A drive circuit and a vehicle

Abstract

This application discloses a driving circuit and a vehicle for driving a light-emitting diode (LED). The driving circuit includes a driving module, a feedforward compensation module, a signal acquisition module, and a fault diagnosis module. The driving module includes a switching transistor and a first resistor, with a current sampling node configured between the switching transistor and the first resistor to provide a current sampling signal. The feedforward compensation module acquires the on-state voltage difference across the switching transistor and outputs a compensation reference voltage to the switching transistor's control terminal to compensate for the influence of temperature changes on the driving current. The signal acquisition module extracts the LED's terminal voltage signal and generates a slope signal based on the current sampling signal. The fault diagnosis module outputs the LED's fault category based on the terminal voltage signal, the current sampling signal, and the slope signal. This application implements purely hardware-based temperature feedforward compensation and fault diagnosis, improving the reliability of the LED driving circuit and vehicle safety.

Description

Technical Field

[0001] This application belongs to the field of light-emitting diode control, specifically relating to a driving circuit and a vehicle. Background Technology

[0002] Automotive LED (light-emitting diode) lights are widely used in the automotive lighting field due to their advantages such as low energy consumption, long lifespan, and fast response speed. However, automotive LED lights rely on constant current drive circuits to ensure stable brightness during operation. They also need to cope with the complex operating conditions of the automotive environment. Furthermore, the LED junction temperature is prone to increase with increasing current and ambient temperature, leading to malfunctions such as brightness decay and shortened lifespan.

[0003] Currently, most related technologies employ single-ended signal acquisition, which cannot effectively suppress common-mode interference in vehicles. They can only passively respond to temperature changes, resulting in delayed temperature compensation. Furthermore, the microcontroller-based solutions in these technologies are susceptible to electromagnetic interference and exhibit software response delays. In addition, these technologies cannot distinguish between different types of vehicle-mounted lamp malfunctions, meaning that any fault may lead to unnecessary control of the lamps, thereby affecting lighting and driving safety. Summary of the Invention

[0004] The purpose of this application is to provide a drive circuit and a vehicle, which is achieved as follows: In a first aspect, embodiments of this application provide a driving circuit for driving a light-emitting diode, the circuit comprising: a driving module, a feedforward compensation module, a signal acquisition module, and a fault detection module; The driving module is connected in series with the light-emitting diode. The driving module includes a switching transistor and a first resistor. The switching transistor is used to provide driving current to the light-emitting diode. A current sampling node is configured between the switching transistor and the first resistor. The current sampling node is used to provide a current sampling signal that reflects the driving current. The input terminal of the feedforward compensation module is connected to the switching transistor to collect the on-state voltage difference across the switching transistor. The output terminal of the feedforward compensation module is connected to the control terminal of the switching transistor to output a compensation reference voltage based on the on-state voltage difference to compensate for the effect of temperature change on the driving current. The input terminal of the signal acquisition module is connected to both ends of the light-emitting diode and the current sampling node, respectively, for extracting the terminal voltage signal of the light-emitting diode and generating the slope signal of the driving current based on the current sampling signal; The input terminal of the fault discrimination module is connected to the output terminal of the signal acquisition module, and is used to output the fault category of the light-emitting diode based on the terminal voltage signal, the current sampling signal and the slope signal.

[0005] Optionally, the driving module further includes a first operational amplifier; The non-inverting input of the first operational amplifier is used to receive the compensation reference voltage, the inverting input of the first operational amplifier is connected to the current sampling node to acquire the current sampling signal, and the output of the first operational amplifier is connected to the control terminal of the switching transistor. The first operational amplifier is used to control the switching transistor according to the compensation reference voltage and the current sampling signal, so that the switching transistor outputs the drive current.

[0006] Optionally, the feedforward compensation module includes a differential amplifier circuit, a filter circuit, and an addition circuit; The input terminal of the differential amplifier circuit is connected to the drain and source of the switching transistor to acquire the conduction voltage difference, differentially amplify the conduction voltage difference, and output the amplified conduction voltage difference as the temperature sampling voltage. The input terminal of the filtering circuit is connected to the output terminal of the differential amplifier circuit to obtain the temperature sampling voltage, filter the temperature sampling voltage, and output the filtered temperature sampling voltage. The first input terminal of the adder circuit is used to receive a preset reference voltage. The second input terminal of the adder circuit is connected to the output terminal of the filter circuit to obtain the filtered temperature sampling voltage. The third input terminal of the adder circuit is used to receive a preset bias voltage. The output terminal of the adder circuit is connected to the control terminal of the switch. The addition circuit is used to subtract the reference voltage from the bias voltage, and then subtract the filtered temperature sampling voltage to obtain the compensation reference voltage, and output the compensation reference voltage to the control terminal of the switching transistor.

[0007] Optionally, the differential amplifier circuit includes a second operational amplifier, a second resistor, a third resistor, a fourth resistor, and a fifth resistor; The non-inverting input terminal of the second operational amplifier is connected to the drain of the switching transistor via the second resistor, and is also connected to the output terminal of the second operational amplifier via the fourth resistor. The inverting input terminal of the second operational amplifier is connected to the source of the switching transistor via the third resistor and grounded via the fifth resistor; The second operational amplifier is used to differentially amplify the conduction voltage difference, use the amplified conduction voltage difference as the temperature sampling voltage, and output the temperature sampling voltage at the output terminal of the second operational amplifier.

[0008] Optionally, the filter circuit includes a sixth resistor and a first capacitor; The sixth resistor is connected in series between the output terminal of the differential amplifier circuit and the second input terminal of the adder circuit; One end of the first capacitor is connected to the node between the sixth resistor and the second input terminal of the addition circuit, and the other end is grounded; The filtering circuit is used to filter the temperature sampling voltage through the sixth resistor and the first capacitor, and output the filtered temperature sampling voltage.

[0009] Optionally, the addition circuit includes a third operational amplifier, a seventh resistor, an eighth resistor, a ninth resistor, and a tenth resistor; The inverting input terminal of the third operational amplifier receives the reference voltage via the seventh resistor, and receives the filtered temperature sampling voltage via the eighth resistor. It is also connected to the output terminal of the third operational amplifier via the ninth resistor. The non-inverting input of the third operational amplifier receives the bias voltage via the tenth resistor; The third operational amplifier is used to subtract the reference voltage from the bias voltage, and then subtract the filtered temperature sampling voltage to obtain the compensation reference voltage, and output the compensation reference voltage at the output terminal of the third operational amplifier.

[0010] Optionally, the signal acquisition module includes a voltage detection circuit and a slope detection circuit; The first input terminal of the voltage detection circuit is connected to the anode of the light-emitting diode, and the second input terminal of the voltage detection circuit is connected to the cathode of the light-emitting diode. The voltage detection circuit is used to acquire the voltage across the light-emitting diode, perform differential sampling on the voltage across the light-emitting diode, and output the terminal voltage signal. The input terminal of the slope detection circuit is connected to the current sampling node. The slope detection circuit is used to acquire the current sampling signal, perform differentiation processing on the current sampling signal, and output the slope signal.

[0011] Optionally, the voltage detection circuit includes a fourth operational amplifier, an eleventh resistor, a twelfth resistor, a thirteenth resistor, and a fourteenth resistor; The non-inverting input terminal of the fourth operational amplifier is connected to the anode of the light-emitting diode via the eleventh resistor, and is connected to the output terminal of the fourth operational amplifier via the thirteenth resistor; The inverting input terminal of the fourth operational amplifier is connected to the cathode of the light-emitting diode via the twelfth resistor, and grounded via the fourteenth resistor; The fourth operational amplifier is used to differentially sample the voltage across the light-emitting diode to obtain the terminal voltage signal, and output the terminal voltage signal at the output terminal of the fourth operational amplifier.

[0012] Optionally, the slope detection circuit includes a fifth operational amplifier, an input capacitor, a fifteenth resistor, and a sixteenth resistor; The inverting input terminal of the fifth operational amplifier is connected to the current sampling node via the input capacitor, and is connected to the output terminal of the fifth operational amplifier via the fifteenth resistor; The non-inverting input terminal of the fifth operational amplifier is grounded via the sixteenth resistor; The fifth operational amplifier is used to differentiate the current sampling signal to obtain the slope signal, and outputs the slope signal at the output terminal of the fifth operational amplifier.

[0013] Optionally, the fault detection module includes a first comparator, a second comparator, a third comparator, an OR gate, an inverter, an AND gate, and an encoding output circuit; The non-inverting input of the first comparator is connected to the current sampling node to acquire the current sampling signal. The inverting input of the first comparator is used to receive a preset overcurrent threshold voltage. The first comparator is used to output an overcurrent fault signal based on the comparison result between the current sampling signal and the overcurrent threshold voltage. The non-inverting input of the second comparator is connected to the output of the slope detection circuit to acquire the slope signal. The inverting input of the second comparator is used to receive a preset slope threshold voltage. The second comparator is used to output a slope fault signal based on the comparison result between the slope signal and the slope threshold voltage. The non-inverting input of the third comparator is used to receive a preset undervoltage threshold voltage. The inverting input of the third comparator is connected to the output of the voltage detection circuit to acquire the terminal voltage signal. The third comparator is used to output a load fault signal based on the comparison result between the undervoltage threshold voltage and the terminal voltage signal. The first input terminal of the OR gate is connected to the output terminal of the first comparator to obtain the overcurrent fault signal, and the second input terminal of the OR gate is connected to the output terminal of the second comparator to obtain the slope fault signal. The OR gate is used to output a severe fault signal based on the overcurrent fault signal and the slope fault signal. The input terminal of the inverter is connected to the output terminal of the second comparator to acquire the slope fault signal. The inverter is used to invert the slope fault signal and output the inverted slope fault signal. The first input terminal of the AND gate is connected to the output terminal of the first comparator to obtain the overcurrent fault signal. The second input terminal of the AND gate is connected to the output terminal of the inverter to obtain the inverted slope fault signal. The AND gate is used to output a mild overload signal based on the overcurrent fault signal and the inverted slope fault signal. The input terminal of the encoding output circuit is connected to the output terminal of the third comparator, the output terminal of the OR gate, and the output terminal of the AND gate, respectively, for acquiring the load fault signal, the severe fault signal, and the mild overload signal, and outputting the fault category of the light-emitting diode according to the load fault signal, the severe fault signal, and the mild overload signal.

[0014] Optionally, the step of outputting the fault category of the light-emitting diode based on the load fault signal, the severe fault signal, and the mild overload signal includes: If the severe fault signal is low, the mild overload signal is low, and the load fault signal is low, then the encoding output circuit outputs that the light-emitting diode is in normal working condition. If the severe fault signal is high, the mild overload signal is low, and the load fault signal is high, then the encoding output circuit outputs that the light-emitting diode is short-circuit fault. If the severe fault signal is low, the mild overload signal is low, and the load fault signal is high, then the encoding output circuit outputs that the light-emitting diode is open-circuit fault. If the slight overload signal is high, the encoding output circuit outputs that the light-emitting diode is in a slight overload fault. If the severe fault signal is high, the mild overload signal is low, and the load fault signal is low, then the encoding output circuit outputs that the light-emitting diode indicates an impulse overcurrent fault.

[0015] Secondly, embodiments of this application provide a vehicle that includes the drive circuit described above.

[0016] The embodiments of this application have the following advantages: In this embodiment, the driving circuit drives a light-emitting diode (LED). The driving circuit includes a driving module, a feedforward compensation module, a signal acquisition module, and a fault diagnosis module. The driving module is connected in series with the LED. The driving module includes a switching transistor and a first resistor. The switching transistor provides a driving current to the LED. A current sampling node is configured between the switching transistor and the first resistor to provide a current sampling signal reflecting the driving current. This application provides the driving current through the switching transistor and configures a current sampling node between the switching transistor and the first resistor, enabling direct acquisition of the current sampling signal reflecting the driving current. This provides accurate current feedback for subsequent temperature compensation and fault diagnosis, eliminating the need for an additional independent current sensor.

[0017] The input of the feedforward compensation module is connected to the switching transistor to collect the on-state voltage difference across the transistor. The output of the feedforward compensation module is connected to the control terminal of the switching transistor to output a compensation reference voltage based on the on-state voltage difference, thereby compensating for the effect of temperature changes on the drive current. This application indirectly obtains temperature change information by collecting the on-state voltage difference across the switching transistor and outputs a compensation reference voltage to the control terminal of the switching transistor accordingly, realizing temperature feedforward compensation. This allows for proactive adjustment of the drive current before temperature changes, improving the stability of the LED's brightness across the entire temperature range.

[0018] The input terminals of the signal acquisition module are connected to both ends of the LED and the current sampling node, respectively, to extract the terminal voltage signal of the LED and generate the slope signal of the driving current based on the current sampling signal. This application can comprehensively obtain the working status information of the LED by simultaneously acquiring the terminal voltage signal of the LED and the current sampling signal of the current sampling node and generating a slope signal reflecting the rate of change of current. This provides multi-dimensional and high-precision signal basis for subsequent fault diagnosis, which is conducive to accurately identifying different types of faults such as short circuit, open circuit, and loose connection of wiring harness.

[0019] The input of the fault diagnosis module is connected to the output of the signal acquisition module. It outputs the fault category of the LED based on the terminal voltage signal, current sampling signal, and slope signal. By comprehensively analyzing these three signals, different fault types of LEDs can be distinguished. This facilitates tiered protection measures based on fault categories, avoiding the problem in existing solutions where any fault could lead to unnecessary control of the lighting fixtures, thus affecting lighting and driving safety. This ensures the continuity and safety of vehicle lighting. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0021] Figure 1 This is a logic diagram of a driving circuit provided in one embodiment of this application; Figure 2 This is a circuit diagram of a driving module and a feedforward compensation module provided in an embodiment of this application; Figure 3 This is a circuit diagram of a voltage detection circuit and a slope detection circuit provided in an embodiment of this application; Figure 4 This is a circuit diagram of a fault detection module provided in one embodiment of this application. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the various embodiments of this application will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been presented in the various embodiments of this application to enable readers to better understand this application. However, the technical solutions claimed in this application can be implemented even without these technical details and various changes and updates based on the following embodiments. The division of the various embodiments below is for the convenience of description and should not constitute any limitation on the specific implementation of this application. The various embodiments can be combined with and referenced by each other without contradiction.

[0023] Automotive LED lights are widely used in the automotive lighting field due to their advantages such as low energy consumption, long lifespan, and fast response speed, including headlights, taillights, and daytime running lights. However, automotive LED lights rely on constant current drive circuits to ensure stable brightness during operation. They also need to cope with the complex operating conditions of the automotive environment, such as a wide temperature range of -40℃ to 85℃, strong electromagnetic interference, and frequent vibrations. Furthermore, the LED junction temperature tends to rise with increasing current and ambient temperature, leading to brightness decay and shortened lifespan.

[0024] Currently, the technical level of automotive LED constant current drive circuits exhibits a clear stratification. Among related technologies, some solutions rely on microcontrollers for temperature compensation and fault diagnosis. While these solutions can achieve basic functions, microcontrollers are prone to malfunctions due to electromagnetic interference in the automotive environment, and they also increase circuit complexity, cost, and power consumption, making them unsuitable for the harsh environment of wide-temperature and high-vibration automotive applications. Mid-to-low-end automotive LEDs, such as taillights and daytime running lights, employ pure hardware drive solutions with simple detection and compensation methods, lacking temperature feedforward compensation mechanisms and graded fault diagnosis, failing to meet the requirements for high precision and high reliability. While mid-to-high-end solutions have improved, they have not yet formed a mature architecture that fully integrates temperature feedforward compensation and graded fault diagnosis throughout the entire process, making it difficult to balance accuracy, reliability, and simplicity.

[0025] The following problems exist in the existing technology: Low temperature compensation accuracy and lack of a feedforward mechanism prevent LEDs from achieving adaptive and stable brightness across the entire temperature range. When the ambient temperature in the vehicle changes, the brightness of the LEDs fluctuates significantly, becoming dimmer at low temperatures and overloaded at high temperatures. Long-term use can lead to excessively high junction temperatures, accelerating aging and shortening lifespan, and even a sudden drop in brightness, affecting driving illumination. This problem stems from the fact that existing pure hardware solutions mostly use single-ended signal acquisition to obtain power device temperature information, lacking differential anti-interference design. This fails to effectively suppress common-mode interference in the vehicle environment, and the absence of a temperature feedforward compensation architecture results in a passive response to temperature changes, causing compensation lag. While microcontroller-based solutions can optimize compensation accuracy, microcontrollers are susceptible to electromagnetic interference in the vehicle environment and wide-temperature environments, leading to malfunctions. Furthermore, they increase circuit complexity, indirectly affecting compensation stability.

[0026] Current slope detection suffers from poor reliability, prone to false detections and missed detections, making it difficult to accurately identify transient faults. When an LED malfunctions, the current undergoes a sudden, instantaneous change. Existing solutions cannot quickly capture this change, either failing to detect the fault and allowing it to escalate, or misinterpreting normal current fluctuations as a fault and triggering unnecessary protection actions, causing the LED lamp to reduce current and thus affecting illumination. This problem arises because existing pure hardware solutions lack an active amplification structure, have weak resistance to high-frequency electromagnetic interference, cannot amplify weak current slope changes, and lack targeted anti-interference devices, leading to signal distortion. Microcontroller-based solutions require software processing of the slope signal, but software computation has response delays, failing to meet the rapid identification requirements of transient vehicle faults, and the software logic is susceptible to interference and misprocessing.

[0027] The lack of a tiered fault diagnosis mechanism and the simplistic fault handling methods negatively impact the continuity of vehicle lighting and driving safety. Regardless of the fault type or severity, even a minor overload that doesn't damage components may trigger unnecessary control over the lights, affecting illumination. Furthermore, the inability to differentiate fault types significantly complicates subsequent maintenance and troubleshooting. This problem stems from the fact that existing pure hardware solutions rely on a single comparator for fault detection, lacking a tiered judgment architecture with multiple thresholds and logic combinations. This makes it impossible to distinguish fault types and levels, potentially leading to unnecessary control over the lights regardless of the fault. Microcontroller-based tiered solutions suffer from complex software logic, consuming significant microcontroller resources and being susceptible to interference leading to misjudgments. This also increases the risk of system failure and fails to meet the high reliability requirements of automotive applications.

[0028] Therefore, this application provides a drive circuit and vehicle that adopts a pure hardware proportional operation architecture, requiring no microcontroller involvement in any calculations. All functions are implemented through the circuit connections and logic combinations of hardware devices. The drive module provides a stable operating current to the vehicle's LEDs. The feedforward compensation module, through precise temperature signal acquisition and reference correction, predicts temperature changes in advance and dynamically corrects the constant current reference voltage to achieve temperature feedforward compensation. The signal acquisition module uses a pure hardware active amplification detection method to extract the instantaneous current change trend, i.e., the slope, providing accurate basis for fault diagnosis. The fault diagnosis module identifies the fault type and level through comparator comparison and logic combination, outputting graded protection signals. It also converts the fault signals into digital codes and reports them. The overall architecture is simple, responsive, and adaptable to the complex automotive environment. The implementation steps of each module are highly consistent with the circuit structure and core methods, executing in the logical order of constant current drive, temperature feedforward compensation, current slope detection, graded fault diagnosis, and fault type output.

[0029] Reference Figure 1 The diagram shows a logic schematic of a driving circuit provided in one embodiment of this application.

[0030] In this embodiment, the driving circuit is used to drive light-emitting diodes (LEDs). The driving circuit includes a driving module, a feedforward compensation module, a signal acquisition module, and a fault diagnosis module. In specific implementations, the driving circuit provided in this application is suitable for automotive LED loads such as headlights, daytime running lights, taillights, and matrix headlights.

[0031] The driving module can refer to a circuit module used to provide a constant driving current for the light-emitting diode.

[0032] A feedforward compensation module can refer to a circuit module used to acquire temperature-related signals in advance and compensate for the drive current.

[0033] A signal acquisition module can refer to a circuit module used to extract the operating status signal of a light-emitting diode.

[0034] A fault diagnosis module can refer to a circuit module used to determine the fault type of a light-emitting diode based on the collected signals.

[0035] In this embodiment, the driving module can be connected in series with the light-emitting diode. The driving module may include a switching transistor and a first resistor. The switching transistor is used to provide driving current to the light-emitting diode. A current sampling node is configured between the switching transistor and the first resistor. The current sampling node is used to provide a current sampling signal that reflects the driving current.

[0036] Among them, a switching transistor can refer to a controlled semiconductor switching device that adjusts the conduction level by changing the voltage or current at its control terminal, thereby controlling the magnitude of the driving current flowing through the light-emitting diode.

[0037] The first resistor can refer to the resistor connected in series between the source of the switching transistor and ground, which is used to convert the drive current into a voltage signal.

[0038] The current sampling node can refer to the circuit connection point between the switching transistor and the first resistor, from which a voltage signal reflecting the magnitude of the drive current can be obtained.

[0039] The current sampling signal can refer to the voltage signal derived from the current sampling node. Its magnitude is proportional to the driving current and it is used for feedback control and fault detection.

[0040] In a practical implementation, the input terminal of the drive circuit can be connected to the vehicle power supply, which powers the entire drive circuit. A protection module is connected in series at the output terminal of the vehicle power supply, and this protection module is connected between the vehicle power supply and the LED.

[0041] The protection module suppresses inrush currents generated at power-on and filters the input voltage of the vehicle power supply. During startup or voltage fluctuations, the vehicle power supply may generate momentary high voltage or high-frequency noise. Direct connection to the drive circuit and LEDs could lead to overcurrent damage to the LEDs or breakdown of power devices. The protection module clamps the input voltage within a safe range and filters out high-frequency interference, providing a stable operating voltage for the subsequent drive module and LEDs.

[0042] The protection module can be implemented by one or more combinations of transient voltage suppression diodes, varistors, LC filter networks or π-type filter circuits. The specific circuit structure is selected according to the characteristics of the vehicle power supply and the protection level requirements, and this application does not make specific limitations in this regard.

[0043] The voltage processed by the protection module is supplied to the anode of the LED, and the cathode of the LED is connected to the switching transistor in the driver module, and the driver circuit enters normal operation.

[0044] In this embodiment, the input terminal of the feedforward compensation module is connected to the switching transistor to collect the on-state voltage difference across the switching transistor. The output terminal of the feedforward compensation module is connected to the control terminal of the switching transistor to output a compensation reference voltage based on the on-state voltage difference to compensate for the effect of temperature changes on the drive current.

[0045] Among them, the conduction voltage difference refers to the voltage drop between the drain and source of the switching transistor when it is in the conduction state. Its magnitude increases with the increase of temperature and can indirectly reflect the temperature change of the switching transistor and the surrounding circuit.

[0046] The compensation reference voltage can refer to the dynamic voltage signal output by the feedforward compensation module after processing the conduction voltage difference, which is used to adjust the current reference of the drive module to achieve temperature compensation.

[0047] In this embodiment, the input terminal of the signal acquisition module is connected to both ends of the light-emitting diode and the current sampling node, respectively, to extract the terminal voltage signal of the light-emitting diode and generate the slope signal of the driving current based on the current sampling signal.

[0048] Among them, the terminal voltage signal refers to the voltage difference between the anode and cathode of the light-emitting diode. It is relatively stable when working normally, but drops sharply when an open circuit or short circuit occurs, which is an important basis for judging load faults.

[0049] The slope signal can refer to the voltage signal obtained after differentiating the current sampling signal. It reflects the rate of change of the driving current and is used to detect sudden changes in current caused by short circuits or loose connections in the wiring harness.

[0050] In this embodiment of the application, the input terminal of the fault discrimination module is connected to the output terminal of the signal acquisition module, and is used to output the fault category of the light-emitting diode based on the terminal voltage signal, the current sampling signal and the slope signal.

[0051] Among them, the fault category can refer to the result output by the fault discrimination module after classifying and judging the working state of the light-emitting diode, including normal working state and various fault types such as short circuit, open circuit, light overload, and impulse overcurrent.

[0052] This application provides drive current through a switching transistor and configures a current sampling node between the switching transistor and the first resistor. This allows for direct acquisition of the current sampling signal reflecting the drive current, providing accurate current feedback for subsequent temperature compensation and fault diagnosis, eliminating the need for an additional independent current sensor. This application indirectly obtains temperature change information by acquiring the on-state voltage difference across the switching transistor and outputs a compensation reference voltage to the control terminal of the switching transistor accordingly. This achieves temperature feedforward compensation, actively adjusting the drive current before temperature changes and improving the stability of the LED's brightness across the entire temperature range. This application simultaneously acquires the terminal voltage signal across the LED and the current sampling signal from the current sampling node, generating a slope signal reflecting the rate of current change. This comprehensively acquires the LED's operating status information, providing multi-dimensional and high-precision signal basis for subsequent fault diagnosis, facilitating accurate identification of different types of faults such as short circuits, open circuits, and loose wiring connections. By combining three signals—terminal voltage signal, current sampling signal, and slope signal—fault identification can distinguish different fault types of LEDs, facilitating the implementation of graded protection measures based on fault categories. This avoids the problem in existing solutions where any fault might lead to unnecessary control of the lighting fixtures, thereby affecting lighting and driving safety, and ensures the continuity and safety of driving lighting.

[0053] Reference Figure 2 The diagram shows a circuit diagram of a driving module and a feedforward compensation module provided in an embodiment of this application.

[0054] The driving module may include a switching transistor Q1 and a first resistor R1. The driving module can refer to a circuit module used to provide a constant driving current to the light-emitting diode D1.

[0055] Optionally, the driver module also includes a first operational amplifier U1.

[0056] The first operational amplifier U1 can refer to the operational amplifier in the driver module used to implement closed-loop constant current control, which adjusts the conduction level of the switching transistor by comparing the compensation reference voltage and the current sampling signal. The non-inverting input of the operational amplifier is... Figure 2 The "+" symbol indicates that the inverting input is located at... Figure 2 The Chinese character "-" is used to represent this.

[0057] In this embodiment, the non-inverting input of the first operational amplifier U1 is used to receive the compensation reference voltage, the inverting input of the first operational amplifier U1 is connected to the current sampling node to acquire the current sampling signal, and the output of the first operational amplifier is connected to the control terminal of the switching transistor Q1.

[0058] In this embodiment, the first operational amplifier U1 is used to control the switch Q1 according to the compensation reference voltage and current sampling signal, so that the switch Q1 outputs a drive current.

[0059] The first operational amplifier U1 has two input terminals, one output terminal, one power supply terminal, and one ground terminal. The non-inverting input terminal receives the compensation reference voltage from the feedforward compensation module, serving as the reference target value for constant current control. The inverting input terminal is connected to the current sampling node to acquire a current sampling signal reflecting the magnitude of the current drive current, serving as the actual feedback value. The output terminal is directly connected to the control terminal of the switching transistor Q1, controlling the conduction level of Q1 based on the difference between the two input signals. The power supply terminal is connected to the positive terminal of the auxiliary power supply, providing the operating voltage for the first operational amplifier U1. The ground terminal is connected to the system ground, forming a complete current loop.

[0060] In the specific implementation, Figure 2 The circuit composition of the driver module is shown. The LED D1 serves as the load. The driver module consists of a first operational amplifier U1, a switching transistor Q1, and a first resistor R1. The first resistor R1 is a sampling resistor, and its value can be set to 1Ω. The switching transistor Q1 can be an NMOS transistor.

[0061] Taking a drive current of 1A as an example, at an ambient temperature of 25℃, the drain-source on-state voltage difference of switch Q1 is 0.02V, while at an ambient temperature of 125℃, the drain-source on-state voltage difference of switch Q1 increases to 0.04V. The on-state voltage difference of switch Q1 increases with increasing temperature, and this characteristic is used by the feedforward compensation module to indirectly obtain temperature change information.

[0062] This application provides a constant drive current to the LED through a driver module. The first operational amplifier in the driver module performs closed-loop negative feedback control on the switching transistor based on the compensation reference voltage and current sampling signal, stabilizing the drive current at the target value. Simultaneously, utilizing the characteristic that the switching transistor's on-state voltage difference increases with temperature, it provides indirect temperature information to the feedforward compensation module, eliminating the need for an additional temperature sensor. This solves the problems of low temperature detection accuracy and susceptibility of constant current control to temperature variations in existing solutions, achieving a simple circuit structure and a fast-responding constant current drive effect.

[0063] Optionally, the feedforward compensation module includes a differential amplifier circuit, a filter circuit, and an adder circuit.

[0064] The feedforward compensation module can be composed of three cascaded sub-circuits: a differential amplifier circuit, a filter circuit, and an adder circuit. The differential amplifier circuit is responsible for acquiring and amplifying the forward voltage difference across the switching transistor, the filter circuit smooths the amplified signal, and the adder circuit performs calculations with the processed signal and a reference voltage to ultimately generate a dynamic reference voltage for temperature compensation.

[0065] Among them, a differential amplifier circuit can refer to an amplifier circuit that can amplify the voltage difference between two input terminals while suppressing common-mode interference signals on the two input terminals.

[0066] A filter circuit can refer to a circuit used to filter out high-frequency noise in a signal and retain the effective low-frequency components. In this application, an RC low-pass filter structure can be used.

[0067] An addition circuit can refer to an analog arithmetic circuit capable of performing addition and subtraction operations on multiple input voltage signals.

[0068] In this embodiment of the application, the input terminal of the differential amplifier circuit is connected to the drain and source of the switching transistor to collect the conduction voltage difference, and differentially amplify the conduction voltage difference, and output the amplified conduction voltage difference as the temperature sampling voltage.

[0069] The two input terminals of the differential amplifier circuit are connected to the drain and source of the switching transistor, respectively, to acquire the voltage difference across the transistor in real time when it is turned on. The differential amplifier circuit amplifies this on-state voltage difference proportionally. Since the on-state voltage difference increases with temperature, the amplified voltage signal can linearly reflect temperature changes. This signal is the temperature sampling voltage and is output to the filter circuit.

[0070] Temperature sampling voltage refers to the voltage signal obtained after the differential amplifier circuit amplifies the conduction voltage difference of the switching transistor. Its magnitude is linearly related to the junction temperature of the switching transistor and is used to indirectly characterize temperature changes.

[0071] In this embodiment of the application, the input terminal of the filter circuit is connected to the output terminal of the differential amplifier circuit to obtain the temperature sampling voltage, filter the temperature sampling voltage, and output the filtered temperature sampling voltage.

[0072] The filter circuit receives the temperature sampling voltage output from the differential amplifier circuit, performs low-pass filtering on the voltage signal to filter out high-frequency interference and noise components coupled to the signal line in the vehicle environment, and outputs a smooth and stable filtered temperature sampling voltage for use by the subsequent addition circuit.

[0073] The filtered temperature sampling voltage can refer to the smoothed voltage signal obtained after the temperature sampling voltage has passed through a filtering circuit to remove high-frequency noise.

[0074] In this embodiment, the first input terminal of the adder circuit is used to receive a preset reference voltage, the second input terminal of the adder circuit is connected to the output terminal of the filter circuit to obtain the filtered temperature sampling voltage, the third input terminal of the adder circuit is used to receive a preset bias voltage, and the output terminal of the adder circuit is connected to the control terminal of the switch.

[0075] The adder circuit has three inputs and one output. The first input is connected to a preset reference voltage, which is a fixed value. The second input is connected to a filtered temperature sampling voltage, which varies with temperature. The third input is connected to a preset bias voltage, which provides DC operating bias for the adder circuit. The output of the adder circuit is connected to the control terminal of the switching transistor, and outputs a temperature-compensated dynamic reference voltage.

[0076] The reference voltage can refer to a preset fixed reference voltage, which serves as the initial reference value for constant current drive and does not change with temperature.

[0077] The bias voltage can refer to the preset DC bias voltage, which provides a suitable DC operating point for the adder circuit and ensures that the operational amplifier operates in the linear region.

[0078] In this embodiment, the addition circuit is used to subtract the reference voltage from the bias voltage, and then subtract the filtered temperature sampling voltage to obtain the compensation reference voltage, and output the compensation reference voltage to the control terminal of the switching transistor.

[0079] The addition circuit performs subtraction on the three input voltages. The operation involves subtracting the reference voltage from the bias voltage, and then subtracting the filtered temperature sampling voltage. The result is the compensation reference voltage. As the temperature rises, the filtered temperature sampling voltage increases, and the compensation reference voltage decreases accordingly. This reduces the drive current, suppressing further temperature increases and achieving temperature feedforward compensation. The compensation reference voltage is output to the control terminal of the switching transistor, serving as a dynamic reference for the drive module to adjust the drive current.

[0080] This application uses a differential amplifier circuit to acquire the forward voltage difference across the switching transistor and amplifies it differentially to obtain the temperature sampling voltage. After filtering out high-frequency noise, an adder circuit subtracts the reference voltage and the filtered temperature sampling voltage from the bias voltage to generate a compensation reference voltage, which is then output to the switching transistor control terminal. When the temperature rises, the compensation reference voltage automatically decreases, reducing the drive current in advance, thus achieving pure hardware temperature feedforward compensation. This solves the problems of low temperature detection accuracy and compensation lag in existing solutions, achieving stable brightness and rapid response of the LED across the entire temperature range.

[0081] Optionally, refer to Figure 2 The differential amplifier circuit includes a second operational amplifier U2, a second resistor R2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5.

[0082] The specific circuit structure of the differential amplifier circuit is as follows: Figure 2 As shown, it consists of a second operational amplifier U2 and four resistors. The four resistors are the second resistor R2, the third resistor R3, the fourth resistor R4, and the fifth resistor R5, which form a differential proportional amplifier structure around the second operational amplifier U2.

[0083] The second operational amplifier U2 can refer to the core active device in a differential amplifier circuit, which is used to proportionally amplify the voltage difference between the two input terminals.

[0084] The second resistor R2 can refer to the resistor connected between the drain of the switching transistor Q1 and the non-inverting input terminal of the second operational amplifier U2.

[0085] The third resistor R3 can refer to the resistor connected between the source of the switching transistor Q1 and the inverting input of the second operational amplifier U2.

[0086] The fourth resistor R4 can refer to the feedback resistor connected between the non-inverting input and output of the second operational amplifier U2.

[0087] The fifth resistor R5 can refer to the resistor connected between the inverting input terminal of the second operational amplifier U2 and ground.

[0088] The non-inverting input of the second operational amplifier U2 is connected to the drain of the switching transistor Q1 via the second resistor R2, and is connected to the output of the second operational amplifier U2 via the fourth resistor R4.

[0089] In this embodiment, the non-inverting input of the second operational amplifier U2 is connected to the drain of the switching transistor Q1 via a second resistor R2 to receive the drain voltage. Simultaneously, this non-inverting input is also connected to the output of the second operational amplifier U2 via a fourth resistor R4, forming a positive feedback path. The second resistor R2 and the fourth resistor R4 together determine the signal gain of the non-inverting input.

[0090] The inverting input of the second operational amplifier U2 is connected to the source of the switching transistor Q1 via the third resistor R3, and grounded via the fifth resistor R5.

[0091] In this embodiment, the inverting input of the second operational amplifier U2 is connected to the source of the switching transistor Q1 via a third resistor R3 to receive the source voltage. Simultaneously, this inverting input is also connected to ground via a fifth resistor R5, forming a reference potential for the inverting input. The third resistor R3 and the fifth resistor R5 together determine the signal gain of the inverting input.

[0092] The second operational amplifier U2 is used to differentially amplify the conduction voltage difference, and uses the amplified conduction voltage difference as the temperature sampling voltage, and outputs the temperature sampling voltage at the output terminal of the second operational amplifier U2.

[0093] In this embodiment, the second operational amplifier U2 receives the voltage across the drain and source terminals of the switching transistor Q1 and proportionally amplifies the voltage difference between the two input terminals. When the resistances of the second resistor R2 and the third resistor R3 are equal, and the resistances of the fourth resistor R4 and the fifth resistor R5 are equal, the amplification factor of the differential amplifier circuit is the ratio of the resistance of the fourth resistor R4 to the resistance of the second resistor R2. The amplified forward voltage difference is the temperature sampling voltage, which is output from the output terminal of the second operational amplifier U2 to the filter circuit.

[0094] In practical implementation, in the differential amplifier circuit, the resistance values ​​of the second resistor R2 and the third resistor R3 can be 1KΩ, and the resistance values ​​of the fourth resistor R4 and the fifth resistor R5 can be 10KΩ. The amplification factor of the differential amplifier circuit is the ratio of the fourth resistor R4 to the second resistor R2, which is 10 times. At an ambient temperature of 25℃, the forward voltage difference of the switching transistor Q1 is 0.02V. After 10 times differential amplification, the temperature sampling voltage is 0.2V. At an ambient temperature of 125℃, the forward voltage difference of the switching transistor Q1 is 0.04V. After 10 times differential amplification, the temperature sampling voltage is 0.4V. The temperature sampling voltage increases with increasing temperature, providing a temperature-linearly related compensation basis for the subsequent addition circuit.

[0095] This application constructs a differential proportional amplifier circuit using a second operational amplifier U2 and two resistors R2, R3, R4, and R5. This circuit acquires and proportionally amplifies the forward voltage difference across the drain and source of the switching transistor Q1, outputting the amplified forward voltage difference as the temperature sampling voltage. Since the forward voltage difference increases linearly with temperature, the temperature sampling voltage accurately reflects temperature changes, and the differential amplification structure effectively suppresses common-mode interference in the vehicle environment. This solves the problems of poor anti-interference capability and low temperature detection accuracy in existing single-ended signal acquisition solutions, achieving high-precision, anti-interference temperature signal acquisition.

[0096] Optionally, refer to Figure 2 The filter circuit includes a sixth resistor R6 and a first capacitor C1.

[0097] The specific circuit structure of the filter circuit is as follows: Figure 2 As shown, it consists of a resistor and a capacitor, namely the sixth resistor R6 and the first capacitor C1, which together form a first-order RC low-pass filter network.

[0098] The sixth resistor R6 can refer to the resistor connected in series between the output of the differential amplifier circuit and the input of the adder circuit. It is used to limit the signal transmission rate and, together with the first capacitor C1, forms a filtering time constant.

[0099] The first capacitor C1 can refer to a capacitor with one end connected to the rear node of the sixth resistor R6 and the other end grounded, used to ground high-frequency noise.

[0100] The sixth resistor R6 is connected in series between the output terminal of the differential amplifier circuit and the second input terminal of the adder circuit.

[0101] In the filter circuit, the resistance of the sixth resistor R6 can be 1KΩ, and the capacitance of the first capacitor C1 can be 100nF.

[0102] In this embodiment, one end of the sixth resistor R6 is connected to the output of the second operational amplifier U2 in the differential amplifier circuit, and the other end is connected to the inverting input of the third operational amplifier U3 in the adder circuit. After the temperature sampling voltage is output from the differential amplifier circuit, it is transmitted to the adder circuit through the sixth resistor R6. The sixth resistor R6 plays a role in current limiting and delay in the signal path.

[0103] One end of the first capacitor C1 is connected to the node between the sixth resistor R6 and the second input terminal of the addition circuit, and the other end is grounded.

[0104] In this embodiment, one end of the first capacitor C1 is connected to the connection node between the sixth resistor R6 and the inverting input terminal of the third operational amplifier U3, and the other end of the first capacitor C1 is grounded. The sixth resistor R6 and the first capacitor C1 form an RC filter network at this node to perform low-pass filtering on the transmitted temperature sampling voltage and ground high-frequency noise.

[0105] The filtering circuit is used to filter the temperature sampling voltage through the sixth resistor R6 and the first capacitor C1, and output the filtered temperature sampling voltage.

[0106] In this embodiment, the filter circuit uses an RC low-pass network formed by the sixth resistor R6 and the first capacitor C1 to bypass the high-frequency interference components in the temperature sampling voltage to ground, while retaining the low-frequency effective signal that reflects temperature changes, thereby outputting a smooth and stable filtered temperature sampling voltage to the addition circuit.

[0107] The sixth resistor R6 and the first capacitor C1 together determine the time constant and cutoff frequency of the filter circuit, effectively filtering out high-frequency noise in the temperature sampling voltage, ensuring that the filtered temperature sampling voltage output to the addition circuit is smooth and stable, and avoiding high-frequency interference from affecting the compensation accuracy.

[0108] Optionally, refer to Figure 2 The addition circuit includes a third operational amplifier U3, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a tenth resistor R10.

[0109] In the embodiments of this application, the specific circuit structure of the addition operation circuit is as follows: Figure 2 As shown, it consists of a third operational amplifier U3 and four resistors. The four resistors are the seventh resistor R7, the eighth resistor R8, the ninth resistor R9, and the tenth resistor R10, which form an addition and subtraction operation structure around the third operational amplifier U3.

[0110] The third operational amplifier U3 can refer to the core active device in the addition circuit, which is used to perform addition and subtraction operations on multiple input voltages.

[0111] The seventh resistor R7 can refer to the resistor connected between the reference voltage and the inverting input of the third operational amplifier U3.

[0112] The eighth resistor R8 can refer to the resistor connected between the output of the filter circuit and the inverting input of the third operational amplifier U3.

[0113] The ninth resistor R9 can refer to the feedback resistor connected between the inverting input and output of the third operational amplifier U3.

[0114] The tenth resistor R10 can refer to the resistor connected between the bias voltage and the non-inverting input of the third operational amplifier U3.

[0115] The inverting input of the third operational amplifier U3 receives the reference voltage via the seventh resistor R7, and the filtered temperature sampling voltage via the eighth resistor R8. It is also connected to the output of the third operational amplifier U3 via the ninth resistor R9.

[0116] In this embodiment, the inverting input of the third operational amplifier U3 is connected to a preset reference voltage via a seventh resistor R7, and simultaneously connected to a filtered temperature sampling voltage from a filter circuit via an eighth resistor R8. The two voltage signals converge at the inverting input. The inverting input is also connected to the output of the third operational amplifier U3 via a ninth resistor R9, forming a negative feedback closed-loop circuit to stabilize the operating state of the operational amplifier.

[0117] The non-inverting input of the third operational amplifier U3 receives the bias voltage through the tenth resistor R10.

[0118] In this embodiment, the non-inverting input of the third operational amplifier U3 is connected to a preset bias voltage through the tenth resistor R10 to provide DC operating bias for the third operational amplifier U3, ensuring that the operational amplifier operates in the linear amplification region.

[0119] The third operational amplifier U3 is used to subtract the reference voltage from the bias voltage, and then subtract the filtered temperature sampling voltage to obtain the compensation reference voltage, which is then output at the output terminal of the third operational amplifier U3.

[0120] In this embodiment, the third operational amplifier U3 performs calculations on the voltages connected to the non-inverting and inverting input terminals. The calculation relationship is: subtract the reference voltage connected to the inverting input terminal and the filtered temperature sampling voltage from the bias voltage at the non-inverting input terminal. When the temperature rises, the filtered temperature sampling voltage increases, and the compensation reference voltage decreases accordingly, thereby reducing the drive current to suppress the temperature rise. The calculated compensation reference voltage is output from the output terminal of the third operational amplifier U3 to the control terminal of the switching transistor Q1.

[0121] In a practical implementation, in the addition circuit, the resistance values ​​of the seventh resistor R7, the eighth resistor R8, and the ninth resistor R9 can be 10KΩ, and the resistance value of the tenth resistor R10 can be 3.3KΩ. The reference voltage can be set to 1V, and the bias voltage can be set to 2.2V.

[0122] The operation of the addition circuit is that the compensation reference voltage equals the bias voltage minus the sum of the reference voltage and the filtered temperature sampling voltage. At room temperature, the forward voltage difference of switch Q1 is 0.02V. After differential amplification and filtering, the filtered temperature sampling voltage is 0.2V. At this point, the compensation reference voltage is 2.2V minus 1V and then minus 0.2V, equaling 1.0V. At high temperature, the forward voltage difference of switch Q1 increases to 0.04V, and the filtered temperature sampling voltage is 0.4V. At this point, the compensation reference voltage is 2.2V minus 1V and then minus 0.4V, equaling 0.8V. The increase in temperature causes the compensation reference voltage to decrease from 1.0V to 0.8V. The driver module accordingly reduces the drive current, thereby suppressing further rise in the LED junction temperature and achieving temperature feedforward compensation.

[0123] This application uses a third operational amplifier U3, along with resistors R7, R8, R9, and R10, to form an addition / subtraction circuit. This circuit subtracts the reference voltage and the filtered temperature sampling voltage from the bias voltage to generate a compensation reference voltage, which is then output to the control terminal of the switching transistor Q1. When the temperature rises, the filtered temperature sampling voltage increases, and the compensation reference voltage automatically decreases, thus reducing the drive current in advance to suppress junction temperature rise. This solves the problems of lag in temperature compensation and unstable brightness in existing solutions, achieving pure hardware temperature feedforward compensation and adaptive brightness of the LED across the entire temperature range.

[0124] In practical implementation, when the vehicle-mounted LED is working, the forward voltage difference VDS of the switching transistor Q1 increases with the junction temperature. The forward voltage difference VDS is the difference between the drain voltage VD and the source voltage VS of the switching transistor Q1. The differential amplifier circuit accurately acquires and amplifies the forward voltage difference VDS through a differential amplification architecture, outputting a positive temperature sampling voltage Vtemp that is linearly corresponding to the junction temperature of the LED. The higher the temperature, the larger the temperature sampling voltage Vtemp, thus achieving accurate acquisition of the temperature signal.

[0125] After the temperature sampling voltage Vtemp is filtered to remove high-frequency noise, it enters the inverting input of the third operational amplifier U3 in the adder circuit. It is inversely superimposed with the preset reference voltage Vref. The compensation weight is set by the resistance ratio of the seventh resistor R7, the eighth resistor R8, and the ninth resistor R9. Combined with the bias voltage Vbias connected to the non-inverting input of the third operational amplifier U3, the compensation reference voltage VREF_ADJ is generated.

[0126] The compensation reference voltage VREF_ADJ is fed back to the non-inverting input of the first operational amplifier U1 in the drive module. The inverting input of the first operational amplifier U1 receives the voltage fed back by the first resistor R1. By adjusting the output voltage of the first operational amplifier U1, the gate input voltage of the switching transistor Q1 is adjusted, thereby changing the conduction degree of the switching transistor Q1 and realizing the dynamic correction of the compensation reference voltage VREF_ADJ.

[0127] The core logic is that as temperature rises, the temperature sampling voltage Vtemp increases, enhancing the reverse attenuation effect of the addition circuit and decreasing the compensation reference voltage VREF_ADJ. This, in turn, causes the driver module to reduce the drive current, achieving temperature feedforward compensation for the LED's full-temperature-range brightness adaptation and proactively suppressing the impact of temperature changes on brightness. The entire circuit uses only pure hardware proportional calculations, resulting in a simple structure and a response time of less than 10 microseconds.

[0128] The operation steps of the feedforward compensation module are as follows: After power-on, the reference voltage Vref outputs a stable reference voltage. The non-inverting input of the third operational amplifier U3 is connected to the bias voltage VBIAS through the tenth resistor R10 to complete the module initialization. The second operational amplifier U2 collects the drain voltage VD and source voltage VS of the switching transistor Q1 in real time. Through differential amplification, it outputs a temperature sampling voltage Vtemp that is linearly positively correlated with the junction temperature of the LED. The temperature sampling voltage Vtemp is fed into the third operational amplifier U3 after passing through the RC filter circuit composed of the sixth resistor R6 and the first capacitor C1. The third operational amplifier U3 receives the reference voltage Vref and the filtered temperature sampling voltage Vtemp, and dynamically corrects the reference voltage by performing an inverse proportional superposition operation and setting the compensation weight according to the resistance ratio of the seventh resistor R7, the eighth resistor R8, and the ninth resistor R9. The third operational amplifier U3 outputs the compensation reference voltage VREF_ADJ, which is sent to the driver module in real time to provide a reference for the current adjustment of the driver module, realize temperature feedforward compensation, and ensure the brightness stability of the LED across the entire temperature range.

[0129] Reference Figure 3 The diagram shows a circuit diagram of a voltage detection circuit and a slope detection circuit provided in an embodiment of this application.

[0130] Optionally, refer to Figure 3 The signal acquisition module includes a voltage detection circuit and a slope detection circuit; The specific circuit structure of the signal acquisition module is as follows: Figure 3 As shown, it consists of two independent detection circuits: a voltage detection circuit and a slope detection circuit. The voltage detection circuit is responsible for collecting the voltage information across the LED D1, while the slope detection circuit is responsible for extracting the rate of change of the drive current. The two signals together provide a basis for subsequent fault diagnosis.

[0131] Among them, the voltage detection circuit can refer to the circuit used to collect the voltage across the light-emitting diode and perform differential sampling.

[0132] A slope detection circuit can refer to a circuit used to differentiate current sampling signals and extract the rate of change of current.

[0133] The first input terminal of the voltage detection circuit is connected to the anode of the LED, and the second input terminal of the voltage detection circuit is connected to the cathode of the LED. The voltage detection circuit is used to obtain the voltage across the LED and perform differential sampling on the voltage across the LED, and outputs a voltage signal.

[0134] In this embodiment, the voltage detection circuit has two input terminals. The first input terminal is connected to the anode of the LED, and the second input terminal is connected to the cathode of the LED. The voltage detection circuit acquires the voltage difference between the anode and cathode of the LED using differential sampling, and outputs a terminal voltage signal after processing. The terminal voltage signal remains relatively stable when the LED is working normally. However, when the LED experiences an open-circuit or short-circuit fault, the terminal voltage signal drops significantly. Therefore, the terminal voltage signal is an important basis for judging load faults.

[0135] Among them, the terminal voltage signal can refer to the voltage signal obtained by differential sampling of the voltage difference between the anode and cathode of the light-emitting diode, which is used to reflect the working status of the light-emitting diode.

[0136] The input terminal of the slope detection circuit is connected to the current sampling node. The slope detection circuit is used to acquire the current sampling signal, perform differentiation processing on the current sampling signal, and output the slope signal.

[0137] In this embodiment, the input of the slope detection circuit is connected to the current sampling node between the switching transistor and the first resistor, from which a current sampling signal reflecting the magnitude of the drive current is obtained. The slope detection circuit performs differentiation processing on the current sampling signal, converting the rate of change of current over time into a corresponding voltage signal, i.e., the slope signal. When the drive current undergoes a sudden and abrupt change, such as a short circuit or a loose connection in the wiring harness, the slope signal will increase sharply. Therefore, the slope signal is a key basis for detecting instantaneous faults.

[0138] The slope signal can refer to the voltage signal obtained after differentiating the current sampling signal, which reflects the rate of change of the driving current over time.

[0139] This application uses a voltage detection circuit to differentially sample the voltage across the LED to obtain a terminal voltage signal, and a slope detection circuit to differentiate the current sampling signal to obtain a slope signal. These two signals together provide multi-dimensional evidence for fault diagnosis. The terminal voltage signal can reflect load faults such as open circuits and short circuits, while the slope signal can capture sudden current changes such as short circuits and loose connections in wiring harnesses. This solves the problem of existing solutions having only one signal acquisition dimension and being unable to accurately identify instantaneous faults, achieving comprehensive acquisition and accurate extraction of fault characteristic signals.

[0140] Optionally, the voltage detection circuit includes a fourth operational amplifier U4, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, and a fourteenth resistor R14.

[0141] The specific circuit structure of the voltage detection circuit is as follows: Figure 3 As shown, it consists of a fourth operational amplifier U4 and four resistors. The four resistors are the eleventh resistor R11, the twelfth resistor R12, the thirteenth resistor R13, and the fourteenth resistor R14, which form a differential sampling structure around the fourth operational amplifier U4.

[0142] Among them, the fourth operational amplifier U4 can refer to the core active device in the voltage detection circuit, which is used to differentially sample the voltage across the light-emitting diode.

[0143] The eleventh resistor R11 can refer to the resistor connected between the anode of the light-emitting diode D1 and the non-inverting input terminal of the fourth operational amplifier U4.

[0144] The twelfth resistor R12 can refer to the resistor connected between the cathode of the light-emitting diode D1 and the inverting input of the fourth operational amplifier U4.

[0145] The thirteenth resistor R13 can refer to the feedback resistor connected between the non-inverting input and output terminals of the fourth operational amplifier U4.

[0146] The fourteenth resistor R14 can refer to the resistor connected between the inverting input terminal of the fourth operational amplifier U4 and ground.

[0147] The non-inverting input of the fourth operational amplifier U4 is connected to the anode of the light-emitting diode D1 via the eleventh resistor R11, and is connected to the output of the fourth operational amplifier U4 via the thirteenth resistor R13.

[0148] In this embodiment, the non-inverting input of the fourth operational amplifier U4 is connected to the anode of the light-emitting diode D1 via the eleventh resistor R11 to receive the anode voltage. Simultaneously, this non-inverting input is also connected to the output of the fourth operational amplifier U4 via the thirteenth resistor R13, forming a positive feedback path. The eleventh and thirteenth resistors R11 and R13 together determine the signal gain of the non-inverting input.

[0149] The inverting input of the fourth operational amplifier U4 is connected to the cathode of the light-emitting diode D1 via the twelfth resistor R12, and grounded via the fourteenth resistor R14.

[0150] The inverting input of the fourth operational amplifier U4 is connected to the cathode of the light-emitting diode D1 through the twelfth resistor R12, receiving the cathode voltage. Simultaneously, this inverting input is also connected to ground through the fourteenth resistor R14, forming the reference potential for the inverting input. The twelfth and fourteenth resistors together determine the signal gain of the inverting input.

[0151] The fourth operational amplifier U4 is used to differentially sample the voltage across the light-emitting diode D1 to obtain the terminal voltage signal, and outputs the terminal voltage signal at the output terminal of the fourth operational amplifier U4.

[0152] The fourth operational amplifier U4 receives the voltage across the anode and cathode of LED D1 and performs differential sampling on the voltage difference between the two input terminals. When the resistances of the eleventh resistor R11, twelfth resistor R12, thirteenth resistor R13, and fourteenth resistor R14 are equal, the amplification factor of the voltage detection circuit is 1, and the terminal voltage signal is equal to the voltage difference between the anode and cathode of LED D1. The terminal voltage signal Vled is output from the output terminal of the fourth operational amplifier U4 to the fault diagnosis module.

[0153] In a practical implementation, in the voltage detection circuit, the resistance values ​​of the eleventh resistor R11, the twelfth resistor R12, the thirteenth resistor R13, and the fourteenth resistor R14 can all be 10KΩ. With all four resistors having equal resistance values, the voltage detection circuit performs a one-to-one differential sampling of the voltage across the LED, and the terminal voltage signal Vled is equal to the voltage difference between the anode and cathode of the LED.

[0154] This application uses a fourth operational amplifier U4, along with eleventh resistor R11, twelfth resistor R12, thirteenth resistor R13, and fourteenth resistor R14, to construct a differential sampling circuit. This circuit performs one-to-one differential sampling of the voltage across the anode and cathode of the LED, outputting a terminal voltage signal. With all four resistors having equal resistance values, the differential sampling structure effectively suppresses common-mode interference, ensuring the terminal voltage signal accurately reflects the actual operating voltage of the LED. This solves the problems of low voltage detection accuracy and susceptibility to interference in existing solutions, achieving high-precision, interference-resistant terminal voltage signal acquisition.

[0155] Optionally, refer to Figure 3 The slope detection circuit includes the fifth operational amplifier U5, the input capacitor C2, the fifteenth resistor R15, and the sixteenth resistor R16.

[0156] The specific circuit structure of the slope detection circuit is as follows: Figure 3 As shown, it consists of a fifth operational amplifier U5, an input capacitor C2, and two resistors. The two resistors are the fifteenth resistor R15 and the sixteenth resistor R16, which form an active differentiating circuit structure around the fifth operational amplifier U5.

[0157] Among them, the fifth operational amplifier U5 can refer to the core active device in the slope detection circuit, which is used to differentiate the current sampling signal.

[0158] The input capacitor C2 can refer to the capacitor connected between the current sampling node and the inverting input of the fifth operational amplifier U5, which is used to couple the current sampling signal and perform differentiation operations on the signal.

[0159] The fifteenth resistor R15 can refer to the feedback resistor connected between the inverting input and output terminals of the fifth operational amplifier U5, which, together with the input capacitor C2, determines the differential time constant.

[0160] The sixteenth resistor R16 can refer to the pull-down resistor connected between the phase input terminal of the fifth operational amplifier U5 and ground, providing a DC reference potential for the non-inverting input terminal.

[0161] The inverting input of the fifth operational amplifier U5 is connected to the current sampling node via the input capacitor C2, and is connected to the output of the fifth operational amplifier U5 via the fifteenth resistor R15.

[0162] In this embodiment, the inverting input of the fifth operational amplifier U5 is connected to the current sampling node between the switching transistor and the first resistor via an input capacitor C2. The current sampling signal is coupled to the inverting input through the input capacitor C2. Simultaneously, the inverting input is also connected to the output of the fifth operational amplifier U5 via a fifteenth resistor R15, forming a negative feedback path. The input capacitor C2 and the fifteenth resistor R15 together determine the time constant and gain of the differentiating circuit.

[0163] The non-inverting input of the fifth operational amplifier U5 is connected to ground via the sixteenth resistor R16.

[0164] In this embodiment, the non-inverting input of the fifth operational amplifier U5 is connected to ground through the sixteenth resistor R16, providing a stable DC reference potential for the non-inverting input and ensuring that the operational amplifier operates in the linear region.

[0165] The fifth operational amplifier U5 is used to differentiate the current sampling signal to obtain the slope signal, and outputs the slope signal at the output terminal of the fifth operational amplifier U5.

[0166] In this embodiment, the fifth operational amplifier U5, input capacitor C2, and fifteenth resistor R15 constitute an active differentiating circuit to perform differentiation on the current sampling signal, converting the rate of change of the driving current over time into a corresponding voltage signal. When the driving current is stable, the slope signal is zero or close to zero; when the driving current undergoes a sudden, instantaneous change, the slope signal outputs a voltage pulse proportional to the rate of change. The slope signal is output from the output terminal of the fifth operational amplifier U5 to the fault detection module for detecting instantaneous faults such as short circuits and loose connections in the wiring harness.

[0167] In the specific implementation, the resistance of the fifteenth resistor R15 can be 10KΩ, the resistance of the sixteenth resistor R16 can be 10KΩ, and the capacitance of the input capacitor C2 can be 100nF. The slope detection circuit adopts an active differential amplifier structure. The current sampling signal Isense provided by the current sampling node is connected to the inverting input of the fifth operational amplifier U5. The current sampling signal Isense is differentiated to convert the rate of change of the driving current over time, i.e., the slope, into a corresponding voltage signal, resulting in the slope signal. The slope signal Slope is directly sent to the fault discrimination module, where it, together with the terminal voltage signal Vled and the current sampling signal Isense, is used to identify sudden current change faults caused by short circuits, loose wiring harness connections, etc.

[0168] This application utilizes an active differentiating circuit constructed from a fifth operational amplifier U5, input capacitor C2, fifteenth resistor R15, and sixteenth resistor R16 to differentiate the current sampling signal, converting the rate of change of the driving current into a slope signal output. When the driving current experiences a sudden, abrupt change, the slope signal output is a voltage pulse proportional to the rate of change, enabling rapid detection of transient fault characteristics such as short circuits and loose connections in the wiring harness. This solves the problems of existing solutions lacking an active amplification structure, resulting in the inability to identify weak slope signals and the response delay in software processing, achieving rapid and accurate detection of transient faults.

[0169] Reference Figure 4 The diagram shows a circuit diagram of a fault detection module provided in an embodiment of this application.

[0170] Optionally, refer to Figure 4 The fault detection module includes a first comparator U6, a second comparator U7, a third comparator U8, an OR gate U10, an inverter U9, an AND gate U11, and an encoding output circuit.

[0171] The specific circuit structure of the fault diagnosis module is as follows: Figure 4As shown, the circuit consists of three comparators, three logic gates, and an encoding output circuit. The three comparators are designated as Comparator U6, Comparator U7, and Comparator U8. The three logic gates are an OR gate U10, an inverter U9, and an AND gate U11. The comparators compare the analog signal with a preset threshold and output a digital level signal. The logic gates perform combinational logic operations on multiple fault signals to achieve fault classification. The encoding output circuit determines and outputs the fault category based on the output of the logic gates.

[0172] Among them, the first comparator U6 can refer to a comparator used to compare the current sampling signal with the overcurrent threshold voltage and output an overcurrent fault signal.

[0173] The second comparator U7 can refer to a comparator used to compare the slope signal with the slope threshold voltage, and outputs a slope fault signal.

[0174] The third comparator U8 can refer to a comparator used to compare the undervoltage threshold voltage with the terminal voltage signal, and outputs a load fault signal.

[0175] Inverter U9 can refer to a logic gate used to logically invert a slope fault signal.

[0176] OR gate U10 can refer to a logic gate used to perform a logical OR operation on overcurrent fault signals and slope fault signals.

[0177] AND gate U11 can refer to a logic gate used to perform a logical AND operation on an overcurrent fault signal and an inverted slope fault signal.

[0178] The coded output circuit can refer to a circuit used to determine and output the fault category based on load fault signals, severe fault signals, and mild overload signals.

[0179] The non-inverting input of the first comparator U6 is connected to the current sampling node to acquire the current sampling signal Isense. The inverting input of the first comparator U6 is used to receive the preset overcurrent threshold voltage Vth1. The first comparator U6 is used to output an overcurrent fault signal based on the comparison result between the current sampling signal Isense and the overcurrent threshold voltage Vth1.

[0180] In this embodiment, the non-inverting input of the first comparator U6 is connected to a current sampling signal, and the inverting input is connected to a preset overcurrent threshold voltage Vth1. When the drive current is normal, the current sampling signal is lower than the overcurrent threshold voltage, and the first comparator U6 outputs an overcurrent fault signal at a low level. When the drive current exceeds the overcurrent threshold, the current sampling signal is higher than the overcurrent threshold voltage, and the first comparator U6 outputs an overcurrent fault signal at a high level.

[0181] The non-inverting input of the second comparator U7 is connected to the output of the slope detection circuit to acquire the slope signal Slope. The inverting input of the second comparator U7 is used to receive the preset slope threshold voltage Vth2. The second comparator U7 is used to output a slope fault signal based on the comparison result between the slope signal Slope and the slope threshold voltage Vth2.

[0182] In this embodiment, the non-inverting input of the second comparator U7 is connected to a slope signal Slope, and the inverting input is connected to a preset slope threshold voltage Vth2. When the drive current changes gradually, the slope signal Slope is lower than the slope threshold voltage Vth2, and the second comparator U7 outputs a slope fault signal at a low level. When a short circuit or a loose connection in the wiring harness causes a sudden and abrupt change in current, the slope signal Slope is higher than the slope threshold voltage Vth2, and the second comparator U7 outputs a slope fault signal at a high level.

[0183] The non-inverting input of the third comparator U8 is used to receive the preset undervoltage threshold voltage Vth3. The inverting input of the third comparator U8 is connected to the output of the voltage detection circuit to obtain the terminal voltage signal Vled. The third comparator U8 is used to output a load fault signal based on the comparison result between the undervoltage threshold voltage Vth3 and the terminal voltage signal Vled.

[0184] In this embodiment, the non-inverting input of the third comparator U8 is connected to a preset undervoltage threshold voltage Vth3, and the inverting input is connected to the terminal voltage signal Vled. When the LED is working normally, the terminal voltage signal Vled is higher than the undervoltage threshold voltage Vth3, the voltage at the non-inverting input of the third comparator U8 is lower than the voltage at the inverting input, and the output load fault signal is low. When the LED experiences an open circuit or short circuit, causing a significant drop in terminal voltage, the terminal voltage signal Vled is lower than the undervoltage threshold voltage Vth3, the voltage at the non-inverting input of the third comparator U8 is higher than the voltage at the inverting input, and the output load fault signal is high.

[0185] The first input terminal of OR gate U10 is connected to the output terminal of the first comparator U6 to acquire the overcurrent fault signal. The second input terminal of OR gate U10 is connected to the output terminal of the second comparator U7 to acquire the slope fault signal. OR gate U10 is used to output a severe fault signal based on the overcurrent fault signal and the slope fault signal.

[0186] In this embodiment, the two inputs of OR gate U10 receive an overcurrent fault signal and a slope fault signal, respectively. When at least one of the overcurrent fault signal and the slope fault signal is high, OR gate U10 outputs a critical fault signal that is high. When both the overcurrent fault signal and the slope fault signal are low, OR gate U10 outputs a critical fault signal that is low. The critical fault signal is used to trigger shutdown protection to prevent the fault from escalating.

[0187] The input of inverter U9 is connected to the output of the second comparator U7 to acquire the slope fault signal. Inverter U9 is used to invert the slope fault signal and output the inverted slope fault signal.

[0188] In this embodiment, the input of inverter U9 receives a slope fault signal and performs a logical inversion on the slope fault signal. When the slope fault signal is high, inverter U9 outputs a low-level inverted slope fault signal. When the slope fault signal is low, inverter U9 outputs a high-level inverted slope fault signal, indicating no current surge.

[0189] The first input terminal of AND gate U11 is connected to the output terminal of the first comparator U6 to obtain the overcurrent fault signal. The second input terminal of AND gate U11 is connected to the output terminal of inverter U9 to obtain the inverted slope fault signal. AND gate U11 is used to output a mild overload signal based on the overcurrent fault signal and the inverted slope fault signal.

[0190] In this embodiment, the two inputs of AND gate U11 receive an overcurrent fault signal and an inverted slope fault signal, respectively. When both the overcurrent fault signal and the inverted slope fault signal are high (i.e., there is no current surge), AND gate U11 outputs a slight overload signal at a high level. Otherwise, AND gate U11 outputs a slight overload signal at a low level. The slight overload signal triggers current reduction and limiting protection, preventing the lamps from shutting off and maintaining continuous lighting.

[0191] The input terminals of the encoding output circuit are connected to the output terminals of the third comparator U8, the OR gate U10, and the AND gate U11, respectively, to acquire load fault signals, severe fault signals, and mild overload signals, and output the fault category of the light-emitting diode based on the load fault signals, severe fault signals, and mild overload signals.

[0192] In this embodiment, the encoding output circuit receives three fault status signals, including a load fault signal from the third comparator U8, a severe fault signal from the OR gate U10, and a slight overload signal from the AND gate U11. The encoding output circuit performs logical combination and encoding on these three signals, and outputs the fault category of the light-emitting diode according to a preset fault mapping relationship, including normal operating state, short circuit fault, open circuit fault, slight overload fault, and impulse overcurrent fault.

[0193] In the specific implementation, refer to Figure 4The fault detection module includes a first comparator U6, a second comparator U7, a third comparator U8, an OR gate U10, an inverter U9, an AND gate U11, and an encoded output circuit. The overcurrent threshold voltage Vth1 can be set to 1.3V, corresponding to a drive current of 1.3A. The slope threshold voltage Vth2 can be set to 0.4V, corresponding to a current change rate of 400A / s. The undervoltage threshold voltage Vth3 can be set to 2.4V. Taking the normal voltage drop of a light-emitting diode (LED) as an example, a voltage drop to 75% of the normal value is considered abnormal. The fault detection module follows the design principle of high-level active for faults and low-level active for normal operation.

[0194] The non-inverting input of the first comparator U6 is connected to the current sampling signal Isense, and the inverting input is connected to the overcurrent threshold voltage Vth1. Under normal operating conditions, the current sampling signal Isense is less than the overcurrent threshold voltage Vth1, and the first comparator U6 outputs a low level. During an overcurrent event, the current sampling signal Isense is greater than the overcurrent threshold voltage Vth1, and the first comparator U6 outputs a high level, triggering overcurrent protection.

[0195] The non-inverting input of the second comparator U7 is connected to the slope signal Slope, and the inverting input is connected to the slope threshold voltage Vth2. Under normal operating conditions, the drive current changes gradually, the slope signal Slope is less than the slope threshold voltage Vth2, and the second comparator U7 outputs a low level. When a short circuit or loose connection in the wiring harness causes a sudden change in current, the slope signal Slope is greater than the slope threshold voltage Vth2, the second comparator U7 outputs a high level, triggering instantaneous fault protection.

[0196] The non-inverting input of the third comparator U8 is connected to the undervoltage threshold voltage Vth3, and the inverting input is connected to the terminal voltage signal Vled. When the LED is operating normally, the terminal voltage signal Vled remains at a high potential, exceeding the undervoltage threshold voltage Vth3. At this time, the voltage at the non-inverting input is lower than the voltage at the inverting input, and the third comparator U8 outputs a low level. When the LED is open-circuited or short-circuited, the terminal voltage signal Vled drops significantly, falling below the undervoltage threshold voltage Vth3. At this time, the voltage at the non-inverting input is higher than the voltage at the inverting input, and the third comparator U8 outputs a high level, achieving unified detection of load faults.

[0197] The slope fault signal output by the second comparator U7 is divided into two paths. One path is directly connected to the OR gate U10 to identify serious faults; the other path is connected to the inverter U9 to reverse the level. The inverted signal is then connected to the AND gate U11 to screen for stable operating conditions without current surges, meeting the requirements for determining slight overload.

[0198] The judgment of serious faults adopts the OR gate combination method. The overcurrent fault signal output by the first comparator U6 and the slope fault signal output by the second comparator U7 are connected to the OR gate U10. Taking advantage of the characteristic that the output of the OR gate is high when any input is high, as long as any high-risk fault occurs, the OR gate U10 immediately outputs a serious fault signal, triggering the shutdown protection, quickly shutting down or isolating the fault channel, and preventing the fault from escalating.

[0199] The judgment of minor overload fault adopts the AND gate combination method. The overcurrent fault signal output by the first comparator U6 and the slope fault signal after inversion output by the inverter U9 are connected to the AND gate U11. Taking advantage of the characteristic that the output of the AND gate is high only when all inputs are high, the AND gate U11 outputs a minor overload signal only when both the overcurrent and the current surge conditions are met simultaneously, triggering the current reduction and current limiting protection, without turning off the lamps, ensuring the continuity of vehicle lighting, and realizing the working condition screening.

[0200] The load fault is identified using a pure hardware method that combines independent judgment with combination differentiation. The load fault signal output by the third comparator U8 is directly connected to the encoding output circuit to achieve independent judgment of the load fault. This facilitates the subsequent differentiation of open circuit and short circuit by combining overcurrent fault signal and slope fault signal. At the same time, the load fault signal is output for fault isolation and reporting, which is convenient for later maintenance and troubleshooting.

[0201] This application uses a first comparator U6, a second comparator U7, and a third comparator U8 to perform threshold comparisons on the current sampling signal, slope signal, and terminal voltage signal, respectively, outputting overcurrent fault signal, slope fault signal, and load fault signal. Then, through combinational logic operations using an OR gate U10, an inverter U9, and an AND gate U11, it distinguishes between a severe fault signal and a mild overload signal. Finally, the encoding output circuit determines and outputs the fault category of the LED based on the three fault status signals. This solves the problem in existing solutions where a single comparator cannot distinguish fault type and level, and any fault may lead to unnecessary control of the lamps, thus affecting lighting and driving safety. It achieves fault classification and differentiated protection, balancing the continuity and safety of driving lighting.

[0202] Optionally, the step of outputting the fault category of the LED based on the load fault signal, the severe fault signal, and the mild overload signal includes: S11, if the serious fault signal is low, the minor overload signal is low, and the load fault signal is low, then the output LED of the encoding output circuit is in normal working condition. S12, if the serious fault signal is high level, the minor overload signal is low level, and the load fault signal is high level, then the output LED of the encoding output circuit is short-circuit fault; S13, if the serious fault signal is low level, the minor overload signal is low level, and the load fault signal is high level, then the output LED of the encoding output circuit is open circuit fault. S14, if the minor overload signal is high, the output LED of the encoding output circuit indicates a minor overload fault. S15, if the serious fault signal is high level, the minor overload signal is low level, and the load fault signal is low level, then the output LED of the encoding output circuit indicates an impulse overcurrent fault.

[0203] In this embodiment, if the severe fault signal is low, the mild overload signal is low, and the load fault signal is low, when all three fault status signals are low, it indicates that the drive current has not exceeded the overcurrent threshold and the current change signal is low, then the output LED of the encoding output circuit is in normal working condition.

[0204] Specifically, when all three fault status signals are low, it indicates that the drive current has not exceeded the overcurrent threshold, the current changes smoothly without sudden changes, the terminal voltage remains within the normal range, the LED is in normal working condition, and the encoding output circuit outputs the normal working condition code.

[0205] In this embodiment of the application, if the serious fault signal is high level, the minor overload signal is low level, and the load fault signal is high level, then the output LED of the encoding output circuit indicates a short circuit fault.

[0206] In other words, a high level for a severe fault signal indicates that at least one of overcurrent or sudden current change has occurred; a low level for a minor overload signal indicates that the minor overload condition is not met; and a high level for a load fault signal indicates that the terminal voltage has dropped significantly. When all three conditions are met, the LED is determined to be short-circuited, and the encoding output circuit outputs a short-circuit fault code.

[0207] In this embodiment of the application, if the serious fault signal is low level, the mild overload signal is low level, and the load fault signal is high level, then the output LED of the encoding output circuit is open circuit fault.

[0208] Specifically, when the serious fault signal is low, it indicates no overcurrent and no sudden current change; when the mild overload signal is low, and when the load fault signal is high, it indicates a significant drop in terminal voltage. When all three conditions are met, it is determined to be an open circuit fault of the LED, and the encoding output circuit outputs an open circuit fault code.

[0209] In this embodiment of the application, if the minor overload signal is high, the output LED of the encoding output circuit indicates a minor overload fault.

[0210] Specifically, when the light overload signal is high, it indicates that the drive current exceeds the overcurrent threshold but there is no current surge. Regardless of the state of the load fault signal and the serious fault signal, it is determined to be a light overload fault of the LED, and the encoding output circuit outputs a light overload fault code.

[0211] In this embodiment of the application, if the severe fault signal is high level, the mild overload signal is low level, and the load fault signal is low level, then the output LED of the encoding output circuit indicates an impulse overcurrent fault.

[0212] When the serious fault signal is high, it indicates that at least one of overcurrent or sudden current change has occurred. When the minor overload signal is low, it indicates that the minor overload judgment condition is not met. When the load fault signal is low, it indicates that the terminal voltage is normal. When all three conditions are met, it is judged as an LED impulse overcurrent fault, and the encoding output circuit outputs the impulse overcurrent fault code.

[0213] In the specific implementation, the truth table and corresponding fault categories of the fault discrimination module are as follows: The overcurrent fault signal is denoted as A, where A=1 indicates overcurrent and A=0 indicates no overcurrent. The slope fault signal is denoted as B, where B=1 indicates that the current slope exceeds the threshold and B=0 indicates that the current slope does not exceed the threshold. The load fault signal is denoted as C, where C=1 indicates that the terminal voltage has dropped, i.e., the load is abnormal, and C=0 indicates that the terminal voltage is normal.

[0214] When A=0, B=0, and C=0, the corresponding OR gate U10 outputs A+B=0, and the AND gate U11 outputs A· =0, C=0, the encoding output circuit is determined to be in normal working condition. Among them, This indicates the inversion of B.

[0215] When A=1, B=1, and C=1, the corresponding OR gate U10 outputs A+B=1, and the AND gate U11 outputs A· =0, C=1, the encoding output circuit judges it as a short circuit fault and triggers the emergency shutdown protection.

[0216] When A=0, B=0, and C=1, the corresponding OR gate U10 outputs A+B=0, and the AND gate U11 outputs A· =0, C=1, the encoding output circuit is identified as having an open circuit fault, triggering a shutdown alarm.

[0217] When A=1, B=0, and C=0, the corresponding OR gate U10 outputs A+B=0, and the AND gate U11 outputs A· =1, C=0, the encoding output circuit judges it as a slight overload fault, triggers current reduction and current limiting, and maintains lighting.

[0218] When A=1, B=0, and C=1, the corresponding OR gate U10 outputs A+B=0, and the AND gate U11 outputs A· =1, C=1, the encoding output circuit judges it as a slight overload fault, triggers current reduction and current limiting, and maintains lighting.

[0219] When A=1, B=1, and C=0, the corresponding OR gate U10 outputs A+B=1, and the AND gate U11 outputs A· =0, C=0, the encoding output circuit judges it as an impulse overcurrent fault and triggers emergency buffer current limiting.

[0220] When A=0, B=1, and C=0, this working condition is impossible to occur in actual work.

[0221] When A=0, B=1, and C=1, this working condition is impossible to occur in actual work.

[0222] Based on the above judgment logic, when A· When A+B=1, current reduction and current limiting protection is triggered; when A+B=1, emergency shutdown or emergency buffer current limiting protection is triggered. The encoding output circuit combines and encodes the three signals output by OR gate U10, AND gate U11 and the third comparator U8, mapping different fault conditions to a unique digital code and reporting them, thereby achieving accurate differentiation and hierarchical processing of fault types.

[0223] Multiple independent fault status signals output by the fault discrimination module are synchronously connected to the input of the encoding output circuit. Based on its hardware-defined logic, the encoding output circuit automatically compiles fault signals of different types and severity levels into standardized digital coded signals according to preset fault priorities. It maps different fault conditions, such as minor overload faults, impact overcurrent faults, open circuit faults, and short circuit faults, to unique digital codes and reports them. The encoding output circuit achieves accurate differentiation, real-time acquisition, and digital aggregation and reporting of various hardware fault types, providing the main control unit (MCU) with a precise and reliable underlying fault data source for performing hierarchical current limiting, output shutdown, fault storage, instrument fault indication, and vehicle fault diagnosis and tracing.

[0224] This application uses three comparators to detect overcurrent, sudden changes in current slope, and load voltage drops. Then, through a combination of OR gates, inverters, and AND gates, it classifies faults into two levels: severe fault and minor overload. Finally, the encoding output circuit outputs five fault categories—normal operation, short circuit, open circuit, minor overload, and impulse overcurrent—based on a truth table combination of the three fault status signals. This solves the problems of existing solutions that use a single comparator, which cannot distinguish fault type and level, and where any fault may lead to unnecessary control of the lighting fixtures, thus affecting lighting and driving safety. It achieves fault classification and differentiated protection, balancing the continuity and safety of vehicle lighting.

[0225] One embodiment of this application also provides a vehicle including the drive circuit described above. The drive circuit drives LED lamps on the vehicle, providing constant current drive to the LEDs, and features temperature feedforward compensation, signal acquisition, and fault classification and discrimination functions. The drive circuit can operate stably over a wide temperature range and in complex electromagnetic environments within the vehicle, automatically adjusting the drive current to maintain stable brightness when the temperature changes, and differentiating fault types and implementing graded protection measures when a fault occurs, preventing sudden lighting interruptions and improving driving safety.

[0226] The above provides a detailed description of the drive circuit and vehicle. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this application. At the same time, those skilled in the art will recognize that there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A driving circuit, characterized in that, The circuit is used to drive light-emitting diodes and includes: a driving module, a feedforward compensation module, a signal acquisition module, and a fault detection module. The driving module is connected in series with the light-emitting diode. The driving module includes a switching transistor and a first resistor. The switching transistor is used to provide driving current to the light-emitting diode. A current sampling node is configured between the switching transistor and the first resistor. The current sampling node is used to provide a current sampling signal that reflects the driving current. The input terminal of the feedforward compensation module is connected to the switching transistor to collect the on-state voltage difference across the switching transistor. The output terminal of the feedforward compensation module is connected to the control terminal of the switching transistor to output a compensation reference voltage based on the on-state voltage difference to compensate for the effect of temperature change on the driving current. The input terminal of the signal acquisition module is connected to both ends of the light-emitting diode and the current sampling node, respectively, for extracting the terminal voltage signal of the light-emitting diode and generating the slope signal of the driving current based on the current sampling signal; The input terminal of the fault discrimination module is connected to the output terminal of the signal acquisition module, and is used to output the fault category of the light-emitting diode based on the terminal voltage signal, the current sampling signal and the slope signal.

2. The driving circuit according to claim 1, characterized in that, The driving module further includes a first operational amplifier; The non-inverting input of the first operational amplifier is used to receive the compensation reference voltage, the inverting input of the first operational amplifier is connected to the current sampling node to acquire the current sampling signal, and the output of the first operational amplifier is connected to the control terminal of the switching transistor. The first operational amplifier is used to control the switching transistor according to the compensation reference voltage and the current sampling signal, so that the switching transistor outputs the drive current.

3. The driving circuit according to claim 1, characterized in that, The feedforward compensation module includes a differential amplifier circuit, a filter circuit, and an addition circuit; The input terminal of the differential amplifier circuit is connected to the drain and source of the switching transistor to acquire the conduction voltage difference, differentially amplify the conduction voltage difference, and output the amplified conduction voltage difference as the temperature sampling voltage. The input terminal of the filtering circuit is connected to the output terminal of the differential amplifier circuit to obtain the temperature sampling voltage, filter the temperature sampling voltage, and output the filtered temperature sampling voltage. The first input terminal of the adder circuit is used to receive a preset reference voltage. The second input terminal of the adder circuit is connected to the output terminal of the filter circuit to obtain the filtered temperature sampling voltage. The third input terminal of the adder circuit is used to receive a preset bias voltage. The output terminal of the adder circuit is connected to the control terminal of the switch. The addition circuit is used to subtract the reference voltage from the bias voltage, and then subtract the filtered temperature sampling voltage to obtain the compensation reference voltage, and output the compensation reference voltage to the control terminal of the switching transistor.

4. The driving circuit according to claim 3, characterized in that, The differential amplifier circuit includes a second operational amplifier, a second resistor, a third resistor, a fourth resistor, and a fifth resistor; The non-inverting input terminal of the second operational amplifier is connected to the drain of the switching transistor via the second resistor, and is also connected to the output terminal of the second operational amplifier via the fourth resistor. The inverting input terminal of the second operational amplifier is connected to the source of the switching transistor via the third resistor and grounded via the fifth resistor; The second operational amplifier is used to differentially amplify the conduction voltage difference, use the amplified conduction voltage difference as the temperature sampling voltage, and output the temperature sampling voltage at the output terminal of the second operational amplifier.

5. The driving circuit according to claim 3, characterized in that, The filter circuit includes a sixth resistor and a first capacitor; The sixth resistor is connected in series between the output terminal of the differential amplifier circuit and the second input terminal of the adder circuit; One end of the first capacitor is connected to the node between the sixth resistor and the second input terminal of the addition circuit, and the other end is grounded; The filtering circuit is used to filter the temperature sampling voltage through the sixth resistor and the first capacitor, and output the filtered temperature sampling voltage.

6. The driving circuit according to claim 3, characterized in that, The addition circuit includes a third operational amplifier, a seventh resistor, an eighth resistor, a ninth resistor, and a tenth resistor; The inverting input terminal of the third operational amplifier receives the reference voltage via the seventh resistor, and receives the filtered temperature sampling voltage via the eighth resistor. It is also connected to the output terminal of the third operational amplifier via the ninth resistor. The non-inverting input of the third operational amplifier receives the bias voltage via the tenth resistor; The third operational amplifier is used to subtract the reference voltage from the bias voltage, and then subtract the filtered temperature sampling voltage to obtain the compensation reference voltage, and output the compensation reference voltage at the output terminal of the third operational amplifier.

7. The driving circuit according to claim 1, characterized in that, The signal acquisition module includes a voltage detection circuit and a slope detection circuit; The first input terminal of the voltage detection circuit is connected to the anode of the light-emitting diode, and the second input terminal of the voltage detection circuit is connected to the cathode of the light-emitting diode. The voltage detection circuit is used to acquire the voltage across the light-emitting diode, perform differential sampling on the voltage across the light-emitting diode, and output the terminal voltage signal. The input terminal of the slope detection circuit is connected to the current sampling node. The slope detection circuit is used to acquire the current sampling signal, perform differentiation processing on the current sampling signal, and output the slope signal.

8. The driving circuit according to claim 7, characterized in that, The voltage detection circuit includes a fourth operational amplifier, an eleventh resistor, a twelfth resistor, a thirteenth resistor, and a fourteenth resistor; The non-inverting input terminal of the fourth operational amplifier is connected to the anode of the light-emitting diode via the eleventh resistor, and is connected to the output terminal of the fourth operational amplifier via the thirteenth resistor; The inverting input terminal of the fourth operational amplifier is connected to the cathode of the light-emitting diode via the twelfth resistor, and grounded via the fourteenth resistor; The fourth operational amplifier is used to differentially sample the voltage across the light-emitting diode to obtain the terminal voltage signal, and output the terminal voltage signal at the output terminal of the fourth operational amplifier.

9. The driving circuit according to claim 7, characterized in that, The slope detection circuit includes a fifth operational amplifier, an input capacitor, a fifteenth resistor, and a sixteenth resistor; The inverting input terminal of the fifth operational amplifier is connected to the current sampling node via the input capacitor, and is connected to the output terminal of the fifth operational amplifier via the fifteenth resistor; The non-inverting input terminal of the fifth operational amplifier is grounded via the sixteenth resistor; The fifth operational amplifier is used to differentiate the current sampling signal to obtain the slope signal, and outputs the slope signal at the output terminal of the fifth operational amplifier.

10. The driving circuit according to claim 1, characterized in that, The fault detection module includes a first comparator, a second comparator, a third comparator, an OR gate, an inverter, an AND gate, and an encoding output circuit. The non-inverting input of the first comparator is connected to the current sampling node to acquire the current sampling signal. The inverting input of the first comparator is used to receive a preset overcurrent threshold voltage. The first comparator is used to output an overcurrent fault signal based on the comparison result between the current sampling signal and the overcurrent threshold voltage. The non-inverting input of the second comparator is connected to the output of the slope detection circuit to acquire the slope signal. The inverting input of the second comparator is used to receive a preset slope threshold voltage. The second comparator is used to output a slope fault signal based on the comparison result between the slope signal and the slope threshold voltage. The non-inverting input of the third comparator is used to receive a preset undervoltage threshold voltage. The inverting input of the third comparator is connected to the output of the voltage detection circuit to acquire the terminal voltage signal. The third comparator is used to output a load fault signal based on the comparison result between the undervoltage threshold voltage and the terminal voltage signal. The first input terminal of the OR gate is connected to the output terminal of the first comparator to obtain the overcurrent fault signal, and the second input terminal of the OR gate is connected to the output terminal of the second comparator to obtain the slope fault signal. The OR gate is used to output a severe fault signal based on the overcurrent fault signal and the slope fault signal. The input terminal of the inverter is connected to the output terminal of the second comparator to acquire the slope fault signal. The inverter is used to invert the slope fault signal and output the inverted slope fault signal. The first input terminal of the AND gate is connected to the output terminal of the first comparator to obtain the overcurrent fault signal. The second input terminal of the AND gate is connected to the output terminal of the inverter to obtain the inverted slope fault signal. The AND gate is used to output a mild overload signal based on the overcurrent fault signal and the inverted slope fault signal. The input terminal of the encoding output circuit is connected to the output terminal of the third comparator, the output terminal of the OR gate, and the output terminal of the AND gate, respectively, for acquiring the load fault signal, the severe fault signal, and the mild overload signal, and outputting the fault category of the light-emitting diode according to the load fault signal, the severe fault signal, and the mild overload signal.

11. The driving circuit according to claim 10, characterized in that, The step of outputting the fault category of the light-emitting diode based on the load fault signal, the severe fault signal, and the mild overload signal includes: If the severe fault signal is low, the mild overload signal is low, and the load fault signal is low, then the encoding output circuit outputs that the light-emitting diode is in normal working condition. If the severe fault signal is high, the mild overload signal is low, and the load fault signal is high, then the encoding output circuit outputs that the light-emitting diode is short-circuit fault. If the severe fault signal is low, the mild overload signal is low, and the load fault signal is high, then the encoding output circuit outputs that the light-emitting diode is open-circuit fault. If the slight overload signal is high, the encoding output circuit outputs that the light-emitting diode is in a slight overload fault. If the severe fault signal is high, the mild overload signal is low, and the load fault signal is low, then the encoding output circuit outputs that the light-emitting diode indicates an impulse overcurrent fault.

12. A vehicle, characterized in that, The vehicle includes the drive circuit as described in claims 1-11.

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