Temperature control and thermal fuse dual protection system

Abstract

The utility model discloses a temperature control and thermal fuse dual protection system, which relates to the field of overheat protection circuits and comprises a temperature detection module, a judgment module, a first switch module and a fuse. The temperature detection module, the judgment module and the first switch module are sequentially connected; the heating element is connected with a power supply through the first switch module; the temperature detection module is used for collecting a temperature signal of a heating element, the judgment module has a critical temperature threshold value, and when the judgment module judges that the temperature signal is smaller than or equal to the critical temperature threshold value, the judgment module outputs a high-level signal, and the first switch module is switched on; and the fuse is connected in a power supply circuit of the heating element and is attached to the heating element. According to the utility model, dual protection is provided for the heating element, and on one hand, a power supply of the heating element is cut off through the first switch module based on a temperature detection result; and the other mode is that the power supply of the heating element is cut off through the fuse by virtue of the heat of the heating element.

Description

Technical Field

[0001] The utility model relates to the field of overheat protection circuits, and more particularly to a temperature control and thermal fuse dual protection system. Background Art

[0002] Heating devices are high-power devices that generate significant heat during operation. They are also typically used in high-temperature environments. To ensure that the operating temperature of the heating device does not exceed its operating range, heating devices are typically equipped with an overheat protection circuit. If the operating temperature of the heating device exceeds the set range, the overheat protection circuit disconnects the heating device's circuit, causing it to cease operation.

[0003] Chinese patent CN105610126A provides a network device overheat protection circuit, which is provided with a digital conversion unit, a temperature sampling unit, a self-locking module, a PMOS tube and a resistor R22. The PMOS tube remains in a conductive state in the circuit of the network device. The temperature sampling unit includes a resistor R11, a thermistor R8, a resistor R10 and a resistor R9. The digital conversion unit includes a resistor R18, a resistor R19 and a comparator U4; the self-locking module includes a diode D6, a resistor R12 and a unidirectional thyristor D4; the resistors R11 and R10 in the temperature sampling unit divide the voltage, the ... Resistors R8 and R9 divide the voltage. The non-inverting input of the comparator U4 is connected between the thermistor R8 and the resistor R9 through the resistor R18. The inverting input of the comparator U4 is connected between the resistor R11 and the resistor R10. The resistor R19 is connected between the inverting input and the output of the comparator U4. The output of the comparator U4 triggers the one-way thyristor D4 to turn on through the diode D6 and the resistor R12. After the one-way thyristor D4 is turned on, the G pole of the PMOS tube is connected to the turn-on voltage transmitted through the one-way thyristor D4 and the resistor R22. The PMOS tube is disconnected, cutting off the circuit of the network device.

[0004] Although this circuit can achieve the effect of overheat protection, once the thermistor fails, the entire overheat protection circuit will fail. Utility Model Content

[0005] In view of the problem that once the thermistor failure occurs in the existing overheat protection circuit, the entire overheat protection circuit will fail. The purpose of the present utility model is to provide a dual protection system of temperature control and thermal fuse, which includes a temperature detection module, a judgment module, a first switch module and a fuse. The temperature detection module, the judgment module and the first switch module are connected in sequence, and the heating element is connected to the power supply through the first switch module. The temperature detection module is used to collect the temperature signal of the heating element. The judgment module has a critical temperature threshold. When the judgment module determines that the temperature signal is less than or equal to the critical temperature threshold, the judgment module outputs a high-level signal and the first switch module is turned on. When the judgment module determines that the temperature signal is greater than the critical temperature threshold, the judgment module outputs a low-level signal and the first switch module is turned off. The fuse is connected to the power supply circuit of the heating element, and the fuse is in contact with the heating element.

[0006] The present invention is further configured as follows: the first switch module includes an NMOS tube Q1, a PMOS tube Q2 and a resistor R4, the gate of the NMOS tube Q1 is connected to the judgment module, the source of the NMOS tube Q1 is grounded, the drain of the NMOS tube Q1 is connected to the gate of the PMOS tube Q2, the source of the PMOS tube Q2 is connected to the power supply of the heating element, and the drain of the PMOS tube Q2 is connected to the heating element; and the two ends of the resistor R4 are respectively connected to the gate and source of the PMOS tube Q2.

[0007] The present invention is further configured as follows: the first switch module further includes a resistor R5, and the drain of the NMOS tube Q1 is connected to the gate of the PMOS tube Q2 via the resistor R5.

[0008] The present invention is further configured as follows: the first switch module further includes a capacitor C1 and a capacitor C2, the two ends of the capacitor C1 are respectively connected to the gate and source of the NMOS transistor Q1, and the two ends of the capacitor C2 are respectively connected to the gate and source of the PMOS transistor Q2.

[0009] The present invention is further configured as follows: the first switch module further includes a resistor R6, and two ends of the resistor R6 are respectively connected to the gate and source of the NMOS transistor Q1.

[0010] The present invention is further configured to include an inductor FB1 , and the judgment module is connected to the gate of the NMOS tube Q1 via the inductor FB1 .

[0011] The present invention is further configured to include: a second switch module, the second switch module including an NMOS tube Q3 and a resistor R8, the gate of the NMOS tube Q3 is connected to the resistor R8, the resistor R8 is connected to the external PWM signal, the source of the NMOS tube Q3 is grounded, and the drain of the NMOS tube Q3 is connected between the first switch module and the heating element.

[0012] The present invention is further configured as follows: the second switch module further includes a capacitor C3 and a resistor R9, the two ends of the capacitor C3 are respectively connected to the gate and source of the NMOS transistor Q3, and the two ends of the resistor R9 are respectively connected to the gate and source of the NMOS transistor Q3.

[0013] The present invention is further configured to include: a first filter, and the temperature detection module is connected to the judgment module via the first filter.

[0014] The utility model is further configured as follows: the temperature detection module includes a resistor R1 and an NTC resistor, and the judgment module includes a resistor R2, a resistor R3, and a comparator. Resistors R1 and R2 are connected to the same power supply, resistor R1 and the NTC resistor are connected in series, resistor R2 and resistor R3 are connected in series, and the NTC resistor and resistor R3 are grounded separately. Resistors R1 and R2 have the same resistance value, the resistance value of resistor R3 is equal to the resistance value of the NTC resistor at the critical temperature, and the NTC resistor is in contact with the heating element. The non-inverting input terminal of the comparator is connected between resistor R1 and the NTC resistor. The inverting input terminal of the comparator is connected between resistor R2 and resistor R3. The output terminal of the comparator is connected to the first switch module.

[0015] In summary, the present invention has the following beneficial effects compared with the prior art: the present system provides dual protection for the heating element. One is based on the temperature detection result. When the real-time detection temperature of the heating element is greater than the set critical temperature, the circuit connection between the heating element and the power supply is cut off. The other is when any part of the temperature detection module, the judgment module and the first switch module fails, the heat of the heating element itself is used to melt the fuse in the fuse, thereby cutting off the power circuit in the heating element. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the structure of the embodiment. DETAILED DESCRIPTION

[0017] The technical solution of the present invention will be clearly described below in conjunction with the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model.

[0018] It should be noted that the terms "center", "up", "down", "horizontal", "left", "right", "front", "back", "lateral", "longitudinal", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0019] The term "NTC resistor" stands for negative temperature coefficient thermistor.

[0020] Example

[0021] like Figure 1 As shown, this embodiment provides a temperature control and thermal fuse dual protection system, which includes a temperature detection module, a judgment module, a first switch module and a fuse. The temperature detection module, the judgment module and the first switch module are connected in sequence, and the heating element is connected to the power supply through the first switch module. The temperature detection module is used to collect the temperature signal of the heating element. The judgment module has a critical temperature threshold. When the judgment module determines that the temperature signal is less than or equal to the critical temperature threshold, the judgment module outputs a high-level signal and the first switch module is turned on. When the judgment module determines that the temperature signal is greater than the critical temperature threshold, the judgment module outputs a low-level signal and the first switch module is turned off. The fuse is connected to the power supply circuit of the heating element, and the fuse is in contact with the heating element. The fuse and the heating element are not shown in the figure.

[0022] This system provides dual protection for the heating element. One is based on the temperature detection results. When the real-time detection temperature of the heating element is greater than the set critical temperature, the circuit connection between the heating element and the power supply is cut off. The other is when any part of the temperature detection module, the judgment module and the first switch module fails, the heat of the heating element itself is used to melt the fuse in the fuse, thereby cutting off the power circuit in the heating element.

[0023] Specifically, the temperature detection module includes a resistor R1 and an NTC resistor, and the judgment module includes a resistor R2, a resistor R3, and a comparator. Resistors R1 and R2 are connected to the same power supply, resistor R1 and the NTC resistor are connected in series, resistor R2 and resistor R3 are connected in series, and the NTC resistor and resistor R3 are grounded separately. Resistors R1 and R2 have the same resistance value, the resistance value of resistor R3 is equal to the resistance value of the NTC resistor at a critical temperature, and the NTC resistor is in contact with the heating element. The non-inverting input terminal of the comparator is connected between resistor R1 and the NTC resistor. The inverting input terminal of the comparator is connected between resistor R2 and resistor R3. The output terminal of the comparator is connected to the first switching module. When the temperature of the heating element is lower than the set critical temperature, the resistance value of the NTC resistor is greater than the resistance value of R3, the voltage at the non-inverting input terminal of the comparator is greater than the voltage at the inverting input terminal of the comparator, and the output terminal of the comparator outputs a high-level signal. When the temperature of the heating element is higher than or equal to the set critical temperature, the resistance of the NTC resistor is less than or equal to the resistance of R3, the voltage at the positive input of the comparator is less than or equal to the voltage at the inverting input of the comparator, and the comparator output outputs a low level signal.

[0024] Specifically, the first switch module includes an NMOS transistor Q1, a PMOS transistor Q2, and a resistor R4. The gate of the NMOS transistor Q1 is connected to the judgment module, the source of the NMOS transistor Q1 is grounded, the drain of the NMOS transistor Q1 is connected to the gate of the PMOS transistor Q2, the source of the PMOS transistor Q2 is connected to the power supply of the heating element, and the drain of the PMOS transistor Q2 is connected to the heating element. The two ends of the resistor R4 are respectively connected to the gate and source of the PMOS transistor Q2 to limit the current passing through the gate of the PMOS transistor Q2 and protect the PMOS transistor Q2. When the temperature of the heating element is lower than a set critical temperature, the comparator output terminal outputs a high-level signal, the NMOS transistor Q1 and the PMOS transistor Q2 are turned on, and the heating element operates normally. When the temperature of the heating element is higher than or equal to the set critical temperature, the comparator output terminal outputs a low-level signal, the NMOS transistor Q1 and the PMOS transistor Q2 are turned off, and the heating element is powered off. In this embodiment, the NMOS transistor Q1 and the PMOS transistor Q2 can be directly controlled by the level signal of the judgment module, eliminating the need for an additional power supply and simplifying the structure of the first switch module. Furthermore, the NMOS transistor Q1 and the PMOS transistor Q2 have a high response speed, enabling rapid temperature control of the heating element.

[0025] Specifically, the first switch module further includes a resistor R5, through which the drain of the NMOS transistor Q1 is connected to the gate of the PMOS transistor Q2. The resistor R5 can limit the current passing through the NMOS transistor Q1, reducing the impact of transient current on the NMOS transistor Q1 when the NMOS transistor Q1 and the PMOS transistor Q2 are turned on, thereby protecting the NMOS transistor Q1.

[0026] Specifically, the first switch module also includes capacitors C1 and C2. The two ends of capacitor C1 are connected to the gate and source of NMOS transistor Q1, respectively, and the two ends of capacitor C2 are connected to the gate and source of PMOS transistor Q2, respectively. Capacitor C1 can filter out high-frequency noise at NMOS transistor Q1 and reduce the impact of transient voltage changes on NMOS transistor Q1 when NMOS transistor Q1 is turned on. Capacitor C2 can filter out high-frequency noise at PMOS transistor Q2 and reduce the impact of transient voltage changes on PMOS transistor Q2 when PMOS transistor Q2 is turned on. Resistor R4 can reduce the overreaction of capacitor C2 to voltage changes, thereby improving circuit stability.

[0027] Specifically, the first switch module further includes a resistor R6, the two ends of which are connected to the gate and source of the NMOS transistor Q1, respectively. The resistor R6 can reduce the over-reaction of the capacitor C1 to voltage changes and improve the stability of the circuit.

[0028] This embodiment also includes an inductor FB1, through which the judgment module is connected to the gate of the NMOS transistor Q1. The inductor FB1 can limit rapidly changing current, reduce high-frequency interference, stabilize the on and off operations of the NMOS transistor Q1, and reduce false triggering of the NMOS transistor Q1 caused by noise.

[0029] This embodiment also includes a second switch module, one end of which is grounded and the other end of which is connected between the first switch module and the heating element. The second switch module is controlled to turn on or off by an external PWM signal. When the first switch module is on and the second switch module is off, the heating element operates normally. When the second switch module is on, the heating element is powered off. An operator can control the second switch module to turn off power to the heating element using an external PWM signal.

[0030] Specifically, the second switch module includes an NMOS transistor Q3 and a resistor R8. The gate of the NMOS transistor Q3 is connected to the resistor R8, which is connected to the external PWM signal. The source of the NMOS transistor Q3 is grounded, and the drain of the NMOS transistor Q3 is connected between the first switch module and the heating element. When the external PWM signal outputs a high level, the NMOS transistor Q3 is turned on. When the external PWM signal outputs a low level, the NMOS transistor Q3 is turned off.

[0031] Specifically, the second switch module further includes a capacitor C3 and a resistor R9. The two ends of the capacitor C3 are connected to the gate and source of the NMOS transistor Q3, respectively. The capacitor C3 can filter out high-frequency noise at the NMOS transistor Q3 and reduce the impact of transient voltage changes on the NMOS transistor Q3 when the NMOS transistor Q3 is turned on. The two ends of the resistor R9 are connected to the gate and source of the NMOS transistor Q3, respectively. The resistor R9 can reduce the overreaction of the capacitor C3 to voltage changes and improve the stability of the circuit.

[0032] This embodiment further includes a first filter, through which the temperature detection module is connected to the judgment module. The first filter can filter out noise at the temperature detection module, improve the accuracy of the signal input to the judgment module, and reduce the possibility of false triggering of the first switch module.

[0033] Specifically, the first filter includes a capacitor C4 and an inductor FB2. The temperature detection module is connected to the judgment module via the inductor FB2. One end of the capacitor C4 is grounded, and the other end of the capacitor C4 is connected between the inductor FB2 and the judgment module. The capacitor C4 and the inductor FB2 form a simple LC filter. In this embodiment, the comparator's non-inverting input is connected to the junction of the resistor R1 and the NTC resistor via the inductor FB2.

[0034] This embodiment further includes a resistor R10, through which the temperature detection module is connected to the judgment module. Resistor R10 is used to limit the current and voltage input to the non-inverting input terminal of the comparator to protect the comparator and reduce the impact of noise on the comparator. In this embodiment, the two ends of resistor R10 are respectively connected to the first filter and the judgment module.

[0035] This embodiment further includes a capacitor C5 , whose two ends are connected to the two ends of the resistor R3 respectively, so as to reduce the influence of power supply noise and transient voltage on the voltage at the resistor R3 and improve the accuracy and stability of the signal at the inverting input terminal of the comparator.

[0036] This embodiment further includes a resistor R11, through which the inverting input of the comparator is connected to the junction of resistors R2 and R3. Resistor R11 is used to limit the current and voltage input to the inverting input of the comparator to protect the comparator and reduce the impact of noise on the comparator.

[0037] Specifically, the comparator further has a power supply terminal and a ground terminal, and the power supply terminal is connected to an external power supply.

[0038] This embodiment further includes a second filter, the power supply end is connected to the external power supply through the second filter, and the second filter is used to reduce the impact of noise and fluctuation of the external power supply on the comparator, thereby reducing the error of the comparator.

[0039] The second filter includes a capacitor C6 and an inductor FB3. The power supply end is connected to the external power supply through the inductor FB3. One end of the capacitor C6 is grounded, and the other end of the capacitor C6 is connected between the inductor FB3 and the external power supply. The capacitor C6 and the inductor FB3 form a simple LC filter.

[0040] This embodiment further includes a connector HX. The first switch module and the second switch module are both connected to the heating element via the connector HX. That is, the drain of the PMOS transistor Q2 and the drain of the NMOS transistor Q3 are both connected to the connector HX.

[0041] This embodiment also includes a third filter. The first switch module is connected to the heating element through the third filter to reduce transient voltage and transient current caused by the first switch module being turned on and off, thereby protecting the heating element. At the same time, the third filter can also reduce noise in the power supply and reduce the impact of power supply noise on the heating element.

[0042] The third filter includes a capacitor C7 and an inductor FB4. The first switch module is connected to the heating element through the inductor FB4. One end of the capacitor C7 is grounded, and the other end of the capacitor C7 is connected between the inductor FB4 and the heating element. The capacitor C7 and the inductor FB4 form a simple LC filter.

[0043] This embodiment further includes a capacitor C8, one end of which is grounded and the other end of which is connected between the first switch module and the heating element. At least one capacitor C8 is provided. Capacitor C8 can effectively filter out power supply noise, smooth voltage fluctuations, and protect the heating element. In this embodiment, the ungrounded end of capacitor C8 is connected between the first switch module and the third filter to protect the third filter. In this embodiment, two capacitors C8 are provided.

[0044] This embodiment further includes a resistor R12. The second switch module is connected between the first switch module and the heating element via the resistor R12. The resistor R12 is used to limit the current and voltage flowing from the first switch module to the second switch module, thereby protecting the second switch module.

[0045] This embodiment further includes a capacitor C9, one end of which is grounded, and the other end of which is connected between the junction of the first switch module and the heating element and the resistor 12. The capacitor C9 can effectively filter out power supply noise, smooth voltage fluctuations, and protect the second switch module.

[0046] In summary, this system provides dual protection for the heating element. One is based on the temperature detection result. When the real-time detection temperature of the heating element is greater than the set critical temperature, the circuit connection between the heating element and the power supply is cut off. The other is when any part of the temperature detection module, the judgment module and the first switch module fails, the heat of the heating element itself is used to melt the fuse in the fuse, thereby cutting off the power circuit in the heating element.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A temperature control and thermal fuse dual protection system, characterized by: It includes a temperature detection module, a judgment module, a first switch module and a fuse; the temperature detection module, the judgment module and the first switch module are connected in sequence, and the heating element is connected to the power supply through the first switch module; the temperature detection module is used to collect the temperature signal of the heating element, and the judgment module has a critical temperature threshold. When the judgment module determines that the temperature signal is less than or equal to the critical temperature threshold, the judgment module outputs a high-level signal and the first switch module is turned on; when the judgment module determines that the temperature signal is greater than the critical temperature threshold, the judgment module outputs a low-level signal and the first switch module is turned off; the fuse is connected to the power supply circuit of the heating element, and the fuse is in contact with the heating element.

2. The temperature control and thermal fuse dual protection system according to claim 1, characterized in that: The first switch module includes an NMOS transistor Q1, a PMOS transistor Q2 and a resistor R4. The gate of the NMOS transistor Q1 is connected to the judgment module, the source of the NMOS transistor Q1 is grounded, the drain of the NMOS transistor Q1 is connected to the gate of the PMOS transistor Q2, the source of the PMOS transistor Q2 is connected to the power supply of the heating element, and the drain of the PMOS transistor Q2 is connected to the heating element; the two ends of the resistor R4 are respectively connected to the gate and source of the PMOS transistor Q2.

3. The temperature control and thermal fuse dual protection system according to claim 2, characterized in that: The first switch module further includes a resistor R5 , and the drain of the NMOS transistor Q1 is connected to the gate of the PMOS transistor Q2 via the resistor R5 .

4. The temperature control and thermal fuse dual protection system according to any one of claims 2-3, characterized in that: The first switch module further includes a capacitor C1 and a capacitor C2. The two ends of the capacitor C1 are respectively connected to the gate and source of the NMOS transistor Q1. The two ends of the capacitor C2 are respectively connected to the gate and source of the PMOS transistor Q2.

5. The temperature control and thermal fuse dual protection system according to claim 4, characterized in that: The first switch module further includes a resistor R6 , and two ends of the resistor R6 are respectively connected to the gate and source of the NMOS transistor Q1 .

6. The temperature control and thermal fuse dual protection system according to any one of claims 2-3, characterized in that: It also includes an inductor FB1, and the judgment module is connected to the gate of the NMOS tube Q1 through the inductor FB1.

7. The temperature control and thermal fuse dual protection system according to any one of claims 1 to 3, characterized in that: It also includes a second switch module, which includes an NMOS tube Q3 and a resistor R8. The gate of the NMOS tube Q3 is connected to the resistor R8, the resistor R8 is connected to the external PWM signal, the source of the NMOS tube Q3 is grounded, and the drain of the NMOS tube Q3 is connected between the first switch module and the heating element.

8. The temperature control and thermal fuse dual protection system according to claim 7, characterized in that: The second switch module further includes a capacitor C3 and a resistor R9. The two ends of the capacitor C3 are respectively connected to the gate and source of the NMOS transistor Q3. The two ends of the resistor R9 are respectively connected to the gate and source of the NMOS transistor Q3.

9. The temperature control and thermal fuse dual protection system according to any one of claims 1 to 3, characterized in that: It also includes a first filter, and the temperature detection module is connected to the judgment module through the first filter.

10. The temperature control and thermal fuse dual protection system according to any one of claims 1 to 3, characterized in that: The temperature detection module includes a resistor R1 and an NTC resistor, and the judgment module includes a resistor R2, a resistor R3 and a comparator; the resistors R1 and R2 are connected to the same power supply, the resistor R1 and the NTC resistor are connected in series, the resistor R2 and the resistor R3 are connected in series, and the NTC resistor and the resistor R3 are grounded respectively; the resistors R1 and R2 have the same resistance value, the resistance value of the resistor R3 is equal to the resistance value of the NTC resistor at the critical temperature, and the NTC resistor is in contact with the heating element; the non-phase input end of the comparator is connected between the resistor R1 and the NTC resistor; the inverting input end of the comparator is connected between the resistor R2 and the resistor R3; and the output end of the comparator is connected to the first switch module.

Images