Intermittent synchronous dual-stage high-voltage source system for airborne electromagnetic prospecting

Abstract

The application belongs to the field of airborne electromagnetic detection and relates to an intermittent synchronous double-stage high-voltage source system for airborne electromagnetic detection, which comprises: a first power supply, which converts input low-voltage direct current into first high-voltage direct current to supply power to a second power supply; the second power supply, which raises the first high-voltage direct current to second high-voltage direct current of a required level; a PID negative feedback control circuit, which measures and detects the output voltage of the second power supply and adjusts the output voltage of the second power supply through the relationship between the output voltage and the input voltage of the first power supply; a synchronous signal receiving circuit, which controls the output of the second power supply to be synchronized with the transmitter by receiving the synchronous signal of the transmitter; and a CAN control module, which adjusts the level of the output voltage of the second power supply by receiving the instruction of an upper computer. The application adopts a two-stage power supply mode to raise the voltage to a maximum of 750 V. Compared with a traditional voltage source, the voltage level is higher, the stability is higher, and the noise is smaller.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of airborne electromagnetic detection, and particularly relates to an intermittent synchronous double-stage high-voltage source system for airborne electromagnetic detection. BACKGROUND

[0002] Compared with methods commonly used in resource detection such as seismic method, magnetic method and ground penetrating radar, electromagnetic prospecting has the characteristics of large detection area and high detection efficiency, and is widely applied in the field of underground mineral resource exploration.

[0003] Among many electromagnetic prospecting methods, the helicopter transient electromagnetic method is a method for finding ore bodies or solving some geological problems by using an airplane to carry observation instruments, inducing a secondary field in the underground geological body by the excited electromagnetic field, and researching the spatial and temporal characteristics of the secondary field on the basis of electromagnetic induction principle. The fundamental purpose is to explore the electrical property distribution of the underground target body through analysis of the measured data.

[0004] The high-voltage power supply is mainly related to the transmitter part of the airborne electromagnetic detection, and is used for converting the 28V electricity provided by the helicopter platform into high-voltage of 700V or above, providing high-voltage for the transmitting part. In the case of high voltage and large current, the magnetic moment of the transmitter can be increased. The airborne electromagnetic detection system is commonly used for geological exploration and underground resource exploration. Since the present stage of ore prospecting has entered the stage of deep exploration, the secondary field signal returned by the ground after the magnetic field excited by the transmitting coil is weak, the sensor sensitivity of the receiving coil is very high, the traditional power supply also works when the receiver works, which will interfere with the receiving coil and cause interference. While increasing the transmitting magnetic moment, the interference to the receiver is reduced.

[0005] For the transmitter power supply of the airborne electromagnetic detection, the main transmitter power supply voltage level is mainly 400-500V, and there is no relative special design for the electromagnetic transmission system. For deep exploration, the voltage level is low, it is difficult to excite ideal secondary field signals, and there is no power supply system that stops working when the receiver works. Moreover, one of the reasons for the limited magnetic moment at the present stage is that the voltage level of the power supply is low, and the interference to the receiver is large, which affects the receiver. At the same time, the interference generated by the power supply cannot be ignored. SUMMARY

[0006] The embodiment of the application provides an intermittent synchronous double-stage high-voltage source system for airborne electromagnetic detection, which solves the problems of low power supply voltage level in the transmitting device and the influence of power supply noise on the receiver.

[0007] The embodiment of the application provides an intermittent synchronous double-stage high-voltage source system for airborne electromagnetic detection, which solves the problems of low power supply voltage level in the transmitting device and the influence of power supply noise on the receiver.

[0008] The first power supply converts the input low-voltage direct current into first high-voltage direct current to supply power for the second power supply;

[0009] The second power supply raises the first high-voltage direct current to second high-voltage direct current of a required level;

[0010] The PID negative feedback control circuit detects the output voltage of the second power supply by measurement, and adjusts the output voltage of the second power supply through the relationship between the output voltage and the input voltage of the first power supply;

[0011] The synchronous signal receiving circuit controls the output of the second power supply to be synchronized with the transmitter by receiving the synchronous signal of the transmitter;

[0012] The CAN control module adjusts the level of the output voltage of the second power supply by receiving the instruction of the upper computer.

[0013] Further, the first power supply comprises:

[0014] The boost circuit comprises a first transformer and a first switching device in a push-pull structure, the first switching device comprising a switching tube Q1, a switching tube Q2, a switching tube Q3 and a switching tube Q4, the drain electrode of the switching tube Q1 being connected with the drain electrode of the switching tube Q3 and connected to one end of the primary side of the first transformer, the source electrode of the switching tube Q1 being connected with the drain electrode of the switching tube Q2, the source electrode of the switching tube Q3 being connected with the drain electrode of the switching tube Q4, the source electrode of the switching tube Q4 being connected with the source electrode of the switching tube Q2 and connected to the other end of the primary side of the first transformer, and the source electrode of the switching tube Q1 and the source electrode of the switching tube Q3 being connected to the negative electrode of the helicopter power supply;

[0015] The first protection circuit is connected to the positive electrode of the power supply at one end and connected to the intermediate tap of the first transformer at the other end;

[0016] The first rectifier circuit adopts a bridge rectifier circuit and is connected to the secondary side of the first transformer through two input ends, one positive electrode end and one negative electrode end serving as the output end of the first power supply.

[0017] Further, the second power supply comprises:

[0018] The LLC resonant boost circuit comprises four groups of parallel switching tubes and a second transformer, wherein the intermediate tap of the first group of switching tubes is connected to the first end of a resonant inductor Lr, the second end of the resonant inductor Lr is connected to the first end of the primary side of the second transformer, the intermediate tap of the third group of switching tubes is connected to the first end of a resonant capacitor Cr, the second end of the resonant capacitor Cr is connected to the second end of the primary side of the second transformer; and the primary side of the second transformer is connected in parallel with a transformer leakage inductor Lm;

[0019] The second rectifier circuit adopts a bridge rectifier circuit, and is connected with the secondary side of the second transformer through two input ends, and has one positive terminal and one negative terminal as output terminals of the second-level power supply; the positive terminal and the negative terminal are connected in parallel with a capacitor C1 and a resistor R.

[0020] Further, the first rectifier circuit includes four diodes connected in a head-to-tail manner, wherein a first diode D1 and a second diode D2 form a second connection end, the first diode D1 and a fourth diode D4 form a first connection end, the second diode D2 and a third diode D3 form a third connection end, and the third diode D3 and the fourth diode D4 form a fourth connection end; the first connection end is connected to one end of the secondary side of the first transformer, the third connection end is connected to the other end of the secondary side of the first transformer, and the second connection end and the fourth connection end are output terminals of the first-level power supply.

[0021] Further, the second rectifier circuit includes four diodes connected in a head-to-tail manner, wherein a first diode D5 and a second diode D6 form a second connection end, the first diode D5 and a fourth diode D8 form a first connection end, the second diode D6 and a third diode D7 form a third connection end, and the third diode D7 and the fourth diode D8 form a fourth connection end; the first connection end is connected to one end of the secondary side of the second transformer, the third connection end is connected to the other end of the secondary side of the second transformer, and the second connection end and the fourth connection end are output terminals of the second-level power supply.

[0022] Further, the PID negative feedback control circuit includes a first single-chip microcomputer, which collects an output voltage signal of the second-level power supply through a circuit R, converts the voltage signal into an analog voltage signal in a voltage range suitable for processing by the first single-chip microcomputer through a signal conditioning circuit, inputs the conditioned analog voltage signal into an on-chip ADC module of the first single-chip microcomputer to complete digital-to-analog conversion, and outputs a control quantity based on a deviation between a current sampling value and a set target value through a PID control program stored in the first single-chip microcomputer, converts the control quantity into a pulse width modulation signal through an EPWM module of the first single-chip microcomputer, and applies the pulse width modulation signal to a switching tube of the second-level power supply to dynamically adjust on / off time of the switching tube.

[0023] Further, the synchronous signal receiving circuit includes a second single-chip microcomputer and a power switch, the power switch is connected between an output end of the second-level power supply and the transmitter, a control end of the power switch is connected to the second single-chip microcomputer, and the second single-chip microcomputer outputs a control signal to control the power switch to turn on and turn off according to the synchronous signal received by the transmitter.

[0024] Further, the CAN control module includes a third single-chip microcomputer and a CAN bus, the third single-chip microcomputer communicates with an upper computer, the upper computer obtains transmission current data from the transmitter, and the third single-chip microcomputer controls the switching tube of the second-level power supply to turn on and turn off according to the transmission current data through the CAN bus.

[0025] Further, the working method of the intermittent synchronous two-stage high-voltage source system for airborne electromagnetic exploration comprises:

[0026] The 28V power output from the helicopter flows into the first-stage power supply, enters the boost circuit after passing through the first protection circuit of the first-stage power supply, is converted into alternating current after passing through the parallel shunt of the first switching device and then turns on, is output after being boosted by the first transformer, and then passes through the first rectifier circuit to output 310-320V first high-voltage direct current.

[0027] The first high-voltage direct current is boosted by the LLC resonant boost circuit of the second-stage power supply and is converted into second high-voltage direct current of a required level.

[0028] According to the output voltage level requirement set by the upper computer, the switching tube of the second-stage power supply is adjusted to realize adjustment of the level of the second high-voltage direct current.

[0029] The second high-voltage direct current is collected, and a control amount is output by the PID negative feedback control circuit based on the deviation of the current sampling value from the set target value, and is applied to the switching tube of the second-stage power supply to control the duty cycle of the drive waveform.

[0030] Further, the method further comprises receiving a synchronization signal of a transmitter, and a synchronization signal receiving circuit outputs a control signal based on the synchronization signal and applies the control signal to a power supply switch to control the turn-on and turn-off of the power supply switch.

[0031] Compared with the prior art, the application has the beneficial effects that: the application adopts a two-stage power supply mode, utilizes push-pull resonant boost and LLC resonant boost respectively, and the two-stage power supply can boost the voltage to a maximum of 750V, which is higher in voltage level, higher in stability, and smaller in noise compared with a traditional voltage source.

[0032] The application can use the upper computer to send instructions to realize communication through the CAN bus, can change the voltage level in real time, has faster response speed, higher efficiency, and higher accuracy. Moreover, the application can use PID to realize voltage negative feedback adjustment to ensure the stability of the output voltage. Compared with the previous manual voltage level adjustment mode, the application is more concise, more convenient, and more accurate.

[0033] The application can receive a synchronization signal of a transmitter, the transmitter sends the synchronization signal to a synchronization signal receiving circuit, signal reception is realized by using the synchronization signal receiving circuit in the second-stage power supply, and whether the power supply system works is determined according to the content of the synchronization signal. Thus, interference caused by the receiver working when the power supply works is avoided, and the influence on the later data processing is avoided. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1A module block diagram of an intermittent synchronous two-stage high-voltage source system for airborne electromagnetic detection is provided for the embodiments of the present application.

[0035] Figure 2 A two-stage power supply boosting topological graph of the intermittent synchronous two-stage high-voltage source system for airborne electromagnetic detection is provided for the embodiments of the present application. DETAILED DESCRIPTION

[0036] In order to make the purposes, technical solutions and advantages of the present application clearer and more apparent, the present application is further described in detail below in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0037] At the present stage, in the airborne exploration system of the helicopter airborne transient electromagnetic system, the part of the transmitter power supply is generally used with the highest level of power supply voltage of 500V up and down due to the particularity of the power supply on the helicopter. It is sufficient for the geological exploration work of the conventional terrain, but the current resource exploration target has turned to the high-altitude and complex terrain area. The requirement for the magnetic moment of the transmitter is getting higher and higher, which means that the voltage level of the power supply is getting higher and higher. Therefore, it is imperative to improve the voltage of the power supply. Moreover, the required voltage level is different for different regions. The power supply at the present stage is difficult to realize real-time adjustment. In general, the adjustment is relatively complex. The noise interference generated by the power supply system in the working process is a key problem. The commonly used general power supply needs to continuously supply power to the transmitting subsystem during the execution of the transmitter and in the standby state. In particular, the above power supply noise significantly interferes with the performance of the receiving subsystem during the key stage of the suspension of the transmission operation and the start of the receiver.

[0038] The present application is based on the need of the airborne electromagnetic detection device to solve the problems of low power supply voltage level and noise interference in the transmitting device.

[0039] Referring to Figure 1 the module block diagram of the intermittent synchronous two-stage high-voltage source system for airborne electromagnetic detection and the two-stage power supply boosting topological graph of the intermittent synchronous two-stage high-voltage source system for airborne electromagnetic detection shown in Figure 2 the present application provides an intermittent synchronous two-stage high-voltage source system for airborne electromagnetic detection, which comprises:

[0040] The first-stage power supply converts the input low-voltage direct current into first high-voltage direct current to supply power to the second-stage power supply.

[0041] The second-stage power supply raises the first high-voltage direct current to second high-voltage direct current of the required level.

[0042] PID negative feedback control circuit, using the output voltage of the second power supply measurement detection, through the output voltage and the input voltage of the first power supply relationship adjustment of the output voltage of the second power supply;

[0043] Synchronization signal receiving circuit, by receiving the synchronization signal of the transmitter, control the second power supply output and the transmitter synchronization;

[0044] CAN control module, by receiving the instruction of the host computer, adjust the level of the output voltage of the second power supply.

[0045] Wherein, the first power supply includes: boost circuit, including the first transformer and the first switching device of push-pull structure, the first switching device includes switch tube Q1, switch tube Q2, switch tube Q3 and switch tube Q4, the drain of switch tube Q1 is connected with the drain of switch tube Q3, and is connected to one end of the primary side of the first transformer, the source of switch tube Q1 is connected with the drain of switch tube Q2, the source of switch tube Q3 is connected with the drain of switch tube Q4, the source of switch tube Q4 is connected with the source of switch tube Q2, and is connected to the other end of the primary side of the first transformer, the source of switch tube Q1 and the source of switch tube Q3 are connected to the negative electrode of the helicopter power supply; by connecting the switch tube in parallel, current shunting is carried out, which prevents the switch tube from burning out due to high current.

[0046] The first protection circuit is connected to the positive electrode of the power supply at one end and to the intermediate tap of the first transformer at the other end. The first protection circuit includes a voltage protection circuit and an anti-reverse connection circuit to prevent the helicopter input voltage from being too high or the positive and negative electrodes of the power supply from being connected in reverse, which can damage the power supply and affect the normal operation of the transmitter and subsequent systems. It is realized by using a conventional circuit structure.

[0047] The first rectifier circuit uses a bridge rectifier circuit, which is connected to the secondary side of the first transformer through two input ends, and a positive electrode end and a negative electrode end as the output end of the first power supply.

[0048] The first switching device is driven by a driving circuit, which provides a driving signal for the MOSFET of the first power supply. The output waveform is a square wave with a maximum value of 10V. It can stably provide a driving signal to control the turn-off and turn-on of the first switching device. The driving circuit can be integrated on the first power supply.

[0049] When selecting the first switching device of the first power supply, a small voltage and a large current should be selected. Small MOSFET tubes should be selected and connected in parallel. The maximum withstand voltage of the small MOSFET tube should be greater than 50V. Due to the heat effect, heat sinks and cooling fans are added. The reverse withstand voltage of the diode selected for the first rectifier circuit should be at least twice the output voltage. The first switching device uses a driving circuit to drive the conduction and shutdown of the switch tube.

[0050] The specific working process of the voltage boosting circuit is as follows: after the direct current voltage input is driven by the voltage boosting circuit, the input direct current is converted into high-frequency alternating square wave electricity through the alternate conduction and shutdown of the first switching device; the alternating square wave electricity realizes electrical isolation and voltage boosting through the first transformer, and outputs the first high-voltage alternating current; then, the first high-voltage alternating current is rectified and filtered through the first rectifier circuit, and finally outputs the first high-voltage direct current that can be used by the subsequent circuit, thereby providing a stable input voltage for the second-stage power supply.

[0051] In an embodiment, the second-stage power supply comprises:

[0052] The LLC resonant voltage boosting circuit comprises four groups of parallel switching tubes and a second transformer, each group of switching tubes comprising two switching tubes, wherein the middle tap of the first group of switching tubes is connected to the first end of the resonant inductor Lr, the second end of the resonant inductor Lr is connected to the first end of the primary side of the second transformer, the middle tap of the third group of switching tubes is connected to the first end of the resonant capacitor Cr, and the second end of the resonant capacitor Cr is connected to the second end of the primary side of the second transformer; the primary side of the second transformer is connected in parallel with the transformer leakage inductor Lm.

[0053] The four groups of parallel switching tubes comprise switching tube Q5, switching tube Q6, switching tube Q7, switching tube Q8, switching tube Q9, switching tube Q10, switching tube Q11 and switching tube Q12, switching tube Q5 and switching tube Q9 constitute the first group of switching tubes, switching tube Q6 and switching tube Q10 constitute the second group of switching tubes, switching tube Q7 and switching tube Q11 constitute the third group of switching tubes, and switching tube Q8 and switching tube Q12 constitute the fourth group of switching tubes.

[0054] The drain of switching tube Q5 is connected to the drains of switching tube Q6, switching tube Q7 and switching tube Q8, the source of switching tube Q5 is connected to the drain of switching tube Q9, the source of switching tube Q6 is connected to the drain of switching tube Q10, the source of switching tube Q7 is connected to the drain of switching tube Q11, the source of switching tube Q8 is connected to the drain of switching tube Q12, the sources of switching tube Q9, switching tube Q10, switching tube Q11 and switching tube Q12 are connected, the source of switching tube Q5 is connected to the first end of the resonant inductor Lr, and the source of switching tube Q7 is connected to the first end of the resonant capacitor Cr.

[0055] The second rectifier circuit adopts a bridge rectifier circuit, is connected to the secondary side of the second transformer through two input ends, has one positive terminal and one negative terminal as the output terminals of the second-stage power supply, and has the capacitor C1 and the resistor R connected in parallel between the positive terminal and the negative terminal.

[0056] The LLC resonant boost circuit is used in the second power supply, which can realize soft switching and reduce switching loss. The CAN control module is adopted to realize adjustable output voltage value, and the output voltage is changed through the control of the upper computer. The LLC resonant boost circuit of the second power supply converts the input DC voltage into AC square wave voltage through four groups of parallel connected switch tubes under the action of the resonant circuit composed of resonant inductor Lr and resonant capacitor Cr, realizes soft switching, and converts the input voltage into higher voltage through the second transformer. After rectification by the second rectifier circuit, the DC voltage is output. The output voltage is provided from 50V to 750V to the transmitter to supply power. The resonant circuit realizes zero voltage switching of the second power supply. Before the switch tube is turned on, the resonant circuit can make the voltage across the switch tube drop to zero, realizing zero voltage switching. This means that the switch tube is turned on when the voltage is zero, thereby avoiding voltage spikes and related losses when turned on. Before the switch device is turned off, the resonant circuit can make the current flowing through the switch tube drop to zero, realizing zero current switching.

[0057] In an embodiment, the rectifier circuit structures in the first power supply and the second power supply are the same, specifically:

[0058] The first rectifier circuit includes four diodes connected in a loop, wherein the first diode D1 and the second diode D2 form a second connection end, the first diode D1 and the fourth diode D4 form a first connection end, the second diode D2 and the third diode D3 form a third connection end, and the third diode D3 and the fourth diode D4 form a fourth connection end. The first connection end is connected to one end of the secondary side of the first transformer, the third connection end is connected to the other end of the secondary side of the first transformer, the second connection end and the fourth connection end are the output ends of the first power supply, and the output ends of the first power supply are connected in parallel with the capacitor C.

[0059] The second rectifier circuit includes four diodes connected in a loop, and the structure is the same as that of the first rectifier circuit, wherein the first diode D5 and the second diode D6 form a second connection end, the first diode D5 and the fourth diode D8 form a first connection end, the second diode D6 and the third diode D7 form a third connection end, and the third diode D7 and the fourth diode D8 form a fourth connection end. The first connection end is connected to one end of the secondary side of the second transformer, the third connection end is connected to the other end of the secondary side of the second transformer, the second connection end and the fourth connection end are the output ends of the second power supply.

[0060] In an embodiment, the PID negative feedback control circuit includes a first single-chip microcomputer (model TMS320F28035 module), which collects the output voltage signal of the second power supply through a circuit R, converts the signal into an analog voltage signal suitable for the voltage range of the first single-chip microcomputer through a signal conditioning circuit, inputs the conditioned analog voltage signal into the on-chip ADC module of the first single-chip microcomputer to complete digital-to-analog conversion, and outputs a control quantity based on the deviation of the current sampling value from the set target value through the internal PID control program of the first single-chip microcomputer, converts the control quantity into a pulse width modulation signal through the EPWM module of the first single-chip microcomputer, and applies the pulse width modulation signal to the switching tube of the second power supply to dynamically adjust the on / off time of the switching tube.

[0061] The PID negative feedback control circuit is added to the second power supply. After the second power supply outputs high-voltage direct current, the output voltage signal is first collected in real time by a high-precision sampling circuit, i.e., a resistor R, and converted into a voltage range suitable for the first single-chip microcomputer through a signal conditioning circuit. Then, the conditioned analog voltage signal is input into the on-chip ADC module of the first single-chip microcomputer to complete digital-to-analog conversion and obtain a digital quantity for calculation. The first single-chip microcomputer internally pre-stores a PID control algorithm program. Based on the deviation of the current sampling value from the set target value, proportional, integral, and differential operations are sequentially performed. The proportional term directly reflects the error size to quickly respond to the deviation, the integral term accumulates historical errors to eliminate steady-state errors, and the differential term predicts the error trend to suppress overshoot. Finally, the first single-chip microcomputer outputs a control quantity through the PID negative feedback control circuit. The control quantity is converted into a pulse width modulation signal through the EPWM module (enhanced pulse width modulation) of the first single-chip microcomputer, applied to the switching tube of the second power supply, and dynamically adjusted in terms of on / off time to change the size of the output voltage. When the output voltage deviates from the set value due to load changes or external disturbances, the above-mentioned closed-loop process of sampling, calculation, and control will be repeatedly executed until the output voltage stabilizes within the set range, achieving high-precision voltage regulation. The control frequency is 20 KHz, which can meet the requirement of maintaining the stability of the output voltage.

[0062] The synchronous signal receiving circuit includes a second single-chip microcomputer and a power switch. The power switch is connected between the output end of the second power supply and the transmitter, and the control end of the power switch is connected to the second single-chip microcomputer. After receiving the synchronous signal of the transmitter, the second single-chip microcomputer outputs a control signal to control the power switch to turn on and turn off, thereby reducing the impact of power noise on the receiver.

[0063] The synchronous signal receiving circuit also uses TMS320F28035 to realize related functions. After the transmitter's synchronous signal is transmitted to the second power supply, the second single-chip microcomputer receives it. After receiving the signal, the second single-chip microcomputer turns on and turns off through the synchronous signal judgment and realizes it through the CAN communication instruction. When turning on, the second single-chip microcomputer receives the turn-on instruction and outputs it to the power switch to realize the start-up. When turning off, it is realized through the CAN instruction.

[0064] The CAN control module comprises a third single-chip microcomputer and a CAN bus, the third single-chip microcomputer communicates with the upper computer, the upper computer obtains the transmitting current data from the transmitter, and the third single-chip microcomputer controls the conduction and the closing of the switch tube of the second power supply according to the transmitting current data through the CAN bus.

[0065] The CAN control module uses a TMS320F28035 module to realize the communication between the upper computer and the power supply system. The upper computer realizes the communication between the two through a USB-to-CAN converter. The upper computer obtains the transmitting current data from the transmitter, and realizes the control of the output voltage of the second power supply according to the collected current data by sending the instructions agreed with the CAN control module. When the instructions stop for more than a certain time, the CAN control module controls the switch tube of the second power supply, realizes the automatic shutdown of the second power supply, and the second power supply continues to work after the next instruction comes. At this time, the first power supply has no effect on the second power supply.

[0066] The CAN control module is added in the second power supply to realize the real-time control of the output voltage, and the CAN bus is used to realize the communication between the upper computer and the CAN control module. The upper computer sends the set instructions through a USB-to-CAN adapter to control the output voltage of the second power supply, and can read the transmitting current information from the transmitter by using the instructions.

[0067] In an embodiment, the CAN control module, the synchronous signal receiving circuit and the PID negative feedback control circuit are integrated with the second power supply, the length of the circuit is reduced, the interference between the circuits is avoided, and the normal work of the power supply is avoided. At the same time, the PCB board is strengthened and heat dissipated, a cooling fan is added, and a cooling fin is added to the frequently opened and closed switch tube, so that the heat inside the power supply is not too high, and the internal components of the power supply are not caused by the high temperature. Heat breakdown leads to the failure of the power supply to work normally. The second power supply is externally provided with a metal shell to isolate the interference of the power supply to the outside and reduce the interference of the external environment to the power supply.

[0068] The first power supply and the second power supply are integrated and assembled by using an integrated metal shell, the two power supply modules are electrically connected by using a customized thick shielding cable, the thick shielding cable adopts a twisted shielding structure, the high-frequency transmission interference between the stages is effectively reduced, the overall structure design considers portability, installation convenience and structural durability, ensures that the equipment can still reliably operate in complex and harsh environments such as high temperature, high humidity and strong vibration, and meets the use requirements of field operation or emergency exploration scenes.

[0069] In order to solve the control performance bottleneck problem caused by the mutual coupling of high-precision acquisition of the synchronization signal in the transmitter and dynamic control of the power supply, three single-chip microcomputers are used in the application, the first single-chip microcomputer is located in the PID negative feedback control circuit, the second single-chip microcomputer is located in the synchronization signal receiving circuit, and the third single-chip microcomputer is located in the CAN control module, the first single-chip microcomputer is configured as a closed-loop power control unit, by real-time sampling of the key parameters of the power output end, running a digital proportional-integral-derivative control algorithm, dynamically calculating the optimal adjustment amount, and driving the MOSFET, forming a closed-loop negative feedback control loop, thereby realizing high stability, fast response and low ripple control of the power output voltage.

[0070] The second single-chip microcomputer is configured as a synchronization signal processing unit, which is used for high-speed capture, accurate measurement and interpretation of the synchronization reference signal generated by the transmitter, and provides a strict timing reference.

[0071] The third single-chip microcomputer is responsible for realizing CAN communication, realizing communication between the upper computer and the power supply system, and realizing the purpose of adjustable output voltage. This three single-chip microcomputer parallel processing architecture effectively isolates the high real-time synchronization task and the computationally intensive PID control task, avoids resource conflict risks, and significantly improves the overall control response speed, synchronization accuracy and power stability of the system.

[0072] The application discloses an intermittent synchronous double-stage high-voltage source system for aviation electromagnetic detection, wherein 28V power output from a helicopter flows into a first-stage power supply, enters a boost circuit after a first protection circuit of the first-stage power supply, is converted into alternating current after parallel shunting of a first switching device and then is turned on, is converted into direct current after boost output of a first transformer, and then enters a first rectifier circuit to output 310-320V first high-voltage direct current.

[0073] The first high-voltage direct current is boosted by an LLC resonant boost circuit of a second-stage power supply and is converted into second high-voltage direct current of a required level.

[0074] According to an instruction of the upper computer, a switching tube of the second-stage power supply is adjusted to realize adjustment of the second high-voltage direct current.

[0075] The second high-voltage direct current is collected, a control amount is output by a PID negative feedback control circuit based on a deviation between a current sampling value and a set target value, and the control amount is used to control a duty cycle of a driving waveform of the switching tube of the second-stage power supply.

[0076] After receiving a synchronization signal of a transmitter, a synchronization signal receiving circuit outputs a control signal according to the synchronization signal, and the control signal is used to control opening and closing of a power supply switch.

[0077] In order to realize high-voltage stable output of the power supply, voltage adjustable at any time, synchronous work of the transmitter and the high-voltage source system, the application uses two-stage power supply, CAN bus transmission, synchronous signal receiving and other modules. When the helicopter aviation transient electromagnetic transmitter works normally, the power supply realizes synchronous work of the transmitter and the power supply by receiving the synchronous signal of the transmitter; the high-voltage source system structure is two-stage, the first stage is push-pull structure, and the second stage power supply provides starting voltage; the second stage power supply is LLC resonant boost, and the voltage is raised to the highest position 750V. Two power supplies are integrated in a power supply box, so that the height integration is convenient for installation and carrying. The second stage power supply has PID voltage negative feedback regulation to ensure stable output voltage; CAN bus communication makes the output voltage adjustable at any time. The power supply voltage is improved, the transmitter magnetic moment can be increased, the interference to the receiver is reduced, and the foundation for the aviation electromagnetic detection system to detect deep areas is laid.

[0078] The above only describes the preferred embodiments of the application and is not used to limit the application, and any modification, equivalent replacement and improvement made within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. An intermittent synchronous dual-stage high-voltage source system for airborne electromagnetic prospecting, characterized in that, The application relates to a high-voltage DC power supply for a helicopter, which comprises the following parts: a first-stage power supply which converts input low-voltage DC power into first high-voltage DC power to supply power to a second-stage power supply; the second-stage power supply which raises the first high-voltage DC power to second high-voltage DC power of a required level; a PID negative feedback control circuit which detects the output voltage of the second-stage power supply by measurement and adjusts the output voltage of the second-stage power supply through the relationship between the output voltage and the input voltage of the first-stage power supply; the PID negative feedback control circuit comprises a first single-chip microcomputer, the output voltage signal of the second-stage power supply is collected through a circuit R, and the signal is converted into an analog voltage signal in a voltage range suitable for the first single-chip microcomputer through a signal conditioning circuit; the analog voltage signal after conditioning is input into an on-chip ADC module of the first single-chip microcomputer to complete digital-to-analog conversion; based on the deviation between the current sampling value and the set target value, the first single-chip microcomputer outputs a control quantity through an internal PID control program, the control quantity is converted into a pulse width modulation signal through an EPWM module of the first single-chip microcomputer, and the pulse width modulation signal acts on a switching tube of the second-stage power supply to dynamically adjust the on / off time of the switching tube; a synchronous signal receiving circuit which controls the output of the second-stage power supply to be synchronized with a transmitter by receiving the synchronous signal of the transmitter; the synchronous signal receiving circuit comprises a second single-chip microcomputer and a power switch, the power switch is connected between the output end of the second-stage power supply and the transmitter, the control end of the power switch is connected to the second single-chip microcomputer, and the second single-chip microcomputer outputs a control signal to control the power switch to be turned on and turned off according to the synchronous signal after receiving the synchronous signal of the transmitter; a CAN control module which adjusts the level of the output voltage of the second-stage power supply by receiving the instruction of an upper computer; the CAN control module comprises a third single-chip microcomputer and a CAN bus, the third single-chip microcomputer communicates with the upper computer, the upper computer obtains the transmission current data from the transmitter, and the third single-chip microcomputer controls the on and off of the switching tube of the second-stage power supply through the CAN bus according to the transmission current data.

2. The system according to claim 1, wherein, The first-stage power supply comprises: a boost circuit which comprises a first transformer and first switching devices in a push-pull structure, the first switching devices comprise switching tubes Q1, Q2, Q3 and Q4, the drain of the switching tube Q1 is connected to the drain of the switching tube Q3 and connected to one end of the primary side of the first transformer, the source of the switching tube Q1 is connected to the drain of the switching tube Q2, the source of the switching tube Q3 is connected to the drain of the switching tube Q4, the source of the switching tube Q4 is connected to the source of the switching tube Q2 and connected to the other end of the primary side of the first transformer, and the source of the switching tube Q1 and the source of the switching tube Q3 are both connected to the negative pole of the helicopter power supply; a first protection circuit which is connected to the positive pole of the power supply at one end and connected to the intermediate tap of the first transformer at the other end; a first rectifier circuit which adopts a bridge rectifier circuit and is connected to the secondary side of the first transformer through two input ends, one positive pole end and one negative pole end serving as the output end of the first-stage power supply.

3. The system according to claim 1, wherein the system is characterized by: The second-stage power supply comprises: The LLC resonant boost circuit comprises four groups of parallel switch tubes and a second transformer, wherein the middle tap of the first group of switch tubes is connected to the first end of a resonant inductor Lr, the second end of the resonant inductor Lr is connected to the first end of the primary side of the second transformer, the middle tap of the third group of switch tubes is connected to the first end of a resonant capacitor Cr, and the second end of the resonant capacitor Cr is connected to the second end of the primary side of the second transformer; the primary side of the second transformer is connected in parallel with a transformer leakage inductance Lm; The second rectifier circuit adopts a bridge rectifier circuit and is connected to the secondary side of the second transformer through two input ends, and a positive electrode end and a negative electrode end are used as the output ends of the second-stage power supply; the positive electrode end and the negative electrode end are connected in parallel with a capacitor C1 and a resistor R.

4. The system according to claim 2, wherein, The first rectifier circuit comprises four diodes connected in series, wherein the second connection end is between the first diode D1 and the second diode D2, the first connection end is between the first diode D1 and the fourth diode D4, the third connection end is between the second diode D2 and the third diode D3, the fourth connection end is between the third diode D3 and the fourth diode D4, the first connection end is connected to one end of the secondary side of the first transformer, the third connection end is connected to the other end of the secondary side of the first transformer, and the second connection end and the fourth connection end are used as the output ends of the first-stage power supply.

5. The system according to claim 3, wherein, The second rectifier circuit comprises four diodes connected in series, wherein the second connection end is between the first diode D5 and the second diode D6, the first connection end is between the first diode D5 and the fourth diode D8, the third connection end is between the second diode D6 and the third diode D7, the fourth connection end is between the third diode D7 and the fourth diode D8, the first connection end is connected to one end of the secondary side of the second transformer, the third connection end is connected to the other end of the secondary side of the second transformer, and the second connection end and the fourth connection end are used as the output ends of the second-stage power supply.

6. The system according to any one of claims 1-5, wherein the system is an intermittent synchronous dual-stage high-voltage source system for airborne electromagnetic prospecting, characterized in that, The working method of the intermittent synchronous double-stage high-voltage source system for airborne electromagnetic detection comprises: The 28V power supply output from the helicopter flows into the first-stage power supply, enters the boost circuit after passing through the first protection circuit of the first-stage power supply, is converted into alternating current after passing through the parallel shunt of the first switch device, and is output as 310-320V first high-voltage direct current after passing through the first rectifier circuit; The first high-voltage direct current is boosted by the LLC resonant boost circuit of the second-stage power supply and is converted into second high-voltage direct current of a required level; According to the output voltage level requirement set by the upper computer, the switch tube of the second-stage power supply is adjusted to adjust the level of the second high-voltage direct current; Based on the deviation between the current sampling value and the set target value, the PID negative feedback control circuit outputs a control quantity to act on the switch tube of the second-stage power supply to control the duty cycle of the drive waveform.

7. The system according to claim 6, wherein, Further comprising: The synchronous signal receiving circuit outputs a control signal according to the synchronous signal of the transmitter to act on the power supply switch to control the opening and closing of the power supply switch.

Images