A redundant current output circuit and a redundant current output control method

Abstract

The application provides a redundant current output circuit and a redundant current output control method, comprising: a main card and a backup card, which are connected through a communication link; each card comprises: at least one analog output channel, which is used for generating and outputting a current signal for driving an actuator according to a set value; a back sampling module, which is electrically connected with the analog output channel and is used for collecting an actual output value of the output channel of the card in real time; a redundant communication interface, which is used for exchanging state information and output data with the other card through the communication link; and a redundant control module, which is connected with the back sampling module, the redundant communication interface and the analog output channel respectively, and is used for controlling a redundant output mode between the card and the other card according to a deviation between the actual output value and the set value of the card and state information of the other card obtained through the redundant communication interface.

Description

Technical Field

[0001] This invention belongs to the field of circuit technology, specifically relating to a redundant current output circuit and a redundant current output control method. Background Technology

[0002] The gas turbine control system (TWS) is the "brain" and "nerve center" of the gas turbine, responsible for a series of complex tasks such as unit startup, load regulation, fuel control, and safety protection under harsh operating conditions of high temperature, high pressure, and high speed. During gas turbine operation, the control system needs to precisely drive several key actuators, such as the fuel control valve, inlet guide vane (IGV), and anti-surge valve. These actuators are typically positioned and regulated by 4-20mA current signals; therefore, the accuracy and reliability of the analog output module directly determine the gas turbine's control performance, combustion stability, and emission standards.

[0003] With the development of industrial automation technology, the reliability requirements of modern gas turbine control systems have been raised to an "extreme" level. Any loss or deviation of control signals can lead to unplanned shutdowns, equipment damage, or even safety accidents. Therefore, mainstream control systems generally employ redundancy designs to avoid single points of failure. However, in-depth analysis of existing technologies reveals the following defects and shortcomings in current redundancy schemes: For the analog output (AO) at the actuator end, many systems still use a single output channel or a simple "channel hot standby" switching mode. If the output circuit malfunctions (such as DAC chip failure, operational amplifier damage, or output circuit open circuit), even with precise controller calculations, the analog output (AO) cannot transmit the correct instructions to the fuel valve, directly causing malfunctions or failures of the actuator, posing a direct and fatal threat to the combustion stability and safety of the gas turbine unit. Summary of the Invention

[0004] This invention provides a redundant current output circuit and a redundant current output control method, which can at least solve the problems of high single-point failure risk, inability to achieve disturbance-free switching, and idle backup card resources in related analog output redundancy schemes. The technical solution provided by this invention is as follows: On the one hand, a redundant current output circuit for a gas turbine is provided, comprising: A primary card and a backup card, wherein the primary card and the backup card are connected via a communication link; Each board includes: At least one analog output channel is provided for generating and outputting a current signal to drive the actuator according to a set value. The acquisition module is electrically connected to the analog output channel and is used to acquire the actual output value of the output channel of this board in real time. A redundant communication interface is used to exchange status information and output data with another board through the communication link; A redundancy control module is connected to the data acquisition module, the redundancy communication interface and the analog output channel, respectively. It is used to control the redundancy output mode between this board and another board based on the deviation between the actual output value of this board and the set value, as well as the status information of another board obtained through the redundancy communication interface. The redundant output modes include a primary standby hot standby mode and a current sharing output mode. In the current sharing output mode, the primary card and the standby card output in parallel, and each bears a preset proportion of the load current.

[0005] In one alternative implementation, each board further includes: The fault determination module is used to determine that the current output channel of this board is faulty when the deviation between the actual output value and the set value of this board exceeds a preset threshold and the duration of the deviation exceeds a preset debouncing cycle. In response to the fault signal from the fault determination module, the redundancy control module sends a switching request to another board through the redundancy communication interface and shuts down the analog output channel of this board; at the same time, the other board switches to the master card after receiving the switching request and outputs the full value according to the set value.

[0006] In one optional embodiment, the output terminal of the analog output channel is connected in series with an anti-backflow circuit, the anti-backflow circuit including an ideal diode controller and a power MOSFET, the gate of the power MOSFET being controlled by the redundant control module; When this board is determined to be faulty or switched to standby mode, the redundancy control module shuts down the power MOSFET to physically disconnect the output circuit and prevent fault current from flowing back.

[0007] In an optional implementation, when configured in current sharing output mode, the redundant control module of each board exchanges the actual output value of the board in real time through the redundant communication interface, and adjusts the drive signal of the analog output channel of the board based on the closed-loop feedback of the sampled value, so that the output current difference between the main card and the backup card at the parallel output point is maintained within the preset current sharing error range. Furthermore, when the output channel of one of the boards fails, the other board that is not faulty will automatically adjust the output value to the full set value.

[0008] In one alternative implementation, each board further includes: The digital-to-analog converter module is used to convert digital setpoints from the controller into analog voltage signals; A voltage-to-current conversion module, connected to the digital-to-analog conversion module, is used to convert the analog voltage signal into a corresponding current signal; The sampling module includes a precision sampling resistor, a differential amplifier, and an analog-to-digital converter connected in series in the output circuit. The differential amplifier acquires the voltage across the precision sampling resistor, which is then converted into a digital sampling value by the analog-to-digital converter and sent to the redundant control module.

[0009] In one alternative implementation, each board further includes an isolation module, which is disposed at least between the voltage-to-current conversion section of the analog output channel and the output terminal, and between the redundant communication interface and the internal digital circuitry. The isolation module has an isolation withstand voltage of not less than 1500Vrms, and each analog output channel is isolated from the others.

[0010] In an optional implementation, the redundancy control module is further configured to receive configuration instructions via software tools, the configuration instructions including output signal type configuration, redundancy mode configuration, and primary / backup role designation. The output signal types include 0-20mA, 4-20mA, or 0-5V, 0-10V voltage output; When configured in voltage output mode, the analog output channel bypasses the voltage-to-current conversion module and directly outputs the buffered voltage signal.

[0011] In one optional implementation, the primary card and the backup card may be installed in the same power branch or in racks of different power branches, respectively. The communication link is an RS422 serial communication bus. The master card and the backup card periodically check each other's working status through the RS422 bus using heartbeat packets. When the heartbeat packets are lost more than a preset number, the surviving card automatically switches to the master card.

[0012] On the other hand, a redundant current output control method for a redundant current output circuit is provided, comprising the following steps: In response to receiving the configuration command for the current sharing output mode, the primary card and the backup card establish a data interaction channel through the redundant communication interface; The main card and the backup card each set their respective analog output channels to a target current sharing value, and the target current sharing value is a preset proportion of the total set value. The redundancy control module of each board obtains the actual output value of the other party in real time through the redundant communication interface; The redundancy control module dynamically adjusts the digital-to-analog conversion output of the board based on the first deviation between the actual output value of the board and the target current sharing value, and the second deviation between the actual output value of the other party and the target current sharing value, through a closed-loop negative feedback algorithm, so that the two output currents are equal at the parallel connection point. When one of the boards fails, the other board that is not faulty will automatically adjust the output value to the full set value.

[0013] On the other hand, a redundant current output control method for a redundant current output circuit is provided, comprising the following steps: The main card and the backup card each collect the actual output value of their respective output channels in real time through their respective acquisition modules. Each board exchanges actual output values ​​and health status information with another board through a redundant communication interface; The redundancy control module of each board compares the deviation between the actual output value and the set value of its own board; When the deviation exceeds a preset threshold, the output channel of this board is determined to be faulty. This board sends a switching request to another board through the redundant communication interface and shuts down the output channel of this board. After receiving the switching request, the other board switches to the master board and outputs the full value according to the set value, thereby achieving a seamless switching.

[0014] In one optional implementation, an active fault self-diagnosis step is also included: after the main card and the backup card are powered on, they exchange their respective hardware identification information via the RS422 bus; The hardware identification information is compared, and the card with the smaller identification value is automatically set as the primary card, while the other card is set as the backup card. The main card outputs the full value according to the set value, and the standby card outputs 0mA (hot standby) or outputs according to the current sharing ratio; The primary card periodically sends synchronization data to the backup card, and the backup card maintains the same output parameter configuration as the primary card.

[0015] This invention allows users to flexibly select redundancy strategies based on on-site reliability requirements: current sharing mode is used when extreme reliability is required, avoiding output interruptions caused by single-board failures; hot standby mode is used when simple backup is needed. Simultaneously, through the feature of "parallel output + load sharing," it solves the problem of idle backup card resources in traditional redundancy, achieving load sharing, extending board lifespan, and ensuring the combustion stability and unit safety of the gas turbine. Attached Figure Description

[0016] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A redundant current output circuit architecture diagram for a gas turbine is provided for an embodiment of the present invention.

[0017] Figure 2 The output sub-board circuit architecture diagram provided for embodiments of the present invention.

[0018] Figure 3 A schematic flowchart of the redundant current output control method for the redundant current output circuit provided in the embodiments of the present invention. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0020] The following detailed description is exemplary and intended to provide further detailed explanation of the invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this invention is for describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention.

[0021] Please see Figure 1 and Figure 2 The present invention provides a redundant current output circuit for a gas turbine, comprising: a main card and a backup card, wherein the main card and the backup card are connected by a communication link; Each board includes: At least one analog output channel is provided for generating and outputting a current signal to drive the actuator according to a set value. The data acquisition module is electrically connected to the analog output channel and is used to acquire the actual output value of the output channel of this board in real time. Redundant communication interfaces are used to exchange status information and output data with another board via a communication link; The redundant control module is connected to the data acquisition module, the redundant communication interface and the analog output channel respectively. It is used to control the redundant output mode between this board and another board based on the deviation between the actual output value and the set value of this board, as well as the status information of another board obtained through the redundant communication interface. The redundant output modes include primary standby hot standby mode and current sharing output mode. In current sharing output mode, the primary card and the standby card output in parallel, and each bears a preset proportion of the load current.

[0022] This invention lays the foundation for high-precision, high-reliability current output by defining a primary / backup dual-board architecture and two redundancy modes (hot standby and current sharing). Compared to traditional single-output or simple switching solutions, this invention allows users to flexibly choose redundancy strategies based on field reliability requirements: current sharing mode is used when extreme reliability is required, avoiding output interruptions caused by single-board failures; hot standby mode is used when simple backup is needed. Simultaneously, the "parallel output + load sharing" feature highlights the innovation of the current sharing mode, solving the problem of idle backup card resources in traditional redundancy, achieving load amortization, and extending board lifespan.

[0023] Primary and backup cards: These refer to two circuit boards with identical hardware structures. One is designated as the current primary output device (primary card), and the other serves as the backup output device (backup card). Their roles are interchangeable. Analog output channels refer to the circuit paths that convert digital control signals into continuously varying current signals (e.g., 4-20mA).

[0024] A sampling module is a circuit that measures the actual value of the output current in real time to determine whether the output is accurate.

[0025] Redundancy control module: The logic unit responsible for decision-making on primary / standby switching, current sharing, and fault handling can be implemented collaboratively by a field-programmable gate array (FPGA) and a microcontroller unit (MCU).

[0026] The primary standby hot standby mode means that the primary card outputs full current normally while the standby card is in standby mode (outputting 0mA or extremely low current). Once the primary card fails, the standby card will immediately take over.

[0027] The current sharing output mode means that the main card and the backup card output simultaneously, each bearing half of the total load current (or other preset proportions), and jointly driving the same actuator.

[0028] Parallel output refers to the direct connection of the same numbered output terminals of two boards to the same field device (such as a fuel regulating valve).

[0029] The circuit of this invention consists of two independent boards (primary and backup) connected by a communication link. Each board includes an analog output channel, a sampling module, a redundant communication interface, and a redundant control module. The redundant control module dynamically determines whether the two boards are in primary / backup hot standby mode or current sharing output mode based on the deviation between the actual and set values ​​sampled by the board, and the status information obtained from the other board. In current sharing mode, the two boards output in parallel, each bearing a preset proportion of the load current (e.g., 50% each).

[0030] As an example, a gas turbine control system needs to drive a fuel regulating valve, whose positioner receives a 4-20mA signal. Channel 1 of two boards (board A and board B) of this invention is connected in parallel to the valve. The system is configured in "flow sharing output mode" using software tools, and the output is set to 12mA. At this time, board A outputs 6mA, and board B outputs 6mA, together stabilizing the valve at 50% opening. If board A experiences output drift due to DAC chip aging, the sampling module detects a deviation of 6mA from the actual value. The redundant control module then uses closed-loop adjustment to restore board A to 6mA, ensuring the total output remains 12mA.

[0031] In one alternative implementation, each board further includes: The fault determination module is used to determine that the current output channel of this board is faulty when the deviation between the actual output value and the set value of this board exceeds a preset threshold and the duration of the deviation exceeds a preset debouncing cycle. In response to the fault signal from the fault determination module, the redundancy control module sends a switching request to another board through the redundancy communication interface and shuts down the analog output channel of this board; at the same time, the other board switches to the master card after receiving the switching request and outputs the full value according to the set value.

[0032] The fault diagnosis module continuously monitors the deviation between the actual output value and the set value of this board. Only when the deviation exceeds a preset threshold and the duration of this deviation exceeds a set dejittering cycle (e.g., three consecutive sampling cycles) is the current channel of this board considered to have truly failed, rather than being caused by external transient interference. Once the fault is confirmed, the redundancy control module immediately sends a switchover request to the other board and shuts down the output channel of this board. Upon receiving the request, the other board immediately switches to the master board and outputs at the original set value, thereby taking over the load.

[0033] As an example, during gas turbine operation, the primary card (board A) drives the anti-surge valve. The setpoint is 8mA. Due to a sudden failure of the operational amplifier in board A, the output jumps to 3mA. The sampling module detects a deviation of -5mA (far exceeding the ±0.1mA threshold) for more than 3ms, and the fault diagnosis module confirms the fault. The redundant control module of board A immediately sends a "switch request" to the backup card (board B) via the RS422 standard (Recommended Standard 422, RS422), while simultaneously shutting down its own output. Upon receiving the request, board B switches from hot standby (output 0mA) to primary card within 30ms, outputting 8mA. The anti-surge valve continues to maintain the correct opening, and the unit operates without disturbance.

[0034] This implementation effectively avoids erroneous switching caused by transient factors such as electromagnetic interference, improving the system's anti-interference capability and operational stability. Simultaneously, it clarifies the action sequence of "actively requesting switching and shutting down this channel after fault confirmation," ensuring the determinism and speed of primary / backup switching, achieving true "disruptive switching," and avoiding the risk of a faulty card still outputting incorrect current in traditional solutions.

[0035] In one alternative implementation, the output terminal of the analog output channel is connected in series with an anti-backflow circuit, which includes an ideal diode controller and a power MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), the gate of which is controlled by a redundant control module.

[0036] When this board is determined to be faulty or switched to standby mode, the redundant control module shuts down the power MOSFET to physically disconnect the output circuit and prevent fault current from flowing back.

[0037] A reverse current protection circuit is a protective circuit that prevents current from flowing backward from the output terminal into the internal circuitry of a faulty board. An ideal diode controller is an integrated circuit that controls an external MOSFET to simulate an ideal diode (extremely low forward voltage drop and complete reverse cutoff). A power MOSFET is a metal-oxide-semiconductor field-effect transistor used as a high-speed electronic switch. The gate is the control electrode of the MOSFET, controlled by a redundant control module outputting high or low levels to turn the switch on or off.

[0038] This invention incorporates a backflow prevention circuit in series at the output terminal of the analog output channel. This circuit consists of an ideal diode controller and a power MOSFET. The redundancy control module can directly control the gate of the power MOSFET. When the board is determined to be faulty or configured into standby mode, the redundancy control module will turn off the MOSFET, thereby physically disconnecting the output circuit of this board from the external parallel point. This prevents external current (e.g., current output from another working board) from flowing back into the faulty board, avoiding the escalation of the fault or affecting the output accuracy of the working board.

[0039] As an example, suppose board A fails, and its output terminal may be short-circuited to ground. Without a backflow prevention circuit, the 6mA current output by board B would flow to ground through the short-circuit path of board A, resulting in the actuator not receiving any current. In this solution, once board A is detected as faulty, its power MOSFET immediately turns off, and the output terminal of board A presents a high-impedance state. At this time, the current of board B can only flow to the actuator and will not flow back into board A, ensuring the normal operation of the current sharing mode.

[0040] The embodiments of this invention fundamentally solve the common problems of "circulating current" and "fault propagation" in parallel redundant outputs. Compared with solutions that rely solely on software zeroing, physical disconnection (especially using MOSFETs) has a response speed in the nanosecond to microsecond range, extremely low on-resistance (milliohm level), and multiple switching lifetimes, significantly improving the reliability and safety of the redundant system and ensuring that a single board failure will not bring down the entire output circuit.

[0041] In an optional implementation, when configured in current sharing output mode, the redundant control module of each board exchanges the actual output value of the board in real time through the redundant communication interface, and adjusts the drive signal of the analog output channel of the board based on the feedback of the sampled value (i.e., real-time acquisition of output current value for feedback), so that the output current difference between the main card and the backup card at the parallel output point is maintained within the preset current sharing error range. Furthermore, when the output channel of one of the boards fails, the other board that is not faulty will automatically adjust the output value to the full set value.

[0042] Closed-loop feedback regulation refers to a control method where the system automatically corrects the control quantity based on the error between the actual output and the target, bringing the error close to zero. The drive signal refers to the voltage or digital command that controls the analog output channel to generate a specific current. The preset current sharing error range refers to the maximum allowable difference between the currents of two output channels, such as ±0.5% FS or ±0.1mA.

[0043] Once the user configures the current sharing mode using the software tool, the redundant control modules of each board exchange their actual output values ​​in real time through a redundant communication interface (such as RS422). Then, each board independently adjusts the output of its analog-to-digital converter module using a closed-loop feedback algorithm (such as PI control) based on the deviation between its own actual value and the target current sharing value (such as 50% of the set value), as well as the deviation between the other board's actual value and the target current sharing value, thereby fine-tuning the current of its own board. Ultimately, this ensures that the current difference between the main and backup boards at the parallel output point is controlled within the preset current sharing error range. If one board fails, the other, unaffected board will automatically adjust its output value from 50% to 100% of the set value, ensuring that the total output remains unchanged.

[0044] As an example, the setpoint is 20mA (full scale), and the target for each board in current sharing mode is 10mA. Due to temperature changes, board A actually outputs 10.2mA, while board B actually outputs 9.8mA, a difference of 0.4mA exceeding the allowable error (e.g., 0.1mA). After receiving the 9.8mA data from board B, the redundant control module of board A calculates that its output is 0.2mA too high, and thus slightly reduces the DAC output, bringing board A down to 10.0mA; simultaneously, board B slightly increases the DAC output to 10.0mA. Ultimately, both outputs are 10.0mA, eliminating the error. If board A were to completely fail and output 0 at this point, board B would detect a loss of connection or an abnormal retrieval value, automatically increasing its output from 10mA to 20mA to continue driving the valve.

[0045] This invention achieves load sharing and ensures extremely high output consistency (high-precision parallel connection) by exchanging current data in real time and actively adjusting. When one path fails, the other path can automatically output at full value, realizing "fault tolerance" rather than just "fault switching". This design is particularly suitable for gas turbine actuators with stringent requirements for continuous output, avoiding output jumps caused by a single path failure.

[0046] In one alternative implementation, each board further includes: The digital-to-analog converter module is used to convert digital setpoints from the controller into analog voltage signals; The voltage-to-current conversion module, connected to the digital-to-analog conversion module, is used to convert analog voltage signals into corresponding current signals; The sampling module includes a precision sampling resistor, a differential amplifier, and an analog-to-digital converter connected in series in the output circuit. The differential amplifier acquires the voltage across the precision sampling resistor, which is then converted into a digital sampling value by the analog-to-digital converter and sent to the redundant control module.

[0047] A digital-to-analog converter (DAC) is a chip that converts digital quantities (such as 12-bit or 16-bit binary numbers) into analog voltages. A voltage-to-current converter (V / I converter) is a circuit that linearly converts an input analog voltage into a standard current signal (such as 4-20mA); a common chip is the XTR111. A precision sampling resistor is a resistor with a precise resistance value (e.g., 0.05% tolerance) and extremely low temperature drift, connected in series in the output circuit for current sampling. A differential amplifier is an amplifier that amplifies the voltage difference between two input terminals, used to eliminate common-mode noise and accurately extract the small voltage across the sampling resistor. An analog-to-digital converter (ADC) is a chip that converts analog voltages into digital values.

[0048] First, the digital setpoint from the central controller (e.g., the digital code corresponding to 12mA) is converted into an analog voltage (e.g., 1.2V) by the digital-to-analog converter (DAC). Then, the voltage-to-current converter linearly converts this voltage into the corresponding current (e.g., 12mA). Simultaneously, the sampling module consists of a precision sampling resistor, a differential amplifier, and an analog-to-digital converter (ADC). The output current flows through the precision sampling resistor, generating a voltage drop. The differential amplifier amplifies this voltage drop and sends it to the ADC, which converts it into a digital sampled value and sends it back to the redundant control module (or FPGA), forming a closed loop.

[0049] As an example, the central processing unit (CPU) requests a 16mA output to the inlet adjustable guide vane (IGV). The MCU writes the digital value of "16mA" to the DAC, which outputs 2.0V (assuming 10mA corresponds to 1.25V, linearly). The V / I conversion circuit converts the 2.0V to a 16mA current. This current flows through a 10Ω precision sampling resistor, producing a 160mV voltage drop. The differential amplifier amplifies this by 10 times to obtain 1.6V, which is then sampled by the ADC to obtain the digital value. The redundant control module compares this value with the theoretical digital value corresponding to 16mA; if the error is within the allowable range, the output is considered normal.

[0050] This invention achieves accurate, low-latency, and high-resolution monitoring of the output current through a combination of precision sampling resistors, differential amplifiers, and ADCs, providing a reliable data source for fault diagnosis and closed-loop regulation. This forms the hardware foundation for the entire system to achieve 0.1% full-scale accuracy.

[0051] In one alternative implementation, each board further includes an isolation module, which is disposed at least between the voltage-to-current conversion section of the analog output channel and the output terminal, and between the redundant communication interface and the internal digital circuitry. The isolation module has an isolation withstand voltage of not less than 1500Vrms, and each analog output channel is isolated from the others.

[0052] An isolation module is a circuit that uses optocoupler, magnetic coupling, or capacitor isolation technology to make signals or power supplies electrically independent of each other. Isolation withstand voltage refers to the maximum instantaneous voltage (usually the RMS value at power frequency) that the isolation module can withstand; for example, 1500Vrms means it can withstand 1500 volts of AC voltage for one minute without breakdown. Channel isolation means that the ground and power supply of each analog output channel are independent, so a fault in one channel (such as a short circuit) will not affect other channels.

[0053] This invention specifies that each board includes an isolation module, and the isolation module is located in at least two key locations: first, between the voltage-to-current conversion section of the analog output channel and the output terminal (i.e., on the signal output path); and second, between the redundant communication interface and the internal digital circuitry (to prevent external interference from entering). The isolation withstand voltage is not less than 1500Vrms, meeting the requirements of harsh electromagnetic environments in industrial settings. Furthermore, each analog output channel is also mutually isolated, meaning that each channel has its own independent isolation power supply and signal isolation device.

[0054] As an example, a gas turbine field may experience transient overvoltages of several thousand volts during the startup of a high-power frequency converter. If the circuit board lacks isolation, the overvoltage could be transmitted to the board through the output terminals, potentially damaging the V / I conversion chip or FPGA. In this invention, there is a 1500Vrms isolation between the output terminals and the internal circuitry, preventing transient overvoltages from penetrating. Furthermore, if a terminal of one channel is mistakenly connected to a 220V power supply, only the isolation stage of that channel will be damaged; the other three channels will continue to operate normally, and the digital portion of the circuit board (FPGA / MCU) will remain unaffected.

[0055] This invention significantly improves the anti-interference and fault isolation capabilities of the control board by forcibly implementing high-voltage isolation at signal output and communication interfaces, as well as mutual isolation between channels. This meets the high reliability and high safety requirements of gas turbine control systems, avoids the scrapping of the entire control board due to external wiring problems or single-channel failures, reduces maintenance costs, and improves system availability.

[0056] In an optional implementation, the redundancy control module is further configured to receive configuration instructions via software tools, the configuration instructions including output signal type configuration, redundancy mode configuration, and primary / backup role designation. Output signal types include 0-20mA, 4-20mA, or 0-5V, 0-10V voltage output; When configured in voltage output mode, the analog output channel bypasses the voltage-to-current conversion module and directly outputs the buffered voltage signal.

[0057] The software tool refers to the configuration program running on a host computer (such as an engineering workstation) and interacts with the board through a communication interface. Configuration commands are parameter setting commands issued by the user through the software tool, such as "Output type: 4-20mA", "Redundancy mode: Current sharing", and "Master card: Board A". The bypass voltage-to-current conversion module, when configured for voltage output, bypasses the V / I conversion circuit via an analog switch or relay, directly outputting the DAC output voltage through a buffer amplifier.

[0058] Users can send configuration commands to the board remotely or locally using dedicated software tools. These commands include: output signal type (0-20mA, 4-20mA, or 0-5V, 0-10V voltage), redundancy mode (primary / standby hot standby or current sharing), and primary / standby role assignment (forced assignment or automatic negotiation). Specifically, when configured for voltage output mode, the analog output channel automatically bypasses the voltage-to-current conversion module, instead directly outputting the DAC output voltage signal to the terminals after passing through a buffer amplifier, thus supporting voltage-type actuators.

[0059] As an example, consider an actuator in the field that is voltage-controlled (e.g., 0-10V input). An engineer uses software on a laptop to connect to the board via Ethernet, selects "Channel 1 Output Type" as "0-10V" on the interface, and sets the redundancy mode to "Master / Standby Hot Standby." Upon receiving the command, the board's internal relays activate, bypassing the V / I conversion module and outputting 0-10V. If a 4-20mA change is needed later, only software reconfiguration is required; no hardware replacement is necessary.

[0060] The embodiments of this invention endow the circuit with great flexibility and versatility. Users do not need to replace boards or modify hardware jumpers; they can adapt to different types of actuators (current-type or voltage-type) and different redundancy strategies solely through software, significantly reducing spare parts inventory and field debugging complexity. This "software-defined" analog output capability is not available on traditional fixed-type boards, constituting another innovation of this invention.

[0061] In one alternative implementation, the primary card and the backup card can be installed in the same power branch or in racks of different power branches, respectively. The communication link is an RS422 serial communication bus. The main card and the backup card periodically check each other's working status through the RS422 bus using heartbeat packets. When the number of heartbeat packets lost exceeds a preset number, the surviving card automatically switches to the main card.

[0062] Power branches refer to different power supply areas; for example, branch A is powered by one 24V power supply, and branch B is powered by another independent 24V power supply. A rack refers to the physical slot frame for mounting expansion cards; typically, the backplane provides the bus and power. The RS422 bus is a balanced differential serial communication standard that supports point-to-multipoint communication, has strong anti-interference capabilities, and is suitable for inter-board communication. A heartbeat packet is a periodically sent short message used to indicate whether the expansion card is alive (operating normally).

[0063] This invention allows the primary and backup cards to be flexibly installed in different physical locations: they can be inserted into different slots within the same rack (same power branch), or into racks with different power branches (e.g., one in branch A control cabinet and the other in branch B control cabinet). The two cards communicate via an RS422 serial bus, with communication including heartbeat packets. Each card periodically sends heartbeat packets to the other and listens for the other's heartbeat. If no heartbeat is received from the other for several consecutive times (a preset number, such as 3 times), it is assumed that the other card has failed or communication has been interrupted. In this case, the surviving card will automatically switch to the primary card to ensure uninterrupted output.

[0064] As an example, to improve availability, the user installs board A in "Power Branch 1" of the control cabinet and board B in "Power Branch 2" (powered by different uninterruptible power supplies (UPS)). They are connected via shielded twisted-pair RS422 cable. When the 24V power supply to Branch 1 fails due to a blown fuse, board A stops sending heartbeats. If board B does not receive heartbeats for three consecutive times (approximately 30ms), it determines that board A has failed and automatically switches to master, transitioning from hot standby to full output, while the fuel valve continues to operate normally.

[0065] This invention allows for cross-rack and cross-power supply branch deployment of boards, achieving true physical redundancy and eliminating the risk of single-point failures from a single power supply or backplane bus. Simultaneously, the liveness detection and automatic master / slave switching mechanism based on RS422 (balanced differential serial communication interface) heartbeat eliminates the need for central processing unit involvement, resulting in fast response and high reliability. This flexible deployment capability is not available in existing dedicated redundancy base station solutions, greatly enhancing adaptability to field applications.

[0066] Please see Figure 3 Furthermore, a redundant current output control method for a redundant current output circuit is provided, including: S1. In response to receiving the configuration command for the current sharing output mode, the primary card and the backup card establish a data interaction channel through the redundant communication interface. S2. The main card and the backup card respectively set their respective analog output channels to a target current sharing value, wherein the target current sharing value is a preset ratio of the total set value; S3. The redundancy control module of each board obtains the actual output value of the other party in real time through the redundancy communication interface; S4. The redundancy control module dynamically adjusts the digital-to-analog conversion output of this board based on the first deviation between the actual output value of this board and the target current sharing value, and the second deviation between the actual output value of the other party and the target current sharing value, through a closed-loop negative feedback algorithm, so that the two output currents are equal at the parallel connection point. When one of the boards fails, the other board that is not faulty will automatically adjust the output value to the full set value.

[0067] On the other hand, a redundant current output control method for a redundant current output circuit is provided, comprising the following steps: The main card and the backup card each collect the actual output value of their respective output channels in real time through their respective acquisition modules. Each board exchanges actual output values ​​and health status information with another board through a redundant communication interface; The redundancy control module of each board compares the deviation between the actual output value and the set value of its own board; When the deviation exceeds a preset threshold, the output channel of this board is determined to be faulty. This board sends a switching request to another board through the redundant communication interface and shuts down the output channel of this board. After receiving the switching request, the other board switches to the master board and outputs the full value according to the set value, thereby achieving a seamless switching.

[0068] As an example, during normal operation of the gas turbine, the main card (board A) outputs 12mA to the fuel valve, while the standby card (board B) outputs 0mA in hot standby mode. Suddenly, the V / I conversion chip of board A malfunctions, causing the output to jump to 5mA. The sampling module of board A detects a deviation of -7mA and determines the fault after 3ms. Board A sends a "switch request" via RS422 and then shuts down the output. Upon receiving the request, board B increases the output from 0mA to 12mA within 20ms. The current received by the fuel valve jumps from 5mA to 12mA (but the 5mA only lasts for 23ms; the valve's mechanical response is slow, and its actual position remains almost unchanged), achieving a seamless switching.

[0069] The closed-loop negative feedback algorithm specifically refers to a control logic based on error correction. In this embodiment, the algorithm is executed by the redundant control module (such as an FPGA), and its specific calculation formula is as follows: D out = K p ×( I ref - I fb )+ K i ×( I ref - I fb ).

[0070] in: D out This is the adjustment amount for the digital-to-analog converter (DAC); Iref The target flow equalization value (e.g., 50% of the set value); I fb This refers to the actual output value collected in real time by the data acquisition module. K p This is a proportionality coefficient used to quickly adjust the output based on the current error; K i This is the integral coefficient, used to eliminate static errors and prevent output oscillations.

[0071] The redundant control module periodically (e.g., every 1ms) reads the acquired data. I fb Calculate the error ( Iref Ifb The system updates the DAC's output value according to the formula described above. Through this dynamic adjustment, even if there are slight differences in the component parameters of the two boards, the output current can be forced to match precisely, maintaining the current sharing error within 0.1%.

[0072] As an example, in current sharing mode, the setpoint is 20mA, and the target current sharing value is 10mA. Initially, board A outputs 10.2mA, and board B outputs 9.8mA. After receiving the 9.8mA from B, board A calculates its own deviation +0.2mA and the other party's deviation -0.2mA. Board A's proportional-integral (PI) controller outputs a command to decrease the DAC value, reducing its output to 10.0mA; similarly, board B increases its output to 10.0mA. When board A's MOSFET burns out and short-circuits, its output becomes 0mA. Board B detects that the other party's feedback value is 0 and communication is normal, determining that the other party is faulty. Therefore, it automatically increases its output from 10mA to 20mA, while board A's redundant control module shuts down its MOSFET (if it is not already shut down) to prevent backflow.

[0073] Unlike simple parallel connection, the implementation method of this invention achieves precise current sharing through bidirectional information exchange and independent adjustment, avoiding circulating current and output errors. When one circuit fails, the other circuit seamlessly takes over the entire load, and the total output current remains unchanged. This "current sharing + fault tolerance" design greatly improves the output accuracy and reliability of the system, and is especially suitable for critical actuators in gas turbines that have extremely high requirements for current continuity.

[0074] In one optional implementation, an automatic negotiation step between primary and backup roles is also included: After the primary card and the backup card are powered on, they exchange their respective hardware identification information via the RS422 bus; The hardware identification information of both parties is compared, and the one with the smaller identification value is automatically set as the primary card, while the other is set as the backup card. The main card outputs the full value according to the set value, and the standby card outputs 0mA (hot standby) or outputs according to the current sharing ratio; The primary card periodically sends synchronization data to the backup card, and the backup card maintains the same output parameter configuration as the primary card.

[0075] Hardware identification information: A unique hardware identifier for each board, such as a MAC address, serial number, or programmed ID. Auto-negotiation: Upon power-up, the two cards autonomously determine their primary / backup role via a communication protocol, requiring no manual intervention. Synchronized data: The primary card sends current output parameters, settings, calibration coefficients, etc., to the backup card, ensuring the backup card's hot standby status is consistent with the primary card.

[0076] After the primary and backup cards are powered on, they exchange their respective hardware identification information (such as the last four bits of the MAC address) via the RS422 bus.

[0077] Each board compares its identifier value with another board's identifier value, and the board with the smaller identifier value is automatically designated as the primary board, while the other board is automatically designated as the backup board. If the hardware identifiers are the same (in very rare cases), the power-on time or a random number can be compared further.

[0078] The main card outputs the full value according to the setting value issued by the central processing unit (hot standby mode) or outputs 50% (current sharing mode); the standby card outputs 0mA (hot standby mode) or outputs according to the current sharing ratio.

[0079] The master card periodically sends synchronization data to the backup card, including current settings, output type, calibration parameters, etc., so that the backup card always maintains the same configuration as the master card, so that it can take over at any time.

[0080] As an example, two boards are powered on simultaneously. The last four bits of the MAC address of board A are 0x2A3B, and that of board B is 0x5C8D. After comparison, 0x2A3B < 0x5C8D, so board A automatically becomes the primary board, and board B becomes the backup board. The primary board outputs 12mA, and the backup board outputs 0mA. Every 100ms, the primary board sends synchronization data such as "Set value = 12mA, mode = 4-20mA" to the backup board via RS422. If the primary board is removed, the backup board detects the loss of heartbeat, immediately takes over, and outputs 12mA.

[0081] This invention enables automatic negotiation between primary and backup roles, avoiding configuration errors or conflicts that may arise from manual assignment. Simultaneously, periodic data synchronization ensures that the backup board is always in a "hot standby" state, capable of seamless takeover. This plug-and-play, automatically negotiated redundancy scheme reduces the complexity of on-site debugging and improves system usability and reliability.

[0082] In one optional implementation, an active fault self-diagnosis step is also included: The redundant control module actively fine-tunes the output value of the digital-to-analog conversion module on this board and monitors the change in the actual output value collected by the data acquisition module. If the actual output value does not change with fine-tuning, it is determined that the voltage-to-current conversion module or the sampling module is faulty. If the actual output value is always close to 0 and the digital-to-analog converter module outputs normally, then the output circuit is determined to be open. If the actual output value is much greater than the set value, it is determined that the output is short-circuited to the power supply. Based on different fault types, the redundancy control module generates corresponding fault codes and reports them to the central processing unit through the communication interface.

[0083] Active fault self-diagnosis: Unlike passive detection (which only monitors whether the sampled value matches the set value), active diagnosis refers to the system actively applying a test stimulus (such as fine-tuning the output) and then observing the response to determine whether the internal functional modules are intact. Fine-tuning refers to applying a brief, small increment (e.g., +0.1mA, lasting 1ms) to the normal output value. This change should not cause a response from the actuator, but should be sufficient to be captured by the sampling circuit. Fault codes are numerical codes that identify specific fault types, facilitating rapid problem location by the central processing unit or maintenance personnel.

[0084] The active fault self-diagnosis steps of this invention are as follows: The redundant control module actively makes a small, brief adjustment to the output value of the digital-to-analog converter module on this board (e.g., increasing the full scale by 0.5%). Simultaneously, it monitors whether the actual output value collected by the sampling module changes accordingly with this fine-tuning. The fault type is determined based on the response: If the actual output value does not change with the fine-tuning (or the change is much smaller than expected), it is determined that the voltage-to-current conversion module or the sampling module itself has failed. If the actual output value is consistently close to 0, and the digital-to-analog converter module outputs normally (e.g., the DAC output voltage can be measured), it is determined that there is an open circuit in the output circuit (load disconnection or line breakage). If the actual output value is much larger than the set value (e.g., above full scale), it is determined that the output is short-circuited to the power supply. Based on the identified fault type, the redundant control module generates a corresponding fault code and reports it to the central processing unit via a communication interface (e.g., backplane bus or Ethernet), and optionally illuminates the fault indicator light on the board.

[0085] As an example, when board A is normally outputting 12mA, the redundant control module actively performs self-diagnosis: it fine-tunes the DAC output by +0.1mA (corresponding to a 0.1mA increase in current), and then reads the sampled ADC (Analog-to-Digital Converter) value. If the sampled value also increases by approximately 0.1mA, it indicates that the V / I conversion and sampling channel are normal. If the sampled value remains unchanged, it indicates a V / I conversion or sampling fault. If the sampled value is consistently 0, it indicates an open circuit in the output loop. After the diagnosis is complete, the original output value is restored. The diagnosis cycle can be set to once every 10 seconds without affecting normal control.

[0086] This invention introduces an online self-diagnostic technology that "actively applies disturbances and observes the response," which is impossible with traditional passive diagnosis that "only compares setpoints and sampled values." Active diagnosis can distinguish between "real output faults" and "problems with the setpoint itself," and can pinpoint specific faulty components (DAC, V / I, sampling, load). This deep self-diagnostic capability greatly improves the system's maintainability and fault prediction capabilities, enabling early warnings to be issued before a fault leads to control failure, meeting the high requirements of predictive maintenance in gas turbine control systems.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A redundant current output circuit for a gas turbine, characterized in that, include: A primary card and a backup card, wherein the primary card and the backup card are connected via a communication link; Each board includes: At least one analog output channel is provided for generating and outputting a current signal to drive the actuator according to a set value. The acquisition module is electrically connected to the analog output channel and is used to acquire the actual output value of the output channel of this board in real time. A redundant communication interface is used to exchange status information and output data with another board through the communication link; A redundancy control module is connected to the data acquisition module, the redundancy communication interface and the analog output channel, respectively. It is used to control the redundancy output mode between this board and another board based on the deviation between the actual output value of this board and the set value, as well as the status information of another board obtained through the redundancy communication interface. The redundant output modes include a primary standby hot standby mode and a current sharing output mode. In the current sharing output mode, the primary card and the standby card output in parallel, and each bears a preset proportion of the load current.

2. The redundant current output circuit according to claim 1, characterized in that, Each board also includes: The fault determination module is used to determine that the current output channel of this board is faulty when the deviation between the actual output value and the set value of this board exceeds a preset threshold and the duration of the deviation exceeds a preset debouncing cycle. In response to the fault signal from the fault determination module, the redundancy control module sends a switching request to another board through the redundancy communication interface and shuts down the analog output channel of this board; at the same time, the other board switches to the master card after receiving the switching request and outputs the full value according to the set value.

3. The redundant current output circuit according to claim 2, characterized in that, The output terminal of the analog output channel is connected in series with an anti-backflow circuit, which includes an ideal diode controller and a power MOSFET. The gate of the power MOSFET is controlled by the redundant control module. When this board is determined to be faulty or switched to standby mode, the redundancy control module shuts down the power MOSFET to physically disconnect the output circuit and prevent fault current from flowing back.

4. The redundant current output circuit according to claim 1, characterized in that, When configured in current sharing output mode, the redundant control module of each board exchanges the actual output value of the board in real time through the redundant communication interface, and adjusts the drive signal of the analog output channel of the board based on the closed-loop feedback of the sampled value, so that the output current difference between the main card and the backup card at the parallel output point is maintained within the preset current sharing error range. Furthermore, when the output channel of one of the boards fails, the other board that is not faulty will automatically adjust the output value to the full set value.

5. The redundant current output circuit according to claim 1, characterized in that, Each board also includes: The digital-to-analog converter module is used to convert digital setpoints from the controller into analog voltage signals; A voltage-to-current conversion module, connected to the digital-to-analog conversion module, is used to convert the analog voltage signal into a corresponding current signal; The sampling module includes a precision sampling resistor, a differential amplifier, and an analog-to-digital converter connected in series in the output circuit. The differential amplifier acquires the voltage across the precision sampling resistor, which is then converted into a digital sampling value by the analog-to-digital converter and sent to the redundant control module.

6. The redundant current output circuit according to claim 1, characterized in that, Each board also includes an isolation module, which is at least located between the voltage-to-current conversion section of the analog output channel and the output terminal, and between the redundant communication interface and the internal digital circuitry. The isolation module has an isolation withstand voltage of not less than 1500Vrms, and each analog output channel is isolated from the others.

7. The redundant current output circuit according to claim 1, characterized in that, The redundancy control module is also configured to receive configuration instructions via software tools, the configuration instructions including output signal type configuration, redundancy mode configuration, and primary / backup role designation. The output signal types include 0-20mA and 4-20mA current output or 0-5V and 0-10V voltage output; When configured in voltage output mode, the analog output channel bypasses the voltage-to-current conversion module and directly outputs the buffered voltage signal.

8. The redundant current output circuit according to claim 1, characterized in that, The primary card and the backup card can be installed in the same power branch or in racks of different power branches, respectively; The communication link is an RS422 serial communication bus. The master card and the backup card periodically check each other's working status through the RS422 bus using heartbeat packets. When the heartbeat packets are lost more than a preset number, the surviving card automatically switches to the master card.

9. A method for controlling the redundant current output of a redundant current output circuit, characterized in that, Includes the following steps: In response to receiving the configuration command for the current sharing output mode, the primary card and the backup card establish a data interaction channel through the redundant communication interface; The main card and the backup card each set their respective analog output channels to a target current sharing value, and the target current sharing value is a preset proportion of the total set value. The redundancy control module of each board obtains the actual output value of the other party in real time through the redundant communication interface; The redundancy control module dynamically adjusts the digital-to-analog conversion output of the board based on the first deviation between the actual output value of the board and the target current sharing value, and the second deviation between the actual output value of the other party and the target current sharing value, through a closed-loop negative feedback algorithm, so that the two output currents are equal at the parallel connection point. When one of the boards fails, the other board that is not faulty will automatically adjust the output value to the full set value.

10. A method for controlling the redundant current output of a redundant current output circuit, characterized in that, Includes the following steps: The main card and the backup card each collect the actual output value of their respective output channels in real time through their respective acquisition modules. Each board exchanges actual output values ​​and health status information with another board through a redundant communication interface; The redundancy control module of each board compares the deviation between the actual output value and the set value of its own board; When the deviation exceeds a preset threshold, the output channel of this board is determined to be faulty. This board sends a switching request to another board through the redundant communication interface and shuts down the output channel of this board. After receiving the switching request, the other board switches to the master board and outputs the full value according to the set value, thereby achieving a seamless switching.

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