Self-adaptive buck-boost driving circuit, driving method and automobile lamp

Abstract

The invention belongs to the technical field of electronic circuits, and particularly relates to a self-adaptive buck-boost driving circuit, a driving method and an automobile lamp. The self-adaptive boost-buck driving circuit comprises a master controller, a Boost circuit and a load, wherein the positive electrode of the load is connected with the positive output end of the Boost circuit; the drain electrode of the first switch tube is connected with the negative electrode of the load, the source electrode is grounded, and the grid electrode is connected with the master control; the positive electrode of the first diode is connected with the drain electrode of the first switch tube, and the negative electrode is connected with the power supply end of the Boost circuit. According to the invention, the circuit can be automatically switched to a boost state or a buck-boost state according to the condition of the accessed load, the boost characteristic of the Boost circuit is fully played, the power supply efficiency is optimized, the load access condition does not need to be confirmed during wiring, the wiring mode of workers is simplified, and the yield is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic circuits, and in particular relates to an adaptive buck-boost driving circuit, a driving method and an automobile lamp. Background Art

[0002] The car headlight driver board is generally powered by a voltage of about 12V. However, due to the different number of LED strings used in different car headlights, the voltage to drive a string of LEDs is about 3V. If the number of LED strings in the car headlight is less than 4, the total voltage to drive the LEDs is less than 12V, so the car headlight driver board needs to step down the voltage to drive the LEDs; if the number of LED strings in the car headlight is greater than 4, the total voltage to drive the LEDs is greater than 12V, so the car headlight driver board needs to step up the voltage to drive the LEDs. In other words, the car headlight driver board needs to implement the step-up and step-down function to drive different numbers of LEDs.

[0003] There are two solutions currently. One is to use a 4-switch Buck-Boost circuit to achieve the buck-boost function. Refer to the application circuit as shown in Figure 1 As shown in the figure, the advantage of this circuit is that it can realize step-up and step-down by controlling the switch state of 4 switch tubes, so as to drive different strings of LEDs. However, the disadvantages of this circuit are also obvious. It uses 4 MOS tubes, which is costly and complex to control. In addition, the reliability of this bridge structure is poor. Once the upper and lower tubes are directly connected, the MOS tubes will burn out. Another most commonly used solution is to use a Boost circuit to realize the step-up and step-down function, so that the Boost circuit works in the step-up and step-down state. For reference, the application circuit is as follows: Figure 2 Connect LED- back to the positive pole of the input power supply. The reason for this is that the Boost circuit can only achieve voltage boost. Connect LED- back to the positive pole of the input power supply. In this way, the actual output voltage is equal to the voltage dropped on the total LED plus the voltage of the input power supply. That is, the output voltage must be greater than the input voltage, ensuring that the Boost circuit can work normally. Figure 2 The current path through the LED is also marked. Figure 2 In the circuit, Q1 is a MOS tube that realizes the buck-boost function, and Q2 is a MOS tube that realizes the dimming function. The advantage of this circuit is that it only uses one MOS tube Q1 to realize the buck-boost function, which is low cost, simple to control, and reliable. The disadvantage is that the output voltage is the superposition of the voltage on the LED load and the input voltage, sacrificing part of the boost characteristic of the Boost circuit in vain, especially when the number of LED strings is much larger than 4 strings, such as when the LED lamp is 12 strings, the voltage on the LED is about 36V, and the efficiency of this connection method will be relatively low. In order to optimize the efficiency, the wiring workers will carefully confirm the number of LED lamp beads in string before wiring. If it is confirmed that the number of LED lamp beads in string is less than 6 strings, follow Figure 2If the number of LED lamp beads is confirmed to be more than 6, the wiring worker will connect LED+ to Figure 2 position as shown, but connects LED- directly to ground. This results in Figure 2 There is still a problem with this application, that is, the wiring is complicated and easy to make mistakes, which may burn the LED lamp beads. Summary of the invention

[0004] The present invention aims to provide an adaptive buck-boost driving circuit, driving method and automobile lamp, in order to solve the technical problem that when a boost circuit is used in the prior art to realize the buck-boost function, manual wiring needs to be performed according to the load conditions, resulting in complex manual wiring and easy connection errors.

[0005] In order to solve the above technical problems, the first aspect of the present invention provides an adaptive buck-boost driving circuit, the adaptive buck-boost driving circuit includes a main control, a Boost circuit and a load, the positive electrode of the load is connected to the positive output end of the Boost circuit;

[0006] The adaptive buck-boost driving circuit further includes:

[0007] A first switch tube, wherein a drain of the first switch tube is connected to a negative electrode of the load, a source of the first switch tube is grounded, and a gate of the first switch tube is connected to the main control;

[0008] A first diode, wherein an anode of the first diode is connected to a drain of the first switch tube, and a cathode of the first diode is connected to a power supply terminal of the Boost circuit.

[0009] Optionally, in the adaptive buck-boost driving circuit as described above, the first switch tube is an NMOS tube.

[0010] Optionally, in the adaptive buck-boost driving circuit as described above, the first switch tube is an enhancement type NMOS tube.

[0011] Optionally, in the adaptive buck-boost driving circuit as described above, the load is an LED lamp.

[0012] Optionally, in the adaptive buck-boost driving circuit as described above, the adaptive buck-boost driving circuit further includes:

[0013] A voltage acquisition circuit is configured to acquire the voltage at the positive terminal of the load, and the output end of the voltage acquisition circuit is connected to the main control.

[0014] Optionally, in the adaptive buck-boost driving circuit as described above, the Boost circuit includes:

[0015] An energy storage inductor, one end of which is connected to the power supply end;

[0016] a second diode, wherein a cathode of the second diode is connected to an anode of the load;

[0017] A filter capacitor, wherein the positive electrode of the filter capacitor is connected to the negative electrode of the second diode, and the negative electrode of the filter capacitor is grounded;

[0018] A second switch tube, wherein the drain of the second switch tube is respectively connected to the other end of the energy storage inductor and the anode of the second diode, the source of the second switch tube is grounded, and the gate of the second switch tube is connected to the main control.

[0019] In order to solve the above technical problems, the second aspect of the present invention provides an adaptive buck-boost driving method for driving the adaptive buck-boost driving circuit provided by the first aspect of the present invention, and the adaptive buck-boost driving method includes:

[0020] After power-on, the main control controls the first switch tube to be turned off, so that the adaptive buck-boost driving circuit works in a buck-boost state;

[0021] The main control collects the positive terminal voltage value of the load. If the voltage value is greater than a preset value, the first switch tube is controlled to be turned on so that the adaptive buck-boost drive circuit operates in a boost state. If the voltage value is not greater than the preset value, the first switch tube is kept in an off state.

[0022] Optionally, in the adaptive buck-boost driving method as described above, the preset value is:

[0023] 2Vin+N

[0024] Wherein, Vin is the voltage input to the power supply end of the Boost circuit, and N is a preset driving switching voltage value.

[0025] Optionally, in the adaptive buck-boost driving method as described above, when the load is an LED lamp, N≥6V.

[0026] In order to solve the aforementioned technical problem, a third aspect of the present invention provides an automobile lamp, wherein the automobile lamp has the adaptive buck-boost driving circuit provided by the first aspect of the present invention.

[0027] The positive improvement effect of the present invention is that compared with the traditional solution such as Figure 2Compared with the Boost circuit in the prior art which can only work in the buck-boost state, the present invention can automatically switch the circuit to the boost state or the buck-boost state according to the connected load condition, giving full play to the boost characteristic of the Boost circuit, optimizing the power supply efficiency, and no need to confirm the load connection condition during wiring, thus simplifying the workers' wiring method and improving the yield rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The disclosure of the present invention will become more apparent with reference to the accompanying drawings. It should be understood that these drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present invention. In the drawings:

[0029] Figure 1 A schematic diagram of a circuit using a 4-switch Buck-Boost circuit in the prior art to achieve a step-up and step-down function;

[0030] Figure 2 A schematic diagram of a circuit using a Boost circuit to achieve a voltage step-up and voltage step-down function in the prior art;

[0031] Figure 3 A basic circuit diagram of a Boost circuit in the prior art;

[0032] Figure 4 A circuit diagram of the present invention;

[0033] Figure 5 Another circuit diagram of the present invention is shown in FIG. DETAILED DESCRIPTION

[0034] The following describes the embodiments of the present invention through 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.

[0035] It should be noted that the following embodiments and features therein may be combined with each other if there is no conflict.

[0036] In the description of the present invention, it should be noted that directional words such as the terms "outside", "middle", "inside", "outside", etc., which indicate directions and positional relationships, are based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and cannot be understood as limiting the specific protection scope of the present invention.

[0037] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. Therefore, the definition of "first" and "second" features can explicitly or implicitly include one or more of the features. In the description of the present invention, "several" and "a number" mean two or more, unless otherwise clearly and specifically defined.

[0038] Reference Figure 4 and Figure 5 An embodiment of the present invention provides an adaptive buck-boost driving circuit, which includes a main control, a Boost circuit, a load, a first switch tube Q1' and a first diode D1'.

[0039] In the basic topology of the traditional Boost circuit, the main control is connected to the switch tube in the Boost circuit to control the switch tube in the Boost circuit to turn on or off. The positive electrode of the load is connected to the positive output end of the Boost circuit, and the negative electrode of the load is grounded. In the present invention, the positive electrode of the load is connected to the positive output end of the Boost circuit, and the negative electrode of the load is not grounded, so as to realize the automatic switching of the boost state and the buck-boost state of the entire circuit.

[0040] In the existing driving circuit, an MCU main control is usually used to control the Boost circuit. The main control of the present invention shares the MCU main control, so as to realize the automatic switching function between the boost state and the buck-boost state without increasing the circuit cost.

[0041] The drain of the first switch tube Q1' is connected to the negative electrode of the load, the source of the first switch tube Q1' is grounded, and the gate of the first switch tube Q1' is connected to the main control. The anode of the first diode D1' is connected to the drain of the first switch tube Q1', and the cathode of the first diode D1' is connected to the power supply terminal Vin of the Boost circuit.

[0042] The present invention adds a first switch tube Q1' and a first diode D1' to the traditional Boost circuit. When the first switch tube Q1' is controlled to be turned on, the first diode D1' is subjected to a reverse voltage and is cut off, and the Boost circuit works in a boost state; when the first switch tube Q1' is controlled to be turned off, the Boost circuit works in a buck-boost state, and the current of the load flows to the power supply terminal Vin through the first diode D1'.

[0043] In some embodiments, the first switch tube Q1 ′ is an NMOS tube.

[0044] In some embodiments, the first switch tube Q1 ′ is an enhancement type NMOS tube.

[0045] In some embodiments, the load is an LED lamp.

[0046] like Figure 4 and Figure 5 As shown in , the positive electrode of the LED lamp is connected to the positive output terminal of the Boost circuit, and the negative electrode of the LED lamp is connected to the drain of the first switch tube Q1 '.

[0047] In this embodiment, when the first switch tube Q1' is controlled to be turned on, the first diode D1' is subjected to a reverse voltage and is cut off. At this time, the Boost circuit operates in a boost state, which is suitable for driving LED lamps with more than 6 strings of lamp beads; when the first switch tube Q1' is controlled to be turned off, the Boost circuit operates in a boost-boost state, and the current of the LED lamp flows to the power supply terminal Vin through the first diode D1', which is suitable for driving LED lamps with less than 6 strings of lamp beads.

[0048] Of course, the load of the present invention may also be other loads that need to realize automatic switching between a boost state and a buck-boost state.

[0049] In some embodiments, the adaptive buck-boost driving circuit further includes a voltage acquisition circuit, which is used to acquire the voltage at the positive terminal of the load, and the output end of the voltage acquisition circuit is connected to the main control.

[0050] The voltage collection circuit in this embodiment can directly adopt any circuit in the prior art that can realize voltage collection, for example, adopting a sampling resistor to collect the voltage at the positive terminal of the load.

[0051] The output end of the voltage acquisition circuit is connected to the ADC sampling end of the main control, and the main control can obtain the voltage value of the positive end of the load.

[0052] In some embodiments, reference Figure 3 and Figure 4 The boost circuit 1 is a step-up boost circuit, and the boost circuit 1 includes an energy storage inductor L', a second diode D2', a filter capacitor C' and a second switch tube Q2'.

[0053] One end of the energy storage inductor L' is connected to the power supply terminal Vin, and the other end of the energy storage inductor L' is respectively connected to the drain of the second switch tube Q2' and the anode of the second diode D2'.

[0054] The anode of the second diode D2' is connected to the other end of the energy storage inductor L' and the drain of the second switch tube Q2' respectively, and the cathode of the second diode D2' is connected to the anode of the load, that is, the cathode end of the second diode D2' is the positive output end of the Boost circuit.

[0055] The positive electrode of the filter capacitor C' is connected to the negative electrode of the second diode D2', and the negative electrode of the filter capacitor C' is grounded.

[0056] The drain of the second switch tube Q2' is respectively connected to the other end of the energy storage inductor L' and the anode of the second diode D2', the source of the second switch tube Q2' is grounded, and the gate of the second switch tube Q2' is connected to the main control, which controls the second switch tube Q2' to be turned on or off.

[0057] The working principle of the Boost circuit 1 is as follows: when the second switch tube Q2' is controlled to be turned on, the second diode D2' is turned off, and the voltage input by the power supply terminal Vin directly returns after passing through the energy storage inductor L', causing the current passing through the energy storage inductor L' to increase linearly, and at this time, the filter capacitor C' discharges to the load. When the second switch tube Q2' is controlled to be turned off, since the current of the energy storage inductor L' cannot change suddenly in an instant, a reverse electromotive force Vl will be generated on the energy storage inductor L' to maintain the current unchanged. At this time, the second diode D2' is turned on, and the voltage (Vin+Vl) exceeding the input of the power supply terminal Vin is supplied to the load, and the filter capacitor C' is charged. At this time, the Boost circuit 1 is in a boost state.

[0058] In this embodiment, the Boost circuit 1 is a basic circuit structure. Of course, other circuits based on Figure 3 The voltage-boosting Boost circuits with modified structures of this basic circuit are all applicable to the present invention.

[0059] For example, refer to Figure 5 , is the application of the present invention in a two-phase interleaved Boost circuit, which is based on Figure 3 The modified structure of Boost circuit 1, with Figure 3 Compared with the Boost circuit 1 of the present invention, the two-phase interleaved Boost circuit has an energy storage inductor L', a second diode D2', a filter capacitor C' and a second switch tube Q2' in addition to the energy storage inductor L', the second diode D2', the filter capacitor C' and the second switch tube Q2' of the Boost circuit 1, and an additional third energy storage inductor L3', a third diode D3' and a third switch tube Q3'. The circuit connection mode of each component is the same as the circuit connection mode of the energy storage inductor L', the second diode D2' and the second switch tube Q2' of the Boost circuit 1, that is:

[0060] One end of the third energy storage inductor L3' is connected to the power supply terminal Vin, and the other end of the third energy storage inductor L3' is respectively connected to the drain of the third switch tube Q3' and the anode of the third diode D3'.

[0061] The anode of the third diode D3' is connected to the other end of the third energy storage inductor L3' and the drain of the third switch tube Q3' respectively, and the cathode of the third diode D3' is connected to the anode of the load, that is, the cathode end of the third diode D3' is also the positive output end of the two-phase interleaved Boost circuit.

[0062] The positive electrode of the filter capacitor C' is connected to the negative electrode of the third diode D3', and the negative electrode of the filter capacitor C' is grounded.

[0063] The drain of the third switch tube Q3' is respectively connected to the other end of the third energy storage inductor L3' and the anode of the third diode D3', the source of the third switch tube Q3' is grounded, and the gate of the third switch tube Q3' is connected to the main control, which controls the switching on or off of the third switch tube Q3'.

[0064] The embodiment of the present invention further provides an adaptive buck-boost driving method, which is used to drive the adaptive buck-boost driving circuit provided by the above embodiments of the present invention. The adaptive buck-boost driving method includes:

[0065] After power-on, the main control controls the first switch tube Q1' to turn off, so that the adaptive buck-boost driving circuit works in the buck-boost state. The main control collects the positive terminal voltage value of the load. If the voltage value is greater than the preset value, the first switch tube Q1' is controlled to be turned on, so that the adaptive buck-boost driving circuit works in the boost state. If the voltage value is not greater than the preset value, the first switch tube Q1' is kept in the off state.

[0066] The driving method of the present invention can collect and judge the voltage value once after power-on, so as to make adaptive adjustment according to the connected load condition.

[0067] The preset value in the present invention can be preset to different preset values ​​according to different connected loads.

[0068] In some embodiments, the preset value is:

[0069] 2Vin+N

[0070] Wherein, Vin is the voltage value input to the power supply end of the Boost circuit, and N is the preset driving switching voltage value.

[0071] In this embodiment, N needs to satisfy the requirement of not less than the voltage value of the output voltage being higher than the input voltage, that is, N is greater than or equal to the voltage difference between the output voltage and the input voltage. Therefore, the driving switching voltage value is determined according to the connected load condition, and it can be a preset natural number or decimal.

[0072] In some embodiments, when the load is an LED lamp, N≥6V.

[0073] In this embodiment, when applied to automotive lamps, the voltage of the LED lamp is usually 3V, and the voltage value of the input power supply terminal Vin is usually 12V. Taking 6 strings of LED lamps as the boundary, 6 strings of LED lamps are 18V, which is 6V higher than the input voltage of 12V, so N is set to be not less than 6V, and when the boost condition is met, the circuit can work in the boost state.

[0074] An embodiment of the present invention further provides an automobile lamp, which has the adaptive buck-boost driving circuit provided by the above embodiments of the present invention.

[0075] Embodiment 1:

[0076] The adaptive buck-boost driving circuit is used to drive the car lights, and the car lights are connected to the adaptive buck-boost driving circuit as loads. Figure 4 , connect the positive pole of the car light to LED+, and connect the negative pole of the car light to LED-. The wiring is simple.

[0077] The driver board of the car lamp usually contains an MCU main controller, and the adaptive buck-boost drive circuit can directly share the MCU main controller without increasing the circuit cost.

[0078] After power-on, the MCU main control controls the first switch tube Q1' to turn off, and the control of the Boost circuit, especially the control of the second switch tube Q2', adopts the existing technology to make the whole circuit work in the buck-boost state.

[0079] The voltage V(LED+) at the LED+ end is collected through the ADC of the MCU main control. If the number of LED lamps in series is relatively large and V(LED+)-Vin>Vin+6, that is, V(LED+)>2Vin+6, the MCU main control controls the first switch tube Q1' to be turned on, and the control of the Boost circuit adopts the existing technology to make the whole circuit work in the boost state, which will improve the efficiency of the whole circuit; if the number of LED lamps in series is relatively small and V(LED+)≤2Vin+6 is satisfied, the MOS tube Q2 is kept in the off state.

[0080] The control of the Boost circuit may be carried out by using existing technologies such as peak current mode control and / or voltage mode control.

[0081] The present invention is described in detail above in conjunction with the embodiments of the accompanying drawings. A person skilled in the art can make various variations of the present invention according to the above description. Therefore, some details in the embodiments should not be construed as limiting the present invention, and the present invention shall be protected by the scope defined by the attached claims.

Claims

1. An adaptive buck-boost driving circuit, comprising a main control, a Boost circuit and a load, characterized in that: The positive electrode of the load is connected to the positive output terminal of the Boost circuit; The adaptive buck-boost driving circuit further includes: A first switch tube, wherein a drain of the first switch tube is connected to a negative electrode of the load, a source of the first switch tube is grounded, and a gate of the first switch tube is connected to the main control; A first diode, wherein an anode of the first diode is connected to a drain of the first switch tube, and a cathode of the first diode is connected to a power supply terminal of the Boost circuit.

2. The adaptive buck-boost driving circuit according to claim 1, characterized in that: The first switch tube is an NMOS tube.

3. The adaptive buck-boost driving circuit according to claim 2, characterized in that: The first switch tube is an enhanced NMOS tube.

4. The adaptive buck-boost driving circuit according to claim 1, wherein: The load is an LED lamp.

5. The adaptive buck-boost driving circuit according to claim 1, characterized in that: The adaptive buck-boost driving circuit further includes: A voltage acquisition circuit is configured to acquire the voltage at the positive terminal of the load, and the output end of the voltage acquisition circuit is connected to the main control.

6. The adaptive buck-boost driving circuit according to claim 1, characterized in that: The Boost circuit comprises: An energy storage inductor, one end of which is connected to the power supply end; a second diode, wherein a cathode of the second diode is connected to an anode of the load; A filter capacitor, wherein the positive electrode of the filter capacitor is connected to the negative electrode of the second diode, and the negative electrode of the filter capacitor is grounded; A second switch tube, wherein the drain of the second switch tube is respectively connected to the other end of the energy storage inductor and the anode of the second diode, the source of the second switch tube is grounded, and the gate of the second switch tube is connected to the main control.

7. An adaptive buck-boost driving method, characterized in that: The adaptive buck-boost driving method is used to drive the adaptive buck-boost driving circuit according to any one of claims 1 to 6, and the adaptive buck-boost driving method comprises: After power-on, the main control controls the first switch tube to be turned off, so that the adaptive buck-boost driving circuit works in a buck-boost state; The main control collects the positive terminal voltage value of the load. If the voltage value is greater than a preset value, the first switch tube is controlled to be turned on so that the adaptive buck-boost drive circuit operates in a boost state. If the voltage value is not greater than the preset value, the first switch tube is kept in an off state.

8. The adaptive buck-boost driving method according to claim 7, wherein: The preset values ​​are: 2Vin+N Wherein, Vin is the voltage input to the power supply end of the Boost circuit, and N is a preset driving switching voltage value.

9. The adaptive buck-boost driving method according to claim 8, wherein: When the load is an LED lamp, N≥6V.

10. An automobile lamp, characterized in that: The automobile lamp has the adaptive buck-boost driving circuit according to any one of claims 1 to 6.

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