SPWM power conversion and closed loop control circuit for large buried depth cable detector transmitter

Abstract

The utility model discloses a kind of SPWM power conversion and closed-loop control circuit for large buried depth cable detector transmitter, including SPWM logic input circuit, it is accessed drive circuit, drive circuit is accessed the first signal interface of main control panel by output source test circuit;The second signal interface of main control panel accesses SPWM logic input circuit;The output end of drive circuit is also accessed current acquisition circuit and output voltage detection circuit respectively, current acquisition circuit is accessed the ADC acquisition module of main control panel by output current detection circuit, output voltage detection module also accesses the ADC acquisition module of main control panel. Total control power supply is passed through switch-on-off circuit, relay switches power main loop, SPWM logic input circuit and drive circuit cooperate with direct current into the high-frequency pulse alternating current of adaptation detection, while current acquisition, output current / voltage detection circuit real-time feedback parameter to realize closed-loop regulation, discharge circuit and overcurrent / overvoltage protection mechanism can avoid circuit damage when failure.

Description

Technical Field

[0001] This utility model relates to a transmitter power output circuit, and more specifically, it relates to an SPWM power conversion and closed-loop control circuit for a transmitter of a deep-buried cable detector. Background Technology

[0002] Cable detector transmitters are cable fault detection devices that integrate path detection, burial depth measurement, cable identification, and fault location functions. However, for urban cables buried at great depths, detection accuracy is affected, hindering cable fault location. Furthermore, because the transmitter outputs high-frequency pulsed AC power, it may further damage the fault circuit, further complicating fault diagnosis in underground cable networks. Therefore, it is necessary to further research and improve the internal circuit structure of current cable detector transmitters, considering the truly deep burial of cables and the controllability of high-frequency pulsed AC power. Utility Model Content

[0003] One of the objectives of this invention is to address the aforementioned shortcomings by providing an SPWM power conversion and closed-loop control circuit for a deep-buried cable detector transmitter. This aims to solve the technical problems of existing cable detector transmitters, such as difficulty in controlling the output high-frequency pulse AC power, which can easily lead to circuit failure and damage. Additionally, the circuits are not accurate enough for detecting deeply buried cables.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: This utility model provides an SPWM power conversion and closed-loop control circuit for a transmitter of a deep-buried cable detector, characterized by: an SPWM logic input circuit connected to a drive circuit, the drive circuit being connected to the first signal interface of the main control board via an output source test circuit; the second signal interface of the main control board also being connected to the SPWM logic input circuit; the SPWM logic input circuit receiving the SPWM signal output from the main control board and outputting it to the drive circuit; the output terminal of the drive circuit being connected to a current acquisition circuit and an output voltage detection circuit respectively, the current acquisition circuit being connected to the ADC acquisition module of the main control board via the output current detection circuit, and the output voltage detection module also being connected to the ADC acquisition module of the main control board; the output terminal of the drive circuit being connected to a discharge control circuit, the discharge control circuit controlling the on / off state of the MOS transistor through a cascaded transistor amplification to adjust the values ​​of the discharge output current and voltage; the current acquisition circuit sensing the output current through a current transformer, then detecting the current value in real time via the current detection circuit and outputting it to the ADC acquisition module of the main control board; the output voltage detection circuit calculating the current output voltage value and transmitting it to the ADC acquisition module of the main control board.

[0005] As a preferred embodiment, a further technical solution is as follows: the output source test circuit includes an output source current test circuit and an output source voltage test circuit, both of which are connected to the first signal interface and drive circuit of the main control board; the output source current test circuit is used to output a CT_OUT_P detection signal to the main control board; the output source voltage test circuit is used to output a V_P detection signal to the main control board.

[0006] A further technical solution is that the SPWM logic input circuit is also connected to the regulated power supply circuit through a power-on / off circuit, and the power-on / off circuit is used to control the regulated power supply circuit to supply power to each circuit under the control of a trigger signal.

[0007] A further technical solution is that the driving circuit is also connected to a relay control circuit, which is used to output driving signals to control the on / off state of multiple relays.

[0008] A further technical solution is that the main control board also includes a microcontroller processing module, which receives digital signals from the ADC acquisition module and generates an SPWM signal to be transmitted to the SPWM logic input circuit. It also receives CT_OUT_P detection signals and V_P detection signals. The CT_OUT_P detection signal is output by the output source current test circuit, and the V_P detection signal is output by the output source voltage test circuit.

[0009] Compared with existing technologies, one of the beneficial effects of this utility model is that by controlling the main power supply through the power-on / off circuit, switching the main power circuit through relays, and coordinating the SPWM logic input circuit and the drive circuit to convert DC power into high-frequency pulse AC power suitable for detection, while the current acquisition and output current / voltage detection circuits provide real-time feedback parameters to achieve closed-loop regulation, and the discharge circuit and overcurrent / overvoltage protection mechanism can prevent circuit damage in case of faults; it is specifically designed for urban underground buried cable path detection, fault location (such as short circuit and open circuit troubleshooting), insulation status and continuity inspection of old cables, which can ensure the stable operation of the detector, ensure the accuracy of cable burial depth and fault point location, and prevent the risk of high voltage residual electric shock and equipment burnout through multiple protections, ensuring operation and equipment safety. Attached Figure Description

[0010] Figure 1 This is a schematic block diagram illustrating one embodiment of the present invention.

[0011] Figure 2 This is a circuit diagram illustrating the SPWM logic input circuit in one embodiment of the present invention.

[0012] Figure 3This is a circuit diagram illustrating the driving circuit in one embodiment of the present invention.

[0013] Figure 4 This is a circuit diagram illustrating the output source current testing circuit in one embodiment of the present invention.

[0014] Figure 5 The circuit diagram is provided to illustrate an embodiment of the output source voltage testing circuit of this utility model. Figure 6 This is a circuit diagram illustrating the current acquisition circuit in one embodiment of the present invention.

[0015] Figure 7 This is a circuit diagram illustrating the output current detection circuit in one embodiment of the present invention.

[0016] Figure 8 This is a circuit diagram illustrating the output voltage detection circuit in one embodiment of the present invention.

[0017] Figure 9 This is a circuit diagram illustrating the discharge control circuit in one embodiment of the present invention.

[0018] Figure 10 This is a schematic diagram of the main control board signal structure in one embodiment of the present invention.

[0019] Figure 11 This is a circuit diagram illustrating the power-on / off circuit in one embodiment of the present invention.

[0020] Figure 12 This is a circuit diagram illustrating a voltage regulator circuit in one embodiment of the present invention.

[0021] Figure 13 This is a circuit diagram illustrating a relay control circuit in one embodiment of the present invention. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings.

[0023] refer to Figure 1As shown in the figure, one embodiment of this utility model is an SPWM power conversion and closed-loop control circuit for a transmitter of a deep-buried cable detector. The circuit of this embodiment includes an SPWM logic input circuit, which is connected to a drive circuit. The drive circuit is connected to the first signal interface of the main control board through an output source test circuit. Preferably, the aforementioned output source test circuit includes an output source current test circuit and an output source voltage test circuit, both of which are connected to the first signal interface of the main control board and the drive circuit. Specifically, the output source current test circuit is used to output a CT_OUT_P detection signal to the main control board; the output source voltage test circuit is used to output a V_P detection signal to the main control board.

[0024] Meanwhile, the second signal interface of the main control board is also connected to the SPWM logic input circuit, thus forming a closed-loop control. The SPWM logic input circuit receives the SPWM signal output from the main control board and outputs it to the drive circuit. The output of the aforementioned drive circuit is also connected to a current acquisition circuit and an output voltage detection circuit. The current acquisition circuit is connected to the ADC acquisition module of the main control board through the output current detection circuit, and the output voltage detection module is also connected to the ADC acquisition module of the main control board. The output of the drive circuit is also connected to a discharge control circuit. The discharge control circuit controls the switching of the MOSFET through cascaded transistor amplification, adjusting the values ​​of the discharge output current and voltage. The current acquisition circuit senses the output current through a current transformer, and then outputs the current value to the ADC acquisition module of the main control board after real-time detection by the current detection circuit. The output voltage detection circuit calculates the current output voltage value and transmits it to the ADC acquisition module of the main control board.

[0025] In this embodiment, the main power supply is controlled by the power-on / off circuit, the main power circuit is switched by the relay, and the SPWM logic input circuit and the drive circuit work together to convert DC power into high-frequency pulse AC power suitable for detection. At the same time, the current acquisition and output current / voltage detection circuits provide real-time feedback parameters to achieve closed-loop regulation. The discharge circuit and overcurrent / overvoltage protection mechanism can prevent circuit damage in case of fault. It is specially designed for urban underground buried cable path detection, fault location (such as short circuit and open circuit troubleshooting), insulation status and continuity inspection of old cables. It can ensure the stable operation of the detector, ensure the accuracy of cable burial depth and fault point location, and prevent the risk of high voltage residual electric shock and equipment burnout through multiple protections, ensuring operation and equipment safety.

[0026] Based on the above embodiments, furthermore, as Figure 1As shown, the aforementioned SPWM logic input circuit is also connected to a regulated power supply circuit via a power-on / off circuit. The function of the aforementioned power-on / off circuit is to be controlled by a trigger signal to turn on the regulated power supply circuit to supply power to each circuit. Simultaneously, for convenient control of the relays, the aforementioned drive circuit is also connected to a relay control circuit. The function of the relay control circuit is to output drive signals to control the on / off state of multiple relays. As... Figure 1 As shown, the aforementioned main control board includes a microcontroller processing module, which is used to receive digital signals from the ADC acquisition module and then generate an SPWM signal to be transmitted to the SPWM logic input circuit. At the same time, it receives the CT_OUT_P detection signal and the V_P detection signal. As mentioned above, the CT_OUT_P detection signal is the output of the output source current test circuit, and the V_P detection signal is the output of the output source voltage test circuit.

[0027] All the circuits described above are based on existing finished circuits, either transplanted or improved. Those skilled in the art should understand that, within the circuit structure of the above embodiments, each existing circuit plays its respective role, thereby achieving the technical objective of this utility model. However, to facilitate a better understanding of the technical concept of this utility model, the inventors have also provided a brief explanation of the aforementioned circuit structures and principles, with specific comparisons provided. Figure 1 As shown, where: refer to Figure 2 As shown, the SPWM logic input circuit limits the current of the SPWM+ and SPWM- input signals through D10, D13 (1N4448W) ​​and R23, R25 (100Ω). After filtering by C28 and C30 (47pF), the signals are clamped and protected by D12 and D14 (1N4448W), and finally outputs stable SPWM2+ and SPWM2- logic signals, realizing current limiting, filtering and overvoltage protection of the SPWM input.

[0028] refer to Figure 3 As shown, the drive circuit uses IR2110S (U10, U13) as the core drive chip. After receiving SPWM2+ / - and other logic signals, it outputs high and low side drive signals to control the on / off state of IXFH38N20 MOSFETs (Q4, Q5, Q6, Q8). At the same time, it uses IN4148 diodes (D20, D27, etc.) for current limiting, MUR1540 diodes for freewheeling, and capacitors (C25, C41, etc.) for filtering and voltage regulation. It is paired with SN74121DR (U15) to process check_v, Control Output and other signals to achieve logic control. At the end, GDRK relays, inductors (L6 / L7) ​​and TVS diodes (D34) are used for surge and path protection, finally realizing stable conversion and safe output of SPWM signals to power stage drive.

[0029] refer to Figure 4 As shown, the output source current test circuit converts the output source current into a sampling voltage through R34 (0.2R 1%). After the weak voltage signal is amplified by operational amplifier U8A, it is conditioned by operational amplifier U9B, and finally filtered by C33, overvoltage protected by SMBJ5.0A (D16), and clamped and stabilized by D19, outputting a +ADJ_I_ADC detection signal to realize the sampling, amplification, and protective detection of the output source current (R31, R32, etc. in the circuit are uninstalled components).

[0030] refer to Figure 5 As shown, the output source voltage test circuit first divides the VCC_ADJ_P voltage through resistors R43, R44, and R46, and then filters it through C38. Subsequently, the processed signal is input to the OP07CDR operational amplifier for voltage conditioning. The output of the operational amplifier is filtered again through R45 and C39, and then stabilized by overvoltage protection of SMBJ5.0A (D26) and clamping by BAV99 (D32). Finally, the +ADJ_V_ADC1 detection signal is output, realizing the voltage division, filtering, conditioning, and protective detection of the VCC_ADJ_P voltage.

[0031] refer to Figure 6 As shown, the current acquisition circuit uses a ZMCT103C current transformer (CT1) to acquire the line current of WF_8, which is then converted into a Current test1 / 2 voltage signal via sampling resistors R47 / R49 / R50. Simultaneously, the Relay ON signal controls transistor Q3 and relay K3 to switch the sampling path of R36 / R39 (RX21-20W 3R), and D24 (P6KE170CA) provides surge protection. Finally, the output voltage1 and output voltage2 are adjusted by potentiometers W1 / W3 to realize the functions of current sampling, path switching, and voltage signal output.

[0032] refer to Figure 7As shown, the output current detection circuit uses an LM358 operational amplifier (U7A) as its core. Current test1 and Current test2 are conditioned by resistors R21 and R17 before being input to the operational amplifier. The current signal is amplified by an amplification circuit composed of R16, and then processed by a filter network composed of R18, R19, R20 and C24, C25, and C27. At the same time, the U7B branch of the LM358, combined with components such as R26, C31, R24, and C29, implements power conditioning. In the circuit, R15 (0.05R) is used for common ground isolation during the debugging process, and D9 (SMBJ5.0A) and D11 (BAV99) provide overvoltage protection. Finally, the CT_OUT_P signal is output. Under the power supply of AGND, VCC+12V, and VCC-12V, the output current detection, amplification, filtering, and overvoltage protection functions are completed.

[0033] refer to Figure 8 As shown, the output voltage detection circuit uses LM358 (U16A, U16B) as its core, powered by ±12V. The signal Output Voltage1 is filtered by capacitors and differentially amplified, then filtered by R75 / R76 and C52 / C54, supplemented by D46 (SMBJ5.0A) overvoltage protection and D47 (BAV99) clamping, and finally outputs V_P detection signal to realize the sampling, conditioning and protective detection of output voltage.

[0034] refer to Figure 9 As shown, the discharge control circuit uses the SEPI_LOAD_EN signal as the control input, which drives T2 (9013 transistor) to conduct through R60, thereby triggering T1 (9012 transistor) to conduct, and finally controlling the on / off state of Q7 (IRF640N MOSFET). When Q7 conducts, the voltage at the VCC_ADJ_P terminal will form a discharge circuit with Q7 through R55 (RX21-15W 2K), thus realizing the discharge path switching function controlled by the SEPI_LOAD_EN signal.

[0035] Regarding the signal interfaces of the main control board, such as... Figure 10 As shown, the circuit diagram of the voltage regulator circuit is as follows: Figure 12 As shown.

[0036] refer to Figure 11As shown, the power-on / off circuit first uses D3 (SS16) to prevent reverse connection of the power supply, and D1 (P6KE51CA) and C5 to suppress and filter surges. Then, the ON KEY button and the MCU ON signal drive Q2 (9013) through D2 and D4 (1N4148), which in turn controls Q1 (IRF9540N P-channel MOSFET) to achieve self-locking of power on and off. At the same time, the button status is fed back through MCU ONFB. Finally, after Q1 is turned on, it outputs PWR_2, which is filtered by C1 and sampled by R3 (0.05R), thus realizing power-on / off control with reverse connection protection, surge protection and status feedback.

[0037] refer to Figure 13 As shown, the relay control circuit uses U14 (74HC595D) to convert serial input (Relay 273CLR / CLK, Relay 4051 DA / CK / LC matched by a 51R resistor) to parallel data, and then the 8 outputs of U12 (TPIC6B273DWR) drive the relays. Among them, C42, C44, C46, ​​and C47 are filter capacitors to stabilize the power supply, and R65 pull-up resistor ensures the signal level. Finally, it realizes the serial control and parallel drive of multiple relays, providing reliable relay switching logic for the system.

[0038] In addition to the above, it should be noted that the terms "one embodiment," "another embodiment," and "embodiment" used in this specification refer to specific features, structures, or characteristics described in connection with that embodiment, which are included in at least one embodiment described in the general description of this application. The appearance of the same expression in multiple places in the specification does not necessarily refer to the same embodiment. Furthermore, when a specific feature, structure, or characteristic is described in connection with any embodiment, the intention is to suggest that implementing such a feature, structure, or characteristic in conjunction with other embodiments also falls within the scope of this utility model.

[0039] Although the present invention has been described herein with reference to several illustrative embodiments, it should be understood that many other modifications and implementations can be devised by those skilled in the art, which will fall within the scope and spirit of the principles disclosed herein. More specifically, various variations and modifications can be made to the components and / or layout of the subject matter combination within the scope of the disclosure, drawings, and claims. Besides variations and modifications to the components and / or layout, other uses will be apparent to those skilled in the art.

Claims

1. An SPWM power conversion and closed-loop control circuit for a transmitter of a deep-buried cable detector, characterized in that: It includes an SPWM logic input circuit, which is connected to a drive circuit. The drive circuit is connected to the first signal interface of the main control board through an output source test circuit. The second signal interface of the main control board is also connected to the SPWM logic input circuit. The SPWM logic input circuit is used to receive the SPWM signal output by the main control board and output it to the drive circuit. The output terminal of the drive circuit is also connected to a current acquisition circuit and an output voltage detection circuit respectively. The current acquisition circuit is connected to the ADC acquisition module of the main control board through the output current detection circuit, and the output voltage detection module is also connected to the ADC acquisition module of the main control board. The output of the driving circuit is also connected to a discharge control circuit, which is used to control the on / off state of the MOS transistor through cascaded transistor amplification, and adjust the values ​​of the discharge output current and voltage. The current acquisition circuit is used to sense the output current through the current transformer, and then the current value is detected in real time by the current detection circuit and output to the ADC acquisition module of the main control board. The output voltage detection circuit is used to calculate the current output voltage value and transmit it to the ADC acquisition module of the main control board.

2. The SPWM power conversion and closed-loop control circuit for the transmitter of a deep-buried cable detector according to claim 1, characterized in that: The output source test circuit includes an output source current test circuit and an output source voltage test circuit, both of which are connected to the first signal interface and drive circuit of the main control board. The output source current test circuit is used to output the CT_OUT_P detection signal to the main control board; the output source voltage test circuit is used to output the V_P detection signal to the main control board.

3. The SPWM power conversion and closed-loop control circuit for the transmitter of a deep-buried cable detector according to claim 1, characterized in that: The SPWM logic input circuit is also connected to the voltage regulator circuit through a power-on / off circuit. The power-on / off circuit is used to control the voltage regulator circuit to supply power to each circuit under the control of a trigger signal.

4. The SPWM power conversion and closed-loop control circuit for the transmitter of a deep-buried cable detector according to claim 1, characterized in that: The drive circuit is also connected to a relay control circuit, which outputs drive signals to control the on / off state of multiple relays.

5. The SPWM power conversion and closed-loop control circuit for the transmitter of a deep-buried cable detector according to claim 1, characterized in that: The main control board also includes a microcontroller processing module, which receives digital signals from the ADC acquisition module and generates an SPWM signal to be transmitted to the SPWM logic input circuit. It also receives the CT_OUT_P detection signal and the V_P detection signal. The CT_OUT_P detection signal is output by the output source current test circuit, and the V_P detection signal is output by the output source voltage test circuit.

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