Plasma knife energy control method and system based on current distortion feedback

Abstract

The application discloses a plasma knife energy control method and system based on current distortion feedback, and relates to the technical field of plasma knife energy control.The application synchronously collects an output current instantaneous value, a root mean square value and an output voltage root mean square value, calculates a current distortion index and automatically identifies a load working stage; a constant voltage control strategy is adopted in a water heating stage, and a double closed loop feedback control strategy based on current distortion is adopted in a plasma stage.The application solves the problem that the output voltage of an existing commercial plasma knife energy generator cannot be adjusted, can flexibly adjust the output voltage in the cutting stage according to the biological tissue type while stabilizing the plasma excitation, effectively reduces the excessive thermal damage of the tissue, reduces the generation of bubbles, and significantly improves the cutting quality of the biological tissue.

Description

Technical Field

[0001] This invention relates to the field of plasma knife energy control technology, and in particular to a plasma knife energy control method and system based on current distortion feedback. Background Technology

[0002] Plasma scalpels rely on applying a specific alternating voltage to generate plasma from saline ions, thereby cutting biological tissues. From activation to tissue cutting, the plasma scalpel undergoes two sequential operating stages: the "water heating stage" and the "plasma stage." In the water heating stage, the energy generator needs to output a high voltage to excite the plasma; only after entering the plasma stage can the plasma scalpel effectively cut biological tissues.

[0003] Existing commercial plasma scalpel energy generators generally suffer from the following drawbacks: They maintain a fixed output voltage during the water heating phase and, even after entering the plasma phase, the output voltage remains consistent with the water heating phase and cannot be adjusted. However, different types of biological tissues have different electrical characteristics and cutting requirements, necessitating flexible adjustment of the output voltage to achieve optimal cutting results. Excessive output voltage leads to overheating of the biological tissue, generating numerous bubbles in the brine that obstruct the operator's view and cause excessive thermal damage to the tissue; conversely, insufficient output voltage prevents successful cutting. Because existing commercial plasma generators cannot adjust the output voltage according to actual cutting conditions, they fail to meet the cutting needs of different biological tissues, severely reducing the cutting quality. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention aims to provide a plasma knife energy control method and system based on current distortion feedback, which can automatically identify the working stage of the plasma knife and adopt different control strategies at different stages to achieve adaptive adjustment of the output voltage in the plasma stage, thereby improving the cutting quality of biological tissues and reducing tissue thermal damage.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A plasma knife energy control method based on current distortion feedback includes the following steps:

[0007] S1 synchronously acquires the instantaneous value of the output current, the root mean square value of the output current, and the root mean square value of the output voltage of the main circuit of the plasma knife energy generator through the sampling circuit, and transmits all the acquired electrical signals to the processor for further processing.

[0008] S2, the processor calculates the peak-to-peak value of the current for each switching cycle based on the received instantaneous value of the output current, obtains the average peak-to-peak value of the current through a sliding window averaging algorithm, and then calculates the current distortion index by combining it with the root mean square value of the output current.

[0009] S3, compare the calculated current distortion index with the system's preset threshold, and automatically identify the current load working stage of the plasma knife based on the comparison result;

[0010] S4. Execute the corresponding energy control strategy according to the identified load operating stage. When the stage is identified as water heating, a constant voltage control strategy is adopted. When the stage is identified as plasma, a dual closed-loop feedback control strategy based on current distortion is adopted.

[0011] Preferably, step S1 specifically includes:

[0012] The instantaneous value of the output current is acquired through a current operational amplifier circuit;

[0013] The root mean square value of the output current is acquired through a current root mean square to DC conversion circuit.

[0014] The root mean square value of the output voltage is acquired through a voltage operational amplifier circuit and a voltage root mean square to DC conversion circuit.

[0015] Preferably, the formula for calculating the sliding window average of the current peak-to-peak values ​​over N consecutive switching cycles in step S2 is as follows:

[0016]

[0017] in, The peak-to-peak current value is the average of N sliding windows. is the peak-to-peak current value during the i-th switching cycle, and N is the size of the sliding window.

[0018] Preferably, the formula for calculating the current distortion index in step S2 is:

[0019]

[0020] in, As an index of current distortion, This represents the average peak-to-peak current. This is the root mean square value of the output current.

[0021] Preferably, step S3 specifically includes:

[0022] When the current distortion index exceeds the preset threshold, the load is determined to be in the plasma stage;

[0023] When the current distortion index is less than or equal to the preset threshold, it is determined that the load is in the water heating stage;

[0024] The preset threshold is a fixed value pre-set by the system.

[0025] Preferably, the constant voltage control strategy in step S4 specifically includes:

[0026] The actual output voltage root mean square value is compared with the preset reference output voltage root mean square value to obtain the voltage deviation value;

[0027] The voltage deviation value is input into the proportional-integral controller to generate a control signal, which is then sent to the main circuit to control the main circuit to output a constant voltage.

[0028] Preferably, the dual closed-loop feedback control strategy based on current distortion in step S4 specifically includes:

[0029] The calculated actual current distortion index is compared with the preset reference current distortion index to obtain the distortion deviation value;

[0030] The distortion deviation value is input into the first proportional-integral controller to generate the reference root mean square value of the output voltage.

[0031] The voltage deviation value is obtained by comparing the reference root mean square value of the output voltage with the actual root mean square value of the actual output voltage.

[0032] The voltage deviation value is input into the second proportional-integral controller to generate a control signal and send it to the main circuit to adjust the actual output voltage of the main circuit.

[0033] Preferably, in step S4, during the entire plasma knife operation process, the processor continuously executes steps S1 to S4 in a loop, monitors the load status changes in real time, and dynamically adjusts the output voltage.

[0034] A plasma knife energy control system based on current distortion feedback includes a main circuit, a sampling circuit, and a processor;

[0035] The sampling circuit is connected to the main circuit and the processor respectively, and is used to collect the instantaneous value of the output current, the root mean square value of the output current and the root mean square value of the output voltage of the main circuit, and send the collected signals to the processor.

[0036] The processor is connected to the main circuit and is used to execute the plasma knife energy control method based on current distortion feedback, generate control signals and send them to the main circuit to control the output of the main circuit.

[0037] Preferably, the sampling circuit includes a current sampling unit and a voltage sampling unit;

[0038] The current sampling unit includes a current operational amplifier circuit and a current root mean square to DC conversion circuit. The input terminal of the current operational amplifier circuit is connected to the output terminal of the main circuit. The first output terminal of the current operational amplifier circuit is directly connected to the first input terminal of the processor and is used to transmit the instantaneous value of the output current to the processor. The second output terminal of the current operational amplifier circuit is connected to the input terminal of the current root mean square to DC conversion circuit. The output terminal of the current root mean square to DC conversion circuit is connected to the second input terminal of the processor and is used to transmit the root mean square value of the output current to the processor.

[0039] The voltage sampling unit includes a voltage operational amplifier circuit and a voltage root mean square to DC conversion circuit. The input terminal of the voltage operational amplifier circuit is connected to the output terminal of the main circuit, the output terminal of the voltage operational amplifier circuit is connected to the input terminal of the voltage root mean square to DC conversion circuit, and the output terminal of the voltage root mean square to DC conversion circuit is connected to the third input terminal of the processor, which is used to transmit the root mean square value of the output voltage to the processor.

[0040] The processor can be any one of a microcontroller, digital signal processor, complex programmable logic device, or field-programmable gate array.

[0041] Compared with the prior art, the beneficial effects of the present invention are:

[0042] This invention accurately identifies the two working stages of the plasma knife by monitoring the output current status. It adopts a hybrid control mode of "constant voltage output - constant current distortion output" to ensure stable plasma excitation during the water heating stage and achieve adaptive regulation of the output voltage during the plasma stage, thus solving the problem that the output voltage of existing generators is not adjustable throughout the entire process.

[0043] This invention innovatively proposes a current distortion index as a measure of the intensity of plasma discharge. By controlling the degree of current distortion, the discharge intensity can be indirectly controlled, enabling the output energy to be automatically adjusted according to the type of biological tissue, effectively improving the cutting quality, while reducing bubble generation and excessive thermal damage to tissue.

[0044] The voltage and current hybrid sampling circuit designed in this invention can simultaneously acquire instantaneous current values ​​and root mean square values, providing more detection information and control degrees of freedom for the control strategy; the state recognition method based on load characteristic differences has high accuracy and fast response speed, providing a reliable foundation for staged control. Attached Figure Description

[0045] Figure 1 This is an architecture diagram of the plasma knife energy control system based on current distortion feedback of the present invention;

[0046] Figure 2 This is an overall flowchart of the plasma knife energy control method based on current distortion feedback according to the present invention. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0048] Example 1

[0049] This embodiment provides a plasma knife energy control method based on current distortion feedback, the overall process of which is as follows: Figure 2 As shown, this method synchronously acquires multi-dimensional electrical signals, calculates current distortion index and identifies load state, and then executes corresponding control strategies according to different stages to achieve adaptive adjustment of plasma knife energy.

[0050] Step S1, synchronous acquisition of electrical signals:

[0051] First, the instantaneous output current, root mean square (RMS) value of the output current, and RMS value of the output voltage of the plasma knife energy generator main circuit are simultaneously acquired via a sampling circuit. All acquired electrical signals are then transmitted to the processor for further processing. This step employs synchronous acquisition to ensure that the three electrical signals are acquired at the same time, avoiding errors in subsequent calculations due to time differences. The specific acquisition process is as follows:

[0052] Output current instantaneous value acquisition: The weak current signal output by the main circuit is linearly amplified by the current operational amplifier circuit. The amplified signal can be directly recognized by the analog-to-digital conversion interface of the processor. The current operational amplifier circuit directly transmits the amplified instantaneous current signal to the processor for subsequent calculation of the peak-to-peak value of the current.

[0053] Output current RMS value acquisition: The current signal output by the current operational amplifier circuit is simultaneously input to the current RMS-DC converter circuit. This circuit can perform real-time RMS value calculation on the input AC current signal and output the calculated DC voltage signal to the processor. The magnitude of the DC voltage signal is proportional to the RMS value of the output current.

[0054] Output voltage root mean square value acquisition: The high-voltage AC voltage signal output by the main circuit is stepped down and linearly amplified by the voltage operational amplifier circuit, and converted into a low-voltage signal that the processor can recognize. Then, the amplified voltage signal is input to the voltage root mean square to DC converter (RMS-DC) circuit, which calculates the root mean square value of the output voltage and transmits the corresponding DC voltage signal to the processor.

[0055] Step S2, Calculation of current distortion index:

[0056] After receiving the acquired electrical signal, the processor calculates the current distortion index based on the instantaneous value and root mean square value of the output current. This step uses a sliding window averaging algorithm to smooth the peak-to-peak value of the current, effectively suppressing the influence of circuit noise and interference on the calculation results and improving the accuracy and stability of the current distortion index. The specific calculation process is as follows:

[0057] First, in each main circuit operating switching cycle Within the cycle, the processor continuously samples the input instantaneous current signal, counts the maximum and minimum values ​​of the instantaneous current within that cycle, and calculates the peak-to-peak current value for that cycle. ,in The sequence number is the switching cycle number, starting from 1 and increasing sequentially.

[0058] To improve the stability and anti-interference capability of the current peak-to-peak value, a sliding window averaging calculation is performed on the current peak-to-peak value over N consecutive switching cycles to obtain the average current peak-to-peak value. The formula for calculating the sliding window average is:

[0059]

[0060] in, The size of the sliding window can be adjusted according to the response speed and anti-interference requirements of the actual system, and is usually in the range of 5-20. When a new switching cycle ends and a new peak-to-peak current value is calculated, the sliding window slides forward one cycle, discards the earliest peak-to-peak current value, adds the latest peak-to-peak current value, and recalculates the average peak-to-peak current value.

[0061] Then, based on the calculated average peak-to-peak current... and the collected root mean square value of output current Calculate the current distortion index The formula for calculating the current distortion index is:

[0062]

[0063] Current distortion index This reflects the degree of distortion of the output current waveform relative to a standard sine wave. For an ideal sinusoidal current, the ratio of its peak-to-peak value to its root mean square value is... Therefore, under ideal conditions, the current distortion index When the current waveform is distorted, this ratio will deviate. This leads to current distortion index Greater than 1. The more severe the current distortion, the better. The larger the value, the better.

[0064] Step S3, Identification of the workload phase:

[0065] The calculated current distortion index is compared with a system-preset threshold, and the current load operating stage of the plasma cutter is automatically identified based on the comparison result. This step identifies the status based on the differences in load characteristics at different operating stages of the plasma cutter, resulting in high accuracy and fast response. The specific judgment rules are as follows:

[0066] when At that time, it is determined that the load is in the plasma stage;

[0067] when At that time, it is determined that the load is in the water heating stage.

[0068] Preset threshold The system's pre-set fixed values ​​can be obtained through experimental calibration. The calibration principle is based on the differences in load characteristics at different operating stages of the plasma knife: during the water heating stage, the plasma knife is in direct contact with the brine, the load is a linear resistive load, and the output current waveform is close to a standard sine wave, with minimal current distortion; therefore, the current distortion index is relatively low. Approaching 1; In the plasma stage, a sufficiently high output voltage enables plasma to be generated between the brine and the plasma blade. The plasma load is a nonlinear load, causing severe distortion of the output current waveform; therefore, the current distortion index... It will be significantly greater than 1. A suitable threshold can be determined by measuring the current distortion index at different operating stages through numerous experiments. The value usually ranges from 1.2 to 1.5.

[0069] Step S4, phased energy control:

[0070] Based on the identified load operating stage, the corresponding energy control strategy is executed. When the stage is identified as water heating, a constant voltage control strategy is adopted; when the stage is identified as plasma, a dual closed-loop feedback control strategy based on current distortion is adopted. Throughout the entire plasma scalpel operation, the processor continuously executes steps S1 to S4 in a loop, monitoring changes in the load state in real time and dynamically adjusting the output voltage to ensure that the plasma scalpel always operates in the optimal state.

[0071] Constant voltage control during water heating stage:

[0072] When the processor detects that the load is in the water heating stage, it employs a constant voltage control strategy to control the output of the energy generator. The goal of this control strategy is to ensure a stable preset voltage output from the main circuit, guaranteeing rapid and stable plasma excitation. The specific control process is as follows:

[0073] The processor will collect the actual root mean square value of the output voltage. Compared with the preset reference output voltage root mean square value By comparison, the voltage deviation value is calculated. .

[0074] Voltage deviation value The input is a proportional-integral (PI) controller. The PI controller calculates and generates a control signal based on the magnitude and trend of the deviation, and sends this control signal to the main circuit. The main circuit adjusts the duty cycle of its power switch according to the received control signal, thereby adjusting the output voltage so that the actual root mean square (RMS) value of the output voltage tracks the preset reference RMS value, achieving a constant voltage output.

[0075] Preset reference output voltage root mean square value The preset value for the system is usually set to 400V-600V. This voltage range can ensure stable plasma excitation under different salt water concentrations and ambient temperatures.

[0076] Dual closed-loop feedback control in the plasma stage:

[0077] When the processor identifies the load as being in the plasma stage, it employs a dual-closed-loop feedback control strategy based on current distortion to control the energy generator's output. This control strategy uses a dual-closed-loop structure, with the outer loop controlling the current distortion and the inner loop controlling the output voltage. This allows for dynamic adjustment of the output voltage based on changes in the biological tissue type, maintaining the plasma discharge intensity at a preset optimal level. The specific control process is as follows:

[0078] First, the processor will calculate the actual current distortion index. Distortion index of preset reference current By comparison, the distortion deviation value is calculated. .

[0079] distortion deviation value The input is a first proportional-integral (PI) controller, which calculates and generates the reference root mean square value of the output voltage based on the deviation value. The reference voltage value will be dynamically adjusted according to the changes in the actual current distortion index. When the actual current distortion index is greater than the reference value, the output voltage reference value will be reduced; when the actual current distortion index is less than the reference value, the output voltage reference value will be increased.

[0080] Then, the generated output voltage is referenced to the root mean square value. Compared with the actual root mean square value of the output voltage. By comparison, the voltage deviation value is calculated. .

[0081] Voltage deviation value The input is a second proportional-integral (PI) controller, which calculates and generates a control signal based on the deviation value and sends this control signal to the main circuit. The main circuit adjusts the duty cycle of its power switch according to the received control signal, thereby adjusting the actual output voltage so that the actual current distortion index tracks the preset reference current distortion index.

[0082] Preset reference current distortion index The preset values ​​for the system can be adjusted according to the cutting requirements of different biological tissues. By setting different reference current distortion indices, the intensity of plasma discharge can be controlled, thereby obtaining different cutting effects and degrees of thermal damage. For tissues requiring precise cutting and low thermal damage, a smaller reference current distortion index can be set; for tissues requiring rapid cutting, a larger reference current distortion index can be set.

[0083] Example 2

[0084] This embodiment provides a plasma knife energy control system based on current distortion feedback, used to implement the control method described in Embodiment 1. The overall architecture of the system is as follows: Figure 1 As shown, it mainly consists of three parts: the main circuit, the sampling circuit, and the processor. The signal transmission and control are achieved through electrical connections between the parts.

[0085] Main circuit:

[0086] The main circuit is the power conversion circuit of the plasma knife energy generator, responsible for converting the input AC voltage into the high-frequency AC voltage required for the plasma knife to operate. The main circuit typically employs a full-bridge inverter topology, consisting of four power switching transistors. By controlling the on / off sequence of these four transistors, the input DC voltage is inverted into a high-frequency AC voltage output to the plasma knife. The output voltage of the main circuit can be adjusted by changing the duty cycle of the power switching transistors; a higher duty cycle results in a higher output voltage, and a lower duty cycle results in a lower output voltage.

[0087] Sampling circuit:

[0088] The sampling circuit is used to acquire the instantaneous value of the output current, the root mean square value of the output current, and the root mean square value of the output voltage of the main circuit, and sends the acquired signals to the processor. The sampling circuit consists of two parts: a current sampling unit and a voltage sampling unit, which respectively acquire and process the current signal and the voltage signal.

[0089] The current sampling unit includes a current operational amplifier circuit and a root mean square to direct current (RMS-DC) converter circuit. The input of the current operational amplifier circuit is connected to the output of the main circuit, amplifying the current signal output by the main circuit. The current operational amplifier circuit has two outputs: the first output is directly connected to the first input of the processor, transmitting the instantaneous value of the output current to the processor; the second output is connected to the input of the RMS-DC converter circuit. The RMS-DC converter circuit calculates the root mean square (RMS) value of the output current, and its output is connected to the second input of the processor, transmitting the RMS value of the output current to the processor.

[0090] The voltage sampling unit includes a voltage operational amplifier circuit and a root mean square to direct current (RMS-DC) converter circuit. The input of the operational amplifier circuit is connected to the output of the main circuit, used to step down and amplify the voltage signal output by the main circuit. The output of the operational amplifier circuit is connected to the input of the RMS-DC converter circuit. The RMS-DC converter circuit calculates the root mean square (RMS) value of the output voltage, and its output is connected to the third input of the processor to transmit the RMS value of the output voltage to the processor.

[0091] processor:

[0092] The processor is the core of the entire control system. It is responsible for receiving the electrical signals collected by the sampling circuit, executing the plasma knife energy control method based on current distortion feedback as described in Example 1, generating control signals and sending them to the main circuit to control the output of the main circuit.

[0093] The processor can be any one of a microcontroller (STM32), a digital signal processor (DSP), a complex programmable logic device (CPLD), or a field-programmable gate array (FPGA). In this embodiment, a microcontroller (STM32) is preferably used as the processor, which has advantages such as low cost, high performance, rich peripherals, and short development cycle, and can meet the control requirements of this invention.

[0094] The processor integrates a multiplexed analog-to-digital converter (ADC) to convert the analog signals output from the sampling circuit into digital signals for subsequent calculations and processing. It also integrates a multiplexed pulse-width modulation (PWM) output module to generate PWM control signals for the four power switches in the main circuit.

[0095] System working process:

[0096] The complete working process of the plasma knife energy control system based on current distortion feedback described in this invention is as follows:

[0097] After the system is powered on, the main circuit starts to output the initial voltage. At the same time, the sampling circuit starts to collect the instantaneous value of the output current, the root mean square value of the output current, and the root mean square value of the output voltage of the main circuit, and converts these analog signals into voltage signals that the processor can recognize and sends them to the processor.

[0098] The analog-to-digital converter inside the processor converts the received analog signal into a digital signal. Then, based on the received instantaneous digital signal of the output current, it calculates the peak-to-peak current of each main circuit operating switching cycle and performs a sliding window averaging of the peak-to-peak current over N consecutive switching cycles to obtain the average peak-to-peak current.

[0099] The processor calculates the current distortion index according to a preset formula based on the calculated average peak-to-peak value of the current and the acquired root mean square value of the output current digital signal.

[0100] The processor compares the calculated current distortion index with the system's preset threshold and identifies the current working stage of the load based on the comparison result.

[0101] If the system is identified as being in the water heating stage, the processor switches to constant voltage control mode, compares the actual output voltage root mean square value with the preset reference output voltage root mean square value, calculates the voltage deviation value, generates a PWM control signal through a proportional-integral (PI) controller, and sends it to the main circuit to control the main circuit to output a constant voltage in order to quickly excite the plasma.

[0102] When the current distortion index exceeds a preset threshold, the processor recognizes that the load has entered the plasma stage and automatically switches to a dual closed-loop feedback control mode based on current distortion. The processor compares the actual current distortion index with a preset reference current distortion index to calculate the distortion deviation value. This deviation is then used by the first proportional-integral (PI) controller to generate a reference root-mean-square (RMS) value for the output voltage. Next, the processor compares the reference RMS value with the actual RMS value of the output voltage to calculate the voltage deviation value. This deviation is then used by the second PI controller to generate a PWM control signal, which is sent to the main circuit to dynamically adjust the output voltage of the main circuit, ensuring that the actual current distortion index tracks the preset reference current distortion index.

[0103] Throughout the plasma phase, the processor continuously cycles through the above steps, monitors changes in current distortion in real time, and adjusts the output voltage accordingly to adapt to the cutting requirements of different types of biological tissues, ensuring optimal cutting results while reducing bubble generation and excessive thermal damage to tissues.

[0104] The embodiments described above are merely examples of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application.

Claims

1. A plasma knife energy control method based on current distortion feedback, characterized in that, Includes the following steps: S1 synchronously acquires the instantaneous value of the output current, the root mean square value of the output current, and the root mean square value of the output voltage of the main circuit of the plasma knife energy generator through the sampling circuit, and transmits all the acquired electrical signals to the processor for further processing. S2, the processor calculates the peak-to-peak value of the current for each switching cycle based on the received instantaneous value of the output current, obtains the average peak-to-peak value of the current through a sliding window averaging algorithm, and then calculates the current distortion index by combining it with the root mean square value of the output current. S3, compare the calculated current distortion index with the system's preset threshold, and automatically identify the current load working stage of the plasma knife based on the comparison result; S4. Execute the corresponding energy control strategy according to the identified load operating stage. When the stage is identified as water heating, a constant voltage control strategy is adopted. When the stage is identified as plasma, a dual closed-loop feedback control strategy based on current distortion is adopted.

2. The plasma knife energy control method based on current distortion feedback according to claim 1, characterized in that, Step S1 specifically includes: The instantaneous value of the output current is acquired through a current operational amplifier circuit; The root mean square value of the output current is acquired through a current root mean square to DC conversion circuit. The root mean square value of the output voltage is acquired through a voltage operational amplifier circuit and a voltage root mean square to DC conversion circuit.

3. The plasma knife energy control method based on current distortion feedback according to claim 1, characterized in that, The formula for calculating the sliding window average of the current peak-to-peak values ​​over N consecutive switching cycles in step S2 is as follows: in, The peak-to-peak current value is the average of N sliding windows. is the peak-to-peak current value during the i-th switching cycle, and N is the size of the sliding window.

4. The plasma knife energy control method based on current distortion feedback according to claim 1, characterized in that, The formula for calculating the current distortion index in step S2 is as follows: in, As an index of current distortion, This represents the average peak-to-peak current. This is the root mean square value of the output current.

5. The plasma knife energy control method based on current distortion feedback according to claim 1, characterized in that, Step S3 specifically includes: When the current distortion index exceeds the preset threshold, the load is determined to be in the plasma stage; When the current distortion index is less than or equal to the preset threshold, it is determined that the load is in the water heating stage; The preset threshold is a fixed value pre-set by the system.

6. The plasma knife energy control method based on current distortion feedback according to claim 1, characterized in that, The constant voltage control strategy in step S4 specifically includes: The actual output voltage root mean square value is compared with the preset reference output voltage root mean square value to obtain the voltage deviation value; The voltage deviation value is input into the proportional-integral controller to generate a control signal, which is then sent to the main circuit to control the main circuit to output a constant voltage.

7. The plasma knife energy control method based on current distortion feedback according to claim 1, characterized in that, The dual closed-loop feedback control strategy based on current distortion in step S4 specifically includes: The calculated actual current distortion index is compared with the preset reference current distortion index to obtain the distortion deviation value; The distortion deviation value is input into the first proportional-integral controller to generate the reference root mean square value of the output voltage. The voltage deviation value is obtained by comparing the reference root mean square value of the output voltage with the actual root mean square value of the actual output voltage. The voltage deviation value is input into the second proportional-integral controller to generate a control signal and send it to the main circuit to adjust the actual output voltage of the main circuit.

8. The plasma knife energy control method based on current distortion feedback according to claim 1, characterized in that, In step S4, during the entire plasma knife operation process, the processor continuously executes steps S1 to S4 in a loop, monitors the load status changes in real time, and dynamically adjusts the output voltage.

9. A plasma knife energy control system based on current distortion feedback, characterized in that, Includes main circuit, sampling circuit and processor; The sampling circuit is connected to the main circuit and the processor respectively, and is used to collect the instantaneous value of the output current, the root mean square value of the output current and the root mean square value of the output voltage of the main circuit, and send the collected signals to the processor. The processor is connected to the main circuit and is used to execute the plasma knife energy control method based on current distortion feedback as described in any one of claims 1 to 8, generate control signals and send them to the main circuit to control the output of the main circuit.

10. The plasma knife energy control system based on current distortion feedback according to claim 9, characterized in that, The sampling circuit includes a current sampling unit and a voltage sampling unit; The current sampling unit includes a current operational amplifier circuit and a current root mean square to DC conversion circuit. The input terminal of the current operational amplifier circuit is connected to the output terminal of the main circuit. The first output terminal of the current operational amplifier circuit is directly connected to the first input terminal of the processor and is used to transmit the instantaneous value of the output current to the processor. The second output terminal of the current operational amplifier circuit is connected to the input terminal of the current root mean square to DC conversion circuit. The output terminal of the current root mean square to DC conversion circuit is connected to the second input terminal of the processor and is used to transmit the root mean square value of the output current to the processor. The voltage sampling unit includes a voltage operational amplifier circuit and a voltage root mean square to DC conversion circuit. The input terminal of the voltage operational amplifier circuit is connected to the output terminal of the main circuit, the output terminal of the voltage operational amplifier circuit is connected to the input terminal of the voltage root mean square to DC conversion circuit, and the output terminal of the voltage root mean square to DC conversion circuit is connected to the third input terminal of the processor, which is used to transmit the root mean square value of the output voltage to the processor. The processor can be any one of a microcontroller, digital signal processor, complex programmable logic device, or field-programmable gate array.

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