Description:FIELD OF THE INVENTION
The embodiments of the present disclosure relate generally to a circuit to protect vehicle’s battery and charger from short-circuit and reverse polarity and more particularly to an integrated circuit that protects the battery charger against both reverse polarity and short-circuit events.
BACKGROUND
Battery-powered vehicles or Electric vehicles are becoming increasingly important in today’s world. The battery is the heart of any electric vehicle and the charger is vital for its operation, i.e. for charging the battery to keep it running. Both components are critical and need reliable protection to ensure safe and efficient operation.
However, battery packs and chargers are exposed to several potential risks, such as short-circuits, reverse polarity connections, and even the possibility of fire. It is essential to protect short-circuit events that could damage both the battery and the charger. Also, it is essential to block reverse current that could drain or harm the battery or harm the charger. There is a possibility of a short-circuit event appearing at the output of the charger due to mishandling or any other reason. Also, if the charger terminals and the battery terminals are not connected properly, or if the positive terminal of the battery is connected to the negative output terminal and the negative terminal of the battery is connected to the positive output terminal, there are chances of reverse polarity which could drain or harm the battery and the charger due to excess current flow. To manage these risks, various vehicle manufacturers have developed different protective solutions. Many of these involve separate electronic circuits for each risk, which can make the design more complicated. These solutions often require multiple components, extra power supplies, and can be expensive to implement.
3
Hence, there’s a need for a simpler and integrated system that can protect the battery from multiple kinds of faults, without adding unnecessary complexity or cost and if there is any fault in the system, it is triggered automatically.
OBJECTS OF THE INVENTION
1.
The primary objective of the present invention is to protect battery charging systems from both short-circuit and reverse polarity by a single integrated circuit.
2.
Another objective of the present invention is to offer a self-powered and self-sustained circuit capable of automatically detecting and triggering a fault when necessary.
3.
Yet another objective of the present invention is to provide a protection mechanism that ensures safe and efficient charging of the vehicle's battery.
SUMMARY OF THE INVENTION
The present invention aims to provide an integrated circuit for reverse polarity and short-circuit protection in battery charging systems, a circuit comprising a main semiconductor switch configured to enable power transfer from a charger to a battery under normal operating conditions and to disconnect the charger and the battery during abnormal conditions to prevent current flow, a detection diode configured to monitor voltage levels across the said circuit and control the main semiconductor switch, a short-circuit current trip element configured to turn OFF the main semiconductor switch upon detecting a short-circuit event, a gate control circuit comprises of one or more switches, one or more resistors and one or more diodes configured to control ON and OFF states of the main semiconductor switch based on predefined circuit conditions and a fault indication circuit configured to indicate presence of fault within the system and provide a warning or alert when abnormal conditions are detected.
As per the first embodiment of the present invention, the gate control circuit comprises a transistor (Q3) configured to activate transistor (Q4) upon detecting a sufficient voltage based on the short-circuit trip element (+-R19) and the detection diode (D6), the transistor (Q4) configured to turn OFF the main semiconductor switch by pulling the gate-source voltage low during operation, a resistor (R8) configured to limit and regulate the current through the gate control circuit during operation, resistors (R10, R17) and capacitor (C2) configured to form a bias circuit to provide stability to the gate control circuit and enable initial excitation of the main semiconductor switch, wherein the capacitor (C2) facilitates the turn ON process of the main semiconductor switch and Zener diodes (D5, D7, D8) configured to protect the transistor (Q3), transistor (Q4) and main semiconductor switch (SW1)..
As per the second embodiment of the present invention, the main semiconductor switch is a device configured to operate with a positive gate voltage threshold relative to the charger’s negative terminal.
As per the third embodiment of the present invention, the detection diode is configured to be forward biased in nominal conditions and the voltage at its anode is insufficient to cause the gate control circuit to turn OFF the main semiconductor switch.
As per the fourth embodiment of the present invention, the detection diode is configured to be reverse biased during a reverse polarity event, causing the anode voltage of the detection diode to rise above a predefined threshold, thereby activating the gate control circuit to turn OFF the main semiconductor switch.
As per the fifth embodiment of the present invention, the detection diode is configured such that the anode voltage rises during the short-circuit event, triggering the gate control circuit to turn OFF the main semiconductor switch.
As per the sixth embodiment of the present invention, the transistors are selected from one of a P-MOS, an N-MOS, a PNP, an NPN or transistors of equivalent type.
As per the seventh embodiment of the present invention, the short circuit current trip element is selected from one of a resistor, a Zener, a TVS diode of a specific breakdown voltage rating, or a series of p-n junction diodes.
As per the eight embodiment of the present invention, the fault indication circuit comprises an LED indicator or an audio alarm configured to provide a visual or audible alert when an abnormal condition is detected.
As per the ninth embodiment of the present invention, the main semiconductor switch is configured to be a MOSFET selected from the group consisting of an N-channel MOSFET, a P-channel MOSFET, N-channel IGBT or equivalent type transistors, depending on circuit polarity requirements.
As per the tenth embodiment of the present invention, the circuit is powered by either the battery voltage or the charger output voltage, and is configured to operate as a self-contained unit, requiring no intervention from a microcontroller, external circuitry, or software.
BRIEF DESCRIPTION OF THE DRAWINGS
The disclosure will be described and explained with additional specificity and detail with the accompanying figures in which:
FIG.1 illustrates an integrated circuit for protection against short-circuit and reverse polarity, in accordance with the present invention.
FIG. 2 is a gate control circuit of an integrated circuit, in accordance with the present invention.
FIG. 3 is a fault indication circuit of an integrated circuit, in accordance with the present invention.
Further, those skilled in the art will appreciate that elements in the figures are illustrated for simplicity and may not have necessarily been drawn to scale. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the figures by conventional symbols, and the figures may show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the figures with details that will be readily apparent to those skilled in the art having the benefit of the description herein.
DETAILED DESCRIPTION
For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the figures and specific language will be used to describe them. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as would normally occur to those skilled in the art are to be construed as being within the scope of the present invention.
It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof.
The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such a process or method. Similarly, one or more devices or sub-systems or elements or structures or components preceded by "comprises... a" does not, without more constraints, preclude the existence of other devices, sub-systems, elements, structures, components, members, additional devices, additional sub-systems, additional elements, additional structures or additional components. Appearances of the phrase "in an embodiment", "in another embodiment" and similar language throughout this specification may, but not necessarily do, all refer to the same embodiment.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention belongs. The system, methods, and examples provided herein are only illustrative and not intended to be limiting.
Embodiments of the present invention will be described below in detail with reference to the accompanying figures.
The present invention aims to provide a reliable and safe solution for battery charging, integrating fault indication, gate control, reverse current protection, and overcurrent detection into a single circuit. This solution allows for efficient and controlled charging while protecting both the charger and the battery from potential damage.
In the present invention, when a charger is connected to an external power source, and no faults are present i.e. in normal conditions, a main semiconductor switch (SW1) is turned on by a gate control circuit 200, allowing the current to flow. Current flows from the charger through the main semiconductor switch (SW1) and into a battery, charging it. The detection diode (D6) detects short-circuit and reverse polarity to cause the gate-control circuit (200) to turn OFF the main semiconductor switch (SW1). The main semiconductor switch (SW1) which is controlled by the gate control circuit (200), ensures that only the required amount of current flows to the battery. In the event of a fault or in abnormal condition, the main semiconductor switch (SW1) is turned OFF, disconnecting the battery and charger, preventing further current flow and ensuring safety.
Referring to figure 1, an integrated circuit (100) for reverse polarity and short-circuit protection in battery charging systems is shown. The integrated circuit (100) comprises the main semiconductor switch (SW1), the detection diode (D6), a short-circuit current trip element (R19), the gate control circuit (200) and a fault indication circuit (300). The main semiconductor switch (SW1) is an element which allows or blocks current flow based on a signal from the gate control circuit (200). The main semiconductor switch (SW1) is a critical component in a current flow path, enabling the current flow from the charger to the battery in normal operating conditions. In abnormal conditions, the main semiconductor switch (SW1) disconnects the charger and the battery preventing the current flow. In one embodiment of the present invention, the main semiconductor switch (SW1) is a power MOSFET which is activated by the gate control circuit (200), wherein the gate control circuit (200) is explained in detail in later paragraphs. However, the main semiconductor switch (SW1) can be any power semiconductor. When the said MOSFET is activated, it allows charging current to flow through the integrated circuit (100) and into the battery. MOSFET is specifically selected to handle the charging current without significant power loss and to provide low resistance when it is fully activated. This will ensure that the integrated circuit (100) delivers the necessary charging current efficiently while providing a means to quickly disconnect the battery in the event of a fault, a short-circuit condition or any abnormal condition. In one embodiment of the present invention, upon the occurrence of a short-circuit condition, a short-circuit current trip element (R19) and diode (D6) turns OFF the main semiconductor switch (SW1). The short-circuit trip element (R19) may be a resistor, a Zener diode, a TVS diode or a series of p-n junction diodes.
Further, the detection diode (D6) is placed in series of the short-circuit trip element (R19) allowing detection of short-circuit and reverse polarity of the battery. In one embodiment of the present invention, the detection diode (D6) is forward biased in nominal conditions, where the voltage at its anode (Positive terminal) is insufficient to cause the gate control circuit (200) to turn OFF the main semiconductor switch (SW1). The detection diode (D6) serves as a trigger element to initiate turn-off of the main semiconductor switch (SW1) via its gate-control circuitry, preventing current from flowing back from the battery to the charger, which could potentially damage the charger or drain the battery. When the main semiconductor switch (SW1) is ON, current flows through the main semiconductor switch (SW1) into the battery. In case of reverse polarity, the detection diode (D6) becomes reverse biased, and the gate control circuit (200) is activated to turn OFF the main semiconductor switch (SW1). For example, if a reverse current condition occurs i.e. if the charger and battery are connected improperly (positive and negative terminals are interchanged), the detection diode (D6) blocks the reverse flow causing its anode to be pulled up to charger voltage with respect to the negative terminal of the charger, thereby protecting the charger circuit and preventing unintended power drain from the battery. Furthermore, in case of short-circuit condition, a sudden spike in current flows through the main semiconductor switch (SW1). This causes the detection diode (D6)’s anode (positive terminal) voltage to rise, which triggers the gate control circuit (200) to turn OFF the main semiconductor switch (SW1).
Furthermore, the short-circuit current trip element (R19) is discussed in detail below. The short-circuit current trip element (R19) mainly turns OFF the main semiconductor switch (SW1) upon detecting a short-circuit event. Basically, the short-circuit current trip element (R19) is provided to detect an overcurrent or short-circuit condition and it is configured to trip (turns off) the main semiconductor switch SW1 if the current exceeds a preset limit, protecting the battery and the charger from damage. In one embodiment, the short-circuit current trip element (R19) is a resistor wherein it may also be a Zener diode or a TVS diode of a specific breakdown voltage rating and it may also be a series of p-n junction diodes. The circuitry is set up such that when the short-circuit current reaches a certain level, the voltage at the detection diode (D6) is high enough to activate the gate control circuit (200) and switch OFF the main semiconductor switch (SW1). This ensures that if an overcurrent or short-circuit condition is detected, the integrated circuit (100) automatically interrupts the charging process to protect the battery, charger and other components. During normal operation, the voltage across the short-circuit current trip element (R19) remains low. If a short-circuit or overcurrent condition occurs, the voltage across the short-circuit current trip element (R19) rises, creating a signal that triggers the gate control circuit (200) to deactivate the main semiconductor switch (SW1). This turns OFF the main semiconductor switch (SW1), immediately stopping current flow and protecting the integrated circuit (100) from potential damage due to the overcurrent condition. In one embodiment, the voltage value for the short-circuit current trip element (R19) is predefined appropriately which ensures that the integrated circuit (100) responds quickly to the abnormal currents.
Referring to figure 2, a gate control circuit (200) of a proposed integrated circuit (100) is depicted. The gate control circuit (200) serves as the central control mechanism for managing the operation of the main semiconductor switch (SW1), which regulates current flow from the charger to the battery. In one embodiment of the present invention, the gate control circuit (200) is designed such that any device with positive gate voltage threshold with respect to the charger negative terminal may be used, wherein such device may be n-IGBT, NPN transistor, N-MOS transistor or likewise. The gate control circuit (200) ensures that the main semiconductor switch (SW1) is only activated under safe conditions, preventing unintended current flow. The gate control circuit (200) comprises a P-MOS transistor (Q3), a N-MOS transistor (Q4), resistors (R8, R10, R12, R14, R15, R16, R17), Zener diodes (D5, D7, D8) and capacitor (C2). The P-MOS transistor (Q3) is configured to activate the N-MOS transistor (Q4) upon detecting a sufficient voltage based on the short-circuit trip element (R19). The N-MOS transistor (Q4) configured to turn OFF the main semiconductor switch (SW1) by pulling the gate-source voltage low during operation. The resistor (R8) is configured to limit and regulate the current through the gate control circuit (200) during operation. The resistors (R10, R17) and capacitor (C2) are configured to form a bias circuit to provide stability to the gate control circuit (200) and enable initial excitation of the main semiconductor switch (SW1), wherein the capacitor (C2) facilitates the turn ON process of the main semiconductor switch (SW1). The resistor (R12) is configured as gate resistor for the main semiconductor switch (SW1), the resistor (R14) is configured as gate resistor for the N-MOS transistor (Q4) and the resistor (R15) is configured as gate resistor for P-MOS transistor (Q3) i.e. the afore-mentioned gate resistors are to limit gate currents into the respective semiconductors. Further, the resistor (R16) is configured as a pull-down resistor for the N-MOS transistor (Q4), wherein this resistor (R16) allows initial condition of the gate voltage of the N-MOS transistor (Q4) to be zero. The Zener diodes (D5, D7, D8) are configured to protect the P-MOS transistor (Q3), N-MOS transistor (Q4), resistor (R8), and the bias circuit comprising resistors (R10, R17) and capacitor (C2) by limiting the voltages. In this, the diode (D5) protects the gate of the main semiconductor switch (SW1) from reverse voltage, preventing unwanted activation or potential damage. Furthermore, when the charger is connected, the P-MOS transistor (Q3) regulates the voltage and current supplied to the gate of the main semiconductor switch (SW1). By controlling the main semiconductor switch (SW1)’s gate with a stable voltage, the gate control circuit (200) enables the main semiconductor switch (SW1) to handle large current loads without risk of instability or unintentional switching. The transistors (Q3 & Q4) of the present embodiment are not limited to a P-MOS or an N-MOS transistor but are selected from one of the P-MOS, the N-MOS, a PNP, an NPN or transistors of equivalent type.
Referring to figure 3, the fault indication circuit (300) of the present invention is depicted. In one embodiment, the fault indication circuit (300) is used to warn the user about the fault in the integrated circuit (100), however, the fault indication circuit (300) is optional circuit and may not be used in combination with other above-mentioned circuits. The fault indication circuit (300) basically provides a visual warning to the user in case of any fault including the overcurrent situation, short-circuit event, reverse polarity event, any component failure or any abnormality in the integrated circuit (100). The fault indication circuit (300) comprises a diode (D4) or LED (D4), a transistor (Q5), resistors (R11), (R13) and (R18). The resistor (R11) is connected in series with the LED (D4) to limit the current passing through it, preventing it from burning out while operating at its rated voltage. The resistors (R13) and (R18) are part of the gate circuit for the enabling N-MOS transistor (Q5). When a fault condition occurs, such as a short-circuit, overcurrent condition or any abnormal condition, a signal is generated to light up (D4) and the LED (D4) is activated, alerting the user to the presence of a fault in the integrated charging circuit (100). The LED (D4) is powered through the current-limiting resistor (R11) and transistor (Q5) which itself is triggered through (R13) and (R18).
The N-MOS and P-MOS transistors (Q3, Q4, Q5) utilized in the present embodiment may be substituted with equivalent semiconductor devices known in the art. For example, the N-MOS transistor may be replaced by, but is not limited to, an n-channel IGBT or an NPN bipolar junction transistor. Similarly, the P-MOS transistor may be replaced by, but is not limited to, a PNP bipolar junction transistor or other equivalent devices exhibiting similar electrical characteristics. While specific language has been used to describe the invention, any limitations arising on account of the same are not intended. As would be apparent to a person skilled in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein.
FURTHER ADVANTAGES OF THE INVENTION
The integrated circuit of the present invention provides several features. It’s main function is to protect the battery charging systems from reverse polarity and short-circuit condition through a single circuit. The gate control circuit of the integrated circuit ensures stable and controlled activation of the main semiconductor switch, allowing safe and efficient current flow to the battery. The detection diode protects the charger from reverse current, essential for applications where the charger may frequently disconnect. The short-circuit current trip element prevents excessive current from damaging the battery and charger, providing a robust safety feature for overcurrent protection. The fault indication circuit provides immediate visual feedback, alerting the user to any detected faults. The proposed circuit integrates multiple safety and control features, making it highly suitable for applications where battery protection, efficient charging, and fault tolerance are critical. The proposed integrated circuit is self-powered. It doesn’t require isolation, microcontrollers, DSPs, or any additional sensing circuits. The input and output are handled using just two power lines, keeping things simple. The proposed system has low component count, it is cost-effective, less complex, and takes up minimal space on the PCB. It can also be adjusted to respond to specific short-circuit current levels and is capable of protecting against short circuits that are already present or happen during operation. Furthermore, the proposed integrated circuit can be used in battery chargers including on-board, off-board, vehicular, home-energy systems. It can also be used in any DC-DC converter.

REFERENCES
Sr. No.
Part Name
Reference Number
1
Integrated Circuit
100
2
Gate Control Circuit
200
3
Fault Indication Circuit
300
4
Resistors
R8, R10, R12, R 14, R 15, R16, R17, R18
5
Short-Circuit Current Trip Element
R19
6
Main Semiconductor Switch
SW1
7
Diodes
D5, D7, D8
8
Detection Diode
D6
9
P-MOS Transistor
Q3
10
N-MOS Transistor
Q4 , Claims:We Claim:
1.
An integrated circuit (100) for reverse polarity and short-circuit protection in battery charging systems, a circuit (100) comprising:
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a main semiconductor switch (SW1) configured to enable power transfer from a charger to a battery under normal operating conditions and to disconnect the charger and the battery during abnormal conditions to prevent current flow;
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a detection diode (D6) configured to monitor voltage levels across the said circuit (100) and control the main semiconductor switch (SW1);
-
a short-circuit current trip element (R19) configured to turn OFF the main semiconductor switch (SW1) upon detecting a short-circuit event;
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a gate control circuit (200) comprises of one or more switches, one or more resistors (R8, R10, R12, R14, R15, R16, R17, R18) and one or more diodes (D5, D7, D8) configured to control ON and OFF states of the main semiconductor switch (SW1) based on predefined circuit conditions; and
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a fault indication circuit (300) configured to indicate presence of fault within the system and provide a warning or alert when abnormal conditions are detected.
2.
The circuit as claimed in claim 1, wherein the gate control circuit (200) comprises:
a transistor (Q3) configured to activate transistor (Q4) upon detecting a sufficient voltage based on the short-circuit trip element (+-R19) and the detection diode (D6);
the transistor (Q4) configured to turn OFF the main semiconductor switch (SW1) by pulling the gate-source voltage low during operation;
a resistor (R8) configured to limit and regulate the current through the gate control circuit (200) during operation;
resistors (R10, R17) and capacitor (C2) configured to form a bias circuit to provide stability to the gate control circuit (200) and enable initial excitation of the main semiconductor switch (SW1), wherein the capacitor (C2) facilitates the turn ON process of the main semiconductor switch (SW1); and
Zener diodes (D5, D7, D8) configured to protect the transistor (Q3), transistor (Q4), and the main semiconductor switch (SW1).
3.
The circuit as claimed in claim 1, wherein the main semiconductor switch (SW1) is a device configured to operate with a positive gate voltage threshold relative to the charger’s negative terminal.
4.
The circuit as claimed in claim 1, wherein the detection diode (D6) is configured to be forward biased in nominal conditions and the voltage at its anode is insufficient to cause the gate control circuit (200) to turn OFF the main semiconductor switch (SW1).
5.
The circuit as claimed in claim 1, wherein the detection diode (D6) is configured to be reverse biased during a reverse polarity event, causing the anode voltage of the detection diode (D6) to rise above a predefined threshold, thereby activating the gate control circuit (200) to turn OFF the main semiconductor switch (SW1).
6.
The circuit as claimed in claim 1, wherein the detection diode (D6) is configured such that the anode voltage rises during the short-circuit event, triggering the gate control circuit (200) to turn OFF the main semiconductor switch (SW1).
7.
The circuit as claimed in claim 1, wherein the transistor (Q3) and the transistor (Q4) are selected from one of a P-MOS, an N-MOS, a PNP, an NPN or transistors of equivalent type.
8.
The circuit as claimed in claim 1, wherein the short circuit current trip element (R19) is selected from one of a resistor, a Zener, a TVS diode of a specific breakdown voltage rating, or a series of p-n junction diodes.
9.
The circuit as claimed in claim 1, wherein the fault indication circuit (300) comprises an LED indicator or an audio alarm configured to provide a visual or audible alert when an abnormal condition is detected.
10.
The circuit as claimed in claim 1, wherein the main semiconductor switch (SW1) is configured to be a MOSFET selected from the group consisting of an N-channel MOSFET, a P-channel MOSFET N-channel IGBT or equivalent type transistors depending on circuit polarity requirements.
11.
The circuit as claimed in claim 1, wherein the circuit is powered by either the battery voltage or the charger output voltage, and is configured to operate as a self-contained unit, requiring no intervention from a microcontroller, external circuitry, or software.