Motor speed measurement circuit and a while-drilling system

Abstract

The utility model discloses a motor rotation speed measurement circuit and drilling system relates to drilling technical field. Circuit includes: rectifying unit, hysteresis comparison unit, inverter and treater, wherein, the input of rectifying unit is connected with any phase of motor, and the output of rectifying unit is connected with the input of hysteresis comparison unit, and rectifying unit is configured to remove the negative polarity part in input signal, the output of hysteresis comparison unit is connected with the input of inverter, and the output of inverter is connected with treater, and treater is configured as the rotation speed of motor is obtained according to the output signal of inverter. The circuit can realize accurate measurement of motor rotation speed, help subsequent accurate control of motor power based on rotation speed, avoid the damage of motor caused by excessive power.

Description

Technical Field

[0001] This utility model relates to the field of drilling technology, and in particular to a motor speed measurement circuit and a drilling system. Background Technology

[0002] In Measurement While Drilling (MWD) and Logging While Drilling (LWD) systems, the turbine generator is the core device that provides power to downhole electronic instruments and pulsers. It directly converts the kinetic energy of the drilling fluid (mud) flow into electrical energy, eliminating the need for batteries and enabling long-term continuous power supply to downhole equipment.

[0003] When drilling fluid flows through the turbine generator, it impacts the rotor blades, causing them to rotate at high speed and converting the fluid's kinetic energy into mechanical energy. The rotating rotor drives the permanent magnet to rotate, and the rotating magnetic field cuts the stator coils to generate an induced current, converting mechanical energy into electrical energy to power downhole instruments. Therefore, ensuring the turbine generator operates stably for extended periods and preventing damage is crucial. Utility Model Content

[0004] The purpose of this invention is to propose a motor speed measurement circuit and a drilling system to achieve accurate measurement of motor speed, which helps to accurately control motor power based on speed and avoid damage to the motor caused by excessive power.

[0005] In a first aspect, this utility model proposes a motor speed measurement circuit, comprising: a rectifier unit, a hysteresis comparator unit, an inverter, and a processor; wherein, the input terminal of the rectifier unit is connected to any phase of the motor, the output terminal of the rectifier unit is connected to the input terminal of the hysteresis comparator unit, and the rectifier unit is configured to remove the negative polarity portion of the input signal; the output terminal of the hysteresis comparator unit is connected to the input terminal of the inverter, and the output terminal of the inverter is connected to the processor; the processor is configured to obtain the motor speed based on the output signal of the inverter.

[0006] In some examples, the rectifier unit includes a diode, with the anode of the diode serving as the input terminal of the rectifier unit and the cathode of the diode serving as the output terminal of the rectifier unit.

[0007] In some examples, the circuit further includes a voltage divider unit, which includes a first voltage divider resistor and a second voltage divider resistor. One end of the first voltage divider resistor is connected to the output terminal of the rectifier unit, and the other end of the first voltage divider resistor is connected to the input terminal of the hysteresis comparator unit and one end of the second voltage divider resistor, respectively. The other end of the second voltage divider resistor is grounded.

[0008] In some examples, the circuit further includes a Zener diode, the anode of which is connected to the other end of the second voltage divider resistor, and the cathode of which is connected to one end of the second voltage divider resistor.

[0009] In some examples, the circuit also includes a filter capacitor connected in parallel with the second voltage divider resistor.

[0010] In some examples, the hysteresis comparator includes a comparator, a reference resistor, a feedback resistor, and a grounding resistor; Wherein, one end of the reference resistor is adapted to be connected to a preset power supply, and the other end of the reference resistor is connected to one end of the grounding resistor, one end of the feedback resistor, and the non-inverting input terminal of the comparator. The other end of the grounding resistor is grounded, and the other end of the feedback resistor is connected to the output terminal of the comparator. The inverting input terminal of the comparator serves as the input terminal of the hysteresis comparison unit, and the output terminal of the comparator serves as the output terminal of the hysteresis comparison unit.

[0011] In some examples, the circuit further includes a first decoupling capacitor and a second decoupling capacitor; wherein one end of the first decoupling capacitor is connected to the power supply terminal of the comparator and the other end of the first decoupling capacitor is grounded, one end of the second decoupling capacitor is connected to the power supply terminal of the inverter and the other end of the second decoupling capacitor is grounded.

[0012] In some examples, the circuit further includes pull-up resistors and pull-down resistors, one end of the pull-up resistor being connected to the output of the comparator and the other end of the pull-up resistor being adapted to be connected to a preset power supply, one end of the pull-down resistor being connected to the output of the inverter and the other end of the pull-down resistor being grounded.

[0013] In some examples, the circuit also includes a current-limiting resistor connected between the output of the inverter (U2) and the processor.

[0014] Secondly, this utility model proposes a drilling system, including: a motor, and the motor speed measurement circuit described in the first aspect above, wherein the motor is a turbine generator.

[0015] The motor speed measurement circuit and drilling system of this utility model embodiment remove the negative polarity portion from the motor input signal through a rectifier unit, compare the rectified input signal through a hysteresis comparator unit, and invert the comparison result through an inverter before outputting it to a processor. The processor then obtains the motor speed based on the output signal of the inverter. This enables accurate measurement of the motor speed, facilitating accurate subsequent control of motor power based on the speed and preventing damage to the motor due to excessive power. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the motor speed measuring circuit according to an embodiment of the present invention; Figure 2 This is a topology diagram of the motor speed measurement circuit of the first example of this utility model; Figure 3 This is a topology diagram of the motor speed measurement circuit of the second example of this utility model; Figure 4 This is a topology diagram of the motor speed measurement circuit of the third example of this utility model; Figure 5 This is the topology diagram of the motor speed measurement circuit of the fourth example of this utility model; Figure 6 This is the topology diagram of the motor speed measurement circuit of the fifth example of this utility model; Figure 7 This is the topology diagram of the motor speed measurement circuit of the sixth example of this utility model; Figure 8 This is a schematic diagram of the structure of the drilling system according to an embodiment of the present invention. Detailed Implementation

[0017] 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.

[0018] The following description, with reference to the accompanying drawings, describes an embodiment of the present invention: a motor speed measurement circuit and a drilling system.

[0019] Figure 1 This is a schematic diagram of the motor speed measurement circuit according to an embodiment of the present invention.

[0020] like Figure 1 As shown, the motor speed measurement circuit 10 includes: a rectifier unit 11, a hysteresis comparison unit 12, an inverter U2, and a processor 13.

[0021] The input terminal of the rectifier unit 11 is connected to any phase of the motor M (such as a turbine generator in a drilling system, typically located near the drill bit or measuring sub to directly utilize the kinetic energy of the drilling fluid flow). The motor M has three phases: U, V, and W, with the same frequency and a 120° phase difference. The output terminal of the rectifier unit 11 is connected to the input terminal of the hysteresis comparator unit 12. The rectifier unit 11 is configured to remove the negative polarity portion of the input signal. The output terminal of the hysteresis comparator unit 12 is connected to the input terminal of the inverter U2. The output terminal of the inverter U2 is connected to the processor 13. The processor 13 is configured to obtain the rotational speed of the motor M based on the output signal of the inverter U2.

[0022] Taking the motor M as an example of a turbine generator, the output power of the turbine generator is positively correlated with the frequency of the output three-phase electricity. Based on this characteristic, a motor speed measurement circuit 10 is designed inside the drilling system. Any phase of the turbine generator (such as phase W) is connected to the input terminal of the rectifier unit 11 to remove the negative polarity part of the phase's electrical signal. Then, the analog signal (which may contain noise) output by the rectifier unit 11 is converted into a clean digital pulse by the hysteresis comparator unit 12. Its hysteresis function can prevent jitter near the threshold. Then, the digital pulse output by the hysteresis comparator unit 12 is "beautified" (such as shaped and accelerated edges) by the inverter, and a standard, clean, powerful, and correctly polarized square wave signal is output to the processor 13. Processor 13 acquires the rising edges of the high and low level signals output by inverter U2 and records the number of high and low levels per second, enabling precise frequency / period measurement (i.e., real-time monitoring of the three-phase frequency output by the turbine generator). Then, based on the frequency, it accurately calculates the turbine generator's rotational speed using the formula f=(P×n) / 60, where f is the frequency, n is the rotational speed, and P is the number of pole pairs of the turbine generator. After obtaining the rotational speed, it can be uploaded to the ground system, allowing for dynamic adjustment of the turbine generator's output power to prevent damage caused by excessive power.

[0023] For example, the inverter U2 can be an NC7S04M5X, which features small size, low power consumption, and high temperature resistance. The processor 13 can be an MCU (Microcontroller Unit), which features high integration, low cost, flexibility, and reliability.

[0024] In some examples of this utility model, such as Figure 2 As shown, the hysteresis comparator unit 12 includes a comparator U1, a reference resistor R1, a feedback resistor R2, and a grounding resistor R3.

[0025] One end of the reference resistor R1 is suitable for connecting to a preset power supply (such as a +5V power supply). The other end of the reference resistor R1 is connected to one end of the grounding resistor R3, one end of the feedback resistor R2, and the non-inverting input of the comparator U1. The other end of the grounding resistor R3 is grounded. The other end of the feedback resistor R2 is connected to the output of the comparator U1. The inverting input of the comparator U1 serves as the input of the hysteresis comparator unit 12, and the output of the comparator U1 serves as the output of the hysteresis comparator unit 12.

[0026] In this example, the reference resistor R1, feedback resistor R2, ground resistor R3, and comparator U1 can be selected as needed. For example, the resistance of R1 can be 100KΩ, the resistance of R2 300KΩ, the resistance of R3 5.1KΩ, and the model of comparator U1 is LM193DR. See also Figure 2 Pin 3 of comparator U1 is the comparison threshold terminal. Let the voltage at pin 2 be V. in- The voltage at pin 3 is V. in+ The voltage at pin 1 is U. OH High level and U OL Low level, then When V in- < V in hour, =0.238V + 0.079V = 0.317V; When V in- >V in+ hour, =0.238V; This creates a hysteresis range of 0.079V, which can prevent the comparator U1 output from oscillating.

[0027] The signal at pin 1 of comparator U1 is inverted by inverter U2, becoming a high or low level signal with the same frequency as the input phase M of motor (such as phase W). It is then input to the IO pin of processor 13 and converted into speed.

[0028] For example, such as Figure 3 As shown, the motor speed measurement circuit 10 also includes a first decoupling capacitor C1 and a second decoupling capacitor C2. One end of the first decoupling capacitor C1 is connected to the power supply terminal of the comparator U1, and the other end of the first decoupling capacitor C1 is grounded. One end of the second decoupling capacitor C2 is connected to the power supply terminal of the inverter U2, and the other end of the second decoupling capacitor C2 is grounded.

[0029] The first decoupling capacitor C1 and the second decoupling capacitor C2 can be selected as needed, such as both being 0.1μF / 50V. By setting the decoupling capacitors, local and instantaneous current can be provided to the comparator U1 and the inverter U2 respectively, maintaining the stability of the power supply voltage and filtering out high-frequency noise generated during signal transmission.

[0030] For example, such as Figure 4 As shown, the motor speed measurement circuit 10 also includes a pull-up resistor R4 and a pull-down resistor R8. One end of the pull-up resistor R4 is connected to the output terminal of the comparator U1, and the other end of the pull-up resistor R4 is adapted to be connected to a preset power supply. One end of the pull-down resistor R8 is connected to the output terminal of the inverter U2, and the other end of the pull-down resistor R8 is grounded.

[0031] Both pull-up resistors R4 and R8 can be selected according to requirements, such as both being 10KΩ. The pull-up resistor R4 ensures that the comparator U1 outputs a clear, stable high level that can be correctly recognized by the subsequent inverter U2. The pull-down resistor R8 provides a definite low-level logic state for the inverter U2 when its output is in a high-impedance state, preventing the output from floating and thus enhancing the system's anti-interference capability and reliability.

[0032] As one implementation method, such as Figure 5 As shown, the rectifier unit 11 includes a diode D1, with the anode of the diode D1 serving as the input terminal of the rectifier unit 11 and the cathode of the diode D1 serving as the output terminal of the rectifier unit 11.

[0033] Taking phase W as an example, it is a sinusoidal signal with positive and negative polarities. After being rectified by diode D1, the negative polarity part of the signal can be removed.

[0034] In some examples of this utility model, such as Figure 6 As shown, the motor speed measurement circuit 10 also includes a voltage divider unit 14. The voltage divider unit 14 includes a first voltage divider resistor R5 and a second voltage divider resistor R7. One end of the first voltage divider resistor R5 is connected to the output terminal of the rectifier unit 11. The other end of the first voltage divider resistor R5 is connected to the input terminal of the hysteresis comparator unit 12 and one end of the second voltage divider resistor R7. The other end of the second voltage divider resistor R7 is grounded.

[0035] The voltage divider resistors R5 and R7 can be selected as needed, such as R5 being 200KΩ and R7 being 10K ohms. After rectification by diode D1, the remaining positive voltage is divided by R5 and R7, which can reduce it by a preset factor (such as 21 times) and input to pin 2 of comparator U1.

[0036] For example, such as Figure 7 As shown, the motor speed measurement circuit 10 also includes a Zener diode D2, a filter capacitor C3, and a current-limiting resistor R6. The anode of the Zener diode D2 is connected to the other end of the second voltage divider resistor R7, and the cathode of the Zener diode D2 is connected to one end of the second voltage divider resistor R7. The filter capacitor C3 is connected in parallel with the second voltage divider resistor R7. The current-limiting resistor R6 is connected between the output terminal of the inverter U2 and the processor 13.

[0037] The Zener diode D2, filter capacitor C3, and current-limiting resistor R6 can all be selected according to requirements. For example, the Zener diode D2 has a Zener voltage of 4.3V, which can be used to protect the input pins of comparator U1. The filter capacitor C3 is 100pF / 50V, which can form an RC filter circuit with resistor R5, with a cutoff frequency of 7.958KHz. The ideal speed range of the turbine generator is 2500-3200 rpm, corresponding to a three-phase power frequency of 166.67-213.33Hz. The cutoff frequency of the RC filter circuit is much higher than the three-phase power frequency, meeting the design requirements. The current-limiting resistor R6 can be 10Ω, which can protect the I / O pins of processor 13.

[0038] In summary, the motor speed measurement circuit 10 of this utility model embodiment can accurately measure the motor speed with a speed error of less than ±5 rpm; moreover, it can be used in high-temperature scenarios, specifically, it can work normally for a long time at 175℃, which can meet the needs of underground use.

[0039] Based on the motor speed measurement circuit 10 of the above embodiment, this utility model proposes a drilling system.

[0040] In this embodiment, such as Figure 8 As shown, the drilling system 100 includes: a motor M, and a motor speed measurement circuit 10 as described in the above embodiment, wherein the motor M is a turbine generator.

[0041] In the description of this specification, the 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.

[0042] 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.

[0043] In this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed," 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.

[0044] 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.

[0045] 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 motor speed measuring circuit (10), characterized in that, include: The rectifier unit (11), the hysteresis comparator unit (12), the inverter (U2), and the processor (13) are included. The input terminal of the rectifier unit (11) is connected to any phase of the motor (M), and the output terminal of the rectifier unit (11) is connected to the input terminal of the hysteresis comparator unit (12). The rectifier unit (11) is configured to remove the negative polarity portion of the input signal. The output terminal of the hysteresis comparator unit (12) is connected to the input terminal of the inverter (U2), and the output terminal of the inverter (U2) is connected to the processor (13). The processor (13) is configured to obtain the rotational speed of the motor (M) based on the output signal of the inverter (U2).

2. The motor speed measuring circuit (10) according to claim 1, characterized in that, The rectifier unit (11) includes a diode (D1), the anode of the diode (D1) serves as the input terminal of the rectifier unit (11), and the cathode of the diode (D1) serves as the output terminal of the rectifier unit (11).

3. The motor speed measuring circuit (10) according to claim 1, characterized in that, The circuit (10) further includes a voltage divider unit, which includes a first voltage divider resistor (R5) and a second voltage divider resistor (R7). One end of the first voltage divider resistor (R5) is connected to the output terminal of the rectifier unit (11), and the other end of the first voltage divider resistor (R5) is connected to the input terminal of the hysteresis comparator unit (12) and one end of the second voltage divider resistor (R7), respectively. The other end of the second voltage divider resistor (R7) is grounded.

4. The motor speed measuring circuit (10) according to claim 3, characterized in that, The circuit (10) further includes a Zener diode (D2), the anode of which is connected to the other end of the second voltage divider resistor (R7), and the cathode of which is connected to one end of the second voltage divider resistor (R7).

5. The motor speed measuring circuit (10) according to claim 3, characterized in that, The circuit (10) further includes a filter capacitor (C3), which is connected in parallel with the second voltage divider resistor (R7).

6. The motor speed measuring circuit (10) according to claim 1, characterized in that, The hysteresis comparison unit (12) includes a comparator (U1), a reference resistor (R1), a feedback resistor (R2), and a grounding resistor (R3). Wherein, one end of the reference resistor (R1) is adapted to be connected to a preset power supply, and the other end of the reference resistor (R1) is connected to one end of the grounding resistor (R3), one end of the feedback resistor (R2), and the non-inverting input terminal of the comparator (U1), respectively. The other end of the grounding resistor (R3) is grounded, and the other end of the feedback resistor (R2) is connected to the output terminal of the comparator (U1). The inverting input terminal of the comparator (U1) serves as the input terminal of the hysteresis comparator unit (12), and the output terminal of the comparator (U1) serves as the output terminal of the hysteresis comparator unit (12).

7. The motor speed measuring circuit (10) according to claim 6, characterized in that, The circuit (10) also includes a first decoupling capacitor (C1) and a second decoupling capacitor (C2); In this circuit, one end of the first decoupling capacitor (C1) is connected to the power supply terminal of the comparator (U1), and the other end of the first decoupling capacitor (C1) is grounded. One end of the second decoupling capacitor (C2) is connected to the power supply terminal of the inverter (U2), and the other end of the second decoupling capacitor (C2) is grounded.

8. The motor speed measuring circuit (10) according to claim 6, characterized in that, The circuit (10) further includes a pull-up resistor (R4) and a pull-down resistor (R8). One end of the pull-up resistor (R4) is connected to the output of the comparator (U1), and the other end of the pull-up resistor (R4) is adapted to be connected to a preset power supply. One end of the pull-down resistor (R8) is connected to the output of the inverter (U2), and the other end of the pull-down resistor (R8) is grounded.

9. The motor speed measuring circuit (10) according to any one of claims 1-8, characterized in that, The circuit (10) also includes a current-limiting resistor (R6) connected between the output of the inverter (U2) and the processor (13).

10. A drilling system, characterized in that, include: The motor (M) and the motor speed measuring circuit (10) as described in any one of claims 1-9, wherein the motor (M) is a turbine generator.

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