PTC heater control system based on pwm control and automobile

Abstract

The present disclosure provides a PWM control-based PTC heater control system and a car, and belongs to the technical field of PTC heating, wherein the PTC heater control system comprises: a PWM control signal receiving end capable of receiving a PWM control signal input from outside the system; a PTC driving circuit capable of outputting a corresponding PTC driving signal according to the received PWM control signal; a hysteresis comparator circuit arranged between the PWM control signal receiving end and the PTC driving circuit, wherein the inverting input end of the hysteresis comparator circuit is connected with the PWM control signal receiving end, and the output end of the hysteresis comparator circuit is connected with the PTC driving circuit. The technical scheme of the present disclosure can effectively reduce the size of the PTC heater control system and reduce the cost.

Description

Technical Field

[0001] This disclosure relates to the field of PTC heating technology, and in particular to a PTC heater control system based on PWM control and an automobile. Background Technology

[0002] Traditional high-voltage PTC heaters typically use relays as passive switching devices. By switching the input signal between floating and pulled-down states, they control the conduction and cutoff of the high-voltage circuit, thereby controlling the PTC heater's power level and achieving different power settings. However, relays as control devices have several disadvantages, such as difficulty in implementing complex controls, large relay size leading to an excessively large PTC heating circuit, significant noise during switching operations, and short service life.

[0003] Related technologies have proposed a PTC heater control system based on PWM-controlled semiconductor devices for switching control, which can effectively improve the aforementioned technical problems. However, in actual production, it has been found that the PWM-controlled PTC heater control system proposed in this technology has high cost and a relatively large overall system size. Utility Model Content

[0004] This disclosure aims to at least solve one of the technical problems existing in the prior art, and proposes a PTC heater control system and automobile based on PWM control.

[0005] In a first aspect, this disclosure provides a PTC heater control system based on PWM control, comprising:

[0006] A PWM control signal receiver capable of receiving PWM control signals input from outside the system;

[0007] A PTC drive circuit capable of outputting a corresponding PTC drive signal based on the received PWM control signal;

[0008] A hysteresis comparator circuit is disposed between the PWM control signal receiving terminal and the PTC drive circuit. The inverting input terminal of the hysteresis comparator circuit is connected to the PWM control signal receiving terminal, and the output terminal of the hysteresis comparator circuit is connected to the PTC drive circuit.

[0009] In some implementations, the PTC heater control system based on PWM control also includes:

[0010] The inverter circuit is configured such that the output of the hysteresis comparator circuit is connected to the PTC drive circuit, the input of the inverter circuit is connected to the output of the comparator circuit, and the output of the inverter circuit is connected to the PTC drive circuit.

[0011] In some embodiments, the hysteresis comparator circuit includes: an operational amplifier, a reference voltage supply circuit, a negative feedback circuit, an input noise reduction circuit, an input protection circuit, and an output noise reduction circuit;

[0012] The reference voltage supply circuit is connected to the non-inverting input of the operational amplifier;

[0013] The negative feedback circuit is connected to the output terminal and the inverting input terminal of the operational amplifier;

[0014] The input noise reduction circuit and the input protection circuit are connected in series between the input terminal of the hysteresis comparator circuit and the inverting input terminal of the negative feedback circuit.

[0015] The output terminal of the operational amplifier is connected to the output terminal of the hysteresis comparator circuit through the output noise reduction circuit.

[0016] In some embodiments, the reference voltage supply circuit includes: a first resistor, a second resistor, and a third resistor, wherein a first end of the first resistor is connected to a preset operating voltage terminal, a second end of the first resistor is connected to the first end of the second resistor and the first end of the third resistor, a second end of the second resistor is grounded, and a second end of the third resistor is connected to the non-inverting input terminal of the operational amplifier.

[0017] And / or,

[0018] The negative feedback circuit includes a fourth resistor and a fifth resistor. The first end of the fourth resistor is connected to the inverting input terminal of the operational amplifier, the second end of the fourth resistor is connected to the first end of the fifth resistor, and the second end of the fifth resistor is connected to the output terminal of the operational amplifier.

[0019] And / or,

[0020] The input noise reduction circuit includes a sixth resistor, a seventh resistor, and a first capacitor. The first end of the sixth resistor is connected to the input terminal of the hysteresis comparator circuit, and the second end of the sixth resistor is grounded. The first end of the seventh resistor is connected to the input terminal of the hysteresis comparator circuit, and the second end of the seventh resistor is connected to the input protection circuit. The first end of the first capacitor is connected to the input terminal of the hysteresis comparator circuit, and the second end of the first capacitor is grounded.

[0021] And / or,

[0022] The input protection circuit includes a first diode, a second diode, and a third diode. The cathode of the first diode is connected to the input noise reduction circuit, and the anode of the first diode is grounded. The cathode of the second diode is connected to a preset protection voltage supply terminal, and the anode of the second diode is connected to the non-inverting input terminal of the operational amplifier and the input noise reduction circuit. The cathode of the third diode is connected to the protection voltage supply terminal, and the anode of the third diode is grounded.

[0023] And / or,

[0024] The output noise reduction circuit includes an eighth resistor, a ninth resistor, and a second capacitor. The first end of the eighth resistor is connected to the output terminal of the operational amplifier, and the second end of the eighth resistor is grounded. The first end of the ninth resistor is connected to the output terminal of the operational amplifier, and the second end of the ninth resistor is connected to the output terminal of the hysteresis comparator circuit. The first end of the second capacitor is connected to the output terminal of the hysteresis comparator circuit, and the second end of the second capacitor is grounded.

[0025] In some embodiments, it further includes: a first power module, a low-dropout linear regulator, and an isolated boost circuit;

[0026] The first power module is connected to the low dropout linear regulator and the isolation boost circuit respectively, and is able to provide a first operating voltage to the low dropout linear regulator and the isolation boost circuit respectively;

[0027] The low-dropout linear regulator is connected to the PTC drive circuit and can generate a second operating voltage based on the first operating voltage, and provide the second operating voltage to the PTC drive circuit. The second operating voltage is less than the first operating voltage.

[0028] The isolation boost circuit is connected to the PTC drive circuit and can generate a third working voltage based on the second working voltage, and provide the third working voltage to the PTC drive circuit. The third working voltage is greater than the first working voltage.

[0029] In some embodiments, the first power module includes: a first power supply and a power filter;

[0030] The power filter is connected to the first power supply, the low-dropout linear regulator, and the isolation boost circuit, and can filter the voltage signal output by the first power supply and output the first operating voltage.

[0031] In some embodiments, the PTC heater control system based on PWM control further includes: a second power supply and at least one PTC heating circuit, wherein the PTC heating circuit is disposed between the second power supply and a ground terminal;

[0032] The second power source can provide a fourth operating voltage to the PTC heating circuit;

[0033] The PTC heating circuit includes a PTC heating load and a switching transistor connected in series. The switching transistor is connected to the output terminal of the PTC driving circuit and can control the on / off state of the PTC heating circuit according to the PTC driving signal output by the PTC driving circuit.

[0034] In some embodiments, the switching transistor includes an insulated gate bipolar transistor.

[0035] In some embodiments, the PTC drive circuit is an isolated driver.

[0036] In a second aspect, embodiments of this disclosure provide an automobile, including: the PTC heating control system as provided in the first aspect.

[0037] The technical solution disclosed herein has at least the following beneficial technical effects:

[0038] Unlike related technologies that use MCU chips or PWM generator chips within the PTC heater control system to generate PWM control signals, this disclosure uses PWM control signals directly from an external system (e.g., an vehicle control system), eliminating the need for MCU chips or PWM generator chips. However, considering the short effective transmission distance of PWM signals, the PWM control signal is prone to noise and distortion during transmission from the external system to the PTC drive circuit, potentially leading to incorrect PTC drive signals output by the PTC drive circuit. Therefore, this disclosure adds a hysteresis comparator circuit to the signal transmission path between the PWM control signal receiver and the PTC drive circuit. This hysteresis comparator circuit effectively reduces jitter and noise during high-low level transitions in the PWM control signal, improving signal quality and transmission reliability. Furthermore, the size and cost of the hysteresis comparator circuit in this disclosure are significantly smaller than those of MCU chips and PWM generator chips, thus effectively reducing the overall system size and cost. Attached Figure Description

[0039] Figure 1 This is a structural block diagram of a PTC heater control system based on PWM control, provided in related technologies.

[0040] Figure 2 A structural block diagram of a PTC heater control system based on PWM control provided in this disclosure embodiment;

[0041] Figure 3 This is a schematic diagram of a circuit structure for a hysteresis comparator circuit in an embodiment of this disclosure;

[0042] Figure 4 This is a structural block diagram of another PTC heater control system based on PWM control provided in an embodiment of this disclosure. Detailed Implementation

[0043] To enable those skilled in the art to better understand the technical solutions of this disclosure, the disclosure will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an,” “a,” or “the,” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising,” “including,” or “including,” and similar terms mean that the element or object preceding the term encompasses the elements or objects listed following the term and their equivalents, without excluding other elements or objects. The terms “connected,” “linked,” or “connected,” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect.

[0045] In the various figures, the same elements are represented by similar reference numerals. For clarity, not all parts in the figures are drawn to scale. Furthermore, certain well-known parts may not be shown in the figures. Many specific details of this disclosure, such as specific circuit structures, are described below to provide a clearer understanding of the disclosure. However, as those skilled in the art will understand, this disclosure may be implemented without adhering to these specific details.

[0046] Figure 1 This is a structural block diagram of a PTC heater control system based on PWM control, provided in related technologies. (Example:) Figure 1 As shown, the PTC heater control system based on PWM control provided by the related technology includes: a control signal receiving terminal IN_CT, an MCU chip (or a PWM generator chip), a PTC drive circuit 1, and a PTC heating circuit 2. The control signal receiving terminal IN_CT is connected to an external system (such as an vehicle control system), and the PTC heating circuit 2 includes a switching transistor SW and a PTC heating load.

[0047] The temperature control process is as follows: An external system sends a control signal to the MCU chip (or PWM generator chip). The MCU chip (or PWM generator chip) outputs a corresponding PWM control signal based on the received control signal. Then, the PTC drive circuit 1 outputs a corresponding PTC drive signal (essentially a PWM signal) based on the PWM control signal. The switching transistor SW turns on or off based on the received PTC drive signal, thereby controlling the on / off state of the PTC heating circuit 2, and thus adjusting the power of the PTC heating circuit 2. By using different PWM control signal duty cycles, the PTC heating circuit can be adjusted across its entire power range from 0% to 100%.

[0048] In related technologies, the cost of the entire PTC heater control system is high because MCU chips and PWM generator chips are relatively expensive; at the same time, the large size of MCU chips and PWM generator chips results in a large size of the entire PTC heater control system.

[0049] To effectively improve the aforementioned technical problems in related technologies, this disclosure provides a new PTC heater control system based on PWM control, which will be described in detail below with reference to specific accompanying drawings.

[0050] Figure 2 This is a structural block diagram of a PTC heater control system based on PWM control, provided as an embodiment of the present disclosure. Figure 2 As shown, the PTC heater control system based on PWM control includes: a PWM control signal receiving terminal IN_PWM, a PTC drive circuit 1, and a hysteresis comparator circuit 3. The PWM control signal receiving terminal IN_PWM receives PWM control signals input from outside the system; the PTC drive circuit 1 outputs a corresponding PTC drive signal based on the received PWM control signal; the hysteresis comparator circuit 3 is located between the PWM control signal receiving terminal IN_PWM and the PTC drive circuit 1, with its inverting input connected to the PWM control signal receiving terminal IN_PWM and its output connected to the PTC drive circuit 1.

[0051] In some embodiments, the PTC drive circuit 1 is an isolation driver. An isolation driver refers to a drive circuit 1 with electrical isolation function, which can achieve electrical isolation between the input side and the output side of the drive circuit 1 while performing the drive function.

[0052] Unlike related technologies that use an MCU chip or PWM generator chip within the PTC heater control system to generate PWM control signals, in this disclosure, the PWM control signal originates directly from an external system (e.g., an onboard control system), thus eliminating the need for an MCU chip or PWM generator chip. However, considering the short effective transmission distance of the PWM signal, there is a risk of high noise and distortion during transmission from the external system to the PTC drive circuit 1, potentially leading to incorrect PTC drive signals output by the PTC drive circuit 1. Therefore, this disclosure adds a hysteresis comparator circuit 3 to the signal transmission path between the PWM control signal receiver IN_PWM and the PTC drive circuit 1. The hysteresis comparator circuit 3 effectively reduces jitter and noise during high-low level transitions in the PWM control signal, improving the quality of the PWM control signal and enhancing reliability during transmission.

[0053] Furthermore, the size of the hysteresis comparator circuit 3 in this disclosure is much smaller than that of the MCU chip and the PWM generator chip, and its cost is also much lower than that of the MCU chip and the PWM generator chip. Therefore, the technical solution of this disclosure can effectively reduce the size of the entire system and reduce the cost of the entire system.

[0054] In this disclosure, the hysteresis comparator circuit 3 is constructed using an operational amplifier with negative feedback. The input and output terminals are connected by a resistor to form negative feedback, effectively establishing a threshold hold function. When the voltage at the inverting input terminal of the hysteresis comparator circuit 3 is higher than a preset upper threshold voltage, the output terminal of the hysteresis comparator circuit 3 outputs a low-level voltage; when the voltage at the inverting input terminal of the hysteresis comparator circuit 3 is lower than a preset lower threshold voltage, the output terminal of the hysteresis comparator circuit 3 outputs a high-level voltage. This is effective. By adding the hysteresis comparator circuit 3 to the signal transmission path between the PWM control signal receiver IN_PWM and the PTC drive circuit 1, the system's resistance to jitter and noise during the high-low level transitions of the PWM control signal is enhanced.

[0055] Figure 3 This is a schematic diagram of a hysteresis comparator circuit in one embodiment of this disclosure. Figure 3As shown, the hysteresis comparator circuit 3 includes: an operational amplifier OP1, a reference voltage supply circuit 301, a negative feedback circuit 302, an input noise reduction circuit 303, an input protection circuit 304, and an output noise reduction circuit 305. The reference voltage supply circuit 301 is connected to the non-inverting input terminal of the operational amplifier OP1, the negative feedback circuit 302 is connected to the output terminal and the inverting input terminal of the operational amplifier OP1, the input noise reduction circuit 303 and the input protection circuit 304 are connected in series between the input terminal IN of the hysteresis comparator circuit 3 and the inverting input terminal of the negative feedback circuit 302, and the output terminal of the operational amplifier OP1 is connected to the output terminal OUT of the hysteresis comparator circuit 3 through the output noise reduction circuit 305.

[0056] The reference voltage supply circuit 301 provides a reference voltage Vref to the non-inverting input of the operational amplifier OP1. The input noise reduction circuit 303 performs noise reduction processing on the PWM control signal input to the input terminal IN of the hysteresis comparator circuit 3. The input protection circuit 304 protects the input terminal IN of the hysteresis comparator circuit 3. The output noise reduction circuit 305 performs noise reduction processing on the PWM control signal output to the output terminal OUT of the hysteresis comparator circuit 3.

[0057] In some embodiments, the reference voltage supply circuit 301 includes a first resistor R1, a second resistor R2, and a third resistor R3. The first terminal of the first resistor R1 is connected to a preset operating voltage terminal. The second terminal of the first resistor R1 is connected to the first terminals of the second resistor R2 and the third resistor R3. The second terminal of the second resistor R2 is grounded. The second terminal of the third resistor R3 is connected to the non-inverting input terminal of the operational amplifier OP1. By designing the first resistor R1 and the second resistor R2, the voltage VCC is divided to obtain the reference voltage Vref.

[0058] In some embodiments, the negative feedback circuit 302 includes a fourth resistor R4 and a fifth resistor R5. The first end of the fourth resistor R4 is connected to the inverting input of the operational amplifier OP1, the second end of the fourth resistor R4 is connected to the first end of the fifth resistor R5, and the second end of the fifth resistor R5 is connected to the output of the operational amplifier OP1.

[0059] In some embodiments, the input noise reduction circuit 303 includes: a sixth resistor R6, a seventh resistor R7, and a first capacitor C1. The first end of the sixth resistor R6 is connected to the input terminal IN of the hysteresis comparator circuit 3, and the second end of the sixth resistor R6 is grounded. The first end of the seventh resistor R7 is connected to the input terminal IN of the hysteresis comparator circuit 3, and the second end of the seventh resistor R7 is connected to the input protection circuit 304. The first end of the first capacitor C1 is connected to the input terminal IN of the hysteresis comparator circuit 3, and the second end of the first capacitor C1 is grounded.

[0060] In some embodiments, the input protection circuit 304 includes: a first diode D1, a second diode D2, and a third diode D3. The cathode of the first diode D1 is connected to the input noise reduction circuit 303, and the anode of the first diode D1 is grounded. The cathode of the second diode D2 is connected to a preset protection voltage supply terminal (providing protection voltage Vp), and the anode of the second diode D2 is connected to the non-inverting input terminal of the operational amplifier OP1 and the input noise reduction circuit 303. The cathode of the third diode D3 is connected to the protection voltage supply terminal, and the anode of the third diode D3 is grounded.

[0061] The three diodes described above effectively prevent voltage fluctuations or instantaneous voltage from damaging the IN_PWM port of the PWM control signal receiver, thus protecting the port. Optionally, the first diode D1 is a Zener diode, and the second diode D2 and the third diode D3 are ESD diodes.

[0062] In some embodiments, the output noise reduction circuit 305 includes: an eighth resistor R8, a ninth resistor R9, and a second capacitor C2. The first end of the eighth resistor R8 is connected to the output terminal of the operational amplifier OP1, and the second end of the eighth resistor R8 is grounded. The first end of the ninth resistor R9 is connected to the output terminal of the operational amplifier OP1, and the second end of the ninth resistor R9 is connected to the output terminal OUT of the hysteresis comparator circuit 3. The first end of the second capacitor C2 is connected to the output terminal OUT of the hysteresis comparator circuit 3, and the second end of the second capacitor C2 is grounded.

[0063] In some embodiments, a third capacitor C3 may be added to the hysteresis comparator circuit 3 to improve voltage stability.

[0064] It should be noted that, as Figure 3 The illustration only shows, by way of example, the input noise reduction circuit 303 located between the input protection circuit 304 and the input terminal IN of the hysteresis comparator circuit 3, that is, the PWM control signal passes through the input noise reduction circuit 303 first and then through the input protection circuit 304. In this disclosure, the input protection circuit 304 may also be located between the input noise reduction circuit 303 and the input terminal IN of the hysteresis comparator circuit 3, that is, the PWM control signal passes through the input protection circuit 304 first and then through the input noise reduction circuit 303.

[0065] In some embodiments, the PTC heater control system based on PWM control further includes: a first power supply module 4, a low-dropout linear regulator 5, and an isolation boost circuit 6.

[0066] The first power module 4 is connected to the low dropout linear regulator 5 and the isolation boost circuit 6 respectively, and the first power module 4 can provide the first operating voltage to the low dropout linear regulator 5 and the isolation boost circuit 6 respectively.

[0067] The low-dropout linear regulator 5 is connected to the PTC drive circuit 1. The low-dropout linear regulator 5 can generate a second working voltage based on the first working voltage and provide the second working voltage to the PTC drive circuit 1. The second working voltage is less than the first working voltage.

[0068] The isolation boost circuit 6 is connected to the PTC drive circuit 1. The isolation boost circuit 6 can generate a third working voltage based on the second working voltage and provide the third working voltage to the PTC drive circuit 1. The third working voltage is greater than the first working voltage.

[0069] It should be noted that the isolated boost circuit 6 disclosed herein is a boost circuit with electrical isolation function, that is, it achieves electrical isolation between the different high and low voltages at its two ends. As an example, the isolated boost circuit 6 is a DC-DC boost circuit.

[0070] The second operating voltage is the low-voltage operating voltage required by the PTC driver circuit 1, and the third operating voltage is the high-voltage operating voltage required by the PTC driver circuit 1. As an example, the first operating voltage is 12V, the second operating voltage is 5V, and the third operating voltage is 15V.

[0071] In some embodiments, the first power module 4 includes: a first power supply and a power filter (Electromagnetic Interference filter, abbreviated as EMI); wherein the first power supply serves as the low-voltage power supply in the entire system; the power filter is connected to the first power supply, the low-dropout linear regulator 5 and the isolation boost circuit 6, and is capable of filtering the voltage signal output by the first power supply and outputting a first operating voltage.

[0072] In some embodiments, the PWM-based PTC heater control system further includes a second power supply 7 and at least one PTC heating circuit 2, wherein the PTC heating circuit 2 is disposed between the second power supply 7 and the ground terminal.

[0073] It should be noted that the attached figure only shows one PTC heating circuit 2 as an example. In actual applications, two or even more PTC heating circuits 2 can be set. This disclosure does not limit this.

[0074] The second power supply 7 serves as the high-voltage power supply for the entire system, and it can provide a fourth operating voltage to the PTC heating circuit. In some embodiments, the fourth operating voltage is 48V.

[0075] The PTC heating circuit 2 includes a PTC heating load connected in series and a switching transistor SW. The switching transistor SW is connected to the output terminal of the PTC drive circuit 1 and can control the on / off state of the PTC heating circuit 2 according to the PTC drive signal output by the PTC drive circuit 1. When the switching transistor SW is in the on state, the PTC heating circuit 2 is in the on state, and the PTC heating load is heated; when the switching transistor SW is in the off state, the PTC heating circuit 2 is in the off state, and the PTC heating load stops heating.

[0076] Optionally, the switching transistor SW can be an insulated-gate bipolar transistor (IGBT). This is because IGBTs have the ability to withstand higher voltages and larger currents, as well as good thermal stability (they can operate normally at higher temperatures), making them extremely suitable for PTC heating circuits 2. Of course, in this disclosure, the switching transistor SW can also be other transistors, such as MOS transistors.

[0077] Figure 4 This is a structural block diagram of another PTC heater control system based on PWM control provided in an embodiment of this disclosure. Figure 4 As shown, compared to the previous embodiment, an inverting circuit 8 is added between the output of the hysteresis comparator circuit 3 and the PTC drive circuit 1 in this embodiment. Only this part will be described in detail below.

[0078] As described above, after the hysteresis comparator circuit 3 is used to dejitter and reduce noise in the PWM control signal, the PWM control signal will be inverted. Although the inversion of the PWM control signal does not affect the driving of the PTC drive circuit 1, it can easily cause the switching transistor SW to mis-turn on when the system is powered on. To address this, an inverting circuit is added between the output of the hysteresis comparator circuit 3 and the PTC drive circuit 1. This inverting circuit further inverts the PWM control signal output by the hysteresis comparator circuit 3, ensuring that the PWM drive signal is consistent with the input PWM control signal, preventing dangerous conditions such as mis-turn on, and extending the system's lifespan.

[0079] Furthermore, since the inverter circuit 8 is small in size and low in cost, adding an inverter circuit will not have a substantial impact on the size and cost of the overall system. The inverter circuit 8 in this disclosure can adopt any circuit structure with inverting function, and this disclosure does not impose any restrictions on it.

[0080] Based on the same inventive concept, this disclosure also provides an automobile that includes a PTC heating control system, which can be any of the PTC heating control systems provided in the preceding embodiments.

[0081] In specific applications, PTC heating control systems can be used for seat heating, rearview mirror heating, air conditioning heating, and more. The vehicle's control system can send PWM control signals to the corresponding PTC heating control system to control it to perform heating and adjust the power output.

[0082] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A PTC heater control system based on PWM control, characterized in that, include: A PWM control signal receiver capable of receiving PWM control signals input from outside the system; A PTC drive circuit capable of outputting a corresponding PTC drive signal based on the received PWM control signal; A hysteresis comparator circuit is disposed between the PWM control signal receiving terminal and the PTC drive circuit. The inverting input terminal of the hysteresis comparator circuit is connected to the PWM control signal receiving terminal, and the output terminal of the hysteresis comparator circuit is connected to the PTC drive circuit.

2. The PTC heater control system according to claim 1, characterized in that, Also includes: The inverter circuit is configured such that the output of the hysteresis comparator circuit is connected to the PTC drive circuit, the input of the inverter circuit is connected to the output of the comparator circuit, and the output of the inverter circuit is connected to the PTC drive circuit.

3. The PTC heater control system according to claim 1, characterized in that, The hysteresis comparator circuit includes: an operational amplifier, a reference voltage supply circuit, a negative feedback circuit, an input noise reduction circuit, an input protection circuit, and an output noise reduction circuit; The reference voltage supply circuit is connected to the non-inverting input of the operational amplifier; The negative feedback circuit is connected to the output terminal and the inverting input terminal of the operational amplifier; The input noise reduction circuit and the input protection circuit are connected in series between the input terminal of the hysteresis comparator circuit and the inverting input terminal of the negative feedback circuit. The output terminal of the operational amplifier is connected to the output terminal of the hysteresis comparator circuit through the output noise reduction circuit.

4. The PTC heater control system according to claim 3, characterized in that, The reference voltage supply circuit includes a first resistor, a second resistor, and a third resistor. The first end of the first resistor is connected to a preset working voltage terminal. The second end of the first resistor is connected to the first end of the second resistor and the first end of the third resistor. The second end of the second resistor is grounded. The second end of the third resistor is connected to the non-inverting input terminal of the operational amplifier. And / or, The negative feedback circuit includes a fourth resistor and a fifth resistor. The first end of the fourth resistor is connected to the inverting input terminal of the operational amplifier, the second end of the fourth resistor is connected to the first end of the fifth resistor, and the second end of the fifth resistor is connected to the output terminal of the operational amplifier. And / or, The input noise reduction circuit includes a sixth resistor, a seventh resistor, and a first capacitor. The first end of the sixth resistor is connected to the input terminal of the hysteresis comparator circuit, and the second end of the sixth resistor is grounded. The first end of the seventh resistor is connected to the input terminal of the hysteresis comparator circuit, and the second end of the seventh resistor is connected to the input protection circuit. The first end of the first capacitor is connected to the input terminal of the hysteresis comparator circuit, and the second end of the first capacitor is grounded. And / or, The input protection circuit includes a first diode, a second diode, and a third diode. The cathode of the first diode is connected to the input noise reduction circuit, and the anode of the first diode is grounded. The cathode of the second diode is connected to a preset protection voltage supply terminal, and the anode of the second diode is connected to the non-inverting input terminal of the operational amplifier and the input noise reduction circuit. The cathode of the third diode is connected to the protection voltage supply terminal, and the anode of the third diode is grounded. And / or, The output noise reduction circuit includes an eighth resistor, a ninth resistor, and a second capacitor. The first end of the eighth resistor is connected to the output terminal of the operational amplifier, and the second end of the eighth resistor is grounded. The first end of the ninth resistor is connected to the output terminal of the operational amplifier, and the second end of the ninth resistor is connected to the output terminal of the hysteresis comparator circuit. The first end of the second capacitor is connected to the output terminal of the hysteresis comparator circuit, and the second end of the second capacitor is grounded.

5. The PTC heater control system according to any one of claims 1 to 4, characterized in that, Also includes: First power module, low dropout linear regulator and isolated boost circuit; The first power module is connected to the low dropout linear regulator and the isolation boost circuit respectively, and is able to provide a first operating voltage to the low dropout linear regulator and the isolation boost circuit respectively; The low-dropout linear regulator is connected to the PTC drive circuit and can generate a second operating voltage based on the first operating voltage, and provide the second operating voltage to the PTC drive circuit. The second operating voltage is less than the first operating voltage. The isolation boost circuit is connected to the PTC drive circuit and can generate a third working voltage based on the second working voltage, and provide the third working voltage to the PTC drive circuit. The third working voltage is greater than the first working voltage.

6. The PTC heater control system according to claim 5, characterized in that, The first power module includes: a first power supply and a power filter; The power filter is connected to the first power supply, the low-dropout linear regulator, and the isolation boost circuit, and can filter the voltage signal output by the first power supply and output the first operating voltage.

7. The PTC heater control system according to any one of claims 1 to 4, characterized in that, Also includes: A second power supply and at least one PTC heating circuit, wherein the PTC heating circuit is disposed between the second power supply and the ground terminal; The second power source can provide a fourth operating voltage to the PTC heating circuit; The PTC heating circuit includes a PTC heating load and a switching transistor connected in series. The switching transistor is connected to the output terminal of the PTC driving circuit and can control the on / off state of the PTC heating circuit according to the PTC driving signal output by the PTC driving circuit.

8. The PTC heater control system according to claim 7, characterized in that, The switching transistor is an insulated gate bipolar transistor.

9. The PTC heater control system according to claim 1, characterized in that, The PTC drive circuit is an isolated driver.

10. A car, characterized in that, include: The PTC heating control system as described in any one of claims 1 to 9.

Images