Optocoupler isolation control circuit

Abstract

An optocoupler isolation control circuit comprises a signal input module, an optocoupler isolation module, a signal driving module, a power switch module and an output control module, and the signal input module is used for receiving an external control signal; the optical coupler isolation module is used for realizing electrical isolation between the signal input module and the output control module and transmitting the external control signal to the signal driving module; the signal driving module is used for driving the power switch module to be switched on or switched off; the power switch module is used for controlling the on state of an external load according to an output signal of the signal driving module; and the output control module is used for outputting working voltage of an external load. According to the embodiment of the utility model, electrical isolation is realized through the optical coupler isolation module, and the driving capability is improved while stable transmission of signals is ensured by combining cooperative control of multi-stage driving and the power switch module.

Description

TECHNICAL FIELD

[0001] The utility model relates to control circuit technical field, concretely relates to a photoelectric coupler isolation control circuit. BACKGROUND

[0002] In electronic control system, MOS tube is widely used in various load control circuits because of its fast switching speed, low power consumption, easy to drive and other advantages, because the control mode structure of MOS tube is simple, the design cost is low, is widely used in household appliance control, power management, automation equipment and so on, especially suitable for the system with the control end and load power common, has become the commonly used technical scheme in the industry.

[0003] In the prior art, reference Figure 1 The control signal is directly connected to the gate of the MOS tube after passing through the series current limiting resistor, the MOS tube is turned on when the control signal is high, and the conduction control of the load is realized, and the MOS tube is cut off when the control signal is low, and the load is disconnected.

[0004] The prior art has the following problems:

[0005] On the one hand, the control signal directly drives the gate of the MOS tube without isolation amplification, and the driving capacity is weak, which is difficult to meet the needs of high-current load or high-speed switching scene, and is prone to cause incomplete or delayed conduction of the MOS tube;

[0006] On the other hand, the circuit structure of the prior art is sensitive to power supply voltage fluctuation, and when there is ripple in the power supply or the voltage is unstable, it is more prone to mis-conduction or mis-disconnection, which affects the overall stability of the circuit. INVENTION CONTENTS

[0007] In order to solve the above problems existing in the prior art, the utility model aims at providing a photoelectric coupler isolation control circuit and a charging pile control system, which solves the problem that the prior art cannot meet the needs of high-current load or high-speed switching scene, and enhances the overall anti-interference of the circuit.

[0008] The technical scheme adopted by the utility model is:

[0009] A photoelectric coupler isolation control circuit, comprising:

[0010] A signal input module, a photoelectric coupler isolation module, a signal driving module, a power switch module and an output control module, the output end of the signal input module is connected with the signal transmitting end of the photoelectric coupler isolation module, the signal receiving end of the photoelectric coupler isolation module is connected with the signal driving module, the power switch module, the output control module and the ground end, the output end of the output control module is connected with the input end of the signal driving module and the power switch module respectively, wherein:

[0011] The signal input module is configured to receive an external control signal.

[0012] The optocoupler isolation module is configured to achieve electrical isolation between the signal input module and the output control module, and transmit the external control signal to the signal drive module.

[0013] The signal drive module is configured to drive the power switch module to turn on or turn off.

[0014] The power switch module is configured to control the on-off state of an external load according to the output signal of the signal drive module.

[0015] The output control module is configured to output the operating voltage of the external load.

[0016] Further, the optocoupler isolation module includes an optocoupler O1, which includes a signal transmitting positive terminal, a signal transmitting negative terminal, a signal receiving positive terminal, and a signal receiving negative terminal. The signal transmitting positive terminal and the signal transmitting negative terminal are connected to the signal input module. The signal receiving positive terminal is connected to the signal drive module, the power switch module, and the output control module. The signal receiving negative terminal is connected to the signal drive module, the power switch module, the output control module, and a ground terminal.

[0017] Further, the signal input module includes a resistor R1, a resistor R2, a resistor R5, and a light-emitting diode LED1. One end of the resistor R1 is connected to an external signal transmitting terminal. The other end of the resistor R1 is connected to the anode of the light-emitting diode LED1, one end of the resistor R2, and the signal transmitting positive terminal. The cathode of the light-emitting diode LED1 is grounded through the resistor R5. The other end of the resistor R2 is connected to the signal transmitting negative terminal.

[0018] Further, the optocoupler isolation module further includes a capacitor C1. One end of the capacitor C1 is connected to one end of the resistor R2 and the signal transmitting positive terminal. The other end of the capacitor C1 is connected to the other end of the resistor R2 and the signal transmitting negative terminal.

[0019] Further, the signal drive module includes a switching tube Q1. The base of the switching tube Q1 is connected to the signal receiving positive terminal and the output control module. The emitter of the switching tube Q1 is connected to the output control module. The collector of the switching tube Q1 is connected to the control terminal of the power switch module and a ground terminal. The switching tube Q1 is a triode.

[0020] Further, the signal drive module further includes a resistor R3 and a capacitor C2. The signal receiving positive terminal is connected to the emitter of the switching tube Q1 through the resistor R3 and the capacitor C2, respectively.

[0021] Further, the power switch module comprises a switch tube Q2, a gate of the switch tube Q2 is connected with an emitter of the switch tube Q1 and a ground terminal, a drain of the switch tube Q2 is connected with the output control module, a source of the switch tube Q2 is grounded, and the switch tube Q2 is a MOS tube.

[0022] Further, the power switch module further comprises a resistor R4 and a diode D1, the gate of the switch tube Q2 is grounded through the resistor R4, an anode of the diode D1 is connected with the output control module and the drain of the switch tube Q2, and a cathode of the diode D1 is connected with the source of the switch tube Q2 and the ground terminal.

[0023] Further, the power switch module further comprises a resistor R6 and a capacitor C3, one end of the resistor R6 is connected with the cathode of the diode D1, the source of the switch tube Q2, the collector of the switch tube Q1 and the ground terminal, and the other end of the resistor R6 is connected with the output control module, the drain of the switch tube Q2 and the emitter of the switch tube Q1 through the capacitor C3.

[0024] Further, the output control module comprises a fuse F1, one end of the fuse F1 is connected with the signal driving module and the power switch module, and the other end of the fuse F1 is connected with an external load.

[0025] As can be seen from the above, the embodiment of the utility model realizes electrical isolation through the optical coupling isolation module, and the driving capacity is improved while ensuring stable signal transmission through the synergic control of the multi-stage driving and power switch modules, and the voltage fluctuation influence is reduced through the filtering element, so that the utility model has the advantages of enhancing the driving capacity, improving the anti-interference and ensuring the stable power supply. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical scheme in the embodiment of the utility model or the prior art, the drawings needed to be used in the embodiment or the prior art description will be briefly introduced below, and obviously, the drawings in the following description are only some embodiments of the utility model, and other drawings can be obtained by those skilled in the art without creative labor.

[0027] Figure 1 It is a circuit principle schematic diagram of the prior art;

[0028] Figure 2 It is a circuit principle block diagram of the utility model;

[0029] Figure 3 It is a circuit principle schematic diagram of the optical coupling isolation control circuit of the utility model.

[0030] Reference signs:

[0031] 100, signal input module; 200, opto-isolator module; 300, signal drive module; 400, power switch module; 500, output control module. DETAILED DESCRIPTION

[0032] The utility model will be described further in detail below in combination with the drawings.

[0033] The specific embodiment is only an explanation of the utility model, and it is not a limitation of the utility model. Those skilled in the art can make modifications to the embodiment without creative contribution after reading the specification, but as long as it is within the scope of the claims of the utility model, it is protected by the patent law.

[0034] To make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be described clearly and completely below in combination with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all the embodiments. The components of the embodiments of the utility model described and shown in the drawings can be arranged and designed in various different configurations.

[0035] Therefore, the detailed description of the embodiments of the utility model provided in the drawings below is not intended to limit the scope of the claimed utility model, but only represents selected embodiments of the utility model. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the utility model.

[0036] In the prior art, the electronic control system generally uses MOS tube as the core element of load control, and its application scenarios cover home appliance control, power management and automation equipment field. When the control end and the load power are common, the traditional scheme directly connects the MOS tube gate through the current-limiting resistor to realize the conduction control. However, in the scenes of industrial automation equipment, high-precision instruments and meters, etc., such scheme is easy to cause switch hysteresis due to insufficient driving capacity, and power fluctuation may cause misoperation, affecting the system reliability.

[0037] Reference Figure 1In the existing control circuit structure, a control signal is connected to the gate of a MOS tube Q1 through a resistor R1, and a simple pull-down or current limiting design is realized through R2, R3 and other elements. When the input is high, Q1 is turned on to realize closed control of the load; when the input is low, Q1 is turned off, and the load is disconnected. Such a circuit is simple in structure, easy to implement, and widely used in low-power control occasions. However, this structure has obvious limitations: first, the control signal directly acts on the MOS gate without amplification or isolation, resulting in limited driving ability and difficulty in dealing with high-voltage or large-current loads; second, the power voltage fluctuation has a significant impact on the gate voltage, which may cause Q1 to enter a critical conduction state, thereby causing control malfunction; third, the control side and the load side are not electrically isolated, and external interference signals are easily transmitted to the control side, weakening the anti-interference ability of the entire system. Therefore, the prior art urgently needs a load control circuit scheme with reasonable structure, strong driving ability and high anti-interference ability to improve the control reliability and system safety in complex application environments.

[0038] To solve the above problems, the applicant found that the lack of driving ability is due to the lack of amplification in the signal path, and the power sensitivity problem reflects the lack of isolation measures. Through analysis, it is found that introducing an isolation device in the signal transmission link can block interference conduction, and increasing the driving stage can improve the current output ability of the gate control signal. Further thinking found that if the isolation function and driving amplification are combined and an independent power supply path is constructed, the driving ability and anti-interference problem can be solved at the same time.

[0039] First embodiment:

[0040] Referring to Figure 2 The utility model embodiment provides a kind of optical coupling isolation control circuit, comprising:

[0041] Signal input module 100, optical coupling isolation module 200, signal driving module 300, power switch module 400 and output control module 500, the output end of the signal input module 100 is connected the signal transmitting end of the optical coupling isolation module 200, the signal receiving end of the optical coupling isolation module 200 is connected the signal driving module 300, the power switch module 400, the output control module 500 and ground terminal, the output end of the output control module 500 is connected respectively the input end of the signal driving module 300 and the power switch module 400, wherein:

[0042] The signal input module 100 is used to receive external control signal;

[0043] The optical coupling isolation module 200 is used to realize the electrical isolation between the signal input module 100 and the output control module 500, and transmit the external control signal to the signal driving module 300;

[0044] The signal driving module 300 is used to drive the conduction or turn-off of the power switch module 400;

[0045] The power switch module 400 is used to control the on-off state of the external load according to the output signal of the signal driving module 300;

[0046] The output control module 500 is used to output the working voltage of the external load.

[0047] Among them, the signal input module 100 refers to the interface circuit receiving external digital or analog control signal, which can be realized by combining resistance voltage division network and light emitting diode, and its function is to convert external signal into light signal emission current. The optocoupler isolation module 200 refers to the device for realizing electrical isolation, which can be realized by using the packaging structure containing light emitting device and photosensitive device, and its core function is to block the direct electrical connection between the control end and the load end. The signal driving module 300 refers to the circuit unit for amplifying the isolated signal, which can be realized by using transistor amplification circuit, and is used to improve the control signal strength of the driving power switch module 400. The power switch module 400 refers to the semiconductor device for controlling the on-off of the load current, which can be realized by using MOS tube, and its function is to quickly switch the load circuit state according to the driving signal. The output control module 500 refers to the power supply unit for providing stable working voltage for the load, which can be realized by combining fuse and voltage stabilizing element, and is used to isolate the load power supply and control circuit.

[0048] Specifically, the external control signal is converted into driving current by the signal input module 100, and the light emitting device in the optocoupler isolation module 200 is activated to generate light signal. The photosensitive device is turned on after receiving the light signal, and the signal is transmitted to the signal driving module 300 for current amplification. The amplified signal drives the gate of the power switch module 400, so that it quickly switches between saturated conduction and complete cut-off state. The output control module 500 provides an independent power supply path for the load when the power switch is on, and cuts off the circuit through the fuse protection when the abnormal current occurs. The optocoupler isolation module 200 blocks the ground loop interference, the signal driving module 300 enhances the gate drive current, and the output control module 500 stabilizes the power supply at the load end. The three work together to realize reliable control.

[0049] Compared with the prior art, in the traditional scheme, the control signal directly drives the gate of the MOS tube, and no isolation and amplification link is set, so that the driving current is limited by the output capacity of the signal source. In this scheme, the interference path is cut off by the optocoupler isolation, the gate drive strength is improved by the signal driving module 300, so that the power switch module 400 can complete the state switching within milliseconds. At the same time, the output control module 500 builds an independent power supply loop, which avoids the reverse influence of load power supply fluctuation on the control circuit.

[0050] By the technical solution, the driving response speed of the power switch device is effectively improved, and in the motor start-stop and relay control scenarios, the switching loss can be reduced by about 40%. The optical coupling isolation design improves the ground potential difference tolerance of the control end and the load end to the kilovolt level, and is suitable for strong interference environments such as frequency converters and inverter power supplies. The independent power supply mechanism of the output control module 500 reduces the influence of the load end voltage fluctuation on the control signal to less than 1 / 5 of the original level, significantly enhancing the system anti-interference ability.

[0051] Second embodiment:

[0052] Referring to Figure 3 Further, the optical coupling isolation module 200 includes an optical coupling O1, the optical coupling O1 includes a signal transmitting positive electrode, a signal transmitting negative electrode, a signal receiving positive electrode and a signal receiving negative electrode, the signal transmitting positive electrode and the signal transmitting negative electrode are connected to the signal input module 100; the signal receiving positive electrode is connected to the signal driving module 300, the power switch module 400 and the output control module 500, and the signal receiving negative electrode is connected to the signal driving module 300, the power switch module 400, the output control module 500 and the ground end.

[0053] Wherein, the optical coupling O1 refers to a device for realizing electrical isolation by using photoelectric conversion principle, and specifically can be realized by using PC817 type optical coupling, the signal transmitting positive electrode and the signal transmitting negative electrode are used for receiving input signal and driving internal light emitting diode to emit light, and the signal receiving positive electrode and the signal receiving negative electrode convert optical signal into electrical signal output through photoelectric transistor. The signal transmitting positive electrode refers to the positive electrode pin of the light emitting diode at the input end of the optical coupling, which can be connected to the resistor R1 by welding, and is used for receiving input signal current to form a driving loop. The signal receiving positive electrode refers to the collector pin of the photoelectric transistor at the output end of the optical coupling, which can be connected to the base of the switch tube Q1 by wire, and is used for transmitting the isolated control signal to the subsequent circuit.

[0054] Specifically, when the external control signal is transmitted to the transmitting positive electrode of the optical coupling O1 through the signal input module 100, the internal light emitting diode is turned on to emit light, and the photoelectric transistor is triggered to be turned on. At this time, the signal receiving positive electrode and the output control module 500 form a current path, and the working voltage provides energy for the subsequent driving circuit through the path. At the same time, the connection of the signal receiving negative electrode and the ground end of each module forms a stable reference potential, which ensures that the signal transmission process will not be affected by the ground potential fluctuation. The physical isolation characteristic of the optical coupling O1 makes there is no electrical connection between the input side and the output side, thereby effectively blocking the conduction path of the interference signal.

[0055] Compared with the prior art, the prior art lacks an electrical isolation link for directly driving the MOS tube gate by the control signal, and misoperation is prone to occur when common mode interference exists between the input end and the load end. The isolation barrier formed by the optical coupling O1 can block the direct current component and low frequency interference between the input and output sides, while ensuring the complete transmission of the control signal. The photoelectric coupling mode has higher response speed and simpler circuit structure than the magnetic isolation or capacitor isolation scheme.

[0056] Through the above technical scheme, the interference coupling problem between the control circuit and the power circuit is effectively solved, and the working stability of the system in a complex electromagnetic environment is improved. The introduction of the optical coupling isolation module 200 makes the control signal transmission not affected by the ground potential difference, avoids the mis-triggering of the MOS tube caused by power fluctuations, and at the same time enhances the control accuracy of the driving circuit to the power switch module 400.

[0057] Reference Figure 3 Further, the signal input module 100 includes resistors R1, R2, R5, and a light-emitting diode LED1. One end of the resistor R1 is connected to an external signal sending end. The other end of the resistor R1 is connected to the anode of the light-emitting diode LED1, one end of the resistor R2, and the positive electrode of the signal emitting end. The cathode of the light-emitting diode LED1 is grounded through the resistor R5. The other end of the resistor R2 is connected to the negative electrode of the signal emitting end.

[0058] The resistor R1 is a current-limiting element for limiting input current, which can be implemented by a metal film resistor or a carbon film resistor, for example, with a resistance range of 1kΩ to 10kΩ, to prevent damage to the optical coupling device caused by overload of the external control signal.

[0059] The light-emitting diode LED1 is a light-emitting device for state indication, which can be implemented by a surface mount type or a straight insertion type LED, for example, with a working current controlled within a range of 5mA to 20mA, and the cathode potential difference is adjusted by the resistor R5 to control the conduction brightness.

[0060] The resistor R2 is a matching element for signal voltage division, which can be implemented by a thin film resistor with an accuracy of ±5%, for example, with a resistance range of 2kΩ to 15kΩ, to adjust the driving voltage of the optical coupling signal emitting end together with the resistor R1.

[0061] The resistor R5 is a pull-down resistor, which can be implemented by a low temperature coefficient resistor, for example, with a resistance range of 1kΩ to 5kΩ, to ensure that the light-emitting diode LED1 is reliably cut off when there is no signal input, avoiding mis-triggering.

[0062] Specifically, when the external control signal is input through the signal sending end, the current is divided into two paths after being limited by the resistor R1: one path flows to the light-emitting diode LED1 to make it emit light to indicate the input state of the signal, and the other path is transmitted to the positive electrode of the signal emitting end of the optocoupler through the resistor R2. The cathode current of the light-emitting diode LED1 forms a closed loop through the resistor R5. At this time, the negative electrode of the signal emitting end of the optocoupler forms a potential difference with the input signal through the resistor R2, thereby driving the internal light-emitting device of the optocoupler to work. The matching of the resistance values of the resistor R1 and the resistor R2 can ensure that the driving current of the optocoupler is in the safe working interval, and the existence of the resistor R5 avoids the misoperation caused by the floating of the input signal.

[0063] Compared with the prior art, in the prior art, the control signal is directly connected to the gate of the MOS tube, and lacks input state indication and signal conditioning functions. The present scheme realizes signal transmission and visual monitoring of the input state at the same time through the resistor voltage dividing network and the light-emitting diode, and the determined potential path formed by the resistor R5 significantly improves the anti-interference ability and avoids the risk of mis-triggering caused by the floating of the signal input end.

[0064] Reference Figure 3 Further, the optocoupler isolation module 200 further includes a capacitor C1, one end of the capacitor C1 is connected to one end of the resistor R2 and the positive electrode of the signal emitting end, and the other end of the capacitor C1 is connected to the other end of the resistor R2 and the negative electrode of the signal emitting end.

[0065] Among them, the capacitor C1 refers to a filter capacitor connected in parallel between the two poles of the signal emitting end, which can be realized by a ceramic capacitor with a capacitance of 0.1 microfarad, which is used to suppress high-frequency interference signals at the input end of the optocoupler, and reduce signal noise by absorbing transient voltage fluctuations. The resistor R2 refers to a current-limiting element connected in series between the signal input module 100 and the emitting end of the optocoupler, which can be realized by a carbon film resistor with a resistance of 1 kilo-ohm, which is used to adjust the input current size to avoid overloading of the internal light-emitting diode of the optocoupler.

[0066] Specifically, when the external control signal is transmitted to the optocoupler isolation module 200, the resistor R2 and the capacitor C1 form an RC filter circuit. When the signal input module 100 transmits the external control signal to the positive electrode of the emitting end of the optocoupler, the resistor R2 limits the input current, and the capacitor C1 bypass filters the high-frequency noise of the signal emitting end. For example, when there are high-frequency ripples or voltage spikes in the external control signal, the capacitor C1 absorbs transient energy through charging and discharging, making the driving current of the optocoupler light-emitting diode smooth, thereby improving the stability of the internal photoelectric conversion process of the optocoupler. Through this filtering structure, the electrical signal output by the receiving end of the optocoupler is synchronized with the logic state of the input signal, avoiding the misoperation of the driving module caused by the distortion of the input signal.

[0067] Compared with the prior art, the input signal is not filtered in the prior art when the control signal directly drives the gate of the MOS tube, which leads to false triggering caused by power fluctuation or external interference. The RC filter structure added to the input end of the optocoupler can effectively suppress the influence of high-frequency interference on the internal photoelectric conversion of the optocoupler and reduce the risk of noise superposition in the signal transmission process. For example, under the condition of large power ripple, the capacitor C1 reduces the voltage fluctuation amplitude of the signal transmitting end through high-frequency bypass action, thereby ensuring the logic accuracy of the optocoupler output signal.

[0068] With reference to Figure 3 Further, the signal driving module 300 includes a switching tube Q1, a base of the switching tube Q1 is connected to the positive pole of the signal receiving end and the output control module 500, an emitter of the switching tube Q1 is connected to the output control module 500, a collector of the switching tube Q1 is connected to the control end of the power switch module 400 and the ground end, and the switching tube Q1 is a triode.

[0069] The switching tube Q1 is a semiconductor device for controlling the conduction or turn-off of the power switch module 400, and can be implemented by a triode, the base of which receives the driving signal transmitted by the optocoupler isolation module 200 and enhances the control ability of the power switch module 400 through current amplification.

[0070] The base refers to the input end of the triode, which can be implemented by connecting the positive pole of the signal receiving end of the optocoupler isolation module 200, for receiving the isolated control signal and ensuring the electrical isolation of signal transmission.

[0071] The emitter refers to one of the output ends of the triode, which can be implemented by connecting the voltage node of the output control module 500, for providing driving current to the power switch module 400.

[0072] The collector refers to one of the output ends of the triode, which can be implemented by connecting the control end and the ground end of the power switch module 400, for forming a current loop and controlling the conduction state of the power switch module 400.

[0073] The triode refers to a bipolar transistor with current amplification function, which can be implemented by an NPN or PNP triode, the conduction degree between the collector and the emitter is controlled by the base current, thereby improving the driving ability.

[0074] Specifically, when the opto-isolation module 200 transmits an external control signal to the signal receiving end positive electrode, the base of the switch tube Q1 receives the signal and adjusts the conduction state according to the voltage change. When the external control signal is high, the transistor is turned on, a low impedance path is formed between the collector and the emitter, and the control end of the power switch module 400 is grounded to turn it on; when the external control signal is low, the transistor is turned off, and the control end of the power switch module 400 is disconnected from the ground state to turn it off. Thus, the current amplification of the transistor enhances the driving ability and ensures the fast response of the power switch module 400.

[0075] Compared with the prior art, in the prior art, the control signal directly drives the gate of the MOS tube without isolation and amplification, resulting in limited driving ability and being easily affected by power fluctuations. In the present scheme, a transistor is introduced as a driving stage to improve the strength of the driving signal by using its current amplification characteristics, and the electrical isolation between the control end and the load end is realized by the opto-isolation module 200, reducing the interference of power fluctuations on the control signal.

[0076] Reference Figure 3 Further, the signal driving module 300 further comprises a resistor R3 and a capacitor C2, and the signal receiving end positive electrode is connected to the emitter of the switch tube Q1 through the resistor R3 and the capacitor C2, respectively.

[0077] Among them, the resistor R3 refers to a current-limiting element arranged between the opto-isolation signal receiving end positive electrode and the transistor emitter, which can be realized by a carbon film resistor or a metal film resistor, for limiting the current of the opto-isolation output end and forming a voltage dividing network. The capacitor C2 refers to a filtering element connected in parallel between the opto-isolation signal receiving end positive electrode and the transistor emitter, which can be realized by a ceramic capacitor or an electrolytic capacitor, for absorbing high-frequency interference signals and delaying the rising edge of the driving signal.

[0078] Specifically, when the opto-isolation receiving end outputs a high level, the resistor R3 and the transistor base resistor form a voltage dividing network, and the driving current of the transistor base can be accurately controlled by adjusting the resistance value. The capacitor C2 is connected in parallel in the driving signal path, and when the external control signal changes rapidly, the capacitor can eliminate the peak interference caused by signal jitter through the charging and discharging process. For example, when there is a ripple in the power supply voltage, the capacitor C2 can filter out high-frequency noise components, ensuring that the switch tube Q1 only operates at a stable driving level, thereby avoiding false triggering caused by power fluctuations.

[0079] Compared with the prior art, the traditional scheme directly connects the control signal to the gate of the MOS tube, lacking current limiting and filtering links, and is prone to false operation in the environment of power grid fluctuations or high-frequency interference. The present scheme sets up a resistor and capacitor combination network, which not only realizes accurate control of the driving current, but also effectively suppresses the influence of electromagnetic interference on the driving signal through RC filtering.

[0080] Referring to Figure 3 Further, the power switch module 400 further comprises a switch tube Q2, a gate of the switch tube Q2 is connected to an emitter of the switch tube Q1 and a ground terminal, a drain of the switch tube Q2 is connected to the output control module 500, a source of the switch tube Q2 is grounded, and the switch tube Q2 is a MOS tube.

[0081] wherein the resistor R4 refers to a pull-down resistor connected between the gate of the MOS tube and the ground, and can be implemented by a fixed-value patch resistor or a carbon film resistor, for ensuring that the MOS tube is reliably turned off when there is no driving signal, and avoiding mis-conduction caused by stray current or induced voltage. The diode D1 refers to a freewheeling diode connected in parallel between the drain and the source of the MOS tube, and can be implemented by a fast-recovery diode or a Schottky diode, for providing a current discharge path when the load is disconnected, and suppressing the influence of the reverse electromotive force on the circuit.

[0082] Specifically, when the driving signal is transmitted to the gate of the MOS tube Q2 through the switch tube Q1, the conduction state of the MOS tube Q2 is determined by the voltage level of the driving signal. The resistor R4 as a pull-down resistor can quickly pull down the gate potential to the ground level after the driving signal disappears, avoiding the MOS tube from being maintained in conduction due to residual charge. The diode D1 forms a freewheeling circuit when the load current suddenly changes, preventing the MOS tube from being broken down by the reverse voltage between the drain and the source due to inductive load. For example, when the external load is an inductive load, at the moment when the MOS tube is turned off, the diode D1 can guide the reverse electromotive force to the ground, protecting the safety of the power switch module 400.

[0083] Compared with the prior art, the prior art directly drives the MOS tube through the control signal, and the pull-down resistor is not provided, so that the gate potential cannot be quickly reset to zero, and misoperation is prone to occur; meanwhile, the freewheeling diode is not configured, and the reverse voltage impact cannot be effectively eliminated. The present scheme, through the synergistic effect of the resistor R4 and the diode D1, not only enhances the reliability of the MOS tube turn-off, but also improves the anti-interference ability of the circuit under dynamic working conditions.

[0084] Referring to Figure 3 Further, the power switch module 400 further comprises a resistor R4 and a diode D1, the gate of the switch tube Q2 is grounded through the resistor R4, the anode of the diode D1 is connected to the output control module 500 and the drain of the switch tube Q2, and the cathode of the diode D1 is connected to the source of the switch tube Q2 and the ground terminal.

[0085] Wherein, the resistor R4 refers to the discharge resistor connected between the switch tube gate and the ground, which can be realized by a 1kΩ chip resistor, for quickly releasing the gate charge when the switch tube is off, avoiding the residual charge leading to mis-conduction. The diode D1 refers to the freewheeling diode connected in parallel between the switch tube drain and source, which can be realized by a fast recovery diode FR107, for providing a current freewheeling path when the inductive load is disconnected, suppressing the impact of reverse electromotive force on the switch tube.

[0086] Specifically, when the external control signal changes, the optocoupler isolation module 200 transmits the signal to the signal driving module 300, driving the on or off state of the switch tube Q1. In the power switch module 400, the gate of the switch tube Q2 is grounded through the resistor R4 to form a discharge circuit, so that the gate voltage can quickly drop to the cutoff threshold. The diode D1 is connected across the drain and source of the switch tube Q2, and when the switch tube is off, the reverse electromotive force generated by the external load can form a current discharge path through the diode, avoiding damage to the switch tube by high voltage spikes.

[0087] Compared with the prior art, in the prior art, the MOS tube gate is directly connected with the control signal, which lacks a discharge resistor leading to off-delay, and lacks a freewheeling diode leading to the inability to effectively eliminate the reverse electromotive force. The present scheme can make the switch tube off speed increase by about 40% by setting a discharge resistor at the gate, and at the same time, the freewheeling diode can limit the reverse electromotive force peak value within a safe range, avoiding the switch tube from being broken down.

[0088] Reference Figure 3 Further, the power switch module 400 further includes a resistor R6 and a capacitor C3, one end of the resistor R6 is connected to the cathode of the diode D1, the source of the switch tube Q2, the collector of the switch tube Q1 and the ground terminal, the other end of the resistor R6 is connected to the output control module 500, the drain of the switch tube Q2 and the emitter of the switch tube Q1 through the capacitor C3.

[0089] Wherein, the resistor R6 refers to the current limiting element connected in series in the power switch module 400, which can be realized by a metal film resistor or a carbon film resistor, for limiting the current amplitude in the capacitor charging and discharging circuit. The capacitor C3 refers to the filter element connected in parallel in the power switch module 400, which can be realized by a ceramic capacitor or an electrolytic capacitor, for absorbing high frequency noise and maintaining the stability of the output node potential.

[0090] Specifically, the RC network formed by the resistor R6 and the capacitor C3 in series is connected across the drain and source of the power switch Q2. When the switch Q2 is turned on or off, the network can slow down the rate of change of the voltage between the drain and source, avoiding electromagnetic interference caused by sudden voltage changes. At the same time, the capacitor C3 can provide a low-impedance path for transient current during switching, thereby reducing switching loss. The presence of the resistor R6 can prevent the capacitor C3 from generating excessive inrush current during charging and discharging, protecting related components from damage.

[0091] In some embodiments, the resistance of the resistor R6 can range from 1kΩ to 10kΩ, and the capacitance of the capacitor C3 can range from 10nF to 100nF. The specific values can be adjusted according to the load current and switching frequency. In other embodiments, the resistor R6 and the capacitor C3 can be directly soldered near the pins of the power switch Q2 in a surface mount package form to shorten the current path.

[0092] Reference Figure 3 Further, the output control module 500 includes a fuse F1 connected between the signal drive module 300 and the power switch module 400, and connected to an external load at the other end.

[0093] The fuse F1 is a kind of overcurrent protection element, which can be implemented by a thermal fuse or a current-sensitive fuse, such as a glass tube fuse or a surface mount fuse. The fuse F1 is connected in series between the output control module 500 and the external load. When an overcurrent or short circuit occurs in the circuit, the fuse F1 cuts off the current path by melting, preventing the load or circuit components from being damaged by overcurrent.

[0094] Specifically, the output control module 500 transmits the operating voltage to the external load through the fuse F1, and the fuse F1 is connected to the drain of the power switch module 400 and the emitter of the signal drive module 300. When the power switch module 400 is turned on, the current path of the external load passes through the fuse F1. If a short circuit or abnormal current occurs on the load side, the fuse F1 melts based on the preset rated current value, disconnecting the electrical connection between the signal drive module 300, the power switch module 400, and the external load. This process does not require external detection circuits and directly achieves rapid protection through the physical properties of the fuse F1.

[0095] Compared with the prior art, in which the control signal directly drives the MOS tube without overcurrent protection device, the MOS tube or load is easily burned when the load is short-circuited or the current is abnormal. The present scheme adds a fuse F1 in the output control module 500 to form an overcurrent protection barrier between the power switch module 400 and the external load. When the abnormal current exceeds the threshold value, the circuit is automatically cut off, avoiding component damage.

[0096] The above merely provides an example of the present application, and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. An opto-coupler isolation control circuit, comprising: The application relates to a signal input module (100), an optical coupling isolation module (200), a signal driving module (300), a power switch module (400) and an output control module (500), wherein the output end of the signal input module (100) is connected with the signal transmitting end of the optical coupling isolation module (200), the signal receiving end of the optical coupling isolation module (200) is connected with the signal driving module (300), the power switch module (400), the output control module (500) and a grounding end, and the output end of the output control module (500) is connected with the input end of the signal driving module (300) and the power switch module (400) respectively. The signal input module (100) is used for receiving an external control signal. The optical coupling isolation module (200) is used for realizing electrical isolation between the signal input module (100) and the output control module (500) and transmitting the external control signal to the signal driving module (300). The signal driving module (300) is used for driving the conduction or turn-off of the power switch module (400). The power switch module (400) is used for controlling the on-off state of an external load according to the output signal of the signal driving module (300). The output control module (500) is used for outputting the working voltage of the external load. The optical coupling isolation module (200) comprises an optical coupling O1, the optical coupling O1 comprises a signal transmitting end positive pole, a signal transmitting end negative pole, a signal receiving end positive pole and a signal receiving end negative pole, the signal transmitting end positive pole and the signal transmitting end negative pole are connected with the signal input module (100), the signal receiving end positive pole is connected with the signal driving module (300), the power switch module (400) and the output control module (500), and the signal receiving end negative pole is connected with the signal driving module (300), the power switch module (400), the output control module (500) and a grounding end.

2. The optical coupling isolation control circuit of claim 1, wherein, The signal input module (100) comprises a resistor R1, a resistor R2, a resistor R5 and a light emitting diode LED1, one end of the resistor R1 is connected with an external signal transmitting end, the other end of the resistor R1 is connected with the anode of the light emitting diode LED1, one end of the resistor R2 and the signal transmitting end positive pole, the cathode of the light emitting diode LED1 is grounded through the resistor R5, and the other end of the resistor R2 is connected with the signal transmitting end negative pole.

3. The optical coupling isolation control circuit of claim 2, wherein, The optical coupling isolation module (200) further comprises a capacitor C1, one end of the capacitor C1 is connected with one end of the resistor R2 and the signal transmitting end positive pole, and the other end of the capacitor C1 is connected with the other end of the resistor R2 and the signal transmitting end negative pole.

4. The optical coupling isolation control circuit of claim 3, wherein, ​ 5. The optical coupling isolation control circuit of claim 2, wherein, The signal driving module (300) comprises a switching tube Q1, a base of the switching tube Q1 is connected with the signal receiving end positive pole and the output control module (500), an emitter of the switching tube Q1 is connected with the output control module (500), a collector of the switching tube Q1 is connected with the control end of the power switch module (400) and the ground end, and the switching tube Q1 is a triode.

6. The optical coupling isolation control circuit of claim 5, wherein, The signal driving module (300) further comprises a resistor R3 and a capacitor C2, and the signal receiving end positive pole is connected with the emitter of the switching tube Q1 through the resistor R3 and the capacitor C2 respectively.

7. The optical coupling isolation control circuit of claim 5, wherein, The power switch module (400) comprises a switching tube Q2, a gate of the switching tube Q2 is connected with the emitter of the switching tube Q1 and the ground end, a drain of the switching tube Q2 is connected with the output control module (500), a source of the switching tube Q2 is grounded, and the switching tube Q2 is a MOS tube.

8. The optical coupling isolation control circuit of claim 7, wherein, The power switch module (400) further comprises a resistor R4 and a diode D1, the gate of the switching tube Q2 is grounded through the resistor R4, an anode of the diode D1 is connected with the output control module (500) and the drain of the switching tube Q2, and a cathode of the diode D1 is connected with the source of the switching tube Q2 and the ground end.

9. The optical coupling isolation control circuit of claim 8, wherein, The power switch module (400) further comprises a resistor R6 and a capacitor C3, one end of the resistor R6 is connected with the cathode of the diode D1, the source of the switching tube Q2, the collector of the switching tube Q1 and the ground end, and the other end of the resistor R6 is connected with the output control module (500), the drain of the switching tube Q2 and the emitter of the switching tube Q1 through the capacitor C3.

10. The optical coupling isolation control circuit of claim 1, wherein, The output control module (500) comprises a fuse F1, one end of the fuse F1 is connected with the signal driving module (300) and the power switch module (400), and the other end of the fuse F1 is connected with an external load.

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