Controller protection circuit
By setting up current monitoring and fault diagnosis units on the controller signal channel, the problem of controller burnout caused by external load short circuits or high currents is solved, enabling rapid fault location and protection, and reducing maintenance costs and production impact.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-26
- Publication Date
- 2026-04-14
AI Technical Summary
The existing controller's I/O interface module does not have a current monitoring or current limiting protection resistor connected in series in the signal channel. This makes the controller prone to burning out when the external load is short-circuited or there is an abnormally large current. After the damage, the entire module or board needs to be replaced, resulting in high costs and production interruptions.
A current monitoring unit and a fault judgment unit are set on the signal channel. The current is converted into a voltage signal by a sampling resistor. The fault is judged by overcurrent and circuit breaker comparators. The current is limited or cut off by the prompt unit and overcurrent protection element to prevent the controller from burning out.
It enables real-time current monitoring and fault indication of the controller, quickly detects and locates faults, avoids controller damage, reduces maintenance costs and minimizes production interruptions.
Smart Images
Figure CN121863295A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of control circuit protection technology, and more specifically to a controller protection circuit. Background Technology
[0002] In the field of industrial control and electronic equipment applications, controllers are the core components for signal processing, command output, and load driving. Common controllers include PLCs, microcontrollers, and microcontroller modules, and are widely used in automated production lines, intelligent equipment, and industrial measurement and control systems. These controllers are typically equipped with multiple I / O interfaces, each of which serves as a signal channel to connect to external actuators (such as relays, solenoid valves, motors, sensors, and other loads) to complete the transmission and execution of commands.
[0003] However, existing controller signal channel designs have significant safety flaws: most PLCs, microcontrollers, and other controllers do not have current monitoring or current-limiting protection resistors connected in series in the signal channel on their I / O interface modules, relying solely on the controller's weak internal overcurrent protection circuit. When an external load experiences a short circuit, a short circuit due to insulation damage in the load line, or abnormally high current caused by aging or malfunction of external electrical components, the controller's I / O output points will directly bear the impact of the short-circuit current, easily leading to output module burnout and I / O pin breakdown.
[0004] If a controller's output point is damaged due to a short circuit, the damaged output point cannot be repaired individually because the controller's I / O modules are mostly integrated. Often, the entire I / O module or even the controller's core board needs to be replaced, resulting in high hardware replacement costs and production line interruptions due to equipment downtime. Especially in industrial production scenarios, downtime caused by controller failures can directly impact production cycles. Summary of the Invention
[0005] To overcome the above-mentioned shortcomings in the prior art, the present invention provides a controller protection circuit that prevents the internal circuit of the controller from burning out and facilitates rapid fault detection.
[0006] The technical solution of this invention is as follows: A controller protection circuit for monitoring and protecting the current between the controller and an external load, comprising: At least one signal channel, one end of which is used to connect to the output of the controller, and the other end is used to connect to an external load; A current monitoring unit installed on the signal channel is used to acquire the current status of the signal channel; The fault judgment unit connected to the current monitoring unit is used to determine whether an overcurrent fault or an open circuit fault has occurred based on the current status. The prompting unit connected to the fault judgment unit is used to provide a fault prompt when the fault signal is received.
[0007] Preferably, the current monitoring unit includes a sampling resistor connected in series with the signal channel, the sampling resistor being used to convert the current into a voltage signal to characterize the current state.
[0008] In any of the above schemes, it is preferred that the fault judgment unit includes an overcurrent comparator and a circuit breaker comparator. The input terminal of the overcurrent comparator is connected to one end of the sampling resistor and is used to compare the voltage signal with a preset overcurrent threshold and output an overcurrent fault signal. The input terminal of the circuit breaker comparator is connected to the other end of the sampling resistor, and is used to compare the voltage signal with a preset circuit breaker threshold and output a circuit breaker fault signal.
[0009] In any of the above schemes, it is preferred that the overcurrent threshold is provided by a first voltage divider circuit, which is connected to the system power supply; and the circuit breaking threshold is provided by a second voltage divider circuit, which is connected to the system power supply.
[0010] In any of the above schemes, the fault judgment unit further includes a logic circuit, the input of which is connected to the output of the overcurrent comparator and the output of the circuit breaker comparator, respectively, for logically combining the overcurrent fault signal and the circuit breaker fault signal to output a comprehensive fault signal.
[0011] In any of the above embodiments, it is preferred that the prompting unit includes a light prompting element and / or a sound prompting element, the light prompting element and / or the sound prompting element being connected to the output terminal of the fault judgment unit, for providing light and / or sound prompts when the fault signal is valid.
[0012] In any of the above embodiments, it is preferred to further include an overcurrent protection element connected in series with the signal channel, for limiting or cutting off the current in the signal channel in the event of an overcurrent.
[0013] In any of the above solutions, it is preferred that the overcurrent protection element is a resettable fuse or a PMOS transistor.
[0014] In any of the above schemes, it is preferred that the signal channel is a multi-channel parallel structure, with the input end of each signal channel independently connected to an I / O interface of the controller, the output end of each signal channel independently connected to an external load, and each signal channel is equipped with a set of current monitoring units and fault judgment units.
[0015] This invention discloses a controller protection circuit that includes a current monitoring unit on the signal channel to monitor the current status in real time and compare it with a preset threshold through a fault judgment unit. Once the current exceeds a safe range, the fault judgment unit outputs a fault signal, which, in conjunction with an overcurrent protection element, limits or cuts off the current, thereby preventing large currents from directly impacting the controller's internal circuitry and preventing burnout.
[0016] The current monitoring unit converts current into a voltage signal, and the fault diagnosis unit can distinguish between different fault types such as overcurrent and open circuit, and output corresponding fault signals. The prompting unit provides visual / audible prompts based on the fault signals. Operators can quickly determine whether a fault has occurred and its approximate type by referring to the prompt information without having to measure the circuit line one by one, thus enabling rapid fault detection and location. Attached Figure Description
[0017] Figure 1 This is a circuit diagram of one embodiment of the controller protection circuit of the present invention.
[0018] Explanation of the labels in the diagram: 101 - Overcurrent comparator; 102 - Circuit breaker comparator; Detailed Implementation The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0019] In the description of this invention, terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used solely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, terms such as "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0020] Example 1: like Figure 1 As shown, the protection circuit of this invention is used for current monitoring and fault protection of the signal channel between the controller output and the external load. This protection circuit can be applied to the drive circuits of microcontrollers, programmable logic controllers, digital signal processors, application-specific integrated circuits, and various chips (such as motor drive chips, relay drive chips, power switch drive circuits, etc.).
[0021] The controller outputs control signals through its I / O interface, and these control signals are transmitted to the actuators or loads at the back end through at least one signal channel. Each signal channel corresponds to one I / O interface of the controller and is used to provide operating current or control current to the actuator connected to that I / O interface.
[0022] A current monitoring unit is provided on the signal channel to obtain the current state of the signal channel, and the output electrical signal corresponds to the magnitude or presence of the current in the signal channel.
[0023] The current monitoring unit is connected to a fault determination unit. The fault determination unit determines whether an overcurrent fault or an open-circuit fault has occurred based on the current status output by the current monitoring unit. For example, when the current monitoring unit detects that the current value in the signal channel exceeds a preset overcurrent threshold, the fault determination unit determines it as an overcurrent fault; when the current monitoring unit detects that the current value in the signal channel is lower than a preset open-circuit threshold (or almost zero), the fault determination unit determines it as an open-circuit fault. The fault determination unit outputs a corresponding fault signal when determining a fault.
[0024] The fault judgment unit is connected to a prompting unit, which provides a fault prompt upon receiving a fault signal. The prompting unit can be an indicator light, buzzer, digital tube, display screen, etc., which alerts the operator that an overcurrent fault or open circuit fault has occurred in the current signal channel by illuminating the indicator light, emitting a sound, or displaying fault information, so that timely inspection and handling can be carried out.
[0025] With the above structure, the present invention can monitor the current between the controller and the external load in real time, and output fault signals and provide fault prompts in a timely manner when overcurrent or open circuit faults occur, thereby protecting the controller and facilitating fault diagnosis.
[0026] In this embodiment, each signal channel adopts a multi-parallel structure. The input of each signal channel is independently connected to an I / O interface of the controller, and the output is independently connected to an external load. Each signal channel is equipped with a set of current monitoring units and fault judgment units. Each signal channel and its associated current monitoring units, fault judgment units, and indication units are integrated on a PCB board, which has wiring ports corresponding to the controller and external loads. When any actuator behind the controller fails, the controller sends a control signal to the corresponding signal channel, collects the current signal through the corresponding current monitoring unit, and the fault judgment unit determines the fault. Subsequently, it drives the indicator light corresponding to the signal channel to indicate the fault, thereby realizing rapid identification and location of the fault point.
[0027] In this embodiment, as Figure 1As shown, to ensure effective current acquisition at each signal channel, the current monitoring unit includes a sampling resistor connected in series with the signal channel. One end of the sampling resistor is connected to the output terminal of the controller, and the other end is connected to an external load, ensuring that all current flowing through the signal channel passes through the sampling resistor. The voltage drop across the sampling resistor is proportional to the magnitude of the current in the signal channel, thereby converting the current signal into a voltage signal to characterize the current state. This allows for accurate sampling even of weak currents output by the controller, avoiding the problems of insensitivity or inability to detect weak currents when using current transformers or Hall effect sensors, thus improving the accuracy and reliability of current monitoring.
[0028] In this embodiment, as Figure 1 As shown, the fault judgment unit includes an overcurrent comparator 101 and a circuit breaker comparator 102. The input terminal of the overcurrent comparator 101 is connected to one end of the sampling resistor to receive the voltage signal converted by the sampling resistor. The other input terminal of the overcurrent comparator 101 is connected to a preset overcurrent threshold voltage, which is provided by an external reference voltage circuit. When the current in the signal channel increases, the voltage across the sampling resistor increases accordingly. The overcurrent comparator 101 compares this voltage signal with the preset overcurrent threshold voltage. Once the voltage signal output by the sampling resistor exceeds the overcurrent threshold voltage, the output terminal of the overcurrent comparator 101 will switch from low to high, outputting an overcurrent fault signal to indicate that an overcurrent fault has occurred in the current signal channel.
[0029] The input terminal of the circuit breaker comparator 102 is connected to the other end of the sampling resistor to receive the corresponding voltage signal. The other input terminal of the circuit breaker comparator 102 is connected to a preset circuit breaker threshold voltage, which is also provided by an external reference voltage circuit. When the current in the signal channel decreases or disappears, the voltage across the sampling resistor decreases accordingly, and the circuit breaker comparator 102 compares this voltage signal with the preset circuit breaker threshold voltage. Once the voltage signal output by the sampling resistor is less than the circuit breaker threshold voltage (e.g., close to zero), the output terminal of the circuit breaker comparator 102 will switch from low to high, outputting a circuit breaker fault signal to indicate that a circuit breaker fault has occurred in the current signal channel.
[0030] In this embodiment, as Figure 1As shown, the overcurrent threshold is provided by a first voltage divider circuit, which is connected to the system power supply. Specifically, the first voltage divider circuit consists of at least two resistors connected in series. One end of each resistor is connected to the positive terminal of the system power supply, and the other end is grounded. The connection point of the two resistors serves as the output terminal of the first voltage divider circuit, and the output voltage is the overcurrent threshold voltage. This overcurrent threshold voltage is connected to the reference input terminal of the overcurrent comparator 101. When the current in the signal channel increases, the voltage across the sampling resistor connected in series in the signal channel also increases. The overcurrent comparator 101 compares the voltage signal output by the sampling resistor with the overcurrent threshold voltage provided by the first voltage divider circuit. When the sampled voltage is greater than the overcurrent threshold voltage, the overcurrent comparator 101 outputs an overcurrent fault signal, indicating that an overcurrent fault has occurred in the current signal channel.
[0031] The circuit breaker threshold is provided by a second voltage divider circuit, which is connected to the system power supply. Specifically, the second voltage divider circuit consists of at least two resistors connected in series. One end of each resistor is connected to the positive terminal of the system power supply, and the other end is grounded. The junction of the two resistors serves as the output terminal of the second voltage divider circuit, and the output voltage is the circuit breaker threshold voltage. This circuit breaker threshold voltage is connected to the reference input terminal of the circuit breaker comparator 102. When the current in the signal channel decreases or disappears, the voltage across the sampling resistor decreases accordingly. The circuit breaker comparator 102 compares the voltage signal output by the sampling resistor with the circuit breaker threshold voltage provided by the second voltage divider circuit. When the sampled voltage is less than the circuit breaker threshold voltage, the circuit breaker comparator 102 outputs a circuit breaker fault signal, indicating that a circuit breaker fault has occurred in the current signal channel.
[0032] In this embodiment, the fault judgment unit includes a logic circuit. The input terminal of the logic circuit is connected to the output terminal of the overcurrent comparator 101 and the output terminal of the circuit breaker comparator 102, respectively, and is used to logically combine the overcurrent fault signal and the circuit breaker fault signal to output a comprehensive fault signal.
[0033] Specifically, when an overcurrent fault occurs in the signal channel, the overcurrent comparator 101 outputs a high-level overcurrent fault signal; when an open-circuit fault occurs in the signal channel, the open-circuit comparator 102 outputs a high-level open-circuit fault signal. The logic circuit receives these two fault signals and performs calculations according to a preset logical relationship. For example, the logic circuit can use "OR" logic, outputting a high-level combined fault signal when either fault signal is high. Alternatively, it can use "NOR" logic, outputting a low level only when both fault signals are low, otherwise outputting a high level.
[0034] In this embodiment, the prompting unit includes a light prompting element and / or a sound prompting element, which is connected to the output terminal of the fault judgment unit and is used to provide light and / or sound prompts when the fault signal is valid.
[0035] Example 2: Based on Example 1, such as Figure 1 As shown, to ensure the output port of the controller, this embodiment adds an overcurrent protection element connected in series with the signal channel to limit or cut off the current in the signal channel during overcurrent. Since the current in the signal channel is relatively weak, the overcurrent protection element in this embodiment can be a resettable fuse or a PMOS transistor.
[0036] When a resettable fuse is used as an overcurrent protection element, it is connected in series in the signal channel, with one end connected to the controller's output and the other end connected to one end of the sampling resistor. Under normal operating conditions, the resistance of the resettable fuse is very small, and its effect on the weak current in the signal channel is negligible. When an abnormal overcurrent occurs in the signal channel, the resettable fuse heats up due to the excessive current, and its resistance increases rapidly, thereby limiting the current in the signal channel, or even nearly cutting it off, thus protecting the controller output and other components in the signal channel. After the fault is cleared, the temperature of the resettable fuse drops, and its resistance automatically returns to a low-resistance state, restoring the signal channel to conduction, achieving the automatic recovery function.
[0037] When a PMOS transistor is used as an overcurrent protection element, the PMOS transistor is connected in series in the signal channel. Its source is connected to the output terminal of the controller, its drain is connected to one end of the sampling resistor, and its gate is connected to the output terminal of the fault judgment unit or the control terminal of the controller. Under normal operating conditions, a low level is applied to the gate, the PMOS transistor conducts, the signal channel is open, and a small current can pass through smoothly. When the fault judgment unit detects an overcurrent fault, it outputs a high-level signal to the gate of the PMOS transistor, causing the PMOS transistor to turn off, thereby cutting off the current in the signal channel and achieving overcurrent protection for the signal channel. After the fault is cleared, the fault judgment unit or controller outputs a low-level signal to the gate, the PMOS transistor turns back on, and the signal channel resumes operation.
[0038] The above-described embodiments are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A controller protection circuit for monitoring and protecting the current between the controller and an external load, characterized in that, include: At least one signal channel, one end of which is used to connect to the output of the controller, and the other end is used to connect to an external load; A current monitoring unit installed on the signal channel is used to acquire the current status of the signal channel; The fault judgment unit connected to the current monitoring unit is used to determine whether an overcurrent fault or an open circuit fault has occurred based on the current status. The prompting unit connected to the fault judgment unit is used to provide a fault prompt when the fault signal is received.
2. The controller protection circuit according to claim 1, characterized in that, The current monitoring unit includes a sampling resistor connected in series with the signal channel. The sampling resistor is used to convert the current into a voltage signal to characterize the current state.
3. The controller protection circuit according to claim 2, characterized in that, The fault judgment unit includes an overcurrent comparator (101) and a circuit breaker comparator (102). The input terminal of the overcurrent comparator (101) is connected to one end of the sampling resistor and is used to compare the voltage signal with a preset overcurrent threshold and output an overcurrent fault signal. The input terminal of the circuit breaker comparator (102) is connected to the other end of the sampling resistor to compare the voltage signal with a preset circuit breaker threshold and output a circuit breaker fault signal.
4. The controller protection circuit according to claim 3, characterized in that, The overcurrent threshold is provided by a first voltage divider circuit, which is connected to the system power supply; the circuit breaking threshold is provided by a second voltage divider circuit, which is connected to the system power supply.
5. The controller protection circuit according to claim 3, characterized in that, The fault judgment unit also includes a logic circuit. The input terminal of the logic circuit is connected to the output terminal of the overcurrent comparator (101) and the output terminal of the circuit breaker comparator (102) respectively, and is used to logically combine the overcurrent fault signal and the circuit breaker fault signal to output a comprehensive fault signal.
6. The controller protection circuit according to claim 1, characterized in that, The prompting unit includes a light prompting element and / or a sound prompting element, which is connected to the output terminal of the fault judgment unit and is used to provide light and / or sound prompts when the fault signal is valid.
7. The controller protection circuit according to claim 1, characterized in that, It also includes an overcurrent protection element connected in series with the signal channel, used to limit or cut off the current in the signal channel in the event of an overcurrent.
8. The controller protection circuit according to claim 7, characterized in that, The overcurrent protection element is a resettable fuse or a PMOS transistor.
9. The controller protection circuit according to claim 1, characterized in that, The signal channels are multi-channel parallel structures. The input of each signal channel is independently connected to an I / O interface of the controller, and the output is independently connected to an external load. Each signal channel is equipped with a set of current monitoring units and fault judgment units.