Mining piezoelectric type vibration energy synchronous extraction circuit and method

Abstract

The invention discloses a mining piezoelectric type vibration energy synchronous extraction circuit and method. The mining piezoelectric type vibration energy synchronous extraction circuit comprises a piezoelectric module, a synchronous switch module, an active rectification circuit module, a current zero-cross detection circuit module and an energy storage capacitor, two ends of the piezoelectric module are connected with positive and negative input ends of the active rectification circuit module; the energy storage capacitor is connected in parallel with a positive output end of the active rectification circuit module; the synchronous switch module is arranged between the piezoelectric module and the active rectification circuit module, and when the current zero-crossing detection circuit module detects a zero-crossing point of a current source in the piezoelectric module in real time, the synchronous switch module is controlled to be switched on; and when the absolute value of the input end voltage of the active rectification current module is greater than the conduction threshold value of the bridge arm switch tube corresponding to the active rectification current circuit module, the synchronous switch module is controlled to be cut off. According to the invention, the conversion efficiency of vibration piezoelectric energy is greatly improved, and the defect that a traditional diode rectification energy-taking circuit cannot be reliably used is overcome.

Description

Technical Field

[0001] The present invention relates to the field of coal mine monitoring and surveillance, and in particular to a piezoelectric vibration energy synchronous extraction circuit and method for mining. Background Art

[0002] Coal mine motors are mainly used to drive various mechanical equipment in coal mines, such as mining machinery, transportation equipment, ventilation equipment and drainage equipment, etc., which provide guarantee for efficient and safe production of coal mines. Therefore, it is of great significance to carry out condition monitoring and fault diagnosis of motor equipment, realize the transition from "after-the-fact maintenance" to "predictive maintenance", and avoid unexpected downtime and serious accidents.

[0003] Using vibration and temperature signals to monitor and diagnose motor equipment is the most common and effective method for equipment fault diagnosis. At present, the main method for extracting motor vibration and temperature signals is to use mining vibration and temperature sensors. Sensors are divided into wired-powered sensors and battery-powered sensors according to the power supply method. Wired-powered sensors have problems such as complex on-site installation and limited usage scenarios, especially on mobile airborne equipment; battery-powered sensors have problems such as short battery life, frequent replacement, and large overall size.

[0004] With the widespread application of ultra-low power and micro-packaged electronic devices and radio frequency modules in coal mines, piezoelectric vibration energy harvesting technology has been developed. Piezoelectric vibration energy harvesting technology is to convert vibration energy in the external environment, such as the vibration energy generated by the operation of the motor, into electrical energy using the piezoelectric effect of piezoelectric elements, and store it, and finally power the wireless sensor network or small electrical equipment. At present, the energy harvesting circuit of the piezoelectric vibration energy harvesting sensor for mining usually adopts the traditional full-bridge rectifier circuit, such as Figure 1 shown.

[0005] The piezoelectric vibration energy harvesting circuit consists of a piezoelectric element, a full-bridge rectifier circuit, and an energy storage capacitor. The piezoelectric equivalent model of the piezoelectric element consists of a current source (ip(t) = IpSin(ωt), where Ip is the current amplitude and ω is the vibration angular frequency), a piezoelectric capacitor Cp, and a loss resistor Rp in parallel; the full-bridge rectifier circuit uses four diodes as rectifier tubes; the energy storage capacitor C L The supercapacitor is used as an energy storage element to provide energy to the subsequent load or rechargeable battery. This circuit has the following disadvantages:

[0006] (1) The diode rectifier used in the rectifier circuit has a high conduction voltage drop, which directly affects the range of electrical energy extracted from the piezoelectric element. At the same time, the power consumption of the rectifier circuit itself is also relatively large. Therefore, the rectification efficiency of the traditional full-bridge rectifier circuit is relatively low.

[0007] (2) The piezoelectric current ip(t) generated by the vibration of the piezoelectric element is a sine wave. In each cycle, there are three regions: discharge, charge, and conversion, such as Figure 2 When the current reverses, the original charge on Cp must be neutralized first (discharge area), and then the capacitor Cp is reversely charged by the current ip(t) (charge area). In these two areas, the full-bridge rectifier diodes are in the cut-off state. Only when V PN The absolute value of (the voltage across capacitor Cp) is greater than the threshold voltage V of the rectifier bridge th When one of the bridge arms of the rectifier bridge is turned on, the load capacitor C L Charging (conversion zone) until the direction of the current ip(t) changes again. In the whole cycle, two discharges are performed. Due to the existence of the discharge zone, the charge is lost, part of the energy is wasted, and the energy capture efficiency of the circuit is reduced.

[0008] Due to the above-mentioned shortcomings of the traditional full-bridge rectifier circuit, the energy-harvesting circuit cannot provide sufficient energy to the subsequent load in actual application, resulting in problems such as the mine wireless vibration and temperature sensors not being able to work properly, the wireless transmission interval being too long, and the need for backup batteries to assist in power supply. Summary of the invention

[0009] In order to solve the technical problems in the prior art that the mining piezoelectric vibration energy extraction efficiency is low and cannot provide sufficient energy to the subsequent load, resulting in the mining wireless vibration and temperature sensors not being able to work properly and the wireless transmission interval being too long, the present invention proposes a mining piezoelectric vibration energy synchronous extraction circuit and method.

[0010] In order to solve the above technical problems, the present invention specifically adopts the following technical solutions.

[0011] A piezoelectric vibration energy synchronous extraction circuit for mining, comprising a piezoelectric module, a synchronous switch module, an active rectification circuit module, a current zero-crossing detection circuit module, and an energy storage capacitor; characterized in that:

[0012] The piezoelectric module includes a current source, and a piezoelectric capacitor and a loss resistor connected in parallel with both ends of the current source;

[0013] Two ends of the piezoelectric module are connected to the positive and negative input ends of the active rectifier circuit module, and the energy storage capacitor is connected in parallel to the positive output end of the active rectifier circuit module;

[0014] The synchronous switch module is arranged between the piezoelectric module and the active rectification circuit module. When the current zero-crossing detection circuit module detects the zero-crossing point of the current source in the piezoelectric module in real time, the synchronous switch module is controlled to be turned on until the absolute value of the voltage at the input end of the active rectification current module is greater than the conduction threshold of the corresponding bridge arm switch tube of the active rectification current circuit module, and then the synchronous switch module is controlled to be turned off.

[0015] The present invention further includes the following preferred embodiments.

[0016] The active rectification current circuit module is a full-bridge rectification circuit, wherein the upper half bridge and the lower half bridge are both composed of two MOS tubes, wherein the two MOS tubes of the upper half bridge are cross-coupled and connected, and the two MOS tubes of the lower half bridge form an active pair tube structure.

[0017] More preferably,

[0018] The upper half bridge of the active rectifier current module is composed of a first P-MOS tube QP1 and a second P-MOS tube QP2. The drain of the first P-MOS tube QP1 is connected to an output terminal P of the piezoelectric module, the drain of the second P-MOS tube QP2 is connected to another output terminal N of the piezoelectric module, and the source of the first P-MOS tube QP1 and the second P-MOS tube QP2 are connected to the positive voltage terminal of the energy storage capacitor.

[0019] The gate of the first P-MOS transistor QP1 is connected to the drain of the second P-MOS transistor QP2 , and the gate of the second P-MOS transistor QP2 is connected to the drain of the first P-MOS transistor QP1 .

[0020] More preferably,

[0021] The lower half bridge of the active rectification current circuit module includes a first N-MOS tube QN1, a second N-MOS tube QN2, a first comparator CMP1, and a second comparator CMP2; the first N-MOS tube QN1 and the first comparator CMP1 form a first active switch tube of the lower half bridge, and the second N-MOS tube QN2 and the second comparator CMP2 form a second active switch tube of the lower half bridge;

[0022] The first P-MOS transistor QP1 of the upper half bridge and the second active switch transistor of the lower half bridge form a first bridge arm;

[0023] The second P-MOS transistor QP2 of the upper half bridge and the first active switch transistor of the lower half bridge form a second bridge arm.

[0024] More preferably,

[0025] The lower half bridge of the active rectification current circuit module includes a first N-MOS tube QN1, a second N-MOS tube QN2, a first comparator CMP1, and a second comparator CMP2;

[0026] The positive input terminal of the first comparator CMP1 is connected to the source of the first N-MOS transistor QN1, the negative input terminal of the first comparator CMP1 is connected to the drain of the first N-MOS transistor QN1, and the output terminal of the first comparator CMP1 is connected to the gate of the first N-MOS transistor QN1;

[0027] The positive input terminal of the second comparator CMP2 is connected to the source of the second N-MOS transistor QN2, the negative input terminal of the second comparator CMP2 is connected to the drain of the second N-MOS transistor QN2, and the output terminal of the second comparator CMP2 is connected to the gate of the second N-MOS transistor QN2;

[0028] The drain of the first N-MOS tube QN1 is connected to the drain of the first P-MOS tube QP1, and the drain of the second N-MOS tube QN2 is connected to the drain of the second P-MOS tube QP2; the source of the first N-MOS tube QN1 and the source of the second N-MOS tube QN2 are both connected to the other output end (N) of the piezoelectric module and the positive voltage end of the energy storage capacitor.

[0029] More preferably,

[0030] The input end of the current zero-crossing detection circuit module is connected to the gate of the first N-MOS transistor QN1 and the gate of the second N-MOS transistor QN2, and the output end of the current zero-crossing detection circuit module is connected to the control end of the synchronous switch module;

[0031] When the gate of the first N-MOS transistor QN1 and the gate of the second N-MOS transistor QN2 are both at low level, it is determined that the current source current ip(t) in the piezoelectric module passes through zero, and the synchronous switch circuit is controlled to be turned on.

[0032] More preferably,

[0033] The current zero-crossing detection circuit module includes a first NOR gate NOR1, a second NOR gate NOR2, a first NOT gate NOT1, a second NOT gate NOT2, a third NOT gate NOT3, a fourth NOT gate NOT4, a first RC filter circuit and a second RC filter circuit;

[0034] The gate of the first N-MOS transistor QN1 and the gate of the second N-MOS transistor QN2 are respectively connected to the two input ends of the first NOR gate NOR1, the input end of the first NOR gate NOR1 is connected to the input end of the first NOT gate NOT1, the output end of the first NOT gate NOT1 is respectively connected to the input end of the second NOT gate NOT2 and one input end of the second NOR gate NOR2 after passing through the first RC filtering circuit, the output end of the second NOT gate NOT2 is connected to the input end of the third NOT gate NOT3 after passing through the second RC filtering circuit, the output end of the third NOT gate NOT3 is connected to the other input end of the second NOR gate NOR2, the output end of the second NOR gate NOR2 is connected to the input end of the fourth NOT gate NOT4, and the output end of the fourth NOT gate NOT4 is connected to the control end connected to the synchronous switch module.

[0035] More preferably,

[0036] The synchronous switch circuit is composed of two P-MOS switch tubes connected in series, the circuit is connected across the piezoelectric element and the rectifier circuit, and the output end of the fourth NOT gate NOT4 of the current zero-crossing detection circuit module is connected to the gates of the two P-MOS switch tubes connected in series;

[0037] When it is determined that the current ip(t) passes through the zero point, the current zero-crossing detection circuit module outputs a low level, controls the switch tube to be turned on, and the piezoelectric capacitor discharges to the ground.

[0038] The present application also claims protection for a mining piezoelectric vibration energy synchronous extraction method based on the energy synchronous extraction circuit, the extraction method comprising:

[0039] S1: The amplitude of the piezoelectric module current source ip(t) gradually increases from zero, and 0<V AB <|V th |, the current zero-crossing detection circuit module outputs a low-level signal to control the synchronous switch module to turn on, and the piezoelectric capacitor in the piezoelectric module discharges; where V AB is the voltage difference between the upper and lower half bridge junctions of the active rectifier current circuit module, which is equal to the voltage value across the piezoelectric module, V th is the upper arm threshold voltage of the active rectifier circuit module;

[0040] S2: The amplitude of the current source ip(t) continues to increase. When V AB ≥|V th |, the current zero-crossing detection circuit module outputs a high-level signal to control the synchronous switch module to be cut off, and the piezoelectric module charges the energy storage capacitor through the active rectifier circuit module;

[0041] S3: The amplitude of the current source ip(t) gradually decreases from zero, V AB <0 and |V AB |<|V th |, the charging stops, and the current zero-crossing detection circuit module outputs a low-level signal to control the synchronous switch module to turn on, and the piezoelectric capacitor in the piezoelectric module discharges;

[0042] S4: The amplitude of the current source ip(t) continues to decrease. When |V AB |≥|V th |, the current zero-crossing detection circuit module outputs a high-level signal to control the synchronous switch module to be cut off, and the piezoelectric module charges the energy storage capacitor through the active rectifier circuit module.

[0043] The present invention has the following beneficial technical effects:

[0044] (1) The present invention utilizes synchronous switch control technology to close the synchronous switch at the moment when the equivalent current source of the piezoelectric element is reversed, that is, when the current passes through the zero point, so that the charge stored on the piezoelectric capacitor Cp is released instantly, avoiding reverse neutralization of the voltage on the piezoelectric capacitor, skipping the discharge area, and directly reverse charging, thereby reducing energy loss, greatly improving the conversion efficiency of vibration piezoelectric energy, and making up for the deficiency that the traditional diode rectification energy-taking circuit cannot be used reliably.

[0045] (2) The present invention uses P-MOS tubes and N-MOS tubes with ultra-low on-resistance Rds(on) and adopts a cross-coupling method to form a rectifier circuit, which reduces the on-state voltage drop of the rectifier tube, can reduce the power consumption of the rectifier circuit itself, increase the conduction angle, and expand the range of electric energy extraction. Through the above measures and methods, most of the charge obtained from the piezoelectric element can enter the load capacitor C L The device can significantly reduce the charge loss and greatly improve the energy conversion efficiency of the circuit. It can provide complete and stable power supply for wireless vibration and temperature sensors for mining, and can also replace battery power supply, thereby effectively reducing the volume of wireless vibration and temperature sensors for mining, which is more conducive to on-site installation and long-term use of sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a traditional piezoelectric vibration energy extraction circuit diagram;

[0047] Figure 2 This is the theoretical waveform diagram of the traditional piezoelectric vibration energy extraction front-end circuit;

[0048] Figure 3 It is a circuit diagram for synchronous extraction of piezoelectric vibration energy;

[0049] Figure 4 This is the structure and simplified diagram of the active diode;

[0050] Figure 5 This is the waveform diagram of the piezoelectric vibration energy synchronous extraction circuit. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only part of the embodiments of the present invention, not all of them. Based on the spirit of the present invention, other embodiments obtained by ordinary technicians in this field without creative work are all within the scope of protection of the present invention.

[0054] The invention discloses a mining piezoelectric vibration energy synchronous extraction circuit. Figure 3As shown, the circuit consists of a piezoelectric element, an active rectification circuit, a synchronous switching circuit, a current zero-crossing detection circuit and an energy storage capacitor.

[0055] The piezoelectric module includes a current source, and a piezoelectric capacitor and a loss resistor connected in parallel with both ends of the current source;

[0056] Two ends of the piezoelectric module are connected to the positive and negative input ends of the active rectifier circuit module, and the energy storage capacitor is connected in parallel to the positive output end of the active rectifier circuit module;

[0057] The synchronous switch module is arranged between the piezoelectric module and the active rectification circuit module. When the current zero-crossing detection circuit module detects the zero-crossing point of the current source in the piezoelectric module in real time, the synchronous switch module is controlled to be turned on until the absolute value of the voltage at the input end of the active rectification current module is greater than the conduction threshold of the corresponding bridge arm switch tube of the active rectification current circuit module, and then the synchronous switch module is controlled to be turned off.

[0058] The working principle of each module and the whole is as follows: Piezoelectric element

[0059] The output energy density of the piezoelectric element is high, and only slight mechanical deformation can obtain a large amount of AC power. Its piezoelectric equivalent model consists of a current source (ip(t) = IpSin(ωt), where Ip is the current amplitude and ω is the vibration angular frequency), a piezoelectric capacitor Cp and a loss resistor Rp in parallel. The AC power output by the piezoelectric element must be rectified by the rectifier module before it can be output to the subsequent voltage regulator module and load.

[0060] Active rectifier circuit module

[0061] The active rectifier circuit is a full-bridge rectifier circuit, which is divided into an upper half bridge and a lower half bridge. The upper half bridge is composed of two P-MOS tubes QP1 and QP2, which are a cross-coupled tube structure; the lower half bridge is composed of two N-MOS tubes QN1 and QN2 and two comparators CMP1 and CMP2, which are active diode tube structures. QN1 and CMP1, QN2 and CMP2 respectively form two active diodes. The structure and use of active diodes are shown in the figure below. Figure 4 As shown, the specific circuit structure is as follows:

[0062] The upper half bridge of the active rectifier current module is composed of a first P-MOS tube QP1 and a second P-MOS tube QP2. The drain of the first P-MOS tube QP1 is connected to an output terminal P of the piezoelectric module, the drain of the second P-MOS tube QP2 is connected to another output terminal N of the piezoelectric module, and the source of the first P-MOS tube QP1 and the second P-MOS tube QP2 are connected to the positive voltage terminal of the energy storage capacitor.

[0063] The first P-MOS transistor QP1 of the upper half bridge and the second active switch transistor of the lower half bridge form a first bridge arm, and the second P-MOS transistor QP2 of the upper half bridge and the first active switch transistor of the lower half bridge form a second bridge arm.

[0064] The gate of the first P-MOS transistor QP1 is connected to the drain of the second P-MOS transistor QP2 , and the gate of the second P-MOS transistor QP2 is connected to the drain of the first P-MOS transistor QP1 .

[0065] The positive input terminal of the first comparator CMP1 is connected to the source of the first N-MOS transistor QN1, the negative input terminal of the first comparator CMP1 is connected to the drain of the first N-MOS transistor QN1, and the output terminal of the first comparator CMP1 is connected to the gate of the first N-MOS transistor QN1;

[0066] The positive input terminal of the second comparator CMP2 is connected to the source of the second N-MOS transistor QN2, the negative input terminal of the second comparator CMP2 is connected to the drain of the second N-MOS transistor QN2, and the output terminal of the second comparator CMP2 is connected to the gate of the second N-MOS transistor QN2;

[0067] The drain of the first N-MOS tube QN1 is connected to the drain of the first P-MOS tube QP1, and the drain of the second N-MOS tube QN2 is connected to the drain of the second P-MOS tube QP2; the source of the first N-MOS tube QN1 and the source of the second N-MOS tube QN2 are both connected to the other output end (N) of the piezoelectric module and the positive voltage end of the energy storage capacitor.

[0068] The main functions of the active diode in the rectifier bridge are: ① Using the clamping effect of the comparator to significantly reduce the conduction voltage drop of QN1 and QN2; ② Using the sensitivity of the comparator to detect the slight voltage drop between the drain and source of the N-MOS tube to control the conduction or shutdown of the N-MOS tube; ③ Preventing reverse leakage current from being generated at the output end of the rectifier circuit.

[0069] In the active rectifier circuit, QP1 and the active diode (QN2, CMP2) form a bridge arm (hereinafter referred to as bridge arm 1), and QP2 and the active diode (QN1, CMP1) form another bridge arm (hereinafter referred to as bridge arm 2). When VAB>0 and higher than the absolute value voltage of the bridge arm threshold, bridge arm 1 is turned on and bridge arm 2 is turned off; when VAB<0 and the absolute value voltage is lower than the absolute value voltage of the bridge arm threshold, bridge arm 2 is turned on and bridge arm 1 is turned off.

[0070] Current zero-crossing detection circuit module

[0071] The current zero-crossing detection circuit module consists of two NOR gates NOR1 and NOR2 and four NOT gates NOT1, NOT2, NOT3, NOT4 and second-order RC filter circuits R1, C11, R2, and C12. The zero point of the current ip(t) is determined by detecting the output signal of the comparator in the active diode. The falling edges of the output signals VC1 and VC2 of the comparators CMP1 and CMP2 are both the zero points of the current ip(t). When a falling edge appears in a comparator, the current zero-crossing detection circuit outputs a low level, that is, the control input terminal D of the synchronous switch circuit is a low level, and the synchronous switch SW is turned on.

[0072] The specific structure of the current zero-crossing detection circuit can be found in Figure 3 The gate of the first N-MOS transistor QN1 and the gate of the second N-MOS transistor QN2 are respectively connected to the two input ends of the first NOR gate NOR1, the input end of the first NOR gate NOR1 is connected to the input end of the first NOT gate NOT1, the output end of the first NOT gate NOT1 is respectively connected to the input end of the second NOT gate NOT2 and one input end of the second NOR gate NOR2 after passing through the first RC filtering circuit, the output end of the second NOT gate NOT2 is connected to the input end of the third NOT gate NOT3 after passing through the second RC filtering circuit, the output end of the third NOT gate NOT3 is connected to the other input end of the second NOR gate NOR2, the output end of the second NOR gate NOR2 is connected to the input end of the fourth NOT gate NOT4, and the output end of the fourth NOT gate NOT4 is connected to the control end connected to the synchronous switch module.

[0073] The logic control relationship of the current zero-crossing detection circuit is shown in Table 1.

[0074] Table 1

[0075]

[0076] Synchronous switching circuit

[0077] The synchronous switch circuit consists of two P-MOS switch tubes connected in series, namely QP-SW1 and QP-SW2. The circuit is connected between the piezoelectric element and the rectifier circuit. When the current ip(t) passes through the zero point, the current zero-crossing detection circuit outputs a low level, controls the switch tube to turn on, and the piezoelectric capacitor Cp discharges to the ground; when the capacitor Cp discharges to zero, the switch tube is turned off.

[0078] The synchronous switching circuit is composed of two P-MOS switching tubes connected in series. The circuit is connected between the piezoelectric element and the rectifier circuit. The output end of the fourth NOT gate NOT4 of the current zero-crossing detection circuit module is connected to the gates of the two P-MOS switching tubes connected in series. When it is judged that the current ip(t) passes through the zero point, the current zero-crossing detection circuit module outputs a low level, controls the switch tube to be turned on, and the piezoelectric capacitor discharges to the ground.

[0079] Energy storage capacitor

[0080] The energy storage capacitor CL is a supercapacitor, which has high charging efficiency and long service life and can store energy for subsequent circuits well.

[0081] The working process of the mining piezoelectric vibration energy synchronous extraction circuit disclosed in the present invention is as follows:

[0082] The waveform of the piezoelectric vibration energy synchronous extraction circuit is as follows: Figure 5 As shown. In a single cycle of the equivalent current source ip(t), four intervals are divided: t0~t1 is the upward zero-crossing interval; t1~t2 is the positive half-cycle charging conversion interval; t2~t3 is the downward zero-crossing interval; t3~t4 is the negative half-cycle charging conversion interval. Their working logic is as follows:

[0083] Crossing the zero range upward.

[0084] In this interval, the amplitude of the equivalent current source ip(t) gradually increases from zero, and 0<VAB<|Vth|, Vth is the threshold voltage of bridge arm 1 and bridge arm 2 (the two bridge arms are a pair of tube structures with similar parameters). In bridge arm 1, the P-MOS tube QP1 is in the cut-off state. Since VB>0, the comparator CMP2 outputs VC2 at a low level, and the N-MOS tube QN2 is also in the cut-off state; in bridge arm 2, the P-MOS tube QP2 is in the cut-off state. Since VA>0, the comparator CMP1 outputs VC1 at a low level, and the N-MOS tube QN1 is also in the cut-off state. Since VC1 and VC2 are both low levels, the current zero-crossing detection circuit outputs a low level at node D, and the control switch SW is turned on, quickly discharging the charge generated on the capacitor Cp in the negative half cycle of the previous cycle, avoiding energy loss caused by neutralizing the charge in Cp during the positive half cycle of the cycle. In this interval, the load capacitor CL supplies power to the subsequent load.

[0085] Positive half-cycle charging conversion range.

[0086] As the equivalent current source ip(t) continues to flow into the capacitor Cp, the voltage VAB gradually increases. When VAB≥|Vth|, the P-MOS tube QP1 in the bridge arm 1 is turned on, which can be regarded as a short circuit between the node A and the node E. After that, V AB Continue to increase, because in the steady state, the voltage values ​​of node A and node E remain basically unchanged, so V AB The increase in V will cause the voltage at node B to drop. B ≤0, the comparator CMP2 outputs V C2 is high level, because V C2 is high level, the current zero-crossing detection circuit outputs a high level at node D, and the control switch SW is turned off; in bridge arm 2, the P-MOS tube QP2 is in the off state, because V A>0, comparator CMP1 outputs V C1 is low level, and the N-MOS tube QN1 is also in the cut-off state. In this interval, the capacitor Cp provides the load capacitor C L Charge and supply power to the subsequent loads.

[0087] Downward zero crossing.

[0088] In this interval, the amplitude of the equivalent current source ip(t) gradually decreases from zero, V AB <0 and |V AB |<|V th |. In bridge arm 1, P-MOS tube QP1 is in the cut-off state, because V B >0, comparator CMP2 outputs V C2 is low level, the N-MOS tube QN2 is also in the cut-off state; in bridge arm 2, the P-MOS tube QP2 is in the cut-off state, because V A >0, comparator CMP1 outputs V C1 is low level, and the N-MOS tube QN1 is also in the cut-off state. C1 and V C2 The current zero-crossing detection circuit outputs a low level at node D, controls the switch SW to turn on, and quickly discharges the charge generated on the capacitor Cp in the positive half cycle, avoiding energy loss caused by neutralizing the charge in Cp in the negative half cycle. L Provide power to the subsequent loads.

[0089] Negative half cycle charging conversion range.

[0090] As the amplitude of the equivalent current source ip(t) continues to decrease, when |V AB |≥|V th |, in bridge arm 2, P-MOS tube QP2 is turned on, which can be regarded as a short circuit between node B and node E. After that, V AB Continue to decrease, because in the steady state, the voltage values ​​of node B and node E remain basically unchanged, so V AB The decrease in V will cause the voltage at node A to drop. A ≤0, the comparator CMP1 outputs V C1 is high level, because V C1 High level, the current zero-crossing detection circuit outputs a high level at node D, and the control switch SW is turned off; in bridge arm 1, the P-MOS tube QP1 is in the off state, because V B >0, comparator CMP2 outputs V C2 is low level, and the N-MOS tube QN2 is also in the cut-off state. In this interval, the capacitor Cp provides the load capacitor C L Charge and supply power to the subsequent loads.

[0091] The working logic of the whole circuit is summarized in Table 2.

[0092] Table 2

[0093]

[0094]

[0095] The present application also discloses a mining piezoelectric vibration energy synchronous extraction method based on the energy synchronous extraction circuit, the extraction method comprising:

[0096] S1: The amplitude of the piezoelectric module current source ip(t) gradually increases from zero, and 0<V AB <|V th |, the current zero-crossing detection circuit module outputs a low-level signal to control the synchronous switch module to turn on, and the piezoelectric capacitor in the piezoelectric module discharges; where V AB is the voltage difference between the upper and lower half bridge junctions of the active rectifier current circuit module, which is equal to the voltage value across the piezoelectric module, V th is the upper arm threshold voltage of the active rectifier circuit module;

[0097] S2: The amplitude of the current source ip(t) continues to increase. When V AB ≥|V th |, the current zero-crossing detection circuit module outputs a high-level signal to control the synchronous switch module to be cut off, and the piezoelectric module charges the energy storage capacitor through the active rectifier circuit module;

[0098] S3: The amplitude of the current source ip(t) gradually decreases from zero, V AB <0 and |V AB |<|V th |, the charging stops, and the current zero-crossing detection circuit module outputs a low-level signal to control the synchronous switch module to turn on, and the piezoelectric capacitor in the piezoelectric module discharges;

[0099] S4: The amplitude of the current source ip(t) continues to decrease. When |V AB |≥|V th |, the current zero-crossing detection circuit module outputs a high-level signal, controls the synchronous switch module to be cut off, and the piezoelectric module charges the energy storage capacitor through the active rectifier circuit module. The present disclosure may be a system, method and / or computer program product. The computer program product may include a computer-readable storage medium on which computer-readable program instructions are loaded for causing a processor to implement various aspects of the present disclosure.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A piezoelectric vibration energy synchronous extraction circuit for mining, comprising a piezoelectric module, a synchronous switch module, an active rectification circuit module, a current zero-crossing detection circuit module, and an energy storage capacitor; characterized in that: The piezoelectric module includes a current source, and a piezoelectric capacitor and a loss resistor connected in parallel with both ends of the current source; Two ends of the piezoelectric module are connected to the positive and negative input ends of the active rectifier circuit module, and the energy storage capacitor is connected in parallel to the positive output end of the active rectifier circuit module; The synchronous switch module is arranged between the piezoelectric module and the active rectification circuit module. When the current zero-crossing detection circuit module detects the zero-crossing point of the current source in the piezoelectric module in real time, the synchronous switch module is controlled to be turned on until the absolute value of the voltage at the input end of the active rectification current module is greater than the conduction threshold of the corresponding bridge arm switch tube of the active rectification current circuit module, and then the synchronous switch module is controlled to be turned off.

2. According to claim 1, the piezoelectric vibration energy synchronous extraction circuit for mining is characterized in that: The active rectification current circuit module is a full-bridge rectification circuit, wherein the upper half bridge and the lower half bridge are both composed of two MOS tubes, wherein the two MOS tubes of the upper half bridge are cross-coupled and connected, and the two MOS tubes of the lower half bridge form an active pair tube structure.

3. According to claim 2, the mining piezoelectric vibration energy synchronous extraction circuit is characterized in that: The upper half bridge of the active rectifier current module is composed of a first P-MOS tube QP1 and a second P-MOS tube QP2. The drain of the first P-MOS tube QP1 is connected to an output end (P) of the piezoelectric module, the drain of the second P-MOS tube QP2 is connected to another output end (N) of the piezoelectric module, and the source of the first P-MOS tube QP1 and the second P-MOS tube QP2 are connected to the positive voltage end of the energy storage capacitor. The gate of the first P-MOS transistor QP1 is connected to the drain of the second P-MOS transistor QP2 , and the gate of the second P-MOS transistor QP2 is connected to the drain of the first P-MOS transistor QP1 .

4. The mining piezoelectric vibration energy synchronous extraction circuit according to claim 3 is characterized in that: The lower half bridge of the active rectification current circuit module includes a first N-MOS tube QN1, a second N-MOS tube QN2, a first comparator CMP1, and a second comparator CMP2; the first N-MOS tube QN1 and the first comparator CMP1 form a first active switch tube of the lower half bridge, and the second N-MOS tube QN2 and the second comparator CMP2 form a second active switch tube of the lower half bridge; The first P-MOS transistor QP1 of the upper half bridge and the second active switch transistor of the lower half bridge form a first bridge arm; The second P-MOS transistor QP2 of the upper half bridge and the first active switch transistor of the lower half bridge form a second bridge arm.

5. According to claim 3, the mining piezoelectric vibration energy synchronous extraction circuit is characterized in that: The lower half bridge of the active rectification current circuit module includes a first N-MOS tube QN1, a second N-MOS tube QN2, a first comparator CMP1, and a second comparator CMP2; The positive input terminal of the first comparator CMP1 is connected to the source of the first N-MOS transistor QN1, the negative input terminal of the first comparator CMP1 is connected to the drain of the first N-MOS transistor QN1, and the output terminal of the first comparator CMP1 is connected to the gate of the first N-MOS transistor QN1; The positive input terminal of the second comparator CMP2 is connected to the source of the second N-MOS transistor QN2, the negative input terminal of the second comparator CMP2 is connected to the drain of the second N-MOS transistor QN2, and the output terminal of the second comparator CMP2 is connected to the gate of the second N-MOS transistor QN2; The drain of the first N-MOS tube QN1 is connected to the drain of the first P-MOS tube QP1, and the drain of the second N-MOS tube QN2 is connected to the drain of the second P-MOS tube QP2; the source of the first N-MOS tube QN1 and the source of the second N-MOS tube QN2 are both connected to the other output end (N) of the piezoelectric module and the positive voltage end of the energy storage capacitor.

6. The mining piezoelectric vibration energy synchronous extraction circuit according to claim 3, 4 or 5, characterized in that: The input end of the current zero-crossing detection circuit module is connected to the gate of the first N-MOS transistor QN1 and the gate of the second N-MOS transistor QN2, and the output end of the current zero-crossing detection circuit module is connected to the control end of the synchronous switch module; When the gate of the first N-MOS transistor QN1 and the gate of the second N-MOS transistor QN2 are both at low level, it is determined that the current source current ip(t) in the piezoelectric module passes through zero, and the synchronous switch circuit is controlled to be turned on.

7. The mining piezoelectric vibration energy synchronous extraction circuit according to claim 6 is characterized in that: The current zero-crossing detection circuit module includes a first NOR gate NOR1, a second NOR gate NOR2, a first NOT gate NOT1, a second NOT gate NOT2, a third NOT gate NOT3, a fourth NOT gate NOT4, a first RC filter circuit and a second RC filter circuit; The gate of the first N-MOS transistor QN1 and the gate of the second N-MOS transistor QN2 are respectively connected to the two input ends of the first NOR gate NOR1, the input end of the first NOR gate NOR1 is connected to the input end of the first NOT gate NOT1, the output end of the first NOT gate NOT1 is respectively connected to the input end of the second NOT gate NOT2 and one input end of the second NOR gate NOR2 after passing through the first RC filtering circuit, the output end of the second NOT gate NOT2 is connected to the input end of the third NOT gate NOT3 after passing through the second RC filtering circuit, the output end of the third NOT gate NOT3 is connected to the other input end of the second NOR gate NOR2, the output end of the second NOR gate NOR2 is connected to the input end of the fourth NOT gate NOT4, and the output end of the fourth NOT gate NOT4 is connected to the control end connected to the synchronous switch module.

8. The mining piezoelectric vibration energy synchronous extraction circuit according to claim 7 is characterized in that: The synchronous switch circuit is composed of two P-MOS switch tubes connected in series, the circuit is connected across the piezoelectric element and the rectifier circuit, and the output end of the fourth NOT gate NOT4 of the current zero-crossing detection circuit module is connected to the gates of the two P-MOS switch tubes connected in series; When it is determined that the current ip(t) passes through the zero point, the current zero-crossing detection circuit module outputs a low level, controls the switch tube to be turned on, and the piezoelectric capacitor discharges to the ground.

9. A method for synchronous extraction of piezoelectric vibration energy for mining based on the energy synchronous extraction circuit according to any one of claims 1 to 8, characterized in that: The extraction method comprises: S1: The amplitude of the piezoelectric module current source ip(t) gradually increases from zero, and 0<V AB <|V th |, the current zero-crossing detection circuit module outputs a low-level signal to control the synchronous switch module to turn on, and the piezoelectric capacitor in the piezoelectric module discharges; where V AB is the voltage difference between the upper and lower half bridge junctions of the active rectifier current circuit module, which is equal to the voltage value across the piezoelectric module, V th is the threshold voltage of the first bridge arm and the second bridge arm of the active rectifier circuit module; S2: The amplitude of the current source ip(t) continues to increase. When V AB ≥|V th |, the current zero-crossing detection circuit module outputs a high-level signal to control the synchronous switch module to be cut off, and the piezoelectric module charges the energy storage capacitor through the active rectifier circuit module; S3: The amplitude of the current source ip(t) gradually decreases from zero, V AB <0 and |V AB |<|V th |, the charging stops, and the current zero-crossing detection circuit module outputs a low-level signal to control the synchronous switch module to turn on, and the piezoelectric capacitor in the piezoelectric module discharges; S4: The amplitude of the current source ip(t) continues to decrease. When |V AB |≥|V th |, the current zero-crossing detection circuit module outputs a high-level signal to control the synchronous switch module to be cut off, and the piezoelectric module charges the energy storage capacitor through the active rectifier circuit module.

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