Compensation method and system for equivalent reverse flux frequency domain electromagnetic method transmitting system

Abstract

The present invention discloses a compensation method for an equivalent inverse flux frequency domain electromagnetic method transmitting system, comprising connecting a switch capacitor compensation module in series to one end of the input end of a transmitting coil in the equivalent inverse flux frequency domain electromagnetic method transmitting system; obtaining a current signal of a sampling resistor corresponding to the transmitting coil and processing it to obtain a corresponding first square wave signal; obtaining a second square wave signal based on a driving signal of a switching tube and processing the first square wave signal; sampling the second square wave signal and generating a switch control signal for the switch capacitor compensation module based on the sampling signal; and controlling the switch capacitor compensation module using the switch control signal to achieve compensation for the equivalent inverse flux frequency domain electromagnetic method transmitting system. The present invention also discloses a system for achieving the compensation method for the equivalent inverse flux frequency domain electromagnetic method transmitting system. The present invention not only achieves compensation for the equivalent inverse flux frequency domain electromagnetic method transmitting system, but also has high reliability, good accuracy, and a wide range of applications.

Description

Technical Field

[0001] The present invention belongs to the field of geophysical exploration, and in particular relates to a compensation method and system for an equivalent reverse flux frequency domain electromagnetic method transmitting system. Background Art

[0002] Frequency-Domain Electromagnetic Method (FDEM), a geophysical electromagnetic exploration method, has been widely used in fields such as geological hazard prediction, pipeline detection, environmental assessment, and identification of underground unexploded ordnance, achieving excellent results. The equivalent reverse flux FDEM transmission system generally consists of a transmitting coil, a bucking coil, and a receiving coil. By supplying an alternating current to the transmitting coil, a primary electromagnetic field is generated. This primary field propagates underground and induces a secondary field on geological anomalies. The receiving coil receives this secondary field from the underground to obtain subsurface geological information. To ensure received signal strength, the transmitting and receiving coils are often placed in close proximity. The changing primary field generates an induced electromotive force in the coils, affecting the reception of the secondary field signal. Therefore, the bucking coil is used to calculate and offset the induced electromotive force in the receiving coil caused by the primary field changes, thus obtaining pure secondary field information.

[0003] However, in actual implementation, the scheme of using compensation coils for cancellation requires complex calculations and is difficult to avoid errors. The equivalent reverse flux device uses upper and lower parallel coaxial transmitting coils, and passes reverse currents through them respectively, forming a zero flux plane in the center plane of the two transmitting coils. In theory, pure secondary field information can be obtained by receiving on this plane, which is more convenient and efficient. The electromagnetic field will continue to attenuate during the process of underground propagation, and the propagation distance is related to the frequency. FDEM achieves the purpose of depth measurement based on the different skin depths of electromagnetic fields at different frequencies. However, the transmitting coil is inductive and will hinder high-frequency signals, affecting the transmission waveform and transmission power, resulting in a decrease in the signal-to-noise ratio of the received data and a decrease in accuracy, which affects the normal operation of the work.

[0004] To address the issue of the transmitting coil being inductive and blocking high-frequency signals, existing solutions primarily utilize the capacitive reactance of the capacitor to offset the inductive reactance of the coil, making the transmitting circuit purely resistive and resonant, thereby increasing the transmitting current and improving the transmitting power. Depending on whether the frequency of the resonance compensation is adjustable, the various existing compensation methods can be roughly divided into two categories: uncontrollable resonance compensation and controllable resonance compensation.

[0005] The uncontrollable resonance method mainly uses various topologies of capacitors and inductors to compensate for the inductive reactance of the transmitting coil. The characteristic of this type of solution is that once the component parameters are determined, the transmitting frequency that can be compensated is also determined and cannot be changed. To achieve compensation for other frequencies, the only way is to replace the components in the circuit. This type of solution generally includes single capacitor compensation, LC array compensation, and switch-controlled capacitor array compensation solutions. However, the application scenarios of the single capacitor compensation solution are relatively limited, and it is mostly used in situations where only fixed frequencies are of concern. The LC array compensation solution is more difficult to calculate, and its actual application can generally only be targeted at some scenarios that are more concerned about specific frequencies, and the application effect is poor. The switch-controlled capacitor array compensation solution is still limited to the resonant frequencies that can be compensated by the existing capacitors in the array, and its scope of application is relatively small.

[0006] Controllable resonant compensation methods are essentially based on capacitors, but due to improvements in manufacturing processes or the introduction of active devices, the capacitance value can be changed within a certain range, thus achieving controllable resonant compensation. This type of solution mainly includes varactor diode compensation, variable capacitor compensation, active inverter bridge compensation, thyristor series capacitor compensation, and switched capacitor compensation. However, the tunable range of the varactor diode solution is relatively narrow and concentrated in the radio frequency range, and its application is mostly in the radio frequency field; the capacitance of the variable capacitor compensation solution is also mostly concentrated in the pF range, and is mostly used in FM radios; the active inverter bridge compensation solution requires complex control algorithms to control the inverter bridge in actual application and requires real-time calculation of the circuit reactive power, which has certain requirements for the main control circuit's operational performance. In current application cases, the compensation frequency is concentrated in a few hundred hertz; the performance of the thyristor series capacitor compensation solution is affected by the characteristics of the thyristor and is currently mostly used in the low frequency band; the switched capacitor compensation solution is mostly used in the field of magnetically coupled wireless power transmission and usually operates at a fixed frequency. Summary of the Invention

[0007] One of the objectives of the present invention is to provide a compensation method for an equivalent reverse flux frequency domain electromagnetic method transmitting system with high reliability, good accuracy and wide applicability.

[0008] A second object of the present invention is to provide a system for implementing the compensation method of the equivalent reverse flux frequency domain electromagnetic method transmitting system.

[0009] The compensation method of the equivalent reverse flux frequency domain electromagnetic method transmitting system provided by the present invention comprises the following steps:

[0010] S1. A switched capacitor compensation module is connected in series to one end of the input terminal of the transmitting coil in the equivalent reverse flux frequency domain electromagnetic method transmitting system;

[0011] S2. Obtain the current signal of the sampling resistor corresponding to the transmitting coil and process it to obtain the corresponding first square wave signal;

[0012] S3. According to the driving signal of the switch tube and the first square wave signal obtained in step S2, a second square wave signal is obtained by processing;

[0013] S4. Sampling the obtained second square wave signal and generating a switching control signal for the switched capacitor compensation module according to the sampling signal;

[0014] S5. Using the switch control signal obtained in step S4, the switch capacitor compensation module is controlled to achieve compensation of the equivalent reverse flux frequency domain electromagnetic method transmission system.

[0015] The step S1 of connecting a switched capacitor compensation module in series to one end of the input end of the transmitting coil in the equivalent reverse flux frequency domain electromagnetic method transmitting system specifically includes the following steps:

[0016] In the equivalent reverse flux frequency domain electromagnetic method transmitting system, the transmitting coil is connected in series with the sampling resistor and then connected to the output end of the full bridge circuit of the equivalent reverse flux frequency domain electromagnetic method transmitting system;

[0017] One end of the transmitting coil is connected to a sampling resistor; the other end of the transmitting coil is connected in series with a switched capacitor compensation module.

[0018] The switched capacitor compensation module includes a first compensation capacitor, a second compensation capacitor, a first switch, and a second switch; one end of the second compensation capacitor is connected to the transmitting coil, the other end of the second compensation capacitor is connected to the other end of the first compensation capacitor, and one end of the first compensation capacitor is connected to the output end of the full-bridge circuit; the first switch tube and the second switch tube are connected in series and then connected in parallel with the first compensation capacitor;

[0019] The first compensation capacitor is used to realize compensation of the equivalent reverse flux frequency domain electromagnetic method transmitting system; the second compensation capacitor is used to improve the stability of the compensation process; the first switching tube and the second switching tube are used to control the operation of the switching capacitor compensation module.

[0020] The equivalent capacitance of the switched capacitor compensation module specifically includes the following steps:

[0021] The equivalent capacitance C of the switched capacitor compensation module is calculated using the following formula: eq :

[0022]

[0023] Wherein, C1 is the capacitance value of the first compensation capacitor; C2 is the capacitance value of the second compensation capacitor; and α is the conduction angle of the first switching tube or the second switching tube.

[0024] The capacitance value of the first compensation capacitor and the capacitance value of the second compensation capacitor are specifically determined by the following steps:

[0025] The capacitance value of the first compensation capacitor and the capacitance value of the second compensation capacitor are calculated using the following steps:

[0026] According to the target transmission frequency and the inductance of the transmitting coil, the equivalent capacitance value C required to complete the compensation is calculated using the following formula eq1 :

[0027]

[0028] Where f is the transmitting frequency, L is the transmitting coil inductance; since C1<C eq1 <C2, so after leaving a set margin, the capacitance value of the first compensation capacitor and the capacitance value of the second compensation capacitor are calculated according to the upper limit and lower limit of the target transmission frequency band.

[0029] The step S2 of obtaining the current signal of the sampling resistor corresponding to the transmitting coil and processing it to obtain the corresponding first square wave signal specifically includes the following steps:

[0030] Obtaining the current signal of the sampling resistor connected to the transmitting coil;

[0031] The obtained current signal is subjected to zero-crossing comparison to obtain a first square wave signal.

[0032] The step S3 of processing the driving signal of the switch tube and the first square wave signal obtained in step S2 to obtain the second square wave signal specifically includes the following steps:

[0033] An XOR operation is performed on the driving signal of the switch tube that is in phase with the output voltage of the full-bridge circuit and the first square wave signal obtained in step S2 to obtain a second square wave signal.

[0034] The step S4 of sampling the obtained second square wave signal and generating a switch control signal of the switched capacitor compensation module according to the sampled signal specifically includes the following steps:

[0035] Low-pass filtering is performed on the obtained second square wave signal to obtain a DC signal representing the phase difference between the voltage and current of the transmitting coil, and then the DC signal is sampled and the sampled signal is calculated using a PID control algorithm to obtain a first control signal;

[0036] Comparing the obtained first control signal with the set sawtooth wave signal to obtain a first PWM control signal;

[0037] The first PWM control signal is used as the control signal of the first switch tube in the switched capacitor compensation module, and the first PWM control signal is delayed by 180° and used as the control signal of the second switch tube in the switched capacitor compensation module.

[0038] The PID control algorithm specifically includes the following steps:

[0039] During initialization, ensure that the full-bridge circuit of the equivalent reverse flux frequency domain electromagnetic method transmitting system is an inductive circuit;

[0040] The DC signal representing the phase difference between the voltage and current of the transmitting coil obtained after the second square wave signal is low-pass filtered is set as the error value;

[0041] In the PID control process, if the error value of the control period T is less than the average value of the period error, the error signal is directly used as the input of the PID control algorithm; if the error value of the control period T is greater than the average value of the period error, the error signal is inverted and used as the input of the PID control algorithm;

[0042] The average value of the period error is the average value of the error values ​​during the control period T-1 to the control period Tn, where n is the set average period value.

[0043] The present invention also provides a system for implementing the compensation method of the equivalent inverse flux frequency domain electromagnetic method transmitting system, comprising a circuit connection module, a first square wave module, a second square wave module, a control module and a compensation module; the circuit connection module, the first square wave module, the second square wave module, the control module and the compensation module are connected in series in sequence; the circuit connection module is used to connect the switching capacitor compensation module in series at one end of the input end of the transmitting coil in the equivalent inverse flux frequency domain electromagnetic method transmitting system, and upload the data information to the first square wave module; the first square wave module is used to obtain the current signal of the sampling resistor corresponding to the transmitting coil according to the received data information, and process it to obtain the corresponding first square wave signal, and The data information is uploaded to the second square wave module; the second square wave module is used to process the received data information, the driving signal of the switch tube corresponding to the transmitting coil and the obtained first square wave signal to obtain a second square wave signal, and upload the data information to the control module; the control module is used to sample the obtained second square wave signal according to the received data information, and generate a switch control signal of the switch capacitor compensation module according to the sampled signal, and upload the data information to the compensation module; the compensation module is used to control the switch capacitor compensation module according to the received data information and the obtained switch control signal to realize compensation of the equivalent reverse flux frequency domain electromagnetic method transmitting system.

[0044] The compensation method and system for the equivalent inverse flux frequency domain electromagnetic method transmitting system provided by the present invention, by connecting a switching capacitor compensation module in series to the output end of the equivalent inverse flux frequency domain electromagnetic method transmitting system and controlling the switching capacitor compensation module according to the output of the equivalent inverse flux frequency domain electromagnetic method transmitting system, not only realizes the compensation of the equivalent inverse flux frequency domain electromagnetic method transmitting system, but also has higher reliability, better accuracy and wider scope of application. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Schematic diagram of the process of the present invention.

[0046] Figure 2 The figure is a schematic diagram showing the connection between the switched capacitor compensation module in the method of the present invention and the full-bridge circuit of the equivalent reverse flux frequency domain electromagnetic method transmitting system.

[0047] Figure 3 Schematic diagram of the functional modules of the system of the present invention. DETAILED DESCRIPTION

[0048] like Figure 1 The figure shows a schematic flow chart of the method of the present invention: the compensation method of the equivalent reverse flux frequency domain electromagnetic method transmitting system provided by the present invention comprises the following steps:

[0049] S1. Connecting a switched capacitor compensation module in series to one end of the input terminal of the transmitting coil in the equivalent reverse flux frequency domain electromagnetic method transmitting system; specifically comprising the following steps:

[0050] In the equivalent reverse flux frequency domain electromagnetic method transmitting system, the transmitting coil is connected in series with the sampling resistor and then connected to the output end of the full bridge circuit of the equivalent reverse flux frequency domain electromagnetic method transmitting system;

[0051] One end of the transmitting coil is connected to a sampling resistor; the other end of the transmitting coil is connected in series with a switched capacitor compensation module;

[0052] In specific implementation, the switch capacitor compensation module is as follows: Figure 2 As shown, it includes a first compensation capacitor C1, a second compensation capacitor C2, a first switch Q1 and a second switch Q2; one end of the second compensation capacitor is connected to the transmitting coil (the transmitting coil equivalent model is marked in the figure), the other end of the second compensation capacitor is connected to the other end of the first compensation capacitor, and one end of the first compensation capacitor is connected to the output terminal B of the full-bridge circuit; the first switch tube and the second switch tube are connected in series and then connected in parallel with the first compensation capacitor;

[0053] The first compensation capacitor is used to achieve compensation of the equivalent reverse flux frequency domain electromagnetic method transmission system; the second compensation capacitor is used to improve the stability of the compensation process; the first switching tube and the second switching tube are used to control the operation of the switch capacitor compensation module;

[0054] At the same time, the equivalent capacitance C of the switch capacitor compensation module is calculated using the following formula: eq :

[0055]

[0056] Where C1 is the capacitance value of the first compensation capacitor; C2 is the capacitance value of the second compensation capacitor; α is the conduction angle of the first switch tube or the second switch tube;

[0057] In addition, the capacitance value of the first compensation capacitor and the capacitance value of the second compensation capacitor are calculated using the following steps:

[0058] According to the target transmission frequency and the inductance of the transmitting coil, the equivalent capacitance value C required to complete the compensation is calculated using the following formula eq1 :

[0059]

[0060] Where f is the transmitting frequency, L is the transmitting coil inductance; since C1<C eq1 <C2, so after leaving a set margin, the capacitance value of the first compensation capacitor and the capacitance value of the second compensation capacitor are calculated according to the upper and lower limits of the target transmission frequency band;

[0061] S2. Obtain the current signal of the sampling resistor corresponding to the transmitting coil and process it to obtain the corresponding first square wave signal; specifically comprising the following steps:

[0062] Get the sampling resistance connected to the transmitting coil ( Figure 2 R in the middle T ) of the current signal ( Figure 2 i in the middle T );

[0063] Perform zero-crossing comparison on the obtained current signal to obtain a first square wave signal;

[0064] S3. According to the driving signal of the switch tube and the first square wave signal obtained in step S2, a second square wave signal is obtained by processing; specifically comprising the following steps:

[0065] Performing an XOR operation on the driving signal having the same phase as the output voltage of the full-bridge circuit and the first square wave signal obtained in step S2 to obtain a second square wave signal;

[0066] S4. Sampling the obtained second square wave signal and generating a switch control signal for the switched capacitor compensation module according to the sampled signal; specifically comprising the following steps:

[0067] Low-pass filtering is performed on the obtained second square wave signal to obtain a DC signal representing the phase difference between the voltage and current of the transmitting coil, and then the DC signal is sampled and the sampled signal is calculated using a PID control algorithm to obtain a first control signal;

[0068] Comparing the obtained first control signal with the set sawtooth wave signal to obtain a first PWM control signal;

[0069] The first PWM control signal is used as the control signal of the first switch tube in the switched capacitor compensation module, and the first PWM control signal is delayed by 180 degrees and used as the control signal of the second switch tube in the switched capacitor compensation module;

[0070] When implemented, the PID control algorithm includes the following steps:

[0071] During initialization, ensure that the full-bridge circuit of the equivalent reverse flux frequency domain electromagnetic method transmitting system is an inductive circuit;

[0072] The DC signal representing the phase difference between the voltage and current of the transmitting coil obtained after the second square wave signal is low-pass filtered is set as the error value;

[0073] When the output voltage and current of the full-bridge circuit are in phase, it indicates that the load is resistive as a whole, which is also the target of resonant compensation. At this time, the duty cycle of the square wave after XOR is zero, and the output is zero after low-pass filtering. When the circuit is inductive / capacitive, the current lags / leads the voltage; however, regardless of whether the circuit is inductive or capacitive, the voltage value after low-pass filtering is positive, so it is necessary to actively determine the direction of error deviation, that is, to determine the sign of the error. Therefore, the following scheme is adopted: During the PID control process, if the error value of the control period T is less than the average value of the period error, the error signal is directly used as the input of the PID control algorithm; if the error value of the control period T is greater than the average value of the period error, the error increases instead of decreases, indicating that the circuit is over-regulated. Therefore, the error signal is inverted and used as the input of the PID control algorithm to continue regulating the circuit in the resistive direction; this cycle continues until the regulation is stable and the error value of the control period T is equal to the average value of the period error;

[0074] The average value of the period error is the average value of the error values ​​during the control period T-1 to the control period Tn, where n is the set average period value;

[0075] S5. Using the switch control signal obtained in step S4, the switch capacitor compensation module is controlled to achieve compensation of the equivalent reverse flux frequency domain electromagnetic method transmission system.

[0076] like Figure 3The figure shows a schematic diagram of the functional modules of the system of the present invention: the system disclosed in the present invention for realizing the compensation method of the equivalent inverse flux frequency domain electromagnetic method transmitting system comprises a circuit connection module, a first square wave module, a second square wave module, a control module and a compensation module; the circuit connection module, the first square wave module, the second square wave module, the control module and the compensation module are connected in series in sequence; the circuit connection module is used to connect the switching capacitor compensation module in series at one end of the input end of the transmitting coil in the equivalent inverse flux frequency domain electromagnetic method transmitting system, and upload the data information to the first square wave module; the first square wave module is used to obtain the current signal of the sampling resistor corresponding to the transmitting coil according to the received data information, and process it to obtain the corresponding The first square wave signal is transmitted and the data information is uploaded to the second square wave module; the second square wave module is used to process the received data information, the driving signal of the switching tube corresponding to the transmitting coil and the obtained first square wave signal to obtain a second square wave signal, and upload the data information to the control module; the control module is used to sample the obtained second square wave signal according to the received data information, and generate a switching control signal of the switching capacitor compensation module according to the sampling signal, and upload the data information to the compensation module; the compensation module is used to control the switching capacitor compensation module according to the received data information and the obtained switching control signal to realize compensation of the equivalent inverse flux frequency domain electromagnetic method transmitting system.

Claims

1. A compensation method for an equivalent reverse flux frequency domain electromagnetic method transmitting system, comprising the following steps: S1. A switched capacitor compensation module is connected in series to one end of the input terminal of the transmitting coil in the equivalent reverse flux frequency domain electromagnetic method transmitting system; S2. Obtain the current signal of the sampling resistor corresponding to the transmitting coil and process it to obtain the corresponding first square wave signal; S3. According to the driving signal and the first square wave signal obtained in step S2, a second square wave signal is obtained by processing; S4. Sampling the obtained second square wave signal and generating a switching control signal for the switched capacitor compensation module according to the sampling signal; S5. Using the switch control signal obtained in step S4, the switch capacitor compensation module is controlled to achieve compensation of the equivalent reverse flux frequency domain electromagnetic method transmission system.

2. The compensation method for the equivalent reverse flux frequency domain electromagnetic method transmitting system according to claim 1 is characterized in that The step S1 of connecting a switched capacitor compensation module in series to one end of the input end of the transmitting coil in the equivalent reverse flux frequency domain electromagnetic method transmitting system specifically includes the following steps: In the equivalent reverse flux frequency domain electromagnetic method transmitting system, the transmitting coil is connected in series with the sampling resistor and then connected to the output end of the full bridge circuit of the equivalent reverse flux frequency domain electromagnetic method transmitting system; One end of the transmitting coil is connected to a sampling resistor; the other end of the transmitting coil is connected in series with a switched capacitor compensation module.

3. The compensation method for the equivalent reverse flux frequency domain electromagnetic method transmitting system according to claim 2 is characterized in that The switched capacitor compensation module includes a first compensation capacitor, a second compensation capacitor, a first switch, and a second switch; one end of the second compensation capacitor is connected to the transmitting coil, the other end of the second compensation capacitor is connected to the other end of the first compensation capacitor, and one end of the first compensation capacitor is connected to the output end of the full-bridge circuit; The first switch tube and the second switch tube are connected in series, and then connected in parallel with the first compensation capacitor; The first compensation capacitor is used to realize compensation of the equivalent reverse flux frequency domain electromagnetic method transmitting system; the second compensation capacitor is used to improve the stability of the compensation process; The first switch tube and the second switch tube are used to control the operation of the switched capacitor compensation module.

4. The compensation method for the equivalent reverse flux frequency domain electromagnetic method transmitting system according to claim 3 is characterized in that The equivalent capacitance of the switched capacitor compensation module specifically includes the following steps: The equivalent capacitance C of the switched capacitor compensation module is calculated using the following formula: eq : Wherein, C1 is the capacitance value of the first compensation capacitor; C2 is the capacitance value of the second compensation capacitor; and α is the conduction angle of the first switching tube or the second switching tube.

5. The compensation method for the equivalent reverse flux frequency domain electromagnetic method transmitting system according to claim 4 is characterized in that The capacitance value of the first compensation capacitor and the capacitance value of the second compensation capacitor are specifically determined by the following steps: The capacitance value of the first compensation capacitor and the capacitance value of the second compensation capacitor are calculated using the following steps: According to the target transmission frequency and the inductance of the transmitting coil, the equivalent capacitance value C required to complete the compensation is calculated using the following formula eq1 : Where f is the transmitting frequency, L is the transmitting coil inductance; since C1<C eq1 <C2, so after leaving a set margin, the capacitance value of the first compensation capacitor and the capacitance value of the second compensation capacitor are calculated according to the upper limit and lower limit of the target transmission frequency band.

6. The compensation method for the equivalent reverse flux frequency domain electromagnetic method transmitting system according to claim 5 is characterized in that The step S2 of obtaining the current signal of the sampling resistor corresponding to the transmitting coil and processing it to obtain the corresponding first square wave signal specifically includes the following steps: Obtaining the current signal of the sampling resistor connected to the transmitting coil; The obtained current signal is subjected to zero-crossing comparison to obtain a first square wave signal.

7. The compensation method for the equivalent reverse flux frequency domain electromagnetic method transmitting system according to claim 6 is characterized in that The step S3 of processing the driving signal of the switch tube and the first square wave signal obtained in step S2 to obtain the second square wave signal specifically includes the following steps: An XOR operation is performed on the driving signal of the switch tube that is in phase with the output voltage of the full-bridge circuit and the first square wave signal obtained in step S2 to obtain a second square wave signal.

8. The compensation method for the equivalent reverse flux frequency domain electromagnetic method transmitting system according to claim 7 is characterized in that The step S4 of sampling the obtained second square wave signal and generating a switch control signal of the switched capacitor compensation module according to the sampled signal specifically includes the following steps: Low-pass filtering is performed on the obtained second square wave signal to obtain a DC signal representing the phase difference between the voltage and current of the transmitting coil, and then the DC signal is sampled and the sampled signal is calculated using a PID control algorithm to obtain a first control signal; Comparing the obtained first control signal with the set sawtooth wave signal to obtain a first PWM control signal; The first PWM control signal is used as the control signal of the first switch tube in the switched capacitor compensation module, and the first PWM control signal is delayed by 180° and used as the control signal of the second switch tube in the switched capacitor compensation module.

9. The compensation method for the equivalent reverse flux frequency domain electromagnetic method transmitting system according to claim 8, characterized in that The PID control algorithm specifically includes the following steps: During initialization, ensure that the full-bridge circuit of the equivalent reverse flux frequency domain electromagnetic method transmitting system is an inductive circuit; The DC signal representing the phase difference between the voltage and current of the transmitting coil obtained after the second square wave signal is low-pass filtered is set as the error value; In the PID control process, if the error value of the control period T is less than the average value of the period error, the error signal is directly used as the input of the PID control algorithm; if the error value of the control period T is greater than the average value of the period error, the error signal is inverted and used as the input of the PID control algorithm; The average value of the period error is the average value of the error values ​​during the control period T-1 to the control period Tn, where n is the set average period value.

10. A system for implementing the compensation method of the equivalent reverse flux frequency domain electromagnetic transmission system according to any one of claims 1 to 9, characterized in that It includes a circuit connection module, a first square wave module, a second square wave module, a control module and a compensation module; the circuit connection module, the first square wave module, the second square wave module, the control module and the compensation module are connected in series in sequence; the circuit connection module is used to connect the switch capacitor compensation module in series at one end of the input end of the transmitting coil in the equivalent reverse flux frequency domain electromagnetic method transmitting system, and upload the data information to the first square wave module; the first square wave module is used to obtain the current signal of the sampling resistor corresponding to the transmitting coil according to the received data information, and process it to obtain the corresponding first square wave signal, and upload the data information to the second square wave module; the second square wave module is used to process the second square wave signal according to the received data information, the driving signal of the switch tube corresponding to the transmitting coil and the obtained first square wave signal, and upload the data information to the control module; The control module is used to sample the second square wave signal obtained according to the received data information, generate a switch control signal of the switch capacitor compensation module according to the sampled signal, and upload the data information to the compensation module; The compensation module is used to control the switch capacitor compensation module according to the received data information and the obtained switch control signal to achieve compensation of the equivalent reverse flux frequency domain electromagnetic method transmission system.

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