Protection circuit of low-voltage circuit, electronic equipment and vehicle

Abstract

The invention relates to a protection circuit of a low-voltage circuit, electronic equipment and a vehicle, and the protection circuit is connected between a low-voltage power supply end of a low-voltage working circuit and a protected circuit, and carries out the state switching of the protected circuit according to the voltage change of the low-voltage power supply end. Wherein the voltage change is generated under the condition that a high-voltage power supply end of a high-voltage working circuit is electrically coupled to the low-voltage power supply end. According to the technical scheme, the state switching of the protected circuit is automatically triggered on the basis of capturing the voltage change on the low-voltage power supply end and generated under the condition that the high-voltage power supply end of the high-voltage working circuit is electrically coupled to the low-voltage power supply end in real time, so that the normal working condition and the risk scene are intelligently distinguished; safe operation of a low-voltage circuit in a complex high-voltage environment is ensured, and system reliability and service life are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrical protection, in particular to a protection circuit of a low-voltage circuit, an electronic device and a vehicle. BACKGROUND

[0002] As a low-voltage working circuit in a motor system, the Hall sensor adopts compatible 5V-16V low-voltage power supply (limited by the lagging development of vehicle devices), and if the driving voltage of the brush motor rises to 16V or above, it will cause the risk of coexistence of high-voltage and low-voltage wiring harnesses: the internal space of the motor is compact, and the high-voltage driving wiring harness (M+ / M-) and the low-voltage power supply end wiring harness (HALL+ / HALL-) are prone to physical short circuit.

[0003] The traditional overvoltage protection adopts discrete device combination (such as triode, MOS tube, ESD), wherein, the multi-device layout is complex and occupies a large area; when the positive electrode of the low-voltage power supply end is short-circuited to M- and the negative electrode is short-circuited to M+, the current forms a path through the MOS body diode, which can break the protection device; more importantly, when the protected circuit is short-circuited, there is a lack of current limiting mechanism, which can cause thermal runaway of the protection circuit. SUMMARY

[0004] The embodiments of the present application provide a protection circuit of a low-voltage circuit, an electronic device and a vehicle, which can realize a high-integration protection circuit in a limited space and avoid the risk of ablation, so as to at least partially solve the above technical problems.

[0005] In order to achieve the above-mentioned purpose, according to the first aspect of the present application, a protection circuit of a low-voltage circuit is provided, which is connected between a low-voltage power supply end of a low-voltage working circuit and a protected circuit, and performs state switching of the protected circuit according to voltage change of the low-voltage power supply end; wherein, the voltage change is caused by the case that a high-voltage power supply end of a high-voltage working circuit is electrically coupled to the low-voltage power supply end.

[0006] Optionally, comprising:

[0007] A voltage response unit connected with the low-voltage power supply end, for detecting voltage change of the low-voltage power supply end and generating a state trigger signal;

[0008] Wherein, the voltage change contains at least one of the following abnormal types: voltage amplitude exceeding a preset voltage threshold, voltage polarity reversal.

[0009] Optionally, the voltage response unit comprises:

[0010] A protection control circuit connected with the low-voltage power supply end signal, for detecting the voltage amplitude of the low-voltage power supply end and generating an overvoltage trigger signal when the voltage amplitude exceeds the preset voltage threshold.

[0011] Optionally, the voltage response unit includes:

[0012] The polarity response circuit is connected to the low-voltage power supply terminal and is used to output a corresponding path state signal according to the power supply polarity of the power supply path of the protected circuit.

[0013] Optionally, the voltage response unit includes:

[0014] The transient suppression circuit is connected in parallel between the low-voltage power supply terminal and the protection control circuit, and is used to suppress the transmission of power-on transient voltage and output a transient suppression signal.

[0015] Optionally include:

[0016] A protection execution unit is connected to the voltage response unit. When the voltage changes to a value exceeding a preset voltage threshold, the protection execution unit is configured to respond to the state trigger signal and cut off the power supply path of the protected circuit.

[0017] Optionally include:

[0018] A protection execution unit is connected to the voltage response unit. When the voltage change is a voltage polarity reversal, the protection execution unit is used to respond to the state trigger signal and perform dynamic current constraint on the protected circuit.

[0019] Optionally, the protection control circuit includes: the protection control circuit includes a voltage regulator and a first resistor, the cathode of the voltage regulator is connected to the low-voltage power supply end through the first resistor, and the anode is connected to the power supply end ground of the low-voltage working circuit.

[0020] Optionally, the polarity response circuit includes a Schottky diode, an anode of the Schottky diode is connected to the low-voltage power supply end, and a cathode of the Schottky diode is connected to the power supply control node of the protection execution unit.

[0021] Optionally, the protection execution unit includes a first PNP transistor and a second PNP transistor connected in cascade;

[0022] The emitter of the first PNP transistor is connected to the cathode of the Schottky diode, and the collector is connected to the protected circuit;

[0023] The base of the second PNP transistor receives the state trigger signal, and the collector is connected to the base of the first PNP transistor;

[0024] The emitters of the first PNP transistor and the second PNP transistor are commonly connected to the low-voltage power supply end.

[0025] Optionally, the overvoltage trigger signal is input into the base of the second PNP transistor;

[0026] The path state signal directly controls the emitter bias of the first PNP transistor;

[0027] The protection execution unit generates the state trigger signal through the logic combination of the first PNP transistor and the second PNP transistor.

[0028] Optionally, the transient suppression circuit includes a capacitor and a second resistor, one end of the capacitor is grounded via the second resistor, and the other end is connected to the low-voltage power supply end.

[0029] Optionally, the transient suppression circuit controls the attenuation duration of the transient suppression signal through an RC time constant.

[0030] Optionally, it also includes:

[0031] a current detection resistor connected in series between the emitter of the first PNP transistor and the low-voltage power supply terminal, for real-time monitoring of the output current;

[0032] When the voltage drop across the current detection resistor exceeds a preset voltage drop threshold, the second PNP transistor is triggered to turn on and the first PNP transistor is turned off.

[0033] Optionally, it also includes:

[0034] The feedback resistor is connected between the base of the second PNP transistor and the emitter of the first PNP transistor.

[0035] Optionally, the low-voltage operating circuit is a Hall sensor power supply circuit in the motor system.

[0036] Optionally, the operating voltage range of the power supply end of the low-voltage working circuit is 5V to 16V.

[0037] Optionally, the high-voltage working circuit is a motor drive circuit in a motor system.

[0038] Optionally, the operating voltage range of the high-voltage operating circuit is 42V to 56V.

[0039] According to a second aspect of the present application, an electronic device is provided, comprising the protection circuit for the low-voltage circuit according to any one of the embodiments of the present application.

[0040] According to a third aspect of the present application, a vehicle is also provided, comprising the protection circuit for the low-voltage circuit as described in any one of the embodiments of the present application, or the electronic device provided in the embodiments of the present application.

[0041] To sum up, the embodiments of the present application, through the above-mentioned technical solution, automatically trigger the state switching of the protected circuit by capturing in real time the voltage changes on the low-voltage power supply end of the low-voltage working circuit when the high-voltage power supply end of the high-voltage working circuit is electrically coupled to the low-voltage power supply end, and intelligently distinguish between normal working conditions and risk scenarios. At the moment an abnormality occurs, the power supply path is cut off and the dangerous current path is physically isolated, thereby preventing electrical overstress from damaging the protected circuit at the root, reducing space occupancy, improving response speed, realizing accurate detection, dynamic response and failure isolation, ensuring the safe operation of low-voltage circuits in complex high-voltage environments, and improving system reliability and service life.

[0042] Other features and advantages of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] To more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present application. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0044] In order to more completely understand the present application and its beneficial effects, the following description will be given in conjunction with the accompanying drawings, wherein the same drawing numbers represent the same parts in the following description.

[0045] Figure 1 This is a schematic diagram of the connection relationship between the high and low voltage wiring harnesses of a brushed motor provided in an exemplary embodiment of the present application;

[0046] Figure 2 1 is a schematic diagram of the voltage difference detection and protection execution connection of the brushed motor low-voltage protection circuit provided in an exemplary embodiment of the present application;

[0047] Figure 3 1 is a schematic diagram of a module architecture of a protection circuit for a low-voltage circuit of a brushed motor provided in an exemplary embodiment of the present application;

[0048] Figure 4 1 is a schematic diagram of a module architecture of a voltage response circuit of a low-voltage circuit of a brushed motor provided in an exemplary embodiment of the present application;

[0049] Figure 5 This is a specific implementation principle diagram of a protection circuit for a low-voltage circuit of a brushed motor provided in an exemplary embodiment of the present application;

[0050] Figure 6 Schematic diagram of the vehicle structure provided in an exemplary embodiment of the present application.

[0051] Description of reference numerals:

[0052] 11. External power supply system; 12. Motor assembly; 13. Protection circuit; 14. Protected circuit;

[0053] 23. Protection circuit; 231. Voltage response unit; 232. Protection execution unit; 24. Protected circuit;

[0054] 33. Protection circuit; 331. Voltage response unit; 3310. Protection control circuit; 3311. Transient suppression circuit; 3312. Polarity response circuit; 34. Protected circuit;

[0055] 40. Vehicle. DETAILED DESCRIPTION

[0056] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0057] Based on the problems mentioned in the above background technology, in the 48V high-voltage platform brushed motor system, in order to overcome the risk of ablation caused by short circuit between the low-voltage Hall circuit and the high-voltage drive harness, in related technologies, a multi-stage discrete device combination overvoltage protection architecture (such as transistor + MOS tube + ESD) is generally adopted to realize the overvoltage cut-off function of the Hall circuit, thereby avoiding high voltage directly loading to the low-voltage device. However, in order to cover the complex short-circuit conditions under the 48V platform (such as reverse polarity short circuit and internal circuit short circuit), additional functional modules need to be superimposed, which leads to the following technical problems: the multi-device layout leads to an increase in circuit area, which violates the space constraints of the brushed motor cavity and increases the procurement cost of discrete components; when a cross short circuit occurs, where the positive pole of the Hall power supply is short-circuited to the negative pole of the motor (M-) and the negative pole of the Hall power supply is short-circuited to the positive pole of the motor (M+), the current forms a path through the MOS tube body diode, and the reverse high voltage breaks down the BE junction of the transistor, causing damage to the protection circuit itself; when the protected circuit (Hall signal acquisition circuit) is internally short-circuited, without a current-limiting resistor design, the protection circuit continues to output a large current, causing self-corrosion, resulting in a secondary fault.

[0058] This shows that while existing technologies offer some feasibility in providing basic overvoltage protection, this protection comes at the expense of system reliability, increased hardware redundancy, and amplified thermal runaway risks. Their fundamental flaw lies in their reliance on stacked components to achieve a single function, rather than integrating multi-condition protection requirements through architectural innovation. This leads to core requirements such as space usage, reverse polarity blocking, and self-protection mechanisms being mutually constrained, ultimately weakening the protection effectiveness due to system fragility.

[0059] Precisely to solve the above-mentioned problems, some embodiments of the present application provide an overvoltage protection circuit based on a dual PNP transistor collaborative architecture, which not only reduces the number of devices and space occupancy, but also ensures the self-protection capability of the protection circuit in complex failure modes through innovative elements such as Schottky diodes and current-limiting resistors.

[0060] This application provides an overvoltage protection circuit, please refer to Figure 1 and Figure 2 .in, Figure 1 This is a schematic diagram of the connection relationship between the high and low voltage wiring harnesses of a brushed motor provided in an exemplary embodiment of the present application. Figure 2 1 is a schematic diagram of the voltage difference detection and protection execution connection of the brushed motor low-voltage protection circuit provided in an exemplary embodiment of the present application.

[0061] The protection circuit is connected between the low-voltage power supply end of the low-voltage working circuit and the protected circuit, and performs state switching of the protected circuit according to the voltage change of the low-voltage power supply end; wherein, the voltage change is generated when the high-voltage power supply end of the high-voltage working circuit is electrically coupled to the low-voltage power supply end.

[0062] The protection circuit senses the voltage changes on the low-voltage power supply end caused by the electrical coupling of the high-voltage power supply end of the high-voltage working circuit to the low-voltage power supply end, and executes a corresponding protection strategy for the protected circuit. It replaces the multi-stage discrete detection circuit through integrated sensing, reduces space occupancy, and indicates the protection success rate.

[0063] Among them, the low-voltage working circuit and the high-voltage working circuit refer to the working voltage of the low-voltage working circuit being lower than the working voltage of the high-voltage working circuit, that is, the highest value of the working voltage range of the low-voltage working circuit is lower than the lowest value of the working voltage range of the high-voltage working circuit; the lowest value of the working voltage range of the high-voltage working circuit is higher than the highest value of the working voltage range of the low-voltage working circuit.

[0064] In some embodiments, the low-voltage operating circuit is a Hall sensor power supply circuit in a motor system.

[0065] Specifically, the operating voltage of the Hall sensor power supply circuit is 5V to 16V. Optionally, the low voltage supply voltage of the Hall sensor power supply circuit is 5V, 8V, 12V, or 16V.

[0066] In some embodiments, the high-voltage operating circuit is a motor drive circuit in a motor system.

[0067] Specifically, the high-voltage supply voltage of the high-voltage working circuit is 48V.

[0068] like Figure 1As shown, for example, the external power supply system 11 is connected to the motor assembly 12 via four wiring harnesses. Wiring harness 1 and wiring harness 2 are connected to the motor drive high-voltage positive electrode (M+) and negative electrode (M-), respectively, carrying the 48V platform drive voltage (42V-56V); wiring harness 3 and wiring harness 4 are connected to the low-voltage Hall power supply positive electrode (HALL+ / SIGNAL) and ground terminal (HALL- / GND), respectively, providing working power for the low-voltage Hall circuit (typical value 5V-16V). The motor assembly 12 integrates a protection circuit 13 and a protected circuit 14.

[0069] Protection circuit 13, connected across wiring harness 3 (the low-voltage Hall effect power supply) and wiring harness 4, monitors the voltage difference and polarity changes between wiring harnesses 3 and 4 in real time. If overvoltage, reverse polarity, or a short circuit in the signal acquisition circuit is detected, the power supply path is cut off or isolated to prevent thermal failure of the acquisition circuit.

[0070] The protected circuit 14 is used to convert the collected rotor position magnetic field signal into an electrical pulse, and its power supply terminal (VIN) is input by the wiring harness 3, and the ground terminal (GND) is connected by the wiring harness 4.

[0071] For example, the protected circuit 14 is a Hall sensor power supply circuit, and the protection circuit 13 is used to protect the Hall sensor power supply circuit. The Hall sensor power supply circuit is connected to the Hall sensor to collect the rotor position magnetic field signal.

[0072] When an abnormal short circuit occurs between the harnesses, for example, harness 1 (M+) and harness 3 (HALL+) are short-circuited, the 48V high voltage will be directly injected into the low-voltage Hall power supply end, and the voltage difference will increase significantly at this time; if harness 1 (M+) and harness 4 (HALL- / GND) are short-circuited, and harness 2 (M-) and harness 3 (HALL+) are short-circuited at the same time, a reverse polarity condition will be formed, and the power supply polarity will be reversed. The protection circuit 13 triggers the corresponding protection mechanism by continuously comparing the amplitude and polarity relationship of the two voltages: cutting off the power supply to the protected circuit 14 in the event of overvoltage, physically isolating the current path in the event of reverse polarity, and restricting the output current when the protected circuit 14 itself is short-circuited, thereby avoiding low-voltage circuit ablation. The specific working principle will be described in detail below.

[0073] It's understandable that when high- and low-voltage wiring harnesses are arranged in parallel within a confined space, insulation failure could cause high voltage to leak into the low-voltage circuit. Protection circuit 13 addresses this short-circuit risk by utilizing the electrical isolation between the high- and low-voltage circuits—namely, the absence of a common ground connection between the motor drive voltage terminal and the low-voltage Hall effect power supply terminal—to enable voltage difference and polarity detection.

[0074] Figure 3 Schematic diagram of a module architecture of a protection circuit for a low-voltage circuit of a brushed motor provided in an exemplary embodiment of the present application.

[0075] The protection circuit 23 includes:

[0076] The voltage response unit 31 is connected to the low-voltage power supply end and is used to detect the voltage change of the low-voltage power supply end and generate a state trigger signal.

[0077] The voltage change includes at least one of the following abnormal types: a voltage amplitude exceeding a preset voltage threshold, and a voltage polarity reversal.

[0078] The protection execution unit 232 is connected to the voltage response unit 231 and is used to respond to the state trigger signal to perform controlled on-off and reverse polarity path isolation of the power supply path of the protected circuit, as well as dynamic current constraint when the protected circuit itself is short-circuited.

[0079] In some embodiments, when the voltage change is a voltage polarity reversal, the protection execution unit 232 is configured to respond to the state trigger signal and perform dynamic current constraint on the protected circuit.

[0080] In some embodiments, when the voltage change is a case where the voltage amplitude exceeds a preset voltage threshold, the protection execution unit 232 is configured to respond to the status trigger signal and cut off the power supply path of the protected circuit.

[0081] The protection circuit 23 is integrated inside the motor assembly, located between the low-voltage power supply end (receiving external 5V-16V input) and the protected circuit 24 (Hall sensor power supply circuit), and detects the potential information of the motor drive voltage end (42V-56V high-voltage source) in real time. By dynamically sensing the risk of abnormal mutual interference between the high / low voltage wiring harnesses, it realizes full-condition protection of the low-voltage circuit, especially for the high and low voltage coexistence scenario unique to the 48V platform.

[0082] Specifically, the voltage response unit 231 continuously detects the real-time voltage amplitude of the low-voltage power supply end and the ground end. When the high-voltage wiring harness (such as M+) is accidentally short-circuited to the low-voltage wiring harness (such as HALL+), the voltage difference suddenly increases to above the preset voltage threshold (such as the voltage regulation value of the voltage regulator tube 30V), triggering the overvoltage protection signal; monitoring the potential gradient direction of the power supply path (such as the negative voltage difference between HALL+ and M-), identifying the reverse polarity short circuit condition (such as HALL+ short-circuiting M- and HALL- short-circuiting M+); and filtering out transient voltage spikes (such as ≤200ms) caused by motor start-stop and electromagnetic compatibility (EMC) noise to avoid false triggering. After real-time analysis of the above electrical parameters, three types of key state trigger signals are output, namely, overvoltage trigger signal (voltage amplitude > voltage threshold), reverse polarity lock signal (abnormally reversed potential gradient) and steady-state enable signal (valid state after transient interference filtering).

[0083] The protection execution unit 232 is used to cut off the low-voltage power supply (HALL+ switches to VOUT) upon receiving an overvoltage trigger signal or a reverse polarity signal, activate the reverse polarity lock signal to physically block the reverse current loop, and limit the output current by short-circuiting the internal protected circuit to avoid thermal runaway.

[0084] In the reverse polarity short circuit scenario, the protection execution unit 232 first cuts off the power supply path (to prevent positive current shock) and simultaneously activates physical blocking (to prevent reverse leakage current) to form bidirectional isolation.

[0085] When the protected circuit 24 itself is short-circuited, the protection execution unit 232 dynamically adjusts the on-resistance (eg, increases the equivalent resistance) according to current feedback to limit the output power within a safety threshold.

[0086] Figure 4 Schematic diagram of the module architecture of a voltage response circuit of a low-voltage circuit of a brushed motor provided in an exemplary embodiment of the present application.

[0087] In some embodiments, the voltage response unit 331 includes: a protection control circuit 3310, which is connected to the low-voltage power supply end signal, used to detect the voltage amplitude of the low-voltage power supply end, and generate an overvoltage trigger signal when the voltage amplitude exceeds a preset voltage threshold.

[0088] In some embodiments, the voltage response unit 331 includes a transient suppression circuit 3311 connected in parallel between the low-voltage power supply terminal and the protection control circuit 3310 for suppressing the transmission of power-on transient voltage and outputting a transient suppression signal.

[0089] In some embodiments, the voltage response unit 331 includes: a polarity response circuit 3312 connected in series between the low-voltage power supply end and the protection execution unit 332, for outputting a corresponding path status signal according to the power supply polarity of the power supply path of the protected circuit 34.

[0090] It can be understood that the voltage response unit 331 includes at least one of a protection control circuit 3310, a transient suppression circuit 3311, and a polarity response circuit 3312 to detect the voltage change of the low-voltage power supply end and generate a corresponding status trigger signal.

[0091] Accordingly, the state trigger signal is generated by coupling at least one of the overvoltage trigger signal, the transient suppression signal, and the path state signal.

[0092] In some embodiments, the voltage response unit 331 includes a protection control circuit 3310, a transient suppression circuit 3311, and a polarity response circuit 3312. The state trigger signal is generated by logically combining the overvoltage trigger signal, the transient suppression signal, and the path state signal.

[0093] Specifically, the overvoltage trigger signal is active when the voltage difference exceeds a threshold value; the transient suppression signal is active at the initial stage of power-on and decays over time; the pass state signal is in an on state when the supply polarity is normal and in an off state when the polarity is reversed.

[0094] The protection control circuit 3310 continuously monitors the voltage amplitude between the low-voltage supply end and the ground end. When the high-voltage harness accidentally invades the low-voltage circuit (for example, a short circuit between M+ and HALL+ causes a sudden 48V voltage difference), it captures abnormal deviations exceeding the voltage threshold (such as 16V) and generates an overvoltage trigger signal. The protection control circuit 3310 identifies positive high-voltage invasion (such as HALL+ connecting to M+) and also detects abnormal reverse polarity potential (such as a negative voltage difference formed when HALL+ connects to M-). The threshold value is dynamically adjusted according to the Hall supply rated value to avoid false triggering in 12V / 5V compatible scenarios.

[0095] The transient suppression circuit 3311 absorbs transient fluctuations with a duration less than a threshold value (such as 5 milliseconds) through a specific time constant (such as an RC delay). For example, voltage oscillations that may occur at the initial stage of power-on are smoothed by this circuit. Only when the abnormal voltage lasts for more than the critical duration does it output an effective transient suppression signal, reducing the false triggering rate.

[0096] The polarity response circuit 3312 analyzes the direction of charge movement in real time. When it detects reverse current flow (such as reverse electron migration caused by reverse polarity short circuit), it immediately locks the abnormal polarity state and generates a pass state signal, providing a directional basis for subsequent blocking.

[0097] In some embodiments, the overvoltage trigger signal, the transient suppression signal, and the pass state signal are coupled to generate the state trigger signal. The three signals are not simply superimposed, but are analyzed by a logic coupler for time and space correlation: only when the overvoltage signal persists, the transient interference is confirmed to be invalid, and the polarity state is abnormal, a high-confidence state trigger signal is generated.

[0098] In embodiments of the present application, the voltage response unit decouples voltage difference detection, transient interference filtering, and polarity state recognition into three parallel processing channels, transforming passive response of traditional protection circuits into active prediction type protection, forming a perception network covering all risk scenarios of the 48V platform.

[0099] Figure 5 is a specific implementation schematic diagram of a protection circuit for a brush motor low-voltage circuit provided in an exemplary embodiment of the present application.

[0100] In some embodiments, the protection control circuit includes: a voltage regulator (D1) and a first resistor (R1), the cathode of the voltage regulator (D1) is connected to the low-voltage power supply end (VIN) via the first resistor (R1), and the anode is connected to the power supply end ground of the low-voltage working circuit.

[0101] Specifically, the cathode of the voltage regulator (D1) is connected to the low-voltage power supply terminal (VIN) via the first resistor (R1), capturing voltage fluctuations at the low-voltage power supply terminal (VIN) in real time. When the low-voltage power supply terminal (VIN) suddenly increases to 48V due to a short circuit in the high-voltage wiring harness (such as M+ invading HALL+), the voltage regulator (D1) reversely breaks down and conducts (the breakdown voltage is preset to 16V). The first resistor (R1) acts as a current-limiting impedance, limiting the breakdown current to a safe range (such as ≤10mA), while generating an overvoltage trigger signal representing the voltage difference at its two ends.

[0102] In some embodiments, the transient suppression circuit includes: a capacitor (C1) and a second resistor (R4), and one end of the capacitor (C1) is grounded via the second resistor (R4).

[0103] Specifically, the transient suppression circuit forms an RC filter network with a capacitor (C1) and a second resistor (R4). One end of the capacitor (C1) is grounded via the second resistor (R4), and the other end is connected to a low-voltage power supply terminal (VIN), forming a high-pass filter characteristic to filter out transient spikes (such as motor EMC noise) with a duration of less than 5ms. The second resistor (R4) limits the charging current to prevent the capacitor (C1) from being nearly short-circuited when powered on, causing an inadvertent shutdown. The transient suppression signal at the output end (C1-R4 node) maintains a high level only under steady-state voltage and is forced to be low during transient interference.

[0104] At the initial power-on stage, the transient suppression signal at the output end (C1-R4 node) is 0, delaying the turn-on time of the protection execution unit to avoid surge shock. During normal operation, the transient suppression signal at the output end (C1-R4 node) is equal to the signal at the low-voltage Hall power supply end (VIN), keeping the circuit unobstructed.

[0105] In some embodiments, the polarity response circuit includes a Schottky diode (D2), the anode of the Schottky diode (D2) being connected to the low-voltage power supply terminal (VIN) and the cathode being connected to the power supply control node of the protection execution unit. The other end of the capacitor (C1) is connected to the low-voltage power supply terminal (VIN) via the Schottky diode (D2).

[0106] Specifically, when the circuit is in a normal power supply state, that is, when a standard operating voltage (e.g., the typical low-voltage range suitable for Hall effect sensors) is applied to the low-voltage power supply terminal (VIN), the forward voltage drop of the Schottky diode (D2) is significantly lower than that of a conventional silicon-based diode. This significantly reduces the voltage loss generated when current flows through the diode. In continuous operation, this not only avoids reliability risks caused by overheating but also reduces the overall standby energy consumption of the system. When a reverse polarity short circuit occurs (e.g., HALL+ shorts M-), the low-voltage power supply terminal (VIN) is pulled to a negative voltage, and the Schottky diode (D2) is immediately cut off, physically cutting off the reverse current path. This is something that traditional MOS solutions cannot achieve due to the body diode.

[0107] In some embodiments, the protection execution unit includes: a first PNP transistor (Q1A) and a second PNP transistor (Q1B) connected in cascade; the emitter of the first PNP transistor (Q1A) is connected to the cathode of the Schottky diode (D2), and the collector is connected to the protected circuit (VOUT); the base of the second PNP transistor (Q1B) receives the status trigger signal, and the collector is connected to the base of the first PNP transistor (Q1A); the emitters of the first PNP transistor (Q1A) and the second PNP transistor (Q1B) are commonly connected to a low-voltage power supply terminal (VIN).

[0108] Specifically, the first PNP transistor (Q1A) serves as the main power switch, with its emitter directly connected to the cathode output of the Schottky diode (D2) and its collector connected to the power supply input (VOUT) of the protected circuit. This allows the first PNP transistor (Q1A) to directly carry the entire load current of the Hall effect sensor during operation, becoming a key control node in the energy transmission path. The second PNP transistor (Q1B) has its base serving as the receiving port for the state trigger signal. Its collector forms a cascade control link with the base of the first PNP transistor (Q1A), forming a signal amplification and power drive structure.

[0109] During normal system operation, the second PNP transistor (Q1B) remains off due to the lack of a valid trigger signal. The base of the first PNP transistor (Q1A) is pulled low, turning on the emitter of the first PNP transistor (Q1A). Current flows from the low-voltage power supply (VIN) through the first PNP transistor (Q1A) to the protected circuit. When the protection mechanism is activated (e.g., due to an overvoltage or reverse polarity fault), the status trigger signal drives the second PNP transistor (Q1B) into conduction. The base potential of the first PNP transistor (Q1A) is pulled up to the voltage of the low-voltage power supply (VIN), causing the emitter of the first PNP transistor (Q1A) to turn off, completely cutting off power to the VOUT terminal.

[0110] In some embodiments, the protection control circuit includes:

[0111] A current detection resistor (R5) is connected in series between the emitter of the first PNP transistor (Q1A) and the low-voltage power supply terminal (VIN), and is used to convert the load current flowing through the first PNP transistor (Q1A) into a voltage signal in real time, and trigger an overcurrent protection action through the voltage signal.

[0112] When the voltage drop across the current detection resistor (R5) exceeds a second threshold, the second PNP transistor (Q1B) is triggered to turn on and the first PNP transistor (Q1A) is turned off.

[0113] Specifically, when a sudden internal short circuit occurs in the protected circuit, the load current surges instantly. The voltage difference across the current sensing resistor (R5) then rises significantly. When this voltage exceeds a preset threshold voltage (determined by the transistor's conduction characteristics), it directly triggers the second PNP transistor (Q1B) into a saturated conduction state. This conduction of the second PNP transistor (Q1B) causes the first PNP transistor (Q1A) to switch from on to fully off, completely severing the power supply path.

[0114] In the embodiments of the present application, the current detection resistor (R5) can effectively prevent the protected circuit from overheating and damage caused by continuous high current in a short-circuit state, thereby avoiding irreversible burning of the protected circuit (important components such as the Hall sensor); on the other hand, by real-time limiting the operating current of the first PNP transistor (Q1A), it is ensured that the power components of the protection circuit itself will not cause thermal runaway due to overload, thereby eliminating the risk of failure of the protection system itself.

[0115] In some embodiments, the protection control circuit includes:

[0116] A feedback resistor (R3) is connected between the base of the second PNP transistor (Q1B) and the first PNP transistor (Q1A) and is used to stabilize the transmission of the trigger signal.

[0117] Specifically, one end of the feedback resistor (R3) is connected to the base of the second PNP transistor (Q1B), the other end is connected to the emitter of the first PNP transistor (Q1A) via the first resistor (R1), and the other end is also connected to the cathode of the voltage regulator (D1). When the protection trigger signal drives the second PNP transistor (Q1B) into the on state, the feedback resistor (R3) quickly releases the base charge, accelerating the turn-off time of the first PNP transistor (Q1A), ensuring that the abnormal voltage is completely isolated before exceeding the safety threshold.

[0118] This disclosure exemplifies the operating principle of a protection circuit for a brushed motor's low-voltage circuit. During the initial power-up phase, when external wiring is normal, the voltage at the low-voltage Hall effect power supply terminal (VIN) charges the capacitor (C1) through a second resistor (R4). At this point, the charge across the capacitor (C1) approaches a short circuit, causing the base-emitter voltage (Vbe) of the first PNP transistor (Q1A) to approach 0 volts, immediately shutting off the first PNP transistor (Q1A). This action cuts off the power supply path to the protected circuit, effectively preventing damage to subsequent circuits from transient voltage surges.

[0119] After the system enters a stable operating state, the low-voltage Hall supply voltage (e.g., 5V or 12V) falls below the breakdown threshold of the Zener diode (D1), and the Zener diode (D1) remains in the off state. At this point, the voltage at the top of the Zener diode (D1), the base voltage of the second PNP transistor (Q1B), and the voltage at the top of the first resistor (R1) are equal and all equal to the emitter voltage of the second PNP transistor (Q1B). Since there is no voltage difference between the base and emitter of the second PNP transistor (Q1B) (Vbe = 0V), the second PNP transistor (Q1B) remains off. Simultaneously, the capacitor (C1) has completed charging, and the voltage across it is determined by the voltage divider resistor (R2), causing the base potential of the first PNP transistor (Q1A) to be lower than the emitter potential. With Vbe exceeding the conduction threshold, the first PNP transistor (Q1A) remains on, and the protected circuit receives normal power.

[0120] When the protected circuit (Hall signal acquisition circuit) experiences a sudden internal short-circuit fault, the voltage differential across the current sensing resistor (R5) rises rapidly. Once this voltage differential exceeds the conduction threshold, the additional voltage forms a drive current (Ib) through the first resistor (R1) and the feedback resistor (R3), forcing the second PNP transistor (Q1B) to conduct and enter the on state. The conduction of the second PNP transistor (Q1B) directly raises the base potential of the first PNP transistor (Q1A) to approximately the low-voltage Hall power supply terminal (VIN), causing the first PNP transistor (Q1A) to immediately shut down, thereby limiting the continued rise in short-circuit current and completely avoiding the risk of thermal runaway of the protection circuit itself.

[0121] If the positive Hall power supply wiring harness is accidentally short-circuited to the motor drive high-voltage wiring harness (e.g., 48V), the voltage at the low-voltage Hall power supply terminal (VIN) will be abnormally increased. At this point, the voltage regulator (D1) will be turned on due to the voltage exceeding the breakdown threshold, and the base-emitter of the second PNP transistor (Q1B) will be forward biased (Vbe>0.7V), turning on the second PNP transistor (Q1B). The conduction state of the second PNP transistor (Q1B) causes the base potential and emitter potential of the first PNP transistor (Q1A) to converge, instantly shutting off the first PNP transistor (Q1A), and preventing the high voltage from being transmitted to the protected circuit. During this process, the first resistor (R1) limits the operating current of the voltage regulator (D1), ensuring that the protection circuit can continuously withstand long-term short-circuit conditions.

[0122] When the negative Hall power supply wiring harness is shorted to the high-voltage motor drive wiring harness, the ground terminal (GND) becomes the high-voltage side, and the low-voltage Hall power supply terminal (VIN) switches to the low-voltage side. At this time, the Schottky diode (D2) is cut off due to the reverse voltage, completely blocking the current loop. Neither the Hall circuit nor the protection circuit is damaged.

[0123] Similarly, if the negative electrode of the Hall power supply is short-circuited to the high-voltage harness and the positive electrode is short-circuited to the low-voltage harness, the Schottky diode (D2) still maintains the reverse cutoff state and the current cannot form an effective path.

[0124] In the extreme case where the positive and negative electrodes of the Hall effect power supply are simultaneously shorted to the high-voltage or low-voltage wiring harness of the motor drive, the potential difference across the protection circuit approaches zero. In this case, the first PNP transistor (Q1A) and the second PNP transistor (Q1B) remain off due to the lack of drive voltage. No current flows through the downstream circuit, and the protection circuit itself enters a safe dormant state.

[0125] It should be noted that the brushed motor low-voltage circuit protection circuit in the embodiments of this application provides safety protection for the brushed motor's internal low-voltage Hall effect circuit, preventing damage to the protected circuit if the protected circuit is damaged. However, it does not protect the motor's external circuits or the preceding control circuits. All protection actions are automatically triggered by analog circuitry, enabling rapid response to short-circuit conditions without software intervention.

[0126] For example, when the Hall power supply is 12V and the motor drive voltage is 48V, the voltage difference reaches 36V, and the protection circuit automatically responds through a specific structure. In this scenario, the low-voltage Hall power supply terminal (VIN) is connected to a 12V power supply, while the motor drive terminal (M+) is 48V. If M+ is accidentally shorted to HALL+, the voltage difference suddenly increases to 36V, exceeding the preset threshold (e.g., 18V) of the Zener diode (D1). The Zener diode (D1) immediately breaks down and turns on, generating an overvoltage trigger signal. The first resistor (R1) limits the current to ensure controllable power consumption. At the same time, the capacitor (C1) and the second resistor (R4) in the transient suppression circuit filter out brief fluctuations during the initial power-up period to prevent false triggering. After the Schottky diode (D2) in the polarity response circuit confirms the forward current path, the state trigger signal drives the protection execution unit: the second PNP transistor Q1B turns on, forcing the first PNP transistor Q1A to turn off, cutting off the power supply to the protected circuit and preventing the 48V high voltage from invading and damaging the subsequent Hall circuit.

[0127] For example, HALL+ is short-circuited to the negative pole M- (0V) of the motor drive, resulting in a voltage difference of -5V (reverse). At this time, the Schottky diode (D2) detects the abnormal polarity and immediately reverses and cuts off. The leakage current is less than 1 microampere, and the current loop is physically blocked. The voltage regulator (D1) in the protection control circuit does not break down (because the voltage difference does not exceed the threshold), and the execution unit remains in the off state. The first PNP transistor (Q1A) and the second PNP transistor (Q1B) do not operate, ensuring that the Hall circuit is safely dormant at zero current. This design is also applicable to 42V-56V fluctuation scenarios: if the motor starts and stops, causing the drive voltage to jump to 42V, and the Hall power supply is 16V, the voltage difference of 26V still exceeds the threshold of the voltage regulator (D1). The protection circuit can respond quickly to the shutdown and monitor the current constraint through the current detection resistor (R5) to avoid thermal runaway.

[0128] In an embodiment of the present application, by real-time monitoring of the voltage changes on the low-voltage power supply end, which are generated when the high-voltage power supply end of the high-voltage working circuit is electrically coupled to the low-voltage power supply end, risk conditions such as high-voltage intrusion and reverse polarity short circuit are accurately identified; by triggering the protection execution unit to synchronously realize the triple protection of rapid power supply path cutting, physical blocking of reverse current and dynamic constraint of overload current, the risk of circuit ablation caused by response delay or function loss of traditional solutions is solved; at the same time, the space occupancy is compressed with a highly integrated architecture, and the safety of low-voltage Hall circuits in the 48V platform is guaranteed with zero standby loss, providing full-time and full-condition reliability guarantee for the vehicle electrical system.

[0129] One or more embodiments of this specification also provide an electronic device including any of the low-voltage circuit protection circuits provided in the embodiments of this application, wherein the low-voltage power supply terminal is connected to a low-voltage operating circuit, and the protected circuit is a Hall effect signal acquisition circuit. This electronic device has all the beneficial effects of the aforementioned low-voltage circuit protection circuits, and this disclosure will not elaborate further here.

[0130] like Figure 6 , which is a schematic diagram of the architecture of a vehicle provided in an embodiment of the present application. In this embodiment, the vehicle includes the aforementioned electronic device, or any low-voltage circuit protection circuit provided in the embodiments of the present application. In this embodiment, the vehicle can be a fuel-powered vehicle, a plug-in hybrid vehicle, or a new energy vehicle, etc., and this disclosure does not specifically limit this.

[0131] The vehicle has all the beneficial effects of the above-mentioned protection circuit for the low-voltage circuit, which will not be described in detail in this disclosure.

[0132] In some embodiments, a vehicle can be configured for a fully or partially autonomous driving mode. For example, while in autonomous driving mode, the vehicle can control itself and, through human interaction, determine the current state of the vehicle and its surroundings, determine the possible behavior of at least one other vehicle in the surroundings, and determine a confidence level corresponding to the likelihood that the other vehicle will perform the possible behavior, and control the vehicle based on this information. While in autonomous driving mode, the vehicle can be configured to operate without human interaction.

[0133] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0134] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0135] The embodiments, implementation methods and related technical features of the present application can be combined and replaced with each other without conflict.

[0136] The above are merely preferred embodiments of the present application and do not constitute any form of limitation to the present application. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application are still within the scope of the technical solution of the present application.

Claims

1. A protection circuit for a low voltage circuit, characterized in that: The protection circuit is connected between the low-voltage power supply end of the low-voltage working circuit and the protected circuit, and performs state switching of the protected circuit according to the voltage change of the low-voltage power supply end; wherein, the voltage change is generated when the high-voltage power supply end of the high-voltage working circuit is electrically coupled to the low-voltage power supply end.

2. The protection circuit according to claim 1, wherein: include: a voltage response unit, connected to the low-voltage power supply end, for detecting a voltage change of the low-voltage power supply end and generating a state trigger signal; The voltage change includes at least one of the following abnormal types: a voltage amplitude exceeding a preset voltage threshold, and a voltage polarity reversal.

3. The protection circuit according to claim 2, wherein: The voltage response unit includes: The protection control circuit is connected to the low-voltage power supply terminal signal, and is used to detect the voltage amplitude of the low-voltage power supply terminal and generate an overvoltage trigger signal when the voltage amplitude exceeds the preset voltage threshold.

4. The protection circuit according to claim 3, wherein: The voltage response unit includes: The polarity response circuit is connected to the low-voltage power supply terminal and is used to output a corresponding path state signal according to the power supply polarity of the power supply path of the protected circuit.

5. The protection circuit according to claim 3, wherein: The voltage response unit includes: The transient suppression circuit is connected in parallel between the low-voltage power supply terminal and the protection control circuit, and is used to suppress the transmission of power-on transient voltage and output a transient suppression signal.

6. The protection circuit according to claim 3, wherein: include: A protection execution unit is connected to the voltage response unit. When the voltage changes to a value exceeding a preset voltage threshold, the protection execution unit is configured to respond to the state trigger signal and cut off the power supply path of the protected circuit.

7. The protection circuit according to claim 4, characterized in that: include: A protection execution unit is connected to the voltage response unit. When the voltage change is a voltage polarity reversal, the protection execution unit is used to respond to the state trigger signal and perform dynamic current constraint on the protected circuit.

8. The protection circuit according to claim 3, wherein: The protection control circuit includes: the protection control circuit includes a voltage regulator and a first resistor, the cathode of the voltage regulator is connected to the low-voltage power supply end through the first resistor, and the anode is connected to the power supply end ground of the low-voltage working circuit.

9. The protection circuit according to claim 7, wherein: The polarity response circuit includes a Schottky diode, an anode of the Schottky diode is connected to the low-voltage power supply end, and a cathode of the Schottky diode is connected to the power supply control node of the protection execution unit.

10. The protection circuit according to claim 9, characterized in that: The protection execution unit includes a first PNP transistor and a second PNP transistor connected in cascade; The emitter of the first PNP transistor is connected to the cathode of the Schottky diode, and the collector is connected to the protected circuit; The base of the second PNP transistor receives the state trigger signal, and the collector is connected to the base of the first PNP transistor; The emitters of the first PNP transistor and the second PNP transistor are commonly connected to the low-voltage power supply end.

11. The protection circuit according to claim 10, wherein: The overvoltage trigger signal is input into the base of the second PNP transistor; The path state signal directly controls the emitter bias of the first PNP transistor; The protection execution unit generates the state trigger signal through the logic combination of the first PNP transistor and the second PNP transistor.

12. The protection circuit according to claim 5, wherein: The transient suppression circuit includes a capacitor and a second resistor, one end of the capacitor is grounded via the second resistor, and the other end is connected to the low-voltage power supply end.

13. The protection circuit according to claim 12, wherein: The transient suppression circuit controls the attenuation time of the transient suppression signal through an RC time constant.

14. The protection circuit according to claim 10, wherein: Also includes: A current detection resistor is connected in series between the emitter of the first PNP transistor and the low-voltage power supply terminal, and is used to monitor the output current in real time; When the voltage drop across the current detection resistor exceeds a preset voltage drop threshold, the second PNP transistor is triggered to turn on and the first PNP transistor is turned off.

15. The protection circuit according to claim 10, wherein: Also includes: The feedback resistor is connected between the base of the second PNP transistor and the emitter of the first PNP transistor.

16. The protection circuit according to claim 1, wherein: The low-voltage working circuit is a power supply circuit for the Hall sensor in the motor system.

17. The protection circuit according to claim 16, wherein: The operating voltage range of the power supply end of the low-voltage operating circuit is 5V to 16V.

18. The protection circuit according to claim 16, wherein: The high-voltage working circuit is a motor drive circuit in a motor system.

19. The protection circuit according to claim 18, wherein: The operating voltage range of the high-voltage operating circuit is 42V to 56V.

20. An electronic device, characterized in that: A protection circuit for a low voltage circuit comprising the protection circuit according to any one of claims 1 to 19.

21. A vehicle, characterized in that: The electronic device according to claim 20 or the protection circuit for the low-voltage circuit according to any one of claims 1 to 19 is included.

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