Complex load slow start switching device miniaturization circuit

Abstract

The invention discloses a miniaturized circuit of a complex load slow start switching device, and relates to the technical field of electronic products. The complex load slow start switching device miniaturization circuit comprises a power supply, a power supply switch SW1, a load and a composite resistor module. The miniaturized circuit of the complex load slow-start switching device breaks through the limitation of large size of a traditional circuit in the aspect of size, and greatly reduces the size of the component through the innovative design that the NTC and the PTC resistor are connected in parallel and then connected with the power switch in series and by utilizing the complementary characteristics of the NTC and the PTC resistor. And the circuit is excellent in slow start performance. The characteristic effectively limits the starting current, prevents a switch and a load from being damaged, can reduce steady-state voltage drop and heating, and guarantees safe and stable operation of the circuit. In addition, the circuit is wide in applicability and suitable for various complex load environments.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic products, in particular to a miniaturized circuit for a complex load slow-start switch device. Background Art

[0002] In the fields of electronic product power switches, vehicle electronics, electric door locks, etc., complex loads (composed of resistive, capacitive and inductive loads) will generate very large currents at the moment of startup, while the continuous working current is relatively small.

[0003] In order to prevent the switch from burning out at the moment of startup, conventional power supply slow-start circuits usually use a pre-charge resistor in series or a pre-charge resistor controlled by a switch in parallel. However, these methods have many problems, such as the large heat generation and voltage drop of conventional series resistors when working continuously; the parallel method is not commonly used because the switch is expensive, bulky, and the control method is complicated; although a single series NTC resistor can alleviate the heat generation and voltage drop problems, it is still difficult to meet the starting current and operating current requirements under the trend of equipment miniaturization, and the volume is large. In response to the shortcomings of the existing technology, the present invention provides a miniaturized circuit for complex load slow-start switch devices to solve the above problems. Summary of the Invention

[0004] To address the shortcomings of the existing technology, the present invention provides a miniaturized circuit for complex load slow-start switching devices. This circuit overcomes the bulk limitations of conventional circuits by utilizing an innovative design that connects NTC and PTC resistors in parallel and then in series with the power switch, leveraging their complementary characteristics to significantly reduce component size. The circuit demonstrates excellent slow-start performance. This characteristic effectively limits the startup current, preventing damage to the switch and load, while also reducing steady-state voltage drop and heat generation, ensuring safe and stable circuit operation. Furthermore, the circuit is widely applicable and suitable for a variety of complex load environments.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: a miniaturized circuit of a complex load slow-start switch device, comprising a power supply, a power switch SW1, a load, and a composite resistance module; The power switch SW1 is connected in series between the power supply and the load; The composite resistor module includes an NTC resistor R1 and a PTC resistor R2 connected in parallel; The composite resistance module is connected in series with the power switch SW1; The composite resistor module is used for allowing the PTC resistor R2 to bear the main starting current and quickly heat up during the starting phase, while heating the NTC resistor R1 to reduce its resistance, and allowing the NTC resistor R1 to bear the main working current during the steady state phase.

[0006] Preferably, the composite resistance module is provided between the input end of the power switch SW1 and the positive electrode of the power supply.

[0007] Preferably, the composite resistance module is provided between the output end of the power switch SW1 and the load.

[0008] Preferably, the power switch SW1 is an electronic switch.

[0009] Preferably, the electronic switch adopts MOS with a withstand voltage of 150V and a maximum safe current of 25A.

[0010] Preferably, the normal temperature resistance of the PTC resistor R2 is smaller than the normal temperature resistance of the NTC resistor R1.

[0011] Preferably, the resistance range of the PTC resistor R2 at normal temperature is 1–10Ω, and the resistance range of the NTC resistor R1 at normal temperature is 5–20Ω.

[0012] Preferably, the circuit is suitable for an electric vehicle power supply system, with a power supply voltage range of 20–100 V, a load capacitance ≥ 1000 μF, and a steady-state operating current ≤ 1 A.

[0013] Preferably, the NTC resistor R1 is of model 12D-7, and the PTC resistor R2 is of model B1048.

[0014] Preferably, the power switch SW1 is a mechanical switch.

[0015] The present invention discloses a miniaturized circuit for a complex load slow-start switch device, which has the following beneficial effects: 1. The miniaturized circuit of the complex load slow-start switch device is composed of an NTC resistor and a PTC resistor in parallel, which are then connected in series with the power switch. By complementing the characteristics of the two resistors, the slow-start function is achieved while the size of the components is greatly reduced. Taking the electric vehicle power supply system as an example, if a conventional single NTC resistor is connected, a larger resistor is required to achieve a similar effect, which occupies a large volume. The combination of NTC resistors and PTC resistors used in the circuit of the present invention reduces the height by about half and the volume by 2.5 times. This allows the circuit to be easily integrated into various small electronic products and vehicle electronic equipment, provides strong support for the miniaturization design of the equipment, and helps to improve the market competitiveness of the product.

[0016] 2. This miniaturized circuit for complex load slow-start switching devices. During startup, the PTC resistor has a low resistance at room temperature and can carry the majority of the starting current, rapidly heating up while simultaneously heating the NTC resistor, causing it to decrease in resistance. As the capacitor rapidly charges, the PTC resistor increases and exits the current loop, while the NTC resistor further decreases in resistance, carrying the majority of the operating current. This characteristic effectively limits the startup current during startup, preventing transient current surges that could damage the switch and load. It also reduces voltage drop and heat generation during steady-state operation, improving circuit efficiency.

[0017] 3. The miniaturized circuit of the complex load slow-start switch device, the power switch can be a mechanical switch or an electronic switch, which provides greater flexibility for circuit design. Mechanical switches have a simple structure and low cost, and are suitable for cost-sensitive occasions with low control requirements; electronic switches such as MOS have the advantages of flexible control and fast response speed, and are suitable for scenarios that require precise control and fast response. At the same time, the circuit is suitable for a variety of complex load environments such as electric vehicle power systems, with a power supply voltage range of 20-100V, a load capacitance ≥1000μF, and a steady-state operating current ≤1A. Whether in the field of power switches for electronic products or electronic door locks for vehicles, they can be flexibly configured according to specific needs to meet the slow-start requirements in different application scenarios, demonstrating strong versatility and adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 Schematic diagram of the overall circuit of the present invention DETAILED DESCRIPTION

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0021] The embodiment of the present application provides a miniaturized circuit for a complex load slow-start switch device, adopts a method of connecting a switch and an NTC resistor in series, and connecting a PTC resistor in parallel next to the NTC resistor, so that the PTC resistor and the NTC resistor can jointly undertake the slow-start work. The PTC resistor has the characteristics of small resistance at room temperature and large resistance at high temperature, and the NTC resistor has the characteristics of large resistance at room temperature and small resistance at high temperature, and the two characteristics are opposite. In the startup phase, the PTC resistor bears the main starting current and heats up rapidly, while heating the NTC resistor to reduce its resistance; in the steady-state phase, the NTC resistor bears the main working current. In this way, the characteristics of large starting resistance and small working resistance are achieved, and at the same time, the starting current is large, a large starting power is achieved, and the size of the components can be made very small.

[0022] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0023] Example 1: The embodiment of the present invention discloses a miniaturized circuit for a complex load slow-start switch device. Figure 1 As shown, it includes a power supply, a power switch SW1, a load and a compound resistance module; The power switch SW1 is connected in series between the power supply and the load. This switch can be a mechanical switch or an electronic switch (such as a MOS switch) and is used to control the connection between the power supply and the load. Electronic switches offer flexible control and fast response, while mechanical switches have the advantages of simple structure and low cost.

[0024] A composite resistance module consisting of an NTC resistor R1 and a PTC resistor R2 connected in parallel; The composite resistance module is connected in series with the power switch SW1; The composite resistor module is used for allowing the PTC resistor R2 to bear the main starting current and quickly heat up during the starting phase, while heating the NTC resistor R1 to reduce its resistance, and allowing the NTC resistor R1 to bear the main working current during the steady state phase.

[0025] NTC resistor R1 has a high resistance at room temperature and a low resistance at high temperature. During the startup phase, its high resistance limits the startup current, preventing excessive transient current from burning out the switch. During the steady-state phase, its resistance decreases as temperature rises, reducing the voltage drop and heat generation during steady-state operation and improving circuit efficiency.

[0026] NTC resistor R1 and PTC resistor R2 are connected in parallel and in series with power switch SW1. During the startup phase, the PTC resistor carries the majority of the current, while heating the NTC resistor to reduce its resistance. During the steady-state phase, the NTC resistor carries the majority of the operating current.

[0027] The PTC resistor R2 has a low resistance at room temperature and a high resistance at high temperature. During the startup phase, it can bear most of the startup current. After rapidly heating up, its resistance increases, preventing itself from burning out due to excessive current and providing conditions for the resistance of the NTC resistor to decrease.

[0028] The PTC resistor R2 is connected in parallel with the NTC resistor R1, and the two together form a composite resistor module, which is connected in series with the power switch SW1 to jointly complete the slow start function.

[0029] This miniaturized circuit for complex load slow-start switches is used in an electric vehicle system powered by 24 lithium-ion batteries in series. The maximum supply voltage is 100V. SW1 uses a NCE15P25JK PMOS transistor as the power switch. This transistor has a 150V withstand voltage and a maximum safe current of 25A. In this case, the load capacitance is greater than 1000uF, and the steady-state continuous operating current is between 0.5A and 1A. R1 uses a 12D-7 NTC resistor, and R2 uses a B1048 PTC resistor.

[0030] According to the data, 12D-7 is an NTC resistor with a room temperature resistance of 12 ohms, a withstand voltage of 120V, a maximum steady-state current of 1A, a maximum load capacitance of 390uF, and a maximum diameter of 9mm.

[0031] B1048 is a PTC resistor with a resistance of 6 ohms at room temperature and a withstand voltage of 230V. Its maximum diameter is 8mm.

[0032] When the power is turned on, due to the presence of capacitor CL, the voltage across R1 and R2 is 100V. At this time, the current in the circuit is: IR1+IR2=100V / 12R+100V / 6R=8.3A+16.7A=25A The current meets the MOS safety current, and the capacitor's voltage rapidly increases. The voltage across R1 and R2 decreases rapidly. Simultaneously, due to the heating caused by the startup current, R2's resistance increases rapidly, no longer carrying the current loop. R1's resistance quickly decreases to around 0.82 ohms, becoming the primary power supply loop. The 12D-7's maximum capacitive load is 390uF, but R2 briefly provides twice that load capacity (16.7A / 8.3A=2). The circuit's actual maximum capacitive load reaches: 390uF*3=1170uF.

[0033] If you use a conventional single NTC resistor connection method, to achieve a similar effect, you need to use at least one 5D-15 NTC resistor. Figure 1 ) Its resistance is 5 ohms, the maximum capacitive load is 1800uF, and the size is 17.5mm. The instantaneous current at startup is: 100V / 5R=20A A model that is one size smaller may not meet the capacitance or current requirements.

[0034] The height of 5D-15 is 17.5mm and the thickness is 6mm. The volume occupied is: (17.5mm / 2)^2*3.14*6mm=1442mm^3 The height of 12D-7 is 9mm and the thickness is 5mm. The height of B1048 is 8mm and the thickness is 5mm. The volume is: (9mm / 2)^2*3.14*5mm+(8mm / 2)^2*3.14*5mm=569mm^3 The improved circuit reduces the height by about half (17.5mm / 9mm=1.9) and the volume by 2.5 times (1442mm^3 / 569mm^3=2.53). The composite resistor module is positioned between the input of the power switch SW1 and the positive terminal of the power supply. At the moment of circuit startup, a large startup current is generated due to the presence of load capacitance. Positioning the composite resistor module before the power switch can proactively limit this startup current. PTC resistor R2 has a low resistance at room temperature and can quickly absorb the majority of the startup current and heat up, while simultaneously heating NTC resistor R1 and reducing its resistance. This effectively prevents the power switch from being impacted by excessive transient current, protecting the switch from burnout.

[0035] The composite resistor module is placed between the output of the power switch SW1 and the load. During startup, the PTC resistor R2 responds quickly, carrying the majority of the startup current and heating up, thereby heating the NTC resistor R1 and reducing its resistance. This configuration allows for more direct control of current fluctuations at the load end. As the load capacitor charges, the composite resistor module effectively suppresses the startup current peak, preventing damage to the load device.

[0036] The electronic switch uses a MOS with a withstand voltage of 150V and a maximum safe current of 25A. In the electric vehicle power supply system, the power supply voltage range is 20-100V. The MOS with a withstand voltage of 150V can ensure that it will not be damaged due to excessive voltage in the event of voltage fluctuations or instantaneous overvoltage. The maximum safe current of 25A can meet the current requirements of the circuit during startup and steady-state operation. During the startup phase, although the instantaneous current is large, the safe current range of the MOS can ensure its normal operation. When the steady-state operating current is ≤1A, the MOS can operate stably and has a certain margin, thereby improving the reliability of the circuit. At the same time, this specification of MOS has good conduction characteristics and switching characteristics, which can reduce the conduction voltage drop and switching loss, and improve the circuit efficiency.

[0037] The room temperature resistance of the PTC resistor R2 is smaller than the room temperature resistance of the NTC resistor R1. During the startup phase, the room temperature resistance of the PTC resistor R2 is small, and it can quickly bear most of the startup current, allowing the capacitor to charge quickly. At the same time, the heat generated by it heats the NTC resistor R1, reducing its resistance. This combination of characteristics ensures that the current will not be too large at the moment of startup, protecting the power switch and the load. For example, in an electric vehicle system powered by 24 lithium batteries in series, the instantaneous current is large during startup, and the low resistance characteristic of the PTC resistor R2 can effectively share the current and avoid current concentration causing damage to other components. In the steady-state phase, the resistance of the NTC resistor R1 decreases, bearing the main working current to ensure the normal operation of the circuit.

[0038] The resistance range of the PTC resistor R2 at room temperature is 1–10Ω, and the resistance range of the NTC resistor R1 at room temperature is 5–20Ω. This resistance range is reasonable. The resistance range of the PTC resistor R2 ensures that the startup current can be quickly absorbed during the startup phase and can be reasonably selected based on the actual circuit requirements. For example, in a circuit with small load capacitance and low startup current requirements, a PTC resistor with a larger resistance at room temperature can be selected; in a circuit with large load capacitance and requiring rapid charging, a PTC resistor with a smaller resistance at room temperature can be selected. The resistance range of the NTC resistor R1 can effectively reduce voltage drop and heat generation during the steady-state phase. When the steady-state operating current is ≤1A, the appropriate NTC resistor value can ensure circuit efficiency while providing a stable current supply under different power supply voltage and load conditions.

[0039] This circuit is suitable for electric vehicle power systems. It requires a power supply voltage range of 20–100V, a load capacitance of 1000μF or greater, and a steady-state operating current of 1A or less. While power supply voltages may vary across different electric vehicle models and configurations, a 20-100V supply voltage range satisfies most electric vehicle needs. A load capacitance of 1000μF or greater ensures sufficient energy during startup, allowing the load to start quickly.

[0040] The NTC resistor R1 is model 12D-7, and the PTC resistor R2 is model B1048. The 12D-7 NTC resistor has specific parameters, including room-temperature resistance, withstand voltage, maximum steady-state current, and maximum load capacitance, to meet the circuit's current supply and capacitive load requirements during steady-state operation. Its relatively small maximum diameter, 9mm, facilitates circuit miniaturization. The B1048 PTC resistor has a room-temperature resistance of 6Ω, a withstand voltage of 230V, and a maximum diameter of 8mm. It can effectively handle the startup current and rapidly heat up during startup.

[0041] In summary, the traditional power supply slow start circuit has the problem of being too large due to the use of a single resistor or a complex parallel switch control method, which makes it difficult to meet the needs of equipment miniaturization. The composite resistor module of the present invention is composed of an NTC resistor and a PTC resistor in parallel, which are then connected in series with the power switch. By complementing the characteristics of the two resistors, the size of the components is greatly reduced while achieving the slow start function. Taking the electric vehicle power supply system as an example, using the conventional single NTC resistor connection method, a larger resistor is required to achieve a similar effect, which occupies a large volume; while the combination of NTC resistors and PTC resistors used in the circuit of the present invention reduces the height by about half and the volume by 2.5 times. This allows the circuit to be easily integrated into various small electronic products and vehicle electronic equipment, provides strong support for the miniaturization design of equipment, and helps to improve the market competitiveness of products.

[0042] The instantaneous current at the start of complex loads is extremely large, and it is very easy to burn out the switch. The composite resistor module of the present invention cleverly solves this problem. During startup, the PTC resistor has a small resistance at room temperature, can bear most of the starting current and heat up quickly, and at the same time heats the NTC resistor to reduce its resistance. As the capacitor charges rapidly, the resistance of the PTC resistor increases and exits the current loop, and the resistance of the NTC resistor further decreases, bearing the main working current. This characteristic enables the circuit to effectively limit the starting current during the startup phase, preventing excessive instantaneous current from damaging the switch and load; in the steady-state phase, it can reduce voltage drop and heat generation, thereby improving circuit efficiency. For example, in an electric vehicle system powered by 24 lithium batteries, the circuit successfully achieves effective control of the starting current and a stable supply of working current, ensuring the safe and stable operation of the circuit.

[0043] The power switch of the present invention can be a mechanical switch or an electronic switch, which provides greater flexibility for circuit design. Mechanical switches have a simple structure and low cost, and are suitable for cost-sensitive occasions and low control requirements; electronic switches such as MOS have the advantages of flexible control and fast response speed, and are suitable for scenarios that require precise control and fast response. At the same time, the circuit is suitable for a variety of complex load environments such as electric vehicle power systems, with a power supply voltage range of 20-100V, a load capacitance ≥1000μF, and a steady-state operating current ≤1A. Whether in the field of power switches for electronic products or electronic door locks for vehicles, they can be flexibly configured according to specific needs to meet the slow start requirements in different application scenarios, showing strong versatility and adaptability.

[0044] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0045] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A miniaturized circuit for a complex load slow-start switch device, characterized in that: Includes power supply, power switch SW1, load and compound resistance module; The power switch SW1 is connected in series between the power supply and the load; The composite resistor module includes an NTC resistor R1 and a PTC resistor R2 connected in parallel; The composite resistance module is connected in series with the power switch SW1; The composite resistor module is used for allowing the PTC resistor R2 to bear the main starting current and quickly heat up during the starting phase, while heating the NTC resistor R1 to reduce its resistance, and allowing the NTC resistor R1 to bear the main working current during the steady state phase.

2. A miniaturized circuit for a complex load slow-start switch device according to claim 1, characterized in that: The composite resistance module is arranged between the input end of the power switch SW1 and the positive electrode of the power supply.

3. The miniaturized circuit of a complex load slow-start switch device according to claim 1, characterized in that: The composite resistance module is arranged between the output end of the power switch SW1 and the load.

4. The miniaturized circuit of a complex load slow-start switch device according to claim 1, characterized in that: The power switch SW1 is an electronic switch.

5. The miniaturized circuit of a complex load slow-start switch device according to claim 4, characterized in that: The electronic switch adopts MOS with a withstand voltage of 150V and a maximum safe current of 25A.

6. The miniaturized circuit of a complex load slow-start switch device according to claim 1, characterized in that: The normal temperature resistance of the PTC resistor R2 is smaller than the normal temperature resistance of the NTC resistor R1.

7. A miniaturized circuit for a complex load slow-start switch device according to claim 6, characterized in that: The resistance range of the PTC resistor R2 at room temperature is 1–10Ω, and the resistance range of the NTC resistor R1 at room temperature is 5–20Ω.

8. The miniaturized circuit of a complex load slow-start switch device according to claim 1, characterized in that: The circuit is suitable for electric vehicle power supply systems with a power supply voltage range of 20–100 V, a load capacitance ≥ 1000 μF, and a steady-state operating current ≤ 1 A.

9. The miniaturized circuit of a complex load slow-start switch device according to claim 1, characterized in that: The NTC resistor R1 is of model 12D-7, and the PTC resistor R2 is of model B1048.

10. The miniaturized circuit of a complex load slow-start switch device according to claim 1, characterized in that: The power switch SW1 is a mechanical switch.

Images