A 24V system automotive headlight dimming motor circuit

Abstract

This invention proposes a 24V system automotive headlight dimming motor circuit, including a power protection module with its input terminal connected to the power input signal; a voltage regulation and filtering module, including a connected switching circuit and a filtering circuit, with the switching circuit connected to the output terminal of the power protection module and the PWM control signal respectively. The switching circuit converts the PWM control signal at the signal terminal into a power-end PWM control signal with the same state and potential as the power input signal, and the filtering circuit filters the power-end PWM control signal to obtain a stable level signal; and a driving module, including a connected driving chip and a driving circuit, both connected to the power protection module and the filtering circuit respectively. The driving circuit includes a feedback potentiometer connected to the driving chip. This invention is applicable to 24V dimming motors and can operate safely and stably.

Description

Technical Field

[0001] This utility model relates to the technical field of automotive headlight components, and in particular to an automotive headlight dimming motor circuit. Background Technology

[0002] As the most common mode of transportation, automobiles are subject to increasingly higher safety requirements. Regarding headlights, national standards have specific requirements for their beam height to improve nighttime driving safety. To address changes in headlight beam height caused by variations in vehicle weight, a dimming motor, as an essential component, is commonly installed within the headlight. The dimming motor works by using control signals from the vehicle body to drive an internal motor via a control circuit. The internal gear system converts the motor's axial rotation into linear motion of the output screw. This output screw is connected to the headlight reflector; its linear motion causes the reflector to move axially, thus adjusting the headlight beam height and ensuring driving safety.

[0003] With the increasing electrification and intelligence of automobiles, the control signals from the vehicle body have gradually shifted from DC regulated signals to PWM digital signals. These PWM signal dimming motors are already widely used in the 12V passenger vehicle market. However, for the 24V commercial vehicle market, the voltage specifications and load characteristics of the 24V system differ significantly from those of the 12V system. Directly using the 12V system's circuit design is not feasible. Therefore, PWM signal dimming motors also require compatible dimming motor circuits. Utility Model Content

[0004] To address the issue that the PWM digital control signal output from the vehicle body cannot be effectively adapted to the 24V dimming motor technology, this utility model proposes a 24V system automotive headlight dimming motor circuit to provide a safe and stable drive output for the 24V dimming motor.

[0005] To achieve the above objectives, the technical solution of this utility model is implemented as follows: A 24V system automotive headlight dimming motor circuit includes: The power protection module has its input terminal connected to the power input signal; The voltage regulation and filtering module includes a switching circuit and a filtering circuit connected together. The switching circuit is connected to the output terminal and the signal terminal PWM control signal of the power protection module respectively. The switching circuit is used to convert the signal terminal PWM control signal into a power terminal PWM control signal that is consistent with the state and potential of the power input signal. The filtering circuit is used to filter the power terminal PWM control signal to obtain a stable level signal. The driving module includes a driving chip and a driving circuit connected to each other. The driving chip and the driving circuit are respectively connected to the power protection module and the filtering circuit. The driving circuit includes a feedback potentiometer connected to the driving chip. The driving circuit obtains a reference signal based on a stable level signal. The driving chip controls the dimming motor to work based on the reference signal and the feedback signal from the feedback potentiometer.

[0006] Specifically, the power protection module includes a reverse power connection prevention unit, a transient surge protection unit, and a filtering unit connected in sequence. The reverse power connection prevention unit is connected to the power input signal, and the filtering unit is connected to the switching circuit, the driver chip, and the driver circuit, respectively.

[0007] Specifically, the switching circuit includes a reverse protection diode D3, a first-stage transistor circuit, and a second-stage transistor circuit connected in sequence. The anode of the reverse protection diode D3 is connected to the PWM control signal at the signal terminal, and the second-stage transistor circuit is connected to the filter circuit and the filter unit respectively. The filtering circuit described is a multi-stage RC filtering circuit.

[0008] Specifically, the reverse connection prevention unit is diode D1, and the anode of diode D1 is connected to the power input signal; The transient shock protection unit is a bidirectional TVS diode D2. One end of the bidirectional TVS diode D2 is connected to the cathode of the diode D1, and the other end of the bidirectional TVS diode D2 is grounded. The filtering unit includes a polarized capacitor C1 and a non-polarized capacitor C2. The polarized capacitor C1 is used to filter out low-frequency ripple in the power supply, and the non-polarized capacitor C2 is used to filter out high-frequency noise. The positive terminal of the polarized capacitor C1 is connected to the cathode of the diode D1, and the negative terminal of the polarized capacitor C1 is grounded. One end of the non-polarized capacitor C2 is connected to the cathode of the diode D1 and the second-stage transistor circuit, and the other end of the non-polarized capacitor C2 is grounded.

[0009] Specifically, the first-stage transistor circuit includes a first transistor Q1. The base of the first transistor Q1 is connected to one end of voltage divider resistor R1 and one end of voltage divider resistor R2, respectively. The other end of voltage divider resistor R1 is connected to the cathode of the anti-reverse diode D3. The other end of voltage divider resistor R2 is connected to the emitter of the first transistor Q1 and then grounded together. The collector of the first transistor Q1 is connected to the second-stage transistor circuit through one end of resistor R3.

[0010] Specifically, the second-stage transistor circuit includes a second transistor Q2. The base of the second transistor Q2 is connected to the other end of resistor R3 and one end of resistor R4, respectively. The other end of resistor R4 is connected to the output terminal of the filter unit. The emitter of the second transistor Q2 is connected to one end of resistor R5, and the other end of resistor R5 is connected to the filter unit. The collector of the second transistor Q2 is connected to one end of resistor R6 and the multi-stage RC filter circuit, and the other end of resistor R6 is grounded.

[0011] Specifically, the multi-stage RC filter circuit includes a first RC filter circuit, a second RC filter circuit, and a third RC filter circuit connected in sequence. The first RC filter circuit is connected to the second-stage transistor circuit, and the third RC filter circuit is connected to the driving circuit and the driving chip, respectively.

[0012] Specifically, the driving circuit includes a signal input circuit and a signal output circuit of the driving chip. The signal input circuit of the driving chip includes a feedback signal input circuit and a reference signal input circuit. The feedback signal input circuit is connected to the signal feedback pin of the driving chip and the filtering unit, respectively. The reference signal input circuit is connected to the reference signal pin of the driving chip and the output terminal of the third RC filter circuit, respectively. The signal output circuit is connected to the output terminal of the driving chip and the dimming motor, respectively.

[0013] Specifically, the feedback signal input circuit includes a feedback potentiometer and a resistor R12. The first fixed terminal of the feedback potentiometer is connected to the filter unit, the second fixed terminal of the feedback potentiometer is grounded, the sliding terminal of the feedback potentiometer is connected to one end of the resistor R12, and the other end of the resistor R12 is connected to the signal feedback pin of the driver chip. The reference signal input circuit includes a resistor R11. One end of the resistor R11 is connected to the output of the third RC filter circuit, and the other end of the resistor R11 is connected to the reference signal pin of the driver chip.

[0014] Specifically, the signal input circuit includes connected voltage divider resistors R13 and R14. The connection end of voltage divider resistors R13 and R14 is connected to the hysteresis pin HYST of the driver chip; the other end of voltage divider resistor R13 is connected to the filter unit; and the other end of voltage divider resistor R14 is grounded. The signal input circuit also includes a resistor R10, one end of which is connected to the output of the third RC filter circuit, and the other end of which is connected to the RANGE pin of the driver chip. A capacitor C3 is connected to the other end of the resistor R12 and the other end of the resistor R11.

[0015] The beneficial effects of this utility model are as follows: This invention fills a technological gap in the 24V commercial vehicle market, adapts to PWM signal requirements, and accurately converts different external PWM signals into stable control signals that can be recognized by the 24V dimming motor through a voltage regulation and filtering module, while providing a safe and stable drive output for the 24V dimming motor. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the circuit structure of this utility model. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0019] Example 1 A 24V system automotive headlight dimming motor circuit, such as Figure 1 As shown, it includes: The power protection module has its input terminal connected to the power input signal; it is used to prevent reverse power connection, protect against transient impacts, and filter signals.

[0020] The voltage regulation and filtering module includes a switching circuit and a filtering circuit connected together. The switching circuit is connected to the output terminal and the signal terminal PWM control signal of the power protection module respectively. The switching circuit is used to convert the signal terminal PWM control signal into a power terminal PWM control signal that is consistent with the power input signal level. The filtering circuit is used to filter the power terminal PWM control signal to obtain a stable level signal. The driving module includes a driving chip and a driving circuit connected to each other. The driving chip and the driving circuit are respectively connected to the power protection module and the filtering circuit. The driving circuit includes a feedback potentiometer connected to the driving chip. The driving circuit obtains a reference signal based on a stable level signal. The driving chip controls the dimming motor to work based on the reference signal and the feedback signal from the feedback potentiometer.

[0021] Example 2 Based on Example 1, a 24V system automotive headlight dimming motor circuit, such as... Figure 1 As shown: The power protection module includes a reverse power connection prevention unit, a transient surge protection unit, and a filtering unit connected in sequence. The reverse power connection prevention unit is connected to the power input signal, and the filtering unit is connected to the switching circuit, the driver chip, and the driver circuit, respectively.

[0022] The reverse connection prevention unit is a diode D1, and the anode of diode D1 is connected to the power input signal.

[0023] The aforementioned transient surge protection unit is a bidirectional TVS diode D2. One end of the bidirectional TVS diode D2 is connected to the cathode of the diode D1, and the other end of the bidirectional TVS diode D2 is grounded. When a surge occurs in the vehicle body circuit, such as a transient high voltage during ignition, the bidirectional TVS diode D2 breaks down and short-circuits instantly, discharging the high voltage to ground and preventing the high voltage from damaging subsequent chips.

[0024] The filtering unit includes a polarized capacitor C1 and a non-polarized capacitor C2. The polarized capacitor C1 is an electrolytic capacitor, and the non-polarized capacitor C2 is a ceramic capacitor. The polarized capacitor C1 is used to filter out low-frequency ripple in the power supply, and the non-polarized capacitor C2 is used to filter out high-frequency noise. The positive terminal of the polarized capacitor C1 is connected to the cathode of the diode D1, and the negative terminal of the polarized capacitor C1 is grounded. One end of the non-polarized capacitor C2 is connected to the cathode of the diode D1 and the second-stage transistor circuit, and the other end of the non-polarized capacitor C2 is grounded.

[0025] Example 3 Based on Example 2, a 24V system automotive headlight dimming motor circuit, such as... Figure 1 As shown: The switching circuit includes a reverse protection diode D3, a first-stage transistor circuit, and a second-stage transistor circuit connected in sequence. The anode of the reverse protection diode D3 is connected to the PWM control signal at the signal terminal. The second-stage transistor circuit is connected to the filter circuit and the filter unit respectively. The switching circuit composed of the first-stage transistor circuit and the second-stage transistor circuit converts the input PWM control signal at the signal terminal into a PWM control signal at the power supply terminal that is consistent with the state and potential of the power input signal. When the power supply signal fluctuates, it ensures that the PWM control signal at the power supply terminal changes simultaneously with the power supply signal, thereby ensuring that the reference signal and the feedback potentiometer feedback signal change simultaneously. This avoids the frequent control of the dimming motor rotation by the driver chip when the PWM control signal at the signal terminal and the power supply signal are inconsistent, which would cause the headlight pattern of the car to flicker. At the same time, the switching circuit composed of the first-stage transistor circuit and the second-stage transistor circuit can boost the 12V PWM control signal to a PWM signal at the same potential as the power supply signal, ensuring that the driving requirements of the 24V motor driver chip are met.

[0026] The first-stage transistor circuit includes a first transistor Q1. The base of the first transistor Q1 is connected to voltage divider resistors R1 and R2, respectively. Voltage divider resistor R1 is connected to the cathode of the anti-reverse diode D3. Voltage divider resistor R2 is connected to the emitter of the first transistor Q1 and then grounded together. Voltage divider resistors R1 and R2 reduce the amplitude of the PWM signal to avoid damage to the switching transistors Q1 / Q2 due to excessive voltage. The collector of the first transistor Q1 is connected to the second-stage transistor circuit through resistor R3.

[0027] The second-stage transistor circuit includes a second transistor Q2. The base of transistor Q2 is connected to resistors R3 and R4, respectively. Resistor R4 is connected to the filter unit. The emitter of transistor Q2 is connected to resistor R5, which is also connected to the filter unit. The collector of transistor Q2 is connected to resistor R6 and the multi-stage RC filter circuit. When the first transistor Q1 is turned on, resistors R3 and R4 form a voltage divider circuit, ensuring that Q2 can effectively enter the saturation region. When the second transistor Q2 is turned on, resistors R5 and R6 form a voltage divider circuit, controlling the high-level input value of the downstream multi-stage RC filter circuit. By controlling the input level value, the input value of the REF pin of the driver chip can be controlled. Whether the motor moves is determined by comparing the input value of the REF pin and the input value of the FB pin. The input value of the FB pin is provided by potentiometer W1 and has a linear relationship with the product displacement. Therefore, by changing the ratio of resistors R5 and R6, the linearity requirements of customers with the same architecture but different products can be met.

[0028] Example 4 Based on Example 3, a 24V system automotive headlight dimming motor circuit, such as... Figure 1 As shown: The filtering circuit described is a multi-stage RC filtering circuit.

[0029] The multi-stage RC filter circuit includes a first RC filter circuit, a second RC filter circuit, and a third RC filter circuit connected in sequence. The first RC filter circuit is connected to the second-stage transistor circuit. In the first RC filter circuit, resistor R7 is connected to the collector of the second transistor Q2, and capacitor C5 is grounded. The connection between resistor R7 and capacitor C5 is connected to resistor R8 in the second RC filter circuit, and capacitor C6 is grounded. The connection between resistor R8 and capacitor C6 is connected to resistor R9 in the third RC filter circuit, and capacitor C7 is grounded. The connection between resistor R9 and capacitor C7 is connected to the drive circuit. Using multi-stage RC filtering can more thoroughly filter out the AC component of the PWM pulse, retaining the DC level proportional to the duty cycle.

[0030] Example 5 Based on Example 4, a 24V system automotive headlight dimming motor circuit, such as... Figure 1 As shown: The driving circuit includes a signal input circuit and a signal output circuit for the driving chip. The signal input circuit includes a feedback signal input circuit and a reference signal input circuit. The feedback signal input circuit is connected to the signal feedback pin of the driving chip and the filtering unit, respectively. The reference signal input circuit is connected to the reference signal pin of the driving chip and the output terminal of the third RC filter circuit, respectively. The signal output circuit is connected to the output terminal of the driving chip and the dimming motor, respectively. In this embodiment, the driving chip used is the DS4210, a dedicated 24V motor driving chip with a built-in comparator and power driving circuit, capable of receiving analog voltage signals and outputting sufficient current to drive the motor.

[0031] The feedback signal input circuit includes a feedback potentiometer and a resistor R12. The first fixed terminal of the feedback potentiometer is connected to the filter unit, the second fixed terminal of the feedback potentiometer is grounded, the sliding terminal of the feedback potentiometer is connected to one end of the resistor R12, and the other end of the resistor R12 is connected to the signal feedback pin of the driver chip.

[0032] The reference signal input circuit includes a resistor R11. One end of the resistor R11 is connected to the output of the third RC filter circuit, and the other end of the resistor R11 is connected to the reference signal pin of the driver chip.

[0033] The signal input circuit includes connected voltage divider resistors R13 and R14. The connection terminals of R13 and R14 are connected to the hysteresis pin (HYST) of the driver chip. The driver chip only determines the signal is valid and drives the motor when the difference between the REF and FB input values ​​exceeds the HYST setting range. Changing the voltage division ratio of R13 and R14 alters the HYST determination range. This allows adjustment of the HYST range based on the stability of the vehicle body signal, meeting the requirements for stable lighting. The other end of voltage divider resistor R13 is connected to the positive terminal of the polarized capacitor C1 and one end of the non-polarized capacitor C2 in the filter unit.

[0034] The signal input circuit also includes resistor R10. One end of resistor R10 is connected to the output terminal of the third RC filter circuit, i.e., the connection point between resistor R9 and capacitor C7. The other end of resistor R10 is connected to the RANGE pin of the driver chip. The driver chip has a built-in function to determine whether the input signal is shorted to ground or power supply. This determination range is adjusted via the RANGE pin. In other words, adjusting the RANGE pin can adjust the range of valid signals received by the REF pin.

[0035] A capacitor C3 is connected to the other end of the resistor R12 and the other end of the resistor R11.

[0036] The signal output circuit includes capacitor C4, which is connected to the output terminals OUT1 and OUT2 of the driver chip respectively; capacitors C3 and C4 can effectively ensure the stability of the input signal and output voltage of the driver chip.

[0037] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A 24V system automotive headlight dimming motor circuit, characterized in that, include: The power protection module has its input terminal connected to the power input signal; The voltage regulation and filtering module includes a switching circuit and a filtering circuit connected together. The switching circuit is connected to the output terminal and the signal terminal PWM control signal of the power protection module respectively. The switching circuit is used to convert the signal terminal PWM control signal into a power terminal PWM control signal that is consistent with the state and potential of the power input signal. The filtering circuit is used to filter the power terminal PWM control signal to obtain a stable level signal. The driving module includes a driving chip and a driving circuit connected to each other. The driving chip and the driving circuit are respectively connected to the power protection module and the filtering circuit. The driving circuit includes a feedback potentiometer connected to the driving chip. The driving circuit obtains a reference signal based on a stable level signal. The driving chip controls the dimming motor to work based on the reference signal and the feedback signal from the feedback potentiometer.

2. The 24V system automotive headlight dimming motor circuit according to claim 1, characterized in that, The power protection module includes a reverse power connection prevention unit, a transient surge protection unit, and a filtering unit connected in sequence. The reverse power connection prevention unit is connected to the power input signal, and the filtering unit is connected to the switching circuit, the driver chip, and the driver circuit, respectively.

3. The 24V system automotive headlight dimming motor circuit according to claim 2, characterized in that, The switching circuit includes a reverse protection diode D3, a first-stage transistor circuit, and a second-stage transistor circuit connected in sequence. The anode of the reverse protection diode D3 is connected to the PWM control signal at the signal terminal. The second-stage transistor circuit is connected to the filter circuit and the filter unit respectively. The filtering circuit described is a multi-stage RC filtering circuit.

4. The 24V system automotive headlight dimming motor circuit according to claim 2, characterized in that, The reverse connection prevention unit is diode D1, and the anode of diode D1 is connected to the power input signal; The transient shock protection unit is a bidirectional TVS diode D2. One end of the bidirectional TVS diode D2 is connected to the cathode of the diode D1, and the other end of the bidirectional TVS diode D2 is grounded. The filtering unit includes a polarized capacitor C1 and a non-polarized capacitor C2. The polarized capacitor C1 is used to filter out low-frequency ripple in the power supply, and the non-polarized capacitor C2 is used to filter out high-frequency noise. The positive terminal of the polarized capacitor C1 is connected to the cathode of the diode D1, and the negative terminal of the polarized capacitor C1 is grounded. One end of the non-polarized capacitor C2 is connected to the cathode of the diode D1 and the second-stage transistor circuit, and the other end of the non-polarized capacitor C2 is grounded.

5. The 24V system automotive headlight dimming motor circuit according to claim 3, characterized in that, The first-stage transistor circuit includes a first transistor Q1. The base of the first transistor Q1 is connected to one end of voltage divider resistor R1 and one end of voltage divider resistor R2, respectively. The other end of voltage divider resistor R1 is connected to the cathode of the anti-reverse diode D3. The other end of voltage divider resistor R2 is connected to the emitter of the first transistor Q1 and then grounded together. The collector of the first transistor Q1 is connected to the second-stage transistor circuit through one end of resistor R3.

6. The 24V system automotive headlight dimming motor circuit according to claim 5, characterized in that, The second-stage transistor circuit includes a second transistor Q2. The base of the second transistor Q2 is connected to the other end of resistor R3 and one end of resistor R4, respectively. The other end of resistor R4 is connected to the output terminal of the filter unit. The emitter of the second transistor Q2 is connected to one end of resistor R5, and the other end of resistor R5 is connected to the filter unit. The collector of the second transistor Q2 is connected to one end of resistor R6 and the multi-stage RC filter circuit, respectively. The other end of resistor R6 is grounded.

7. The 24V system automotive headlight dimming motor circuit according to any one of claims 3, 5, or 6, characterized in that, The multi-stage RC filter circuit includes a first RC filter circuit, a second RC filter circuit, and a third RC filter circuit connected in sequence. The first RC filter circuit is connected to the second-stage transistor circuit, and the third RC filter circuit is connected to the driving circuit and the driving chip, respectively.

8. The 24V system automotive headlight dimming motor circuit according to claim 6, characterized in that, The driving circuit includes a signal input circuit and a signal output circuit of the driving chip. The signal input circuit of the driving chip includes a feedback signal input circuit and a reference signal input circuit. The feedback signal input circuit is connected to the signal feedback pin of the driving chip and the filtering unit, respectively. The reference signal input circuit is connected to the reference signal pin of the driving chip and the output terminal of the third RC filter circuit, respectively. The signal output circuit is connected to the output terminal of the driving chip and the dimming motor, respectively.

9. The 24V system automotive headlight dimming motor circuit according to claim 8, characterized in that, The feedback signal input circuit includes a feedback potentiometer and a resistor R12. The first fixed terminal of the feedback potentiometer is connected to the filter unit, the second fixed terminal of the feedback potentiometer is grounded, the sliding terminal of the feedback potentiometer is connected to one end of the resistor R12, and the other end of the resistor R12 is connected to the signal feedback pin of the driver chip. The reference signal input circuit includes a resistor R11. One end of the resistor R11 is connected to the output of the third RC filter circuit, and the other end of the resistor R11 is connected to the reference signal pin of the driver chip.

10. The 24V system automotive headlight dimming motor circuit according to claim 9, characterized in that, The signal input circuit includes connected voltage divider resistors R13 and R14. The connection end of voltage divider resistors R13 and R14 is connected to the hysteresis pin HYST of the driver chip; the other end of voltage divider resistor R13 is connected to the filter unit; and the other end of voltage divider resistor R14 is grounded. The signal input circuit also includes a resistor R10, one end of which is connected to the output of the third RC filter circuit, and the other end of which is connected to the RANGE pin of the driver chip. A capacitor C3 is connected to the other end of the resistor R12 and the other end of the resistor R11.

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