Motor driving circuit and dimming device using same

Abstract

The utility model relates to a motor drive circuit and a dimming device using the same. The drive circuit (20) comprises a controller (21) used for controlling the motor, a PWM conversion circuit (23) and an RC filter circuit (27). The PWM conversion circuit (23) comprises a voltage division circuit and a switching circuit, the voltage division circuit comprises a first transistor (Q1) and a pull-down resistor (R1) which are connected in series, and the first transistor (Q1) is electrically connected with a power supply (Vcc); the input end of the switching circuit receives a PWM signal, and the output end of the switching circuit conducts the first transistor (Q1) when the PWM signal is at a high potential, so that the node end of the pull-down resistor (R1) generates a voltage signal. And the input end of the RC filter circuit (27) receives the voltage signal, and the output end of the RC filter circuit (27) is connected to the controller (21). According to the utility model, the operation of the motor or the dimming device can be controlled according to the PWM signal, and the applicability and the flexibility of the product are improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of motor, more particularly, relates to motor drive circuit and the light adjusting device of application this kind drive circuit. BACKGROUND

[0002] The light adjusting device of car usually includes motor, gear drive mechanism that the output of motor is decelerated etc., the rotation condition of motor is controlled by voltage signal, in order to rotate the reflector cover of car headlamp to the angle that wants, thereby the light direction of car headlamp is adjusted to the direction that wants. The traditional fuel car usually is equipped with mechanical light adjusting switch, and the mechanical light adjusting switch is triggered to the corresponding voltage signal when being turned to different gears or being rotated to different angles. However, more and more new energy cars cancel mechanical light adjusting switch, no longer have traditional voltage signal, only pulse width modulation signal (PWM signal). A kind of solution is to increase conversion circuit in the control unit of car, and PMW signal is converted into voltage signal. But the defect of this scheme is that once conversion circuit fails, the corresponding control unit needs to be replaced, and the cost is high. Therefore, an optimal solution is urgently needed. SUMMARY

[0003] One object of the present application is to provide a motor drive circuit that can drive a motor according to a PWM signal.

[0004] To this end, the utility model provides a kind of motor drive circuit in the first aspect, including the controller for controlling motor, the controller is connected to power supply Vcc and ground;It further includes PWM conversion circuit and RC filter circuit, wherein: the PWM conversion circuit includes voltage dividing circuit and switch circuit, the voltage dividing circuit includes the first transistor Q1 and pull-down resistor R1 connected in series, and the first transistor Q1 is electrically connected with the power supply Vcc;The input end of the switch circuit receives PWM signal, and the output end of the switch circuit is turned on the first transistor Q1 when the PWM signal is high potential, so that the voltage signal is generated at the node end of the pull-down resistor R1;The input end of the RC filter circuit is used to receive the voltage signal, and the output end is connected to the controller.

[0005] In one embodiment of the utility model, the switch circuit includes the second transistor Q2 and pull-up resistor R2 connected in series, the power supply end of the pull-up resistor R2 is connected to the power supply Vcc, and the node end of the pull-up resistor R2 is used as the output end of the switch circuit;The second transistor Q2 is turned on when the high potential of the PWM signal, so that the node end of the pull-up resistor R2 can turn on the first transistor Q1.

[0006] In one embodiment of the utility model, the switch circuit further includes a first current limiting resistor R3 connected in series between the node end of the first transistor Q1 and the pull-up resistor R2.

[0007] In one embodiment of the utility model, the first transistor Q1 is a PNP type transistor, the emitter thereof is connected to the power supply Vcc, the collector thereof is connected to the node end of the pull-down resistor R1, and the base thereof is connected to the output end of the switch circuit.

[0008] In one embodiment of the utility model, the second transistor Q2 is an NPN type transistor, the emitter thereof is grounded, the collector thereof is connected to the node end of the pull-up resistor R2, and the base thereof receives the PWM signal.

[0009] In one embodiment of the utility model, a second current limiting resistor R4 is further connected in series to the base of the second transistor Q2, and the base of the second transistor Q2 receives the PWM signal through the second current limiting resistor R4.

[0010] In one embodiment of the utility model, a voltage dividing resistor is further included, one end of the voltage dividing resistor is grounded, the other end is connected to the base of the second transistor Q2, and the second current limiting resistor R4 is grounded through the series connection of the voltage dividing resistor R8.

[0011] In one embodiment of the utility model, the RC filter circuit includes two-stage filter circuits connected in series or multi-stage filter circuits connected in series; the first-stage filter circuit includes a first filter resistor R5 and a first ground capacitor C1, the input end of the first filter resistor (R5) is used for accepting the voltage signal, and the first ground capacitor (C1) grounds the output end of the first filter resistor (R5); each subsequent-stage filter circuit includes a corresponding filter resistor and a ground capacitor, the input end of the filter resistor of each subsequent-stage filter circuit is connected to the output end of the filter resistor of the previous-stage filter circuit, and the ground capacitor of each subsequent-stage filter circuit is used for grounding the output end of the filter resistor of the current-stage filter circuit; and the output end of the filter resistor of the last-stage filter circuit is connected to the controller.

[0012] In one embodiment of the utility model, a potentiometer connected to the feedback port of the controller is further included.

[0013] In one embodiment of the utility model, the PWM conversion circuit and the RC filter circuit are compatible with PWM signals of 200Hz to 1KHz.

[0014] The utility model discloses a second aspect provides a kind of light adjusting device, including motor, gear reduction mechanism for the output of the motor is decelerated, the gear reduction mechanism is used to rotate the reflector plate of light; It is characterized by further include the motor drive circuit of any one of the above.

[0015] The utility model discloses, can according to PWM signal control motor or the operation of light adjusting device, need not increase conversion circuit in the component of upper stage, for example, the control unit of car, improve the applicability and flexibility of product. BRIEF DESCRIPTION OF DRAWINGS

[0016] For further disclose the specific technical content of the case, please refer to the attached drawing, wherein:

[0017] Figure 1 The function module schematic diagram of motor drive circuit provided by an embodiment of the utility model is shown in the figure;

[0018] Figure 2 For Figure 1 A kind of change of motor drive circuit shown in the figure;

[0019] Figure 3 For Figure 1 A kind of circuit schematic diagram of motor drive circuit shown in the figure;

[0020] Figure 4 The schematic diagram of light adjusting device provided by an embodiment of the utility model is shown in the figure. DETAILED DESCRIPTION

[0021] The technical scheme in the embodiment of the utility model will be described below in conjunction with the drawings of the utility model.

[0022] Reference Figure 1 The motor drive circuit 20 provided by an embodiment of the utility model includes a controller 21 for controlling motor 10. The controller 21 is directly or indirectly connected to the power supply Vcc and the ground. The motor drive circuit 20 further includes a PWM conversion circuit 23 and an RC filter circuit 27. The PWM conversion circuit 23 is used to convert the PWM signal into a voltage signal. The input end of the RC filter circuit 27 receives the voltage signal, filters the voltage signal, and then transmits it to the controller 21. The controller 21 drives the motor 10 according to the filtered voltage signal. The feedback end of the controller 21 is connected to the potentiometer 29, which feeds back the running state of the motor 10. The motor drive circuit 20 of the embodiment has a PWM conversion circuit 23, which can convert the PWM signal into a motor signal, so that the motor 10 can be controlled by the PWM signal.

[0023] Reference Figure 2The PWM conversion circuit 23 comprises a voltage dividing circuit 24 and a switch circuit 25. The switch circuit 25 is used to control the running state of the voltage dividing circuit 24, such as on, off, amplification, etc. according to the PWM signal, so that the voltage dividing circuit 24 can generate a corresponding voltage signal.

[0024] With reference to Figure 3 The terminal 1 on the left side of the circuit diagram is used to connect the power supply Vcc. The terminal 2 on the left side of the circuit diagram is used to connect the control signal CMD, in which there is a PWM signal. The terminal 3 on the left side of the circuit diagram is grounded. With reference to Figure 2 and Figure 3 The voltage dividing circuit 24 comprises a first transistor Q1 and a pull-down resistor R1 connected in series, and the first transistor Q1 is electrically connected to the power supply Vcc. The input end of the switch circuit 25 receives the PWM signal, and the output end of the switch circuit is connected to the first transistor Q1 and turns on the first transistor Q1 when the PWM signal is high. When the first transistor Q1 is turned on, the current flows from the power supply Vcc through the first transistor Q1 to the pull-down resistor R1. The node end of the pull-down resistor R1 is equivalent to being connected to the power supply Vcc through the first transistor Q1, thereby having a certain voltage value, so that the aforementioned voltage signal can be generated. The node end of the pull-down resistor R1 serves as the output end of the voltage dividing circuit 24.

[0025] In this embodiment, the first transistor Q1 is a PNP type transistor, the emitter thereof is connected to the power supply Vcc, the collector thereof is connected to the node end of the pull-down resistor R1, and the base thereof is connected to the output end of the switch circuit 25. Understandably, when there is current flowing from the emitter to the base of the first transistor Q1, the first transistor Q1 is turned on.

[0026] In this embodiment, the switch circuit 25 comprises a second transistor Q2 and a pull-up resistor R2 connected in series, the power supply end of the pull-up resistor R2 is connected to the power supply Vcc, and the node end of the pull-up resistor R2 serves as the output end of the switch circuit 25. The second transistor Q2 is turned on when the PWM signal is high, and the current flows from the power supply Vcc through the pull-up resistor R2 to the second transistor Q2. At this time, there is a voltage difference between the two ends of the pull-up resistor R2, more specifically, the voltage at the node end of the pull-up resistor R2 is lower than that at the power supply end of the pull-up resistor R2, so that the node end of the pull-up resistor R2 can turn on the first transistor Q1.

[0027] In this embodiment, the second transistor Q2 is an NPN type transistor, the emitter thereof is grounded, the collector thereof is connected to the node end of the pull-up resistor R2, and the base thereof receives the PWM signal. When the PWM signal is high, there is current flowing from the base to the emitter of the second transistor Q2, thereby turning on the second transistor Q2.

[0028] In the embodiment, the switch circuit 25 further comprises a first current-limiting resistor R3 connected in series between the node end of the first transistor Q1 and the node end of the pull-up resistor R2 for protecting the first transistor Q1. Understandably, the switch circuit 25 can further comprise a second current-limiting resistor R4 connected in series to the base of the second transistor Q2, and the base of the second transistor Q2 receives the PWM signal through the second current-limiting resistor R4.

[0029] In the embodiment, the switch circuit 25 further comprises a voltage-dividing resistor R8, one end of which is grounded and the other end of which is connected to the base of the second transistor Q2, so that the second current-limiting resistor R4 is connected to the ground through the voltage-dividing resistor R8 in series. In this way, when the PWM signal is at a high level, the second current-limiting resistor R4 and the voltage-dividing resistor R8 are connected in series and turned on, and a voltage difference exists between the voltage-dividing resistor R8, and the value of the voltage difference is related to the percentage of the resistance value of the voltage-dividing resistor R8 in the resistance value of the second current-limiting resistor R4. Therefore, by designing the resistance values of the second current-limiting resistor R4 and the voltage-dividing resistor R8, a desired voltage difference can be obtained between the voltage-dividing resistor R8, so as to control the voltage value of the base of the second transistor Q2 relative to the emitter of the second transistor Q2.

[0030] In the embodiment, because one end of the voltage-dividing resistor R8 is grounded, the voltage-dividing resistor R8 belongs to a pull-down resistor. When there is no input signal or the input signal is at a high resistance state at the left end of the circuit diagram, the voltage-dividing resistor R8 can pull down the potential of the base of the second transistor Q2 to a low level, so as to ensure that the second transistor Q2 is in an off state, prevent interference signals from being introduced into the base of the second transistor Q2 due to the floating state, avoid the second transistor Q2 from being turned on due to signal interference, and improve the anti-interference ability of the switch circuit 25. In addition, when there is no input signal or the input signal is at a high resistance state at the left end of the circuit diagram, the voltage-dividing resistor R8 pulls down the base of the second transistor Q2 to a low level, so as to ensure that the default state of the second transistor Q2 is an off state.

[0031] The voltage-dividing resistor R8 also has the effect of accelerating the switching process of the second transistor Q2. For example, when the second transistor Q2 switches from a turned-on state to an off state, the voltage-dividing resistor R8 can provide a rapid discharge path for the base charge of the second transistor Q2, reduce the switching jitter and parasitic oscillation of the second transistor Q2, accelerate the off process of the second transistor Q2, reduce the switching time, and improve the switching speed and efficiency of the circuit.

[0032] In the embodiment, the RC filter circuit 27 comprises a plurality of filter circuits connected in series, and the first-stage filter circuit comprises a first filter resistor R5 and a first ground capacitor C1. The input end of the first filter resistor R5 is connected to the node end of the pull-down resistor R1 for receiving the aforementioned voltage signal, and the output end of the first filter resistor R5 is grounded by the first ground capacitor C1.

[0033] The second stage filter circuit of the RC filter circuit 27 comprises a second filter resistor R6 and a second ground capacitor C2, the input end of the second filter resistor R6 is connected to the output end of the first filter resistor R5, and the second ground capacitor C2 grounds the output end of the second filter resistor R6. The third stage filter circuit comprises a third filter resistor R7 and a third ground capacitor C3, the input end of the third filter resistor R7 is connected to the output end of the second filter resistor R6, and the third ground capacitor C3 grounds the output end of the third filter resistor R7. The output end of the third filter resistor R7 serves as the output end of the entire RC filter circuit 27 and is connected to the controller 21, that is Figure 3 The integrated circuit (IC) module shown.

[0034] In this embodiment, the RC filter circuit 27 comprises three stages of filter circuits in series, which improves the filtering performance and makes the motor driving circuit 20 or the motor 10 compatible with PWM signals of 200 Hz to 1 KHz, thereby improving the applicability and flexibility of the product. Understandably, the RC filter circuit 27 can comprise fewer or more stages of filter circuits in series, such as one stage, two stages, three stages, or more than three stages. In the case of two or more stages of filter circuits, the first stage filter circuit comprises a first filter resistor R5 and a first ground capacitor C1, and each subsequent stage of filter circuit comprises a corresponding filter resistor and ground capacitor. The input end of the filter resistor of each stage of filter circuit is connected to the output end of the filter resistor of the previous stage of filter circuit, and the ground capacitor of each stage of filter circuit is used to ground the output end of the filter resistor of the stage of filter circuit. The output end of the filter resistor of the last stage of filter circuit is connected to the controller

[0035] Reference Figure 4 In another embodiment of the utility model, the dimming device comprises a motor 10, a motor driving circuit 20 for controlling the motor 10, and a gear reduction mechanism 50 for reducing the output of the motor 10, which is used to rotate the reflector plate of the lighting lamp (not shown in the figure). As described above, the motor driving circuit 20 can receive PWM signals to control the operation of the motor 10, so that the dimming device can be adapted to new energy vehicles.

[0036] The above-described embodiments only express several implementation manners of the application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the patent scope of the application. It should be noted that, for ordinary skilled persons in the art, without departing from the concept of the application, several modifications and improvements can be made, which all belong to the protection scope of the application. Therefore, the patent protection scope of the application should be subject to the appended claims.

Claims

1. An electric motor drive circuit comprising a controller (21) for controlling an electric motor (10), the controller (21) being connected to a power supply (Vcc) and to ground; characterized in that, Also comprising: a PWM conversion circuit (23), the PWM conversion circuit (23) comprising a voltage dividing circuit (24) and a switching circuit (25), the voltage dividing circuit (24) comprising a first transistor (Q1) and a pull-down resistor (R1) connected in series, the first transistor (Q1) being electrically connected to the power supply (Vcc); the switching circuit (25) receiving a PWM signal at its input end, and turning on the first transistor (Q1) at its output end when the PWM signal is high, so that a voltage signal is generated at the node end of the pull-down resistor (R1); an RC filter circuit (27) having an input end for receiving the voltage signal and an output end connected to the controller (21).

2. The motor drive circuit of claim 1, wherein, The switching circuit (25) comprises a second transistor (Q2) and a pull-up resistor (R2) connected in series, the pull-up resistor (R2) having a power supply end connected to the power supply (Vcc) and a node end as the output end of the switching circuit (25); the second transistor (Q2) being turned on when the PWM signal is high, so that the node end of the pull-up resistor (R2) can turn on the first transistor (Q1).

3. The motor drive circuit of claim 2, wherein, The switching circuit (25) further comprises a first current limiting resistor (R3) connected in series between the first transistor (Q1) and the node end of the pull-up resistor (R2).

4. The motor drive circuit of claim 2, wherein, The first transistor (Q1) is a PNP transistor, the emitter of which is connected to the power supply (Vcc), the collector of which is connected to the node end of the pull-down resistor (R1), and the base of which is connected to the output end of the switching circuit.

5. The motor drive circuit of claim 2, wherein, The second transistor (Q2) is an NPN transistor, the emitter of which is grounded, the collector of which is connected to the node end of the pull-up resistor (R2), and the base of which receives the PWM signal.

6. The motor drive circuit of claim 5, wherein, A second current limiting resistor (R4) is further connected in series to the base of the second transistor (Q2), and the base of the second transistor (Q2) receives the PWM signal through the second current limiting resistor (R4).

7. The motor drive circuit of claim 6, wherein, A voltage dividing resistor (R8) is further connected, one end of which is grounded and the other end of which is connected to the base of the second transistor (Q2), so that the second current limiting resistor (R4) is connected to ground through the voltage dividing resistor (R8).

8. The motor drive circuit of claim 1, wherein, The RC filter circuit (27) comprises two-stage filter circuits or multi-stage filter circuits connected in series; the first-stage filter circuit comprises a first filter resistor (R5) and a first ground capacitor (C1), the input end of the first filter resistor (R5) being used to receive the voltage signal, and the first ground capacitor (C1) grounding the output end of the first filter resistor (R5); each subsequent-stage filter circuit comprises a corresponding filter resistor and a ground capacitor, the input end of the filter resistor of each subsequent-stage filter circuit being connected to the output end of the filter resistor of the previous-stage filter circuit, and the ground capacitor of each subsequent-stage filter circuit being used to ground the output end of the filter resistor of the present-stage filter circuit; the output end of the filter resistor of the last-stage filter circuit being connected to the controller (21).

9. The motor drive circuit of claim 1, wherein, Also included is a potentiometer (29) connected to a feedback port of the controller (21).

10. A light adjusting device comprising a motor (10), a gear reduction mechanism (50) for reducing the output of the motor (10), the gear reduction mechanism (50) being used to rotate a reflector of a light; characterized in that, Also included is the motor drive circuit of any one of claims 1 to 9.

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