DESC:TECHNICAL FIELD
[0001] The present subject matter relates generally to internal combustion engines, and more particularly, but not exclusively, to an integrated starter generator for the internal combustion engine.
BACKGROUND
[0002] A starter motor and an electrical generator are separate components on most automobile with an internal combustion (IC) engine. An integrated starter generator (ISG) combines the functionalities of the starter motor and the generator into a single functional component. In a small IC engine, for example in the case of the IC engine of a motorcycle or a scooter type two-wheeler, the ISG is conventionally mounted on a crankshaft of the IC engine. Such ISG is also called a crankshaft starter generator (CSG). The CSG converts electric power from a battery into rotational power and rotates the crankshaft to start the engine and after the engine has started, the CSG converts mechanical energy due to rotation of the crankshaft into electrical energy in the form of electrical power that is supplied to a battery.
[0003] Typically, in such vehicles, the CSG has several advantages which make it a preferred device to be included. First, the CSG reduces vehicle weight by integrating the starter motor and the generator, and by eliminating components which are redundant to the generator and the starter motor. Second, the CSG achieves cost reduction because of the combined generator and starter motor cost less than the sum of the two devices individually. Moreover, administrative costs of vehicle manufacturers are also substantially reduced because only one part (CSG) instead of two (a generator and a starter motor) needs to be purchased, stored, made available as a service part, and so on. Third, the CSG also causes a reduction in assembly complexity. Fewer parts go into the CSG assembly often translating into lower assembly cost. Further, due to reduced number of parts and reduced assembly steps involved, the incidents or likelihood involving mistakes are also reduced.
[0004] More often than not, it is a continuous endeavor to extract optimum benefit from the ISG without increasing the cost and size of the IC engine. Additionally, high magnetic flux is required during engine starting but, during generation mode of operation and particularly at high rotor speeds, the high magnetic flux results in high core losses which deteriorates vehicle fuel economy.

BRIEF DESCRIPTION OF THE DRAWINGS
[0005] The detailed description of an ISG for an IC engine of the present subject matter is described with reference to the accompanying figures. Same numbers are used throughout the drawings to reference like features and components.
[0006] Fig. 1 illustrates an ISG control circuit that includes a three-phase BLDC motor, in accordance to an embodiment of the present subject matter.
[0007] Fig. 2 illustrates a graphical representation of excitation of at least two phases based on hall sensor signals, in accordance with an embodiment of the present subject matter.
[0008] Fig. 3 illustrates a conventional zero crossing detection circuit with only two interrupts for 360 degrees of electrical rotation.
[0009] Fig. 4 illustrates a charging current path during generation mode of the ISG control circuit as shown in Fig. 1, in accordance with an embodiment of the present subject matter.
[00010] Fig. 5 illustrates a firing angle control circuit, in accordance to an embodiment of the present subject matter.

DETAILED DESCRIPTION
[00011] Typically, three-phase brushless direct-current (BLDC) motors have been used as integrated starter generators (ISG). Such an ISG is an electrical machine, which is driven as a motor for cranking the IC engine of a vehicle, for example, a two-wheeled vehicle, and once the IC engine is running, the ISG is driven as a generator to supply power to the electrical loads in the vehicle. This is because the functions of cranking and generation are mutually exclusive in a vehicle. Such an ISG is generally mounted directly on the crankshaft of the vehicle. Further, several sensors, for instance, Hall-effect position sensors are disposed on the motor for commutation of the ISG while motoring. Such ISG machines are provided with one or more ISG controllers for assisting in motoring that consists of a three-phase inverter.
[00012] Typically, such three-phase inverters has input direct-current (DC) power supply from the battery. The three-phase inverter is also provided with switches that drive the appropriate phases of the ISG depending on the output received from the hall-effect position sensors. Generally, the selection of switches to be driven on the three-phase inverter is done by means of a microcontroller depending on the output of the three hall-effect position sensors.
[00013] Typically, such BLDC motors used as ISG have three inverter legs. Thus, there is a need to reduce the number of inverter legs from 3 to 2, which will enable cost reduction due to removal of high voltage MOSFETs, gate driver ICs and supporting passive components. Thus, the present subject matter provides a new control technique to excite a BLDC motor for start stop application.
[00014] The present subject matter provides a control technique that uses only two inverter legs to actuate three phase BLDC motor. During starting, the controller will check for the suitability of two out of the three phases for maximum torque output. Depending on the rotor position, the controller will choose the most appropriate two phases that can result in maximum torque output.
[00015] Further, initial excitation of two phases is based on the rotor position. After excitation, the controller will wait for a predetermined time to determine whether motor has reached the required acceleration level or not. If required acceleration is not reached, then the controller will try the other two combinations out of the available three excitation combinations, i.e., RB, RY, and BY.
[00016] For instance, if R, Y, B are three phases of the BLDC motor, and L1, L2 are two legs of the inverter. Initially R-L1, B-L2 will be connected via two SPDT relays (NC position). Further, in order to start the IC engine depending on rotor position, the controller will select two phases. For instance, if R and B phases of the BLDC motor are excited initially, and if the required acceleration is not achieved within a predetermined time, then R and Y phases will be excited by turning on relay 2. For example, turning on relay 2 will result in disconnection of B phase and connection to Y phase. Further, after second excitation, if the controller could not achieve enough acceleration within the predetermined time period, then B and Y phases will be excited by turning on relay 1. An example table showing three excitation states achieved with two inverter legs is shown below in Table 1.
State Inverter Leg-L1 Inverter Leg-L2 Relay 1 Relay 2
State 1 R B OFF OFF
State 2 R Y OFF ON
State 3 B Y ON ON
[Table 1]

[00017] In an implementation, the present subject matter provides an integrated starter generator (ISG) system for a two/three wheeled vehicle. In an embodiment, the ISG system of the present subject matter includes a three-phase electrical machine, for example, a three phase BLDC motor, which is mounted on a crankshaft of an internal combustion (IC) engine of the vehicle. The electrical machine is capable of motoring the IC engine until the engine is cranked. In an embodiment, the electrical machine is capable of generating electrical energy after the engine is cranked. In an implementation, one or more sensors are disposed at least on a stator surface of the electrical machine for detecting the rotational position of at least a rotor of the electrical machine.
[00018] Further, in one embodiment, an electronic controller, which is capable of controlling the motoring and generating of electrical energy by the electrical machine is provided. The electronic controller of the present subject matter includes a first inverter leg and a second inverter leg. The electronic controller activates at least a first combination of two phases of the three-phase electrical machine based at least on the rotational position of the rotor detected by the one or more sensors. Further, the first inverter leg and the second inverter leg are electronically coupled to a first relay and a second relay.
[00019] In one embodiment, the first relay and the second relay are turned ON/OFF to activate at least a second combination of two phases of the three-phase electrical machine based at least on a pre-determined acceleration level of the electrical machine. Further, the first relay and the second relay are turned OFF when the electrical machine exceeds the pre-determined acceleration level.
[00020] In one embodiment, the electrical machine of the ISG system of the present subject matter is a BLDC electric motor. In another embodiment, the electrical machine can be any other known electric motor that is capable of functioning similar to the BLDC motor. Further, in one embodiment, the one or more sensors are Hall-Effect position sensors.
[00021] In an embodiment, the three phase electrical machine of the ISGs system of the present subject matter includes a first motor phase R, a second motor phase B, and a third motor phase G. Similarly, in an embodiment, when the first relay and the second relay are in OFF condition, the first combination of two phases includes the first motor phase R coupled to the first inverter leg and the second motor phase B is coupled to the second inverter leg.
[00022] In an embodiment, when the first relay is in OFF condition, and the second relay is in ON condition, the second combination of two phases includes the first motor phase R coupled to the first inverter leg and the third motor phase G is coupled to the second inverter leg. Similarly, when the first relay and the second relay are in ON condition, a third combination of two phases includes the second motor phase B is coupled to the first inverter leg and the third motor phase G is coupled to the second inverter leg.
[00023] Fig. 1 illustrates an ISG control circuit 100 that includes a three-phase BLDC motor 112, in accordance to an embodiment of the present subject matter. In an embodiment, the BLDC motor 112 includes three phases, viz., Phase R 114, Phase B 116, and Phase Y 118 that are connected to an inverter bridge. In an embodiment, the inverter bridge includes at least two inverter legs, for example, inverter leg 1 L1, and inverter leg 2 L2. In an embodiment, the ISG control circuit 100 includes a first relay 106, a second relay 108, and a third relay 110. In an embodiment, when the first relay 106 and the second relay 108 are not switched ON, the motor phase R 114 will be connected to inverter leg 1 L1, while the motor phase B 116 will be connected to inverter leg 2 L2 respectively.
[00024] In an embodiment, when the IC engine (not shown) start switch is ON, the controller will select an appropriate state based on the inputs received from three Hall-effect sensors, viz., Hall sensor 1 H1, Hall sensor 2 H2, and Hall sensor 3 H3. For instance, based at least on the signal received from the three Hall sensors H1, H2, and H3, which determines the rotor (not shown) position of the BLDC motor 112, the controller selects appropriate phases for excitation. In an embodiment, the controller selects the appropriate phases for excitation based on lookup Table 2 shown below.
Hall sensor 1 (H1) Hall sensor 2 (H2) Hall sensor 3 (H3) Phases to be excited Hall input to be used for excitation CNTL_Relay 1 CNTL_Relay 2 State
0 0 1 Y, B H3 VBAT VBAT 3
0 1 0 R, Y H2 0 VBAT 2
0 1 1 R, B H1 0 0 1
1 0 0 R, B H1 0 0 1
1 0 1 R, Y H2 0 VBAT 2
1 1 0 Y, B H3 VBAT VBAT 3
[Table 2]
[00025] In an embodiment, Fig.1 depicts motoring mode or the cranking operation of the ISG control circuit 100. For instance, initially when the ignition is ON, the controller receives power and will be enabled. Subsequently, the controller will wait for the engine start switch input. Whenever, the controller receives engine start switch input, the controller will read input signals received from all Hall effect sensors H1, H2, and H3.
[00026] In an implementation, based on Table 2, the controller will determine at least two optimal phases out of the three phases (R, Y, B) of the BLDC motor 112, which can give maximum torque output for the corresponding rotor position of the motor 112. In an embodiment, after determining the at least two phases based on the lookup Table 2, the controller initiates controlling of relays Relay 1 106, and Relay 2 108 in order to connect the selected phases to inverter legs L1 and L2. For instance, after connecting the selected phases to inverter bridge, the controller proceeds to actuate Relay 3 110 in order to connect a battery 104 to the inverter bridge. For example, the controller transmits control signal CNTL_CONTACTOR = “VBAT” for connecting the battery 104 to the inverter bridge.
[00027] Further, based on the lookup Table 2, the controller will generate control signals L1_TOP_G 142, which is the control signal for top MOSFET M1 122 in inverter leg 1 L1. The actual Control signal generated from the controller is directly connected to gate driver IC and the output of the gate driver IC is connected to MOSFET M1 122 gate terminal. The controller also generates other control signals for the remaining three MOSFETS M2 124, M3, 126, and M4 128 respectively viz., L1_BOTTOM_G 144, L2_TOP_G 146, and L2_BOTTOM_G 148 in order to excite the selected at least two phases based at least on an input signal received from a single hall sensor H1, H2, or H3. After a predetermined time the controller will check the engine speed to determine whether the engine speed has reached minimum required cranking engine speed or not. For instance, if the engine is running above the minimum required speed, the controller will continue to excite the same two phases till engine starts or maximum cranking time reaches. However, for instance, if the engine speed is below the minimum required speed or at very low speed, the controller will stop exciting the selected phases and wait for a predetermined time in order to bring phase current to zero.
[00028] Let us consider an example, based on Table 2, when the input signals from Hall sensors H1, H2, and H3 are [0,1,1] or [1,0,0] respectively, phases R, and B will be excited by the Controller and the Hall-effect sensor H1 will be used for excitation, which will result in state 1. In this state 1, if motor output torque is sufficient to rotate the engine crankshaft, the controller will continue to excite phases R and B until engine starts. However, if the BLDC motor 112 is not able to rotate the crankshaft at the required speed within a predetermined time period in State 1, the controller will change the excitation to state 2.
[00029] In an implementation, in order to change from state 1 to state 2, the controller stops PWM for the L1 and L2 inverter legs and wait for a predefined time ‘t1’ to allow current to become zero. After the predetermined time ‘t1’, the controller turns ON Relay 2 108 and wait for a predefined time ‘t2’ (‘t1’ value is based on internal motor winding resistance and inductance, while ‘t2’ value is based on the relay closing time). Now the controller is configured to state 2, which ensures phases R that is connected to inverter leg L1, and phase Y that is connected to inverter leg L2 respectively is excited. In state 2, the controller will continue to excite R and Y phases, if motor output torque is sufficient to rotate the engine crankshaft until the engine starts. However, if the motor 112 is not able to rotate the crankshaft at required speed within a predetermined time period in the state 2, the controller will change the excitation to state 3.
[00030] In an embodiment, in order to change from state 2 to state 3, the controller stops PWM for the inverter leg L1 and inverter leg L2 and wait for a predefined time ‘t1’ to allow current to become zero. After the wait period, the controller turns ON Relay 1 106 and wait for a predefined time ‘t2’ (‘t1’ value is based on internal motor winding resistance and inductance, while ‘t2’ value is based on the relay closing time). In an embodiment, the Relay 2 108 is already in ON condition when the controller turns Relay 1 106 ON. Now the controller is configured to state 3, which ensures that the phase B connected to inverter leg L1, and phase Y connected to inverter leg L2 respectively is excited. In an implementation, in state 3, the controller will continue to excite phases B and Y, if motor output torque is sufficient to rotate the engine crankshaft until engine starts. However, if the motor 112 is not able to rotate the engine crankshaft at required speed within a predetermined time period, the controller will change the excitation to state 1 and the cycle repeats until the engine starts. Once the engine is started, the controller will stop transmitting PWM signal to L1 and L2 inverter legs and the controller de-energizes Relay 1 106 if the controller is in state 2 prior to starting or both Relay 1 106 & Relay 2 108 are de-energized, if the controller is in state 3 prior to starting. Thus, constant power consumption for the relay coils is eliminated. Once the engine is turned ON fully, the controller will change from motoring mode to generation mode.
[00031] In an embodiment, in order to select Phases R and Y, the controller generates control signals CNTL_Relay 1 = ‘0’, and CNTL_Relay 2 = ‘VBAT’, i.e., Phase R is connected to inverter leg L1, while Phase Y is connected to inverter leg L2. Similarly, in order to connect the battery 104 to the inverter bridge, the controller ensures that the control signal CNTL_CONTACTOR = ‘VBAT’, thereby actuating Relay 3 110. The controller generates the control signals L1_TOP_G 142, L1_BOTTOM_G 144, L2_TOP_G 146, and L2_BOTTOM_G 148 in order to excite phases R and Y based on Hall sensor signal H2. Now, if Hall signal H2 = 1, the control signal L2_TOP_G 146 and L1_BOTTOM_G 144 are turned ON. Similarly, when the Hall signal H2 = 0, the control signals L1_TOP_G 142 and L2_BOTTOM_G 148 are turned ON. At this juncture, the controller checks the engine speed. If the engine speed is higher than minimum engine speed required for cranking, the controller will continue to excite the phases R & Y till the engine starts or maximum cranking time limit is achieved.
[00032] In an embodiment, if the engine piston position prior to crank start is near to BDC (Bottom Dead Centre), then selected phases R & Y can create enough momentum to overcome the torque required at the TDC (Top Dead Centre) position and can run the engine at minimum required crank speed. However, if the engine piston position prior to crank start is near to TDC then selected phases R & Y may not be able to create enough momentum to overcome the torque required at TDC and resulting in complete stoppage of piston or move at very low speed. This is primarily due to the selected phases R & Y in that position cannot generate maximum torque output for the new rotor position. Hence a changeover is required from the selected phases R & Y to new set of phases, which can give maximum torque output according to the new rotor position. This changeover is considered only after a predetermined wait period to avoid multiple quick changeovers.
[00033] Fig. 2 illustrates a graphical representation 300 of excitation of at least two phases based on hall sensor signals, in accordance with an embodiment of the present subject matter. For instance, let us refer to VBR line voltage waveform 312 and hall sensor signal H1 314. When VBR voltage waveform 312 is positive hall signal H1=0, and when VBR voltage waveform 312 is negative, hall signal H1=1. That means when H1=1, voltage at inverter leg L1 is positive and it is negative at inverter leg L2. Similarly, referring to VRY line voltage waveform 310 and hall sensor signal H2 316, it can be observed that when VRY voltage waveform 310 is positive, hall signal H2 = 0, and when VRY voltage waveform 310 is negative, hall signal H2 = 1. In a similar manner, referring to VYB line voltage waveform 308 and hall sensor signal H3 318, it can be observed that when VYB voltage waveform 308 is positive, hall signal H3 = 0, and when VYB voltage waveform 308 is negative, hall signal H3 = 1.
[00034] Fig. 3 illustrates a conventional zero crossing detection circuit 400 with only two interrupts for 360 degrees of electrical rotation. In case of such a conventional circuits, a standard single phase semi-converter topology is used for voltage regulation. In standard semi-converter, a conventional zero crossing detector circuit 400 is used to detect zero crossing of back e.m.f voltage and accordingly delay the firing angle to control output voltage waveform 404. Such standard zero crossing detection method is useful for domestic applications where the AC supply source frequency will not deviate (50+/-5Hz). But in a vehicle the engine speed variation is very much dynamic and firing angle control circuit should be able to adapt to these dynamic changes without delay. Delay or advance in firing angle error due to the method selected has significant effect on charging current and applied voltage to the battery. If firing is advanced by some angle due to error in estimation, then battery will be charged with very high current and the vehicle electrical loads will see a higher voltage ripple. If firing is delayed by some angle due to error in estimation, then battery will be charged with less current. The present subject matter provides a firing angle control circuit as illustrated in Fig. 5, which overcomes the problems, faced in the standard zero crossing detection circuit as depicted in Fig. 3.
[00035] Fig. 4 illustrates a charging current path 200 during generation mode of the ISG control circuit as shown in Fig. 1, in accordance with an embodiment of the present subject matter. In an embodiment, after successful start of engine, the controller will change to charging mode by disabling PWMs and deactivating relays Relay 1 106, Relay 2 108, and Relay 3 110. In this example it is assumed that H1=0. Accordingly, the controller will give firing signal 510 (shown in Fig. 5) to SCR X2 136 after calculated delay time based on charging current requirement. Once the SCR X2 136 starts conducting, anti-parallel diode in MOSFET M2 124 will start conducting and charge the battery 104.
[00036] In an embodiment, phase controlled rectifier is used to control the average charging current to the battery 104. During generation mode, high side contactor relay, for example Relay 3 110, is de-energized to avoid uncontrolled rectification by MOSFET’s (M1, M2, M3, and M4) anti-parallel diodes. SCR’s X1 134 and X2 136, switching is done based on engine RPM, Motor back e.m.f constant Ke, input signals received from Hall sensors H1, H2, and H3, battery voltage, and required average charging current. In an embodiment, bottom MOSFET’s M3, M4 internal diodes are used as rectifier diodes and SCR’s X1 134 and X2 136 are used as control switches. For example, referring to the charging current path as depicted in Fig. 4, whenever inverter leg L1 is at higher potential than inverter leg L2, SCR X1 134 is turned ON at a required phase angle according to the average charging current requirement and internal diode of MOSFET M4 will conduct automatically as it receives a forward voltage during this time. Similarly, whenever inverter leg L2 is at higher potential than inverter leg L1, SCR X2 136 is turned ON at a required phase angle according to the average charging current requirement and internal diode of MOSFET M3 will conduct automatically due to forward voltage. In an embodiment, the present subject matter includes only four MOSFETs, two gate drivers against six MOSFETs, and three gate drivers of conventional circuit; the cost of the MOSFET bridge is largely reduced.
[00037] For instance, by following the charging control circuit 200 as depicted in Fig. 4, once engine is started, the controller will check whether the engine speed has crossed minimum charging speed or not. Based on the same, if the engine speed crosses minimum limit, the controller will change its mode from motoring to generation mode by disabling all PWM signals to the MOSFETs and deactivating the relays: Relay 1 106, Relay 2 108 and Relay 3 110. In an implementation, relay 1 and relay 2 are deactivated to reduce continuous energy loss in relay coils. After deactivation of the relays, Phase R is connected to inverter leg L1 and Phase B is connected to inverter leg L2, while Relay 3 110 is deactivated to stop uncontrolled charging of the battery. Now based on engine speed, the controller will be able to estimate the exact rotational electrical angle. This angle can be used for achieving optimal firing angle control as depicted in Fig. 5 below.
[00038] For example, based on hall sensor signal H1, the controller will decide which SCR out of SCRs X1 134 and X2 136 to be fired for charging. For instance, when H1 = 1, SCR X1 134 will be selected for firing angle control since inverter leg L1 potential is higher than inverter leg L2.
[00039] Similarly, when H1 = 0, SCR X2 136 will be selected for firing angle control, since inverter leg L2 potential is higher than inverter leg L1.Once appropriate SCR is selected, the controller will determine after how much delay time the selected SCR X1 134 or SCR X2 136 should be fired (turned ON) to charge the battery 104 for a given charging current demand. Once SCR is fired, the anti-parallel diode in the other inverter leg will start conducting. Thus, the conducting SCR will switch OFF when current falls to zero and reveres voltage is applied. Reverse voltage will appear across the device after the next zero crossing point where SCR inverter side point potential (voltage) is negative compared to the battery charging point (current sensor point).
[00040] In an implementation, the above steps will be repeated continuously to charge the battery as long as the engine speed is above the minimum required speed.
[00041] Fig. 5 illustrates a firing angle control circuit 500, in accordance to an embodiment of the present subject matter. In an embodiment, the present subject matter includes only hall sensor signals H1, H2, or H3 to detect zero crossing and firing angle is delayed based on the angular velocity determined based on the hall sensor signal output. Firing control using hall sensor is more accurate than standard firing angle delay calculation, since three hall sensor signals will give six interrupts (1 interrupt at every 60 degree (electrical) rotation) within one electrical 360 degree rotation. However, in case of conventional zero crossing detection circuit, only two interrupts will come for 360 degrees electrical rotation.
[00042] Due to more number of interrupts in the firing angle control circuit 500 depicted in Fig. 5, the present subject matter provides a firing angle estimation or velocity estimation that is more accurate compared to the standard zero crossing detection method. Further, due to better angle estimation, the firing angle control is enhanced. Due to more number of interrupts per rotation, the firing angle control circuit 500 of the present subject matter can adapt to dynamic engine speed changes.
[00043] Many modifications and variations of the present subject matter are possible in the light of above disclosure. Therefore, within the scope of claims of the present subject matter, the present disclosure may be practiced other than as specifically described.
,CLAIMS:We claim:
1. An integrated starter generator system (100) for a two/three wheeled vehicle comprising:
a three-phase electrical machine (112) mounted on a crankshaft of an internal combustion engine of said vehicle, said electrical machine (112) capable of motoring said internal combustion engine until said engine is cranked, said electrical machine (112) capable of generating electrical energy after said engine is cranked;
one or more sensors (H1, H2, H3) disposed at least on a stator surface of said electrical machine (112) for detecting rotational position of at least a rotor of said electrical machine (112);
an electronic controller capable of controlling motoring and generating of electrical energy by said electrical machine (112), said electronic controller having a first inverter leg (L1) and a second inverter leg (L2) activates at least a first combination of two phases (114, 116, 118) of said three-phase electrical machine (112) based at least on rotational position of said rotor detected by said one or more sensors (H1, H2, H3); and
said first inverter leg (L1) and said second inverter leg (L2) electronically coupled to a first relay (106) and a second relay (108), wherein
said first relay (106) and said second relay (108) are turned ON/OFF to activate at least a second combination of two phases (114, 116, 118) of said three-phase electrical machine (112) based at least on a pre-determined acceleration level of said electrical machine (112), and wherein, said first relay (106) and said second relay (108) are turned OFF when said electrical machine (112) exceeds said pre-determined acceleration level.
2. The integrated starter generator system (100) as claimed in claim 1, wherein said electrical machine (112) is a BLDC electric motor (112).
3. The integrated starter generator system (100) as claimed in claim 1, wherein said one or more sensors (H1, H2, H3) are Hall Effect position sensors (H1, H2, H3).
4. The integrated starter generator system (100) as claimed in claim 1, wherein said three-phase electrical machine (112) includes a first motor phase R (114), a second motor phase B (116), and a third motor phase G (118).
5. The integrated starter generator system (100) as claimed in claim 1 or 4, wherein when said first relay (106) and said second relay (108) are in OFF condition, said first combination of two phases includes said first motor phase R (114) coupled to said first inverter leg (L1) and said second motor phase B (116) coupled to said second inverter leg (L2).
6. The integrated starter generator system (100) as claimed in claim 1 or 4, wherein when said first relay (106) is in OFF condition, and said second relay (108) is in ON condition, said second combination of two phases includes said first motor phase R (114) coupled to said first inverter leg (L1) and said third motor phase G (118) coupled to said second inverter leg (L2).
7. The integrated starter generator system (100) as claimed in claim 1 or 4, wherein when said first relay (106) and said second relay (108) are in ON condition, a third combination of two phases includes said second motor phase B (116) coupled to said first inverter leg (Ll) and said third motor phase G (118) coupled to said second inverter leg (L2).
Dated this day of 2017

S. Ramiah
General Manager – R&D
TVS Motor Company Limited