A vibrating wire sensor excitation control circuit, method and apparatus

Abstract

The application relates to a vibrating string sensor excitation control circuit, method and device, the control circuit comprising a control subcircuit, a voltage regulating circuit, a driving circuit and a power supply circuit, the control subcircuit being connected with the voltage regulating circuit and the driving circuit respectively, the voltage regulating circuit being connected with the driving circuit, the power supply circuit being used for providing power supply for the excitation control circuit, the voltage regulating circuit being used for providing positive and negative power supply voltages with adjustable voltage amplitudes according to a second control signal of the control subcircuit, the driving circuit being used for outputting an excitation signal with positive and negative voltage pulses according to a third control signal of the control subcircuit, generating opposite direction currents at different moments on a coil, generating an alternating magnetic field around the coil, forming a pushing force and a pulling force on a soft iron sheet in the magnetic field, accelerating the vibration of the vibrating string and saving energy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of geotechnical engineering monitoring, in particular to a vibrating string sensor excitation control circuit, method and device. BACKGROUND

[0002] At present, in the safety monitoring of geotechnical engineering, safety monitoring instruments such as vibrating string (or steel string) instruments are usually used to monitor physical quantities such as stress and strain, temperature, joint opening, leakage and deformation of geotechnical engineering, so as to analyze and judge the safety of geotechnical engineering.

[0003] The vibrating string instrument, or vibrating string sensor, includes a homogeneous steel string fixed at both ends. The length of the steel string is L, and when sensing external force F, the external force F includes stress and strain, temperature, joint opening, leakage and deformation of geotechnical engineering. The steel string will produce a tensile deformation of ΔL, and the influence of temperature T is considered within the elastic range:

[0004]

[0005] In the formula, a represents the linear expansion coefficient, L represents the vibrating string length, ΔL represents the tensile deformation of the vibrating string under the action of force F, ΔT = T - T0 represents the temperature change, T represents the temperature, and T0 represents the initial temperature.

[0006] The mechanical vibration natural frequency f of the vibrating string is calculated as follows:

[0007]

[0008] In the formula, E represents the elastic modulus of the vibrating string, p V represents the density of the vibrating string, and λ represents the Poisson's ratio of the vibrating string material. E, p V and λ are all constant.

[0009] The formulas (1) and (2) are arranged to eliminate the common variable, and F is obtained as a determined function of f and T. By measuring f and T, the measurement of external force F can be realized. It can be seen that the vibration natural frequency parameter f of the vibrating string is the most critical measurement factor.

[0010] The natural frequency is measured by excitation and vibration pickup. The high-voltage plucking excitation mode uses 100-200V high voltage to send a single pulse signal to the sensor coil to make the vibrating string vibrate. The high voltage will cause fatigue and aging of the sensing element, and higher requirements are put forward for the insulation performance of the sensor. Long-term use will cause the sensor accuracy to deteriorate or even fail. In addition, the high voltage generated during excitation also threatens the personal safety of the user.

[0011] The excitation waveform of the low-voltage sweep excitation mode is generated by a digital system, is a series of square waves with a fixed amplitude (5V or 3.3V) and adjustable frequency, the square wave width linearly changes with the frequency, the low-voltage sweep excitation mode has a long duration of each excitation, which leads to a prolonged sensor measurement time, a temperature rise of the vibrating string, an influence on the measurement accuracy of the instrument, and difficulty in realizing fast measurement of the sensor, and an increase in power consumption.

[0012] Therefore, how to quickly start the vibrating string is a problem to be solved at present. SUMMARY

[0013] The purpose of the present application is to provide a vibrating string sensor excitation control circuit, method and device, which adopts positive and negative power supply voltages, forms currents with opposite directions on the coil at different times, thereby generating an alternating magnetic field around the coil, forming a thrust and a pull on the soft iron sheet in the magnetic field, accelerating the start of the vibrating string, and saving energy.

[0014] In the first aspect, the above invention purpose of the present application is realized by the following technical scheme:

[0015] A vibrating string sensor excitation control circuit, comprising a control sub-circuit, a voltage regulation circuit, a driving circuit and a power supply circuit, the control sub-circuit is connected with the voltage regulation circuit and the driving circuit respectively, the voltage regulation circuit is connected with the driving circuit, the power supply circuit is used for providing power supply for the excitation control circuit, the voltage regulation circuit is used for providing positive and negative power supply voltages with adjustable voltage amplitude according to the second control signal of the control sub-circuit, the driving circuit is used for outputting an excitation signal with positive and negative voltage pulses according to the third control signal of the control sub-circuit, for generating currents with different directions on the coil.

[0016] The present application is further provided that: the control sub-circuit comprises a control chip, the power supply circuit comprises a boost circuit, a voltage stabilizing circuit and a first negative power supply circuit connected in sequence, the boost circuit is used for increasing the energy storage battery voltage to a boost voltage, the voltage stabilizing circuit is used for stabilizing the boost voltage to obtain a first voltage and a second voltage, and the first negative power supply circuit is used for converting the second voltage into a first negative power supply voltage, the voltage amplitude value of the first negative power supply voltage is the same as that of the second voltage.

[0017] The present application is further provided that: the voltage stabilizing circuit comprises a first voltage stabilizing circuit and a second voltage stabilizing circuit, the enable end of the first voltage stabilizing circuit is connected with a switch, when the switch is closed, the first voltage stabilizing circuit works to generate the first voltage for providing power supply for the control sub-circuit, and the enable end of the second voltage stabilizing circuit is connected with the control signal output end of the control sub-circuit, when the enable signal is effective, the boost voltage is converted into the second voltage.

[0018] The application further provides that the voltage regulating circuit comprises a first isolation circuit, a selection circuit, an adjustable circuit and a second negative power supply circuit connected in sequence, the input of the first isolation circuit is connected to the control sub-circuit, the adjustable circuit selects different resistance networks according to the second control signal output by the control sub-circuit, and outputs different power supply voltages, and the second negative power supply circuit converts the adjustable voltage into a second negative voltage power supply.

[0019] The application further provides that the selection circuit comprises a multiple-to-one switch chip for selecting the resistance networks, and the adjustable circuit comprises an adjustable chip, the voltage input end of which is connected to the power supply output end of the boost circuit, and the adjustable chip converts the boost voltage into an adjustable voltage when the enable signal output by the control sub-circuit is effective.

[0020] The application further provides that the drive circuit comprises a second isolation circuit, a switch control circuit and a drive sub-circuit connected in sequence, and the input of the second isolation circuit is connected to the output of the control sub-circuit.

[0021] The application further provides that the drive circuit comprises a second isolation circuit, a switch control circuit and a drive sub-circuit connected in sequence, and the drive circuit is used for outputting corresponding drive signals according to the third control signal group output by the control sub-circuit, and combining the adjustable positive and negative power supply output by the voltage regulating circuit to be applied to both ends of the coil, so as to change the current direction on the coil.

[0022] The application further provides that the drive sub-circuit comprises an H-bridge drive chip.

[0023] In the second aspect, the above application purpose is achieved by the following technical scheme.

[0024] A vibrating string sensor excitation method, an excitation signal is applied to the excitation coil, the excitation signal comprises a positive pulse of a positive voltage amplitude and a negative pulse of a negative voltage amplitude, which is used for generating opposite direction currents on the coil to form positive excitation and negative excitation, generating an alternating magnetic field around the coil, forming a pushing force on the soft iron sheet in the alternating magnetic field in the positive excitation, forming a pulling force on the soft iron sheet in the alternating magnetic field in the negative excitation, and making the vibrating string quickly vibrate under the action of the pushing force and the pulling force.

[0025] In the third aspect, the above application purpose is achieved by the following technical scheme.

[0026] The application discloses a vibrating string sensor exciting device, which comprises an exciting control circuit, a coil, a vibrating string and a soft iron sheet, the soft iron sheet is arranged on the vibrating string, the coil is arranged on one side of the vibrating string, the exciting control circuit outputs an exciting signal, the coil generates opposite currents under the action of the exciting signal, forms positive and negative excitations, generates an alternating magnetic field around the coil, forms a pushing force on the soft iron sheet in the alternating magnetic field in the positive excitation, forms a pulling force on the soft iron sheet in the alternating magnetic field in the negative excitation, and the vibrating string is rapidly excited under the action of the pushing force and the pulling force.

[0027] Compared with the prior art, the application has the beneficial technical effects that:

[0028] 1. The exciting control circuit of the application outputs positive and negative pulse signals with adjustable voltage by controlling the positive and negative voltages and driving signals of the driving circuit, generates currents in two directions on the coil, forms a magnetic field to generate a pushing force and a pulling force on the vibrating string, and accelerates the vibrating string to be excited;

[0029] 2. Further, the application isolates the control chip from the vibrating string analog signal by arranging the isolation circuit, and enhances the anti-interference ability of the circuit;

[0030] 3. Further, the application simultaneously generates negative power supply voltages with the same amplitude by arranging the voltage adjustable power supply, generates the exciting signals with positive and negative voltages, and realizes the alternating control of the magnetic field. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a structure schematic diagram of the exciting control circuit of one specific embodiment of the application;

[0032] Figure 2 is a structure schematic diagram of the power supply circuit of one specific embodiment of the application;

[0033] Figure 3 is a structure schematic diagram of the voltage regulating circuit of one specific embodiment of the application;

[0034] Figure 4 is a structure schematic diagram of the driving circuit of one specific embodiment of the application;

[0035] Figure 5 is a structure schematic diagram of the control sub-circuit of one specific embodiment of the application;

[0036] Figure 6 is a structure schematic diagram of the voltage regulating circuit of one specific embodiment of the application;

[0037] Figure 7 is a structure schematic diagram of the first voltage stabilizing circuit of one specific embodiment of the application;

[0038] Figure 8is a second voltage stabilizing circuit structure diagram of one embodiment of the present application;

[0039] Figure 9 is a first negative power supply voltage circuit structure diagram of one embodiment of the present application;

[0040] Figure 10 is a first isolation circuit structure diagram of one embodiment of the present application;

[0041] Figure 11 is a selection circuit structure diagram of one embodiment of the present application;

[0042] Figure 12 is an adjustable circuit structure diagram of one embodiment of the present application;

[0043] Figure 13 is a switch control circuit structure diagram of one embodiment of the present application. DETAILED DESCRIPTION

[0044] The present application is further described in detail below with reference to the accompanying drawings. Embodiment One

[0046] A vibrating string sensor excitation control circuit of the present application, as shown in the figure, includes a control sub-circuit, a voltage regulating circuit, a driving circuit, and a power supply circuit. The control sub-circuit is connected to the voltage regulating circuit and the driving circuit. The voltage regulating circuit is connected to the driving circuit. The power supply circuit is used to provide power to the excitation control circuit. The voltage regulating circuit is used to provide an adjustable voltage power supply according to the control signal of the control sub-circuit. The driving circuit is used to apply excitation to the coil according to the driving signal given by the control sub-circuit in combination with the adjustable voltage power supply output. Figure 1

[0047] The control sub-circuit includes a control chip that generates control signals to the power supply circuit, the voltage regulating circuit, and the driving circuit. The power supply circuit controls the output of the power supply according to the first control signal group given by the control sub-circuit. The voltage regulating circuit adjusts the output voltage value according to the second control signal group given by the control sub-circuit and converts the output voltage to positive and negative power supply voltages, which are output to the driving circuit. The driving circuit outputs a driving signal to the ends of the coil according to the third control signal group given by the control sub-circuit in combination with the positive and negative power supply voltages, changes the direction of the current flowing through the coil, and generates an alternating magnetic field around the coil to produce a pushing force and a pulling force on the soft iron piece in the magnetic field, accelerate the movement of the soft iron piece, and drive the vibrating string connected to the soft iron piece to vibrate.

[0048] The power supply circuit is used to convert the battery voltage of the energy storage battery into the first voltage required by the control sub-circuit, the second voltage required by the voltage regulating circuit, and the first negative power supply voltage required by the driving circuit. ​

[0049] As shown in Figure 2 The power supply circuit includes a boost circuit, a voltage stabilizing circuit and a first negative power supply circuit connected in sequence, the boost circuit is used to increase the battery voltage of the energy storage battery to a boost voltage, the voltage stabilizing circuit is used to stabilize and step down the boost voltage to obtain a first voltage and a second voltage, and the first negative power supply circuit is used to convert the second voltage into a first negative power supply voltage, the voltage amplitude value of the first negative power supply voltage is the same as that of the second voltage, and the second voltage and the first negative power supply voltage are used to supply power to the excitation control circuit.

[0050] The voltage regulating circuit is used to adjust the voltage amplitude value according to the second control signal group output by the control sub-circuit, convert the second voltage into a positive power supply voltage with an adjustable voltage amplitude value, and then generate a negative power supply voltage with the same voltage amplitude value according to the adjustable positive power supply. The driving circuit applies the positive power supply voltage and the negative power supply voltage to the two ends of the coil in time according to the driving signal output by the control sub-circuit, so that the current direction flowing through the coil is converted between the positive direction and the reverse direction, and the positive excitation and the negative excitation are formed on the coil. The change of the current direction on the coil generates an alternating magnetic field around the coil. When the alternating magnetic field is in the positive excitation, a string pushing force is generated on the soft iron sheet on the vibrating string in the alternating magnetic field, and when the alternating magnetic field is in the negative excitation, a string pulling force is generated on the soft iron sheet on the vibrating string in the alternating magnetic field. Here, the string pushing force and the string pulling force are relative, that is, the directions of the two forces are opposite.

[0051] One excitation process is set as a combination of positive excitation and negative excitation, and the positive excitation and the negative excitation are applied to the coil with a mutual interval. The magnetic force applied to the soft iron sheet on the vibrating string is a process of interaction between the string pushing force and the string pulling force. Under the interaction between the string pushing force and the string pulling force, the vibrating process of the vibrating string is accelerated, and the excitation efficiency is improved.

[0052] As shown in Figure 3 The voltage regulating circuit includes a first isolation circuit, a selection circuit, an adjustable circuit and a second negative power supply circuit connected in sequence. The input of the first isolation circuit is connected to the control sub-circuit, and the input of the selection circuit is connected to the output of the first isolation circuit. According to the first isolation control signal output by the first isolation circuit, different resistance networks are selected.

[0053] Under the action of the second control signal group output by the control sub-circuit, the adjustable circuit adjusts the output voltage according to the value of the resistance network. Different resistance networks correspond to different output voltages, so as to realize the adjustment of the power supply voltage.

[0054] The second negative power supply circuit is connected to the output of the adjustable circuit, and converts the adjustable voltage into a second negative voltage. The voltage amplitude value of the second negative voltage is the same as that of the adjustable voltage, and the positive and negative power supplies with adjustable voltage amplitude values are generated.

[0055] The adjustable voltage positive and negative power supply with different amplitudes is applied to the coil, so that the magnetic induction intensity of the alternating magnetic field changes to adapt to different sensors and coils.

[0056] According to the inherent frequency of the sensor, the duration of the positive power supply voltage and the negative power supply voltage applied to the coil is determined, and the duration of the positive power supply voltage applied to the coil is the same as the duration of the negative power supply voltage applied to the coil, at this time, a specific positive and negative power supply pulse signal is applied to the coil.

[0057] When the inherent frequency of the sensor is between 2000-3000Hz, the duration of a specific positive and negative power supply pulse signal is between 167-250us.

[0058] The driving circuit is used to output the excitation signal applied to the coil according to the third control signal group output by the control sub-circuit and the positive and negative power supply voltage, and the positive pulse or negative pulse duration of the excitation signal is determined by the third control signal group, and the amplitude of the positive pulse and the negative pulse is determined by the positive and negative power supply voltage.

[0059] As shown in Figure 4 , the driving circuit includes a second isolation circuit, a switch control circuit and a driving sub-circuit connected in sequence, the input of the second isolation circuit is connected to the output of the control sub-circuit, the input of the switch control circuit is connected to the output of the second isolation circuit, and the output of the switch control circuit is connected to the input of the driving sub-circuit, the driving circuit is used to output the corresponding driving signal according to the third control signal group output by the control sub-circuit, and the adjustable positive and negative power supply output by the voltage regulation circuit is applied to both ends of the coil to realize the change of the current direction on the coil.

[0060] In a specific embodiment of the present application, the first control signal group includes at least one sub-control signal, the second control signal group includes at least one sub-control signal, and the third control signal group includes at least one sub-control signal. Specific embodiment two

[0062] A vibrating string sensor excitation control circuit is provided, which includes a control sub-circuit, a voltage regulation circuit, a driving circuit and a power supply circuit, as shown in Figure 5 , the control sub-circuit includes a control chip U1, the control chip U1 outputs a first control signal group to the power supply circuit, a second control signal group to the voltage regulation circuit, and a third control signal group to the driving circuit.

[0063] In a specific embodiment of the present application, the first control signal group includes two enable signals A_EN and A5_EN, the first enable signal A_EN is used for enabling control of the boost circuit, and the second enable signal A5_EN is used for enabling control of the voltage stabilizing circuit.

[0064] The second control signal group includes an enable signal MVCC_EN, two selection control signals, a third enable signal MVCC_EN for enabling control of the adjustable circuit, and a combination of a first selection control signal POWER_SELA and a second selection control signal POWER_SELB for selection control of the resistance network.

[0065] The third control signal group includes two switch control signals, a first switch control signal VW_SCAN1_1 and a second switch control signal VW_SCAN2_1, for controlling the operation of the driving circuit.

[0066] The power supply circuit includes a boost circuit, a voltage stabilizing circuit, and a first negative power supply circuit. Figure 6 As shown in the figure, the boost chip U2 and its peripheral circuit are included, the input voltage VIN of the boost chip U2 is the energy storage battery voltage BAT+, and after passing through the boost chip U2, an output voltage VOUT of 5.5V is obtained.

[0067] The enable end EN of the boost chip U2 is connected with the enable end A_EN of the control chip U1, when the enable signal EN is valid, the boost chip U2 starts and outputs a voltage of 5.5V.

[0068] An inductor L1 is arranged between the input end VIN of the boost chip U2 and the feedback SW end, for boosting.

[0069] A sampling resistance string is arranged between the output end VOUT of the boost chip U2 and the ground, the sampling resistance string is a series combination of a resistance R27 and a resistance R25, one end of the resistance R27 is connected with the output end VOUT, the series connection point of the resistance R27 and the resistance R25 is connected to the sampling end FB of the boost chip U2, and the other end of the resistance R25 is grounded.

[0070] The size of the output voltage VOUT is related to the sizes of the resistance R27 and the resistance R25, and the calculation formula is as follows: VOUT = ((R27 / R25)+1)*K1 (1);

[0071] In the formula, K1 is a coefficient, and the value is 0.795.

[0072] A parallelly connected filter capacitor C30 and a filter capacitor C31 are arranged between the power supply positive of the energy storage battery and the ground.

[0073] A parallelly connected filter capacitor C28 and a filter capacitor C29 are arranged between the output end VOUT of the boost chip U2 and the ground, the output end VOUT is led out to a 5.5V power supply output through a magnetic bead R28, and a filter capacitor C27 is arranged at the 5.5V power supply output end. The magnetic bead R28 is used for high-frequency filtering of the power supply.

[0074] The voltage stabilizing circuit includes a first voltage stabilizing circuit and a second voltage stabilizing circuit. Figure 7 As shown, the first voltage stabilizing circuit includes a voltage stabilizing chip U3 and its peripheral circuits. The enable terminal EN of the voltage stabilizing chip U3 is connected to the switch and is started by the switch. When the switch is closed, the voltage stabilizing chip U3 works to stabilize the power supply voltage BAT+ of the energy storage battery at the power supply voltage 3.3V required by the control chip U1.

[0075] like Figure 8 As shown, the second voltage stabilizing circuit includes a voltage stabilizing chip U4 and its peripheral circuits. The enable terminal EN of the voltage stabilizing chip U4 is connected to the second enable signal A5_EN output terminal of the control chip U1, and its input voltage terminal is connected to the voltage output terminal of the boost circuit, which is used to convert the boost voltage generated by the boost circuit into a second voltage.

[0076] like Figure 9 As shown, the first negative power supply voltage circuit includes a power supply chip U5, which is an adjustable charge pump voltage converter for converting a positive power supply voltage into a negative power supply voltage.

[0077] After the switch is closed, voltage regulator chip U3 operates, powering control chip U1. The control chip then outputs a first enable signal A_EN, which controls boost chip U2 to operate. It then outputs a second enable signal A5_EN, which controls voltage regulator chip U4 to operate. This ensures that the power circuit begins operating after the switch is closed, and the entire circuit is disconnected when the switch is opened, saving energy.

[0078] The voltage regulating circuit includes a first isolation circuit, a selection circuit, an adjustable circuit and a second negative power supply circuit which are connected in sequence.

[0079] like Figure 10 As shown, the first isolation circuit includes two paths. The first isolation circuit includes an optoelectronic isolation chip U6. The input end of the input side of the optoelectronic isolation chip U6 is connected to the first power supply voltage through a resistor R26, and the output end of the input side is connected to the first selection control signal POWER_SELA output end of the control chip U1. The input end of its output side is connected to the second power supply voltage through a resistor R23, and outputs the first isolation control signal SELA to the selection circuit as an output end, and its output end is grounded.

[0080] When the first selection control signal POWER_SELA is low, the optoelectronic isolation chip U6 is turned on and the first isolation control signal SELA is low. When the first selection control signal POWER_SELA is high, the optoelectronic isolation chip U6 is turned off and the first isolation control signal SELA is high.

[0081] The structure of the second isolation circuit is the same as that of the first isolation circuit, and will not be described in detail.

[0082] The second isolation circuit outputs a second isolation control signal SELB. Similarly, when the second selection control signal POWER_SELB is low, the optoelectronic isolation chip U7 is turned on, and the second isolation control signal SELB is low.

[0083] The selection circuit is used to select different resistance networks, and the output voltage of the power supply is adjusted after matching the resistance of the adjustable circuit.

[0084] As shown in Figure 11 The selection circuit includes a multi-selection switch chip U8. The channel CH4 is connected to ground through a resistor R33, the channel CH5 is connected to ground through a resistor R35, the channel CH6 is connected to ground through a resistor R38, and the channel CH7 is connected to ground through a resistor R39. In this embodiment, the multi-selection switch chip U8 is powered by the second voltage and the first negative power supply voltage.

[0085] When the values of the input terminals SELA and SELB of the switch chip U8 are different, one of the channels CH4-CH7 is connected to the output terminal COM, and the output terminal COM is connected to the MVCC_RES terminal of the adjustable circuit.

[0086] As shown in Figure 12 The adjustable circuit includes an adjustable chip U9 and its peripheral circuit. The input terminal of the adjustable chip U9 is connected to the power output terminal of the boost circuit. The enable terminal EN is connected to the third enable signal MVCC_EN output terminal of the control chip U1 through a resistor R34 and grounded through R32. The output terminal OUT outputs the adjustable voltage M+VCC. The sampling terminal FB is connected to one end of a resistor R37, the output terminal COM of the switch chip U8, and one end of a capacitor C37. The other end of the one end of the resistor R37 and the other end of the capacitor C37 are connected to the adjustable voltage M+VCC output terminal OUT.

[0087] When the output current is greater than the set value, the adjustable voltage of the output terminal OUT of the adjustable chip is related to the resistance connected to the output terminal COM of the switch chip U8.

[0088] When the output terminal COM of the switch chip U8 is connected to the channel CH4, the adjustable voltage M+VCC of the output terminal OUT of the adjustable chip is calculated as follows:

[0089] M+VCC = VREF((R37 / R33)+1) (2);

[0090] By setting different VREF, different adjustable voltages M+VCC are obtained.

[0091] The structure of the second negative power supply circuit is the same as that of the first negative power supply circuit, and the positive voltage of the adjustable voltage is converted into a negative voltage M-VCC with the same amplitude.

[0092] The driving circuit comprises a second isolation circuit, a switch control circuit and a driving sub-circuit connected in sequence. The second isolation circuit has the same structure as the first isolation circuit, and is used for converting the first switch control signal VW_SCAN1_1 output by the control chip into a first switch isolation signal VW_SCAN1 and converting the second switch control signal VW_SCAN2_1 into a second switch isolation signal VW_SCAN2, and transmitting to the switch control circuit.

[0093] As shown in Figure 13 The switch control circuit comprises PNP type triodes Q2 and Q3. The PNP type triode Q2 is arranged as a typical switch circuit, the emitter thereof is connected to the second power supply voltage end through a resistor R57, the collector thereof is connected to the first input end of the driving sub-circuit, and the base thereof is connected to the first switch isolation signal VW_SCAN1 output end.

[0094] The PNP type triode Q3 is also arranged as a typical switch circuit, the emitter thereof is connected to the second power supply voltage end through a resistor R66, the collector thereof is connected to the second input end of the driving sub-circuit, and the base thereof is connected to the second switch isolation signal VW_SCAN2 output end.

[0095] The driving sub-circuit comprises an H-bridge driving chip U11, the positive power supply of which is connected to the adjustable voltage M+VCC output end, the ground of which is connected to the negative power supply voltage M-VCC output end, the first output end of which is connected to the sensor first end VW1 through a resistor R65, and the second output end of which is connected to the sensor second end VW2 through a resistor R67.

[0096] When the first switch isolation signal VW_SCAN1 is at a low level, the PNP type triode Q2 is turned on, and the first input end of the driving sub-circuit is at a high level. Conversely, when the first switch isolation signal VW_SCAN1 is at a high level, the PNP type triode Q2 is turned off, and the first input end of the driving sub-circuit is at a low level.

[0097] The input of the second input end of the driving sub-circuit is the same as the input of the first input end, and will not be described again.

[0098] The driving chip U11 outputs the VW1 and VW2 signals according to the input of the first input end and the second input end, and applies the signals to the two ends of the sensor coil, respectively.

[0099] When the first input end of the driving chip U11 inputs a high level and the second input end inputs a low level, the VW1 is at a high level and the VW2 is at a low level, and the current direction on the sensor coil is a positive direction.

[0100] When the first input end of the driving chip U11 inputs a low level and the second input end inputs a high level, the VW1 is at a low level and the VW2 is at a high level, and the current direction on the sensor coil is a reverse direction.

[0101] By changing the direction of the current on the coil, the direction of the magnetic field around the coil is changed, and different forces are generated on the soft iron sheet in the magnetic field, so that the soft iron sheet drives the vibrating string to vibrate.

[0102] Due to differences in manufacturing processes and the like, some sensors are not easy to vibrate, and by changing the voltage amplitude of the high level and the low level, different coils and vibrating strings are adapted to make the vibrating string vibrate and improve the vibration speed of the sensor. Specific embodiment three

[0104] The application discloses a vibrating string type sensor excitation device, which comprises an excitation control circuit, a coil, a vibrating string and a soft iron sheet.

[0105] A excitation signal includes a positive pulse formed by a positive power supply voltage and a negative pulse formed by a negative power supply voltage, and the period of the excitation signal is related to parameters such as the inherent frequency of the vibrating string. At least one excitation signal is applied to the coil, a transient process is generated on the vibrating string, and after the transient process lasts for a period of time, the vibrating string enters a stable free vibration state and generates a stable free vibration waveform. By detecting the free vibration waveform, the vibration frequency is obtained, and the external force F is calculated from the vibration frequency.

[0106] The application discloses a vibrating string type sensor excitation device, which comprises an excitation control circuit, a coil, a vibrating string and a soft iron sheet.

[0107] The test results of the device using the first type of vibrating string sensor show that the vibrating string can be reliably excited by using 3-5 excitation signals. When using 3 excitation signals, the peak-to-peak value of the excitation signal is ± 5V, the frequency range of the excitation signal is 2800-3000Hz, the period range of the excitation signal is 178-167us, the excitation frequency points are set at 2800Hz, 2900Hz and 3000Hz, and the corresponding excitation signal periods are 178us, 172us and 167us. The duration of the 3 excitation signals is 1.15ms. After the excitation signal stops, the transient process lasts for about 7.3ms, and a stable free vibration waveform is generated. The duration of the free vibration waveform of the vibrating string after excitation is 494.1ms, which fully meets the sample collection time of the frequency measurement circuit and the frequency measurement value is stable, with an error of less than ± 0.1Hz.

[0108] When the second type of vibrating string sensor is used, the frequency of the excitation signal is changed to 600Hz, 750Hz and 900Hz, the duration of the 3 excitation signals is about 4.1ms, and after the excitation signal stops, the transient process of the signal on the vibrating string lasts for about 8.6ms, and a stable free vibration waveform is generated. The duration of the free vibration waveform of the vibrating string is more than 880ms, which fully meets the sample collection time of the frequency measurement circuit and the frequency measurement value is stable, with an error of less than ± 0.1Hz.

[0109] The excitation mode of the vibrating string and the pulling string of the present application includes an excitation stage, a transient process stage and a free vibration stage. The excitation stage is the time period during which the excitation signal is applied, and the number of excitation signals at this time is controllable, which reduces the duration of the vibrating string excitation, greatly reduces the temperature rise effect of the vibrating string, and further reduces the temperature additional error of the vibrating string instrument, thereby improving the measurement accuracy of the instrument. The transient process stage is the transition process before the free vibration of the vibrating string after the excitation signal stops. In the free vibration stage, the vibrating string generates free vibration, and the frequency measurement is performed in this stage.

[0110] The above are preferred embodiments of the present application, but do not limit the protection scope of the present application, therefore: any equivalent changes made in the structure, shape and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A vibrating wire sensor excitation control circuit, characterized by: The control sub-circuit, the voltage regulation circuit, the driving circuit and the power supply circuit are connected with each other, the control sub-circuit is connected with the voltage regulation circuit and the driving circuit, the power supply circuit is used for providing power supply for the vibration control circuit, the voltage regulation circuit is used for providing positive and negative power supply voltages with adjustable voltage amplitudes according to the second control signal of the control sub-circuit, the driving circuit is used for outputting excitation signals with positive and negative voltage pulses according to the third control signal of the control sub-circuit, and the excitation signals are used for generating currents with different directions on the coil, the voltage regulation circuit comprises a first isolation circuit, a selection circuit, an adjustable circuit and a second negative power supply circuit which are connected in sequence, the input of the first isolation circuit is connected to the control sub-circuit, the adjustable circuit selects different resistance networks according to the second control signal output by the control sub-circuit, and different power supply voltages are output correspondingly, the second negative power supply circuit converts the adjustable voltage into a second negative voltage power supply, the selection circuit comprises a multiple-to-one switch chip and is used for selecting the resistance networks, the adjustable circuit comprises an adjustable chip, a voltage input end of the adjustable chip is connected to the power output end of the boost circuit, and the boost voltage is converted into an adjustable voltage when the enable signal output by the control sub-circuit is effective, the driving circuit comprises a second isolation circuit, a switch control circuit and a driving sub-circuit which are connected in sequence, the driving circuit is used for outputting corresponding driving signals according to the third control signal group output by the control sub-circuit, and the driving signals are combined with the adjustable positive and negative power supply output by the voltage regulation circuit and applied to both ends of the coil, so that the direction of the current on the coil is changed, and the driving sub-circuit comprises an H-bridge driving chip.

2. The vibrating wire sensor excitation control circuit of claim 1, wherein: The control sub-circuit comprises a control chip, the power supply circuit comprises a boost circuit, a voltage stabilizing circuit and a first negative power supply circuit which are connected in sequence, the boost circuit is used for increasing the voltage of the energy storage battery to a boost voltage, the voltage stabilizing circuit is used for stabilizing the boost voltage to obtain a first voltage and a second voltage, and the first negative power supply circuit is used for converting the second voltage into a first negative power supply voltage, and the voltage amplitude value of the first negative power supply voltage is the same as that of the second voltage.

3. The vibrating wire sensor excitation control circuit of claim 1, wherein: The voltage stabilizing circuit comprises a first voltage stabilizing circuit and a second voltage stabilizing circuit, an enable end of the first voltage stabilizing circuit is connected with a switch, the first voltage stabilizing circuit works when the switch is closed to generate the first voltage and provide power supply for the control sub-circuit, and an enable end of the second voltage stabilizing circuit is connected with the control signal output end of the control sub-circuit, the second voltage stabilizing circuit converts the boost voltage into the second voltage when the enable signal is effective.

4. The vibrating wire sensor excitation control circuit of claim 1, wherein: The driving circuit comprises a second isolation circuit, a switch control circuit and a driving sub-circuit which are connected in sequence, and the input of the second isolation circuit is connected with the output of the control sub-circuit.

5. A vibrating string sensor excitation device, characterized by: The vibration control circuit, the coil, the vibrating string and the soft iron sheet are connected with each other, the vibration control circuit adopts the vibration control circuit of the vibrating string type sensor according to any one of claims 1 to 4, the soft iron sheet is arranged on the vibrating string, the coil is arranged on one side of the vibrating string, and the vibration control circuit is used for outputting excitation signals to the coil.

6. A method of exciting a vibrating string sensor, characterized by: The vibrating string sensor comprises the vibrating string sensor excitation device as claimed in claim 5, an excitation signal is applied to the excitation coil, the excitation signal comprises positive pulses of positive voltage amplitude and negative pulses of negative voltage amplitude, for generating opposite direction currents on the coil, forming positive excitation and negative excitation, generating an alternating magnetic field around the coil, forming a pushing force on the soft iron sheet located in the alternating magnetic field during positive excitation, forming a pulling force on the soft iron sheet located in the alternating magnetic field during negative excitation, so that the vibrating string is quickly excited under the action of the pushing force and the pulling force.

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