A high-power digital output device and method for detecting and protecting short-circuit

Abstract

The application discloses a kind of high-power digital quantity output device and method of short-circuit detection and protection, overcome the problem that prior art cannot realize effective protection to digital output device and cannot disconnect circuit in time to protect when short-circuit occurs, including hardware circuit part and software control part for controlling circuit, hardware circuit part includes MCU, alarm device, switching device, voltage comparator U2, voltage comparator U3, several resistors, error amplifier circuit and current mirror circuit;Software control part includes MCU module, and MCU module is connected with several channels, and each channel includes short-circuit detection module, control signal switch module, wire break detection module and digital quantity output module.The application samples load current, can configure different load current threshold according to different load demand, and configure different digital quantity output type.It has the characteristics of safety, low cost, high precision and high stability output.

Description

Technical Field

[0001] This invention relates to the fields of automation and instrumentation technology, and in particular to a high-power digital output device and method that supports short-circuit detection and protection. Background Technology

[0002] In the field of industrial control, digital output devices (DIPs) serve as key modules for output control at field control stations. They are primarily used to output control signals to various actuators in the industrial field, and their performance and control characteristics affect the normal operation of various equipment. As loads supporting high-power DIPs, safety and reliability are paramount. Due to the complexity of the industrial environment, actuators such as solenoid valves and power relays may experience open-circuit and short-circuit faults, thereby burning out the DIPs.

[0003] Digital voltage output systems are commonly used to drive and control actuators in production sites and public works. Currently, some widely used digital output devices lack detection of load open circuits and short circuits, failing to provide effective protection for the digital output devices. Others often use precision resistors or Hall effect devices to sample current and feed it back to the microprocessor for short circuit detection and protection. However, due to the slow processing speed of microprocessors, they cannot disconnect the circuit in time to provide protection when a short circuit occurs. Furthermore, precision resistors suffer from severe temperature drift, low sampling accuracy, and high power consumption. Hall effect devices can detect large currents and have low power consumption, but they are expensive, have large measurement errors for small current ranges, are susceptible to external magnetic fields, are sensitive to static electricity, and have complex peripheral circuits.

[0004] Because some traditional PLCs and DCS digital output devices lack detection of load open circuits and short circuits, they cannot effectively protect the digital output devices. Others often collect digital output voltage through resistor voltage division and feed it back to the microprocessor. The voltage is compared with the voltage threshold set inside the microprocessor to achieve the purpose of short circuit detection and protection. However, because the microprocessor has a slow processing speed, it cannot disconnect the circuit in time to protect it when a short circuit occurs.

[0005] For example, a "MOSFET digital output circuit" disclosed in Chinese patent literature, publication number CN107863957B, includes a MOSFET and a monitoring circuit. The MOSFET is connected to both the main controller and the load, and is used to control the on / off state of the load based on the digital output signal output by the main controller. The monitoring circuit is connected to both the MOSFET and the main controller, and is used to monitor the on / off signal of the MOSFET and feed back a digital output status feedback signal to the main controller based on the on / off signal of the MOSFET. This solution uses a digital output approach that combines an integrated chip and an MCU to perform open / short circuit detection and protection on the digital output load line. However, the detection and protection speed is slow, and the digital output pulse width and frequency are fixed and cannot be configured. Summary of the Invention

[0006] The present invention aims to overcome the problem that the prior art cannot effectively protect digital output devices, and provides a high-power digital output device and method for open / short circuit detection and protection, so as to realize open / short circuit detection and protection of the load of the digital output device.

[0007] Another objective of this invention is to overcome the problem that existing technologies cannot promptly disconnect the circuit for protection in the event of a short circuit, thereby achieving high-power digital output. It samples the load current, eliminating the need for a series resistor in the measured digital output load line, reducing the impact of the sampling circuit on the load's operating state. Different load current thresholds and digital output types can be configured according to different load requirements. It features safe, low-cost, high-precision, and highly stable output characteristics.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A high-power digital output device for short-circuit detection and protection includes a hardware circuit section and a software control section for the control circuit.

[0010] The hardware circuit includes an MCU, an alarm device, a switching device, a voltage comparator U2, a voltage comparator U3, several resistors, an error amplifier circuit, and a current mirror circuit. The MCU is connected to the alarm device, the switching device, and the output of comparator U2. The positive input of voltage comparator U2 is connected to the first reference voltage through a resistor, and the negative input of voltage comparator U2 is connected to the error amplifier circuit through a resistor. The switching device is also connected to the current mirror circuit and the output of voltage comparator U3. The positive input of voltage comparator U3 is connected to the second reference voltage through a resistor. The current mirror circuit uses MOSFETs, including a power MOSFET and a sampling MOSFET. The error sampling circuit is connected to the current mirror circuit.

[0011] The software control section includes an MCU module, which connects to several channels. Each channel includes a short-circuit detection module, a control signal switch module, a disconnection detection module, and a digital output module. The digital output module is used to configure the digital signals of the multiple output channels through software, including settings such as fault-safe mode and output type.

[0012] Fail-safe modes include output hold and output according to preset values; output types include pulse width output and status output modes.

[0013] Preferably, the error amplifier circuit includes a voltage comparator U1, resistors R5, R6, R7, and R8.

[0014] The output of voltage comparator U1 is connected to one end of resistor R5 and the negative input of voltage comparator U2. The other end of resistor R5 is connected to the negative input of voltage comparator U1 and one end of resistor R6. The other end of resistor R6 is connected to the drain of the sampling MOSFET. The positive input of voltage comparator U1 is connected to one end of resistor R7 and one end of resistor R8. The other end of resistor R7 is connected to the source of the power MOSFET. The other end of resistor R8 is grounded.

[0015] Preferably, the current mirror circuit includes a power MOSFET Q1, a sampling MOSFET Q2, and a load resistor R. L and precision sampling resistor R S The gates of power MOSFET Q1 and sampling MOSFET Q2 are connected to the switching devices to transmit control signals, and the source of power MOSFET Q1 is connected to the load resistor R. L One end is connected, with the drain of power MOSFET Q1 connected to the +24V power supply, and the source of sampling MOSFET Q2 connected to the resistor at the negative input of voltage comparator U3 and the precision sampling resistor R. S One end is connected, with a load resistor R. L The other end and the precision sampling resistor R S The other end is grounded.

[0016] A high-power digital output method for short-circuit detection and protection is disclosed, employing a high-power digital output device for short-circuit detection and protection, comprising the following: The control signal for the channel digital output is generated by an MCU and controls the MOSFET via a control signal output switch module; a short-circuit detection module performs short-circuit detection and protection on the load line of the digital output module; when a short circuit occurs, the control signal output switch module shuts off the output of the MOSFET control signal, thus turning off the digital output; an open-circuit detection module performs open-circuit detection on the load line of the digital output module; when an open-circuit fault occurs, feedback is sent to the MCU, and the MCU controls an alarm device to send an open-circuit alarm signal.

[0017] Preferably, the open circuit detection includes the following: the power MOSFET Q1 control signal is divided into low level and high level;

[0018] When the control signal for power MOSFET Q1 is low by default, a narrow pulse is output. This narrow pulse briefly turns on power MOSFET Q1. During the conduction period, the potentials of the drain and source of power MOSFET Q1 are sampled. After power MOSFET Q1 is turned on, there is an internal resistance R. DS (on); When there is no open circuit fault in the load line, the current flowing through the on-resistance of the power MOSFET Q1 will generate a voltage drop, causing the potentials of the drain and source of the power MOSFET Q1 to be inconsistent. The voltage difference V between the two is amplified by the error amplifier circuit. DS The voltage is compared with the first reference voltage set by comparator U2, and a low-level signal is output to the MCU to indicate that there is no open circuit fault. When an open circuit fault occurs in the load line, no current flows through the on-resistance of power MOSFET Q1, the drain and source potentials of power MOSFET Q1 are the same, and the voltage difference between them is V. DS When the value is 0, the subsequent error amplifier circuit outputs a low level, which is compared with the set first reference voltage through voltage comparator U2. If it is less than the set first reference voltage, comparator U2 outputs a high level signal to feed back to the MCU, indicating that a disconnection fault has occurred. The MCU then controls the issuance of a disconnection alarm signal.

[0019] When the control signal for power MOSFET Q1 is high by default, the MCU periodically samples the potentials of the drain and source of power MOSFET Q1. This is because the on-resistance R of power MOSFET Q1... DS With the on signal present, when there is no open circuit fault in the load line, the current flowing through the on-resistance of the power MOSFET Q1 generates a voltage drop, causing the potentials of the drain and source of the power MOSFET Q1 to be inconsistent. This voltage difference V is amplified by the error amplifier circuit. DS The voltage comparator U2 compares the voltage with a set first reference voltage, outputting a low-level signal to the MCU to indicate that there is no open circuit fault. When an open circuit fault occurs in the load line, no current flows through the on-resistance of the power MOSFET Q1, causing the drain D and source S of the power MOSFET Q1 to have the same potential, and the voltage difference V between them to be V. DS When the value is 0, the subsequent error amplifier circuit outputs a low level, which is compared with the set first reference voltage through the voltage comparator U2. If it is less than the set first reference voltage, the comparator outputs a high level signal to feed back to the MCU, indicating that a disconnection fault has occurred. The MCU then issues a disconnection alarm signal.

[0020] Preferably, the short-circuit detection and protection includes the following:

[0021] Assuming the channel width-to-length ratio of power MOSFET Q1 is (W / L)1 and the channel width-to-length ratio of sampling MOSFET Q2 is (W / L)2, according to the working principle of the current mirror circuit, the load current I... L With the flow through the precision sampling resistor R S Sampling current I S The following relationship must be satisfied:

[0022]

[0023] Precision sampling resistor R S Sampling voltage V at both ends S With the flow through the precision sampling resistor R S Sampling current I S The following relationship must be satisfied:

[0024] V S =I S R S

[0025] The on-resistance of power MOSFET Q1 is R DS (on), when the digital output module is working normally, that is, when the power MOSFET Q1 and the sampling MOSFET Q2 are turned on, the load current I... L The following relationship must be satisfied:

[0026]

[0027] At this time, the flow through the precision sampling resistor R S Sampling current I S The following relationship must be satisfied:

[0028]

[0029] At this time, the precision sampling resistor R S The sampling voltage at both ends is

[0030]

[0031] Set the second reference voltage to

[0032]

[0033] When there is no short-circuit fault in the load line, and power MOSFET Q1 and sampling MOSFET Q2 are normally turned on, that is, the voltage at the source S of power MOSFET Q1 and sampling MOSFET Q2 is 24V, the precision sampling resistor R... S The sampling voltage at both ends is V SAs the input signal of the voltage comparator U3 circuit, it is equal to the set second reference voltage. The voltage comparator U3 outputs a low level, Q1 is turned on, and the MCU outputs a control signal to control the power MOSFET Q1 and the sampling MOSFET Q2 to work normally.

[0034] When a short circuit fault occurs in the load line, and power MOSFET Q1 and sampling MOSFET Q2 are normally turned on, that is, the voltage at the source S of power MOSFET Q1 and sampling MOSFET Q2 is 24V, and the load resistance R... L The load current I approaches infinity and is approximately zero. L The short-circuit current tends to infinity, and the precision sampling resistor R S Sampling voltage V at both ends S The voltage approaches infinity, which is much larger than the set second reference voltage. The voltage comparator U3 outputs a high level, Q1 is turned off, and the power MOSFET Q1 and the sampling MOSFET Q2 enter the off state without control signal. The digital output stops and enters the short circuit protection state.

[0035] Therefore, the present invention has the following beneficial effects:

[0036] This invention employs discrete semiconductor devices to achieve load open / short circuit detection and protection for digital output devices. In particular, it utilizes power MOSFETs to achieve high-power digital output. Furthermore, it employs a current mirror circuit to sample the load current, eliminating the need for a series resistor in the measured digital output load line, thus reducing the impact of the sampling circuit on the load's operating state. Different load current thresholds and digital output types can be configured according to different load requirements. It features safe, low-cost, high-precision, and highly stable output characteristics. Attached Figure Description

[0037] Figure 1 This is a framework diagram of the digital output configuration menu of the present invention.

[0038] Figure 2 This is a diagram of the digital output configuration interface of the configuration software of this invention.

[0039] Figure 3 This is a block diagram of the software control part of the present invention.

[0040] Figure 4 This is a structural diagram of the hardware circuit part of the present invention.

[0041] In the diagram: 1. MCU module; 2. Short circuit detection module; 3. Control signal switch module; 4. Open circuit detection module; 5. Digital output module; 6. Alarm device; 7. Switching device; 8. Error amplifier circuit; 9. Current mirror circuit. Detailed Implementation

[0042] The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0043] Example:

[0044] This embodiment provides a high-power digital output device for short-circuit detection and protection, including a hardware circuit part and a software control part for the control circuit.

[0045] Software control section such as Figure 3 The software control section includes an MCU module 1, which is connected to several channels. Each channel includes a short-circuit detection module 2, a control signal switch module 3, a disconnection detection module 4, and a digital output module 5. The digital output module 5 is used to configure the digital signals of the multiple output channels through software, such as fault-safe mode and output type settings.

[0046] like Figure 1 As shown, the fail-safe modes include output hold and output according to preset values; the output types include pulse width output and status output modes. Digital output signals are divided into voltage output and relay output. Voltage output directly provides a voltage signal to the external system by controlling the on / off state of a transistor, while relay output provides a signal by controlling the on / off state of relay contacts. Voltage output is faster and has simpler external wiring; therefore, this embodiment uses voltage output to implement digital output. Unless otherwise specified, the voltage output method used in this invention only needs to meet the technical solution requirements; the specific output method used has no impact on the implementation of the solution. The fail-safe modes, output types, and other settings for the digital signals of multiple output channels can also be configured via software.

[0047] The fail-safe modes include output hold and output according to preset values. In output hold mode, when a digital output device malfunctions, the device enters fail-safe mode and the digital output port outputs the configured set value. In status output mode, a high-level or low-level output for a fixed duration can be set via configuration software.

[0048] Output types include two modes: pulse width output and status output. In pulse width output mode, the pulse width and number of pulses of the output digital signal can be set via configuration software. In status output mode, a fixed duration of high or low level output can be set via configuration software. The configuration software's digital output configuration interface is shown below. Figure 2 As shown.

[0049] The control signals for the channel's digital outputs are generated by the MCU and controlled by the control signal output switch module to control the MOSFETs. Since a single type of digital output cannot meet the needs of multiple industries, appropriate types of digital output signals are configured for different terminal control requirements. The short-circuit detection module detects short circuits in the load circuit of the digital output module. When a short circuit occurs, the control signal output switch module shuts off the MOSFET control signal output, thereby cutting off the digital output and achieving short-circuit protection to prevent damage to the module. The open-circuit detection module detects open circuits in the load circuit of the digital output module. When an open-circuit fault occurs, feedback is sent to the MCU, which then controls the alarm device to issue an open-circuit alarm signal.

[0050] Hardware circuit section such as Figure 4 As shown, V1 is the first reference voltage, V2 is the second reference voltage, and K is the control signal. The hardware circuit includes an MCU, an alarm device 6, a switching device 7, a comparator circuit, several resistors, an error amplifier circuit 8, and a current mirror circuit 9. The comparator circuit includes voltage comparators U2 and U3. The MCU is connected to the alarm device, the switching device, and the output of comparator U2. The positive input of voltage comparator U2 is connected to the first reference voltage through a resistor, and the negative input of voltage comparator U2 is connected to the error amplifier circuit through a resistor. The switching device is also connected to the current mirror circuit and the output of voltage comparator U3. The positive input of voltage comparator U3 is connected to the second reference voltage through a resistor. The current mirror circuit uses MOSFETs, including power MOSFETs and sampling MOSFETs. The error sampling circuit is connected to the current mirror circuit.

[0051] The error amplifier circuit includes a voltage comparator U1, resistors R5, R6, R7, and R8;

[0052] The output of voltage comparator U1 is connected to one end of resistor R5 and the negative input of voltage comparator U2. The other end of resistor R5 is connected to the negative input of voltage comparator U1 and one end of resistor R6. The other end of resistor R6 is connected to the drain of the sampling MOSFET. The positive input of voltage comparator U1 is connected to one end of resistor R7 and one end of resistor R8. The other end of resistor R7 is connected to the source of the power MOSFET. The other end of resistor R8 is grounded.

[0053] The current mirror circuit includes a power MOSFET Q1, a sampling MOSFET Q2, and a load resistor R. L and precision sampling resistor R S The gates of power MOSFET Q1 and sampling MOSFET Q2 are connected to the switching devices to transmit control signals, and the source of power MOSFET Q1 is connected to the load resistor R. LOne end is connected, with the drain of power MOSFET Q1 connected to the +24V power supply, and the source of sampling MOSFET Q2 connected to the resistor at the negative input of voltage comparator U3 and the precision sampling resistor R. S One end is connected, with a load resistor R. L The other end and the precision sampling resistor R S The other end is grounded.

[0054] In this embodiment, the switching device is a transistor; the alarm device can be a buzzer or a light-emitting diode, and the alarm device of the hardware circuit is controlled by the MCU to provide alarm prompts.

[0055] This embodiment also provides a high-power digital output method for short-circuit detection and protection, and a solution for a high-power digital output device for short-circuit detection and protection, which elaborates on the working process, principle and control part of the device.

[0056] Includes the following:

[0057] To achieve open circuit detection, this invention outputs a narrow pulse when the power MOSFET Q1 control signal is at a default low level (2ms pulse in this embodiment). The specific value of the narrow pulse has no impact on the scheme; it only needs to ensure brief conduction. The narrow pulse signal controls the power MOSFET Q1 to conduct briefly. Since digital output modules are often used to drive inductive loads such as solenoid valves and power relays, the narrow pulse width can be configured to be shorter than the load response time, depending on the load. During the period when the power MOSFET Q1 is turned on by the narrow pulse signal, the potentials of the drain and source of the power MOSFET Q1 at the digital output port are sampled by a voltage sampling circuit. Since the internal resistance R of the power MOSFET Q1 during conduction... DS With the on signal (on) present, when there is no open circuit fault in the load line, the current flowing through the on-resistance of the power MOSFET Q1 will generate a voltage drop, causing the potentials of the drain and source of the power MOSFET Q1 to be inconsistent. This voltage difference V is amplified by the error amplifier circuit. DS The voltage is compared with a set first reference voltage via a comparator circuit, and a low-level signal is output to the MCU to indicate that there is no open circuit fault. When an open circuit fault occurs in the load line, no current flows through the MOSFET's on-resistance, causing the potentials of the MOSFET's drain (D) and source (S) to be the same, and the voltage difference V between them to be... DS When the value is 0, the subsequent error amplifier circuit outputs a low level, which is compared with the set first reference voltage by the voltage comparator. If the value is less than the set first reference voltage, the comparator outputs a high level signal to feed back to the MCU, indicating that a disconnection fault has occurred. The MCU then issues a disconnection alarm signal.

[0058] When the power MOSFET Q1 control signal is high by default, the MCU periodically samples the potentials of the drain and source of the power MOSFET Q1 at the digital output port through the voltage sampling circuit. This is because the on-resistance R of the power MOSFET Q1... DS With the on signal (on) present, when there is no open circuit fault in the load line, the current flowing through the on-resistance of the power MOSFET Q1 will generate a voltage drop, causing the potentials of the drain and source of the power MOSFET Q1 to be inconsistent. This voltage difference V is amplified by the error amplifier circuit. DS The voltage is compared with a set first reference voltage via a comparator circuit, and a low-level signal is output to the MCU to indicate that there is no open circuit fault. When an open circuit fault occurs in the load line, no current flows through the MOSFET's on-resistance, causing the potentials of the MOSFET's drain (D) and source (S) to be the same, and the voltage difference V between them to be... DS When the value is 0, the subsequent error amplifier circuit outputs a low level, which is compared with the set first reference voltage by the voltage comparator. If the value is less than the set first reference voltage, the comparator outputs a high level signal to feed back to the MCU, indicating that a disconnection fault has occurred. The MCU then issues a disconnection alarm signal.

[0059] To achieve short-circuit detection and protection of the load line, a sampling MOSFET Q2 and a precision sampling resistor R are used. S With the power MOSFET Q1 and load R of the digital output module L Form a current mirror circuit, and interact with the load current I. L The test is performed. Assuming the channel width-to-length ratio of power MOSFET Q1 is (W / L)1, and the channel width-to-length ratio of sampling MOSFET Q2 is (W / L)2, according to the working principle of the current mirror circuit, the load current I... L With the flow through the precision sampling resistor R S Sampling current I S The following relationship must be satisfied:

[0060]

[0061] Precision sampling resistor R S Sampling voltage V at both ends S With the flow through the precision sampling resistor R S Sampling current I S The following relationship must be satisfied:

[0062] V S =I S R S

[0063] The on-resistance of power MOSFET Q1 is R DS(on), when the digital output module is working normally, that is, when the power MOSFET Q1 and the sampling MOSFET Q2 are turned on, the load current I... L The following relationship must be satisfied:

[0064]

[0065] At this time, the flow through the precision sampling resistor R S Sampling current I S The following relationship must be satisfied:

[0066]

[0067] At this time, the precision sampling resistor R S The sampling voltage at both ends is

[0068]

[0069] Set the second reference voltage to

[0070]

[0071] When there is no short-circuit fault in the load line, and power MOSFET Q1 and sampling MOSFET Q2 are normally turned on, that is, the voltage at the source S of power MOSFET Q1 and sampling MOSFET Q2 is 24V, the precision sampling resistor R... S The sampling voltage at both ends is V S As the input signal of the voltage comparator U3 circuit, it is equal to the set second reference voltage. When U3 outputs a low level, Q1 is turned on, and the MCU outputs a control signal to control the power MOSFET Q1 and the sampling MOSFET Q2 to work normally.

[0072] When a short circuit fault occurs in the load line, and power MOSFET Q1 and sampling MOSFET Q2 are normally turned on, that is, the voltage at the source S of power MOSFET Q1 and sampling MOSFET Q2 is 24V, and the load resistance R... L The load current I approaches infinity and is approximately zero. L The short-circuit current tends towards infinity, and the precision sampling resistor R... S Sampling voltage V at both ends S The voltage tends to infinity, which is much greater than the set second reference voltage. U3 outputs a high level, Q1 is turned off, and power MOSFET Q1 and sampling MOSFET Q2 enter the off state without control signal. The digital output stops and enters the short circuit protection state.

[0073] The multi-channel PWM control signals for the digital output of the channels are generated by a high-bit MCU.

[0074] When the power MOSFET Q1 control signal is at a default low level, the disconnection detection module outputs a narrow pulse with a pulse width of 2ms. This narrow pulse signal briefly turns on the power MOSFET Q1. When the digital output module is used to drive inductive loads such as solenoid valves and power relays, the pulse width of the narrow pulse signal can be configured according to the load response time. During the period when the power MOSFET Q1 is turned on by the narrow pulse signal, the potentials of the drain and source of the power MOSFET Q1 at the digital output port are sampled by the voltage sampling circuit. Since the internal resistance R of the power MOSFET Q1 during conduction... ds With the on signal (on) present, when there is no open circuit fault in the load line, the current flowing through the on-resistance of the power MOSFET Q1 will generate a voltage drop, causing the potentials of the drain and source of the power MOSFET Q1 to be inconsistent. This voltage difference V is amplified by the error amplifier circuit. DS The voltage is compared with a set first reference voltage via a comparator circuit, and a low-level signal is output to the MCU to indicate that there is no open circuit fault. When an open circuit fault occurs in the load line, no current flows through the MOSFET's on-resistance, causing the potentials of the MOSFET's drain (D) and source (S) to be the same, and the voltage difference V between them to be... DS When the voltage is 0, the subsequent error amplifier circuit outputs a low level. This low level is compared with a set first reference voltage by a voltage comparator. If the voltage is less than the set first reference voltage, the comparator outputs a high-level signal, which is fed back to the MCU, indicating a disconnection fault. The MCU then issues a disconnection alarm signal. When the power MOSFET Q1 control signal is high by default, the MCU periodically samples the potential of the drain and source of the power MOSFET Q1 at the digital output port through a voltage sampling circuit. Since the on-resistance R of the power MOSFET Q1 is zero... ds With the on signal (on) present, when there is no open circuit fault in the load line, the current flowing through the on-resistance of the power MOSFET Q1 will generate a voltage drop, causing the potentials of the drain and source of the power MOSFET Q1 to be inconsistent. This voltage difference V is amplified by the error amplifier circuit. DS The voltage is compared with a set first reference voltage via a comparator circuit, and a low-level signal is output to the MCU to indicate that there is no open circuit fault. When an open circuit fault occurs in the load line, no current flows through the MOSFET's on-resistance, causing the potentials of the MOSFET's drain (D) and source (S) to be the same, and the voltage difference V between them to be... DS When the value is 0, the subsequent error amplifier circuit outputs a low level, which is compared with the set first reference voltage by the voltage comparator. If the value is less than the set first reference voltage, the comparator outputs a high level signal to feed back to the MCU, indicating that a disconnection fault has occurred. The MCU then issues a disconnection alarm signal.

[0075] The short-circuit detection module samples the load current in the digital output load line through a current mirror circuit and compares it with a set reference voltage through a comparator circuit. The output high or low level controls the switching of the MOSFET control signal transmission channel to achieve short-circuit protection. Specifically, when there is no short-circuit fault in the load line and the power MOSFET Q1 and sampling MOSFET Q2 are normally conducting (i.e., the voltage at the source S of power MOSFET Q1 and sampling MOSFET Q2 is 24V), the precision sampling resistor R... S The sampling voltage at both ends is V SN The input signal to voltage comparator U3 is equal to the set second reference voltage. U3 outputs a low level, Q1 conducts, and the MCU outputs a control signal to control power MOSFET Q1 and sampling MOSFET Q2 to operate normally. When a short circuit fault occurs in the load line, and power MOSFET Q1 and sampling MOSFET Q2 are normally conducting (i.e., the voltage at the source S of power MOSFET Q1 and sampling MOSFET Q2 is 24V), the load resistance R... L The load current I approaches infinity and is approximately zero. L The short-circuit current tends towards infinity, and the precision sampling resistor R... S Sampling voltage V at both ends S The voltage tends to infinity, which is much greater than the set second reference voltage. U3 outputs a high level, Q1 is turned off, the power MOSFET Q1 enters the off state without a control signal, the digital output stops, and it enters the short circuit protection state.

[0076] The first reference voltage and the second reference voltage can be configured by resistor voltage division to achieve any desired preset value. Different preset values ​​of the second reference voltage represent different load current thresholds, which makes it easy to configure different load current thresholds according to different load requirements.

[0077] The above description of the specific embodiments of the present invention is only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made to the present invention by those skilled in the art based on the above description shall fall within the scope of protection of the present invention.

Claims

1. A high-power digital output method for short-circuit detection and protection, characterized in that, This includes the following: The control signal for the digital output of the channel is obtained from the control signal generated by the MCU through the control signal output switch module, which controls the MOSFET. The short-circuit detection module performs short-circuit detection and protection on the load line of the digital output module. When a short circuit occurs, the control signal output switch module turns off the output of the MOSFET control signal, thus shutting off the digital output. The open-circuit detection module performs open-circuit detection on the load line of the digital output module. When an open-circuit fault occurs, it feeds back to the MCU. The MCU controls the alarm device to send an open-circuit alarm signal. When the power MOSFET Q1 control signal is low by default, the open-circuit detection module outputs a narrow pulse to briefly turn on the power MOSFET Q1, amplifying the voltage difference V through the error amplifier circuit. DS V DS The voltage comparator U2 is compared with a set first reference voltage. If the voltage is greater than the first reference voltage, U2 outputs a low-level signal to the MCU, indicating that there is no open circuit fault. DS The voltage difference V is compared with the set first reference voltage by U2. If it is less than the set first reference voltage, U2 outputs a high-level signal to feed back to the MCU, indicating a disconnection fault. When the power MOSFET Q1 control signal is high by default, the voltage difference V is amplified by the error amplifier circuit. DS V DS By comparing U2 with the set first reference voltage, if it is greater than the first reference voltage, U2 outputs a low-level signal to feed back to the MCU, indicating that there is no open circuit fault. DS By comparing U2 with the set first reference voltage, if it is less than the set first reference voltage, U2 outputs a high-level signal to feed back to the MCU, indicating that a disconnection fault has occurred.

2. The high-power digital output method for short-circuit detection and protection according to claim 1, characterized in that, The wire breakage detection includes the following: The control signal for the power MOSFET Q1 is divided into low level and high level; When the control signal for power MOSFET Q1 is low by default, a narrow pulse is output, which briefly turns on power MOSFET Q1. During the conduction period controlled by the narrow pulse, the potentials of the drain and source of power MOSFET Q1 are sampled. After power MOSFET Q1 is turned on, there is an internal resistance R. DS (on); When there is no open circuit fault in the load line, the current flowing through the on-resistance of the power MOSFET Q1 will generate a voltage drop, causing the potentials of the drain and source of the power MOSFET Q1 to be inconsistent. The voltage difference V between the two is amplified by the error amplifier circuit. DS The voltage comparator U2 compares the voltage with the set first reference voltage. If the voltage is greater than the set first reference voltage, the voltage comparator U2 outputs a low-level signal to feed back to the MCU, indicating that there is no open circuit fault. When a break in the load line occurs, no current flows through the on-resistance of the power MOSFET Q1. The drain and source potentials of the power MOSFET Q1 are the same, and the voltage difference between them is V. DS When the value is 0, the subsequent error amplifier circuit outputs a low level, V DS The voltage comparator U2 is compared with the set first reference voltage. If it is less than the set first reference voltage, the voltage comparator U2 outputs a high-level signal to feed back to the MCU, indicating that a disconnection fault has occurred. The MCU then controls the issuance of a disconnection alarm signal. When the control signal for power MOSFET Q1 is high by default, the MCU periodically samples the potentials of the drain and source of power MOSFET Q1. This is because the on-resistance R of power MOSFET Q1... DS With the on signal present, when there is no open circuit fault in the load line, the current flowing through the on-resistance of the power MOSFET Q1 generates a voltage drop, causing the potentials of the drain and source of the power MOSFET Q1 to be inconsistent. This voltage difference V is amplified by the error amplifier circuit. DS The voltage is compared with a set first reference voltage via voltage comparator U2. If the voltage is greater than the set first reference voltage, a low-level signal is output to the MCU, indicating that there is no open circuit fault. When an open circuit fault occurs in the load line, no current flows through the on-resistance of power MOSFET Q1, causing the drain D and source S of power MOSFET Q1 to have the same potential, and the voltage difference V between them is... DS When the value is 0, the subsequent error amplifier circuit outputs a low level, V DS The voltage comparator U2 is compared with the set first reference voltage. If the voltage is less than the set reference voltage, the comparator outputs a high-level signal to the MCU, indicating that a disconnection fault has occurred. The MCU then issues a disconnection alarm signal.

3. The high-power digital output method for short-circuit detection and protection according to claim 1, characterized in that, The short-circuit detection and protection includes the following: The channel width-to-length ratio of power MOSFET Q1 is (W / L)1, and the channel width-to-length ratio of sampling MOSFET Q2 is (W / L)2. According to the working principle of the current mirror circuit, the load current I... L With the flow through the precision sampling resistor R S Sampling current I S The following relationship must be satisfied: Precision sampling resistor R S Sampling voltage V at both ends S With the flow through the precision sampling resistor R S Sampling current I S The following relationship must be satisfied: V S =I S R S The on-resistance of power MOSFET Q1 is R DS (on), when the digital output module is working normally, that is, when the power MOSFET Q1 and the sampling MOSFET Q2 are turned on, the load current I... L The following relationship must be satisfied: At this time, the flow through the precision sampling resistor R S Sampling current I S The following relationship must be satisfied: At this time, the precision sampling resistor R S The sampling voltage at both ends is Set the second reference voltage to K is the control signal; When there is no short-circuit fault in the load line, and power MOSFET Q1 and sampling MOSFET Q2 are normally turned on, that is, the voltage at the source S of power MOSFET Q1 and sampling MOSFET Q2 is 24V, the precision sampling resistor R... S The sampling voltage at both ends is V S As the input signal to voltage comparator U3, equal to the set second reference voltage, voltage comparator U3 outputs a low level, MOSFET Q1 conducts, and the MCU normally outputs a control signal to control power MOSFET Q1 and sampling MOSFET Q2 to work normally; when a short circuit fault occurs in the load line, and power MOSFET Q1 and sampling MOSFET Q2 are normally conducting, that is, when the voltage at the source S of power MOSFET Q1 and sampling MOSFET Q2 is 24V, the load resistance R L The load current I approaches infinity and is approximately zero. L The short-circuit current tends to infinity, and the precision sampling resistor R S Sampling voltage V at both ends S The voltage approaches infinity, which is much greater than the set second reference voltage. The voltage comparator U3 outputs a high level, MOSFET Q1 is turned off, and the power MOSFET Q1 and sampling MOSFET Q2 enter the off state without control signal. The digital output stops and enters the short circuit protection state.

4. A high-power digital output device for short-circuit detection and protection, employing the high-power digital output method for short-circuit detection and protection as described in any one of claims 1-3, characterized in that, It includes the hardware circuitry and the software control section for the control circuitry; The hardware circuit includes an MCU, an alarm device, a switching device, a voltage comparator U2, a voltage comparator U3, several resistors, an error amplifier circuit, and a current mirror circuit. The MCU is connected to the alarm device, the switching device, and the output of the voltage comparator U2. The positive input of the voltage comparator U2 is connected to the first reference voltage through a resistor, and the negative input of the voltage comparator U2 is connected to the error amplifier circuit through a resistor. The switching device is also connected to the current mirror circuit and the output of the voltage comparator U3. The positive input of the voltage comparator U3 is connected to the second reference voltage through a resistor. The current mirror circuit uses MOSFETs, including a power MOSFET Q1 and a sampling MOSFET Q2. The error sampling circuit is connected to the current mirror circuit. The software control section includes an MCU module, which connects to several channels. Each channel includes a short-circuit detection module, a control signal switch module, a disconnection detection module, and a digital output module. The digital output module is used to configure the fault-safe mode and output type settings of the digital signals of the multiple output channels through software. Fail-safe modes include output hold and output according to preset values; output types include pulse width output and status output modes.

5. A high-power digital output device for short-circuit detection and protection according to claim 4, characterized in that, The error amplifier circuit includes a voltage comparator U1, resistors R5, R6, R7, and R8; The output of voltage comparator U1 is connected to one end of resistor R5 and the negative input of voltage comparator U2. The other end of resistor R5 is connected to the negative input of voltage comparator U1 and one end of resistor R6. The other end of resistor R6 is connected to the drain of sampling MOSFET Q2. The positive input of voltage comparator U1 is connected to one end of resistor R7 and one end of resistor R8. The other end of resistor R7 is connected to the source of power MOSFET Q1. The other end of resistor R8 is grounded.

6. A high-power digital output device for short-circuit detection and protection according to claim 4, characterized in that, The current mirror circuit includes a power MOSFET Q1, a sampling MOSFET Q2, and a load resistor R. L and precision sampling resistor R S The gates of power MOSFET Q1 and sampling MOSFET Q2 are connected to the switching devices to transmit control signals, and the source of power MOSFET Q1 is connected to the load resistor R. L One end is connected, with the drain of power MOSFET Q1 connected to the +24V power supply, and the source of sampling MOSFET Q2 connected to the resistor at the negative input of voltage comparator U3 and the precision sampling resistor R. S One end is connected, with a load resistor R. L The other end and the precision sampling resistor R S The other end is grounded.

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