NTC and relay parallel control circuit

Abstract

The utility model discloses an NTC and relay parallel control circuit, which comprises an NTC protection circuit and a relay control circuit, the NTC protection circuit comprises a thermistor NTC1, the relay control circuit comprises a relay RY1, and the relay RY1 is connected in parallel with two ends of the thermistor NTC1. A control signal enables a collector electrode and an emitter electrode of an NPN triode Q5 to be conducted, a relay RY1 is closed, a thermistor NTC1 is short-circuited, current does not flow through the thermistor NTC1 and flows away through the relay RY1, the problems that circuit design is complex, troubleshooting is difficult, and energy loss is large are solved, safety and efficiency of the circuit are improved, and energy consumption is reduced.

Description

Technical Field

[0001] The utility model relates to the field of emergency protection circuits, and particularly to an NTC and relay parallel control circuit. Background Technique

[0002] The NTC thermistor is a resistor with a negative temperature coefficient characteristic, and its resistance value decreases with the increase of temperature. When an electronic device starts, due to the sudden access of the power supply, the filter capacitor needs to be quickly charged, and this process is often accompanied by a huge inrush current. In the circuit, the NTC thermistor is connected in parallel to the power supply or the motor power supply circuit, and its resistance value changing with temperature is used to limit the inrush current during startup. The relay is energized after the circuit is stable, short-circuiting the NTC, enabling it to exit the working state and have time to cool down. In this way, when starting next time, the NTC can quickly restore its high resistance state and play the current-limiting role again.

[0003] The traditional NTC and relay parallel control circuit has certain advantages in protecting electronic devices and components, but there are also defects and disadvantages such as complex circuit design, difficult fault troubleshooting, and energy loss.

[0004] An "overshoot protection circuit and switching power supply circuit" disclosed in a Chinese patent document, with the publication number CN220139235U, includes a direct current input terminal, a surge protection resistor, a filtering module, and a relay; one end of the surge protection resistor is connected to the direct current input terminal, the other end of the surge protection resistor is connected to the filtering module, and the surge protection resistor is also grounded through the connected filtering module. The relay is connected in parallel with the surge protection resistor; the overshoot protection circuit further includes a main controller, one end of the coil of the relay is connected to the power supply, and the other end of the relay is connected to the main controller. This circuit design is complex and consumes more energy. Summary of the Invention

[0005] The utility model mainly solves problems such as complex circuit design, difficult fault troubleshooting, and large energy loss, and provides an NTC and relay parallel control circuit to reduce power loss and thus reduce energy loss.

[0006] To achieve the above object, the following technical solutions are proposed:

[0007] An NTC and relay parallel control circuit includes an NTC protection circuit and a relay control circuit. The NTC protection circuit includes a thermistor NTC1, and the relay control circuit includes a relay RY1. The relay RY1 is connected in parallel across the two ends of the thermistor NTC1.

[0008] When high-power electricity consumption is encountered, the control signal causes the collector and emitter of the NPN transistor Q5 to conduct, the relay RY1 is energized, and the thermistor NTC1 is short-circuited, so that the current does not flow through the thermistor NTC1 and flows away through the relay RY1, thereby reducing power loss and further reducing energy loss.

[0009] Preferably, one end of the thermistor NTC1 is connected to a rectifier filter circuit, and the rectifier filter circuit is connected to the power input circuit. The rectifier filter circuit can convert the AC signal into a stable DC signal and remove or weaken the high-frequency noise and harmonic signals in the circuit to improve the performance and stability of the circuit.

[0010] Preferably, the input end of the relay RY1 is connected to the output end of the transistor Q5, and the transistor Q5 is connected to an RC circuit. The charging and discharging of the capacitor in the RC circuit produces a delay effect to avoid damage to the components at the moment of power-on.

[0011] Preferably, the rectifier filter circuit includes a rectifier bridge circuit. The rectifier bridge circuit is connected to an inductor L. Capacitor C21 and capacitor C22 are connected in parallel at both ends of the inductor. The output end of the inductor L is connected to the thermistor NTC1 to ensure a smooth and stable DC voltage output, remove noise, and improve the filtering effect and stability.

[0012] Preferably, one end of the coil of the relay RY1 is connected to the power supply, and the other end of the coil of the relay RY1 is connected to the collector of the transistor Q5 to control the energization of the relay RY1 to short-circuit the relay NTC1.

[0013] Preferably, a resistor R33 is connected in parallel between the base and the collector of the transistor Q5. One end of the resistor R33 is connected to the input end of the transistor Q5, and the other end is grounded to the emitter of the transistor Q5 to avoid high-voltage breakdown of the transistor Q5.

[0014] Preferably, the RC circuit includes a resistor R23 and a capacitor C1. The output end of the resistor R23 is connected to the transistor Q5. The input end of the resistor R23 is connected to the output end of the capacitor C1. The input end of the capacitor C1 receives the control signal. The charging and discharging process of the capacitor is used to produce a delay effect, which can play a better protection role for high-power circuits.

[0015] Preferably, two parallel resistors R12 and R11 are connected to the input end of the relay RY1. The input end of the resistor R12 is connected to the +15V voltage, which is used to limit the passing current, protect other components from damage caused by excessive current, and adjust the voltage.

[0016] Preferably, a zener diode D1 is connected in parallel across the relay RY1 to provide a stable voltage output when the voltage exceeds its reverse breakdown voltage, thereby protecting other components from voltage fluctuations. Brief Description of the Drawings

[0017] Figure 1 This is a schematic diagram of a module of a control circuit with an NTC and a relay connected in parallel according to the present invention.

[0018] Figure 2 This is a circuit diagram of a control circuit with an NTC and a relay connected in parallel according to the present invention.

[0019] Figure 3 This is a schematic diagram of the connection between the relay and the control circuit of a control circuit with an NTC and a relay connected in parallel according to the present invention.

[0020] Figure 4 This is a schematic diagram of the filter circuit of a control circuit with an NTC and a relay connected in parallel according to the present invention. Detailed Embodiment

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] The specific embodiments of the present invention are as follows:

[0023] The present invention discloses a control circuit with an NTC and a relay connected in parallel. Its module schematic diagram is as Figure 1 shown.

[0024] It includes a thermistor NTC1. A relay RY1 is connected in parallel across the two ends of the thermistor. One end of the thermistor NTC1 is connected to a rectifier filter circuit, which is connected to a power input circuit through the rectifier filter circuit. The rectifier filter circuit includes a rectifier bridge circuit. The rectifier bridge circuit is connected to an inductor L. Capacitor C21 and capacitor C22 are connected in parallel across the two ends of the inductor. The output end of the inductor L is connected to the thermistor NTC1. The input end of the relay RY1 is connected to the output end of a triode Q5. The triode Q5 is connected to an RC circuit. The RC circuit includes a resistor R23 and a capacitor C1. The output end of the resistor R23 is connected to the triode Q5. The input end of the resistor R23 is connected to the output end of the capacitor C1. The input end of the capacitor C1 is connected to the control signal.

[0025] When high-power electricity consumption occurs, the control signal causes the collector and emitter of the NPN transistor Q5 to conduct, the relay RY1 to close, short-circuit the thermistor NTC1, so that the current does not flow through the thermistor NTC1 and flows away through the relay RY1, thereby reducing power loss and further reducing energy loss.

[0026] The thermistor NTC1 is used to suppress surges. NTC stands for negative temperature coefficient, and its resistance value decreases as the temperature rises. When an electronic device starts up, due to the sudden connection of the power supply, the filter capacitor needs to be quickly charged, and this process is often accompanied by a huge surge current. Surge current usually occurs when the power supply is suddenly connected. Since the filter capacitor needs to be quickly charged, the instantaneous current may far exceed the normal working current, posing a threat to the components in the circuit. In the circuit, the NTC thermistor is connected in parallel in the power supply or motor power supply loop, and uses its characteristic that the resistance value changes with temperature to effectively limit the surge current at startup and protect the safety of the circuit.

[0027] When an electronic device starts up, the NTC thermistor is connected in parallel in the power supply or motor power supply loop. Since the NTC resistance value is large in the initial state, it can effectively limit the magnitude of the current passing through the circuit, thereby slowing down the charging speed of the filter capacitor and suppressing the generation of surge current. As the capacitor charging process progresses, the temperature in the circuit gradually rises, and the NTC resistance value decreases accordingly, allowing more current to pass through until it reaches a stable operating state. This process not only protects the circuit components from damage caused by surge current but also ensures that the device can start up smoothly.

[0028] A relay is a switching device that can control the on / off of a larger current with a smaller current. It consists of a coil, contacts, etc. When enough current is passed through the coil, a magnetic field will be generated to attract the contacts to close or open, thereby changing the on / off state of the circuit. When an electronic device enters a high-power working state or encounters a scenario that requires a high current supply, the control signal will activate the transistor Q5, causing its collector and emitter to conduct. Subsequently, the current flows through the transistor Q5 to the driving coil of the relay RY1, causing the relay RY1 to close. At this time, the contacts of the relay RY1 short-circuit the thermistor NTC, and the current bypasses the NTC and directly flows away through the relay RY1. This design can reduce the power loss caused by the existence of the thermistor NTC1, and further reduce the energy loss. At the same time, at the moment of high-power access, the short-circuit function of the relay RY1 can also effectively avoid the impact and damage to the circuit components.

[0029] The resistors R11 and R12 connected in parallel to the circuit mainly function to limit the magnitude of the current passing through the circuit and prevent other circuit components from being damaged due to excessive current. In addition, the working state of the circuit can be optimized by adjusting the voltage.

[0030] The rectifier and filter circuit includes a rectifier bridge circuit. The rectifier bridge circuit is connected to an inductor L. Capacitors C21 and C22 are connected in parallel across the two ends of the inductor. The output end of the inductor L is connected to the thermistor NTC1. It converts the AC signal into a stable DC signal, removes or weakens the high-frequency noise and harmonic signals in the circuit, improves the purity of the signal and the anti-interference ability of the system, so as to further enhance the anti-interference ability and stability of the circuit.

[0031] The relay RY1 is connected to the triode Q5 and is responsible for receiving the control signal and converting it into a control instruction for the relay RY1. The control signal is usually output from the I / O port of a microcontroller (MCU) or provided by other main control units. These signals are transmitted to the base of the triode Q5 after appropriate processing (such as level conversion, filtering, etc.). When the control signal is at a high level, the triode Q5 enters the conducting state, allowing current to flow through the resistor R33 between its collector and emitter to the driving coil of the relay RY1. In this way, the relay RY1 will receive sufficient energy and pull in.

[0032] It should be noted that the NPN-type triode Q5 is used as the driving element of the relay RY1 in this design, which has a high input impedance, a low output impedance and good current amplification ability. In addition, in order to further improve the reliability and stability of the circuit, a field effect transistor (FET) or MOS transistor, etc. can be used to replace the triode as the driving element.

[0033] In summary, the working process of a control circuit with an NTC and a relay in parallel of the present utility model is roughly as follows: When the electronic device starts up, the NTC1 uses the characteristic that its resistance changes with temperature to limit the inrush current; when there is high-power electricity consumption, the control signal activates the triode Q5 to make the relay RY1 pull in, short-circuiting the thermistor NTC1 to reduce power loss; at the same time, the protection circuit ensures that the current flows within a reasonable range to avoid component damage. This design not only improves the safety and efficiency of the circuit but also reduces energy consumption and has significant application value.

[0034] The present utility model discloses a control circuit with an NTC and a relay in parallel. Its circuit diagram is as Figure 2 shown.

[0035] It includes an NTC protection circuit and a relay control circuit. The NTC protection circuit includes a thermistor NTC1. The relay control circuit includes a relay RY1. The relay RY1 is connected in parallel across the two ends of the thermistor NTC1. When there is high-power electricity consumption, the control signal makes the collector and emitter of the NPN transistor Q5 conduct, and the relay RY1 pulls in, short-circuiting the thermistor NTC1 so that the current does not flow through the thermistor NTC1 and flows away through the relay RY1, thereby reducing power loss and further reducing energy loss.

[0036] An NTC thermistor, as a temperature-sensitive component, its resistance value changes significantly with temperature. When the temperature rises, the resistance value of the NTC will drop rapidly, and vice versa. This characteristic makes the NTC often used as an over-temperature protection or current-limiting component in electronic devices.

[0037] In this circuit design, NTC1 is placed at the front end of the power input circuit. Its main function is to limit the magnitude of the current flowing into the power input circuit, preventing equipment damage or fire risks caused by excessive current.

[0038] One end of the relay RY1 is connected to the parallel combination of resistor R12 and resistor R11, providing the necessary driving voltage for the relay. Resistor R11 is connected in parallel across both ends of resistor R12, forming a voltage-dividing circuit. This design not only helps to limit the magnitude of the current passing through resistor R12 and relay RY1, effectively preventing component damage due to excessive current, but also can adjust the voltage applied to relay RY1 to a certain extent to ensure its stable and reliable operation.

[0039] Through the relay control circuit, dynamic short-circuit control of NTC1 is achieved. When the circuit encounters high-power electricity consumption, the control signal will activate the NPN transistor Q5, making its collector and emitter conduct. This conducting state then drives the relay RY1 to pull in, switching the current path originally flowing through the thermistor NTC1 to the relay RY1, achieving a short circuit of NTC1. It can quickly bypass NTC1 from the circuit when needed, thus avoiding power loss caused by the resistance of NTC itself. At the same time, since the on-resistance of the relay RY1 is much smaller than the resistance value of NTC1 at normal operating temperature, the loss generated when the current flows through the relay RY1 is also relatively low. In this way, the circuit can not only operate efficiently under high-power loads but also respond quickly to protect the circuit safety when necessary.

[0040] One end of the thermistor NTC1 is connected to a rectifier filter circuit. The rectifier filter circuit includes a rectifier bridge circuit. The rectifier bridge circuit is connected to an inductor L. Capacitor C21 and capacitor C22 are connected in parallel across both ends of the inductor. The output end of the inductor L is connected to the thermistor NTC1; it converts the AC signal into a stable DC signal and removes or weakens the high-frequency noise and harmonic signals in the circuit, improving the purity of the signal and the anti-interference ability of the system to further enhance the anti-interference ability and stability of the circuit.

[0041] The other end of the relay RY1 is connected to the collector of the transistor Q5, controlling the pulling-in of the relay RY1 to short-circuit the relay NTC1.

[0042] An RC circuit is provided between the control signal and the triode Q5. The RC circuit includes a resistor R23 and a capacitor C1. The output end of the resistor R23 is connected to the triode Q5. The input end of the resistor R23 is connected to the output end of the capacitor C1. The input end of the capacitor C1 is connected to the control signal. By using the charging and discharging process of the capacitor to produce a delay effect, it can play a better protective role for high-power circuits.

[0043] The triode Q5 serves as the control switch of the relay RY1, and its base receives the control signal through the resistor R23. When the control signal is at a high level, the resistor R23 provides sufficient bias voltage for the triode Q5, causing it to enter the saturation conduction state. At this time, the resistance between the collector and the emitter of the triode Q5 is extremely low, almost equivalent to a wire, thereby driving the relay RY1 to pull in. Conversely, when the control signal is at a low level, the triode Q5 is cut off and does not conduct, and the relay RY1 also disconnects accordingly. This way of dynamically adjusting the state of the triode Q5 through the control signal realizes the precise control of the relay RY1.

[0044] A resistor R33 is connected in parallel between the base and the emitter of the triode Q5. One end of the resistor R33 is connected to the input end of the triode Q5, and the other end is grounded through the emitter of the triode Q5. Its main function is to protect Q5 from the risk of high-voltage breakdown. In the event of an abnormal circuit situation, such as when the control signal suddenly rises to a dangerous level, R33 can quickly divert the excess current to the ground, thereby preventing too high a voltage from directly acting on Q5 and causing its damage.

[0045] The zener diode D1 is connected in parallel across the relay RY1. Its reverse breakdown voltage is set to the maximum operating voltage allowed by the circuit. When the voltage in the circuit rises due to some reason and exceeds this threshold, D1 will quickly conduct and clamp the voltage at a stable level. It not only protects the relay RY1 and other components from damage caused by excessive voltage, but also ensures that the circuit can still maintain a certain stability under abnormal conditions.

[0046] The practical application scope of this circuit design is extensive, especially suitable for electronic devices that need to handle high-power loads and have high requirements for energy efficiency and safety. For example, in the fields of industrial automation control systems, power electronic conversion devices, and high-end household appliances, this circuit can play an important role. By dynamically adjusting the current path and reducing power loss, this circuit not only improves the overall energy efficiency of the device, but also extends the service life of the device, and the circuit is simple, reducing the maintenance cost.

[0047] The present utility model is not limited to the specific technical solutions described in the above embodiments. In addition to the above embodiments, the present utility model may also have other implementation manners. For those skilled in the art, any technical solutions formed by making any modifications, equivalent replacements, improvements, etc. within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. An NTC and relay parallel control circuit, characterized in that: The invention comprises an NTC protection circuit and a relay control circuit. The NTC protection circuit comprises a thermistor NTC1. The relay control circuit comprises a relay RY1. The relay RY1 is connected in parallel to two ends of the thermistor NTC1.

2. The NTC and relay parallel control circuit according to claim 1, characterized in that: The thermistor NTC1 and the relay RY1 are connected in parallel to a rectifier and filter circuit, and the rectifier and filter circuit is electrically connected to a power input circuit.

3. The NTC and relay parallel control circuit according to claim 1 or 2, characterized in that: The input end of the relay RY1 is connected to the output end of the transistor Q5, and the transistor Q5 is connected to an RC circuit.

4. The NTC and relay parallel control circuit according to claim 2, characterized in that: The rectification and filtering circuit includes a rectifier bridge circuit, the rectifier bridge circuit is connected to an inductor L, capacitors C21 and C22 are connected in parallel at both ends of the inductor L, and an output end of the inductor L is connected to the thermistor NTC1.

5. The NTC and relay parallel control circuit according to claim 1, 2 or 4, characterized in that: One end of the coil of the relay RY1 is connected to a power source, and the other end of the coil of the relay RY1 is connected to the collector of the transistor Q5.

6. The NTC and relay parallel control circuit according to claim 3, characterized in that: One end of the resistor R33 is connected to the input end of the transistor Q5 , and the other end of the resistor R33 is grounded to the emitter of the transistor Q5 .

7. The NTC and relay parallel control circuit according to claim 3, characterized in that: The RC circuit includes a resistor R23 and a capacitor C1. The output end of the resistor R23 is connected to the transistor Q5. The transistor Q5 serves as a control switch of the relay RY1. Its base receives a control signal through the resistor R23. The input end of the resistor R23 is connected to the output end of the capacitor C1. The input end of the capacitor C1 receives a control signal.

8. The NTC and relay parallel control circuit according to claim 4, characterized in that: The input end of the relay RY1 is connected to two parallel resistors R12 and a resistor R11, and the input end of the resistor R12 is connected to a +15V voltage.

9. The NTC and relay parallel control circuit according to claim 4, characterized in that: The two ends of the relay RY1 are connected in parallel with a voltage regulator diode D1.

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