Cathode control circuit and method for commercial vehicle loading system

Abstract

The invention provides a negative electrode control circuit and method for a commercial vehicle loading system, the negative electrode control circuit is provided with a battery positive electrode interface, a battery negative electrode interface and an output interface, the battery positive electrode interface is connected with the positive electrode of a storage battery, the battery negative electrode interface is connected with the negative electrode of the storage battery, and the output interface is connected with the negative electrode of electric equipment; the negative electrode control circuit comprises a field effect transistor which is provided with a grid electrode, a drain electrode and a source electrode, the grid electrode is connected with the battery positive electrode interface, the drain electrode is connected with the output interface, and the source electrode is connected with the battery negative electrode interface; and the controller detects the voltage of the storage battery in real time, controls the switch-on and switch-off of the field effect transistor according to the voltage of the storage battery, and further controls the connection state of the output interface and the battery cathode interface. The technical problems that a lead-acid storage battery manager can only achieve the voltage and electric quantity detection function, a load switch cannot be directly controlled, and overdischarge cannot be fundamentally solved are solved.

Description

Technical Field

[0001] This invention relates to the field of electronic control technology, and more specifically, to a negative control circuit and a negative control method for a commercial vehicle superstructure system. Background Technology

[0002] As core equipment in logistics, public transportation and other fields, the stability of the low-voltage power supply system of commercial vehicles directly affects the vehicle's operating efficiency. Currently, commercial vehicles typically use 24V lead-acid batteries as low-voltage power sources to supply power to the entire vehicle and its superstructure after the vehicle is turned off. The superstructure of commercial vehicles usually includes multiple electrical devices such as parking air conditioners, entertainment systems, and professional work electrical appliances. These devices need to continue to work after the vehicle is turned off, which places high demands on the battery's range.

[0003] However, the existing low-voltage battery management methods for commercial vehicles are relatively crude and lack an effective charging and discharging monitoring mechanism, which leads to frequent problems of over-discharging of batteries. At the same time, the characteristics of lead-acid batteries determine that after repeated over-discharging, the battery capacity will be greatly reduced, the lifespan will be significantly shortened, or even directly damaged.

[0004] However, the relevant technologies have at least one of the following problems: existing technologies usually install lead-acid battery managers, but their cost is still high, the current industry installation rate is extremely low, and they can only realize voltage and power detection functions, but cannot directly control the load switch, and cannot fundamentally solve the problem of over-discharge. Summary of the Invention

[0005] This invention addresses the technical problem that lead-acid battery managers can only detect voltage and charge, but cannot directly control load switches, thus failing to fundamentally solve the problem of over-discharge.

[0006] To address the aforementioned problems, this invention provides a negative electrode control circuit for a commercial vehicle mounting system. The negative electrode control circuit includes a battery positive electrode interface, a battery negative electrode interface, and an output interface. The battery positive electrode interface is connected to the positive terminal of the battery, the battery negative electrode interface is connected to the negative terminal of the battery, and the output interface is connected to the negative terminal of the electrical device. The negative electrode control circuit includes: a field-effect transistor (FET), which has a gate, a drain, and a source; the gate is connected to the battery positive electrode interface, the drain is connected to the output interface, and the source is connected to the battery negative electrode interface; and a controller, which monitors the battery voltage in real time and controls the conduction and cutoff of the FET based on the battery voltage, thereby controlling the connection state of the output interface and the battery negative electrode interface.

[0007] Compared with existing technologies, the technical effects achieved by this solution are as follows: The negative control circuit has only three external interfaces, employing a core combination of field-effect transistors (FETs) and a controller, resulting in a minimalist structure and significantly reduced manufacturing costs. The three-interface design facilitates installation of the negative control circuit, allowing direct connection to the battery and upper-mount electrical equipment, making it compatible with all 24V lead-acid battery commercial vehicles and offering strong compatibility. The conduction and cutoff of the FETs directly determine the connection status between the output interface and the battery negative interface, thereby controlling the power supply to the upper-mount system's electrical equipment. Compared to traditional mechanical switches, FETs offer advantages such as fast response speed, no contact wear, and low power consumption, meeting the frequent on / off requirements of commercial vehicle upper-mount systems. The controller enables real-time voltage detection and FET switching control to be linked, forming a closed-loop "detection-judgment-control" mechanism. Compared to traditional solutions that only detect voltage, this approach cuts off the over-discharge path at the source, providing more direct and efficient protection, effectively preventing vehicle starting failures and shortened battery life due to battery depletion.

[0008] In one embodiment of the present invention, the negative electrode control circuit further includes: a first transistor, which has a first base, a first collector, and a first emitter, the first base being connected to the controller through a first resistor, and the first emitter being grounded; a second transistor, which has a second base, a second collector, and a second emitter, the second base being connected to the first collector through a third resistor, the second emitter being connected to the positive terminal interface of the battery, and the second collector being connected to the gate through a seventh resistor; wherein the second base is also connected to the drain through an eleventh resistor and a first diode, the anode of the first diode being connected to the second base through the eleventh resistor, and the cathode of the first diode being connected to the drain.

[0009] Compared with existing technologies, the technical effects achieved by this solution are as follows: A two-stage driving circuit is constructed using a first transistor and a second transistor. The first and second transistors work together to control the conduction and turn-off of the field-effect transistor (FET), ensuring stable and rapid conduction of the FET and improving switching response speed. Simultaneously, the coordinated design of the first diode and the second transistor provides hardware-level protection against output short circuits. When an output short circuit occurs, the conduction loop is automatically cut off, avoiding the risk of device damage and improving circuit reliability. A self-locking loop is constructed using the eleventh resistor and the first diode. The controller only needs to output a momentary pulse to complete the FET conduction control, eliminating the need for continuous signal output, reducing controller power consumption. Even if the controller fails, the negative control circuit can still maintain its conduction state, ensuring continuous operation of the upper-mounted equipment. The third resistor is a pull-down resistor for the base of the second transistor, working with the first transistor to control the base voltage of the second transistor, ensuring that the second transistor accurately responds to the conduction state of the first transistor and preventing FET mis-conduction.

[0010] In one embodiment of the present invention, the negative electrode control circuit further includes: a fourth transistor, the fourth transistor having a fourth base, a fourth collector and a fourth emitter, the fourth base being connected to the controller through a fifth resistor, the fourth collector being connected to the gate, and the fourth emitter being grounded.

[0011] Compared with existing technologies, the technical advantages of this solution are as follows: A separate fourth transistor is used as the turn-off driver, connected independently to the controller via a fifth resistor, forming an independent turn-off control link. This avoids conflicts with the turn-on control signal, ensuring precise and thorough turn-off of the MOSFET without leakage risk. Once the fourth transistor is turned on, it can directly pull down the MOSFET gate voltage, achieving millisecond-level turn-off response. In emergency scenarios such as battery undervoltage, it can quickly cut off power supply, effectively protecting the battery. Furthermore, the independent turn-off link design makes the circuit control logic clearer, facilitating debugging and maintenance, and reducing the failure rate.

[0012] In one embodiment of the present invention, the negative control circuit further includes an NTC resistor, one end of which is connected to the gate and the other end of which is grounded; wherein the NTC resistor and the field-effect transistor are arranged adjacent to each other.

[0013] Compared with existing technologies, the technical effects achieved by this solution are as follows: The NTC resistor is placed adjacent to the field-effect transistor, which can detect the device temperature in real time. Utilizing its negative temperature coefficient characteristic, the resistance automatically decreases when the field-effect transistor temperature rises due to overcurrent or high temperature, thereby reducing the gate drive voltage. When the temperature reaches a set threshold, the gate voltage drops to the turn-off threshold, and the field-effect transistor automatically turns off, achieving dual protection against overcurrent and overheating. This prevents the device from being damaged due to overload or high temperature. The overcurrent protection and overtemperature protection mechanisms are implemented purely in hardware, with a short response time. Compared with software protection, it is faster and more reliable, and adaptable to the complex load and environmental conditions of commercial vehicles.

[0014] In one embodiment of the present invention, the negative electrode control circuit further includes: a voltage divider circuit, which is connected in series between the battery positive terminal interface and ground, and the voltage divider circuit includes a ninth resistor and a tenth resistor. The first end of the ninth resistor is connected to the battery positive terminal interface, the second end of the ninth resistor is connected to one end of the tenth resistor, and the other end of the tenth resistor is grounded; wherein, a voltage divider node is provided between the ninth resistor and the tenth resistor, and the voltage divider node is connected to the controller through an eighth resistor.

[0015] Compared with the prior art, the technical effects achieved by adopting this technical solution are as follows: by reasonably selecting the resistance ratio of the ninth and tenth resistors, the voltage signal of the voltage divider node can accurately reflect the battery voltage (referring to the actual voltage of the battery in this application), providing an accurate basis for the controller's voltage judgment. The resistance ratio directly determines the voltage detection accuracy. The current limiting function of the eighth resistor can prevent excessive current from flowing into the controller port due to voltage fluctuations or circuit faults, further improving the stability and safety of the voltage detection module.

[0016] In one embodiment of the present invention, the negative electrode control circuit further includes a second diode, the cathode of which is connected to the gate and the anode of which is grounded.

[0017] Compared with existing technologies, the technical effects achieved by this solution are as follows: the second diode is connected in reverse parallel between the gate and ground, and operates in reverse breakdown mode, which can clamp the gate voltage of the field-effect transistor within a safe range; when the drive voltage fluctuates or a surge voltage occurs, the second diode automatically breaks down and conducts, clamping the gate voltage of the field-effect transistor within a safe range, effectively protecting the field-effect transistor from overvoltage damage; this design has a simple structure and extremely low cost, which can significantly reduce circuit failures caused by gate damage and improve the overall stability and service life of the circuit.

[0018] In one embodiment of the present invention, the negative electrode control circuit further includes a fourth resistor, one end of which is connected to the positive electrode interface of the battery, and the other end of which is connected to the second base.

[0019] Compared with existing technologies, the technical effects achieved by this technical solution are as follows: The fourth resistor is a pull-up resistor for the base of the second transistor. When there is no turn-on control signal, it pulls the base voltage of the second transistor to the power supply voltage, ensuring that the second transistor is reliably turned off and avoiding the field-effect transistor from being mis-turned on.

[0020] On the other hand, embodiments of the present invention also provide a negative electrode control method for a commercial vehicle superstructure system. This negative electrode control method is applied to the negative electrode control circuit of the commercial vehicle superstructure system as described in the first embodiment. The negative electrode control method includes: after the superstructure system is powered on, real-time detection of the battery voltage to determine whether the battery voltage is within the normal range; when the battery voltage is within the normal range, the controller controls the field-effect transistor to conduct, connecting the control output interface to the battery negative electrode interface; controlling the on / off state of the field-effect transistor according to the relationship between the battery voltage and a first voltage threshold; when the battery voltage is greater than or equal to the first voltage threshold, the field-effect transistor remains on; and / or when the battery voltage is less than the first voltage threshold, the controller controls the field-effect transistor to turn off, and the superstructure system enters a warning stage; after the warning stage ends, the controller controls the field-effect transistor to conduct again, controlling the on / off state of the field-effect transistor according to the relationship between the battery voltage and the first voltage threshold.

[0021] Compared with existing technologies, the technical effects achieved by this solution are as follows: The negative control circuit will monitor the battery voltage in real time. When the vehicle is powered by the battery after it is turned off, if the battery voltage reaches the undervoltage threshold, the negative control circuit will automatically shut off the negative output until the battery voltage returns to normal. This completely eliminates the problem of lead-acid battery depletion caused by the continuous power consumption of the superstructure system after the vehicle is turned off, significantly improves the stability and durability of lead-acid batteries in complex environments, reduces after-sales replacement and maintenance costs, and reduces business risks such as customer claims due to vehicle operation interruption. This application accurately controls the battery discharge state through two-stage undervoltage control and real-time voltage monitoring, preventing excessive discharge caused by continuous power consumption of the superstructure system, avoiding vehicle starting failure, and extending battery life.

[0022] In one embodiment of the present invention, the negative electrode control method further includes: acquiring the real-time temperature of the field-effect transistor; controlling the on / off state of the field-effect transistor according to the relationship between the real-time temperature and a temperature threshold; when the real-time temperature is greater than the temperature threshold, the gate voltage of the field-effect transistor drops to the turn-off voltage threshold, and the field-effect transistor is automatically turned off.

[0023] Compared with existing technologies, the technical effects achieved by this solution are as follows: the on / off state of the field-effect transistor is controlled according to its real-time temperature. When the temperature of the field-effect transistor reaches the set first temperature threshold, the gate voltage of the field-effect transistor will be reduced to the turn-off voltage threshold, and the field-effect transistor will be automatically turned off. Only when the real-time temperature drops to a certain level can the field-effect transistor be turned on normally, thus achieving over-temperature protection.

[0024] By adopting the technical solution of the present invention, the following technical effects can be achieved: (1) The negative control circuit has only three external interfaces. It adopts a core combination of field-effect transistors and controllers, which is extremely simple in structure and greatly reduces manufacturing costs. The three-interface design makes the negative control circuit easy to install and can be directly connected to the battery and the upper-mounted electrical equipment. It is compatible with all 24V lead-acid battery commercial vehicles and has strong compatibility. (2) By using the controller to realize the linkage between real-time voltage detection and field-effect transistor switch control, a closed-loop mechanism of "detection-judgment-control" is formed. Compared with the traditional solution that can only detect, it can cut off the over-discharge path from the source, providing more direct and efficient protection, and effectively avoiding the problem of vehicle failure to start and shortened battery life caused by battery depletion. (3) The NTC resistor in this application provides overcurrent and overheat protection, the first diode and the second transistor provide short circuit protection, and the second diode provides gate voltage regulation protection, thus avoiding the risk of circuit failure in all aspects. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 This is a circuit diagram of a negative control circuit for a commercial vehicle mounting system provided in Embodiment 1 of the present invention; Figure 2 For use Figure 1 System schematic diagram of the negative electrode controller in the intermediate negative electrode control circuit; Figure 3 This is a flowchart of a negative electrode control method for a commercial vehicle superstructure system provided in Embodiment 2 of the present invention; Figure 4 for Figure 3 Pulse diagram of the negative electrode control method.

[0026] Explanation of reference numerals in the attached figures: 1. Negative terminal controller; 2. Distribution box; 3. Battery; 31. Battery positive terminal; 32. Battery negative terminal; 10. Negative terminal control circuit; 11. Battery positive terminal interface; 12. Battery negative terminal interface; 13. Output interface; 131. Air conditioning system; 132. Upper structure system; 110. Controller; 111. Open port; 112. Close port; 113. Voltage detection port. Detailed Implementation

[0027] To make the above-mentioned objectives, features, and advantages of the present invention more apparent and understandable, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1 See Figure 1 This invention provides a negative control circuit for a commercial vehicle mounting system, as shown in the first embodiment. The negative control circuit 10 includes a battery positive interface 11, a battery negative interface 12, and an output interface 13. The battery positive interface 11 is connected to the positive terminal 31 of the battery, the battery negative interface 12 is connected to the negative terminal 32 of the battery, and the output interface 13 is connected to the negative terminal of the electrical equipment. The negative control circuit 10 includes a field-effect transistor (FET) and a controller 110. The FET has a gate, a drain, and a source. The gate is connected to the battery positive interface 11, the drain is connected to the output interface 13, and the source is connected to the battery negative interface 12. The controller 110 detects the battery voltage in real time and controls the conduction and cutoff of the FET according to the battery voltage, thereby controlling the connection state of the output interface 13 and the battery negative interface 12.

[0029] In one specific embodiment, the negative control circuit 10 of this application has only three external interfaces: a battery positive interface 11, an output interface 13, and a battery negative interface 12. The structure is extremely simple and easy to install and integrate: the battery positive interface 11 is connected to the positive terminal 31 of the battery to supply power to the entire negative control circuit 10; the battery negative interface 12 is connected to the negative terminal 32 of the battery; the output interface 13 is directly connected to the negative terminal of the electrical equipment that needs to be controlled, which is the ground of the electrical equipment; Q3 is a field-effect transistor, and Q3 acts as a low-side MOSFET switch. The negative control circuit 10 controls whether the output interface 13 is connected to the negative terminal 32 of the battery by controlling the conduction and shutdown of the field-effect transistor.

[0030] In this application, the on / off state of the field-effect transistor directly determines the connection state between the output interface 13 and the battery negative terminal interface 12, thereby controlling the power supply on / off of the equipment in the superstructure system. Compared with traditional mechanical switches, the field-effect transistor has the advantages of fast response speed, no contact wear, and low power consumption, and can adapt to the frequent on / off requirements of the superstructure system of commercial vehicles. The negative terminal controller 1 has a negative terminal control circuit 10, and the negative terminal controller 1 is directly installed on the negative terminal 32 of the battery. It is easy to install and use, low cost, and does not require modification of the original vehicle electrical system. It supports OEM production and aftermarket modification. A single negative terminal controller 1 can control multiple superstructure equipment in a unified manner and is compatible with all 24V lead-acid battery commercial vehicles.

[0031] Furthermore, the negative electrode control circuit 10 also includes: a first transistor and a second transistor. The first transistor has a first base, a first collector, and a first emitter. The first base is connected to the controller 110 through a first resistor, and the first emitter is grounded. The second transistor has a second base, a second collector, and a second emitter. The second base is connected to the first collector through a third resistor, and the second emitter is connected to the battery positive terminal interface 11. The second collector is connected to the gate through a seventh resistor. The second base is also connected to the drain through an eleventh resistor and a first diode. The anode of the first diode is connected to the second base through the eleventh resistor, and the cathode of the first diode is connected to the drain.

[0032] Specifically, Q1 is the first transistor, which is an NPN transistor; Q2 is the second transistor, which is a PNP transistor; R1 is the first resistor, R3 is the third resistor, R7 is the seventh resistor, R11 is the eleventh resistor, and D1 is the first diode. The first and second transistors work together to control the on and off states of the field-effect transistor, ensuring stable and fast on-state conduction of the field-effect transistor, improving the switching response speed, and simultaneously achieving a latching function in conjunction with subsequent circuitry.

[0033] The principle of controller 110 controlling the opening of the field-effect transistor and maintaining circuit self-locking is as follows: After controller 110 outputs a high-level pulse through the opening port 111, the first transistor will turn on. After the first transistor is turned on, the second base of the second transistor is pulled low through the third resistor, and the second transistor is turned on. The battery voltage is divided and drives the field-effect transistor to turn on and conduct. After the field-effect transistor is turned on, the output interface 13 is connected to the negative terminal 32 of the battery, that is, the output becomes low (output interface 13 becomes low level). After the output is low, the second base will be grounded through the eleventh resistor and the first diode, forming a self-locking circuit. At this time, even if controller 110 turns off the first transistor or stops outputting control signals, the second transistor will continue to conduct, improving circuit reliability. In other words, the output of the field-effect transistor achieves self-locking.

[0034] Meanwhile, the negative control circuit 10, using pulse switching for control and self-locking for output retention, can achieve automatic hardware protection against power supply short circuits. The short-circuit protection principle of the field-effect transistor (FET) is as follows: when the FET output is normal, the FET is turned on, and the output is low. The second base of the second transistor is pulled low through the first diode, and the conduction of the second transistor is maintained. If the FET output is short-circuited to the power supply, the cathode of the first diode will change from low to high, the first diode will no longer conduct, the second transistor will automatically turn off, and then the FET will also turn off. Simultaneously, the self-locking of the negative control circuit 10 will automatically fail.

[0035] Furthermore, the negative control circuit 10 also includes a fourth transistor, which has a fourth base, a fourth collector and a fourth emitter. The fourth base is connected to the controller 110 through a fifth resistor, the fourth collector is connected to the gate and the fourth emitter is grounded.

[0036] Specifically, Q4 is the fourth transistor, which is an NPN transistor, and R5 is the fifth resistor. The controller 110 also has a shutdown port 112, which is connected to the fourth base of the fourth transistor via the fifth resistor. The fourth emitter is grounded, and the fourth collector is connected to the gate of the field-effect transistor, thus controlling the shutdown of the field-effect transistor.

[0037] The principle of controller 110 controlling the shutdown of the field-effect transistor and the failure of the circuit self-locking maintenance is as follows: controller 110 outputs a high-level pulse to drive the first and second transistors to conduct through the open port 111, thereby controlling the field-effect transistor to turn on. When controller 110 outputs a high-level pulse to turn off through the close port 112, the fourth transistor will turn on and conduct. After the fourth transistor is turned on, it directly pulls the gate of the field-effect transistor low, and the field-effect transistor is turned off. Since the first transistor is also in the off state, the second base of the second transistor will change from low to high, and the second transistor will also turn off. At this time, the self-locking maintenance of the negative control circuit 10 is interrupted, and the field-effect transistor will remain in the off state.

[0038] Preferably, the negative control circuit 10 further includes a sixth resistor R6. The shut-off port 112 is connected to one end of the sixth resistor, and the other end of the sixth resistor is grounded. The sixth resistor is a pull-down resistor. When there is no control signal, the sixth resistor pulls the base voltage of the fourth transistor to ground potential, ensuring that the fourth transistor is reliably cut off and avoiding false triggering due to the base being floating.

[0039] Furthermore, the negative control circuit 10 also includes an NTC resistor, one end of which is connected to the gate and the other end of which is grounded; wherein the NTC resistor and the field-effect transistor are arranged adjacent to each other.

[0040] Specifically, This is an NTC resistor, or negative temperature coefficient resistor. One end of the NTC resistor is connected to the gate, and the other end is grounded. The NTC resistor is used to monitor the temperature of the field-effect transistor in real time. Because the seventh resistor forms a voltage divider with the NTC resistor, the NTC resistor can be used for over-temperature control of the field-effect transistor gate drive. Over-temperature of the field-effect transistor is usually caused by overcurrent heating, or it may be caused by excessively high ambient temperature. Overcurrent protection means that when the load current exceeds the rated value, the temperature of the field-effect transistor will exceed the rated temperature. The NTC resistor will turn off the field-effect transistor to prevent it from being damaged by overload.

[0041] The gate drive voltage of the field-effect transistor is: , This is the gate drive voltage of the field-effect transistor. The battery voltage; the over-temperature protection principle of the field-effect transistor is: because Located near Q3, as the temperature of Q3 gradually increases, The resistance will continue to decrease. It will also decrease; when the temperature of Q3 reaches the set over-temperature threshold, The temperature will drop to the shutdown threshold of Q3, and Q3 will automatically shut down; only when the temperature of Q3 drops to a certain level will it shut down. After the resistance rises to a certain value, Only when the current rises to its conduction threshold can Q3 be turned on normally.

[0042] The resistance of the NTC resistor decreases as the temperature rises. It is connected in series in the gate drive link of the field-effect transistor (FET) to achieve dual protection against overcurrent and overheating: when the FET is overloaded and the current is too high or the ambient temperature is too high, the temperature of the FET rises and the resistance of the NTC resistor decreases accordingly, causing the gate drive voltage to drop; when the temperature reaches the set threshold, the gate voltage drops to the turn-off threshold of the FET, and the FET automatically turns off and stops supplying power, preventing the FET from being damaged by overcurrent or overheating.

[0043] Furthermore, the negative control circuit 10 also includes a voltage divider circuit, which is connected in series between the battery positive terminal interface 11 and ground. The voltage divider circuit includes a ninth resistor and a tenth resistor. The first end of the ninth resistor is connected to the battery positive terminal interface 11, the second end of the ninth resistor is connected to one end of the tenth resistor, and the other end of the tenth resistor is grounded. A voltage divider node is provided between the ninth resistor and the tenth resistor, and the voltage divider node is connected to the controller 110 through an eighth resistor.

[0044] Specifically, R8 is the eighth resistor, R9 is the ninth resistor, and R10 is the tenth resistor. The ninth and tenth resistors form a voltage divider circuit connected in series between the battery positive terminal 11 and the ground terminal. The voltage divider node is connected to the voltage detection port 113 of the controller 110 through the eighth resistor. The controller 110 collects the voltage divider signal and calculates the battery voltage in real time. , The controller detects the voltage signal (i.e., the voltage divider signal), and the controller then... , and The value was converted to obtain The controller 110 detects the battery voltage through a voltage divider circuit composed of the ninth and tenth resistors, and collects and calculates the battery voltage in real time. The eighth resistor is connected in series between the voltage divider node and the voltage detection port 113, which serves to limit current and protect the port. This enables real-time acquisition and accurate detection of the battery voltage, preventing excessive current from flowing into the controller 110 due to battery voltage fluctuations or voltage divider circuit failures, thus avoiding damage to the controller 110 port and improving the stability and safety of voltage detection.

[0045] Furthermore, the negative control circuit 10 also includes a second diode, the cathode of which is connected to the gate, and the anode of which is grounded.

[0046] Specifically, D2 is the second diode, which is a Zener diode. The cathode of the second diode is connected to the gate of the field-effect transistor, and the anode of the second diode is grounded. The second diode can clamp the gate voltage of the field-effect transistor within a safe range, realize gate voltage regulation protection, avoid gate breakdown damage caused by excessive drive voltage or surge voltage in the circuit, comprehensively avoid circuit failure risks, and protect the core switching device.

[0047] Furthermore, the negative electrode control circuit 10 also includes a fourth resistor, one end of which is connected to the positive electrode interface 11 of the battery, and the other end of which is connected to the second base.

[0048] Specifically, R4 is the fourth resistor, which is the pull-up resistor for the base of the second transistor. When there is no turn-on control signal, it pulls the base voltage of the field-effect transistor to the power supply voltage, ensuring that the second transistor is reliably turned off and preventing the field-effect transistor from being mistakenly turned on.

[0049] Figure 2 This is a system diagram of the negative controller 1 using the negative control circuit 10 of this application. The negative controller 1 using the negative control circuit 10 can be directly installed near the negative terminal 32 of the vehicle battery. The negative controller 1 has three interfaces (which can be the same as the negative control circuit 10): output interface 13, battery positive terminal interface 11, and battery negative terminal interface 12. The output interface 13 can be directly connected to the negative terminal of all electrical devices that need to be controlled by the negative terminal, such as the air conditioning system 131, the superstructure system 132, etc. The negative terminals of these electrical devices can be controlled by the negative controller 1. The positive terminal of the electrical device, i.e., the power supply, still goes through the vehicle's power distribution box 2.

[0050] For the original vehicle system, any electrical device that requires negative control draws power from the original vehicle power distribution box 2. The power distribution box 2 can also protect the electrical device while distributing the power.

[0051]

Example 2

[0052] In one specific embodiment, the negative electrode control method is based on the voltage detection result of the controller and adopts a two-stage undervoltage control strategy, combined with pulse control and a self-locking mechanism. The specific steps are as follows: ①. After the upper-mount system is powered on and initialized, the controller immediately detects the battery voltage through a voltage divider circuit to determine whether the battery voltage is within the normal range (the normal range can be configured according to the actual application, for example, the normal range is 24V±0.5V); ②. If the battery voltage is normal, the controller outputs a millisecond-level high-level pulse to start the negative electrode control circuit, turn on the field-effect transistor, and connect the output interface to the battery negative electrode interface to provide negative electrode power supply to the upper-mount system and other electrical equipment that require negative electrode control; if the battery voltage is abnormal, the field-effect transistor is not turned on, and the controller continues to detect the voltage. ③. During the power supply process, the controller will continue to monitor the battery voltage in real time. When the battery voltage drops to the undervoltage threshold (in this application, the undervoltage threshold is represented by the first voltage threshold), the controller outputs a high-level pulse to turn off, and the field-effect transistor turns off for a first duration (the first duration can be configured according to the actual application). At this time, the negative control circuit automatically turns off the negative output and enters the warning stage to remind the user to handle it in time. ④. After the warning ends, the controller outputs a high-level pulse to turn on again to try to turn on the field-effect transistor: if the battery voltage returns to normal, the power supply state is maintained; if the battery voltage is still in the undervoltage state, the field-effect transistor is completely turned off until the battery voltage returns to normal before the power supply process can be restarted and the field-effect transistor can be turned on again.

[0053] This application combines an early warning mechanism with a complete shutdown strategy, which not only avoids frequent shutdowns affecting use, but also effectively protects the battery and improves the user experience. Preferably, the undervoltage threshold is set according to the requirements of the vehicle manufacturer, and the preferred value for the first duration is 1 minute.

[0054] Preferred, see Figure 4 The controller controls the negative control circuit via pulse signals. That is, when the negative control circuit is in the off state, if it needs to be turned on, the controller outputs a high-level pulse. The pulse width depends on the characteristics of the circuit and is usually in the millisecond range. For example, the field-effect transistor can be turned on after the controller outputs the turn-on pulse for 0.1 milliseconds. At this time, the negative control circuit can enter the self-locking maintenance state, and the output can continue to maintain the open state. Therefore, setting the turn-on pulse to 5 milliseconds can fully meet the control requirements.

[0055] When the controller needs to turn off the field-effect transistor, only one high-level turn-off pulse needs to be output. The pulse width depends on the characteristics of the circuit and is usually in the millisecond range. For example, the field-effect transistor can be turned off after the controller outputs a turn-off pulse of 0.1 milliseconds. At this time, the negative control circuit can enter the turn-off state, and the output can continue to maintain the turn-off state. Therefore, setting the turn-off pulse to 5 milliseconds can fully meet the control requirements.

[0056] Furthermore, negative electrode control methods also include: Obtain the real-time temperature of the field-effect transistor; The on / off state of the field-effect transistor is controlled based on the relationship between the real-time temperature and the first temperature threshold. When the real-time temperature exceeds the first temperature threshold, the gate voltage of the field-effect transistor drops to the turn-off voltage threshold, and the field-effect transistor automatically turns off.

[0057] Specifically, the over-temperature protection principle is as follows: based on the real-time temperature of the field-effect transistor (FET), the switching on and off of the FET is controlled. When the temperature of the FET reaches the set first temperature threshold, the gate voltage of the FET will drop to the turn-off threshold (i.e., the turn-off voltage threshold), and the FET will automatically turn off. Only when the real-time temperature drops to a certain level (for example, when the real-time temperature drops to the second temperature threshold), and the resistance of the NTC resistor rises to a certain value, will the gate voltage of the FET rise to its turn-on threshold, and the FET can be turned on normally.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A negative control circuit for a commercial vehicle superstructure system, characterized in that, The negative electrode control circuit (10) is provided with a battery positive electrode interface (11), a battery negative electrode interface (12), and an output interface (13). The battery positive electrode interface (11) is connected to the positive electrode (31) of the storage battery, the battery negative electrode interface (12) is connected to the negative electrode (32) of the storage battery, and the output interface (13) is connected to the negative electrode of the electrical equipment. The negative electrode control circuit (10) includes: A field-effect transistor, wherein the field-effect transistor has a gate, a drain and a source, the gate is connected to the positive terminal interface (11) of the battery, the drain is connected to the output interface (13) and the source is connected to the negative terminal interface (12) of the battery; The controller (110) detects the battery voltage in real time and controls the conduction and cutoff of the field-effect transistor according to the battery voltage, thereby controlling the connection state of the output interface (13) and the battery negative terminal interface (12).

2. The negative electrode control circuit according to claim 1, characterized in that, The negative control circuit (10) further includes: The first transistor has a first base, a first collector and a first emitter. The first base is connected to the controller (110) through a first resistor, and the first emitter is grounded. The second transistor has a second base, a second collector, and a second emitter. The second base is connected to the first collector through a third resistor, the second emitter is connected to the positive terminal interface (11) of the battery, and the second collector is connected to the gate through a seventh resistor. The second base is connected to the drain via an eleventh resistor and a first diode. The anode of the first diode is connected to the second base via the eleventh resistor, and the cathode of the first diode is connected to the drain.

3. The negative electrode control circuit according to claim 2, characterized in that, The negative control circuit (10) further includes: The fourth transistor has a fourth base, a fourth collector and a fourth emitter. The fourth base is connected to the controller (110) through a fifth resistor. The fourth collector is connected to the gate and the fourth emitter is grounded.

4. The negative electrode control circuit according to any one of claims 1-3, characterized in that, The negative control circuit (10) further includes: An NTC resistor, one end of which is connected to the gate, and the other end of which is grounded; The NTC resistor and the field-effect transistor are arranged adjacent to each other.

5. The negative electrode control circuit according to any one of claims 1-3, characterized in that, The negative control circuit (10) further includes: A voltage divider circuit is connected in series between the battery positive terminal interface (11) and ground. The voltage divider circuit includes a ninth resistor and a tenth resistor. The first end of the ninth resistor is connected to the battery positive terminal interface (11), the second end of the ninth resistor is connected to one end of the tenth resistor, and the other end of the tenth resistor is grounded. A voltage divider node is provided between the ninth resistor and the tenth resistor, and the voltage divider node is connected to the controller (110) through the eighth resistor.

6. The negative electrode control circuit according to claim 1, characterized in that, The negative control circuit (10) further includes: A second diode, the cathode of which is connected to the gate, and the anode of which is grounded.

7. The negative electrode control circuit according to claim 2, characterized in that, The negative control circuit (10) further includes: A fourth resistor, one end of which is connected to the positive terminal interface (11) of the battery, and the other end of which is connected to the second base.

8. A negative electrode control method for a commercial vehicle superstructure system, characterized in that, The negative electrode control method is applied to the negative electrode control circuit for a commercial vehicle superstructure system as described in any one of claims 1-7, and the negative electrode control method includes: After the superstructure system is powered on, the battery voltage is monitored in real time to determine whether the battery voltage is within the normal range. When the battery voltage is within the normal range, the controller controls the field-effect transistor to turn on and controls the output interface to connect with the battery negative terminal interface (12); The on / off state of the field-effect transistor is controlled according to the relationship between the battery voltage and the first voltage threshold. When the battery voltage is greater than or equal to the first voltage threshold, the field-effect transistor remains on; and / or When the battery voltage is less than the first voltage threshold, the controller controls the field-effect transistor to turn off, and the superstructure system enters the early warning stage; After the warning phase ends, the controller turns the field-effect transistor on again and controls the on / off state of the field-effect transistor according to the relationship between the battery voltage and the first voltage threshold.

9. The negative electrode control method according to claim 8, characterized in that, The negative electrode control method further includes: Obtain the real-time temperature of the field-effect transistor; The on / off state of the field-effect transistor is controlled according to the relationship between the real-time temperature and the first temperature threshold. When the real-time temperature is greater than the first temperature threshold, the gate voltage of the field-effect transistor drops to the turn-off voltage threshold, and the field-effect transistor is automatically turned off.

Images