Low temperature heating circuit heating control method

Abstract

The application relates to a low-temperature heating circuit heating control method, which uses a low-temperature heating circuit system to perform heating control; the system comprises a main heating module, an auxiliary heating module, a first and a second voltage reduction chip. The method comprises the following steps: when the temperature of a to-be-heated circuit is -40 DEG C, two power switches are simultaneously turned on, and two power resistors are simultaneously heated; when the temperature is raised to above 0 DEG C, the first power switch continues to work, the second power switch is turned off, and the to-be-heated circuit is powered on to work; when the temperature is raised to above 5 DEG C, both of the power switches are turned off, and the to-be-heated circuit is maintained to work normally. The core advantage of the application is that the application is free from the dependence on a temperature sensor and an MCU / CPU, and brings a wider space for chip application; the application can make chips originally unable to work normally in a -40 DEG C environment, such as consumer-grade or wide-temperature-grade chips, successfully applied in an extreme environment of low temperature -40 DEG C, and the application effectively solves the limitation problem of chip selection.

Description

Technical Field

[0001] This application relates to the field of intelligent heating and temperature control of circuit systems, and in particular to a heating control method for a low-temperature heating circuit. Background Technology

[0002] In current circuit heating control technology, the industry mostly adopts a collaborative approach between temperature sensors and MCU / CPU to control the heating circuit's on / off state. However, this approach has significant drawbacks. When there is no MCU, or the MCU itself malfunctions, the chip to be heated may fail to heat in low-temperature environments, or the heating circuit may fail to shut off at high temperatures. This not only wastes power but, more seriously, can lead to system malfunctions due to overheating, and even safety issues.

[0003] Currently, the heating circuit is typically controlled by a temperature sensor to turn on and by the CPU to turn off. However, the CPU is a relatively faulty component. Faults in components such as DDR, eMMC, or power supply can cause the CPU to malfunction or even crash. If the CPU experiences such a problem, it will be unable to accurately output GPIO signals to turn off the heating resistor, causing the heating circuit to continue operating, generating excessive heat, damaging the chip, and posing a serious safety hazard.

[0004] In the application scenario mentioned in CN201910832622.3, during low-temperature startup, the temperature sensor detects the ambient temperature after the system powers on. When the ambient temperature is -25℃ or below, the temperature sensor outputs a logic high level; under normal temperature conditions, it outputs a logic low level. The high-power MOS switching circuit controls the opening and closing of the heating circuit based on the temperature sensor output level. However, if the CPU malfunctions, the subsequent step of controlling the heating circuit to shut down via the GPIO port will fail. The existing technology's reliance on temperature sensors and MCU / CPU significantly reduces the robustness of the entire system in heating control, failing to fully guarantee the stable and safe operation of the system under complex working conditions. Summary of the Invention

[0005] In view of this, this application proposes a heating control method for a low-temperature heating circuit, which uses a low-temperature heating circuit system for heating control. The low-temperature heating circuit system includes a main heating module, an auxiliary heating module, a first step-down chip, and a second step-down chip. The main heating module includes a first thermistor, a first comparator, a first power switch, and a first power resistor.

[0006] The output of the first comparator is connected to the control terminal of the first power switch. One end of the first power switch is connected to the power supply, and the other end is connected to the first power resistor. The first power resistor is used to heat the circuit to be heated.

[0007] The auxiliary heating module includes a second thermistor, a second comparator, a second power switch, and a second power resistor;

[0008] The output of the second comparator is connected to the control terminal of the second power switch. One end of the second power switch is connected to the power supply, and the other end is connected to the second power resistor. The second power resistor is used to heat the circuit to be heated.

[0009] The first step-down chip provides power to the low-temperature heating circuit system, and the second step-down chip, controlled by the second comparator, provides power to the circuit to be heated.

[0010] The methods include:

[0011] When the temperature of the circuit to be heated is -40℃, the first power switch and the second power switch are turned on simultaneously, and heating is provided to the circuit to be heated through the first power resistor and the second power resistor.

[0012] When the temperature of the circuit to be heated rises above 0°C, the first power switch continues to work, the second power switch is turned off, and the circuit to be heated is powered on and begins to work.

[0013] When the temperature of the circuit to be heated rises above 5°C, both the first power switch and the second power switch are turned off, and the circuit to be heated maintains normal operation.

[0014] In one possible implementation, the method further includes:

[0015] When the temperature of the circuit to be heated drops from 5℃ to below -5℃, the first power switch is turned on and the second power switch remains closed, and the circuit to be heated continues to work in the heating state.

[0016] When the temperature of the circuit to be heated rises from -5℃ to above 5℃, the first power switch and the second power switch turn off again, and the circuit continues to work. Thereafter, the first power switch cycles on and off between 5℃ and -5℃ depending on the temperature of the circuit to be heated, while the second power switch always remains off, so that the operating temperature of the circuit to be heated is maintained between -5℃ and 5℃.

[0017] In one possible implementation, when the ambient temperature rises above 5°C and the temperature of the circuit to be heated simultaneously reaches above 5°C, both the first power switch and the second power switch remain off, and the first power switch no longer automatically turns on until the ambient temperature and the temperature of the circuit to be heated fall below -5°C again, at which point the first power switch turns on again.

[0018] In one possible implementation, the first comparator compares the voltage of the first thermistor at the non-inverting input with the first reference voltage at the inverting input. When the voltage of the first thermistor at the non-inverting input is greater than the first reference voltage at the inverting input, it outputs a high level, and when the voltage of the first thermistor at the non-inverting input is less than the first reference voltage at the inverting input, it outputs a low level.

[0019] The second comparator compares the voltage of the second thermistor at the non-inverting input with the second reference voltage at the inverting input. When the voltage of the second thermistor at the non-inverting input is greater than the second reference voltage at the inverting input, it outputs a high level; when the voltage of the second thermistor at the non-inverting input is less than the second reference voltage at the inverting input, it outputs a low level.

[0020] In one possible implementation, the connection and disconnection of the first power switch depends on a signal generated by a first comparator, and the connection and disconnection of the second power switch depends on a signal generated by a second comparator.

[0021] In one possible implementation, when the temperature of the circuit to be heated decreases from -40°C to -5°C, the first comparator obtains a voltage drop greater than its reference voltage through the first thermistor, and the first comparator outputs a high level. After being inverted by the first transistor, the first power switch is turned on. The second comparator obtains a voltage drop greater than its reference voltage through the second thermistor, and the second comparator outputs a high level. After being inverted by the second transistor, the second power switch is turned on.

[0022] When the temperature of the circuit to be heated increases from -5℃ to 0℃, a comparator obtains a voltage drop through the first thermistor, but it is still greater than its reference voltage. The first comparator outputs a high level, which is inverted by the first transistor, and the first power switch is turned on. The second comparator obtains a voltage drop through the second thermistor, which is less than its reference voltage. The second comparator outputs a low level, which is inverted by the second transistor, and the second power switch is turned off, and the circuit to be heated begins to work.

[0023] When the temperature of the circuit to be heated increases from 0℃ to 5℃, the first comparator obtains a voltage drop through the first thermistor that is less than its reference voltage. The first comparator outputs a low level, which is then inverted by the first transistor, and the first power switch is turned off. The second comparator obtains a voltage drop through the second thermistor that is less than its reference voltage. The second comparator outputs a low level, which is then inverted by the second transistor, and the second power switch is turned off, allowing the circuit to be heated to continue operating.

[0024] In one possible implementation, when the temperature of the circuit to be heated drops from 5°C to 0°C, the first comparator obtains a voltage drop less than its reference voltage through the first thermistor, and the first comparator outputs a low level. After being inverted by the first transistor, the first power switch is turned off. The second comparator obtains a voltage drop less than its reference voltage through the second thermistor, and the second comparator outputs a low level. After being inverted by the second transistor, the second power switch is turned off, and the circuit to be heated continues to operate.

[0025] When the temperature of the circuit to be heated drops to -5℃, the first comparator obtains a voltage drop greater than its reference voltage through the first thermistor, and the first comparator outputs a high level. After being inverted by the first transistor, the first power switch is turned on. The second comparator obtains a voltage drop less than its reference voltage through the second thermistor, and the second comparator outputs a high level. After being inverted by the second transistor, the second power switch is turned off, and the circuit to be heated continues to operate.

[0026] When the temperature of the circuit to be heated rises to 5℃, the first comparator obtains a voltage drop through the first thermistor that is less than its reference voltage, and the first comparator outputs a low level. After being inverted by the first transistor, the first power switch is turned off. The second comparator obtains a voltage drop through the second thermistor that is less than its reference voltage, and the second comparator outputs a low level. After being inverted by the second transistor, the second power switch is turned off, and the circuit to be heated continues to operate.

[0027] In one possible implementation, when the temperature of the circuit to be heated rises to 5°C, the first comparator obtains a voltage drop less than its reference voltage through the first thermistor, and the first comparator outputs a low level. After being inverted by the first transistor, the first power switch is turned off. The second comparator obtains a voltage drop less than its reference voltage through the second thermistor, and the second comparator outputs a low level. After being inverted by the second transistor, the second power switch is turned off, and the circuit to be heated continues to operate.

[0028] The method includes the following steps: when the temperature of the circuit to be heated drops to -5℃, the first comparator obtains a voltage division greater than its reference voltage through the first thermistor, and the first comparator outputs a high level. After being inverted by the first transistor, the first power switch is turned on. The second comparator obtains a voltage division less than its reference voltage through the second thermistor, and the second comparator outputs a low level. After being inverted by the second transistor, the second power switch is turned off, and the circuit to be heated continues to operate.

[0029] When the temperature of the circuit to be heated rises to 5°C, the first comparator obtains a voltage drop through the first thermistor that is less than its reference voltage. The first comparator outputs a low level, which is then inverted by the first transistor, and the first power switch is turned off. The second comparator obtains a voltage drop through the second thermistor that is less than its reference voltage. The second comparator outputs a low level, which is then inverted by the second transistor, and the second power switch is turned off, allowing the circuit to be heated to continue operating.

[0030] The beneficial effects of this invention are:

[0031] The core advantage of this invention lies in eliminating the reliance on temperature sensors and MCUs / CPUs, thus opening up a wider range of chip applications. It enables consumer-grade or wide-temperature-range chips, which were previously unable to operate normally in -40°C environments, to be successfully used in extreme environments. This feature effectively solves the limitation problem of chip selection. Previously, low-temperature applications often required expensive dedicated chips, while this invention allows for the use of more conventional chips, significantly reducing selection costs.

[0032] Other features and aspects of this application will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0033] The accompanying drawings, which are included in and form part of this specification, illustrate exemplary embodiments, features, and aspects of this application together with the specification and serve to explain the principles of this application.

[0034] Figure 1 This diagram shows the main structure of a low-temperature heating circuit system device according to an embodiment of this application;

[0035] Figure 2 A flowchart illustrating the operation of a low-temperature heating circuit system device according to an embodiment of this application is shown.

[0036] Figure 3 This invention provides a voltage divider flowchart of a cryogenic heating circuit system device according to an embodiment of the present application.

[0037] Figure 4 The diagram shows the characteristic relationship between the input voltage divider and the output of the reference voltage 1 and reference voltage 2 of this application. Detailed Implementation

[0038] Various exemplary embodiments, features, and aspects of this application will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0039] It should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the present invention or simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0040] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0041] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0042] Furthermore, to better illustrate this application, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this application can be implemented without certain specific details. In some instances, methods, means, components, and circuits well-known to those skilled in the art have not been described in detail in order to highlight the main points of this application.

[0043] The invention of this application is a heating control method for a low-temperature heating system circuit, which is applied in the field / equipment of intelligent heating and temperature control of circuit systems, and plays a role in intelligent heating and temperature control of chips such as MCU / CPU.

[0044] Heating circuit

[0045] specifically refer to Figure 1 , Figure 1 This diagram illustrates the main structure of a low-temperature heating circuit system device according to an embodiment of this application. The low-temperature heating circuit system device includes a main heating module, an auxiliary heating module, a first step-down chip DC-DC1, and a second step-down chip DC-DC2.

[0046] The first step-down chip, DC-DC1, provides power to the low-temperature heating circuit system, while the second step-down chip, DC-DC2, controlled by the second comparator, provides power to the circuit to be heated. The circuit power supply provides a wide input range of 9-36V. After being stepped down by the first step-down chip, DC-DC1, it powers the low-temperature heating circuit, and after being stepped down by the second step-down chip, DC-DC2, it powers the circuit to be heated.

[0047] The main heating module includes a first thermistor RT1, a first comparator, a first transistor, a first power switch MOS1, and a first power resistor *M. The output of the first comparator is connected to the control terminal of the first power switch MOS1 via the first transistor. One end of the first power switch MOS1 is connected to the power supply, and the other end is connected to the first power resistor *M. The main heating module provides the primary heat source for the circuit to be heated. At low temperatures, the resistance of the first thermistor RT1 changes, which controls the first power switch MOS1 to conduct through the first comparator, causing the first power resistor *M to heat up and provide the main heat, meeting the requirements for conventional low-temperature heating.

[0048] The auxiliary heating module includes a second thermistor RT2, a second comparator, a second transistor, a second power switch MOS2, and a second power resistor *N. The output of the second comparator is connected to the control terminal of the second power switch MOS2 via the second transistor. One end of the second power switch MOS2 is connected to the power supply, and the other end is connected to the second power resistor *N. The auxiliary heating module is used to provide a secondary heat source for the circuit to be heated at extreme temperatures. At extremely low temperatures, the resistance of the second thermistor RT2 changes, which controls the second power switch MOS2 to conduct via the second comparator. The second power resistor *N then provides auxiliary heat, ensuring system operation under extreme conditions.

[0049] The low-temperature heating circuit system compares the voltage division values ​​between negative temperature thermistors with the reference voltages of their respective comparators. Based on the comparison result signal output by the comparators, it controls the switching of the power resistors to achieve the activation of low-temperature heating, the activation of the auxiliary heating module, and the automatic shutdown of room temperature and high-temperature heating. When the temperature decreases, the resistance of the thermistors increases, interacting with the voltage divider circuit to raise the voltage at the comparator input. When the voltage exceeds a preset threshold, the comparator outputs a high level, which, after being inverted by the corresponding first and second transistors, turns on the power switch, starting heating. When the temperature increases, the resistance of the thermistors decreases, and the voltage at the comparator input drops below the threshold. When this voltage drops, the comparator outputs a low level, turning off the power switch and stopping heating.

[0050] In one possible implementation, the power supply to the auxiliary heating module and the circuit to be heated are mutually exclusive, ensuring that the system is powered at a suitable temperature.

[0051] Preferably, a negative temperature coefficient (NTC) thermistor is used. NTC thermistors have high temperature sensitivity, fast response, and their resistance changes exponentially with temperature, exhibiting good linearity. They are suitable for accurately detecting minute temperature changes and are ideal for precision temperature measurement applications.

[0052] In one possible implementation, the main heating module includes a first voltage divider circuit. The output of the first voltage divider circuit is connected to the input of a first comparator, which converts temperature changes into voltage signals and inputs them to the first comparator to provide a basis for the comparator to determine whether to start heating.

[0053] In one possible implementation, the auxiliary heating module includes a second voltage divider circuit. The output of the second voltage divider circuit is connected to the input of a second comparator, and the output voltage signal is given to the second comparator. At the same time, the output signal of the second comparator controls the base of the third transistor, thereby controlling the EN of the second buck chip DCDC2 to achieve power supply control.

[0054] In one possible implementation, the second buck chip DC-DC2 includes a third transistor, which is used to invert the output signal of the second comparator. The base of the third transistor is connected to the output terminal of the second comparator, and the EN terminal of the second buck chip DC-DC2 is connected to the collector of the third transistor.

[0055] In one possible implementation, the first voltage divider circuit includes resistors R1, R2, R3, R4, and RT1, and the second voltage divider circuit includes resistors R5, R6, R7, R8, and RT2. The first voltage divider circuit is connected to the inverting input of the first comparator via resistor R1 and to the non-inverting input via resistors R3 and RT1. The second voltage divider circuit is connected to the inverting input of the second comparator via resistor R5 and to the non-inverting input via resistors R7 and RT2.

[0056] In one specific embodiment, the voltage divider circuit composed of R1, R2, R3, R4, and RT1 includes resistors R1, R2, R3, R4, and a first thermistor RT1. One end of R1 and R3 is connected to the 5V power supply line output by the first step-down chip. The other end of R1 is connected to the reference voltage I input port of the first comparator; the other end of R3 is connected to the first thermistor RT1. The other end of the first thermistor RT1 is connected to R4, and the other end of R4 is grounded. One end of R2 is connected to the reference voltage I input port of the first comparator, and the other end is grounded, providing a comparison reference signal for it.

[0057] In one specific embodiment, the voltage divider circuit composed of R5, R6, R7, R8, and RT2 includes resistors R5, R6, R7, R8, and a second thermistor RT2. One end of R5 and R7 is connected to a 5V power supply line. The other end of R5 is connected to the reference voltage input 2 of the second comparator; the other end of R7 is connected to the second thermistor RT2. The other end of the second thermistor RT2 is connected to R8, and the other end of R8 is grounded. One end of R6 is connected to the reference voltage input 2 of the second comparator, and the other end is grounded, providing a comparison reference signal.

[0058] In one possible implementation, the connection line between the output of the first comparator and the control terminal of the first power switch MOS1 includes a first pull-up resistor R11, and the connection line between the output of the second comparator and the control terminal of the second power switch MOS2 includes a second pull-up resistor R12. The first pull-up resistor R11 and the second pull-up resistor R12 respectively ensure that when the outputs of the first and second comparators are high, they reliably drive the first power switch to conduct after passing through the first transistor connected to the output of the first comparator, and drive the second power switch to conduct after passing through the second transistor connected to the output of the second comparator, thus ensuring the normal startup of the heating function.

[0059] In one possible implementation, the main heating module further includes a first feedback circuit, and the auxiliary heating module further includes a second feedback circuit. In a specific embodiment, the first feedback circuit includes a resistor R9, and the second feedback circuit includes a resistor R10. One end of resistor R9 is connected to a first pull-up resistor R11, and the other end is connected to a first voltage divider circuit. Specifically, it is connected to one end of resistor R4 in the voltage divider circuit. One end of resistor R10 is connected to a second pull-up resistor R12, and the other end is connected to a second voltage divider circuit, specifically connected to one end of resistor R8 in the voltage divider circuit, forming a hysteresis comparison characteristic to enhance circuit stability.

[0060] In one possible implementation, the first power switch MOS1 is a PMOS transistor, and the second power switch MOS2 is a PMOS transistor. MOS transistors have the characteristics of fast switching speed and low on-resistance, and as power switches, they can achieve fast response and low power consumption operation of the heating circuit. Specifically, the first power switch MOS1 is a PMOS transistor, and the second power switch MOS2 is a PMOS transistor.

[0061] In one possible implementation, a first transistor is connected between the output of the first comparator and the first power switch MOS1, and a second transistor is connected between the output of the second comparator and the second power switch MOS2. The first transistor is used to invert the signal output by the first comparator, and the second transistor is used to invert the signal output by the second comparator.

[0062] In one possible implementation, a pull-up resistor is connected between the power input terminal and the EN terminal of the first buck chip DC-DC1, so that the EN terminal is in a high-level enabled state by default, enabling the first buck chip DC-DC1 to operate and supply power to the low-temperature heating circuit.

[0063] In one possible implementation, the source of the first power switch MOS1 and the source of the second power switch MOS2 are both connected to the power supply terminal.

[0064] In one possible implementation, the second power switch MOS2 and the second buck converter DCDC2 are mutually exclusive. This ensures that the circuit to be heated is not powered when the auxiliary heating module is working, and is only powered when the auxiliary heating module is not working, with the heat generated by the power supply to the circuit to replace the auxiliary heating module. This mutual exclusion design prevents the auxiliary heating module and the circuit to be heated from working simultaneously, preventing accidental power supply to the circuit under extreme low temperatures. When the auxiliary heating module is working, it ensures that the system focuses on heating; when not working, it uses its own heat to maintain the temperature, improving energy efficiency, simplifying control logic, and ensuring stable system operation in low-temperature scenarios.

[0065] In one possible implementation, the output of the second buck converter chip DC-DC2 is connected to the power supply of the module to be heated. The mutual exclusion between the second power switch MOS2 and the second buck converter chip DC-DC2 ensures that the circuit to be heated operates at a suitable temperature.

[0066] In one possible implementation, the first power resistor *M provides a heat output of 0.5-20W to meet the normal heating requirements of the main heating module.

[0067] In one possible implementation, the second power resistor *N provides 0.5-10W of auxiliary heat to work in conjunction with the main heating module at extremely low temperatures to avoid excessive energy consumption.

[0068] In one possible implementation, RT1 and RT2 are placed close to the periphery of the circuit to be heated.

[0069] In one possible implementation, the first step-down chip DC-DC1 includes an EN input port, a first power switch MOS1 outputs 12V_heat1 (main heating power supply), a first comparator outputs a Heat_Ctl (main heating control) signal to a first transistor, a third transistor is connected to the EN input port of the second step-down chip DC-DC2, the second power switch MOS2 outputs 12V_Heat2 (auxiliary heating power supply) to a second power resistor *N, the second comparator outputs a Pwr_Ctl (auxiliary heating control) signal to the third transistor and the second transistor, and the Pwr_Ctl (auxiliary heating control) signal controls the power supply to the auxiliary heating and the circuit to be heated.

[0070] In one possible implementation, the first comparator compares the voltage of the first thermistor at the non-inverting input with the first reference voltage at the inverting input. When the voltage of the first thermistor at the non-inverting input is greater than the first reference voltage at the inverting input, it outputs a high level, and when the voltage of the first thermistor at the non-inverting input is less than the first reference voltage at the inverting input, it outputs a low level.

[0071] The second comparator compares the voltage of the second thermistor at the non-inverting input with the second reference voltage at the inverting input. When the voltage of the second thermistor at the non-inverting input is greater than the second reference voltage at the inverting input, it outputs a high level; when the voltage of the second thermistor at the non-inverting input is less than the second reference voltage at the inverting input, it outputs a low level.

[0072] In one possible implementation, the connection and disconnection of the first power switch depends on a signal generated by a first comparator, and the connection and disconnection of the second power switch depends on a signal generated by a second comparator.

[0073] Control methods

[0074] In one possible implementation, when the temperature of the circuit to be heated decreases from -40°C to -5°C, the first comparator obtains a voltage drop greater than its reference voltage through the first thermistor, outputs a high level, and the first power switch is turned on; the second comparator obtains a voltage drop greater than its reference voltage through the second thermistor, outputs a high level, and the second power switch is turned on. When the temperature of the circuit to be heated decreases from -5°C to 0°C, the first comparator obtains a voltage drop less than its reference voltage through the first thermistor, but still greater than its reference voltage, outputs a high level, and the first power switch is turned on; the second comparator obtains a voltage drop less than its reference voltage through the second thermistor, outputs a low level, and the second power switch is turned off, and the circuit to be heated begins to operate. When the temperature of the circuit to be heated decreases from 0°C to 5°C, the first comparator obtains a voltage drop less than its reference voltage through the first thermistor, outputs a low level, and the first power switch is turned off; the second comparator obtains a voltage drop less than its reference voltage through the second thermistor, outputs a low level, and the second power switch is turned off, and the circuit to be heated continues to operate.

[0075] In one possible implementation, the method further includes the following steps: When the temperature of the circuit to be heated decreases from 5°C to 0°C; the first comparator obtains a voltage drop through the first thermistor that is less than its reference voltage, outputs a low level, and the first power switch is turned off; the second comparator obtains a voltage drop through the second thermistor that is less than its reference voltage, outputs a low level, and the second power switch is turned off, and the circuit to be heated continues to operate. When the temperature of the circuit to be heated decreases to -5°C; the first comparator obtains a voltage drop through the first thermistor that is greater than its reference voltage, outputs a high level, and the first power switch is turned on; the second comparator obtains a voltage drop through the second thermistor that is less than its reference voltage, outputs a high level, and the second power switch is turned off, and the circuit to be heated continues to operate. When the temperature of the circuit to be heated increases to 5°C; the first comparator obtains a voltage drop through the first thermistor that is less than its reference voltage, outputs a low level, and the first power switch is turned off; the second comparator obtains a voltage drop through the second thermistor that is less than its reference voltage, outputs a low level, and the second power switch is turned off, and the circuit to be heated continues to operate.

[0076] In one possible implementation, when the temperature of the circuit to be heated rises to 5°C; the first comparator obtains a voltage drop through the first thermistor that is less than its reference voltage, the first comparator outputs a low level, and the first power switch is turned off; the second comparator obtains a voltage drop through the second thermistor that is less than its reference voltage, the second comparator outputs a low level, the second power switch is turned off, and the circuit to be heated continues to operate. The method also includes the following steps: when the temperature of the circuit to be heated drops to -5°C; the first comparator obtains a voltage drop through the first thermistor that is greater than its reference voltage, the first comparator outputs a high level, and the first power switch is turned on; the second comparator obtains a voltage drop through the second thermistor that is less than its reference voltage, the second comparator outputs a low level, the second power switch is turned off, and the circuit to be heated continues to operate, and the above steps are repeated.

[0077] In one possible implementation, such as Figure 1 As shown, when the circuit to be heated is at -40℃, in a specific embodiment, the initial circuit to be heated and the thermistor are at -40℃, and the resistance of the first thermistor RT1 is very large. At this time, the voltage division of RT1 and R4 is greater than the reference voltage of the first comparator, i.e., reference voltage 1. At this time, the first comparator outputs a high level, that is, the main heating control signal is 1, the first power switch MOS1 is turned on, the first power resistor *M is heated, and the circuit to be heated is heated.

[0078] Similar to the main heating module, when in an environment of -40℃, the resistance of the second thermistor RT2 is very large. At this time, the voltage division of RT2 and R8 is greater than the reference voltage of the second comparator, i.e., reference voltage 2. At this time, the second comparator outputs a high level, that is, the auxiliary heating control signal is 1. The second power switch MOS2 is turned on, and the second power resistor *N heats up, heating the circuit to be heated.

[0079] When the temperature of the circuit to be heated is greater than -40℃ and less than or equal to -5℃, in a specific embodiment, the initial temperature of the circuit to be heated and the thermistor are in the range of -40℃ to -5℃. When the temperature rises from -40℃ to -5℃, the resistance of the first thermistor RT1 decreases due to the temperature. However, at this time, the voltage division of RT1 and R4 is still greater than the reference voltage of the first comparator, i.e., the reference voltage 1. At this time, the first comparator outputs a high level, that is, the main heating control signal is 1, the first power switch MOS1 is turned on, and the first power resistor *M continues to heat the circuit to be heated.

[0080] Similar to the main heating module, when the temperature rises from -40℃ to -5℃, the resistance of the second thermistor RT2 decreases as the temperature increases. However, the voltage division between RT2 and R8 is still greater than the reference voltage of the second comparator, i.e., reference voltage 2. At this time, the second comparator outputs a high level, i.e., the auxiliary heating control signal is 1. The second power switch MOS2 is turned on, and the second power resistor *N continues to heat the circuit to be heated.

[0081] When the temperature of the circuit to be heated is greater than -5℃ and less than or equal to 0℃, in a specific embodiment, the initial temperature of the circuit to be heated and the thermistor are in the range of -5℃ to 0℃. When the temperature rises from -5℃ to 0℃, the temperature increases and the resistance of the first thermistor RT1 decreases. However, at this time, the voltage division of RT1 and R4 is still greater than the reference voltage of the first comparator, i.e., the reference voltage 1. At this time, the first comparator outputs a high level, that is, the main heating control signal is 1, the first power switch MOS1 is turned on, and the first power resistor *M continues to heat the circuit to be heated.

[0082] When the temperature rises from -5℃ to 0℃, the resistance of the second thermistor RT2 decreases. The voltage drop across RT2 and R8 is less than the reference voltage (reference voltage 2) of the second comparator. At this time, the second comparator outputs a low level, meaning the auxiliary heating control signal is 0. The second power switch MOS2 is turned off, and the second power resistor *N stops heating. In response to the low level output of the second comparator, the second step-down chip DC-DC2 turns on, and the heating circuit begins to operate.

[0083] When the temperature of the circuit to be heated is greater than 0°C and less than or equal to 5°C, in a specific embodiment, the initial temperature of the circuit to be heated and the thermistor are in the range of 0°C to 5°C. When the temperature rises from 0°C to 5°C, the resistance of the first thermistor RT1 decreases. At this time, the voltage division of RT1 and R4 is less than the reference voltage of the first comparator, i.e., the reference voltage 1. At this time, the first comparator outputs a low level, that is, the main heating control signal is 0, the first power switch MOS1 is turned off, and the first power resistor *M stops heating.

[0084] When the temperature rises from 0℃ to 5℃, the resistance of the second thermistor RT2 decreases. The voltage drop across RT2 and R8 is less than the reference voltage (reference voltage 2) of the second comparator. At this point, the second comparator outputs a low level, meaning the auxiliary heating control signal is 0. The second power switch MOS2 is turned off, and the second power resistor *N stops heating. Responding to the low level output of the second comparator, the second buck converter chip DC-DC2 remains on, and the heating circuit continues to operate.

[0085] When the temperature of the circuit to be heated is less than or equal to 5°C and greater than 0°C, in a specific embodiment, the initial temperature of the circuit to be heated and the thermistor are in the range of 5°C decreasing to 0°C. When the temperature decreases from 5°C to 0°C, the temperature decreases and the resistance of the first thermistor RT1 increases. At this time, the voltage division of RT1 and R4 is still less than the reference voltage of the first comparator, i.e., the reference voltage 1. At this time, the first comparator outputs a low level, that is, the main heating control signal is 0, the first power switch MOS1 is turned off, and the first power resistor *M stops heating.

[0086] When the temperature drops from 5℃ to 0℃, the resistance of the second thermistor RT2 increases. The voltage division between RT2 and R8 is still less than the reference voltage (reference voltage 2) of the second comparator. At this time, the second comparator outputs a low level, meaning the auxiliary heating control signal is 0. The second power switch MOS2 is turned off, and the second power resistor *N stops heating. Responding to the low level output of the second comparator, the second buck converter chip DCDC2 remains on, and the heating circuit continues to operate.

[0087] In one specific embodiment, when the circuit to be heated is at -5℃, the initial temperature of the circuit to be heated and the thermistor is -5℃. When the temperature drops to -5℃, the resistance of the first thermistor RT1 increases. At this time, the voltage division of RT1 and R4 is greater than the reference voltage of the first comparator, i.e., reference voltage 1. At this time, the first comparator outputs a high level, that is, the main heating control signal is 1. The first power switch MOS1 is connected, and the first power resistor *M starts heating to heat the circuit to be heated.

[0088] When the temperature drops to -5℃, the resistance of the second thermistor RT2 increases. The voltage division between RT2 and R8 is still less than the reference voltage (reference voltage 2) of the second comparator. At this time, the second comparator outputs a low level, meaning the auxiliary heating control signal is 0. The second power switch MOS2 is turned off, and the second power resistor *N stops heating. Responding to the low level output of the second comparator, the second buck converter chip DCDC2 remains on, and the heating circuit continues to operate.

[0089] When the temperature of the circuit to be heated is greater than or equal to 5°C, in a specific embodiment, the initial temperature of the circuit to be heated and the thermistor is 5°C. When the temperature rises to greater than or equal to 5°C, the resistance of the first thermistor RT1 decreases. At this time, the voltage division of RT1 and R4 is less than the reference voltage of the first comparator, i.e., the reference voltage 1. At this time, the first comparator outputs a low level, that is, the main heating control signal is 0, the first power switch MOS1 is turned off, and the first power resistor *M stops heating.

[0090] When the temperature rises to 5°C or higher, the resistance of the second thermistor RT2 decreases. The voltage drop across RT2 and R8 is less than the reference voltage (reference voltage 2) of the second comparator. At this point, the second comparator outputs a low level, meaning the auxiliary heating control signal is 0. The second power switch MOS2 is turned off, and the second power resistor *N stops heating. Responding to the low level output of the second comparator, the second buck converter chip DC-DC2 remains on, and the heating circuit continues to operate.

[0091] In one possible implementation, as the main heating is turned on, the temperature rises. When the temperature of the circuit to be heated is greater than or equal to 5°C, in a specific embodiment, the initial temperature of the circuit to be heated and the thermistor is 5°C. The resistance of the first thermistor RT1 decreases. At this time, the voltage division of RT1 and R4 is less than the reference voltage of the first comparator, i.e., the reference voltage 1. At this time, the first comparator outputs a low level, that is, the main heating control signal is 0. The first power switch MOS1 is turned off, and the first power resistor *M stops heating.

[0092] At this point, the resistance of the second thermistor RT2 decreases. The voltage drop across RT2 and R8 is now less than the reference voltage (reference voltage 2) of the second comparator. The second comparator outputs a low level, meaning the auxiliary heating control signal is 0. The second power switch MOS2 is turned off, and the second power resistor *N stops heating. Responding to the low level output of the second comparator, the second buck converter chip DCDC2 remains on, and the heating circuit continues to operate.

[0093] When the temperature of the circuit to be heated is less than or equal to -5℃, in a specific embodiment, when the initial temperature of the circuit to be heated and the thermistor is -5℃, the resistance of the first thermistor RT1 increases. At this time, the voltage division of RT1 and R4 is greater than the reference voltage of the first comparator, i.e., the reference voltage 1. At this time, the first comparator outputs a high level, that is, the main heating control signal is 1, the first power switch MOS1 is connected, and the first power resistor *M starts heating to heat the circuit to be heated, that is, the main heating module starts to heat the circuit to be heated.

[0094] At this point, the resistance of the second thermistor RT2 increases. The voltage division between RT2 and R8 is still less than the reference voltage (reference voltage 2) of the second comparator. Therefore, the second comparator outputs a low level, meaning the auxiliary heating control signal is 0. The second power switch MOS2 is turned off, and the second power resistor *N stops heating. Responding to the low level output of the second comparator, the second buck converter chip DCDC2 remains on, and the circuit to be heated continues to operate, returning to the previous step. This cycle repeats, maintaining the temperature of the circuit to be heated within the range of -5℃ to 5℃.

[0095] Specific references Figure 2 As a specific embodiment of the working method of the low-temperature heating circuit system of this application, Figure 2 A flowchart illustrating the operation of a low-temperature heating circuit system device according to an embodiment of this application is provided.

[0096] In step 201, when the ambient temperature is -40℃, the temperature of the circuit to be heated is also -40℃. The first power switch MOS1 and the second power switch MOS2 are turned on to heat the circuit to be heated, and the circuit to be heated is not powered on.

[0097] In step 202, when the temperature of the circuit to be heated rises from -40℃ to above 0℃, the first power switch MOS1 turns on and the second power switch MOS2 turns off, the circuit to be heated is powered on and starts working.

[0098] In step 203, when the temperature of the circuit to be heated continues to rise from 0°C to above 5°C, the first power switch MOS1 is turned off, the second power switch MOS2 is turned off, and the circuit to be heated continues to work.

[0099] In step 204, when the temperature of the circuit to be heated drops from 5°C to 0°C, the first power switch MOS1 is turned off and the second power switch MOS2 is turned off, and the circuit to be heated continues to work.

[0100] In step 205, when the temperature of the circuit to be heated drops from 0°C to below -5°C, the first power switch MOS1 turns on and the second power switch MOS2 turns off, and the circuit to be heated continues to work.

[0101] In step 206, when the temperature of the circuit to be heated rises from -5℃ to above 5℃, the first power switch MOS1 is turned off, the second power switch MOS2 is turned off, and the circuit to be heated continues to work.

[0102] In step 207, this cycle repeats, with the first power switch MOS1 turning off and on as the temperature of the circuit to be heated changes between 5°C and -5°C, while the second power switch MOS2 remains off, ensuring that the temperature of the circuit to be heated is controlled between -5°C and 5°C.

[0103] In step 208, when the ambient temperature returns to above 5°C and the temperature of the circuit to be heated is also above 5°C, both the first power switch MOS1 and the second power switch MOS2 are turned off, and the first power switch MOS1 is no longer turned on; the first power switch MOS1 will only be turned on when the ambient temperature and the temperature of the circuit to be heated continue to be below -5°C.

[0104] Specific references Figure 3 and Figure 4 As a specific embodiment of the working method of the low-temperature heating circuit system of this application, Figure 3 This document shows a flowchart illustrating a voltage division method for a low-temperature heating circuit system according to an embodiment of this application. Figure 4 The diagram shows the characteristic relationship between the input voltage divider and the output of reference voltage 1 and reference voltage 2 in an embodiment of this application.

[0105] In step 301, the circuit to be heated is frozen thoroughly in a low-temperature environment of -40°C. The resistance values of the first thermistor RT1 and the second thermistor RT2 are very large, and the voltage division is very large. For example, the voltage division is 2V. It is higher than REF1-VL (reverse threshold reference voltage 1) and REF2-VL (reverse threshold reference voltage 2) of the first comparator and the second comparator. The Heat_Ctl (main heating control) signal is 1, and the Pwr_Ctl (auxiliary heating control) signal is 1. The main heating and the auxiliary heating work simultaneously;

[0106] In step 302, after heating for a period of time, the temperature of the circuit to be heated ranges from -40°C to -5°C. The first thermistor RT1 and the second thermistor RT2 decrease, and the voltage division decreases. For example, the voltage division is 0.72V. It is still higher than REF1-VL (reverse threshold reference voltage 1) and REF2-VL (reverse threshold reference voltage 2) of the first comparator and the second comparator. The Heat_Ctl (main heating control) signal is 1, and the Pwr_Ctl (auxiliary heating control) signal is 1. The main heating and the auxiliary heating continue to work;

[0107] In step 303, when the temperature of the circuit to be heated ranges from -5°C to 0°C, the first thermistor RT1 and the second thermistor RT2 continue to decrease, and the voltage division continues to decrease. For example, the voltage division is 0.58. REF2-VL (reverse threshold reference voltage 2)>voltage division>REF1-VL (reverse threshold reference voltage 1). The Heat_Ctl (main heating control) signal is 1, and the Pwr_Ctl (auxiliary heating control) signal is 0. The main heating continues, the auxiliary heating is turned off, and at the same time, the second step-down chip DCDC2 is turned on, and the system starts to work and generates heat;

[0108] In step 304, when the temperature of the circuit to be heated ranges from 0°C to 5°C, the first thermistor RT1 and the second thermistor RT2 continue to decrease, and the voltage division continues to decrease. For example, the voltage division is 0.48. REF2-VL (reverse threshold reference voltage 2)>REF1-VL (reverse threshold reference voltage 1)>voltage division. The Heat_Ctl (main heating control) signal is 0, and the Pwr_Ctl (auxiliary heating control) signal is 0. The main heating is turned off, and the auxiliary heating is turned off. The system continues to work;

[0109] In step 305, since the heat generated by the system operation is relatively small, after the main and auxiliary heating are both turned off, the temperature of the circuit to be heated drops rapidly with the ambient temperature. When the temperature ranges from 5°C to 0°C, the voltage division increases to 0.58V < REF1-VH (forward threshold reference voltage 1) < REF2-VH (forward threshold reference voltage 2). The Heat_Ctl (main heating control) signal is 0, and the Pwr_Ctl (auxiliary heating control) signal is 0. The main heating is turned off, and the auxiliary heating is turned off. The system continues to work;

[0110] In step 306, the temperature of the circuit to be heated continues to decrease. When it drops to -5℃, the voltage divider reaches its maximum value at REF2-VH (positive threshold reference voltage 2) > 0.72 > REF1-VH (positive threshold reference voltage 1). The Heat_Ctl (main heating control) signal is 1, and the Pwr_Ctl (auxiliary heating control) signal is 0. The main heating is turned on, the auxiliary heating is turned off, and the system continues to work.

[0111] In step 307, as the main heater is turned on, the temperature rises. When it reaches 5°C, the Heat_Ctl (main heater control) signal is 0, the Pwr_Ctl (auxiliary heater control) signal is 0, the main heater is turned off, the auxiliary heater is turned off, and the system continues to work.

[0112] In step 308, return to step 306 and repeat this cycle to ensure that the Pwr_Ctl (auxiliary heating control) signal is 0, the system is always in working state, and the working temperature is between -5℃ and 5℃.

[0113] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A heating control method for a low-temperature heating circuit, characterized in that: Heating control is achieved using a low-temperature heating circuit system; The low-temperature heating circuit system includes a main heating module, an auxiliary heating module, a first step-down chip, and a second step-down chip. The main heating module includes a first thermistor, a first comparator, a first power switch, and a first power resistor. The output terminal of the first comparator is connected to the control terminal of the first power switch. One end of the first power switch is connected to the power supply, and the other end is connected to the first power resistor. The first power resistor is used to heat the circuit to be heated. The auxiliary heating module includes a second thermistor, a second comparator, a second power switch, and a second power resistor; The output of the second comparator is connected to the control terminal of the second power switch. One end of the second power switch is connected to the power supply, and the other end is connected to the second power resistor. The second power resistor is used to heat the circuit to be heated. The first step-down chip provides power to the low-temperature heating circuit system, and the second step-down chip, controlled by the second comparator, provides power to the circuit to be heated. The method includes: When the temperature of the circuit to be heated is -40℃, the first power switch and the second power switch are turned on simultaneously, and heating is provided to the circuit to be heated through the first power resistor and the second power resistor. When the temperature of the circuit to be heated rises above 0°C, the first power switch remains on and the second power switch is off, and the circuit to be heated is powered on and begins to work. When the temperature of the circuit to be heated rises to above 5°C, both the first power switch and the second power switch are turned off, and the circuit to be heated maintains normal operation. When the temperature of the circuit to be heated drops from 5°C to below -5°C, the first power switch is turned on and the second power switch remains closed, and the circuit to be heated continues to work in the heating state. When the temperature of the circuit to be heated rises from -5℃ to above 5℃, the first power switch and the second power switch are turned off again, and the circuit continues to operate. Thereafter, the first power switch cycles on and off between 5℃ and -5℃ depending on the temperature of the circuit to be heated, while the second power switch remains off, so that the operating temperature of the circuit to be heated is maintained between -5℃ and 5℃.

2. The method according to claim 1, characterized in that, When the ambient temperature rises above 5°C and the temperature of the circuit to be heated simultaneously reaches above 5°C, both the first power switch and the second power switch are turned off, and the first power switch will not turn on automatically until the ambient temperature and the temperature of the circuit to be heated fall below -5°C again, at which point the first power switch will turn on again.

3. The method according to claim 2, characterized in that, The first comparator compares the voltage of the first thermistor at the non-inverting input with the first reference voltage at the inverting input. When the voltage of the first thermistor at the non-inverting input is greater than the first reference voltage at the inverting input, it outputs a high level; when the voltage of the first thermistor at the non-inverting input is less than the first reference voltage at the inverting input, it outputs a low level. The second comparator compares the voltage of the second thermistor at the non-inverting input with the second reference voltage at the inverting input. When the voltage of the second thermistor at the non-inverting input is greater than the second reference voltage at the inverting input, it outputs a high level; when the voltage of the second thermistor at the non-inverting input is less than the second reference voltage at the inverting input, it outputs a low level.

4. The heating control method for a low-temperature heating circuit according to claim 3, characterized in that, The connection and disconnection of the first power switch depend on the signal output by the first comparator, and the connection and disconnection of the second power switch depend on the signal output by the second comparator.

5. The method according to claim 4, characterized in that, include: When the temperature of the circuit to be heated rises from -40℃ to -5℃, the first comparator obtains a voltage drop greater than its reference voltage through the first thermistor, and the first comparator outputs a high level. After being inverted by the first transistor, the first power switch is turned on. The second comparator obtains a voltage drop greater than its reference voltage through the second thermistor, and the second comparator outputs a high level. After being inverted by the second transistor, the second power switch is turned on. When the temperature of the circuit to be heated rises from -5℃ to 0℃, the first comparator obtains a voltage drop through the first thermistor, but it is still greater than its reference voltage. The first comparator outputs a high level, which is inverted by the first transistor, and the first power switch is turned on. The second comparator obtains a voltage drop through the second thermistor, which is less than its reference voltage. The second comparator outputs a low level, which is inverted by the second transistor, and the second power switch is turned off, and the circuit to be heated begins to work. When the temperature of the circuit to be heated rises from 0°C to 5°C, the first comparator obtains a voltage drop through the first thermistor that is less than its reference voltage. The first comparator outputs a low level, which is then inverted by the first transistor, and the first power switch is turned off. The second comparator obtains a voltage drop through the second thermistor that is less than its reference voltage. The second comparator outputs a low level, which is then inverted by the second transistor, and the second power switch is turned off. The circuit to be heated continues to operate.

6. The method according to claim 5, characterized in that, The method further includes: When the temperature of the circuit to be heated drops from 5°C to 0°C, the first comparator obtains a voltage drop through the first thermistor that is less than its reference voltage. The first comparator outputs a low level, which is then inverted by the first transistor, and the first power switch is turned off. The second comparator obtains a voltage drop through the second thermistor that is less than its reference voltage. The second comparator outputs a low level, which is then inverted by the second transistor, and the second power switch is turned off. The circuit to be heated continues to operate. When the temperature of the circuit to be heated drops to -5℃, the first comparator obtains a voltage drop greater than its reference voltage through the first thermistor, and the first comparator outputs a high level. After being inverted by the first transistor, the first power switch is turned on. The second comparator obtains a voltage drop less than its reference voltage through the second thermistor, and the second comparator outputs a high level. After being inverted by the second transistor, the second power switch is turned off, and the circuit to be heated continues to operate. When the temperature of the circuit to be heated rises to 5°C, the first comparator obtains a voltage drop through the first thermistor that is less than its reference voltage. The first comparator outputs a low level, which is then inverted by the first transistor, and the first power switch is turned off. The second comparator obtains a voltage drop through the second thermistor that is less than its reference voltage. The second comparator outputs a low level, which is then inverted by the second transistor, and the second power switch is turned off. The circuit to be heated continues to operate.

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