Negative high voltage power supply and underground equipment

Abstract

The utility model discloses a negative high voltage power supply and underground equipment, and the power supply comprises a boost module group, the first input end of which is connected with the input end of a power supply; the drain electrode of the N-type MOS tube is connected with the second input end of the boost module; the first end of the sampling resistor is connected with the source electrode of the N-type MOS tube, and the second end of the sampling resistor is grounded; the first input end of the control module is connected with the output end of the boosting module, the second input end of the control module is connected with the first end of the sampling resistor, the output end of the control module is connected with the grid electrode of the N-type MOS tube, and the control module is used for collecting a direct current signal output by the output end of the boosting module; and the control module is used for receiving the DC signal output by the boost module, adjusting the duty ratio of the PWM signal input to the N-type MOS tube according to the voltage of the DC signal output by the boost module, enabling the boost module to output the DC signal of the target negative voltage value, collecting the sampling voltage of the sampling resistor, and controlling to turn off the N-type MOS tube when the sampling voltage is greater than a first preset voltage threshold.

Description

Technical Field

[0001] This utility model relates to the field of downhole equipment technology, and in particular to a negative high voltage power supply and downhole equipment. Background Technology

[0002] Well logging equipment is of great significance to oil exploration and development. Applying well logging equipment and technology to mines can effectively collect various physical information in the underground environment, such as force, heat, and nuclear information.

[0003] Due to the complex underground environment, it is necessary to ensure the safety of underground equipment under different operating conditions. Utility Model Content

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, one objective of this invention is to provide a negative high-voltage power supply that can provide a stable negative high-voltage DC signal to the load, while also being able to promptly disconnect the negative high-voltage power supply in the event of a short circuit in the load.

[0005] The second objective of this invention is to provide a downhole device.

[0006] To achieve the above objectives, a first aspect of this utility model provides a negative high-voltage power supply, comprising: a boost module, wherein a first input terminal of the boost module is connected to the input terminal of a power supply for boosting a DC signal of a first voltage value input from the power supply; an N-type MOSFET, the drain of which is connected to a second input terminal of the boost module; a sampling resistor, the first terminal of which is connected to the source of the N-type MOSFET, and the second terminal of which is grounded; and a control module, wherein a first input terminal of the control module is connected to the boost module. The output terminal of the boost module is connected, the second input terminal of the control module is connected to the first terminal of the sampling resistor, and the output terminal of the control module is connected to the gate of the N-type MOSFET. This is used to acquire the DC signal output from the boost module, adjust the duty cycle of the PWM signal input to the N-type MOSFET based on the voltage of the DC signal output from the boost module, causing the boost module to output a DC signal with a target negative voltage value, and acquire the sampling voltage of the sampling resistor. When the sampling voltage exceeds a first preset voltage threshold, the N-type MOSFET is turned off.

[0007] According to the embodiment of this utility model, the negative high voltage power supply adopts voltage and current dual feedback to control the output of the PWM signal. The duty cycle of the PWM signal is quickly adjusted at a fixed frequency to regulate the output voltage of the boost module, so that the negative high voltage power supply provides a stable negative high voltage DC signal to the load. At the same time, the negative high voltage power supply can be disconnected in time when a short circuit occurs in the load.

[0008] In addition, the negative high-voltage power supply proposed according to the above embodiments of this utility model may also have the following additional technical features:

[0009] In some examples, the control module includes: a feedback circuit, the input of which is connected to a first input of the control module, for acquiring the DC signal output from the boost module, converting the DC signal output from the boost module into a positive voltage DC signal, and reducing the positive voltage DC signal to a second voltage DC signal; and a switching chip, the FB terminal of which is connected to the output of the feedback circuit, the CS terminal of which is connected to a second input of the control module, and the output of which is connected to the output of the control module, for adjusting the duty cycle of the PWM signal input to the N-type MOSFET according to the second voltage DC signal, and acquiring the sampling voltage of the sampling resistor, and controlling the N-type MOSFET to be turned off when the sampling voltage is greater than a first preset voltage threshold.

[0010] In some examples, the switching chip is used to reduce the duty cycle of the PWM signal when the second voltage value is greater than a second preset voltage threshold, and to increase the duty cycle of the PWM signal when the second voltage value is less than the second preset voltage threshold.

[0011] In some examples, the switching chip is used to acquire the sampling voltage of the sampling resistor, use the comparator of the switching chip to determine whether the sampling voltage is greater than the first preset voltage threshold, and when the sampling voltage is greater than the first preset voltage threshold, output a low-level signal to turn off the N-type MOS transistor.

[0012] In some examples, the feedback circuit includes a first resistor, a first operational amplifier, and a second resistor. A first end of the first resistor is connected to the input of the feedback circuit, a second end of the first resistor is connected to the negative input of the first operational amplifier, the positive input of the first operational amplifier is grounded, the output of the first operational amplifier is connected to the output of the feedback circuit, and the output of the first operational amplifier is also connected to the negative input of the first operational amplifier through the second resistor.

[0013] In some examples, the boost module includes a transformer and a boost circuit, wherein a first input terminal of the transformer is connected to, a second input terminal of the transformer is connected to, a first output terminal of the transformer is connected to, a second output terminal of the transformer is grounded and connected to, a second input terminal of the boost circuit, and an output terminal of the boost circuit is connected to, the output terminal of the boost module.

[0014] In some examples, the boost circuit includes multiple sets of capacitors and diodes.

[0015] In some examples, the boost circuit includes a first capacitor, a first diode, a second capacitor, a second diode, a third capacitor, a third diode, a fourth capacitor, a fourth diode, a fifth capacitor, a fifth diode, a sixth capacitor, and a sixth diode. A first terminal of the first capacitor is connected to a first input terminal of the boost circuit. A second terminal of the first capacitor is connected to the anode of the first diode. The cathode of the first diode is connected to a second input terminal of the boost circuit. The cathode of the first diode is connected to the anode of the second diode through the second capacitor. The cathode of the second diode is connected to the anode of the third diode through the third capacitor. The third diode's cathode is connected to the second diode's anode. The third diode's cathode is connected to the fourth diode's anode through the fourth capacitor. The fourth diode's cathode is connected to the third diode's anode. The fourth diode's cathode is connected to the fifth diode's anode through the fifth capacitor. The fifth diode's cathode is connected to the fourth diode's anode. The fifth diode's cathode is connected to the sixth diode's anode through the sixth capacitor. The sixth diode's cathode is connected to the fifth diode's anode. The sixth diode's anode is connected to the output terminal of the boost circuit.

[0016] To achieve the above objectives, a second aspect of this utility model provides a downhole device including a negative high-voltage power supply as described in the first aspect of this utility model.

[0017] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] Figure 1 This is a circuit block diagram of a negative high-voltage power supply according to an embodiment of the present invention;

[0019] Figure 2 This is a circuit diagram of a feedback circuit according to an embodiment of the present invention;

[0020] Figure 3 This is a circuit diagram of a boost circuit according to an embodiment of the present invention;

[0021] Figure 4 This is a circuit diagram of a boost circuit according to a specific embodiment of the present invention;

[0022] Figure 5 This is a schematic diagram of a downhole device according to an embodiment of the present invention. Attached image description:

[0024] 100. Negative high voltage power supply; 10. Boost module; 11. Transformer; 12. Transformer; 20. Control module; 21. Feedback circuit; U1. Switching chip; A1. First operational amplifier; Q1. MOSFET; R0. Sampling resistor; R1. First resistor; R2. Second resistor; C1. First capacitor; C2. Second capacitor; C3. Third capacitor; C4. Fourth capacitor; C5. Fifth capacitor; C6. Sixth capacitor; D1. First diode; D2. Second diode; D3. Third diode; D4. Fourth diode; D5. Fifth diode; D6. Sixth diode; 1000. Downhole equipment. Detailed Implementation

[0025] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.

[0026] The negative high-voltage power supply and downhole equipment of this utility model embodiment will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0027] Figure 1 This is a circuit block diagram of the negative high-voltage power supply according to an embodiment of this utility model. (See diagram below.) Figure 1 As shown, the negative high-voltage power supply 100 may include:

[0028] The boost module 10 has its first input terminal connected to the input terminal of the power supply for boosting the DC signal of the first voltage value input from the power supply.

[0029] N-type MOSFET Q1, the drain of N-type MOSFET Q1 is connected to the second input terminal of boost module 10;

[0030] The sampling resistor R0 is connected to the source of the N-type MOSFET Q1 at its first end and grounded at its second end.

[0031] The control module 20 has its first input terminal connected to the output terminal of the boost module 10, its second input terminal connected to the first terminal of the sampling resistor R0, and its output terminal connected to the gate of the N-type MOSFET Q1. This is used to acquire the DC signal output from the boost module 10, adjust the duty cycle of the PWM signal input to the N-type MOSFET Q1 based on the voltage of the DC signal output from the boost module 10, so that the boost module 10 outputs a DC signal with a target negative voltage value, and acquire the sampling voltage of the sampling resistor R0. When the sampling voltage is greater than a first preset voltage threshold, the N-type MOSFET Q1 is turned off.

[0032] The negative high-voltage power supply 100 of this utility model embodiment is used in the downhole equipment 1000 and can provide power to the near-bit measurement while drilling system (load) of the downhole equipment 100.

[0033] The negative high voltage power supply 100 of this utility model adopts the principle of single-tube flyback and bootstrap voltage boost. According to the voltage and current dual feedback control PWM signal, the negative high voltage power supply 100 outputs a stable DC signal with a target negative voltage value, and disconnects the negative high voltage power supply 100 in time when a short circuit occurs in the load.

[0034] To ensure that the boost module 10 outputs a stable DC signal with a target negative voltage value, the first input terminal of the boost module 10 receives a DC signal with a first voltage value input from the power supply, and the second input terminal of the boost module 10 is connected to the drain of the N-type MOSFET Q1. The boost module 10 boosts the DC signal with the first voltage value input from the power supply and outputs the boosted DC signal. The control module 20 acquires the boosted DC signal output by the boost module 10 and adjusts the duty cycle of the PWM signal input to the gate of the N-type MOSFET Q1 according to the voltage of the boosted DC signal, so that the boost module 10 outputs a DC signal with a stable target negative voltage value.

[0035] To prevent short circuits in the system, the negative high-voltage power supply 100 of this invention is equipped with a sampling resistor R0. The first terminal of the sampling resistor R0 is connected to the source of the N-type MOSFET Q1, and the second terminal of the sampling resistor R0 is grounded. The sampling resistor R0 is used to monitor and provide feedback on the current on the primary side of the power supply. The control module 20 acquires the sampling voltage of the sampling resistor R0, and when the sampling voltage is greater than a first preset voltage threshold, it outputs a low-level control to turn off the N-type MOSFET Q1, thereby controlling the negative high-voltage power supply 100 to stop supplying power to the load.

[0036] In one embodiment of this utility model, such as Figure 1 As shown, the control module 20 may include:

[0037] Feedback circuit 21, the input terminal of feedback circuit 21 is connected to the first input terminal of control module 20, and is used to collect the DC signal output by the output terminal of boost module 10, convert the DC signal output by boost module 10 into a positive voltage DC signal, and reduce the positive voltage DC signal into a second voltage DC signal.

[0038] Switching chip U1 has its FB terminal connected to the output terminal of feedback circuit 21, its CS terminal connected to the second input terminal of control module 20, and its output terminal connected to the output terminal of control module 20. It is used to adjust the duty cycle of the PWM signal input to N-type MOSFET Q1 according to the DC signal of the second voltage value, and to collect the sampling voltage of sampling resistor R0. When the sampling voltage is greater than the first preset voltage threshold, it controls the N-type MOSFET Q1 to be turned off.

[0039] Specifically, the control module 20 uses the feedback circuit 21 to collect the DC signal output from the output terminal of the boost module 10. The feedback circuit 21 converts the DC signal output from the boost module 10 into a positive voltage DC signal, and at the same time reduces the positive voltage DC signal to a second voltage DC signal proportionally, so that the switching chip U1 can adjust the duty cycle of the PWM signal input to the N-type MOS transistor Q1 according to the second voltage DC signal.

[0040] The FB pin (feedback pin) of the switching chip U1 is connected to a DC signal of a second voltage value. An error amplifier adjusts the duty cycle of the PWM signal input to the N-type MOSFET Q1 based on this DC signal, maintaining the DC signal output by the boost module 10 at the target negative voltage value. The control module achieves stability of the negative high-voltage power supply output by controlling the power supply voltage feedback loop. The CS pin (current detection feedback pin) of the switching chip U1 is connected to the sampling voltage of the sampling resistor R0. A comparator outputs a low level to control the turn-off of the N-type MOSFET Q1 when the sampled voltage exceeds a first preset voltage threshold.

[0041] In one specific embodiment, the switching chip U1 is used to reduce the duty cycle of the PWM signal when the second voltage value is greater than the second preset voltage threshold, and to increase the duty cycle of the PWM signal when the second voltage value is less than the second preset voltage threshold.

[0042] In one specific embodiment, the second preset voltage threshold is set to 2.5V.

[0043] Specifically, the switching chip U1 includes an error amplifier. The inverting input of the error amplifier is connected to the FB pin of the switching chip U1, and the non-inverting input is connected to a second preset voltage threshold (2.5V ± 1%). The FB pin uses negative logic feedback. That is, when the voltage at the FB pin increases to above 2.5V, the switching chip U1 controls the N-type MOSFET Q1 to reduce the duty cycle of the PWM signal, thereby reducing the voltage of the DC signal output by the boost module 10. Conversely, when the voltage at the FB pin decreases to below 2.5V, the switching chip U1 controls the N-type MOSFET Q1 to increase the duty cycle of the PWM signal, thereby increasing the voltage of the DC signal output by the boost module 10.

[0044] In this embodiment, the switch chip U1 is used to acquire the sampling voltage of the sampling resistor R0, and to use the comparator of the switch chip U1 to determine whether the sampling voltage is greater than a first preset voltage threshold. When the sampling voltage is greater than the first preset voltage threshold, a low-level signal is output to turn off the N-type MOS transistor Q1.

[0045] In one specific embodiment, the first preset voltage threshold is set to 1V. The resistance value of the sampling resistor R0 is set according to the magnitude of the first preset voltage threshold.

[0046] Specifically, the switching chip U1 includes a comparator. The non-inverting input of the comparator is connected to the sampling voltage of the sampling resistor R0, and the inverting input of the comparator is connected to a first preset voltage threshold (1V). The comparator compares the sampled voltage with the first preset voltage threshold. When the sampled voltage is greater than the first preset voltage threshold, the switching chip U1 outputs a low-level signal to turn off the N-type MOSFET Q1.

[0047] In a specific example, the switch chip U1 is a UCC28C43 model switch chip, and the N-type MOSFET Q1 is a BSC093N15 model N-type MOSFET.

[0048] In one specific embodiment, such as Figure 2 As shown, the feedback circuit 21 includes a first resistor R1, a first operational amplifier A1, and a second resistor R2. The first end of the first resistor R1 is connected to the input terminal of the feedback circuit 21, the second end of the first resistor R1 is connected to the negative input terminal of the first operational amplifier A1, the positive input terminal of the first operational amplifier A1 is grounded, the output terminal of the first operational amplifier A1 is connected to the output terminal of the feedback circuit 21, and the output terminal of the first operational amplifier A1 is also connected to the negative input terminal of the first operational amplifier A1 through the second resistor R2.

[0049] Specifically, the feedback circuit 21 uses the first resistor R1, the first operational amplifier A1, and the second resistor R2 to convert the DC signal output by the boost module 10 to positive and proportionally reduce it.

[0050] In a specific example, the first op-amp A1 is a high-speed op-amp of model AD8642.

[0051] In one specific embodiment, the boost module 10 includes a transformer 11 and a boost circuit 12. The first input terminal of the transformer 11 is connected to the first input terminal of the boost circuit 12, the second input terminal of the transformer 11 is connected to the second input terminal of the boost circuit 12, the first output terminal of the transformer 11 is connected to the first input terminal of the boost circuit 12, the second output terminal of the transformer 11 is grounded and connected to the second input terminal of the boost circuit 12, and the output terminal of the boost circuit 12 is connected to the output terminal of the boost module 10.

[0052] Specifically, the boost module 10 uses a transformer combined with the boost circuit 12 to double the input DC signal, which can greatly reduce the size of the transformer, that is, use an ultra-small transformer, thereby further reducing the size of the negative high voltage power supply 100.

[0053] In one specific embodiment, transformer 11 is an ultra-small size transformer. For example, an EPC10-24360-T1 model transformer can be used.

[0054] In one specific embodiment, such as Figure 3 As shown, the boost circuit 12 may include multiple sets of capacitors and diodes.

[0055] Specifically, the boost circuit 12 employs a bootstrap principle, using high-voltage-resistant diodes and capacitors to multiply the AC voltage output from the secondary side of the transformer. It should be noted that the number of capacitor and diode groups can be set according to the desired amplification factor. Through calculation and multiple voltage multiplications, the number of capacitor and diode groups is set to achieve the target negative voltage value. This invention does not limit the number of capacitor and diode groups.

[0056] The negative high-voltage power supply of this utility model embodiment is suitable for high-temperature environments underground, where the high temperature can reach 175°C.

[0057] As a specific example, such as Figure 4 As shown, the boost circuit 12 may include a first capacitor C1, a first diode D1, a second capacitor C2, a second diode D2, a third capacitor C3, a third diode D3, a fourth capacitor C4, a fourth diode D4, a fifth capacitor C5, a fifth diode D5, a sixth capacitor C6, and a sixth diode D6. The first terminal of the first capacitor C1 is connected to the first input terminal of the boost circuit 12, and the second terminal of the first capacitor C1 is connected to the anode of the first diode D1. The cathode of the first diode D1 is connected to the second input terminal of the boost circuit 12. The cathode of the first diode D1 is connected to the anode of the second diode D2 through the second capacitor C2, and the cathode of the second diode D2 is connected to the anode of the second diode D2 through the third capacitor C3. The positive terminal of the third diode D3 is connected to the positive terminal of the second diode D2. The negative terminal of the third diode D3 is connected to the positive terminal of the fourth diode D4 through the fourth capacitor C4. The negative terminal of the fourth diode D4 is connected to the positive terminal of the third diode D3. The negative terminal of the fourth diode D4 is connected to the positive terminal of the fifth diode D5 through the fifth capacitor C5. The negative terminal of the fifth diode D5 is connected to the positive terminal of the fourth diode D4. The negative terminal of the fifth diode D5 is connected to the positive terminal of the sixth diode D6 through the sixth capacitor C6. The negative terminal of the sixth diode D6 is connected to the positive terminal of the fifth diode D5. The positive terminal of the sixth diode D6 is connected to the output terminal of the boost circuit 12.

[0058] In this embodiment, the boost circuit 12 uses six sets of capacitors and diodes to double the AC voltage output from the secondary side of the transformer. With the first voltage value being a 10V DC signal, the negative high-voltage power supply 100 in this embodiment can achieve a power supply voltage regulation range of -1500V to -2400V.

[0059] It should be noted that the embodiments of this utility model do not limit the models and parameters of the above-mentioned devices, such as resistors, capacitors, operational amplifiers, and switching chips, and can be set according to actual needs.

[0060] This embodiment of the invention, a negative high-voltage power supply 100, uses a switching chip U1 to drive the output of a PWM signal, combined with an ultra-small transformer, to form the primary circuit of the power supply. It employs dual voltage and current feedback to control the output of the PWM signal, rapidly adjusting the duty cycle of the PWM signal at a fixed frequency to regulate the output voltage of the boost module 10.

[0061] The current feedback uses a high-precision sampling resistor R0 on the primary side of the power supply to monitor and provide feedback on the primary current, thereby controlling the duty cycle and providing current protection. For voltage feedback, since the output voltage of the boost module 10 is negative, this invention employs a feedback circuit 21 composed of a first operational amplifier A1 to convert negative voltage to positive voltage and scale it down proportionally. The output voltage of the feedback circuit 21 is designed to be the feedback point voltage of the switching chip U1. Fluctuations in the output voltage of the boost module 10 are fed back to the switching chip U1 through this feedback circuit 21. Then, the error amplification and comparison circuit inside the switching chip U1 adjusts the duty cycle to achieve voltage stabilization.

[0062] It should be noted that when the PWM signal is high, the N-type MOSFET Q1 is turned on. When the PWM signal is low, the N-type MOSFET Q1 is turned off. Specifically, when the N-type MOSFET Q1 is on, the rectifier diodes in the secondary boost section of the transformer are reverse-biased and cut off, and the output capacitor supplies power to the load. Transformer 11 acts as a pure inductor, and the current flowing through the primary side of the transformer rises linearly to reach its peak value Ip. When the N-type MOSFET Q1 is turned off, all winding voltages reverse, and this flyback voltage causes the diodes in the output boost section to turn on, while the energy stored in the primary side of transformer 11, 1 / 2LIp, is released. 2 It is transmitted to the secondary side to provide load current and simultaneously charge the output capacitor.

[0063] The negative high voltage power supply of this utility model adopts voltage and current dual feedback to control the output of the PWM signal. The duty cycle of the PWM signal is quickly adjusted at a fixed frequency to regulate the output voltage of the boost module, so that the negative high voltage power supply provides a stable negative high voltage DC signal to the load. At the same time, it can also disconnect the negative high voltage power supply 100 in time when a short circuit occurs in the load.

[0064] This utility model provides a downhole device.

[0065] Figure 5 This is a schematic diagram of a downhole device according to an embodiment of the present invention. Figure 5 As shown, the downhole equipment 1000 includes the negative high-voltage power supply 100 as described above.

[0066] Specifically, the first input terminal of the boost module in the negative high voltage power supply 100 is connected to the input terminal of the power supply, and the output terminal of the boost module in the negative high voltage power supply 100 is connected to the load. The negative high voltage power supply 100 provides a stable DC signal with a target negative voltage value to the load in the downhole equipment 1000, and disconnects the power supply of the negative high voltage power supply 100 in time when a short circuit occurs in the load to protect the downhole equipment 1000.

[0067] The downhole equipment of this utility model embodiment can use the above-mentioned negative high voltage power supply to provide a stable negative high voltage DC signal to the load.

[0068] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0069] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0070] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0071] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0072] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0073] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A negative high voltage power supply characterized by, The power supply comprises: a voltage boosting module, a first input end of the voltage boosting module being connected with an input end of a power supply, so as to boost a direct current signal of a first voltage value input by the power supply; an N-type MOS tube, a drain of the N-type MOS tube being connected with a second input end of the voltage boosting module; a sampling resistor, a first end of the sampling resistor being connected with a source of the N-type MOS tube, and a second end of the sampling resistor being grounded; a control module, a first input end of the control module being connected with an output end of the voltage boosting module, a second input end of the control module being connected with the first end of the sampling resistor, and an output end of the control module being connected with a gate of the N-type MOS tube, so as to collect a direct current signal output by the output end of the voltage boosting module, adjust a duty cycle of a PWM signal input to the N-type MOS tube according to a voltage of the direct current signal output by the voltage boosting module, make the voltage boosting module output a direct current signal of a target negative voltage value, and collect a sampling voltage of the sampling resistor, and control to turn off the N-type MOS tube when the sampling voltage is greater than a first preset voltage threshold.

2. The negative high voltage power supply of claim 1, wherein, The control module comprises: a feedback circuit, an input end of the feedback circuit being connected to the first input end of the control module, so as to collect the direct current signal output by the output end of the voltage boosting module, convert the direct current signal output by the voltage boosting module into a direct current signal of a positive voltage value, and reduce the direct current signal of the positive voltage value into a direct current signal of a second voltage value; a switch chip, an FB end of the switch chip being connected with an output end of the feedback circuit, a CS end of the switch chip being connected to the second input end of the control module, and an output end of the switch chip being connected to the output end of the control module, so as to adjust the duty cycle of the PWM signal input to the N-type MOS tube according to the direct current signal of the second voltage value, and collect the sampling voltage of the sampling resistor, and control to turn off the N-type MOS tube when the sampling voltage is greater than the first preset voltage threshold.

3. The negative high voltage power supply of claim 2, wherein, The switch chip is used to reduce the duty cycle of the PWM signal when the second voltage value is greater than a second preset voltage threshold, and increase the duty cycle of the PWM signal when the second voltage value is less than the second preset voltage threshold.

4. The negative high voltage power supply of claim 2, wherein, The switch chip is used to collect the sampling voltage of the sampling resistor, judge whether the sampling voltage is greater than the first preset voltage threshold by using a comparator of the switch chip, and output a low-level signal to turn off the N-type MOS tube when the sampling voltage is greater than the first preset voltage threshold.

5. The negative high voltage power supply of claim 2, wherein, The feedback circuit comprises a first resistor, a first operational amplifier and a second resistor, a first end of the first resistor being connected to an input end of the feedback circuit, a second end of the first resistor being connected with a negative phase end of the first operational amplifier, a positive phase end of the first operational amplifier being grounded, an output end of the first operational amplifier being connected to an output end of the feedback circuit, and the output end of the first operational amplifier further being connected with the negative phase end of the first operational amplifier through the second resistor.

6. The negative high voltage power supply of claim 1, wherein, The voltage boosting module comprises a transformer and a voltage boosting circuit, a first input end of the transformer is connected to, a second input end of the transformer is connected to, a first output end of the transformer is connected with a first input end of the voltage boosting circuit, a second output end of the transformer is grounded and connected with a second input end of the voltage boosting circuit, and an output end of the voltage boosting circuit is connected to an output end of the voltage boosting module.

7. A negative high voltage power supply as claimed in claim 6, characterized in that The voltage boosting circuit comprises multiple groups of capacitors and diodes.

8. The negative high voltage power supply of claim 7, wherein, The voltage boosting circuit comprises a first capacitor, a first diode, a second capacitor, a second diode, a third capacitor, a third diode, a fourth capacitor, a fourth diode, a fifth capacitor, a fifth diode, a sixth capacitor and a sixth diode, a first end of the first capacitor is connected to a first input end of the voltage boosting circuit, a second end of the first capacitor is connected with a positive electrode of the first diode, a negative electrode of the first diode is connected to a second input end of the voltage boosting circuit, the negative electrode of the first diode is connected with a positive electrode of the second diode through the second capacitor, a negative electrode of the second diode is connected with a positive electrode of the third diode through the third capacitor, a negative electrode of the third diode is connected with a positive electrode of the second diode, a negative electrode of the third diode is connected with a positive electrode of the fourth diode through the fourth capacitor, a negative electrode of the fourth diode is connected with a positive electrode of the third diode, a negative electrode of the fourth diode is connected with a positive electrode of the fifth diode through the fifth capacitor, a negative electrode of the fifth diode is connected with a positive electrode of the fourth diode, a negative electrode of the fifth diode is connected with a positive electrode of the sixth diode through the sixth capacitor, a negative electrode of the sixth diode is connected with a positive electrode of the fifth diode, and a positive electrode of the sixth diode is connected to an output end of the voltage boosting circuit.

9. A downhole apparatus, characterized by The negative high-voltage power supply comprises the voltage boosting module as claimed in any one of claims 1-8.

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