An automatic power supply control circuit and method based on a vehicle-mounted 24V system

Abstract

This invention discloses an automatic power supply control circuit based on a vehicle 24V system, comprising an ignition signal circuit, an enable control circuit, and a DC-DC step-down circuit. The power input terminal of the ignition signal circuit is electrically connected to the positive terminal of the vehicle 24V power supply, the level signal output terminal of the ignition signal circuit is electrically connected to the second input terminal of the enable control circuit, the first input terminal of the enable control circuit is electrically connected to the positive terminal of the vehicle 24V power supply, the input terminal of the DC-DC step-down circuit is electrically connected to the positive terminal of the vehicle 24V power supply, the enable terminal of the DC-DC step-down circuit is electrically connected to the output terminal of the enable control circuit, and the output terminal of the DC-DC step-down circuit is electrically connected to the load circuit. This achieves automatic power-on and power-off regulation of the load circuit, ensuring that the vehicle battery is not depleted while also guaranteeing the normal operation of the load circuit.

Description

Technical Field

[0001] This invention relates to the field of automotive power technology, and in particular to an automatic power supply control circuit and method based on a vehicle 24V system. Background Technology

[0002] With advancements in the automotive industry, larger vehicles with higher compression ratios and larger engine displacements have emerged. Because of their higher compression ratios and greater friction coefficients, starting force is hindered, requiring high-voltage, high-current starters. Traditional 12V power systems are insufficient, necessitating the use of higher-voltage 24V systems. A 24V power supply uses two 12V batteries connected in series, achieving a maximum voltage of 32V and a minimum voltage potentially dropping below 9V. Due to the wide range of battery voltages and the dual states of ignition and shutdown in automobiles, the load circuit powered by the battery needs to switch between on / off states based on the real-time battery voltage and the vehicle's ignition status. Failure to automatically control this switching can lead to abnormal voltage in the load circuit, potentially causing battery leakage. Therefore, a low-cost automatic power supply control circuit is needed to ensure the vehicle battery doesn't run out of power while simultaneously guaranteeing the normal operation of the load circuit. Summary of the Invention

[0003] The main objective of this invention is to address the shortcomings of existing technologies that cannot automatically control the power-on and power-off states based on real-time conditions, leading to abnormal load circuit voltage and, in severe cases, leakage of the vehicle battery. This invention provides a low-cost automatic power supply control circuit and method based on a vehicle 24V system.

[0004] To achieve the above objectives, the present invention provides an automatic power supply control circuit based on a vehicle 24V system, used to automatically control the power supply of the load circuit according to the vehicle 24V power supply status and the vehicle ignition status. The circuit includes an ignition signal circuit, an enable control circuit, and a DC-DC step-down circuit. The power input terminal of the ignition signal circuit is electrically connected to the positive terminal of the vehicle 24V power supply. The level signal output terminal of the ignition signal circuit is electrically connected to the second input terminal of the enable control circuit. The first input terminal of the enable control circuit is electrically connected to the positive terminal of the vehicle 24V power supply. The input terminal of the DC-DC step-down circuit is electrically connected to the positive terminal of the vehicle 24V power supply. The enable terminal of the DC-DC step-down circuit is electrically connected to the output terminal of the enable control circuit. The output terminal of the DC-DC step-down circuit is electrically connected to the load circuit.

[0005] The enable control circuit outputs an enable control voltage based on the voltage values ​​of the first input terminal and the second input terminal, and the DC buck circuit controls the conduction and disconnection of the output terminal and the input terminal based on the enable control voltage value of the enable terminal.

[0006] Preferably, the enabling control circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a ground terminal, an NPN transistor, a PNP transistor, and a Zener diode. The cathode of the Zener diode serves as the first input terminal of the enabling control circuit and is electrically connected to the positive terminal of the vehicle's 24V power supply. The anode of the Zener diode is connected in series with the first resistor, the second resistor, the third resistor, and the ground terminal. The anode of the Zener diode is connected in series with the fourth resistor and the fifth resistor. The emitter of the PNP transistor is electrically connected to the anode of the Zener diode. The collector of the PNP transistor is connected to the second... The first end of the resistor is electrically connected, the second end of the second resistor is electrically connected to the enable terminal of the DC step-down circuit as the output terminal of the enable control circuit, the base of the PNP transistor is electrically connected to the first end of the fifth resistor, the second end of the fifth resistor is electrically connected to the collector of the NPN transistor, the emitter of the NPN transistor is electrically connected to the ground terminal, the base of the NPN transistor is electrically connected to the first end of the sixth resistor, the second end of the sixth resistor is electrically connected to the level signal output terminal of the ignition signal circuit as the second input terminal of the enable control circuit, and the second end of the sixth resistor is connected in series with the seventh resistor and the ground terminal.

[0007] Preferably, the DC-DC step-down circuit includes a DC-DC converter chip, the input terminal of which is electrically connected to the positive terminal of the vehicle's 24V power supply, the output terminal of which is electrically connected to the load circuit to supply power to the load circuit, the enable terminal of which is electrically connected to the output terminal of the enable control circuit, and the output voltage of which is 5V.

[0008] Preferably, the first resistor has a resistance of 1.07 MΩ, the second resistor has a resistance of 220 KΩ, the third and fifth resistors have a resistance of 100 KΩ, the fourth resistor has a resistance of 499 KΩ, the sixth resistor has a resistance of 150 KΩ, the seventh resistor has a resistance of 10 KΩ, and the voltage drop of the Zener diode is 5.1 V.

[0009] Preferably, the vehicle-mounted 24V power supply includes two 12V batteries, which are connected in series to supply power to the outside.

[0010] Furthermore, to achieve the above objectives, the present invention also provides an automatic power supply control method based on a vehicle 24V system. This method is an automatic power supply control method for the aforementioned automatic power supply control circuit, used to automatically control the power supply to the load circuit based on the vehicle 24V power supply status and the vehicle ignition status, including...

[0011] Step S100: Detect the vehicle's 24V power supply voltage and the vehicle's ignition signal level;

[0012] Step S200: Input the detected value, and output an enable voltage signal that is selectively calculated and correlated with the detected value;

[0013] Step S300: Determine whether the enable voltage signal value exceeds the critical voltage value, and then control the load circuit to be powered on or off.

[0014] Preferably, step S200 includes: inputting the vehicle 24V power supply voltage value to the first input terminal of the enable control circuit, and inputting the vehicle ignition signal level value to the second input terminal of the enable control circuit; when the vehicle ignition signal level is low, an enable voltage signal is output according to the formula Ven=(VCC-VD1)*R3 / (R1+R2+R3); when the vehicle ignition signal level is high, an enable voltage signal is output according to the formula Ven=(VCC-VD1)*R3 / (R2+R3); where Ven is the enable voltage signal value, VCC is the vehicle 24V power supply voltage value, VD1 is the voltage drop of the Zener diode, R1 is the first resistor value, R2 is the second resistor value, and R3 is the third resistor value.

[0015] Preferably, step S300 includes: detecting the enable voltage signal voltage value, comparing the enable voltage signal voltage value with a critical voltage value; when the enable voltage signal voltage value is higher than the critical voltage value, the vehicle 24V power supply and the load circuit are connected and powered on; when the enable voltage signal voltage value is lower than the critical voltage value, the vehicle 24V power supply and the load circuit are disconnected and powered off.

[0016] Preferably, in step S200, the voltage drop of the Zener diode is 5.1V with an error of ±0.3V, the resistance of the first resistor is 1.07MΩ with an error of ±1%, the resistance of the second resistor is 220KΩ with an error of ±1%, and the resistance of the third resistor is 100KΩ with an error of ±1%.

[0017] Preferably, the critical voltage value in step S300 is 1.2V.

[0018] The automatic power supply control circuit and method based on a vehicle 24V system provided by this invention have the following advantages: By employing an automatic control circuit composed of discrete components such as a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an NPN transistor, a PNP transistor, and a Zener diode, the automatic power-on and power-off regulation of the load circuit is achieved based on the voltage value of the vehicle 24V power supply and the ignition signal level. The automatic control circuit has low implementation cost and saves space on the internal circuit board. The power consumption of this automatic control circuit is low; when powered by a 24V vehicle 24V power supply, its maximum leakage current is 66uA. It does not occupy any MCU or other processor's I / O, ADC, or other resources, and is completely automatically controlled by external signals. On the one hand, this reduces the risk of system instability caused by program control, and on the other hand, it reduces the overall automotive system's project resources. This automatic control circuit has a Zener diode, so when the voltage of the vehicle's 24V power supply and the ignition signal level are below 5.1V, the automotive system will not experience the risk of leakage due to malfunction. At the same time, because the Zener diode and the resistance values ​​of each resistor in this circuit can be adjusted according to requirements, it can also be used with 12V or 48V power supply systems, and has extremely strong scalability, thus adapting to various control and device requirements. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort:

[0020] Figure 1 The diagram shown is a circuit schematic of an automatic power supply control circuit based on a vehicle 24V system according to an embodiment of the present invention.

[0021] Figure 2 The diagram shown is a flowchart illustrating an automatic power supply control method based on a vehicle-mounted 24V system according to an embodiment of the present invention.

[0022] 10. Vehicle 24V power supply; 20. Ignition signal circuit; 30. Load circuit; 40. DC step-down circuit; 50. Enable control circuit; R1. First resistor; R2. Second resistor; R3. Third resistor; R4. Fourth resistor; R5. Fifth resistor; R6. Sixth resistor; R7. Seventh resistor; D1. Zener diode; Q1. PNP transistor; Q2. NPN transistor; U1. DC to DC step-down converter chip; GND. Ground terminal; S100. Step S100; S200. Step S200; S300. Step S300. Detailed Implementation

[0023] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Typical embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0025] The general idea of ​​this invention is to address the shortcomings of existing technologies that cannot automatically control the power on / off state based on real-time conditions, leading to abnormal load circuit voltage and, in severe cases, leakage of the vehicle battery. This invention provides an automatic power supply control circuit and method based on a vehicle 24V system, which has the following advantages: By employing an automatic control circuit composed of discrete components such as a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an NPN transistor, a PNP transistor, and a Zener diode, the automatic power on / off regulation of the load circuit is achieved based on the voltage value of the vehicle 24V power supply and the ignition signal level. The automatic control circuit has low implementation cost and saves space on the internal circuit board; the power consumption of this automatic control circuit is low, making it suitable for use in vehicle systems. When powered by a 24V power supply, its maximum leakage current is 66uA. This control circuit does not occupy any MCU or other processor's I / O, ADC, or other resources, and is completely automatically controlled by external signals. On the one hand, this reduces the risk of system instability caused by program control, and on the other hand, it reduces the overall automotive system's project resources. This automatic control circuit has a Zener diode, so when the voltage of the onboard 24V power supply and the ignition signal level are below 5.1V, the automotive system will not experience the risk of leakage due to malfunction. At the same time, because the Zener diode and the resistance values ​​of each resistor in this circuit can be adjusted according to requirements, it can also be used with 12V or 48V power supply systems, and has extremely strong scalability, thus adaptable to various control and device requirements.

[0026] To better understand the above technical solutions, the following will describe the above technical solutions in detail with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solutions of this application, rather than limitations on the technical solutions of this application. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0027] Reference Figure 1 , Figure 1 The diagram shows a circuit diagram of an automatic power supply control circuit based on a vehicle 24V system according to the present invention. In this embodiment, the automatic power supply control circuit includes an ignition signal circuit 20, an enable control circuit 50, and a DC step-down circuit 40. The power input terminal of the ignition signal circuit is electrically connected to the positive terminal of the vehicle 24V power supply 10. The level signal output terminal of the ignition signal circuit is electrically connected to the second input terminal of the enable control circuit. The first input terminal of the enable control circuit is electrically connected to the positive terminal of the vehicle 24V power supply. The input terminal of the DC step-down circuit is electrically connected to the positive terminal of the vehicle 24V power supply. The enable terminal of the DC step-down circuit is electrically connected to the output terminal of the enable control circuit. The output terminal of the DC step-down circuit is electrically connected to the load circuit 30. The enable control circuit outputs an enable control voltage according to the voltage values ​​of the first and second input terminals. The DC step-down circuit controls the conduction and disconnection of the output terminal and the input terminal according to the enable control voltage value of the enable terminal.

[0028] The automatic power supply control circuit controls the energization and de-energization of the load circuit 30 and the vehicle's 24V power supply 10. It controls the connection and disconnection of the line between the load circuit and the vehicle's 24V power supply based on the voltage state of the vehicle's 24V power supply and the vehicle's operating state. The vehicle's operating state is the ignition state, i.e., ignition and shutdown. The ignition signal circuit outputs an ignition signal based on the ignition state of the vehicle's ignition system. Typically, the vehicle's ignition system has two positions: ignition and shutdown, meaning the ignition signal has two levels: high and low. When in the ignition state, the power input terminal and the level signal output terminal of the ignition signal circuit are connected, and the voltage at the level signal output terminal is the same as the power input terminal voltage. The power input terminal is electrically connected to the vehicle's 24V power supply; that is, the power at the level signal output terminal is the same as the vehicle's 24V power supply voltage when in the ignition state. When in the shutdown state, the power input terminal and the level signal output terminal of the ignition signal circuit are disconnected; that is, there is no voltage at the level signal output terminal when in the shutdown state. The main components of a car ignition system include a 24V power supply or generator, ignition coil, distributor, ignition switch, spark plugs, and related control circuits. The ignition switch is an electrical control device that connects and disconnects the attraction coil and the holding coil circuit.

[0029] The vehicle's 24V power supply is specifically composed of two 12V batteries connected in series to supply power to various load circuits. When the two 12V batteries are fully charged, their maximum voltage can reach 32V, while when they are depleted, the voltage can drop to below 9V. Therefore, the voltage range of the vehicle's 24V power supply is relatively wide. Since the load circuits are powered by the batteries, the switching mode of the load circuits needs to be switched according to different battery voltages and vehicle ignition status when the car is running and the engine is off.

[0030] The load circuit includes a TCU load circuit, which collects vehicle-related information, including position, attitude, and status information, via the vehicle's CAN bus. This information is then transmitted wirelessly to the TSP platform. Simultaneously, users can use a mobile app and web client to send commands to the TBOX terminal through the TSP platform to control the vehicle. Therefore, ensuring the load circuit's power supply and normal operation while the vehicle is running is crucial. Conversely, when the vehicle is off, it's essential to prevent the load circuit from draining the battery and causing overall vehicle power loss.

[0031] The enable control circuit, as the core control part of this power supply automatic control circuit, has two input terminals connected to the vehicle 24V power supply and the ignition signal level output terminal, respectively. It controls the power on and power off of the load circuit by detecting the vehicle 24V power supply voltage value and the ignition signal level output and calculating the enable control voltage signal that is selectively correlated with the vehicle 24V power supply voltage value and the ignition signal level.

[0032] The DC step-down circuit serves as the switching control part of this power supply automatic control circuit. Its input terminal is connected to the positive terminal of the vehicle's 24V power supply, and its output terminal is connected to the load circuit. The conduction and disconnection of the input and output terminals are controlled by the enable control voltage signal at its enable terminal. When the voltage value of the enable control signal output by the enable control circuit is greater than the critical voltage value of the DC step-down circuit, the input and output terminals are in a conducting state, and the vehicle's 24V power supply powers the load circuit. When the voltage value of the enable control signal output by the enable control circuit is less than the critical voltage value of the DC step-down circuit, the input and output terminals are in a disconnected state, and the vehicle's 24V power supply is not energized to the load circuit.

[0033] The enable control circuit can be composed of various components, requiring only two input terminals: one connected to the vehicle's 24V power supply and the other to the ignition signal level. It must also output an enable control voltage signal. The input-output relationship must satisfy the following: when the ignition signal level is high, the output enable control voltage signal is within a preset range; when the ignition signal level is low, the output enable control voltage signal is within another preset range. Furthermore, the enable control circuit should have as few components as possible, not occupying any MCU or other processor's I / O, ADC, or other resources. It should also be applicable to other 12V or 48V power supply systems with different thresholds, possessing strong scalability and adaptability to various DC buck control switches. Specifically, the enable control circuit includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a ground terminal GND, an NPN transistor Q2, a PNP transistor Q1, and a Zener diode D1. The cathode of the Zener diode D1 serves as the first input terminal of the enable control circuit and is electrically connected to the positive terminal of the vehicle's 24V power supply. The anode of the Zener diode D1 is connected in series with the first resistor R1, the second resistor R2, the third resistor R3, and the ground terminal GND. The anode of the Zener diode D1 is connected in series with the fourth resistor R4 and the fifth resistor R5. The emitter of the PNP transistor Q1 is electrically connected to the anode of the Zener diode D1. The collector of transistor Q1 is electrically connected to the first end of the second resistor R2. The second end of the second resistor R2 serves as the output terminal of the enable control circuit and is electrically connected to the enable terminal of the DC-DC step-down circuit. The base of PNP transistor Q1 is electrically connected to the first end of the fifth resistor R5. The second end of the fifth resistor R5 is electrically connected to the collector of NPN transistor Q2. The emitter of NPN transistor Q2 is electrically connected to ground GND. The base of NPN transistor Q2 is electrically connected to the first end of the sixth resistor R6. The second end of the sixth resistor R6 serves as the second input terminal of the enable control circuit and is electrically connected to the level signal output terminal of the ignition signal circuit. The second end of the sixth resistor R6 is connected in series with the seventh resistor R7 and the ground GND. The ground terminal is generally connected to the common ground of the vehicle.

[0034] When the ignition signal level is low, the ignition signal voltage is divided by resistors R6 and R7, causing the NPN transistor to be in the cutoff region. At this time, the base and emitter voltages of the PNP transistor Q1 are equal, and the PNP transistor is also in the cutoff state. Resistors R1, R2, and R3 are connected in series in the circuit to form a voltage divider. The enable voltage signal is determined by the voltage drop across resistors R1, R2, R3, and Zener diode D1, i.e., Ven = (VCC - VD1) * R3 / (R1 + R2 + R3). In this formula, Ven is the enable voltage signal value, VCC is the 24V vehicle power supply voltage, VD1 is the Zener diode voltage drop, R1 is the resistance of the first resistor, R2 is the resistance of the second resistor, and R3 is the resistance of the third resistor. When the ignition signal level is high, the ignition signal voltage is divided by the sixth resistor R6 and the seventh resistor R7, and the NPN transistor Q2 is in the saturation region. At this time, the PNP transistor Q1 enters the saturation state under the voltage division of the fourth resistor R4 and the fifth resistor R5, and the PNP transistor Q1 is turned on. The first resistor R1 is turned off. The voltage of the enable voltage signal at this time is determined by the voltage drop of the second resistor R2, the third resistor R3 and the Zener diode D1, that is, Ven=(VCC-VD1)*R3 / (R2+R3).

[0035] For a DC-DC step-down circuit, it only needs to meet the requirement of DC-DC step-down and be able to control the conduction and disconnection of the DC power supply through a control signal. Specifically, the DC-DC step-down circuit includes a DC-DC converter chip U1. The input terminal of the DC-DC converter chip U1 is electrically connected to the positive terminal of the vehicle's 24V power supply. The output terminal of the DC-DC converter chip U1 is electrically connected to the load circuit to supply power to the load circuit. The enable terminal of the DC-DC converter chip U1 is electrically connected to the output terminal of the enable control circuit. The output voltage of the DC-DC converter chip U1 is 5V.

[0036] The system detects the enable voltage signal value and compares it with the critical voltage value. When the enable voltage signal value is higher than the critical voltage value, the vehicle's 24V power supply and the load circuit are connected and powered on, outputting 5V DC power. When the enable voltage signal value is lower than the critical voltage value, the vehicle's 24V power supply and the load circuit are disconnected and powered off.

[0037] Each model of DC-DC buck converter chip has a fixed threshold voltage value at its enable terminal. The DC-DC buck converter chip can be selected according to the enable control circuit, and different input response logic enable control circuits can be designed according to the fixed threshold voltage value of the DC-DC buck converter chip.

[0038] In the vehicle's 24V system, the 24V power supply ground is formed by two 12V batteries connected in series. When fully charged, these batteries can reach a maximum voltage of 32V, and when depleted, the voltage can drop to below 9V. To ensure the system doesn't lose power due to load circuit consumption after the car is turned off, this invention sets the load circuit to disconnect from the 24V power supply when the 24V voltage is below 22V, entering a shutdown mode. To ensure the load circuit operates normally while the car is running, providing better information support, this invention sets the load circuit to be energized when the 24V voltage is above 9V, entering an energized mode. The shutdown voltage of 22V in the off state and the energizing voltage of 9V in the ignition state are empirical values ​​used in automotive design and can be changed according to actual needs. Furthermore, based on existing selected chips, the enable voltage of the DC-DC buck converter chip is 1.2V.

[0039] The following examples, using the set shutdown voltage of 22V in the off state and the power-on voltage of 9V in the ignition state, and the enable terminal threshold voltage of 1.2V, further explain the parameters of each component in the enable control circuit and the DC buck circuit.

[0040] Specifically, the first resistor R1 has a resistance of 1.07MΩ, the second resistor R2 has a resistance of 220KΩ, the third resistor R3 and the fifth resistor R5 have a resistance of 100KΩ, the fourth resistor R4 has a resistance of 499KΩ, the sixth resistor R6 has a resistance of 150KΩ, the seventh resistor R7 has a resistance of 10KΩ, and the voltage drop of the Zener diode D1 is 5.1V.

[0041] When the ignition signal is low, the enable control voltage is calculated according to the formula Ven=(VCC-VD1)*R3 / (R1+R2+R3). When the vehicle 24V power supply voltage VCC is 21.78V, the enable control voltage signal value Ven is 1.2V. That is, when the vehicle 24V power supply voltage VCC is greater than 21.78V, the enable control voltage signal value is higher than the critical voltage value, the output terminal of the DC-DC buck converter chip is connected to the input terminal, and the load circuit is powered by the vehicle 24V power supply. That is, when the vehicle 24V power supply voltage VCC is not greater than 21.78V, the enable control voltage signal value is not higher than the critical voltage value, the output terminal of the DC-DC buck converter chip is disconnected from the input terminal, and the load circuit is not powered by the vehicle 24V power supply.

[0042] When the ignition signal is high, the enable control voltage is calculated according to the formula Ven = (VCC - VD1) * R3 / (R2 + R3). When the vehicle 24V power supply voltage VCC is 8.94V, the enable control voltage signal value Ven is 1.2V. That is, when the vehicle 24V power supply voltage VCC is greater than 8.94V, the enable control voltage signal value is higher than the critical voltage value, the output terminal of the DC-DC step-down chip is connected to the input terminal, and the load circuit is powered by the vehicle 24V power supply. That is, when the vehicle 24V power supply voltage VCC is not greater than 8.94V, the enable control voltage signal value is not higher than the critical voltage value, the output terminal of the DC-DC step-down chip is disconnected from the input terminal, and the load circuit is not powered by the vehicle 24V power supply.

[0043] The errors in the above calculation formulas are mainly determined by the resistance values ​​of the first resistor R1, the second resistor R2, and the third resistor R3, and the voltage drop of the Zener diode D1. Specifically, the resistance value error of the first resistor R1, the second resistor R2, and the third resistor R3 is ±1%, and the voltage drop error of the Zener diode D1 is ±0.3V. After the car is turned off, the system requires a critical voltage of 22V, and the current calculated values ​​are 20.82V-22.73V. After the car is started, the system requires a critical voltage of 9V, and the current calculated values ​​are 8.37V-9.51V. The errors all meet the system's ±2V requirement.

[0044] Accordingly, the present invention also provides a control method for the above-mentioned automatic power supply control circuit, used to automatically control the power supply of the load circuit according to the power status of the vehicle's 24V power supply and the vehicle's ignition status, referring to... Figure 2 , Figure 2 The diagram shown is a flowchart of an automatic power supply control method based on a vehicle 24V system according to an embodiment of the present invention.

[0045] An automatic power supply control method based on a vehicle 24V system, including

[0046] Step S100: Detect the vehicle's 24V power supply voltage and the vehicle's ignition signal level;

[0047] Step S200: Input the detected value, and output an enable voltage signal that is selectively calculated and correlated with the detected value;

[0048] Step S300: Determine whether the enable voltage signal value exceeds the critical voltage value, and then control the load circuit to be powered on or off.

[0049] Preferably, step S200 includes: inputting the vehicle 24V power supply voltage value to the first input terminal of the enable control circuit, and inputting the vehicle ignition signal level value to the second input terminal of the enable control circuit; when the vehicle ignition signal level is low, outputting an enable voltage signal according to the formula Ven=(VCC-VD1)*R3 / (R1+R2+R3); when the vehicle ignition signal level is high, outputting an enable voltage signal according to the formula...

[0050] Ven = (VCC - VD1) * R3 / (R2 + R3), which is the output enable voltage signal; where Ven is the enable voltage signal value, VCC is the vehicle 24V power supply voltage value, VD1 is the voltage drop of the Zener diode D1, R1 is the first resistor value, R2 is the second resistor value, and R3 is the third resistor value.

[0051] Preferably, step S300 includes: detecting the enable voltage signal voltage value, comparing the enable voltage signal voltage value with a critical voltage value; when the enable voltage signal voltage value is higher than the critical voltage value, the vehicle 24V power supply and the load circuit are connected and powered on; when the enable voltage signal voltage value is lower than the critical voltage value, the vehicle 24V power supply and the load circuit are disconnected and powered off.

[0052] Preferably, in step S200, the voltage drop of the Zener diode D1 is 5.1V with an error of ±0.3V, the resistance of the first resistor R1 is 1.07MΩ with an error of ±1%, the resistance of the second resistor R2 is 220KΩ with an error of ±1%, and the resistance of the third resistor R3 is 100KΩ with an error of ±1%.

[0053] Preferably, the critical voltage value in step S300 is 1.2V.

[0054] This invention employs an automatic control circuit composed of discrete components such as resistors R1, R2, R3, R4, R5, R6, R7, an NPN transistor Q2, a PNP transistor Q1, and a Zener diode D1. This circuit automatically adjusts the power supply to and from the load circuit based on the vehicle's 24V power supply voltage and the ignition signal level. The automatic control circuit has low implementation cost and saves space on the internal circuit board. Furthermore, the power consumption of this automatic control circuit is low; when powered by a 24V vehicle power supply, its maximum leakage current is only 66uA. This control circuit does not occupy any MCU (Microcontroller Unit). The I / O, ADC, and other resources of other processors are completely automatically controlled by external signals. This reduces the risk of system instability caused by program control and also reduces the overall automotive system's resource requirements. The automatic control circuit has a Zener diode, which prevents the automotive system from malfunctioning and leaking current when the voltage of the vehicle's 24V power supply and the ignition signal level are below 5.1V. Furthermore, because the Zener diode and the resistance values ​​of various resistors in the circuit can be adjusted as needed, it can also be used with 12V or 48V power supply systems, exhibiting strong scalability and thus adaptable to various control and device requirements.

[0055] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0056] Similarly, it should be understood that, in order to simplify this disclosure and aid in understanding one or more of the various aspects of the invention, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof. However, this method of disclosure should not be construed as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the following claims, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into this detailed description, wherein each claim itself is a separate embodiment of the invention.

[0057] Those skilled in the art will understand that modules in the device of the embodiments can be adaptively changed and placed in one or more devices different from that embodiment. Modules, units, or components in the embodiments can be combined into a single module, unit, or component, and further, they can be divided into multiple sub-modules, sub-units, or sub-components. Except where at least some of such features and / or processes or units are mutually exclusive, any combination can be used to combine all features disclosed in this specification (including the accompanying claims, abstract, and drawings) and all processes or units of any method or device so disclosed. Unless expressly stated otherwise, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) may be replaced by an alternative feature that serves the same, equivalent, or similar purpose.

[0058] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of the invention and form different embodiments. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0059] The various component embodiments of the present invention can be implemented in hardware, or as software modules running on one or more processors, or a combination thereof. Those skilled in the art will understand that microprocessors or digital signal processors (DSPs) can be used in practice to implement some or all of the functions of some or all of the components according to the embodiments of the present invention. The present invention can also be implemented as a device or apparatus program (e.g., a computer program and computer program product) for performing part or all of the methods described herein. Such programs implementing the present invention can be stored on a computer-readable medium, or can be in the form of one or more signals. Such signals can be downloaded from an Internet website, provided on a carrier signal, or provided in any other form.

[0060] It should be noted that the above embodiments are illustrative of the invention and not restrictive, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names.

Claims

1. An automatic power supply control circuit based on a vehicle 24V system, used to automatically control the power supply of the load circuit according to the vehicle 24V power supply status and the vehicle ignition status, characterized in that: The automatic power supply control circuit includes an ignition signal circuit, an enable control circuit, and a DC-DC step-down circuit. The power input terminal of the ignition signal circuit is electrically connected to the positive terminal of the vehicle's 24V power supply. The level signal output terminal of the ignition signal circuit is electrically connected to the second input terminal of the enable control circuit. The first input terminal of the enable control circuit is electrically connected to the positive terminal of the vehicle's 24V power supply. The input terminal of the DC-DC step-down circuit is electrically connected to the positive terminal of the vehicle's 24V power supply. The enable terminal of the DC-DC step-down circuit is electrically connected to the output terminal of the enable control circuit. The output terminal of the DC-DC step-down circuit is electrically connected to the load circuit. The enable control circuit outputs an enable control voltage based on the voltage values ​​of the first input terminal and the second input terminal, and the DC buck circuit controls the conduction and disconnection of the output terminal and the input terminal based on the enable control voltage value of the enable terminal. The enabling control circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a ground terminal, an NPN transistor, a PNP transistor, and a Zener diode. The cathode of the Zener diode serves as the first input terminal of the enabling control circuit and is electrically connected to the positive terminal of the vehicle's 24V power supply. The anode of the Zener diode is connected in series with the first resistor, the second resistor, the third resistor, and the ground terminal in sequence. The anode of the Zener diode is also connected in series with the fourth resistor and the fifth resistor in sequence. The emitter of the PNP transistor is electrically connected to the anode of the Zener diode, and the collector of the PNP transistor is connected to the second resistor. The first terminal of the first resistor is electrically connected, the second terminal of the second resistor is electrically connected to the enable terminal of the DC step-down circuit as the output terminal of the enable control circuit, the base of the PNP transistor is electrically connected to the first terminal of the fifth resistor, the second terminal of the fifth resistor is electrically connected to the collector of the NPN transistor, the emitter of the NPN transistor is electrically connected to the ground terminal, the base of the NPN transistor is electrically connected to the first terminal of the sixth resistor, the second terminal of the sixth resistor is electrically connected to the level signal output terminal of the ignition signal circuit as the second input terminal of the enable control circuit, and the second terminal of the sixth resistor is connected in series with the seventh resistor and the ground terminal.

2. The automatic power supply control circuit based on the vehicle 24V system as described in claim 1, characterized in that: The DC-DC step-down circuit includes a DC-DC converter chip. The input terminal of the DC-DC converter chip is electrically connected to the positive terminal of the vehicle's 24V power supply. The output terminal of the DC-DC converter chip is electrically connected to the load circuit to supply power to the load circuit. The enable terminal of the DC-DC converter chip is electrically connected to the output terminal of the enable control circuit. The output voltage of the DC-DC converter chip is 5V.

3. The automatic power supply control circuit based on the vehicle 24V system as described in claim 2, characterized in that: The first resistor has a resistance of 1.07 MΩ, the second resistor has a resistance of 220 KΩ, the third and fifth resistors have a resistance of 100 KΩ, the fourth resistor has a resistance of 499 KΩ, the sixth resistor has a resistance of 150 KΩ, the seventh resistor has a resistance of 10 KΩ, and the voltage drop of the Zener diode is 5.1 V.

4. The automatic power supply control circuit based on a vehicle-mounted 24V system as described in any one of claims 1-3, characterized in that: The vehicle-mounted 24V power supply includes two 12V batteries, which are connected in series to supply power to the outside.

5. An automatic power supply control method based on a vehicle 24V system, used to automatically control the power supply of a load circuit according to the vehicle 24V power supply status and the vehicle ignition status, wherein the method is executed by the automatic power supply control circuit based on a vehicle 24V system as described in claim 1, characterized in that: include Step S100: Detect the vehicle's 24V power supply voltage and the vehicle's ignition signal level; Step S200: Input the detected value, and output an enable voltage signal that is selectively calculated and correlated with the detected value; Step S300: Determine whether the enable voltage signal value exceeds the critical voltage value, and then control the load circuit to be powered on or off. Step S200 includes: inputting the vehicle 24V power supply voltage value into the first input terminal of the enable control circuit, and inputting the vehicle ignition signal level value into the second input terminal of the enable control circuit; when the vehicle ignition signal level is low, an enable voltage signal is output according to the formula Ven=(VCC-VD1)*R3 / (R1+R2+R3). When the car ignition signal level is high, according to the formula Ven=(VCC-VD1)*R3 / (R2+R3), an enable voltage signal is output; where... In this formula, Ven is the enable voltage signal value, VCC is the vehicle 24V power supply voltage value, VD1 is the voltage drop of the Zener diode, R1 is the first resistor value, R2 is the second resistor value, and R3 is the third resistor value.

6. The automatic power supply control method based on a vehicle-mounted 24V system as described in claim 5, characterized in that: Step S300 includes: detecting the enable voltage signal voltage value, comparing the enable voltage signal voltage value with a critical voltage value; when the enable voltage signal voltage value is higher than the critical voltage value, the power supply line between the vehicle 24V power supply and the load circuit is connected; when the enable voltage signal voltage value is lower than the critical voltage value, the power supply line between the vehicle 24V power supply and the load circuit is disconnected.

7. The automatic power supply control method based on a vehicle-mounted 24V system as described in claim 5, characterized in that: In step S200, the voltage drop of the Zener diode is 5.1V with an error of ±0.3V, the resistance of the first resistor is 1.07MΩ with an error of ±1%, the resistance of the second resistor is 220KΩ with an error of ±1%, and the resistance of the third resistor is 100KΩ with an error of ±1%.

8. The automatic power supply control method based on a vehicle-mounted 24V system as described in claim 6, characterized in that: The critical voltage value in step S300 is 1.2V.

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