阅读说明：本技术 一种钻井无线随钻仪的宽范围ac-dc电源转换系统及方法 (Wide-range AC-DC power supply conversion system and method of drilling wireless while-drilling instrument ) 是由 卢祥明 余民 于 2021-01-07 设计创作，主要内容包括：本发明公开一种钻井无线随钻仪的宽范围AC-DC电源转换系统及方法,包括：三相整流电路与滤波均压电路连接,用于将三相交流电压经整流与滤波后输出直流电压；滤波均压电路与双侧双BUCK PWM变换电路连接,双侧双BUCK PWM变换电路与冲激稳压变压器连接,双侧双BUCK PWM变换电路包括第一MOS管、第二MOS管、驱动电路和PWM变换电路；在滤波均压电路的正极和中点电压之间,中点电压和负极之间分别接入第一MOS管和第二MOS管,通过驱动电路和PWM变换电路控制双MOS管动作,在双MOS管未同步动作时,冲激稳压变压器双边线圈产生电压相同且极性相反的感应电压,以使双MOS管保持半压,以对直流电压进行PWM调制后输出目标电压。对井下三相发电机输出的AC50-500V电压实现AC-DC转换,并稳定工作。(The invention discloses a wide-range AC-DC power supply conversion system and method of a drilling wireless while-drilling instrument, which comprises the following steps: the three-phase rectifying circuit is connected with the filtering and voltage-equalizing circuit and is used for rectifying and filtering the three-phase alternating-current voltage and outputting direct-current voltage; the filter voltage-sharing circuit is connected with the double-side double-BUCK PWM conversion circuit, the double-side double-BUCK PWM conversion circuit is connected with the impulse voltage-stabilizing transformer, and the double-side double-BUCK PWM conversion circuit comprises a first MOS (metal oxide semiconductor) tube, a second MOS tube, a driving circuit and a PWM conversion circuit; a first MOS tube and a second MOS tube are respectively connected between the positive pole and the middle point voltage of the filter voltage-sharing circuit and between the middle point voltage and the negative pole, the action of the double MOS tubes is controlled by the driving circuit and the PWM conversion circuit, and when the double MOS tubes do not synchronously act, the double-side coils of the impulse voltage-stabilizing transformer generate induced voltages with the same voltage and opposite polarities so as to keep the double MOS tubes at half voltage and output target voltage after PWM modulation is carried out on the direct current voltage. The AC50-500V voltage output by the underground three-phase generator is converted into AC-DC voltage and works stably.)

1. A wide-range AC-DC power conversion system of a drilling wireless while drilling instrument, comprising: the device comprises a three-phase rectification circuit, a filtering voltage-sharing circuit, a double-side BUCK PWM conversion circuit and an impulse voltage-stabilizing transformer;

the three-phase rectifying circuit is connected with the filtering and voltage-equalizing circuit and is used for rectifying and filtering the three-phase alternating-current voltage and then outputting direct-current voltage;

the filter voltage-sharing circuit is connected with the double-side double-BUCK PWM conversion circuit, the double-side double-BUCK PWM conversion circuit is connected with the impulse voltage-stabilizing transformer, and the double-side double-BUCK PWM conversion circuit comprises a first MOS (metal oxide semiconductor) tube, a second MOS tube, a driving circuit and a PWM conversion circuit;

a first MOS tube and a second MOS tube are respectively connected between the positive pole and the middle point voltage of the filter voltage-sharing circuit and between the middle point voltage and the negative pole, the action of the double MOS tubes is controlled by the driving circuit and the PWM conversion circuit, and when the double MOS tubes do not synchronously act, the double-side coils of the impulse voltage-stabilizing transformer generate induced voltages with the same voltage and opposite polarities so as to keep the double MOS tubes at half voltage and output target voltage after PWM modulation is carried out on the direct current voltage.

2. The system of claim 1, wherein the three-phase rectification circuit comprises a three-phase rectifier diode group to rectify a three-phase AC voltage of 50-500V into a DC pulsating voltage.

3. The system of claim 1, wherein the filter voltage-sharing circuit comprises two filter capacitors connected in series for filtering the rectified DC pulsating voltage into a DC voltage.

4. The system of claim 3, wherein the midpoint voltage is at the midpoint of the two series connected filter capacitors.

5. The wide-range AC-DC power conversion system of the drilling wireless while drilling instrument as claimed in claim 1, wherein the driving circuit and the PWM conversion circuit control the first MOS transistor and the second MOS transistor to synchronously perform pulse width modulation on-off switching according to the input voltage and the load change.

6. The wide-range AC-DC power conversion system of the drilling wireless while drilling instrument as claimed in claim 1, wherein the first MOS transistor and the second MOS transistor are both N-channel transistors.

7. The wide-range AC-DC power conversion system of the drilling wireless while drilling instrument as claimed in claim 1, wherein a first diode and a second diode are connected between the first MOS tube and the second MOS tube.

8. The wide-range AC-DC power conversion system of the drilling wireless while-drilling instrument as claimed in claim 1, wherein the impulse voltage-stabilizing transformer has two groups of coils with the same number of turns and the same wire diameter and the same ends are opposite.

9. The system of claim 1, further comprising a sampling circuit and a high frequency filter circuit connected to each other, wherein the sampling circuit determines a target voltage value, and the high frequency filter circuit filters the PWM modulated DC voltage to output the target voltage.

10. A wide-range AC-DC power conversion method of a drilling wireless while drilling instrument is characterized by comprising the following steps:

rectifying and filtering the obtained three-phase alternating voltage and then outputting direct-current voltage;

the double MOS tubes are controlled to act through a driving circuit and a PWM conversion circuit so as to output target voltage after PWM modulation is carried out on direct-current voltage;

if the double MOS tubes do not act synchronously, the double-side coil of the impulse voltage-stabilizing transformer generates induced voltages with the same voltage and opposite polarities so as to keep the double MOS tubes in a half-voltage state.

Technical Field

The invention relates to the technical field of wireless while-drilling systems for oil field drilling, in particular to a wide-range AC-DC power supply conversion system and method for a wireless while-drilling instrument for drilling.

Background

The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.

In the oil field drilling process, a wireless drilling system is provided with a spectrum measurement system and a rotary steering system, the two systems are powered by a high-power supply, and the power supply can be realized only by utilizing a downhole generator. However, the driving force of the downhole generator comes from the mud flow circulating during drilling, the flow rate and the pressure of the mud flow depend on the working state of the mud pump, the output voltage of the downhole generator greatly fluctuates, and the actual voltage is AC50-500V in a test, which puts extremely high requirements on devices in an AC-DC conversion circuit, such as the withstand voltage of a filter capacitor reaches 600V at 125 ℃, the withstand voltage of an MOS transistor in a PWM circuit reaches 1200V, while the withstand voltage of the current high-temperature capacitor is generally 400V, the withstand voltage of a silicon MOS transistor is at the limit of 950V, and the withstand voltage of a silicon carbide MOS transistor can reach 1200V, but the price is thousands of yuan. If the generator with low voltage and large current is too large and cannot be installed, the high-voltage generator needs to be stepped down by the alternating-current transformer, so that the efficiency is low, temperature rise can be generated, and the generator is large in size and cannot be installed in a drill rod.

Disclosure of Invention

In order to solve the problems, the invention provides a wide-range AC-DC power supply conversion system and a wide-range AC-DC power supply conversion method for a drilling wireless drilling tool, which adopt a high-side and low-side double-BUCK PWM conversion circuit and an impulse voltage-stabilizing transformer to reduce the working voltage of a capacitor and an MOS (metal oxide semiconductor) tube by half, realize AC-DC conversion on AC50-500V voltage output by an underground three-phase generator under the condition of underground wide-range alternating current input, and ensure the stability of the circuit.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a wide range AC-DC power conversion system for a wireless while drilling tool for drilling, comprising: the device comprises a three-phase rectification circuit, a filtering voltage-sharing circuit, a double-side BUCK PWM conversion circuit and an impulse voltage-stabilizing transformer;

the three-phase rectifying circuit is connected with the filtering and voltage-equalizing circuit and is used for rectifying and filtering the three-phase alternating-current voltage and then outputting direct-current voltage;

the filter voltage-sharing circuit is connected with the double-side double-BUCK PWM conversion circuit, the double-side double-BUCK PWM conversion circuit is connected with the impulse voltage-stabilizing transformer, and the double-side double-BUCK PWM conversion circuit comprises a first MOS (metal oxide semiconductor) tube, a second MOS tube, a driving circuit and a PWM conversion circuit;

a first MOS tube and a second MOS tube are respectively connected between the positive pole and the middle point voltage of the filter voltage-sharing circuit and between the middle point voltage and the negative pole, the action of the double MOS tubes is controlled by the driving circuit and the PWM conversion circuit, and when the double MOS tubes do not synchronously act, the double-side coils of the impulse voltage-stabilizing transformer generate induced voltages with the same voltage and opposite polarities so as to keep the double MOS tubes at half voltage and output target voltage after PWM modulation is carried out on the direct current voltage.

In a second aspect, the present invention provides a method for converting a wide-range AC-DC power supply of a wireless drilling tool for drilling, comprising:

rectifying and filtering the obtained three-phase alternating voltage and then outputting direct-current voltage;

the double MOS tubes are controlled to act through a driving circuit and a PWM conversion circuit so as to output target voltage after PWM modulation is carried out on direct-current voltage;

if the double MOS tubes do not act synchronously, the double-side coil of the impulse voltage-stabilizing transformer generates induced voltages with the same voltage and opposite polarities so as to keep the double MOS tubes in a half-voltage state.

Compared with the prior art, the invention has the beneficial effects that:

the invention provides an AC-DC voltage stabilizing system for supplying power to underground high-power instruments in an oil field drilling environment, which creatively uses a high-side and low-side double-BUCK PWM (pulse-width modulation) conversion circuit and an impulse voltage stabilizing transformer to reduce the working voltage of a capacitor and an MOS (metal oxide semiconductor) tube by half, realizes AC-DC conversion and voltage stabilization on AC50-500V voltage output by an underground three-phase generator, outputs a voltage DC200V and an output power 200W, and the output voltage of the generator reaches more than 80V and is in an abnormal working state below 80V, the efficiency reaches 98 percent, and can stably work for a long time in the environment.

The wide-range AC-DC power conversion system of the drilling wireless while-drilling instrument requires the efficiency to be higher than 95%, can reduce the temperature rise, prolong the service life and realize the conversion of high-power AC-DC under the condition of underground wide-range alternating current input.

In the wide-range AC-DC power supply conversion system, the working voltage of the double MOS tubes is half voltage, so that the problem of low voltage resistance of the MOS tubes is solved, and the double MOS tubes synchronously work to realize high-speed on-off switching.

In the wide-range AC-DC power supply conversion system, two filter capacitors with withstand voltage of 400V are connected in series to form a filter voltage-sharing circuit, on one hand, the problem of filtering of 600V high voltage is solved, direct current pulsating voltage is filtered into direct current voltage, and on the other hand, the midpoint voltage is extracted from the midpoint of the two filter capacitors connected in series.

In the wide-range AC-DC power supply conversion system, when the double MOS tubes do not act synchronously, namely one MOS tube is conducted, and the other MOS tube is cut off or semi-conducted, the double MOS tubes are kept at half voltage by generating induced voltages with the same voltage and opposite polarities through the double-side coils of the impulse voltage stabilizing transformer, so that the midpoint potential is kept constant, and the problem that the MOS tubes which are not conducted are damaged due to voltage breakdown is solved.

Advantages of additional aspects of the 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.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 is a block diagram of a wide-range AC-DC power conversion system of a wireless while drilling instrument for drilling provided in embodiment 1 of the present invention;

the circuit comprises a three-phase rectifier diode group 1, a three-phase rectifier diode group 2, a filter capacitor 3, a high-side MOS (metal oxide semiconductor) transistor 4, a low-side MOS transistor 5, a high-side freewheeling diode 6, a low-side freewheeling diode 7, a driving circuit 8, a PWM (pulse-width modulation) conversion circuit 9, a differential mode impulse voltage stabilizing transformer 10, a sampling circuit 11 and an output end filter voltage-sharing capacitor.

The specific implementation mode is as follows:

the invention is further described with reference to the following figures and examples.

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise, and it should be understood that the terms "comprises" and "comprising", and any variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

The embodiments and features of the embodiments of the present invention may be combined with each other without conflict.

Example 1

As shown in fig. 1, the present embodiment provides a wide-range AC-DC power conversion system of a wireless drilling tool for drilling, comprising: the device comprises a three-phase rectification circuit, a filtering voltage-sharing circuit, a double-side double-BUCK PWM conversion circuit, an impulse voltage-stabilizing transformer, a sampling circuit and a high-frequency filtering circuit;

the three-phase rectifying circuit is connected with the filtering and voltage-equalizing circuit and rectifies and converts three-phase alternating-current voltage output by the generator to output direct-current pulsating voltage to the filtering and voltage-equalizing circuit;

the filter voltage-sharing circuit is used for filtering the direct current pulsating voltage and outputting the direct current voltage.

In the embodiment, the three-phase rectification circuit comprises a three-phase rectification diode group 1, and is used for rectifying the three-phase alternating voltage of 50-500V output by the generator into direct current pulsating voltage;

the filter voltage-sharing circuit comprises two filter capacitors 2 connected in series, on one hand, the filter voltage-sharing circuit solves the problem of filtering of 600V high voltage and filters direct current pulsating voltage into direct current voltage, on the other hand, midpoint voltage is established for the direct current voltage which is not stabilized, and midpoint voltage, namely half voltage, of the direct current voltage is obtained at the midpoint of the two filter capacitors 2 connected in series.

Preferably, the filter capacitor 2 is resistant to a voltage of 400V.

The filter voltage-sharing circuit is connected with the double-side BUCK PWM conversion circuit, and the double-side BUCK PWM conversion circuit is connected with the impulse voltage-stabilizing transformer; the double-side double-BUCK PWM conversion circuit comprises a first MOS tube, a second MOS tube, a driving circuit, a PWM conversion circuit, a first diode and a second diode;

a first MOS tube and a second MOS tube are respectively connected between the positive pole and the middle point voltage of the filter voltage-sharing circuit and between the middle point voltage and the negative pole, the action of the double MOS tubes is controlled by the driving circuit and the PWM conversion circuit, and when the double MOS tubes do not synchronously act, the double-side coils of the impulse voltage-stabilizing transformer generate induced voltages with the same voltage and opposite polarities so as to keep the double MOS tubes at half voltage and output target voltage after PWM modulation is carried out on the direct current voltage.

In the embodiment, the double-side double-BUCK PWM conversion circuit establishes a two-stage PWM conversion circuit between the positive voltage, the middle voltage and the negative voltage (ground) of the filter voltage-sharing circuit, the Vds working voltage of the double MOS tubes is half voltage, the problem of low voltage resistance of the MOS tubes is solved, and the double MOS tubes synchronously work to realize high-speed on-off switching.

Preferably, the first MOS transistor and the second MOS transistor are both N-channel transistors.

Preferably, the first MOS transistor and the second MOS transistor correspond to the high-side MOS transistor 3 and the low-side MOS transistor 4 shown in fig. 1; the high-side MOS tube 3 and the low-side MOS tube 4 are controlled by a driving circuit 7 and a PWM (pulse-width modulation) conversion circuit 8, and the high-side MOS tube 3 and the low-side MOS tube 4 are controlled to synchronously realize pulse width modulation high-speed on-off switching according to input voltage and load change.

Preferably, a first diode and a second diode, namely a high-side freewheeling diode 5 and a low-side freewheeling diode 6, are connected between the high-side MOS transistor 3 and the low-side MOS transistor 4 for realizing freewheeling in the switching process of the MOS transistors and ensuring the stability of the circuit.

Because the double MOS tubes cannot be completely and synchronously switched on and off, when one MOS tube is switched on and the other MOS tube is switched off or semi-conducted at a certain moment, the midpoint can deviate even to be the highest value or 0 under the action of current, and the Vds of the MOS tube which is not switched on is equal to full voltage and can be immediately damaged;

therefore, in this embodiment, an impulse voltage stabilizing transformer, i.e. a differential mode impulse voltage stabilizing transformer 9, is used, and is a high frequency transformer, when the high side MOS transistor 3 and the low side MOS transistor 4 are not completely synchronized, such as one MOS transistor is turned on, and the other MOS transistor is turned off or semi-conducted, the current in the transformer coil connected to the turned-on MOS transistor increases rapidly, and its counter electromotive force increases immediately, generating a voltage across the coil; according to the characteristics of the transformer, induced voltages with the same voltage value and opposite polarities are induced at two ends of the other group of coils and used for stabilizing the voltages at two ends of the main circuit, the stability of the midpoint voltage is ensured, the Vds voltage of the high-side MOS tube 3 and the low-side MOS tube 4 is in half voltage, and the damage caused by voltage breakdown is avoided.

Preferably, the two groups of coils of the differential mode impulse voltage-stabilizing transformer 9 have the same number of turns and the same wire diameter, and the ends with the same name are opposite; meanwhile, due to the fact that the homonymous ends are opposite, the voltages of the two coils are mutually offset after being connected in series through the load, the work of the other MOS tube cannot be influenced, the midpoint potential can be kept constant, and when the two MOS tubes are conducted, the circuit is in a symmetrical state and works in voltage sharing mode.

In this embodiment, the sampling circuit 10 is connected to a high-frequency filter circuit, the high-frequency filter circuit is composed of an output-end filter voltage-sharing capacitor, a target output voltage value is determined according to the sampling circuit, and the target dc voltage is output after the dc voltage modulated by PWM is filtered according to the high-frequency filter circuit.

Preferably, the output end of the high-frequency filter circuit filters the voltage-sharing capacitor, on one hand, filtering of the high-frequency voltage is achieved, and on the other hand, an output voltage midpoint is established, so that establishment of the high-side and low-side feedback circuits is met, and circuit balance is achieved.

In further embodiments, there is also provided an implementation method of the above wide-range AC-DC power conversion system for a wireless drilling tool for drilling, which is used for AC-DC converting an output voltage of a downhole three-phase generator, and includes:

rectifying and filtering the obtained three-phase alternating voltage and then outputting direct-current voltage;

the double MOS tubes are controlled to act through a driving circuit and a PWM conversion circuit so as to output target voltage after PWM modulation is carried out on direct-current voltage;

if the double MOS tubes do not act synchronously, the double-side coil of the impulse voltage-stabilizing transformer generates induced voltages with the same voltage and opposite polarities so as to keep the double MOS tubes in a half-voltage state.

The embodiment provides an AC-DC voltage stabilizing system for supplying power to underground high-power instruments in an oil field drilling environment, AC-DC conversion and voltage stabilization are realized on AC50-500V voltage output by an underground three-phase generator, the output voltage DC200V and the output power 200W are realized, the output voltage of the generator reaches more than 80V and is in an abnormal working state below 80V, and the efficiency reaches 98%.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, it is not intended to limit the scope of the present invention, and it should be understood by those skilled in the art that various modifications and variations can be made without inventive efforts by those skilled in the art based on the technical solution of the present invention.