DESC:FIELD OF INVENTON
[0001] The invention relates to a short circuit protection of automobiles and more particularly, it relates to protection of the motor controller unit in the event of short circuit in automobiles.

BACKGROUND OF THE INVENTION
[0002] Electric vehicles employ electrical motors, such as BLDC (Brushless DC) motors, to propel the vehicles. These motors work in conjunction with the Main Battery, Motor Controller Unit (MCU), Auxiliary Battery, Vehicle Control Unit (VCU), and additional low-voltage control components.
[0003] Within BLDC motors, sensors such as hall sensors, play crucial role in monitoring rotor’s position and speed. These sensors require a 5V power supply, which is supplied from the auxiliary battery and the neutral terminal of the hall sensors terminates to a sensor ground.
[0004] Conventionally, BLDC motor contains a single bundle containing three phase wires. These wires serves the purpose of supplying power to the motor, providing the 5V sensor power supply, and connecting to neutral terminal of the hall sensor.
[0005] In challenging conditions as well as due to aging and rough handling, there is a potential risk of physical contact between the phase wire and the sensor’s neutral terminal that could results in a short circuit.
[0006] The excessive current produced by a short circuit can lead to overcurrent conditions. Such overcurrent situations can potentially damage wires, components, and devices in the circuit, and can pose a safety hazard leading to electrical fires and risk of equipment damage. Moreover, components or devices downstream of the short circuit such as low ohm resistor, semiconductor devices located near the sensor ground may experience a voltage level higher than their design specifications, potentially leading to overvoltage conditions. This can results in damage or stress to these components, ultimately leading to potential failures. This sequence of events further results in irreversible harm to the sensor power supply circuit, necessitating the frequent replacements of the MCU by the vehicle user, which is a costly component.
[0007] Some existing solutions or state of the art methods suggest the presence of a voltage evaluation circuit at the sensor terminals which detects abrupt voltage in the neutral terminal wire. Although this may be effective for components having high tolerance limits against overvoltage for some period of time as the detection circuit has a certain time lag to dislodge the circuit during abnormal conditions, but it is ineffective for sensitive electronic components situated at the sensor ground. Additionally, the voltage evaluation circuits may possess certain elements which are cost intensive including expensive controllers and requires lot of space. Furthermore, in situations where there is no high voltage but high current flow through ground point, the voltage protection circuits may not provide necessary protection, particularly when a motor operates as a generator during regenerative braking operation of electric vehicles.

OBJECT OF THE INVENTION
[0008] An objective of the invention is to provide an efficient protection circuit aimed at safeguarding the motor control unit (MCU) against potential damage resulting from overvoltage or over current events arising from wire short circuits.
[0009] Another objective of the invention is to provide a protection system, which is having a compact and a cost-effective design, ensuring the preservation and integrity of critical and sensitive circuit components.
[0010] Still another objective of the invention is to effectively eliminate the impact of over voltage on key sensitive circuit components.
[0011] Yet another objective of the invention is to reduce the frequency of servicing and replacement of the MCU by preventing damage to the controller (ECU) in the event of a short circuit.
[0012] Still another objective of the invention is to overcome lacunas of existing systems explained in background section.

SUMMARY OF THE INVENTION
[0013] With the aforementioned objectives in mind, the present invention provides a system for protection of an electrical circuit in an automobile, comprising:
[0014] at least an electrical conductor connecting an electrical component to a ground terminal of the electrical circuit for current flow;
[0015] at least a switching device to connect or disconnect the atleast one electrical conductor from the ground terminal; wherein the atleast one switching device is operated using at least one of a current limiter circuit, a voltage detection unit,
[0016] wherein; the current limiter circuit is configured to monitor current in the electrical conductor and operates the switching device to control the current flow in the electrical conductor ;
[0017] wherein; the voltage detection unit is configured to monitor voltage across the electrical conductor; and actuates the switching device to disconnect the electrical conductor from the ground terminal when the voltage across the electrical conductor exceeds a predetermined permissible limit.
[0018] The current limiter is configured to latch current to a predetermined value within the range of 250 to 350 mA.
[0019] The voltage detector unit operates the switching device to disconnect the electrical conductor from the ground terminal within maximum response time of 15 microseconds.
[0020] The switching device further includes metal-oxide semiconductor field-effect transistors (MOSFET’s) or insulated-gate bipolar transistor (IGBT) or thyristors, bipolar junction transistors (BJTs).
[0021] The voltage detection unit provides signal to a control & latch circuit operating the switching device to disconnect the electrical conductor from the ground terminal when voltage across the electrical conductor exceeds permissible limit beyond 10 V during short circuit of the electrical conductor with at least a power supplying conductor.
[0022] The control & latch circuit is designed to transmit a signal to a controller in the event of a high voltage detection in the electrical conductor.
[0023] The controller is in communication with a remote device or a cloud server or a display unit of the automobile through a communication means including controller area network (CAN) or Ethernet or wired or wireless connection including cloud deployment, for facilitating information to the operator including audio warning.
[0024] A system for protection of an electrical circuit in an automobile, comprising: at least an electrical conductor configured to connect an electrical component to a ground terminal of the electrical circuit to enable current flow; wherein the electrical conductor is further connected to a power source earth terminal with at-least a thick wire and current passes through the thick wire in the event the current in the thick wire exceeds permissible limit.
[0025] The systems for protection of an electrical circuit in an automobile comprising a power source for providing three phase power to a motor (M) by at least a power supplying conductor (R, Y, B) through an inverter; at least a control unit comprising a motor control unit for controlling the motor (M); an auxiliary power source providing power to an electrical component by a positive electrical conductor through a power supply regulator; an electrical conductor connecting an electrical component to a ground terminal; wherein the electrical conductors are bundled with at least a power supplying conductor (R, Y, B) of the electric motor (M).
[0026] The control unit comprises key sensitive electronic components including low ohm resistor, electronic voltage regulator, semiconductor elements placed at one end at the ground terminal to eliminate noise and interference.
[0027] The electrical component is a hall sensor configured to sense the position and speed of a rotor of the electric motor (M). The system is incorporated in hybrid, battery operated two-wheeled, three-wheeled or four-wheeled electric vehicles.
[0028] The system includes a monitoring system configured to discontinue power delivery from the battery by a gate driver in inverter when a predetermined current limit is exceeded, thereby providing effective protection to the electrical circuit, and to relay a signal to a display device, which includes an audio warning.
[0029] The power source earth terminal has lower electric potential than the electric potential of ground terminal of the control unit facilitating current flow to the power source earth terminal when current exceeds a threshold value.
[0030] The thick wire terminating at the power source earth terminal is connected to the electrical conductor at a point before the electrical conductor is connected to the key sensitive electronic components.
[0031] The protection system comprises a voltage sensor connected on the power supply regulator of the electrical component and; wherein, the voltage sensor is connected to at least a controller to detect abrupt increase of voltage and relay to a display device.
[0032] The display device indicates the location of a fault and the key sensitive electronic components remains protected from both overvoltage & overcurrent conditions.
[0033] A method for protection of an electrical circuit in an automobile, comprises: operating a switching device using at least; a current limiter circuit, a voltage detection unit;
[0034] actuating the switching device to connect or disconnect an electrical conductor connecting an electrical component to a ground terminal; controlling overcurrent with the help of a current limiter in an electrical conductor; detecting by means of a voltage detection unit whether voltage across the electrical conductor is greater than a predetermined permissible limit; actuating at least a switching device to disconnect the electrical conductor from the ground terminal when voltage across electrical conductor exceeds a predetermined permissible limit.

BRIEF DESCRIPTION OF DRAWINGS
[0035] The above and other objects, features, and advantages of the present disclosure will be more apparent from the detailed description taken in conjunction with the accompanying drawings. One or more embodiments of the present invention are now described, by way of example only with reference to the accompanied drawings wherein like reference numerals represent like elements.
[0036] FIG. 1 shows a proposed architecture of the electrical circuit protection system in automobiles according to one of the embodiments of the present invention;
[0037] FIG.2 shows steps of a working operation of key features leading to electrical circuit protection system in automobiles according to the present invention;
[0038] FIG. 3 shows response time of the operation of switch to disconnect the wire from the ground terminal when voltage across wire exceeds permissible limit according to the present invention;
[0039] FIG. 4 displays proposed architecture of the electrical circuit protection system in automobiles according to another embodiment of the present invention;
[0040] FIG. 5 shows steps of a working operation of key features leading to electrical circuit protection system in automobiles according to another embodiment of the present invention.

DETAILED DESCRIPTION
[0041] The invention along with preferred embodiments will now be described in detail with reference to the accompanying drawings. The preferred embodiment does not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.
[0042] It will be readily understood that components of the present invention, as generally described and illustrated in figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the invention as represented in the figures is not intended to limit the scope of the invention but is merely representative of certain examples of presently contemplated embodiments in accordance with the invention. The presently described embodiments will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout.
[0043] The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in respect as illustrative and not restrictive.
[0044] According to FIG.1, a schematic architecture of an electrical circuit protection system (20) in automobiles has been shown. A Direct Current (DC) input from a power source (7) preferably a battery having 48V capacity is fed into a three phase inverter (5), which is a key component of a control unit (19) preferably a Motor Control Unit (MCU). The three phase inverter (5) is used to convert DC power, typically from the DC source like the main battery (7) into three-phase AC power. The operation of a three-phase inverter (5) involves converting the DC voltage into a three-phase (R, Y, B) AC voltage with the desired frequency and amplitude for operation a motor (M). In the present embodiment a Brushless Direct Current Motor (BLDC motor) (M) is used to act as a prime mover for the automobile; exemplarily battery operated electric vehicle, hybrid vehicles, plug-in Hybrid Electric Vehicles.
[0045] Further, the MCU (19) comprises a circuitry for an auxiliary power source (8), which supplies power to the power supply regulator (6) which may convert 12 V to 5 V required for power supply through a positive electrical conductor (9) to the sensors, preferably Hall effect sensors (not shown) although other sensors may be used. The hall effect sensors are commonly used in Brushless DC (BLDC) motors to determine the rotor's position, which is crucial for controlling the commutation of the motor. BLDC motors are electronically commutated, meaning they require precise timing and control to operate efficiently. The hall effect sensors play a significant role in achieving this control. An electrical conductor (11) of the hall sensor is connected to a ground terminal (18) through a wire having considerable impedance.
[0046] FIG.2 illustrates steps of a working operation of key features leading to electrical circuit protection system & in conjunction with FIG.1. The electrical conductor (11) may have key sensitive electronic components (13) downstream, importantly a resistor having 0 ohm or considerably low ohmic resistance value, further there may be some semiconductor switches such as bipolar junction transistors, electronic voltage regulators susceptible to inadvertent voltage & current rise.
[0047] These components such as electronic voltage regulators are required to regulate voltage and provide a stable and precise output voltage even when the input voltage fluctuates. This is significant because many electronic components require a specific voltage level for proper operation. The voltage regulators such as Low Dropout Regulator (LDO) is used in the present invention typically provides cleaner and lower-noise power compared to some other voltage regulation methods. Further, the 0-ohm resistance component at the ground terminal (18) of the control unit (19) signifies that there is a direct and low-resistance connection to the ground, ensuring a common reference point for the sensor and the rest of the circuit. This is essential to prevent ground loops and ensure proper functioning of the sensor. As, having a zero-ohm resistance at the ground terminal (18) means there is no voltage drop across the ground path. It helps maintain a stable ground reference across the entire circuit, ensuring consistent and accurate measurements from the Hall sensor.
[0048] It has been observed that, for the ease of packaging and providing a sole power supply point, the three phase wires (R, Y, B) terminal point of the motor (M) and the terminal points of the sensors are branched together. However, during manual servicing or when the automotive vehicle is subjected to harsh weather conditions, particularly in wet environments, there may be a possibility that the phase wires (R, Y, B) of the motor (M) may get in physical contact with the electrical conductor (11) of the hall sensor wire. This results in short circuit leading to both overcurrent as well as overvoltage conditions in the wire that connects the electrical conductor (11) to the ground terminal (18).
[0049] The key sensitive electronic components (13) like resistor having 0 ohm or considerably low ohmic resistance value, semiconductor switches such as bipolar junction transistors, electronic voltage regulators components that forms an integral part of the MCU (19) is damaged by such High voltage & over current due to low tolerance limit & negligible impedance for these components. Due to these instances, frequent replacement of MCU (19) is necessitated which not only incur high cost, but also requires manual supervision & labour. Further, in case of electric vehicle, which use regenerative braking to recharge their small batteries, the motor (M) may act as a generator leading to flow of current through the three phase wires (R, Y, B). In such circumstances, when short circuit of these phase wires happen with the sensor electrical conductor (11), huge current, having negligible voltage may also flow through the electronic components, adversely impacting them. Therefore a current limiting circuit (2) circuit is necessitated in the first protection circuit (20).
[0050] The current limiting circuit (2), is a device used to prevent excessive current flowing through a load or a component. These circuits are essential for protecting sensitive components, preventing overheating, and ensuring the safe operation of electrical or electronic systems. Preferably, a transistor-based switching device (1) may be used in conjunction with current limiting circuits is used to control and limit the amount of current flowing through a load or component. They work by adjusting the bias voltage or gate voltage of a transistor to regulate the current. The specific type of transistor used (bipolar junction transistor, or BJT, and field-effect transistor, or FET) will determine the circuit's behavior. Also, a resistance in series may be used in the current limiting circuit. The current limiting circuit (2) limits the current to predetermined value preferably in the range of 250 to 350 mA in the event of current surpassing the threshold value to protect the circuit components (13) on the wire at the ground terminal (18).
[0051] Moreover, the first protection circuit (20) may also comprise a voltage regulator circuit (3). The voltage regulator circuit (3) with BJTs can be used to protect sensitive electronic components from overvoltage conditions. If the input voltage exceeds a safe limit, the BJT can be configured to disconnect or shunt the excess voltage to protect downstream circuitry. Voltage sensing using BJTs with a control and latch circuit (4) is used to provide a method for detecting a specific voltage level and holding the output in a particular state until reset. This is often used for applications such as overvoltage protection. A control and latch circuit (4) is designed to control the (ON/OFF) state of a semiconductor switch (1) based on certain input conditions and latch that state until reset. Key components of such a circuit may include resistances & semiconductor devices such as Bipolar Junction Transistors. When the voltage at the electrical conductor (11) is greater than the preprogrammed value that is (near to 48V) the voltage regulator (3) senses high voltage & sends signal to control & latch circuit (4). The control & latch circuit (4) opens the switch (1) & sends fault signal to a controller (12). The ground terminal (18) along with key sensitive components (13) are isolated from rest of the circuit, thus protecting the internal the key sensitive components (13) such as LDO, resistor, BJT etc. The fault signal can be represented in display, sending information through CAN communication to display, or be provided in a remote device with or without an alarm.
[0052] According to FIG.3, a response time of the operation of switch (1) to disconnect the wire from the ground terminal (18) when voltage at sensor electrical conductor (11) exceeds permissible limit according to the present invention is depicted. The response time is preferably less than 10 microseconds, and according to one exemplary embodiment, the response time is 8 micro-seconds (depicted by the blue curve). The fast response time protects the key sensitive electronic components (13) such as the low ohm resistor, LDOs & semiconductor devices, present in the MCU (19) and precisely at the ground terminal (18) position of the sensor neutral terminal wire from possible malfunctioning.
[0053] According to another embodiment of the present invention as illustrated in FIG. 4, another architecture of the electrical circuit protection system (21) in automobiles is described herein. The motor configuration comprising of three phases (R,Y,B), a 48V input battery (7) with a three phase inverter (5) & a magnetic field sensing circuit for the motor (M) is altogether the same as described in the previous embodiment herein above, although the second protection circuit (21) is devised in a different configuration.
[0054] According to FIG. 5 it schematically depicts steps of a working operation of key features leading to an electrical circuit protection system (21) in automobiles according to the embodiment depicted in FIG. 4. When one of the phase wires (R,Y,B) are shorted with the sensor electrical conductor (11) high current passing from the battery (7) to the phase (R or Y or B) finally reaches the sensor ground terminal (18), damaging the key sensitive electronic components (13). To obviate this, an alternate path is devised using a thick wire (16) comprising of a thick conductor connected to the neutral wire of the sensor between the electrical conductor (11) & the point where the wire is connected to the key sensitive electronic components (13) (low ohm resistor, LDO, BJT) finally terminating to a power source earth terminal (17). The thick wire (16) is provided proximate to the electrical conductor (11) of the hall sensor. Therefore during short circuit conditions, the current has two parallel paths as one through the key sensitive electronic components (13) and another through the thick wire (16). In case of short circuit with phase wire, the current flows through the thick wire (16) as it has the lower impedance compared to the wire path possessing the key sensitive electronic components (13). The voltage at thick wire (16) terminating to the power source earth terminal (17) has lower electric potential than the electric potential of ground terminal (18) to thick wire point facilitating current flow to the power source earth terminal (17) when current exceeds a threshold value. The high current flow is interrupted by a gate driver present in an inverter (5) preferably a three phase inverter and latch it as permanent fault, until the cause is extinguished. The secondary protection circuit comprises of a voltage sensor (14) for the sensor wires (positive & neutral wire). The voltage sensor (14) output is fed to a controller (12). The controller (12) is able to detect any abrupt increase of voltage and further relay to a display device in case of overvoltage due to short circuit conditions. Hence, the operator is able to gauge the fault location and key sensitive electronic components (13) remains protected from both overvoltage & overcurrent.
[0055] Although the exemplary forms of the present disclosure have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the present disclosure.

Reference Numerals:-
[0056] Three phase- (R,Y,B)
[0057] Motor- (M)
[0058] Switch-(1)
[0059] Current limiter- (2)
[0060] Voltage Detection Unit (3)
[0061] Control & Latch circuit (4)
[0062] Inverter- (5)
[0063] Voltage regulator – (6)
[0064] Power source - (7)
[0065] Auxiliary power source- (8)
[0066] positive electrical conductor - (9)
[0067] electrical conductor (11)
[0068] controller- (12)
[0069] Key Sensitive Electronic Components- (13)
[0070] Voltage sensor- (14)
[0071] thick wire - (16)
[0072] power source earth terminal (17)
[0073] ground terminal (18)
[0074] control unit- (19)
[0075] First Protection Circuit- (20)
[0076] Second Protection Circuit- (21)
,CLAIMS:We Claim:
1. A system (20) for protection of an electrical circuit in an automobile, comprising:
at least an electrical conductor (11) connecting an electrical component to a ground terminal (18) of the electrical circuit for current flow;
at least a switching device (1) to connect or disconnect the atleast one electrical conductor (11) from the ground terminal (18); wherein the atleast one switching device (1) is operated using at least one of a current limiter circuit (2), a voltage detection unit (3),
wherein; the current limiter circuit (2) is configured to monitor current in the electrical conductor (11) and operates the switching device (1) to control the current flow in the electrical conductor (11) ;
wherein; the voltage detection unit (3) is configured to monitor voltage across the electrical conductor (11); and actuates the switching device (1) to disconnect the electrical conductor (11) from the ground terminal (18) when the voltage across the electrical conductor (11) exceeds a predetermined permissible limit.
2. The system (20) for protection of an electrical circuit in an automobile as claimed in Claim 1 wherein, the current limiter (2) is configured to latch current to a predetermined value within the range of 250 to 350 mA.
3. The system (20) for protection of an electrical circuit in an automobile as claimed in Claim 1 wherein, the voltage detector unit (3) operates the switching device (1) to disconnect the electrical conductor (11) from the ground terminal (18) within maximum response time of 15 microseconds.
4. The system (20) for protection of an electrical circuit in an automobile as claimed in Claim 1, wherein the switching device (1) further includes metal-oxide semiconductor field-effect transistors (MOSFET’s) or insulated-gate bipolar transistor (IGBT) or thyristors, bipolar junction transistors (BJTs).
5. The system (20) for protection of an electrical circuit in an automobile as claimed in Claim 1 wherein, the voltage detection unit (3) provides signal to a control & latch circuit (4) operating the switching device (1) to disconnect the electrical conductor (11) from the ground terminal (18) when voltage across the electrical conductor (11) exceeds permissible limit beyond 10 V during short circuit of the electrical conductor (11) with at least a power supplying conductor.
6. The system (20) for protection of an electrical circuit in an automobile as claimed in Claim 5 wherein, the control & latch circuit (4) is designed to transmit a signal to a controller (12) in the event of a high voltage detection in the electrical conductor (11).
7. The system (20) for protection of an electrical circuit in an automobile as claimed in Claim 6 wherein, the controller (12) is in communication with a remote device or a cloud server or a display unit of the automobile through a communication means including controller area network (CAN) or Ethernet or wired or wireless connection including cloud deployment, for facilitating information to the operator including audio warning.
8. A system (21) for protection of an electrical circuit in an automobile, comprising:
at least an electrical conductor (11) configured to connect an electrical component to a ground terminal (18) of the electrical circuit to enable current flow;
wherein the electrical conductor (11) is further connected to a power source earth terminal (17) with at-least a thick wire (16) and current passes through the thick wire (16) in the event the current in the thick wire (16) exceeds permissible limit.
9. The systems (20, 21) for protection of an electrical circuit in an automobile, as claimed in Claim 1 or 8 comprising:
a power source (7) for providing three phase power to a motor (M) by at least a power supplying conductor (R, Y, B) through an inverter (5);
at least a control unit (19) comprising a motor control unit for controlling the motor (M);
an auxiliary power source (8) providing power to an electrical component by a positive electrical conductor (9) through a power supply regulator (6);
an electrical conductor (11) connecting an electrical component to a ground terminal (18);
wherein the electrical conductors (9, 11) are bundled with at least a power supplying conductor (R, Y, B) of the electric motor (M).
10. The systems (20, 21) for protection of an electrical circuit in an automobile, as claimed in Claim 9 wherein the control unit (19) comprises key sensitive electronic components (13) including low ohm resistor, electronic voltage regulator, semiconductor elements placed at one end at the ground terminal (18) to eliminate noise and interference.
11. The systems (20, 21) for protection of an electrical circuit in an automobile, as claimed in Claim 1 or 8 wherein, the electrical component is a hall sensor configured to sense the position and speed of a rotor of the electric motor (M).
12. The systems (20, 21) for protection of an electrical circuit in an automobile, as claimed in Claim 1 or 8, wherein the system (20, 21) is incorporated in hybrid, battery operated two-wheeled, three-wheeled or four-wheeled electric vehicles.
13. The system (21) for protection of an electrical circuit in an automobile, as claimed in Claim 9 wherein the power source (7) includes a monitoring system configured to discontinue power delivery from the battery by a gate driver in inverter (5) when a predetermined current limit is exceeded, thereby providing effective protection to the electrical circuit, and to relay a signal to a display device, which includes an audio warning.
14. The system (21) for protection of an electrical circuit in an automobile, as claimed in Claim 9, wherein the power source earth terminal (17) has lower electric potential than the electric potential of ground terminal (18) of the control unit (19) facilitating current flow to the power source earth terminal (17) when current exceeds a threshold value.
15. The system (21) for protection of an electrical circuit in an automobile, as claimed in Claim 8 wherein the thick wire (16) terminating at the power source earth terminal (17) is connected to the electrical conductor (11) at a point before the electrical conductor (11) is connected to the key sensitive electronic components (13).
16. The system (21) for protection of an electrical circuit in an automobile, as claimed in Claim 9 wherein the protection system comprises a voltage sensor (14) connected on the power supply regulator (6) of the electrical component and; wherein, the voltage sensor (14) is connected to at least a controller (12) to detect abrupt increase of voltage and relay to a display device.
17. The systems (20, 21) for protection of an electrical circuit in an automobile, as claimed in Claims 7 or 13 or 16, wherein the display device indicates the location of a fault and the key sensitive electronic components (13) remains protected from both overvoltage & overcurrent conditions.
18. A method for protection of an electrical circuit in an automobile, comprises:
operating a switching device (1) using at least; a current limiter circuit (2), a voltage detection unit (3);
actuating the switching device (1) to connect or disconnect an electrical conductor (11) connecting an electrical component to a ground terminal (18);
controlling overcurrent with the help of a current limiter (2) in an electrical conductor (11);
detecting by means of a voltage detection unit (3) whether voltage across the electrical conductor (11) is greater than a predetermined permissible limit;
actuating at least a switching device (1) to disconnect the electrical conductor (11) from the ground terminal (18) when voltage across electrical conductor (11) exceeds a predetermined permissible limit.