A load protection circuit

Abstract

The application discloses a load protection circuit, which comprises a reed switch module, a protection relay and a load module, the reed switch module is used for outputting a closing signal or an opening signal, a coil port of the protection relay is connected with an output end of the reed switch module, the protection relay is used for outputting a forced opening signal after receiving the opening signal, an input end of the load module is connected with a contact port of the protection relay, and an output end of the load module is connected with a load; the load module forcibly opens all loads when receiving the forced opening signal. The protection relay of the application is a mechanical switch control, which will not cause misoperation or performance decline due to external electromagnetic interference, has higher reliability, and can meet EMC test requirements. In addition, the reed switch is a magnetic control switch, compared with a traditional micro switch, the reed switch realizes closing or opening by using the action of a magnetic field, and can realize on-off control of a circuit without mechanical contact, and has faster response characteristics and higher reliability.

Description

[Technical Field]

[0001] This utility model relates to the field of load protection technology, and in particular to a load protection circuit. [Background Technology]

[0002] A load protection circuit is a protective circuit connected between the power supply and the load circuit. When the current in the load circuit is too high or a short circuit occurs in the power supply, the load protection circuit can promptly disconnect the power supply from the load circuit to prevent damage to either the power supply or the load circuit.

[0003] Currently, load protection circuits often use semiconductor switches or traditional microswitches to control the on / off state of the load. However, semiconductor switches may still have leakage current when turned off, resulting in the load not being truly isolated from the system; under voltage transients, semiconductor devices may also accidentally turn on, preventing the load from being completely disconnected, thus posing a safety hazard. Therefore, they are difficult to pass EMC certification testing requirements. [Utility Model Content]

[0004] To address the technical problem that current load protection circuit designs using semiconductor switches to control load switching have inherent defects, leading to failure to meet EMC certification testing requirements, this invention provides a load protection circuit.

[0005] To achieve the above objectives, this utility model is implemented by the following technical solution:

[0006] A load protection circuit, comprising:

[0007] A reed switch module, wherein the reed switch module is used to output a closed signal or an open signal;

[0008] A protective relay, wherein the coil port of the protective relay is connected to the output terminal of the reed switch module, and the protective relay is used to output a forced disconnect signal after receiving the disconnect signal;

[0009] The load module has its input terminal connected to the contact port of the protection relay and its output terminal electrically connected to the load. When the load module receives the forced disconnect signal, it forcibly disconnects all loads.

[0010] By adopting the above technical solution, the protection relay receives the disconnect signal output by the reed switch module and can output a forced disconnect signal to control the load module to forcibly disconnect all loads. This can avoid the safety risks such as overheating and short circuit caused by the continuous power supply of the load due to reed switch failure or other abnormal conditions, effectively protecting the load-side equipment. Moreover, the protection relay is a mechanical switch control and will not be malfunctioning or degraded due to external electromagnetic interference. It has higher reliability and can better meet EMC test requirements.

[0011] Secondly, a reed switch is a magnetic switch. Compared with traditional microswitches, it uses the effect of a magnetic field to close or open the circuit without mechanical contact, thus achieving circuit on / off control. It has faster response characteristics and higher reliability.

[0012] As described above, in a load protection circuit, the reed switch module includes:

[0013] A reed switch, which has a closed state and an open state;

[0014] The MOS transistor unit has its input terminal connected to the output terminal of the reed switch, and its output terminal connected to the coil port of the protection relay. When the reed switch is closed, the output terminal of the MOS transistor unit outputs a closed signal; when the reed switch is open, the output terminal of the MOS transistor unit outputs an open signal.

[0015] As described above, in a load protection circuit, the MOSFET unit includes MOSFET Q7, MOSFET Q8, resistor R32, and resistor R47. The input terminal of the reed switch is grounded, the output terminal of the reed switch is connected to one end of resistor R32, the other end of resistor R32 is connected to the gate of MOSFET Q7, the source of MOSFET Q7 is connected to the first power output terminal, and the drain of MOSFET Q7 is connected to the source of MOSFET Q8.

[0016] The output terminal of the reed switch is also connected to one end of the resistor R47, the other end of the resistor R47 is connected to the gate of the MOS transistor Q8, and the drain of the MOS transistor Q8 is connected to the coil port of the protection relay.

[0017] In the load protection circuit described above, the first coil terminal of the protection relay is connected to the output terminal of the reed switch module, the second coil terminal of the protection relay is connected to the first drive terminal of the load module, the normally open terminal of the protection relay is connected to the mains power, and the common terminal of the protection relay is connected to the output terminal of the load module.

[0018] The load protection circuit described above further includes:

[0019] A switch protection module, wherein the input terminal of the switch protection module is connected to the output terminal of the reed switch, and the switch protection module is used to output an abnormal signal when the reed switch malfunctions;

[0020] The main control module has its control signal input terminal connected to the output terminal of the switch protection module and its control signal output terminal connected to the drive input terminal of the load module. When the main control module receives the abnormal signal, it outputs a stop signal to control the load module to stop running.

[0021] As described above, in a load protection circuit, the load module includes:

[0022] A drive unit, wherein the drive input terminal of the drive unit is connected to the control signal output terminal of the main control module, and the drive unit is used to stop running when it receives the stop running signal;

[0023] The load unit has its input terminal connected to the drive output terminal of the drive unit, and its output terminal electrically connected to the load.

[0024] As described above, in a load protection circuit, the driving unit includes a driving chip IC1, which is a ULN2003.

[0025] As described above, in a load protection circuit, the load unit includes a load interface COM1 and at least one relay. The first coil terminal of the relay is connected to the drive output terminal of the drive unit, the second coil terminal of the relay is connected to the first power output terminal, the common terminal of the relay is electrically connected to the load interface COM1, and the normally open terminal of the relay is connected to the output terminal of the protection relay.

[0026] As described above, in a load protection circuit, the switch protection module includes a diode D4, a pull-up resistor R28, and a resistor R31. The output terminal of the reed switch is connected to the negative terminal of the diode D4, the positive terminal of the diode D4 is connected to the pull-up resistor R28, the positive terminal of the diode D4 is also connected to one end of the resistor R31, and the other end of the resistor R31 is connected to the control signal input terminal of the main control module.

[0027] Compared with the prior art, the load protection circuit proposed in this utility model has the following beneficial effects:

[0028] 1. The load protection circuit proposed in this utility model receives the disconnect signal output by the reed switch module through the protection relay and can output a forced disconnect signal to control the load module to forcibly disconnect all loads. This can avoid the safety risks such as overheating and short circuit caused by the continuous power supply of the load due to reed switch failure or other abnormal conditions, effectively protecting the load-side equipment. Moreover, the protection relay is a mechanical switch control and will not be malfunctioned or degraded due to external electromagnetic interference, thus having higher reliability and better meeting EMC testing requirements.

[0029] 2. The reed switch module of this utility model utilizes a reed switch as a door control switch, which has a faster response characteristic when detecting the opening and closing of equipment doors. Furthermore, since the spring of the reed switch is sealed in a glass tube filled with inert gas, the internal components will not be oxidized or corroded by external environmental factors, thus having better sealing performance. Secondly, the MOS transistor unit can convert and amplify the output signal of the reed switch to ensure that the protection relay can work reliably, thereby quickly disconnecting all loads after detecting that the door is open. [Attached Image Description]

[0030] To more clearly illustrate the technical solutions in the embodiments of this utility model, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0031] Figure 1 This is a block diagram illustrating the circuit principle structure of this utility model;

[0032] Figure 2 This is another circuit principle structure block diagram of this utility model;

[0033] Figure 3 This is a circuit diagram of the load protection circuit of this utility model;

[0034] Figure 4 This is a circuit diagram of the main control module of this utility model.

Detailed Implementation Methods

[0035] To make the technical problems solved, technical solutions, and beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0036] Specific embodiments, combined with Figures 1 to 4 As shown, the technical solution of this utility model is further illustrated. A load protection circuit includes a reed switch module 100, a protection relay 200, and a load module 300. The reed switch module 100 is used to output a closing signal or a closing signal. The coil port of the protection relay 200 is connected to the output terminal of the reed switch module 100. The protection relay 200 is used to output a forced disconnect signal after receiving the disconnect signal. The input terminal of the load module 300 is connected to the contact port of the protection relay 200. The output terminal of the load module 300 is electrically connected to the load. When the load module 300 receives the forced disconnect signal, it forcibly disconnects all loads.

[0037] In this embodiment, the protection relay receives the disconnect signal from the reed switch module and can output a forced disconnect signal to control the load module to forcibly disconnect all loads. This can avoid the safety risks of overheating and short circuits caused by the continuous power supply of the load due to reed switch failure or other abnormal conditions, effectively protecting the load-side equipment. Moreover, the protection relay is a mechanical switch control and will not malfunction or degrade in performance due to external electromagnetic interference. It has higher reliability and can better meet EMC test requirements.

[0038] Secondly, a reed switch is a magnetic switch. Compared with traditional microswitches, it uses the effect of a magnetic field to close or open the circuit without mechanical contact, thus achieving circuit on / off control. It has faster response characteristics and higher reliability.

[0039] Furthermore, as a preferred embodiment of this solution and not a limitation thereof, the reed switch module 100 includes a reed switch SW1 and a MOS transistor unit 110. The reed switch SW1 has a closed state and an open state. The input terminal of the MOS transistor unit 110 is connected to the output terminal of the reed switch SW1, and the output terminal of the MOS transistor unit 110 is connected to the coil port of the protection relay 200. When the reed switch SW1 is in the closed state, the output terminal of the MOS transistor unit 110 outputs a closed signal. When the reed switch SW1 is in the open state, the output terminal of the MOS transistor unit 110 outputs an open signal.

[0040] In this embodiment, a reed switch is used as a door control switch, which has a faster response characteristic when detecting the opening and closing of the equipment door. Furthermore, since the spring of the reed switch is sealed in a glass tube filled with inert gas, the internal components will not be oxidized or corroded by external environmental factors, thus having better sealing performance. Secondly, the MOSFET unit can convert and amplify the output signal of the reed switch to ensure that the protection relay can work reliably, so that after the door is detected to be open, all loads can be quickly disconnected.

[0041] In a preferred embodiment, the MOS transistor unit 110 includes MOS transistors Q7 and Q8, resistors R32 and R47, the input terminal (i.e., the first terminal) of the reed switch SW1 is grounded, the output terminal (i.e., the second terminal) of the reed switch SW1 is connected to one end of the resistor R32, the other end of the resistor R32 is connected to the gate of the MOS transistor Q7, the source of the MOS transistor Q7 is connected to the first power output terminal (i.e., the +12V terminal), and the drain of the MOS transistor Q7 is connected to the source of the MOS transistor Q8.

[0042] The output terminal (i.e., the second terminal) of the reed switch SW1 is also connected to one end of the resistor R47, the other end of the resistor R47 is connected to the gate of the MOS transistor Q8, and the drain of the MOS transistor Q8 is connected to the coil port of the protection relay 200.

[0043] Specifically, when reed switch SW1 is closed, since the input terminal (terminal 1) of reed switch SW1 is grounded, the gates of MOSFET Q7 and MOSFET Q8 receive a low-level signal. Since the source of MOSFET Q7 is connected to the first power output terminal (+12V terminal), a source current will be formed from the source to the drain. Thus, the conduction current of MOSFET Q7 will flow through the source of MOSFET Q8, and similarly, MOSFET Q8 will form a source current from the source to the drain, thereby outputting a closed signal (i.e., a high-level signal) to the protection relay 200.

[0044] When reed switch SW1 is in the off state, the gates of MOSFET Q7 and MOSFET Q8 receive high-level signals. At this time, the voltage between the gate and source of MOSFET Q7 (i.e., Vgs) decreases, causing MOSFET Q7 to be turned off, and MOSFET Q8 is also turned off, thereby outputting a disconnect signal (i.e., a low-level signal) to the protection relay 200.

[0045] In this embodiment, MOSFETs Q7 and Q8 have fast switching response characteristics, enabling them to quickly respond to changes in the state of reed switch SW1 and achieve rapid signal switching and control. This allows for the rapid forced disconnection of all loads after the door is detected to be open. Secondly, the setting of resistors R32 and R47 can reduce signal interference during the transmission of the output signal of reed switch SW1, enhance the anti-interference capability of the circuit, and improve the reliability of the circuit.

[0046] Furthermore, as a preferred embodiment of this solution and not a limitation, the first coil terminal of the protection relay 200 is connected to the output terminal of the reed switch module 100, the second coil terminal of the protection relay 200 is connected to the first drive terminal of the load module 300, the normally open terminal of the protection relay 200 is connected to the mains power (i.e., ACL), and the common terminal of the protection relay 200 is connected to the output terminal of the load module 300.

[0047] Specifically, when the first coil terminal of the protection relay 200 receives the closing signal (high-level signal) output by the reed switch module 100, it is energized, controlling the normally open terminal of the protection relay 200 to close. Since the normally open terminal of the protection relay 200 is connected to the mains power (ACL), it can control the output of all loads of the load module 300.

[0048] When the first coil terminal of the protection relay 200 receives the disconnect signal (low-level signal) output by the reed switch module 100, it disconnects. At this time, the normally open terminal of the protection relay 200 is disconnected, so that all loads of the load module 300 cannot receive mains power, and all loads are forcibly disconnected.

[0049] In this embodiment, the protection relay receives the disconnect signal from the reed switch module and can output a forced disconnect signal to control the load module to forcibly disconnect all loads. This can avoid safety risks such as overheating and short circuits caused by the reed switch failure or other abnormal conditions leading to continuous power supply to the load. It effectively protects the load-side equipment. Furthermore, the protection relay is a mechanical switch control and will not malfunction or degrade in performance due to external electromagnetic interference. It has higher reliability and better meets EMC testing requirements.

[0050] Furthermore, as a preferred embodiment of this solution and not a limitation, it also includes a switch protection module 400 and a main control module 500. The input terminal of the switch protection module 400 is connected to the output terminal of the reed switch SW1. The switch protection module 400 is used to output an abnormal signal when the reed switch SW1 malfunctions. The control signal input terminal of the main control module 500 is connected to the output terminal of the switch protection module 400. The control signal output terminal of the main control module 500 is connected to the drive input terminal of the load module 300. The main control module 500 is used to output a stop operation signal when it receives the abnormal signal, so as to control the load module 300 to stop running.

[0051] In a preferred embodiment, the switch protection module 400 includes a diode D4, a pull-up resistor R28, and a resistor R31. The output terminal (i.e., SW1 terminal) of the reed switch SW1 is connected to the negative terminal of the diode D4, the positive terminal of the diode D4 is connected to the pull-up resistor R28, the positive terminal of the diode D4 is also connected to one end of the resistor R31, and the other end of the resistor R31 is connected to the control signal input terminal (i.e., Door terminal) of the main control module 500.

[0052] Specifically, when reed switch SW1 is closed, since the input terminal (terminal 1) of reed switch SW1 is grounded, a low-level signal is output. If reed switch SW1 malfunctions at this time, causing the control signal input terminal (Door terminal) of the main control module 500 to receive a high-level signal (i.e., an abnormal signal), the main control module 500 outputs a stop signal to control all loads of the load module 300 to disconnect.

[0053] Similarly, when reed switch SW1 is in the off state, it outputs a high-level signal. If reed switch SW1 malfunctions at this time, causing the control signal input terminal (Door terminal) of the main control module 500 to receive a low-level signal (i.e., an abnormal signal), the main control module 500 outputs a stop-run signal to control all loads of the load module 300 to disconnect.

[0054] In this embodiment, diode D4 is connected in reverse to the output terminal of reed switch SW1. Its unidirectional conductivity can prevent 12V voltage from flowing back into the main control module and burning out the main control chip. Secondly, resistor R31 is used as a current limiting resistor to prevent abnormal overcurrent from burning out the main control module.

[0055] In a preferred embodiment, the main control module 500 includes a main control chip U3, preferably a CBM7220DSLA.

[0056] Furthermore, as a preferred embodiment of this solution and not a limitation thereof, the load module 300 includes a drive unit 310 and a load unit 320. The drive input terminal of the drive unit 310 is connected to the control signal output terminal of the main control module 500. The drive unit 310 is used to stop running when it receives the stop running signal. The input terminal of the load unit 320 is connected to the drive output terminal of the drive unit 310, and the output terminal of the load unit 320 is electrically connected to the load.

[0057] In a preferred embodiment, the driving unit 310 includes a driving chip IC1, preferably a ULN2003.

[0058] In this embodiment, the driver chip ULN2003 is a commonly used Darlington transistor array chip. It can amplify the signal through the internal Darlington transistors based on the output signal of the main control module, so as to convert it into a signal that can control the load unit to be turned on or off, thereby realizing the on / off control of the load-side device.

[0059] In a preferred embodiment, the load unit 320 includes a load interface COM1 and at least one relay. The first coil terminal of the relay is connected to the drive output terminal of the drive unit 310, the second coil terminal of the relay is connected to the first power output terminal (i.e., the +12V terminal), the common terminal of the relay is electrically connected to the load interface COM1, and the normally open terminal of the relay is connected to the output terminal of the protection relay 200.

[0060] In this embodiment, the on / off state of the load is controlled by a relay, thereby achieving electrical isolation between the control circuit and the load. This prevents interference and damage to the control circuit from the high-voltage load circuit, improving the safety of the entire circuit. The relay can drive a large load current with a small control signal, meeting the control requirements of different power loads.

[0061] In some preferred embodiments, the relays in this embodiment include relays RY1, RY2, RY3, RY4, RY5, and RY6. Specifically, the first coil terminal of relay RY1 is connected to the first drive output terminal (i.e., pin 16) of the drive unit 310, the second coil terminal of relay RY1 is connected to the first power output terminal (i.e., +12V terminal), the common terminal of relay RY1 is connected to the first terminal of the load interface COM1, and the normally open terminal of relay RY1 is connected to the output terminal of the protection relay 200.

[0062] The first coil terminal of the relay RY2 is connected to the second drive output terminal (i.e., pin 15) of the drive unit 310, the common terminal of the relay RY2 is connected to the second terminal of the load interface COM1, and the normally open terminal of the relay RY2 is connected to the output terminal of the protection relay 200.

[0063] The first coil terminal of the relay RY3 is connected to the third drive output terminal (i.e., pin 14) of the drive unit 310, the common terminal of the relay RY3 is connected to the third terminal of the load interface COM1, and the normally open terminal of the relay RY3 is connected to the output terminal of the protection relay 200.

[0064] The first coil terminal of the relay RY4 is connected to the fourth drive output terminal (i.e., pin 13) of the drive unit 310, the common terminal of the relay RY4 is connected to the fourth terminal of the load interface COM1, and the normally open terminal of the relay RY4 is connected to the output terminal of the protection relay 200.

[0065] The first coil terminal of the relay RY5 is connected to the fifth drive output terminal (i.e., pin 12) of the drive unit 310, the common terminal of the relay RY5 is connected to the fifth terminal of the load interface COM1, and the normally open terminal of the relay RY5 is connected to the output terminal of the protection relay 200.

[0066] The first coil terminal of the relay RY6 is connected to the sixth drive output terminal (i.e., pin 11) of the drive unit 310, the common terminal of the relay RY6 is connected to the sixth terminal of the load interface COM1, and the normally open terminal of the relay RY6 is connected to the output terminal of the protection relay 200.

[0067] The working principle of this utility model is as follows:

[0068] This utility model proposes a load protection circuit that utilizes the magnetic switch property of reed switch SW1 to forcibly disconnect all loads when the door is opened, while meeting EMC test requirements. The specific control process is as follows:

[0069] When reed switch SW1 is in the off state, since the input terminal (terminal 1) of reed switch SW1 is grounded, the gates of MOSFET Q7 and MOSFET Q8 receive a high-level signal. The voltage (Vgs) between the gate and source of MOSFET Q7 decreases, causing MOSFET Q7 to turn off, and MOSFET Q8 also turns off, thus outputting a disconnect signal to the protection relay 200. After receiving the disconnect signal output by the reed switch module 100, the first coil terminal of the protection relay 200 disconnects. At this time, the normally open terminal of the protection relay 200 is open, so that all loads of the load module 300 cannot receive mains power, and all loads are forcibly disconnected.

[0070] Those skilled in the art should understand that the above description is one embodiment provided in conjunction with specific content, and does not imply that the specific implementation of this utility model is limited to these descriptions. Furthermore, due to differences in industry naming conventions, it is not limited to the above names or English names. Any methods or structures similar to or identical to those of this utility model, or any technical deductions or substitutions made based on the concept of this utility model, should be considered within the scope of protection of this utility model.

Claims

1. A load protection circuit, characterized in that, include: A reed switch module, wherein the reed switch module is used to output a closed signal or an open signal; A protective relay, wherein the coil port of the protective relay is connected to the output terminal of the reed switch module, and the protective relay is used to output a forced disconnect signal after receiving the disconnect signal; The load module has its input terminal connected to the contact port of the protection relay and its output terminal electrically connected to the load. When the load module receives the forced disconnect signal, it forcibly disconnects all loads.

2. The load protection circuit according to claim 1, characterized in that, The reed switch module includes: A reed switch, which has a closed state and an open state; The MOS transistor unit has its input terminal connected to the output terminal of the reed switch, and its output terminal connected to the coil port of the protection relay. When the reed switch is closed, the output terminal of the MOS transistor unit outputs a closed signal; when the reed switch is open, the output terminal of the MOS transistor unit outputs an open signal.

3. The load protection circuit according to claim 2, characterized in that, The MOS transistor unit includes MOS transistors Q7 and Q8, resistors R32 and R47. The input terminal of the reed switch is grounded, the output terminal of the reed switch is connected to one end of resistor R32, the other end of resistor R32 is connected to the gate of MOS transistor Q7, the source of MOS transistor Q7 is connected to the first power output terminal, and the drain of MOS transistor Q7 is connected to the source of MOS transistor Q8. The output terminal of the reed switch is also connected to one end of the resistor R47, the other end of the resistor R47 is connected to the gate of the MOS transistor Q8, and the drain of the MOS transistor Q8 is connected to the coil port of the protection relay.

4. The load protection circuit according to claim 1, characterized in that, The first coil terminal of the protection relay is connected to the output terminal of the reed switch module, the second coil terminal of the protection relay is connected to the first drive terminal of the load module, the normally open terminal of the protection relay is connected to the mains power, and the common terminal of the protection relay is connected to the output terminal of the load module.

5. A load protection circuit according to claim 2, characterized in that, Also includes: A switch protection module, wherein the input terminal of the switch protection module is connected to the output terminal of the reed switch, and the switch protection module is used to output an abnormal signal when the reed switch malfunctions; The main control module has its control signal input terminal connected to the output terminal of the switch protection module and its control signal output terminal connected to the drive input terminal of the load module. When the main control module receives the abnormal signal, it outputs a stop signal to control the load module to stop running.

6. A load protection circuit according to claim 5, characterized in that, The load module includes: A drive unit, wherein the drive input terminal of the drive unit is connected to the control signal output terminal of the main control module, and the drive unit is used to stop running when it receives the stop running signal; The load unit has its input terminal connected to the drive output terminal of the drive unit, and its output terminal electrically connected to the load.

7. A load protection circuit according to claim 6, characterized in that, The driving unit includes a driving chip IC1, which is a ULN2003.

8. A load protection circuit according to claim 6, characterized in that, The load unit includes a load interface COM1 and at least one relay. The first coil terminal of the relay is connected to the drive output terminal of the drive unit, the second coil terminal of the relay is connected to the first power output terminal, the common terminal of the relay is electrically connected to the load interface COM1, and the normally open terminal of the relay is connected to the output terminal of the protection relay.

9. A load protection circuit according to claim 5, characterized in that, The switch protection module includes a diode D4, a pull-up resistor R28, and a resistor R31. The output terminal of the reed switch is connected to the negative terminal of the diode D4, the positive terminal of the diode D4 is connected to the pull-up resistor R28, the positive terminal of the diode D4 is also connected to one end of the resistor R31, and the other end of the resistor R31 is connected to the control signal input terminal of the main control module.

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