Car lamp constant current control circuit and car lamp controller

Abstract

The invention discloses a vehicle lamp constant current control circuit and a vehicle controller, the circuit comprises a power supply module, an anti-reverse filtering module, a boost module, a control module and a constant current module, the anti-reverse filtering module comprises a plurality of anti-reverse filtering units; each anti-reverse filtering unit comprises an input protection unit, an anti-reverse control chip, a power switch tube and an output filtering unit, the boost module is used for providing power supply voltage required by the constant current module, and the constant current module is used for performing constant current control and fault diagnosis according to driving characteristics of different loads. According to the circuit, a special anti-reverse control circuit is designed for a high-power driving load, accurate overvoltage and undervoltage diagnosis is carried out on each constant-current channel, and the current values of the constant-current channels are controlled by adjusting the PWM duty ratio; the problems that a traditional anti-reverse protection function fails, an existing constant current control mode lacks fine diagnosis, and energy is wasted are solved.

Description

Technical Field

[0001] The invention belongs to the field of vehicle control, and in particular relates to a vehicle light constant current control circuit and a vehicle light controller. Background Art

[0002] At present, almost all car lights use light emitting diodes (LED) as light sources, and their driving modes are mainly divided into constant voltage driving and constant current driving. In order to ensure the stability of light brightness, most manufacturers tend to choose constant current driving. Since a car is equipped with a variety of lamps, such as low beams, position lights, high beams, turn signals, etc., these lamps are usually driven and controlled uniformly by a light driving module. However, the existing constant current driving system has deficiencies in fault detection and self-protection. For example, in terms of overvoltage detection, only when the voltage of the constant current channel exceeds the preset maximum voltage value of all channels, the system will report an overvoltage fault and cut off the output of the channel for protection. Similarly, undervoltage detection also has similar problems, and the system lacks refined control capabilities.

[0003] When the lighting control module needs to drive high-power lamps, that is, the power can reach 150W or even higher, and the current can reach 13A or even higher, the traditional method of using series diodes to prevent reverse polarity is no longer applicable, because excessive current and heat will cause the diode to be damaged, thereby losing the anti-reverse polarity protection function. In addition, the existing constant current control method is relatively rough, and it is impossible to perform refined diagnosis and protection according to the characteristics of each channel driving the light. Specifically, the system will only perform overvoltage protection when the actual output voltage value of the channel reaches the preset maximum voltage value of all channels. This control method lacks flexibility. Similarly, undervoltage detection also has similar problems. Furthermore, the minimum operating current of the current constant current drive system is usually set at more than 100mA. For lamps with a demand current of less than 100mA, the system usually uses parallel resistors to shunt part of the current, which not only causes energy waste, but also increases the heat generation of the lamp board. Summary of the invention

[0004] The purpose of the present invention is to provide a constant current control circuit for vehicle lights and a vehicle controller. By designing a special anti-reverse control circuit for high-power drive loads, and accurately diagnosing over-voltage and under-voltage for each constant current channel, and controlling the current value of the constant current channel by adjusting the PWM duty cycle, the technical problems of failure of traditional anti-reverse protection function, lack of refined diagnosis of existing constant current control methods, and energy waste are solved.

[0005] In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

[0006] The present invention provides a constant current control circuit for a vehicle lamp, which comprises: a power supply module, an anti-reverse filtering module, a boost module, a control module and a constant current module;

[0007] The power supply module is respectively connected to the anti-reverse filtering module, the control module and the constant current module, and is used to supply power to the anti-reverse filtering module, the control module and the constant current module;

[0008] The anti-reverse filtering module includes a plurality of anti-reverse filtering units, each of which includes an input protection unit, an anti-reverse control chip, a power switch tube and an output filter unit. The input end of the input protection unit is connected to the power module, the output end is connected to the input end of the power switch tube, the output end of the power switch tube is connected to the input end of the output filter unit, the control end of the power switch tube is connected to the control pin of the anti-reverse control chip, and the output end of the output filter unit is connected to the input end of the boost module;

[0009] The output end of the boost module is connected to the input end of the constant current module to provide the power supply voltage required by the constant current module;

[0010] The output end of the constant current module is connected to the load, and is used to perform constant current control and fault diagnosis according to the driving characteristics of different loads;

[0011] The control module is connected to the boost module and the constant current module respectively, and is used to control the boost module to achieve stable boosting, and control the constant current module to stably drive the load.

[0012] In one embodiment of the present invention, the anti-reverse filtering module includes a first anti-reverse filtering unit and a second anti-reverse filtering unit;

[0013] The input end of the first anti-reverse filtering unit is connected to the first output end of the power module, and the output end is connected to the first input end of the boost module;

[0014] The input end of the second anti-reverse filtering unit is connected to the second output end of the power module, and the output end is connected to the second input end of the boost module;

[0015] The first anti-reverse filtering unit and the second anti-reverse filtering unit are independent of each other and are respectively used to filter the two independent power supply systems of the power module and prevent the power supply from being reversed.

[0016] In one embodiment of the present invention, the first anti-reverse filtering unit includes a first input protection unit, a first anti-reverse control chip, a first power switch tube and a first output filtering unit;

[0017] The input end of the first input protection unit is connected to the first output end of the power module, and the output end is connected to the input end of the first power switch tube;

[0018] The output end of the first power switch tube is connected to the input end of the first output filter unit, and the control end is connected to the control pin of the first anti-reverse control chip;

[0019] The output end of the first output filter unit is connected to the first input end of the boost module as the output end of the first anti-reverse filtering unit.

[0020] In one embodiment of the present invention, the first input protection unit includes a transient voltage suppression diode, a first capacitor and a second capacitor;

[0021] The first end of the transient voltage suppression diode, the first end of the first capacitor and the first end of the second capacitor are connected to the first output end of the power module;

[0022] The second end of the transient voltage suppression diode, the second end of the first capacitor and the second end of the second capacitor are connected to the ground.

[0023] In one embodiment of the present invention, the first output filter unit includes a fourth capacitor, a fifth capacitor, a filter inductor, a sixth capacitor, a seventh capacitor and an eighth capacitor;

[0024] The first end of the fourth capacitor, the first end of the fifth capacitor and the first end of the filter inductor are connected to the output end of the first power switch tube;

[0025] The first end of the sixth capacitor, the first end of the seventh capacitor, the first end of the eighth capacitor and the second end of the filter inductor are connected to the first input end of the boost module as the output end of the first anti-reverse filtering unit;

[0026] The second end of the fourth capacitor, the second end of the fifth capacitor, the second end of the sixth capacitor, the second end of the seventh capacitor and the second end of the eighth capacitor are connected to the ground.

[0027] In one embodiment of the present invention, the constant current module includes a BUCK control chip and a plurality of constant current channel units, the input end of each constant current channel unit is connected to the corresponding channel output pin of the BUCK control chip, and the output end is connected to the corresponding load.

[0028] In one embodiment of the present invention, the constant current module includes a first constant current channel unit, a second constant current channel unit and a third constant current channel unit;

[0029] The input end of the first constant current channel unit is connected to the first channel output pin of the BUCK control chip, and the output end is connected to the first load;

[0030] The input end of the second constant current channel unit is connected to the second channel output pin of the BUCK control chip, and the output end is connected to the second load;

[0031] The input end of the third constant current channel unit is connected to the third channel output pin of the BUCK control chip, and the output end is connected to the third load;

[0032] The first constant current channel unit, the second constant current channel unit and the third constant current channel unit are independent of each other and are respectively used to output a constant current to drive a corresponding load.

[0033] In one embodiment of the present invention, the first constant current channel unit includes a bootstrap resistor, a bootstrap capacitor, an energy storage inductor, a first bias resistor and a second bias resistor;

[0034] The bootstrap resistor and the bootstrap capacitor are connected in series and connected between the BOOT pin and the SW pin of the corresponding channel of the BUCK control chip;

[0035] The first end of the energy storage inductor is connected to the SW pin, and the second end is connected to the first end of the first bias resistor;

[0036] The second end of the first bias resistor and the first end of the second bias resistor are connected to the first load as output ends of the first constant current channel unit;

[0037] The second end of the second bias resistor is connected to the ground.

[0038] In one embodiment of the present invention, the first constant current channel unit further includes a first collection resistor and a second collection resistor, which are used to collect the output current of the first constant current channel unit;

[0039] A first end of the first acquisition resistor is connected to a first voltage acquisition pin of a channel corresponding to the BUCK control chip, and a second end of the first acquisition resistor is connected to a first end of the first bias resistor;

[0040] The first end of the second acquisition resistor is connected to the second voltage acquisition pin of the corresponding channel of the BUCK control chip, and the second end is connected to the second end of the first bias resistor.

[0041] Based on the same inventive concept, another embodiment of the present invention further provides a vehicle light controller, which includes the vehicle light constant current control circuit as described in any of the above embodiments.

[0042] As described above, the present invention provides a constant current control circuit for vehicle lights, comprising a power supply module, an anti-reverse filtering module, a boost module, a control module and a constant current module; the power supply module is respectively connected to the anti-reverse filtering module, the control module and the constant current module, and is used to supply power to the anti-reverse filtering module, the control module and the constant current module; the anti-reverse filtering module comprises a plurality of anti-reverse filtering units, each of which comprises an input protection unit, an anti-reverse control chip, a power switch tube and an output filter unit, the input end of the input protection unit is connected to the power supply module, the output end is connected to the input end of the power switch tube, and the power The output end of the switch tube is connected to the input end of the output filter unit, the control end of the power switch tube is connected to the control pin of the anti-reverse control chip, and the output end of the output filter unit is connected to the input end of the boost module; the output end of the boost module is connected to the input end of the constant current module to provide the power supply voltage required by the constant current module; the output end of the constant current module is connected to the load to perform constant current control and fault diagnosis according to the driving characteristics of different loads; the control module is respectively connected to the boost module and the constant current module to control the boost module to achieve stable boosting, and control the constant current module to stably drive the load. The vehicle lamp constant current control circuit utilizes the output voltage real-time detection function of the BUCK control chip. The control module MCU reads the actual output voltage detection value of the BUCK control chip through SPI communication, and compares it with the corresponding channel voltage threshold preset in the parameter layer. If the actual output voltage of the channel is greater than the maximum voltage value preset in the corresponding channel of the parameter layer, the channel output is immediately closed and an overvoltage fault is reported. If the actual output voltage of the channel is less than the minimum voltage value preset in the corresponding channel of the parameter layer, the channel output is immediately closed and an undervoltage fault is reported. By accurately diagnosing the actual required voltage of each channel and closing the abnormal channel separately in time, the self-system, lamps and surrounding electrical components are effectively protected.

[0043] In view of the requirements of driving high-power devices, a special anti-reverse control circuit is designed with anti-reverse polarity. Even if the positive and negative poles of the control module are reversed, the circuit can be immediately cut off to start the protection function to avoid damage to the control module. In addition, the MCU and the BOOST control chip and the BUCK control chip use two-wire communication, namely SPI serial communication and hard-wire communication. When the MCU detects that the SPI communication with the BOOST control chip or the BUCK control chip is abnormal, it can perform simple communication through the hard wire, start the limp home mode, and force the low beam and position lights to light up to ensure necessary safety lighting. At the same time, an independent dual power supply is used for power supply. If there is a power failure in any power supply, the other power supply can still maintain normal operation. When the light power exceeds the power limit of a single power supply, it will be derated in sequence according to the importance level of the light to ensure the normal operation of the headlights and safe driving. Furthermore, the constant current channel current can be flexibly controlled in two ways. If the constant current channel current value is required to be greater than or equal to 100mA, it can be directly set through the corresponding register of the BUCK control chip. However, if the constant current channel current value is required to be less than 100mA, it can be controlled by PWM duty cycle, and the setting of the constant current channel current is not restricted.

[0044] The constant current control circuit of the headlight can also realize the fault detection of the running water dynamic lamp, such as the running water turn signal lamp, by detecting the PWM value of each pixel of the running water lamp inside the headlight, when the duty cycle value of all pixels of the running water lamp reaches 100%, a certain delay time is set to ensure that the BUCK control chip has read the channel voltage value after the duty cycle value of all pixels of the running water lamp reaches 100% to the corresponding register, and then the MCU reads the channel voltage register value and compares it with the preset voltage threshold to determine whether a fault occurs. Of course, any product implementing the present invention does not necessarily need to achieve all the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0046] Figure 1 This is a structural block diagram of a vehicle light constant current control circuit provided by an exemplary embodiment of the present application.

[0047] Figure 2 A circuit diagram of an anti-reverse filtering module provided by an exemplary embodiment of the present application.

[0048] Figure 3 A circuit diagram of a constant current module provided by an exemplary embodiment of the present application.

[0049] Figure 4 A schematic diagram of a current regulation curve of a first constant current channel provided by an exemplary embodiment of the present application.

[0050] The reference numerals are as follows:

[0051] 100 Power Module

[0052] 200 Anti-reverse filtering module

[0053] 210 First anti-reverse filter unit

[0054] 211 First input protection unit

[0055] 212 first output filter unit

[0056] 220 Second anti-reverse filter unit

[0057] 221 Second input protection unit

[0058] 222 Second output filter unit

[0059] 300 Boost Module

[0060] 400 Control Module

[0061] 500 Constant Current Module

[0062] 510 First constant current channel unit

[0063] 520 Second constant current channel unit

[0064] 530 The third constant current channel unit

[0065] 600 Load DETAILED DESCRIPTION

[0066] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0067] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0068] In the following description, numerous details are discussed to provide a more thorough explanation of the embodiments of the present invention. However, it is obvious to those skilled in the art that the embodiments of the present invention can be implemented without these specific details. In other embodiments, well-known structures and devices are shown in the form of block diagrams rather than in detail to avoid making the embodiments of the present invention difficult to understand.

[0069] In order to solve the technical problems of failure of traditional anti-reverse protection function, lack of refined diagnosis of existing constant current control methods and energy waste, the present invention provides a constant current control circuit for vehicle lights, by designing a special anti-reverse control circuit for high-power drive loads, and accurately diagnosing over-voltage and under-voltage for each constant current channel, and controlling the current value of the constant current channel by adjusting the PWM duty cycle.

[0070] See also Figure 1 As shown, in an exemplary embodiment of the present application, the headlight constant current control circuit includes a power module 100, an anti-reverse filtering module 200, a boost module 300, a control module 400 and a constant current module 500; the power module 100 is respectively connected to the anti-reverse filtering module 200, the control module 400 and the constant current module 500, and is used to supply power to the anti-reverse filtering module 200, the control module 400 and the constant current module 500; the anti-reverse filtering module 200 includes a plurality of anti-reverse filtering units, each of which includes an input protection unit, an anti-reverse control chip, a power switch tube and an output filter unit, the input end of the input protection unit is connected to the power module, and the output end is connected to the input end of the power switch tube. The output end of the power switch tube is connected to the input end of the output filter unit, the control end of the power switch tube is connected to the control pin of the anti-reverse control chip, and the output end of the output filter unit is connected to the input end of the boost module; the output end of the boost module 300 is connected to the input end of the constant current module 500, for providing the power supply voltage required by the constant current module 500; the output end of the constant current module 500 is connected to the load 600, for constant current control and fault diagnosis according to the driving characteristics of different loads 600; the control module 400 is respectively connected to the boost module 300 and the constant current module 500, for controlling the boost module 300 to achieve stable boosting, and controlling the constant current module 500 to stably drive the load.

[0071] It should be noted that, in the present embodiment, the control module 400 is a microcontroller unit (MCU), and the power switch tube is an N-type field effect transistor, i.e., an NMOS tube. Of course, in other embodiments, the power switch tube may also be an IGBT tube. The power module 100 is an SDB power module, which includes two independent power supply systems KL15 and KL56, which are used to provide 12V power to the anti-reverse filtering module 200. It is worth noting that the power module 100 is also used to provide 5V power to the control module 400 and the constant current module 500 by stepping down the voltage through a low dropout linear regulator (LDO) circuit. It is worth noting that in the present embodiment, since the power module 100 includes two independent power supply systems, the anti-reverse filtering unit is set to two. Of course, in other embodiments, it can be customized according to the actual application scenario and requirements.

[0072] In an exemplary embodiment of the present application, see Figure 1 and Figure 2 As shown, the anti-backward filtering module 200 includes a first anti-backward filtering unit 210 and a second anti-backward filtering unit 220; the input end of the first anti-backward filtering unit 210 is connected to the first output end of the power module 100, and the output end is connected to the first input end of the boost module 300; the input end of the second anti-backward filtering unit 220 is connected to the second output end of the power module 100, and the output end is connected to the second input end of the boost module 300; the first anti-backward filtering unit 210 and the second anti-backward filtering unit 220 are independent of each other, and are respectively used to filter the two independent power supply systems of the power module 100 and prevent power reverse connection.

[0073] In an exemplary embodiment of the present application, see Figure 2 As shown, the first anti-reverse filtering unit 210 includes a first input protection unit 211, a first anti-reverse control chip U1, a first power switch tube Q1 and a first output filtering unit 212; the input end of the first input protection unit 211 is connected to the first output end of the power module 100, and the output end is connected to the input end of the first power switch tube Q1; the output end of the first power switch tube Q1 is connected to the input end of the first output filtering unit 212, and the control end is connected to the control pin GATE of the first anti-reverse control chip U1; the output end of the first output filtering unit 212 is connected to the first input end of the boost module 300 as the output end of the first anti-reverse filtering unit 210.

[0074] In an exemplary embodiment of the present application, see Figure 2As shown, the first input protection unit 210 includes a transient voltage suppression diode D1, a first capacitor C1 and a second capacitor C2; the first end of the transient voltage suppression diode D1, the first end of the first capacitor C1 and the first end of the second capacitor C2 are connected to the first output end of the power module 100; the second end of the transient voltage suppression diode D1, the second end of the first capacitor C1 and the second end of the second capacitor C2 are connected to the ground GND.

[0075] In an exemplary embodiment of the present application, see Figure 2 As shown, the first output filter unit 210 includes a fourth capacitor C4, a fifth capacitor C5, a filter inductor L1, a sixth capacitor C6, a seventh capacitor C7 and an eighth capacitor C8; the first end of the fourth capacitor C4, the first end of the fifth capacitor C5 and the first end of the filter inductor L1 are connected to the output end of the first power switch tube Q1; the first end of the sixth capacitor C6, the first end of the seventh capacitor C7, the first end of the eighth capacitor C8 and the second end of the filter inductor L1 are connected to the first input end of the boost module 300 as the output end of the first anti-reverse filter unit 210; the second end of the fourth capacitor C4, the second end of the fifth capacitor C5, the second end of the sixth capacitor C6, the second end of the seventh capacitor C7 and the second end of the eighth capacitor C8 are connected to the ground GND.

[0076] It should be noted that the first output filter unit is a π-type low-pass filter, which is suitable for applications with large load currents and is used to suppress ripple noise at the output end. In addition, the circuit structure and working principle of the second anti-reverse filtering unit 220 are the same as those of the first anti-reverse filtering unit 210, which will not be repeated here.

[0077] In an exemplary embodiment of the present application, see Figure 1 and Figure 3 As shown, the constant current module 500 includes a BUCK control chip U3 and a plurality of constant current channel units, the input end of each constant current channel unit is connected to the corresponding channel output pin of the BUCK control chip U3, and the output end is connected to the corresponding load 600.

[0078] In an exemplary embodiment of the present application, see Figure 3As shown, the constant current module 500 includes a first constant current channel unit 510, a second constant current channel unit 520 and a third constant current channel unit 530; the input end of the first constant current channel unit 510 is connected to the first channel output pin of the BUCK control chip U3, and the output end is connected to the first load; the input end of the second constant current channel unit 520 is connected to the second channel output pin of the BUCK control chip U3, and the output end is connected to the second load; the input end of the third constant current channel unit 530 is connected to the third channel output pin of the BUCK control chip U3, and the output end is connected to the third load; the first constant current channel unit 510, the second constant current channel unit 520 and the third constant current channel unit 530 are independent of each other, and are respectively used to output constant current to drive corresponding loads.

[0079] In an exemplary embodiment of the present application, see Figure 3 As shown, the first constant current channel unit 510 includes a bootstrap resistor R15, a bootstrap capacitor C23, an energy storage inductor L3, a first bias resistor R16 and a second bias resistor R17; the bootstrap resistor R15 and the bootstrap capacitor C23 are connected in series and connected between the BOOT pin and the SW pin of the corresponding channel of the BUCK control chip U3; the first end of the energy storage inductor L3 is connected to the SW pin, and the second end is connected to the first end of the first bias resistor R16; the second end of the first bias resistor R16 and the first end of the second bias resistor R17 are connected to the first load as the output end of the first constant current channel unit 510; the second end of the second bias resistor R17 is connected to the ground GND.

[0080] In an exemplary embodiment of the present application, see Figure 3 As shown, the first constant current channel unit 510 also includes a first acquisition resistor R14 and a second acquisition resistor R13, which are used to collect the output current of the first constant current channel unit 510; the first end of the first acquisition resistor R14 is connected to the first voltage acquisition pin SNSP1 of the channel corresponding to the BUCK control chip U3, and the second end is connected to the first end of the first bias resistor R16; the first end of the second acquisition resistor R13 is connected to the second voltage acquisition SNSN1 pin of the channel corresponding to the BUCK control chip U3, and the second end is connected to the second end of the first bias resistor R16.

[0081] It should be noted that the circuit structure and working principle of the second constant current channel unit 520 and the third constant current channel unit 530 are the same as those of the first constant current channel unit 510, which will not be repeated here. It is worth noting that the first load, the second load and the third load are different lamps configured on the vehicle, such as low beam lights, position lights, high beam lights, turn signals, etc.

[0082] Next, the working principle of the headlight constant current control circuit will be described in detail:

[0083] See also Figure 2 As shown, the anti-reverse filtering module 200 is composed of two independent anti-reverse filtering units, which filter the KL15 and KL56 power supplies and prevent the power supply from being reversed. Taking the first anti-reverse filtering unit 210 as an example, when the KL15 end is correctly connected to the power supply and the GND end is grounded, the anti-reverse control chip U1 controls the first power switch tube Q1 to be turned on, and the current can flow smoothly at this time. When the power supply and ground are reversed due to misoperation or other reasons, the anti-reverse control chip U1 can immediately turn off the first power switch tube Q1, thereby preventing the current from being reversed and damaging the controller and external devices. It should be noted that the working principle of the KL56 input circuit is consistent with the KL15 input circuit, which will not be repeated here.

[0084] See also Figure 3 As shown in FIG. 1 , the BUCK constant current module is powered by the BOOST step-up module. The MCU control module writes the current value that each BUCK channel (such as channel 1: SW1; channel 2: SW2; channel 3: SW3, etc.) needs to output into the corresponding register through SPI communication. The BUCK control chip U3 reads the register value storing the output current value and controls the on / off of SW1 / SW2 / SW3 through the internal MOS tube to maintain the constant output current value. For example, when the BUCK control chip U3 controls SW1 to be turned on through the internal MOS tube, the energy storage inductor L3 starts to charge, and the current flowing through the energy storage inductor L3 gradually increases. The BUCK control chip U3 The chip U3 reads the actual current value of channel SW1 through the voltage acquisition pins SNSN1 and SNSP1. When the read current value reaches the current value set in the register ± the set over-limit value, the BUCK control chip U3 immediately cuts off the power supply of the SW1 channel through the internal MOS tube. At this time, the energy storage inductor L3 has the characteristic that the current cannot change suddenly, that is, when SW1 cuts off the power supply, the energy storage inductor L3 will maintain the current value before the cut-off moment and discharge slowly. During the discharge process of the energy storage inductor L3, the BUCK control chip U3 reads the actual current value of channel SW1 through the voltage acquisition pins SNSN1 and SNSP1. When the read current value is less than the current value set in the register I SW1 Subtract the set lower limit I 2 , the BUCK control chip U3 immediately controls the internal MOS tube to turn on the SW1 channel. At the moment of turn-on, the energy storage inductor L3 will maintain the current value before the turn-on moment and slowly start to charge. The current of channel SW1 slowly starts to increase. At the same time, when the voltage acquisition pins SNSN1 and SNSP1 read the actual current value of channel SW1 and reach the register set current value I sW1 Add the set limit value I 1When the BUCK control chip U3 immediately cuts off the power supply of SW1 channel through the internal MOS tube, and repeats this process to basically maintain the output channel current value unchanged. For current value changes, please refer to Figure 4 shown.

[0085] It should be noted that the constant current module 500 can use the real-time output voltage detection function of the BUCK control chip U3 to perform over-voltage and under-voltage fault diagnosis on the output voltage of each constant current channel. Specifically, the BUCK control chip U3 reads the actual output voltage value of the SW1 channel through the pin SNSN1, and stores the value in the specified register, and the register value is updated according to a certain period. The control module 400 reads the register value through SPI communication and performs fault judgment according to the preset maximum voltage value and minimum voltage value of the channel. When the actual voltage value of the channel is greater than the preset maximum voltage value, the control module 400 will immediately feedback the overvoltage fault to the instrument to remind the driver that the channel has an overvoltage fault, and close the channel, thereby protecting the self-module and external electrical appliances from damage. Similarly, when the actual voltage value of the channel is less than the preset minimum voltage value, the control module 400 will immediately feedback the undervoltage fault to the instrument to remind the driver that the channel has an undervoltage fault, and close the channel, thereby protecting the self-module and external electrical appliances from damage.

[0086] Since the channel current setting value of the BUCK control chip U3 is required to be greater than 100mA, and in fact some lamps require a current less than 100mA, in order to meet the current requirements of these lamps, the control module 400 can be achieved by adjusting the PWM duty cycle. For example, for the constant current channel SW1, the design required current is 66mA, the current setting register of the channel SW1 can be set to 100mA, and then the MCU will calculate the corresponding PWM duty cycle of 66%, and then write the duty cycle value to the corresponding duty cycle register through SPI communication, thereby achieving a constant current output less than 100mA.

[0087] In addition, the constant current module 500 can not only perform over-voltage and under-voltage detection on the always-on lamps, but also realize fault detection on the running lamps. Specifically, the BUCK control chip U3 will periodically write the actual output voltage of each channel into the corresponding register, and the control module 400 will continuously change the register value of the matrix chip to control the voltage duty cycle of each pixel to realize the running light effect. When the voltage duty cycle register values ​​corresponding to all pixels of the running light reach 100%, the control module 400 will wait for an interval equal to the channel voltage reading cycle of the BUCK control chip U3, and then read the register value of the voltage value stored in the corresponding channel of the BUCK control chip U3, and compare the value with the preset voltage threshold. According to the comparison result, the MCU will determine whether the running light is faulty, thereby realizing the fault diagnosis of the running light.

[0088] In addition, the control module 400 in the vehicle light constant current control circuit and the BUCK control chip U3 use a dual communication mode of SPI serial communication + hard-wire communication. When the control module 400 detects a BUCK control chip U3 failure or an SPI communication failure, the low beam channel output of the BUCK control chip U3 can be forcibly controlled through hard-wire communication to ensure basic safety lighting.

[0089] Furthermore, the constant current control circuit of the vehicle lights adopts two independent power supply systems KL15 and KL56. When one of the power supply systems is abnormal, the other can maintain the normal operation of the system. If the total power of the lights turned on at this time exceeds the limit of the single power supply, the control module 400 will perform partial derating according to the priority of the light function to ensure the normal function of the low beam and turn signal. For example, when the power supply of KL15 is abnormal and only KL56 is left for power supply, if the driver turns on the position light, low beam, turn signal and high beam at the same time, since the total power of these lights exceeds the limit of the single power supply, the control module 400 will first ensure the full power output of the low beam and turn signal, and then derating the high beam, that is, reduce the output current of the corresponding channel until the high beam is turned off. If the total power still exceeds the limit after the high beam is turned off, the control module 400 will derating the position light again until the total power is less than or equal to the limit of the single power supply. While derating, the control module 400 will also send this fault signal to the instrument to prompt the driver to repair the fault.

[0090] Based on the same inventive concept, another embodiment of the present invention further provides a vehicle light controller, the vehicle light controller comprising the vehicle light constant current control circuit described in any of the above embodiments. Since the vehicle light controller provided in this embodiment and the vehicle light constant current control circuit provided in any of the above embodiments belong to the same inventive concept, they at least have the same beneficial effects as the above embodiments, and are not described one by one here.

[0091] In summary, the constant current control circuit of the headlights performs separate and accurate diagnosis for the voltage required for each constant current channel to drive the lamps and the corresponding overvoltage and undervoltage conditions. When a fault occurs, the circuit can be cut off more quickly, thereby providing more timely protection for the controller itself, the lamps and surrounding electrical appliances. For high-power drive loads, the circuit is designed with a special anti-reverse control circuit. When the power supply is reversed, the circuit can be cut off immediately to protect the constant current control circuit of the headlights from being burned out, and also to protect the entire vehicle circuit to a certain extent. In addition, the control module 400 and the BOOST control chip and the BUCK control chip use two-wire communication, namely SPI serial communication and hard-wire communication. When the SPI serial communication fails, the control module 400 can communicate through the hard wire and immediately start the limp home mode to ensure the necessary safety lighting. In addition, the circuit uses two independent power supply systems. As long as any one of the systems is powered normally, the circuit can work normally. Therefore, the circuit has stronger fault tolerance and higher stability to faults. Furthermore, the constant current channel current is flexibly controlled in a variety of ways, and can be precisely controlled according to the needs of the driving load, saving electric energy and reducing the heating of the lamp board, which is more conducive to extending the service life of the lamp. For the fault detection of the running water lamp, the circuit adopts a double detection confirmation method for diagnosis. First, the MCU confirms that the duty cycle of all pixels of the matrix chip controlling the running water lamp reaches 100%. This is the first confirmation. After confirming that the duty cycle of all pixels reaches 100%, the MCU does not immediately read the voltage value of the corresponding channel of the BUCK control chip U3, but delays a cycle of the BUCK control chip detecting the constant current channel voltage value to ensure that the BUCK control chip U3 has stored the voltage value of all pixels when the duty cycle is 100% in the corresponding register. This is the second confirmation. At this time, the control module 400 reads the corresponding register value of the BUCK control chip U3 and compares the voltage value to determine whether the running water lamp is faulty. Compared with the prior art, the circuit is more accurate in fault diagnosis of the running water lamp, fundamentally avoiding the risk of misjudgment.

[0092] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A constant current control circuit for a vehicle light, characterized in that: include: Power module, anti-reverse filtering module, boost module, control module and constant current module; The power supply module is respectively connected to the anti-reverse filtering module, the control module and the constant current module, and is used to supply power to the anti-reverse filtering module, the control module and the constant current module; The anti-reverse filtering module includes a plurality of anti-reverse filtering units, each of which includes an input protection unit, an anti-reverse control chip, a power switch tube and an output filter unit. The input end of the input protection unit is connected to the power module, the output end is connected to the input end of the power switch tube, the output end of the power switch tube is connected to the input end of the output filter unit, the control end of the power switch tube is connected to the control pin of the anti-reverse control chip, and the output end of the output filter unit is connected to the input end of the boost module; The output end of the boost module is connected to the input end of the constant current module to provide the power supply voltage required by the constant current module; The output end of the constant current module is connected to the load, and is used to perform constant current control and fault diagnosis according to the driving characteristics of different loads; The control module is connected to the boost module and the constant current module respectively, and is used to control the boost module to achieve stable boosting, and control the constant current module to stably drive the load.

2. The vehicle light constant current control circuit according to claim 1, characterized in that: The anti-reverse filtering module includes a first anti-reverse filtering unit and a second anti-reverse filtering unit; The input end of the first anti-reverse filtering unit is connected to the first output end of the power module, and the output end is connected to the first input end of the boost module; The input end of the second anti-reverse filtering unit is connected to the second output end of the power module, and the output end is connected to the second input end of the boost module; The first anti-reverse filtering unit and the second anti-reverse filtering unit are independent of each other and are respectively used to filter the two independent power supply systems of the power module and prevent the power supply from being reversed.

3. The vehicle light constant current control circuit according to claim 2, characterized in that: The first anti-reverse filtering unit includes a first input protection unit, a first anti-reverse control chip, a first power switch tube and a first output filtering unit; The input end of the first input protection unit is connected to the first output end of the power module, and the output end is connected to the input end of the first power switch tube; The output end of the first power switch tube is connected to the input end of the first output filter unit, and the control end is connected to the control pin of the first anti-reverse control chip; The output end of the first output filter unit is connected to the first input end of the boost module as the output end of the first anti-reverse filtering unit.

4. The vehicle light constant current control circuit according to claim 3, characterized in that: The first input protection unit includes a transient voltage suppression diode, a first capacitor and a second capacitor; The first end of the transient voltage suppression diode, the first end of the first capacitor and the first end of the second capacitor are connected to the first output end of the power module; The second end of the transient voltage suppression diode, the second end of the first capacitor and the second end of the second capacitor are connected to the ground.

5. The vehicle light constant current control circuit according to claim 3, characterized in that: The first output filter unit includes a fourth capacitor, a fifth capacitor, a filter inductor, a sixth capacitor, a seventh capacitor and an eighth capacitor; The first end of the fourth capacitor, the first end of the fifth capacitor and the first end of the filter inductor are connected to the output end of the first power switch tube; The first end of the sixth capacitor, the first end of the seventh capacitor, the first end of the eighth capacitor and the second end of the filter inductor are connected to the first input end of the boost module as the output end of the first anti-reverse filtering unit; The second end of the fourth capacitor, the second end of the fifth capacitor, the second end of the sixth capacitor, the second end of the seventh capacitor and the second end of the eighth capacitor are connected to the ground.

6. The vehicle light constant current control circuit according to claim 1, characterized in that: The constant current module includes a BUCK control chip and a plurality of constant current channel units. The input end of each constant current channel unit is connected to the corresponding channel output pin of the BUCK control chip, and the output end is connected to the corresponding load.

7. The vehicle light constant current control circuit according to claim 6, characterized in that: The constant current module includes a first constant current channel unit, a second constant current channel unit and a third constant current channel unit; The input end of the first constant current channel unit is connected to the first channel output pin of the BUCK control chip, and the output end is connected to the first load; The input end of the second constant current channel unit is connected to the second channel output pin of the BUCK control chip, and the output end is connected to the second load; The input end of the third constant current channel unit is connected to the third channel output pin of the BUCK control chip, and the output end is connected to the third load; The first constant current channel unit, the second constant current channel unit and the third constant current channel unit are independent of each other and are respectively used to output a constant current to drive a corresponding load.

8. The vehicle light constant current control circuit according to claim 7, characterized in that: The first constant current channel unit includes a bootstrap resistor, a bootstrap capacitor, an energy storage inductor, a first bias resistor and a second bias resistor; The bootstrap resistor and the bootstrap capacitor are connected in series and connected between the BOOT pin and the SW pin of the corresponding channel of the BUCK control chip; The first end of the energy storage inductor is connected to the SW pin, and the second end is connected to the first end of the first bias resistor; The second end of the first bias resistor and the first end of the second bias resistor are connected to the first load as output ends of the first constant current channel unit; The second end of the second bias resistor is connected to the ground.

9. The vehicle light constant current control circuit according to claim 8, characterized in that: The first constant current channel unit further includes a first collection resistor and a second collection resistor, which are used to collect the output current of the first constant current channel unit; A first end of the first acquisition resistor is connected to a first voltage acquisition pin of a channel corresponding to the BUCK control chip, and a second end of the first acquisition resistor is connected to a first end of the first bias resistor; The first end of the second acquisition resistor is connected to the second voltage acquisition pin of the corresponding channel of the BUCK control chip, and the second end is connected to the second end of the first bias resistor.

10. A vehicle light controller, characterized in that: The vehicle light controller comprises a vehicle light constant current control circuit as described in any one of claims 1 to 9 above.

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