Method for automatically adjusting dummy load of LED car lights and dummy load system of LED car lights

Abstract

A method for automatically adjusting the dummy load of an LED car light and a dummy load system for an LED car light. The method for automatically adjusting the dummy load of an LED car light comprises: before the LED car light works, the controller determines the working position of the dummy load circuit when the LED car light is started according to the given dummy load configuration current I_set of the LED car light, and adjusts the dummy load circuit to the working position; after the LED car light works, the controller obtains the power current value I_led consumed by the LED car light when working in real time, and calculates the power current value I_dummy consumed by the required dummy load circuit according to I_set and I_led: I_dummy=I_set‑I_led; the controller updates the working position of the dummy load circuit according to I_dummy. The present invention can automatically adjust the current consumption of the dummy load circuit to adapt to different vehicle models and different LED car light working conditions.

Description

Technical Field

[0001] The invention relates to a control technology for automobile lamps. Background Art

[0002] The LED headlight controller is connected to the body control module (BCM). The BCM has a current diagnosis function. Its current detection circuit monitors the current consumed by the LED headlight controller in real time. When the current is less than the preset current threshold, the BCM will consider that the LED headlight controller is in a fault state and give a fault alarm.

[0003] LED headlights (i.e., LED headlights of cars) have unstable output current during the startup phase, and the output power of LED running turn signals is insufficient when they are started. All of the above situations will cause the BCM current detection circuit to be unable to detect effective drive current, thus causing a fault error. In order to prevent this phenomenon, a dummy load circuit is introduced. When the drive current is small, the dummy load is used to increase the drive current, thereby ensuring the normal operation of the LED headlight control circuit (LED headlight controller) and not causing BCM to falsely report a fault.

[0004] Please refer to Figure 1 . The current dummy load design is mainly to connect a high-precision resistor R in series in the input circuit of the LED headlight 8a, amplify the voltage difference across the resistor R through an amplifier circuit, and finally output a control signal through a comparator to control the switch of the dummy load circuit 1a (R_dummy is the dummy load resistor). This design uses a pure hardware circuit to implement the functional control of the dummy load circuit, which is costly, and the dummy load consumes a fixed power, which cannot be adapted to different vehicle models, because different vehicle models have different current standards for load consumption, and the corresponding dummy load consumption will also be different. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for automatically adjusting the dummy load of LED car lights and an LED car light dummy load system, which can automatically adjust the current consumption of the dummy load circuit to adapt to different vehicle models and different LED car light working conditions, and has low implementation cost.

[0006] A method for automatically adjusting a dummy load of an LED vehicle lamp according to an embodiment of the present invention includes:

[0007] Before the LED lamp works, the controller determines the working position of the dummy load circuit when the LED lamp is started according to the given dummy load configuration current I_set of the LED lamp, and adjusts the dummy load circuit to the working position; wherein the dummy load circuit has multiple working positions, and the consumption current of the dummy load circuit is different at different working positions;

[0008] After the LED headlight is working, the controller obtains the power current value I_led consumed by the LED headlight in real time, and calculates the power current value I_dummy consumed by the required dummy load circuit according to I_set and I_led: I_dummy=I_set-I_led;

[0009] The controller updates the working gear of the dummy load circuit according to I_dummy.

[0010] According to an embodiment of the present invention, a LED car light dummy load system includes a dummy load circuit, an LED driving circuit and a controller; the power input end of the dummy load circuit and the power input end of the LED driving circuit are respectively connected to the power supply of the LED car light control circuit, the output end of the LED driving circuit is connected to the voltage input end of the LED car light, and the first control output end of the controller is connected to the control input end of the LED driving circuit. The LED car light dummy load system also includes an LED voltage acquisition circuit and a power supply voltage acquisition circuit; the output end of the LED voltage acquisition circuit and the output end of the power supply voltage acquisition circuit are respectively connected to the first input end and the second input end of the controller; the LED voltage acquisition circuit is used to acquire the output voltage V_out of the LED car light, and the power supply voltage acquisition circuit is used to acquire the power supply of the power supply of the LED car light control circuit in real time. voltage V_bat; the dummy load circuit has multiple working gears, and the current consumption of the dummy load circuit is different in different working gears; the second control output end of the controller is connected to the control input end of the dummy load circuit, and the controller is used to determine the working gear that the dummy load circuit should be at when the LED light is started according to the given dummy load configuration current I_set of the LED light before the LED light works, and adjust the dummy load circuit to the working gear; after the LED light works, the power supply current value I_led consumed by the LED light when working is calculated in real time according to V_out and V_bat, and the power supply current value I_dummy consumed by the required dummy load circuit is calculated in real time according to I_set and I_led, and the working gear of the dummy load circuit is updated according to the calculated I_dummy, I_dummy=I_set-I_led.

[0011] The present invention has at least the following advantages:

[0012] 1. The dummy load circuit of the embodiment of the present invention has multiple working gears. The current consumption of the dummy load circuit is different in different working gears. Before the LED lamp is started, the controller can determine the working gear of the dummy load circuit when the LED lamp is started according to the obtained dummy load configuration current I_set of the LED lamp, and adjust the dummy load circuit to the working gear, which can adapt to different vehicle models;

[0013] 2. When the LED headlight is working, the controller calculates the power current consumed by the real-time dummy load circuit according to the power current value I_led consumed by the LED headlight, so as to accurately control the operation of the dummy load circuit to adapt to the current working condition of the LED headlight. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A functional block diagram of a conventional dummy load system for an LED headlight is shown.

[0015] Figure 2 A circuit principle block diagram of a dummy load system of an LED vehicle lamp according to an embodiment of the present invention is shown.

[0016] Figure 3 A circuit schematic diagram of a dummy load circuit according to an embodiment of the present invention is shown.

[0017] Figure 4 A circuit schematic diagram of a configuration resistor acquisition circuit according to an embodiment of the present invention is shown.

[0018] Figure 5 A schematic flow chart of a method for automatically adjusting a dummy load of an LED vehicle lamp according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0019] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] Please refer to Figures 2 to 4 The dummy load system of the LED vehicle lamp according to an embodiment of the present invention comprises a dummy load circuit 1, a configuration resistor acquisition circuit 2, an external configuration resistor R_set, an LED voltage acquisition circuit 3, a power supply voltage acquisition circuit 4, a controller 5 and an LED driving circuit 6.

[0021] The power input end of the dummy load circuit 1 and the power input end of the LED driving circuit 6 are respectively connected to the power supply 7 of the LED car light control circuit, the output end of the LED driving circuit 6 is connected to the voltage input end of the LED car light 8, and the first control output end of the controller 5 is connected to the control input end of the LED driving circuit 6. The output end of the LED voltage acquisition circuit 3 and the output end of the power supply voltage acquisition circuit 4 are respectively connected to the first input end and the second input end of the controller 5; the LED voltage acquisition circuit 3 is used to collect the output voltage V_out of the LED car light 8 in real time, and the power supply voltage acquisition circuit 4 is used to collect the power supply voltage V_bat of the power supply 7 of the LED car light control circuit in real time.

[0022] In this embodiment, the power supply 7 of the LED car light control circuit is a car battery, and the LED driving circuit 6 uses an LED driving chip.

[0023] The dummy load circuit 1 has multiple working gears, and the current consumption of the dummy load circuit is different at different working gears. In this embodiment, the dummy load circuit 1 includes multiple dummy load branches 11 connected in parallel with each other. The power input ends of the multiple dummy load branches 11 are respectively connected to the power supply 7 of the LED light control circuit; the second control output end of the controller 5 is respectively connected to the control input end of the multiple dummy load branches 11, and the controller 5 can control the on and off of each dummy load branch 11 to adjust the working gear of the dummy load circuit 1 by controlling the number of dummy load branches involved in the work. Further, each dummy load branch 11 includes a pull-up resistor, a grounding resistor, a switch current limiting resistor and a dummy load switch. One end of the pull-up resistor is connected to the power supply voltage V_bat of the power supply of the LED light control circuit, the other end of the pull-up resistor is connected to the first end of the dummy load switch, the second end of the dummy load switch is connected to one end of the grounding resistor, the other end of the grounding resistor is grounded, and the control end of the dummy load switch is connected to the second control output end of the controller 5 through the switch current limiting resistor.

[0024] In this embodiment, the dummy load switch is a PNP transistor, and the emitter, collector and base of the PNP transistor respectively constitute the first end, the second end and the control end of the dummy load switch. The controller 5 adopts an MCU, and uses the general input and output port (GPIO) of the MCU as the control output end of the controller to control the conduction and closing of the PNP transistor. Figure 3 In the example, the dummy load circuit 1 includes three dummy load branches 11, and the dummy load switches Q1, Q2 and Q3 of the three dummy load branches 11 are respectively connected to the three GPIO ports CTL1, CTL2 and CTL3 of the MCU5, and each GPIO port controls the switch of one dummy load branch. The consumption currents of multiple dummy load branches can be the same or different. By presetting the consumption current of each dummy load branch and allocating the control level corresponding to each working gear, the controller 5 can accurately control the working gear of the dummy load circuit.

[0025] In a specific implementation, when CTL1 outputs a low level, the first dummy load branch works and consumes 100mA of current; when CTL1 outputs a high level, the first dummy load branch does not consume current. When CTL2 outputs a low level, the second dummy load branch works and consumes 200mA of current; when CTL2 outputs a high level, the second dummy load branch does not consume current. When CTL3 outputs a low level, the third dummy load branch works and consumes 300mA of current; when CTL2 outputs a high level, the third dummy load branch does not consume current.

[0026] Assuming that in actual operation, the controller 5 calculates that the dummy load consumption is 450mA, the output of the controller 5 is controlled as follows: CTL1 outputs a high level, and CTL2 and CTL3 output a low level. At this time, the dummy load current consumption is 200mA+300mA=500mA, which is greater than 450mA and meets the requirement.

[0027] The current consumption of the dummy load will be affected by the power supply voltage V_bat, so it is best to have a certain margin when designing. For example, the rated current consumption of the dummy load branch corresponding to CTL1 is 100mA; the actual current consumption of the design is slightly greater than 100mA, which can ensure that a larger dummy load gear is obtained in the end.

[0028] The external configuration resistor R_set is pre-installed on the vehicle, one end of the external configuration resistor R_set is grounded, and is used to configure the dummy load configuration current I_set required by the LED vehicle lamp.

[0029] In this embodiment, the configuration resistor acquisition circuit 2 includes a power supply VDD, a resistor R0 and a resistor R1. The output end of the power supply VDD is connected to one end of the resistor R0, one end of the resistor R1 is connected to the other end of the resistor R0, and the other end of the resistor R1 is connected to the third input end of the controller 5 (specifically, the AD sampling end of the MCU); the common node between one end of the resistor R1 and the other end of the resistor R0 constitutes the input end of the configuration resistor acquisition circuit, and the other end of the resistor R1 constitutes the output end of the configuration resistor acquisition circuit.

[0030] The external configuration resistor R_set and the resistor R1 form a resistor divider circuit. For a certain vehicle model or product, the value of R_set is fixed. When the input end of the configuration resistor acquisition circuit 2 is connected to an external configuration resistor R_set of different resistance values ​​(the input end of the configuration resistor acquisition circuit 2 is connected to the other end of the external configuration resistor R_set), the controller 5 can configure different dummy load configuration currents I_set. Changes in vehicle models or product parameters cause R_set to change accordingly. Using the configuration resistor acquisition circuit 2, the controller 5 can easily calculate the resistance value of the product's external configuration resistor R_set and automatically configure different dummy load configuration currents I_set to adapt to changes in vehicle models. The resistance calculation formula of the external configuration resistor R_set is as follows:

[0031]

[0032] It is deduced that:

[0033]

[0034] in:

[0035] Resistor R0 is the pull-up resistor of the resistor divider circuit;

[0036] ADC is the AD code value read by the ADC module of the MCU;

[0037] ADC0 is the maximum value of the AD code (the AD code corresponding to VDD). The relationship between its value and the accuracy of the ADC module is: ADC0 = 2 n –1; for example, when the accuracy of the ADC module is 10 bits (that is, n=10), the corresponding ADC0 value is 1023, and the corresponding ADC0 value of 12 bits is 4095.

[0038] After calculating R_set, the controller 5 uses a table lookup method to obtain the dummy load configuration current I_set. Taking the dummy load circuit 1 having six working gears (in other embodiments, it is not limited to six working gears, and six working gears can meet most needs) as an example, a table storing the corresponding relationship between the resistance value of the external configuration resistor R_set and the dummy load configuration current I_set is as follows:

[0039] R_set / KΩ 1 2 3 4 5 6 I_set / mA 100 200 300 400 500 600

[0040] In order to meet the I_set current, when calculating the working gear of the dummy load circuit, if there is a remainder after the calculation of R_set, the working gear needs to be increased by 1 to ensure that the final dummy load circuit consumption current meets the I_set requirement. For example, assuming that the calculated resistance value of the external configuration resistor R_set is 2.03KΩ, then the corresponding dummy load configuration current I_set should be 300mA instead of 200mA.

[0041] Please refer to Figure 5 The method for automatically adjusting the dummy load of an LED vehicle lamp according to an embodiment of the present invention comprises:

[0042] Before the LED lamp 8 works, the controller 5 determines the working position of the dummy load circuit when the LED lamp is started according to the given dummy load configuration current I_set of the LED lamp 8, and adjusts the dummy load circuit 1 to the working position (making the dummy load branch corresponding to the working position in an open state to ensure that the dummy load circuit meets the current consumption in the shortest time after the LED lamp is started), so that the dummy load circuit works at the working position when the LED lamp is started; wherein the dummy load circuit has multiple working positions, and the consumption current of the dummy load circuit is different at different working positions;

[0043] After the LED lamp 8 is working, the controller obtains the power current value I_led consumed by the LED lamp 8 in real time, and calculates the power current value I_dummy consumed by the required dummy load circuit according to I_set and I_led: I_dummy=I_set-I_led;

[0044] The controller 5 updates the working gear of the dummy load circuit according to I_dummy.

[0045] The dummy load configuration current I_set is the minimum current value that the LED headlight control circuit power supply 7 needs to output in order to light up the vehicle's LED headlight 8. Each type of LED headlight dummy load system corresponds to a given dummy load configuration current I_set. In this embodiment, the controller 5 obtains the dummy load configuration current I_set of the LED headlight in the following manner:

[0046] An external configuration resistor R_set is pre-set on the vehicle;

[0047] The input end of the configuration resistor acquisition circuit 2 is connected to the external configuration resistor R_set, and the controller 5 calculates the resistance value of the configuration resistor R_set according to the output signal of the configuration resistor acquisition circuit 2;

[0048] The controller 5 obtains the dummy load configuration current I_set of the LED vehicle light corresponding to the resistance value of the external configuration resistor R_set by a table lookup method.

[0049] In other embodiments, the dummy load configuration current I_set is pre-written into the FLASH or EEPROM of the MCU.

[0050] In this embodiment, the controller 5 obtains the input current value I_led consumed by the LED lamp 8 in real time during operation in the following manner:

[0051] The controller 5 acquires the output voltage V_out of the LED lamp 8 and the power supply voltage V_bat of the LED lamp control circuit power supply 7 in real time, wherein V_out and V_bat are provided to the controller 5 by the LED voltage acquisition circuit 3 and the power supply voltage acquisition circuit 4 respectively;

[0052] The controller 5 calculates in real time the power current value I_led consumed by the LED light when it is working: I_led=V_out*I_out / V_bat, where I_out is the output current of the LED light. I_out is generated by the controller 5 controlling the LED driving circuit 6 in real time and is a known quantity for the controller 5.

[0053] In another embodiment, the controller 5 obtains the power current value I_led consumed by the LED lamp in real time when it is working in the following manner:

[0054] The controller 5 obtains the output voltage V_out of the LED lamp and the power supply voltage V_bat of the power supply of the LED lamp control circuit in real time;

[0055] The controller 5 calculates in real time the power current value I_led consumed by the LED light when it is working: I_led=V_out*I_out / V_bat1, where I_out is the output current of the LED light, V_bat1=V_bat+n, n is a preset voltage constant, and n>0.

[0056] In this another embodiment, by appropriately increasing the V_bat collected in real time when calculating the LED consumption current, the calculated I_led can be made smaller than the actual value, so that the calculated I_dummy will be larger, so that when the LED headlight 8 is working, the actual total power consumption current I_in (I_in is also the total input current of the LED headlight dummy load system, I_in = I_dummy + I_led) can be ensured to be greater than I_set, thereby reducing the probability of the vehicle reporting a headlight failure due to I_in being less than I_set.

[0057] After adopting the above technical solution, when the LED car light 8 is started, the controller 5 directly starts the corresponding working gear of the dummy load circuit according to the dummy load configuration current I_set, to ensure sufficient output current and avoid false alarm faults; when the LED car light 8 is working, the output voltage of the LED car light 8 is collected through the ADC module of the MCU5, and the real-time required current consumption of the dummy load circuit is calculated, thereby accurately controlling the size of the dummy load working current.

[0058] In this embodiment, the aforementioned LED car light 8 is an LED headlight. In other embodiments, the LED car light may also be an LED turn signal light or the like.

[0059] The above description is a further explanation of the present invention in combination with specific implementation methods and drawings. However, the present invention can obviously be implemented in a variety of other methods different from the description, and those skilled in the art can generalize and deduce according to actual usage without violating the content of the present invention. Therefore, the content of the above specific embodiments should not limit the protection scope determined by the present invention.

Claims

1. A method for automatically adjusting the dummy load of an LED vehicle lamp, characterized in that: include: Before the LED lamp works, the controller determines the working position of the dummy load circuit when the LED lamp is started according to the given dummy load configuration current I_set of the LED lamp, and adjusts the dummy load circuit to the working position; wherein the dummy load circuit has multiple working positions, and the consumption current of the dummy load circuit is different at different working positions; After the LED headlight is working, the controller obtains the power current value I_led consumed by the LED headlight in real time, and calculates the power current value I_dummy consumed by the required dummy load circuit according to I_set and I_led: I_dummy=I_set-I_led; The controller updates the working gear of the dummy load circuit according to I_dummy; The controller obtains the power current value I_led consumed by the LED lamp in real time when it is working, including: The controller obtains the output voltage V_out of the LED lamp and the power supply voltage V_bat of the LED lamp control circuit in real time; the controller calculates the power supply current value I_led consumed by the LED lamp when it is working in real time: I_led = V_out * I_out / V_bat, where I_out is the output current of the LED lamp; or, The controller obtains the output voltage V_out of the LED light and the power supply voltage V_bat of the LED light control circuit power supply in real time; the controller calculates the power current value I_led consumed when the LED light is working in real time: I_led = V_out * I_out / V_bat1, where I_out is the output current of the LED light, V_bat1= V_bat+n, n is a preset voltage constant, n>0.

2. The method for automatically adjusting the dummy load of an LED vehicle lamp according to claim 1, characterized in that: The controller obtains the given dummy load configuration current I_set of the LED lamp in the following manner: An external configuration resistor R_set is pre-set on the vehicle; The input end of the configuration resistor acquisition circuit is connected to the external configuration resistor, and the controller calculates the resistance value of the configuration resistor R_set according to the output signal of the configuration resistor acquisition circuit; The controller obtains the dummy load configuration current I_set of the LED vehicle lamp corresponding to the resistance value of the external configuration resistor R_set by a table lookup method.

3. The method for automatically adjusting the dummy load of an LED vehicle lamp according to claim 2, characterized in that: One end of the external configuration resistor R_set is grounded; The configuration resistor acquisition circuit includes a power supply VDD, a resistor R0 and a resistor R1, the output end of the power supply VDD is connected to one end of the resistor R0, one end of the resistor R1 is connected to the other end of the resistor R0, and the other end of the resistor R1 is connected to the AD sampling end of the controller; a common node between one end of the resistor R1 and the other end of the resistor R0 constitutes an input end of the configuration resistor acquisition circuit, and the other end of the resistor R1 constitutes an output end of the configuration resistor acquisition circuit; The input end of the configuration resistor acquisition circuit is connected to the other end of the external configuration resistor R_set, and the controller calculates the resistance value of the configuration resistor R_set according to the output voltage signal of the configuration resistor acquisition circuit.

4. A dummy load system for LED headlights, comprising a dummy load circuit, an LED driving circuit and a controller; the power input end of the dummy load circuit and the power input end of the LED driving circuit are respectively connected to the power supply of the LED headlight control circuit, the output end of the LED driving circuit is connected to the voltage input end of the LED headlight, and the first control output end of the controller is connected to the control input end of the LED driving circuit, characterized in that: The LED car light dummy load system also includes an LED voltage collection circuit and a power supply voltage collection circuit; The output end of the LED voltage acquisition circuit and the output end of the power supply voltage acquisition circuit are respectively connected to the first input end and the second input end of the controller; the LED voltage acquisition circuit is used to acquire the output voltage V_out of the LED lamp, and the power supply voltage acquisition circuit is used to acquire the power supply voltage V_bat of the power supply of the LED lamp control circuit in real time; The dummy load circuit has multiple working gears, and the current consumption of the dummy load circuit is different in different working gears; The second control output end of the controller is connected to the control input end of the dummy load circuit. The controller is used to determine the working gear of the dummy load circuit when the LED light is started according to the given dummy load configuration current I_set of the LED light before the LED light works, and adjust the dummy load circuit to the working gear; after the LED light works, calculate the power current value I_led consumed by the LED light when working in real time according to V_out and V_bat, and calculate the power current value I_dummy consumed by the required dummy load circuit in real time according to I_set and I_led, and update the working gear of the dummy load circuit according to the calculated I_dummy, I_dummy=I_set-I_led.

5. The LED vehicle lamp dummy load system according to claim 4, characterized in that: The controller is used to calculate the power current value I_led consumed when the LED lamp is working according to the following formula: I_led = V_out * I_out / V_bat; Alternatively, the controller is used to calculate the power current value I_led consumed by the LED lamp when it is working according to the following formula: I_led = V_out * I_out / V_bat1; Wherein, I_out is the output current of the LED headlight, V_bat1= V_bat+n, n is a preset voltage constant, n>0.

6. The LED vehicle lamp dummy load system according to claim 4, characterized in that: The dummy load circuit comprises a plurality of dummy load branches connected in parallel with each other, and power input ends of the plurality of dummy load branches are respectively connected to the power supply of the LED lamp control circuit; The second control output terminal of the controller is connected to the control input terminals of the plurality of dummy load branches respectively, so as to adjust the working gear of the dummy load circuit by controlling the number of the dummy load branches involved in the work.

7. The LED vehicle lamp dummy load system according to claim 6, characterized in that: Each dummy load branch includes a pull-up resistor, a grounding resistor, a switch current limiting resistor and a dummy load switch; One end of the pull-up resistor is connected to the power supply of the LED light control circuit, the other end of the pull-up resistor is connected to the first end of the dummy load switch, the second end of the dummy load switch is connected to one end of the grounding resistor, the other end of the grounding resistor is grounded, and the control end of the dummy load switch is connected to the second control output end of the controller through the switch current limiting resistor.

8. The LED vehicle lamp dummy load system according to claim 4, characterized in that: The LED car light dummy load system includes a configuration resistor collection circuit; The configuration resistor acquisition circuit includes a power supply VDD, a resistor R0 and a resistor R1, the output end of the power supply VDD is connected to one end of the resistor R0, one end of the resistor R1 is connected to the other end of the resistor R0, and the other end of the resistor R1 is connected to the third input end of the controller; A common node of one end of the resistor R1 and the other end of the resistor R0 constitutes an input end of the configuration resistor acquisition circuit, which is used to connect the other end of an external configuration resistor R_set pre-set on the vehicle, and one end of the external configuration resistor R_set is grounded; The controller is used to calculate the resistance value of the configuration resistor R_set according to the output voltage signal of the configuration resistor acquisition circuit, and obtain the dummy load configuration current I_set of the LED lamp corresponding to the resistance value of the external configuration resistor R_set by a table lookup method.

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