Continuously adjustable over-current protection circuit

Abstract

The utility model discloses a continuously adjustable over-current protection circuit, which comprises an operational amplifier N1, an operational amplifier N2 and a voltage comparator N3, a pin 3 of the operational amplifier N1 is connected with a resistor R2, the other end of the resistor R2 is connected with a cathode of a diode V4, an anode of the diode V3, an anode of a diode V2, a capacitor C1, a resistor R1 and a capacitor C2, a cathode of the diode V3 is connected with + 15V voltage, and an anode of the diode V2 is connected with + 15V voltage. The positive electrode of the diode V4 is connected with-15V voltage, and the negative electrode of the diode V2 is connected with the negative electrode of the diode V1. The design has the advantages that: 1, the current protection circuit is adopted, so that a load can be well protected from being damaged, the power supply is not afraid of short circuit and overload, no adverse effect is caused in the short circuit and overload states, and short circuit faults are allowed to be eliminated for a long time; 2, when the current protection gear needs to be adjusted, the potentiometer is convenient and fast to adjust;

Description

Technical Field

[0001] The utility model relates to the technical field of power systems, and particularly relates to a continuously adjustable overcurrent protection circuit. Background Art

[0002] When the power system is in operation, accidents often occur due to misoperation of overcurrent protection in the system, causing huge economic losses. The utility model proposes measures to be taken for misoperation of overcurrent protection and various situations, and also proposes the direction for improvement of overcurrent protection. China is in an important period of economic development, and the demand for electricity in all walks of life is increasing day by day. Therefore, preventing electricity consumption accidents has become an urgent problem to be solved. During the operation of the power system, various faults and abnormal operating states may occur. The most common and dangerous fault is various forms of short circuits. When a short circuit occurs, the short-circuit current flowing through the fault point is very large, which may damage the stability of the parallel operation of the system. Therefore, it is necessary to configure overcurrent protection in the system. However, in some cases, even if the action value and time of the overcurrent protection device adopted are reasonably matched, due to poor coordination with other protections in the system, it may cause misoperation and result in faults in the entire system. Therefore, with the increasing compactness of the power grid structure, whether the overcurrent protection can operate correctly is very important for the safe and stable operation of the power system.

[0003] An overcurrent protection circuit is an electronic device used to monitor and protect the load in a circuit from excessive current damage. When the current in the circuit exceeds the set threshold, the overcurrent protection circuit will automatically trigger a protection action. This protection device can effectively prevent circuit components and equipment from being damaged due to overload, improving the stability and reliability of the circuit.

[0004] Overcurrent protectors are widely used in various electrical appliances and electronic circuits, mainly playing the role of overcurrent protection in the circuit. Currently, the commonly used overcurrent protectors on the market are mainly fixed-ampere overcurrent devices, which have the disadvantage that the overcurrent protection value cannot be adjusted when the electrical appliance is changed. In addition, many overcurrent protection circuits use the resistance sampling method, and when there is a large current, it may cause the sampling resistance power to be too large and easily burn out the circuit. Content of the Utility Model

[0005] The embodiments of the present application are proposed to make up for the deficiencies of the prior art, and propose a continuously adjustable overcurrent protection circuit to solve the problems existing in the prior art.

[0006] In order to solve the above technical problems, the utility model provides the following technical solutions:

[0007] A continuously adjustable overcurrent protection circuit includes operational amplifier N1, operational amplifier N2 and voltage comparator N3. Pin 3 of the operational amplifier N1 is connected to resistor R2, and the other end of the resistor R2 is connected to the negative electrode of diode V4, the positive electrode of diode V3, the positive electrode of diode V2, capacitor C1, resistor R1 and capacitor C2. The negative electrode of diode V3 is connected to the +15V voltage, the positive electrode of diode V4 is connected to the -15V voltage, the negative electrode of diode V2 is connected to the negative electrode of diode V1, and the positive electrode of diode V1 is connected to the other end of resistor R1, the other end of capacitor C1 and the other end of capacitor C2. Pin 2 of the operational amplifier N1 is connected to resistor R3, and the other end of the resistor R3 is connected to resistor R4 and pin 6 of the operational amplifier N1. Pin 7 of the operational amplifier N1 is connected to capacitor C3 and the +15V voltage, the other end of capacitor C3 is connected to capacitor C4, and the other end of capacitor C4 is connected to the -15V voltage. The other end of resistor R4 is connected to pin 3 of the operational amplifier N1. Pin 2 of the operational amplifier N1 is connected to capacitor C5, resistor R5 and potentiometer RP1. The other end of capacitor C5 is connected to capacitor C6, resistor R6 and pin 6 of the operational amplifier N2. The other end of the potentiometer RP1 is connected to the other end of capacitor C6. Pin 4 of the operational amplifier N2 is connected to capacitor C11 and the -15V voltage. Pin 7 of the operational amplifier N2 is connected to capacitor C10 and the +15V voltage. The other end of resistor R6 is connected to capacitor C13 and pin 2 of the voltage comparator N3. Pin 3 of the voltage comparator N3 is connected to the control end of the potentiometer RP2 and capacitor C12. The other end of capacitor C12 is connected to one end of the potentiometer RP2. The other end of the potentiometer RP2 is connected to resistor R7. The other end of resistor R7 is connected to the +15V voltage. Pin 8 of the voltage comparator N3 is connected to capacitor C14. Pin 1 of the voltage comparator N3 is connected to capacitor C15, and the other end of capacitor C15 is connected to pin 4 of the voltage comparator N3.

[0008] As a further technical solution of the present invention: The model of the operational amplifier N1 is TL081CP.

[0009] As a further technical solution of the present invention: The model of the operational amplifier N2 is TL081CP.

[0010] As a further technical solution of the present invention: The model of the voltage comparator N3 is LM311P.

[0011] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0012] 1. By adopting the current protection circuit, the load can be well protected from being damaged, so that the power supply itself is not afraid of short circuit and overload, and there is no any adverse effect in the state of short circuit and overload, and it is allowed to remove the short circuit fault for a long time.

[0013] 2. When the current protection gear needs to be adjusted, the potentiometer can be adjusted conveniently and quickly. Description of the Drawings

[0014] Figure 1 It is the circuit diagram of a continuously adjustable overcurrent protection circuit. Specific Embodiments

[0015] Next, the technical solutions in the embodiments of the present invention will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0016] As Figure 1 shown, a continuously adjustable overcurrent protection circuit includes operational amplifier N1, operational amplifier N2 and voltage comparator N3. The pin 3 of the operational amplifier N1 is connected to the resistor R2, and the other end of the resistor R2 is connected to the negative electrode of the diode V4, the positive electrode of the diode V3, the positive electrode of the diode V2, the capacitor C1, the resistor R1 and the capacitor C2. The negative electrode of the diode V3 is connected to the +15V voltage, the positive electrode of the diode V4 is connected to the -15V voltage, the negative electrode of the diode V2 is connected to the negative electrode of the diode V1, and the positive electrode of the diode V1 is connected to the other end of the resistor R1, the other end of the capacitor C1 and the other end of the capacitor C2. The pin 2 of the operational amplifier N1 is connected to the resistor R3, and the other end of the resistor R3 is connected to the resistor R4 and the pin 6 of the operational amplifier N1. The pin 7 of the operational amplifier N1 is connected to the capacitor C3 and the +15V voltage, the other end of the capacitor C3 is connected to the capacitor C4, and the other end of the capacitor C4 is connected to the -15V voltage. The other end of the resistor R4 is connected to the pin 3 of the operational amplifier N1. The pin 2 of the operational amplifier N1 is connected to the capacitor C5, the resistor R5 and the potentiometer RP1. The other end of the capacitor C5 is connected to the capacitor C6, the resistor R6 and the pin 6 of the operational amplifier N2. The other end of the potentiometer RP1 is connected to the other end of the capacitor C6. The pin 4 of the operational amplifier N2 is connected to the capacitor C11 and the -15V voltage. The pin 7 of the operational amplifier N2 is connected to the capacitor C10 and the +15V voltage. The other end of the resistor R6 is connected to the capacitor C13 and the pin 2 of the voltage comparator N3. The pin 3 of the voltage comparator N3 is connected to the control end of the potentiometer RP2 and the capacitor C12. The other end of the capacitor C12 is connected to one end of the potentiometer RP2. The other end of the potentiometer RP2 is connected to the resistor R7. The other end of the resistor R7 is connected to the +15V voltage. The pin 8 of the voltage comparator N3 is connected to the capacitor C14. The pin 1 of the voltage comparator N3 is connected to the capacitor C15. The other end of the capacitor C15 is connected to the pin 4 of the voltage comparator N3.

[0017] The working principle is as follows:

[0018] A current signal is obtained through a range potentiometer (sampling resistor RP1) in the sampling circuit. After being amplified by an operational amplifier, it is sent to the positive terminal of a comparator (LM311P) to be compared with the threshold current provided in the circuit. When the operating current of the system exceeds the set value, the current in the operational amplifier is greater than the threshold current of the comparator, and the comparator outputs a high level. The adjustment range of the output current can be jointly determined by the potentiometer and the threshold current of the comparator. In specific use, the current adjustment parameters can be set more flexibly according to different situations. The threshold of the protection current is changed through the potentiometer to achieve the purpose of current protection.

[0019] Among them, the operational amplifier TL081CP: A commonly used high-performance JFET input, bipolar output operational amplifier, with low input bias current and high slew rate. These operational amplifiers have low noise and low distortion, and are suitable for a wide range of audio and signal processing applications. The high input impedance makes it an ideal choice for applications where the circuit load must be minimized. The TL081CP device provides offset adjustment and external compensation options. Low input bias and compensation current.

[0020] The voltage comparator LM311P: The LM311P is a differential input voltage comparator, with a wide operating voltage range and a response time of 200 ns. The inputs of these devices can be isolated from the system ground, and the free outputs can drive power supply rails or ground loads. The voltage comparator includes not only traditional single, dual, and quad comparator packages, but also serial comparators and overvoltage and undervoltage monitors. Although comparators and operational amplifiers are superficially similar devices, their operations in practical applications are very different. Operational amplifiers are suitable for linear operation, with appropriate feedback, while comparators are customized for fast switching and usually operate in an open-loop mode. Specialized voltage comparators have significantly shorter propagation delays and can have faster response times under saturation conditions. Most comparators are also more tolerant of high differential input voltages, and many comparators have open collector outputs, allowing them to be operated in parallel with other devices.

[0021] When an operational amplifier constitutes a comparator circuit, it is mostly used in an open-loop or positive feedback working state, that is, working in the non-linear region. When the comparator works in positive feedback, the circuit has a hysteresis characteristic. At this time, the comparator has two threshold voltages, and the difference between the two constitutes a hysteresis range. Usually, this comparator is called a Schmitt trigger or a hysteresis comparator. At this time, even if noise is superimposed on the input signal, as long as the noise level is within the hysteresis range, the output will not have a misoperation of multiple triggers.

[0022] A continuously adjustable overcurrent protection circuit device proposed by the present utility model can solve the application scenarios where the overcurrent protection circuit needs to adjust the current protection threshold.

[0023] For those skilled in the art, it is obvious that the present utility model is not limited to the details of the above-mentioned exemplary embodiments, and the present utility model can be implemented in other specific forms without departing from the spirit or basic characteristics of the present utility model. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present utility model is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present utility model.

[0024] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment have been appropriately combined to form other embodiments that are easily understood by those skilled in the art.

Claims

1. A continuously adjustable overcurrent protection circuit, comprising an operational amplifier N1, an operational amplifier N2 and a voltage comparator N3, characterized in that: Pin 3 of the operational amplifier N1 is connected to resistor R2. The other end of resistor R2 is connected to the cathode of diode V4, the anode of diode V3, the anode of diode V2, capacitor C1, resistor R1, and capacitor C2. The cathode of diode V3 is connected to the +15V voltage. The anode of diode V4 is connected to the -15V voltage. The cathode of diode V2 is connected to the cathode of diode V1. The anode of diode V1 is connected to the other end of resistor R1, the other end of capacitor C1, and the other end of capacitor C2. Pin 2 of the operational amplifier N1 is connected to resistor R3. The other end of resistor R3 is connected to resistor R4 and pin 6 of the operational amplifier N1. Pin 7 of the operational amplifier N1 is connected to capacitor C3 and the +15V voltage. The other end of capacitor C3 is connected to capacitor C4. The other end of capacitor C4 is connected to the -15V voltage. The other end of resistor R4 is connected to pin 3 of the operational amplifier N1. Pin 2 of the operational amplifier N1 is connected to capacitor C5, resistor R5, and potentiometer RP1. The other end of capacitor C5 is connected to capacitor C6, resistor R6, and pin 6 of the operational amplifier N2. The other end of potentiometer RP1 is connected to the other end of capacitor C6. Pin 4 of the operational amplifier N2 is connected to capacitor C11 and the -15V voltage. Pin 7 of the operational amplifier N2 is connected to capacitor C10 and the +15V voltage. The other end of resistor R6 is connected to capacitor C13 and pin 2 of the voltage comparator N3. Pin 3 of the voltage comparator N3 is connected to the control terminal of potentiometer RP2 and capacitor C12. The other end of capacitor C12 is connected to one end of potentiometer RP2. The other end of potentiometer RP2 is connected to resistor R7. The other end of resistor R7 is connected to the +15V voltage. Pin 8 of the voltage comparator N3 is connected to capacitor C14. Pin 1 of the voltage comparator N3 is connected to capacitor C15. The other end of capacitor C15 is connected to pin 4 of the voltage comparator N3.

2. The continuously adjustable overcurrent protection circuit according to claim 1, wherein The model of the operational amplifier N1 is TL081CP.

3. The continuously adjustable overcurrent protection circuit according to claim 1, characterized in that, The model of the operational amplifier N2 is TL081CP.

4. A continuously adjustable overcurrent protection circuit according to claim 1, characterized in that, The model of the voltage comparator N3 is LM311P.

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