Double under-voltage protection circuit and vehicle power line

Abstract

The utility model discloses a double under-voltage protection circuit and a vehicle power line, relates to the technical field of power supply protection, and solves the technical problem that the existing vehicle power line with under-voltage protection can only be applied to an automobile with the same voltage system and is poor in flexibility. The circuit comprises a switching power supply unit and an under-voltage regulation unit, the input end of the switching power supply unit is connected with a power supply and the output end is connected with a load; the switching power supply unit is used for charging the load; the under-voltage adjusting unit is connected with an enabling interface of the switching power supply unit; the under-voltage adjusting unit is used for adjusting an under-voltage protection point of the switching power supply unit. The circuit provided by the utility model is high in universality and low in cost.

Description

Technical Field

[0001] This utility model relates to the field of power protection technology, and in particular to a dual undervoltage protection circuit and a vehicle power cord. Background Technology

[0002] With the increasing popularity of electric and hybrid vehicles, automotive power cables, as crucial components connecting the power source to the car battery, have received widespread attention regarding their performance and safety. Currently, most commercially available automotive power cables are equipped with undervoltage protection to prevent the battery from continuing to discharge when the voltage is too low, thus protecting it from damage. However, existing automotive power cables with undervoltage protection have certain limitations.

[0003] In 12V vehicles, when the battery is in an undervoltage state (i.e., the battery voltage is below 12V), the undervoltage protection function of the vehicle charging cable can activate in time, stopping power output and preventing further battery discharge. This protection mechanism performs well in 12V vehicle systems, effectively preventing battery damage due to over-discharge. However, problems arise when the same vehicle charging cable is used in 24V vehicles. In a 24V system, a battery undervoltage state typically refers to a voltage below 24V. However, because the existing undervoltage protection point is designed for 12V, the vehicle charging cable may not be able to recognize and stop working in time when a 24V battery is in a low-voltage state. This allows the battery to continue discharging, leading to over-discharge, which not only accelerates battery degradation but may also cause irreversible damage. Therefore, this method can only be used in vehicles with the same voltage system.

[0004] In the process of developing this utility model, the applicant discovered at least the following problems in the prior art:

[0005] Existing automotive power cables with undervoltage protection can only be used in cars with the same voltage system, which is not very flexible. Utility Model Content

[0006] The purpose of this invention is to provide a dual undervoltage protection circuit and an automotive power cord, to solve the technical problem that existing automotive power cords with undervoltage protection can only be used in vehicles with the same voltage system, resulting in poor flexibility. The various technical effects of the preferred solutions among the many technical solutions provided by this invention are detailed below.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] This utility model provides a dual undervoltage protection circuit, including a switching power supply unit and an undervoltage adjustment unit; the input terminal of the switching power supply unit is connected to a power source, and the output terminal is connected to a load; the switching power supply unit is used to charge the load; the undervoltage adjustment unit is connected to the enable interface of the switching power supply unit; the undervoltage adjustment unit is used to adjust the undervoltage protection point of the switching power supply unit.

[0009] The undervoltage regulation unit includes a power supply voltage detector U2, a MOSFET Q1, resistors R3, R4, and R6. The input terminal of the power supply voltage detector U2 is connected to a reference voltage, and the output terminal is connected to the gate of the MOSFET Q1. The drain of the MOSFET Q1 is connected to the first terminal of the resistor R6, and the source is grounded. The second terminal of the resistor R6 is connected to the switching power supply unit. The first terminal of the resistor R3 is connected to the reference voltage, and the second terminal is connected to the first terminal of the resistor R4 and the switching power supply unit. The first terminal of the resistor R4 is also connected to the switching power supply unit and the second terminal of the resistor R6, and the second terminal of the resistor R4 is grounded.

[0010] Optionally, the switching power supply unit includes a buck converter chip U1; the input pin of the buck converter chip U1 is connected to the power supply, the input pin is connected to the load, and the enable pin is connected to the second end of the resistor R3, the first end of the resistor R4, and the second end of the resistor R6.

[0011] Optionally, the buck converter chip U1 is model TLVM13620.

[0012] Optionally, the dual undervoltage protection circuit further includes a first filtering unit and a second filtering unit; the first filtering unit is disposed between the power supply and the switching power supply unit; the second filtering unit is disposed between the switching power supply and the load.

[0013] Optionally, the first filtering unit includes inductor B2, inductor B4, capacitor C6, capacitor C7, and capacitor C5; one end of inductor B2 is connected to the positive terminal of the power supply, and the other end is connected to the input pin of the step-down chip U1; one end of inductor B4 is connected to the negative terminal of the power supply, and the other end is connected to the input pin of the step-down chip U1; capacitors C6, C7, and C5 are all connected in parallel between inductor B2 and inductor B4.

[0014] Optionally, the first filtering unit further includes a diode D1; the diode D1 is a transient voltage suppression diode used to suppress instantaneous overvoltage of the power supply; the cathode of the diode D1 is connected to the positive terminal of the power supply, and the anode is connected to the negative terminal of the power supply.

[0015] Optionally, the second filtering unit includes inductor B1, inductor B3, capacitor C3, capacitor C2, and capacitor C4; one end of inductor B1 is connected to the power supply interface of the load, and the other end is connected to the output pin of the step-down chip U1; one end of inductor B3 is connected to the ground wire of the load, and the other end is connected to the output pin of the step-down chip U1; capacitors C3, C2, and C4 are all connected in parallel between inductor B1 and inductor B3.

[0016] Optionally, the power supply voltage detector U2 is model SSP61CC3002MR.

[0017] Optionally, the undervoltage regulation unit further includes resistors R8 and R9 for selecting one of the two undervoltage protection points; the first end of resistor R8 is connected to the reference voltage, and the second end is connected to the first end of resistor R9 and the input terminal of the power supply voltage detector U2; the first end of resistor R9 is also connected to the input terminal of the power supply voltage detector U2, and the second end is grounded.

[0018] A vehicle power cord, comprising any of the above-described dual undervoltage protection circuits.

[0019] Implementing one of the above-described technical solutions of this utility model has the following advantages or beneficial effects:

[0020] The dual undervoltage protection circuit provided by this utility model has two undervoltage protection points, and the undervoltage protection points of the switching power supply unit are adjusted by an undervoltage adjustment unit. This allows the automotive power cable using this circuit to be used in cars with two different voltage systems, improving the flexibility of the automotive power cable. In addition, the circuit has a simple structure, low production cost, and can improve energy efficiency. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0022] Figure 1 This is a circuit structure diagram of the dual undervoltage protection circuit of Embodiment 1 of this utility model;

[0023] In the diagram: 1. Switching power supply unit; 2. Undervoltage regulation unit; 3. First filter unit; 4. Second filter unit. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this utility model clearer, various exemplary embodiments described below will be referenced to the accompanying drawings, which form part of the exemplary embodiments, illustrating various exemplary embodiments that may be adopted to implement this utility model. Unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. It should be understood that they are merely examples of processes, methods, and apparatuses consistent with some aspects of this utility model disclosed as detailed in the appended claims, and other embodiments may be used, or structural and functional modifications may be made to the embodiments listed herein without departing from the scope and spirit of this utility model.

[0025] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," etc., indicate the orientation or positional relationship based on the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the referred element must have a specific orientation, or be constructed and operated in a specific orientation. The terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. The term "multiple" means two or more. The terms "connected" and "linked" should be interpreted broadly, for example, they can be fixed connections, detachable connections, integral connections, mechanical connections, electrical connections, communication connections, direct connections, indirect connections through an intermediate medium, and can be the internal connection of two elements or the interaction relationship between two elements. The term "and / or" includes any and all combinations of one or more of the related listed items. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0026] To illustrate the technical solution described in this utility model, specific embodiments are described below, showing only the parts related to the embodiments of this utility model.

[0027] Example 1:

[0028] like Figure 1As shown, this utility model provides a dual undervoltage protection circuit, including a switching power supply unit 1 and an undervoltage adjustment unit 2. The input terminal of the switching power supply unit 1 is connected to a power source, and the output terminal is connected to a load. The switching power supply unit 1 is used to charge the load. The undervoltage adjustment unit 2 is connected to the enable interface of the switching power supply unit 1. The undervoltage adjustment unit 2 is used to adjust the undervoltage protection point of the switching power supply unit 1. The undervoltage adjustment unit 2 includes a power supply voltage detector U2, a MOSFET Q1, resistors R3, R4, and R6. The input terminal of the power supply voltage detector U2 is connected to a reference voltage, and the output terminal is connected to the gate of the MOSFET Q1. The drain of the MOSFET Q1 is connected to the first terminal of the resistor R6, and the source is grounded. The second terminal of the resistor R6 is connected to the switching power supply unit 1. The first terminal of the resistor R3 is connected to the reference voltage, and the second terminal is connected to the first terminal of the resistor R4 and the switching power supply unit 1. The first terminal of the resistor R4 is also connected to the switching power supply unit 1 and the second terminal of the resistor R6, and the second terminal of the resistor R4 is grounded.

[0029] The dual undervoltage protection circuit provided in this embodiment has two undervoltage protection points, and the undervoltage protection point of the switching power supply unit 1 is adjusted by the undervoltage adjustment unit 2, so that the automotive power cable using this circuit can be used in cars with two different voltage systems, improving the flexibility of the automotive power cable; moreover, the circuit has a simple structure, low production cost, and can improve energy efficiency.

[0030] As an optional implementation, the switching power supply unit 1 includes a buck converter chip U1. The input pin of the buck converter chip U1 is connected to the power supply, and the enable pin is connected to the second terminal of resistor R3, the first terminal of resistor R4, and the second terminal of resistor R6. The buck converter chip steps down the power supply voltage and then outputs a constant voltage to the load to ensure a stable output voltage for charging the load. The buck converter chip U1 is a TLVM13620. The TLVM13620 is a high-efficiency synchronous buck converter chip with an input voltage range of 4.5V to 36V, suitable for various applications. It also integrates high-side and low-side MOSFETs, enabling efficient synchronous rectification, improving efficiency while ensuring a stable output buck voltage. Furthermore, the chip uses a 3mm×3mm QFN package, occupying little space and simplifying circuit design.

[0031] As an alternative implementation, the power supply voltage detector U2 is model SSP61CC3002MR. The SSP61CC3002MR is a three-terminal low-power voltage detector implemented using CMOS technology. This voltage detector consists of a low-power standard voltage source, a comparator, a magnetic tape circuit, and an output driver. It features low power consumption and high accuracy, and can assist the undervoltage regulation unit 2 in detecting the input voltage so that the undervoltage regulation unit 2 can adjust the undervoltage protection point of the switching power supply unit 1.

[0032] The working principle of the dual undervoltage protection circuit provided in this embodiment will be explained in detail below, taking 12V series and 24V series automobiles as examples:

[0033] As an optional implementation, the undervoltage adjustment unit 2 further includes resistors R8 and R9 for selecting one of two undervoltage protection points; for example, when the circuit of this embodiment is used in a 12V series vehicle, the undervoltage protection point is selected as 12V; when the circuit of this embodiment is used in a 24V series vehicle, the undervoltage protection point is selected as 24V. The first end of resistor R8 is connected to the reference voltage, and the second end is connected to the first end of resistor R9 and the input terminal of the power supply voltage detector U2; the first end of resistor R9 is also connected to the input terminal of the power supply voltage detector U2, and the second end is grounded.

[0034] When the circuit of this embodiment is used in a 12V series vehicle, in the undervoltage regulation unit 2, the reference voltage VIN (reference voltage VIN is 12V) is input to the power supply voltage detector U2, causing the voltage detector U2 to output a low level, the MOSFET Q1 to be cut off, and the resistor R6 to be in an open circuit state. At this time, the voltage input from the undervoltage regulation unit 2 to the enable pin EN of the buck converter chip U1 is determined by the voltage division of the resistors R3 and R4, thereby making the undervoltage protection point of the buck converter chip U1 12V. When the load voltage is lower than 12V, the voltage at the enable pin EN of the buck converter chip U1 is lower than the enable voltage, the buck converter chip U1 shuts down the output, and the circuit stops working to prevent the power supply from continuing to discharge.

[0035] When the circuit of this embodiment is used in a 24V series vehicle, the reference voltage VIN (24V) is input to the power supply voltage detector U2, causing the voltage detector U2 to output a high level, turning on the MOSFET Q1, and grounding the first terminal of resistor R6. At this time, resistors R4 and R6 are connected in parallel, reducing the voltage divider resistance of the voltage input from the undervoltage regulation unit 2 to the enable pin EN of the buck converter chip U1, thereby making the undervoltage protection point of the buck converter chip U1 24V. When the load voltage is lower than 24V, the voltage at the enable pin EN of the buck converter chip U1 is lower than the enable voltage, the buck converter chip U1 shuts down its output, and the circuit stops working to prevent the power supply from continuing to discharge. Therefore, the circuit provided in this embodiment can be used in both 12V and 24V series vehicles without changing the circuit structure, increasing the versatility of the circuit.

[0036] As an alternative implementation, the dual undervoltage protection circuit further includes a first filter unit 3 and a second filter unit 4; the first filter unit 3 is disposed between the power supply and the switching power supply unit 1; the second filter unit 4 is disposed between the switching power supply and the load. Filter circuits are provided at both the input and output terminals of the switching power supply unit 1 to filter out high-frequency noise, stabilize the voltage, and provide clean power to the load.

[0037] As an alternative implementation, the first filter unit 3 includes inductors B2 and B4, and capacitors C6, C7, and C5. One end of inductor B2 is connected to the positive terminal of the power supply, and the other end is connected to the input pin of the step-down chip U1. One end of inductor B4 is connected to the negative terminal of the power supply, and the other end is connected to the input pin of the step-down chip U1. Capacitors C6, C7, and C5 are all connected in parallel between inductors B2 and B4. By using two inductors respectively at the positive and negative terminals of the power supply and connecting them in series with three resistors, noise can be effectively filtered and voltage stabilized.

[0038] As an optional implementation, the first filter unit 3 further includes a diode D1; diode D1 is a transient voltage suppression diode used to suppress instantaneous overvoltage of the power supply; the cathode of diode D1 is connected to the positive terminal of the power supply, and the anode is connected to the negative terminal of the power supply. Providing transient voltage suppression diodes at the positive and negative terminals of the power supply can protect the power supply and the circuit of this embodiment from the effects of power supply transients, thereby preventing damage to the power supply and the circuit of this embodiment.

[0039] As an alternative implementation, the second filter unit 4 includes inductors B1 and B3, and capacitors C3, C2, and C4. One end of inductor B1 is connected to the power supply interface of the load, and the other end is connected to the output pin of the buck converter chip U1. One end of inductor B3 is connected to the ground wire of the load, and the other end is connected to the output pin of the buck converter chip U1. Capacitors C3, C2, and C4 are all connected in parallel between inductors B1 and B3. Similarly, two inductors and three capacitors are also connected in parallel at the output of the buck converter chip U1 to effectively filter noise and stabilize the voltage.

[0040] The embodiment is merely a special case and does not indicate that this utility model is implemented in such a way.

[0041] Example 2:

[0042] The difference between this second embodiment and the first embodiment is that the second embodiment provides a vehicle power cord that includes a dual undervoltage protection circuit as described in any of the embodiments in the first embodiment. The vehicle power cord provided in this embodiment uses the dual undervoltage protection circuit described in the embodiments, enabling it to be used in vehicles with two different voltage systems, thus increasing the versatility of the power cord; moreover, the circuit structure is simple, greatly reducing the production cost of the power cord.

[0043] The above description is merely a preferred embodiment of the present utility model. Those skilled in the art will understand that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the present utility model. Furthermore, under the teachings of the present utility model, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the present utility model. Therefore, the present utility model is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present utility model.

Claims

1. A dual under-voltage protection circuit, characterized by, The double under-voltage protection circuit comprises a switching power supply unit and an under-voltage regulating unit; an input end of the switching power supply unit is connected with a power supply, and an output end thereof is connected with a load; the switching power supply unit is used for charging the load; the under-voltage regulating unit is connected with an enable interface of the switching power supply unit; and the under-voltage regulating unit is used for regulating an under-voltage protection point of the switching power supply unit. The under-voltage regulating unit comprises a power supply voltage detector U2, a MOS tube Q1, a resistor R3, a resistor R4 and a resistor R6; an input end of the power supply voltage detector U2 is connected with a reference voltage, and an output end thereof is connected with a gate of the MOS tube Q1; a drain of the MOS tube Q1 is connected with a first end of the resistor R6, and a source thereof is grounded; a second end of the resistor R6 is connected with the switching power supply unit; a first end of the resistor R3 is connected with the reference voltage, and a second end thereof is connected with a first end of the resistor R4 and the switching power supply unit; the first end of the resistor R4 is also connected with the switching power supply unit and the second end of the resistor R6, and a second end of the resistor R4 is grounded.

2. A dual under-voltage protection circuit according to claim 1, characterized in that The switching power supply unit comprises a step-down chip U1; an input pin of the step-down chip U1 is connected with the power supply, an input pin thereof is connected with the load, and an enable pin thereof is connected with the second end of the resistor R3, the first end of the resistor R4 and the second end of the resistor R6.

3. A dual under-voltage protection circuit according to claim 2, characterized in that The model of the step-down chip U1 is TLVM13620.

4. The dual under-voltage protection circuit of claim 2, wherein, The double under-voltage protection circuit further comprises a first filter unit and a second filter unit; the first filter unit is arranged between the power supply and the switching power supply unit; and the second filter unit is arranged between the switching power supply and the load.

5. A dual under-voltage protection circuit according to claim 4, characterized in that The first filter unit comprises an inductor B2, an inductor B4, a capacitor C6, a capacitor C7 and a capacitor C5; one end of the inductor B2 is connected with a positive pole of the power supply, and the other end thereof is connected with an input pin of the step-down chip U1; one end of the inductor B4 is connected with a negative pole of the power supply, and the other end thereof is connected with an input pin of the step-down chip U1; the capacitor C6, the capacitor C7 and the capacitor C5 are all connected in parallel between the inductor B2 and the inductor B4.

6. A dual under-voltage protection circuit according to claim 5, characterized in that The first filter unit further comprises a diode D1; the diode D1 is a transient voltage suppression diode, which is used for suppressing transient overvoltage of the power supply; a cathode of the diode D1 is connected with a positive pole of the power supply, and an anode thereof is connected with a negative pole of the power supply.

7. A dual under-voltage protection circuit according to claim 4, wherein The second filter unit comprises an inductor B1, an inductor B3, a capacitor C3, a capacitor C2 and a capacitor C4; one end of the inductor B1 is connected with a power supply interface of the load, and the other end thereof is connected with an output pin of the step-down chip U1; one end of the inductor B3 is connected with a ground wire of the load, and the other end thereof is connected with an output pin of the step-down chip U1; the capacitor C3, the capacitor C2 and the capacitor C4 are all connected in parallel between the inductor B1 and the inductor B3.

8. The dual under-voltage protection circuit of claim 1, wherein, The model of the power supply voltage detector U2 is SSP61CC3002MR.

9. The dual under-voltage protection circuit of claim 1, wherein, The under-voltage regulating unit further comprises a resistor R8 and a resistor R9 for selecting one of the two under-voltage protection points; a first end of the resistor R8 is connected to the reference voltage, a second end of the resistor R8 is connected to a first end of the resistor R9 and an input end of the power voltage detector U2; a first end of the resistor R9 is also connected to the input end of the power voltage detector U2, and a second end of the resistor R9 is grounded.

10. A power supply cord for a vehicle, characterized by comprising: The under-voltage regulating unit further comprises a resistor R8 and a resistor R9 for selecting one of the two under-voltage protection points; a first end of the resistor R8 is connected to the reference voltage, a second end of the resistor R8 is connected to a first end of the resistor R9 and an input end of the power voltage detector U2; a first end of the resistor R9 is also connected to the input end of the power voltage detector U2, and a second end of the resistor R9 is grounded.

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