block 302 which is capable of storing said estimated temperature of the traction motor 103 for further use during vehicle restarting conditions. In all other conditions, the electronic control unit 101 continues to calculate the estimated temperature of the traction motor 103 and the corresponding requisite pulse duration T_PulseDuration.

[45] As per one more aspect of the present invention, the control system 100 is also configured to calculate the estimated temperature of traction motor 103 for vehicle restart condition. Flowchart 400 denoted in FIG.5 denotes the steps involved in the working of the BMS of the battery unit 102. In a condition where the ignition switch of the vehicle is switched OFF and where the BMS of the battery unit 102 receives the estimated temperature of traction motor 103 previously calculated and communicated by the electronic control unit 101, the BMS at block 401 of the flowchart checks whether the estimated temperature of traction motor 103 received is greater than a predetermined threshold temperature. If the estimated temperature of traction motor 103 received is greater than the predetermined threshold temperature, the BMS estimates a reduction in temperature to be achieved for the traction motor 103 at block 402, so that when the ignition switch of the vehicle is turned ON after being intermittently switched OFF, said reduction in temperature to be achieved is communicated to the electronic control unit 101 at block 403. The electronic control unit 101 on receiving communication regarding the reduction in temperature to be achieved for the traction motor 103 calculates the requisite restart pulse duration T_RestartPulseDuration for which current I_max may be passed through the traction motor 103.

[46] For example, FIG.6 illustrates a flowchart 500 depicting a method of operation of the electronic control unit 101 for regulating passage of current I_max during vehicle restart conditions. Once the ignition switch is turned ON after being intermittently switched OFF, the vehicle is restarted in the EV mode by the electronic control unit 101. Further, once the vehicle is restarted, the electronic control unit 101 receives input regarding the reduction in temperature to be achieved for the traction motor 103 from the BMS at block 501. Further, based on the input received regarding the reduction in temperature to be achieved, the electronic control unit 101 estimates temperature of traction motor 103 based restart pulse duration tlR at block 502. The electronic control unit 101 also estimates the temperature of the power controller 104 based restart pulse duration limit t2R and temperature of the electronic control unit 101 based restart pulse duration limit t9R and processes the temperature of battery unit 102 based restart pulse duration limit t3R received from the BMS at blocks 503 and 504 respectively. Furthermore, the electronic control unit 101 calculates requisite restart pulse duration T_PulseDuration by choosing a minimum restart pulse duration limit value from the estimated restart pulse duration limit values tlR, t9R, t2R and t3R, at block 505. Thereafter, at block 506 the power controller 104 allows passage of current l_max on receiving the trigger signal from the electronic control unit 101 for the requisite restart pulse duration T_PulseDuration through the traction motor 103, thereby ensuring that flow of current I_max through the traction motor 103 is limited while the traction motor 103 is still hot during vehicle restart conditions.

[47] As is apparent from the present teaching, the control system as per the present invention aids in regulating passage of current through the traction motor in all conditions including vehicle starting and restarting conditions without compromising on initial acceleration provided to the vehicle, taking into consideration different parameters such as temperature of traction motor and temperature of battery unit without involving the use of additional temperature sensors or thermocouples for estimating temperature of traction motor.

Claims

We claim:

1. A control system (100) for a vehicle, said control system (100) comprising a battery management system including a battery unit (102), an electronic control unit (101) communicatively connected to said battery management system, a power controller

(104) communicatively connected to the electronic control unit (101), a traction motor (103) operatively connected to the power controller (104) and a plurality of sensors

(105) communicatively connected to the electronic control unit (101), said plurality of sensors (105) being disposed on one or more locations on the vehicle, wherein the electronic control unit (101) is adapted to receive at least one data signal from said plurality of sensors (105), the electronic control unit (101) is configured to calculate a T_PulseDuration based on said at least one data signal, said T_PulseDuration being a requisite pulse duration for allowing passage of l_max, and I_max being a magnitude of current greater than a predetermined value.

2. The control system (100) as claimed in claim 1, wherein said at least one data signal includes one or more of temperature of the battery unit (102), temperature of the electronic control unit (101), temperature of the power controller (104), temperature of the traction motor (103), throttle input, and vehicle speed.

3. The control system (100) as claimed in claim 1 or claim 2, wherein the temperature of the traction motor (103) is estimated by the electronic control unit (101) based on phase current of the traction motor (103), and wherein the phase current of the traction motor (103) is calculated from DC bus current of the traction motor (103).

4. The control system (100) as claimed in claim 1 or claim 2, wherein the temperature of the battery is measured by a temperature sensor of said plurality of sensors (105), said temperature sensor being disposed within the battery unit (102), and wherein the pulse duration estimation limit for the battery unit (102) is measured by the battery management system.

5. The control system (100) as claimed in claim 1, wherein the electronic control unit (101) transmits a trigger signal based on said T_PulseDuration to said power controller (104), wherein said power controller (104) on receiving the trigger signal allows flow of the I_max to the traction motor (103), said I_max being allowed to flow for the requisite pulse duration defined by said T_PulseDuration.

6. The control system (100) as claimed in claim 1 or claim 5, wherein the T_PulseDuration is a minimum pulse duration limit value of a set of values recorded for pulse duration limit estimation for each of the battery unit (102), the electronic control unit (101), the power controller (104) and the traction motor (103) of the control system (100).

7. The control system (100) as claimed in claim 1 or claim 5, wherein the flow of I_max is allowed by the power controller (104) on satisfaction of at least one event of a set of events, said set of events including an event of rate of rise of throttle being greater than a threshold input value of rate of rise of throttle and an event of a measured vehicle speed being lesser than a threshold vehicle speed.

8. The control system (100) as claimed in claim 1 or claim 5, wherein the power controller (104) passes a reference current I_nom in the event of the measured vehicle speed being greater than the threshold vehicle speed, the reference current I_nom being a nominal current.

9. The control system (100) as claimed in claim 1 or claim 2, wherein the battery management system is configured to store an estimated temperature of the traction motor (103) at an instant of turning off an ignition switch.

10. The control system (100) as claimed in claim 1 or claim 9, wherein the battery management system is operable to estimate reduction of the estimated temperature of the traction motor (103) to be achieved, wherein said reduction of the estimated temperature of the traction motor (103) is calculated in an event of the value of the estimated temperature of the traction motor (103) at the instant of turning off an ignition switch being greater than a predetermined threshold temperature.

11. The control system (100) as claimed in claim 1, wherein the T_PulseDuration is based on pulse duration limit estimation for the battery unit (102), the electronic control unit (101), the power controller (104) and the traction motor (103).

12. The control system (100) as claimed in claim 1 or claim 11, wherein the pulse duration limit estimation for each of the battery unit (102), the electronic control unit

(101) , the power controller (104) and the traction motor (103) is based on said at least one data signal from the plurality of sensors (105).

13. A control method to regulate passage of I_max through a traction motor (103) of a vehicle, wherein said I_max being a magnitude of current greater than a predetermined value, and wherein said control method comprises steps of:

allowing initial passage of said I_max through the traction motor (103) for a predetermined duration, wherein said initial passage of said I_max is on starting of said vehicle;

sensing at least one data by a plurality of sensors (105) disposed on one or more locations on the vehicle, wherein said plurality of sensors (105) are communicatively connected to an electronic control unit (101);

receiving of said at least one data by the electronic control unit (101), estimating pulse duration limit for each of a battery unit (102), the electronic control unit (101), a power controller (104) and the traction motor (103) based on said at least one data signal from the plurality of sensors (105), wherein said at least one data signal includes temperature of the battery unit (102), temperature of the electronic control unit (101), temperature of the power controller (104), temperature of the traction motor (103), throttle input, and vehicle speed;

calculating a T_PulseDuration by the electronic control unit (101), said T_PulseDuration being a requisite pulse duration for allowing passage of I_max, wherein the T_PulseDuration is a minimum pulse duration limit value of a set of values recorded for the pulse duration limit estimated for each of the battery unit

(102) , the electronic control unit (101), the power controller (104) and the traction motor (103);

sending a trigger signal by the electronic control unit (101) to the power controller (104), said trigger signal being based on said T_PulseDuration;

allowing passage of a current by the power controller (104) on receiving said trigger signal from the electronic control unit (101), the current being passed to the traction motor (103), the magnitude of the current being calculated based on satisfaction of a set of events, wherein the magnitude of the current is I_nom in the event of the measured vehicle speed being greater than a threshold vehicle speed, said I_nom being a nominal current, and wherein the magnitude of the current is said I_max in the event of the measured vehicle speed being lesser than a threshold value, and wherein the a measured duration of passage of said Imax is lesser than said T_PulseDuration, said T_PulseDuration being a requisite pulse duration for allowing passage of said Imax, and wherein the magnitude of the current is reduced to said I_nom in the event of the duration of passage of I_max is greater than said T_PulseDuration, wherein magnitude of said 1^ is greater than the magnitude of said I_n0m,-

14. The control method as claimed in claim 13, wherein said at least one data signal includes the temperature of the traction motor (103), said temperature of the traction motor (103) being estimated by estimating DC bus current and estimating phase current of the traction motor (103).

15. The control method as claimed in claim 13, wherein said at least one data signal includes the temperature of the battery unit (102), wherein the pulse duration limit based on the temperature of the battery unit (102) is transmitted to the electronic control unit (101) through CAN communication.

16. The control method as claimed in claim 13, wherein said set of events, in the step of allowing passage of the current to the traction motor (103), includes an event of a measured rate of rise of throttle being greater than a threshold input value of rate of rise of throttle, wherein the magnitude of the current is I_max in the event of the measured rate of rise of throttle being greater than said threshold input value of rate of rise of throttle.

17. The control method as claimed in claim 13, wherein the step of calculating the T_PulseDuration includes calculating a T_RestartPulseDuration for which Imax is passed through the traction motor (103), said T_RestartPulseDuration being a requisite restart pulse duration, and wherein T_RestartPulseDuration is based on a reduction in temperature of the traction motor (103) to be achieved.

18. The control method as claimed in claim 13 or claim 17, wherein said reduction in the temperature of the traction motor (103) to be achieved is communicated by a battery management system to the electronic control unit (101), said battery management system being adapted to communicate in the event of the estimated temperature of the traction motor (103) being greater than a predetermined threshold temperature.