Displacement sensor calibration method and circuit and flywheel energy storage device

Abstract

The present invention discloses a calibration method and circuit of a displacement sensor and a flywheel energy storage device, and relates to the field of sensors. The displacement sensor is used to detect the rotor position of a magnetic bearing system. The calibration method includes: obtaining the current displacement detection value of the displacement sensor; determining the target displacement interval in which the current displacement detection value is in a target degree of freedom mapping relationship, wherein the target degree of freedom mapping relationship is the corresponding relationship between the displacement value of the target degree of freedom and time; and performing bias compensation on the displacement sensor according to the bias coefficient of the target displacement interval. The method can perform dynamic bias compensation on the displacement sensor according to the bias coefficient in different target displacement intervals, improve the measurement accuracy of the displacement sensor, and the stability of the magnetic bearing system, without manually adjusting the components in the circuit for bias compensation, reduce the complexity of operation, and avoid erroneous operation.

Description

Technical Field

[0001] The invention relates to the field of sensors, and in particular to a calibration method and circuit of a displacement sensor and a flywheel energy storage device. Background Art

[0002] In the related art, during the calibration and debugging process of the displacement sensor, two fixed excitation source signals are usually given externally. Generally, the fixed excitation source signals are the maximum positive displacement and the maximum negative displacement of the rotor of a certain degree of freedom. After the actual displacement signal received by the controller is compared with the theoretical displacement signal, the adjustable potentiometer in the displacement signal amplification circuit is manually adjusted to change the bias, or a fixed bias is automatically calculated by the controller. At this time, the bias in the displacement sensor is unique. Manually adjusting the adjustable potentiometer in the displacement signal amplification circuit to change the bias is complicated, time-consuming and labor-intensive. Manual operation is prone to other misoperations. In addition, the maximum movement stroke of the rotor in the displacement sensor is not actually a completely linear process due to the influence of other factors such as the air gap. The maximum movement stroke of the rotor is very small, about 0.25mm. Therefore, the sampling accuracy of the displacement sensor calculated by the unique bias method is not accurate enough. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one purpose of the present invention is to propose a displacement sensor calibration method, which can dynamically compensate the displacement sensor according to the bias coefficient in different target displacement intervals, improve the measurement accuracy of the displacement sensor, and the stability of the magnetic bearing system, without manually adjusting the components in the circuit for bias compensation, reduce the complexity of operation, and avoid erroneous operation.

[0004] A second objective of the present invention is to provide a calibration circuit for a displacement sensor.

[0005] The third object of the present invention is to provide a flywheel energy storage device.

[0006] In order to solve the above problems, an embodiment of the first aspect of the present invention provides a calibration method for a displacement sensor, wherein the displacement sensor is used to detect the rotor position of a magnetic bearing system, and the calibration method comprises: obtaining a current displacement detection value of the displacement sensor; determining a target displacement interval in which the current displacement detection value is in a target degree of freedom mapping relationship, wherein the target degree of freedom mapping relationship is a correspondence between the displacement value of the target degree of freedom and time; and performing bias compensation on the displacement sensor according to a bias coefficient of the target displacement interval.

[0007] According to the displacement sensor calibration method of the embodiment of the present invention, after the current displacement detection value of the displacement sensor is obtained, the target displacement interval is determined by the current displacement detection value, and the displacement sensor is dynamically biased compensated according to the bias coefficient in different target displacement intervals, thereby improving the measurement accuracy of the displacement sensor and the stability of the magnetic bearing system. There is no need to manually adjust the components in the circuit for bias compensation, which reduces the complexity of operation and avoids erroneous operations.

[0008] In some embodiments, the target degree of freedom mapping relationship is obtained according to the following steps: driving the rotor to operate with a displacement drive value so that the rotor moves from the maximum position in the negative direction of the target degree of freedom axis to the maximum position in the positive direction at a preset speed, and recording the displacement drive value and the displacement detection value of the displacement sensor at preset time intervals; the target degree of freedom mapping relationship includes a first correspondence between the displacement drive value and time and a second correspondence between the displacement detection value and time during the period when the rotor moves from the maximum position in the negative direction to the maximum position in the positive direction of the target degree of freedom axis.

[0009] In some embodiments, the displacement interval is the displacement difference between two adjacent displacement drive values; each of the displacement intervals has a corresponding bias coefficient, and the bias coefficient is the ratio of the difference between the first corresponding relationship and the second corresponding relationship corresponding to each of the displacement intervals.

[0010] In some embodiments, the excitation source signal sent to the displacement sensor is differentially processed to obtain the current midpoint voltage, wherein the excitation source signal is two same-frequency and opposite signals; the current displacement detection value is differentially processed to obtain a first differential signal; the first differential signal and the current midpoint voltage are differentially processed to obtain a second differential signal; the second differential signal is filtered, biased and amplified to obtain a new displacement detection signal; and the current displacement detection value is updated to the new displacement detection signal.

[0011] A second aspect of the present invention provides a calibration circuit for a displacement sensor, wherein the displacement sensor is used to detect the rotor position of a magnetic bearing system, and the calibration circuit comprises: a differential processing module, which is used to perform differential processing on a displacement detection value of the displacement sensor and an excitation source signal of the displacement sensor to obtain a differential signal; and a bias amplification processing module, which is used to perform bias amplification processing on the differential signal to obtain a displacement detection signal of the displacement sensor.

[0012] A controller is connected to the bias amplification processing module and the displacement sensor, and is used to obtain a current displacement detection value of the displacement sensor, determine that the current displacement detection value is in a target displacement interval of a target degree of freedom mapping relationship, and perform bias compensation on the displacement sensor according to a bias coefficient of the target displacement interval, wherein the target degree of freedom mapping relationship is a corresponding relationship between the displacement value of the target degree of freedom and time.

[0013] According to the calibration circuit of the displacement sensor of the embodiment of the present invention, after the controller obtains the current displacement detection value of the displacement sensor, it determines the target displacement interval, and dynamically compensates the displacement sensor according to the bias coefficient in different target displacement intervals, thereby improving the measurement accuracy of the displacement sensor and the stability of the magnetic bearing system. There is no need to manually adjust the components in the circuit for bias compensation, which reduces the complexity of operation and avoids erroneous operations.

[0014] In some embodiments, the differential processing module includes: a first operational amplifier circuit, the input end of the first operational amplifier circuit is the displacement detection value of the displacement sensor, and is used to perform differential processing on the displacement detection value to output a first differential signal; a second operational amplifier circuit, the input end of the second operational amplifier circuit is the excitation source signal, and is used to perform differential processing on the excitation source signal to obtain a current midpoint voltage, wherein the excitation source signal is two same-frequency and opposite signals; a third operational amplifier circuit, the input end of the third operational amplifier circuit is connected to the output end of the first operational amplifier circuit and the output end of the second operational amplifier circuit, and is used to perform differential processing on the first differential signal and the current midpoint voltage to obtain a second differential signal.

[0015] In some embodiments, the bias amplification processing module includes: a first resistor, a first end of the first resistor is connected to the output end of the third operational amplifier circuit and the first end of the inductor of the first digital potentiometer of the displacement sensor, a second end of the first resistor is connected to the adjustment end of the second digital potentiometer of the displacement sensor, the first resistor is used to adjust the bias of the inductor of the first digital potentiometer, and the first digital potentiometer and the second digital potentiometer are used to detect displacement signals of the same degree of freedom; a fourth operational amplifier circuit, a first input end of the fourth operational amplifier circuit is connected to the first end of the first resistor, the output end of the third operational amplifier circuit, and the first end of the inductor of the first digital potentiometer, the output end of the fourth operational amplifier circuit is connected to the second end of the inductor of the first digital potentiometer, and is used to amplify the second differential signal; a second resistor, a first end of the second resistor is connected to the output end of the fourth operational amplifier circuit, and a second end of the second resistor is connected to the A / D port of the controller, and is used to transmit the displacement detection signal.

[0016] In some embodiments, the calibration circuit further includes: a capacitor, a first end of the capacitor being connected to a first end of the inductor of the first digital potentiometer, and a second end of the capacitor being connected to a second end of the inductor of the first digital potentiometer and an adjustment end of the inductor of the first digital potentiometer.

[0017] In some embodiments, the controller is connected to the first digital potentiometer and the second digital potentiometer via SPI for sending the bias coefficient to the displacement sensor; the controller is also connected to the input end of the second operational amplifier circuit for sending the excitation source signal.

[0018] In some embodiments, the calibration circuit includes two differential processing modules and two bias amplification processing modules, wherein one differential processing module and one bias amplification processing module are connected to the first digital potentiometer and the second digital potentiometer for detecting the displacement signal of the first degree of freedom of the rotor, and another differential processing module and another bias amplification processing module are connected to the first digital potentiometer and the second digital potentiometer for detecting the displacement signal of the second degree of freedom of the rotor.

[0019] A third aspect of the present invention provides a flywheel energy storage device, comprising a flywheel, a magnetic bearing system, a displacement sensor and a calibration circuit of the displacement sensor described in the above embodiment.

[0020] According to the flywheel energy storage device of the embodiment of the present invention, the displacement sensor can be dynamically biased according to the bias coefficient in different target displacement intervals, thereby improving the measurement accuracy of the displacement sensor and the stability of the magnetic bearing system. There is no need to manually adjust the components in the circuit for bias compensation, which reduces the complexity of operation and avoids erroneous operations, thereby improving the accuracy and stability of the flywheel energy storage device and reducing energy consumption.

[0021] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0023] Figure 1 is a flow chart of a method for calibrating a displacement sensor according to an embodiment of the present invention;

[0024] Figure 2 is a schematic diagram of the corresponding relationship between the displacement value and the sampling time according to an embodiment of the present invention;

[0025] Figure 3is a schematic diagram of bias coefficients according to an embodiment of the present invention;

[0026] Figure 4 is a schematic diagram of a displacement sensor system according to an embodiment of the present invention;

[0027] Figure 5 is a schematic diagram of a calibration circuit of a displacement sensor according to an embodiment of the present invention;

[0028] Figure 6 is a structural block diagram of a flywheel energy storage device according to an embodiment of the present invention.

[0029] Reference numerals:

[0030] Flywheel energy storage device 200;

[0031] Displacement sensor 201; flywheel 202; magnetic bearing system 203; calibration circuit 100;

[0032] Differential processing module 110; bias amplification processing module 120; controller 130; first digital potentiometer 101;

[0033] A second digital potentiometer 102; a capacitor 103;

[0034] A first operational amplifier circuit 111 ; a second operational amplifier circuit 112 ; a third operational amplifier circuit 113 ; a first resistor 121 ; a fourth operational amplifier circuit 122 ; and a second resistor 123 . DETAILED DESCRIPTION

[0035] Embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. Embodiments of the present invention are described in detail below.

[0036] The first aspect of the present invention provides a method for calibrating a displacement sensor, which is used to detect the rotor position of a magnetic bearing system. The method for calibrating the displacement sensor can dynamically compensate for the offset of the displacement sensor according to the offset coefficient in different target displacement intervals, thereby improving the measurement accuracy of the displacement sensor and the stability of the magnetic bearing system. There is no need to manually adjust the components in the circuit for offset compensation, thereby reducing the complexity of operation and avoiding erroneous operations.

[0037] Reference below Figure 1 A method for calibrating a displacement sensor according to an embodiment of the first aspect of the present invention is described as follows: Figure 1 As shown, the method at least includes steps S1 to S3.

[0038] Step S1, obtaining the current displacement detection value of the displacement sensor.

[0039] Specifically, the magnetic bearing uses magnetic force to suspend the rotor in the air, so that there is no mechanical contact between the rotor and the stator; the principle is that the magnetic induction line is perpendicular to the magnetic levitation line, and the shaft core is parallel to the magnetic levitation line, so the weight of the rotor is fixed on the running track, and the shaft core is almost unloaded to support it in the direction opposite to the magnetic levitation line, so that the entire rotor is suspended in the air, on a fixed running track. There is no mechanical contact in the magnetic bearing, and the rotor can run at a very high speed. It has the advantages of low mechanical wear, low energy consumption, low noise, long life, no lubrication, and no oil pollution. It is particularly suitable for special environments such as high speed, vacuum, and ultra-clean. The role of the displacement sensor is to detect the rotor position of the magnetic bearing system. The timeliness and accuracy of its feedback signal are the key to the stability of the magnetic bearing control system.

[0040] If the rotor is disturbed, it will deviate from its initial position. When the rotor rotates in the magnetic field, it will cut the magnetic lines of force, thereby generating an induced electromotive force. After the rotor deviates from the initial position, the induced electromotive force generated at different positions is different. Therefore, the displacement sensor can obtain the current displacement detection value of the rotor.

[0041] Step S2, determining whether the current displacement detection value is within the target displacement interval of the target degree of freedom mapping relationship.

[0042] The target degree of freedom mapping relationship is the corresponding relationship between the displacement value of the target degree of freedom and time.

[0043] Specifically, in a plane, there are only three degrees of freedom, one is surface rotation, and the other two are up and down and left and right movement. In the present invention, the target degree of freedom is the maximum distance that the rotor moves up and down and left and right in the stator. There are multiple displacement intervals in the target degree of freedom. The target displacement interval can be understood as the interval in which the rotor moves in the stator at the current moment.

[0044] Step S3, performing bias compensation on the displacement sensor according to the bias coefficient of the target displacement interval.

[0045] Specifically, after determining the target displacement interval of the current rotor, the controller performs bias compensation on the displacement sensor according to the bias coefficient of the target displacement interval, thereby improving the accuracy of the displacement sensor, accurately obtaining the current position of the rotor, and improving the stability of the magnetic suspension bearing.

[0046] According to the displacement sensor calibration method of the embodiment of the present invention, after the current displacement detection value of the displacement sensor is obtained, the target displacement interval is determined by the current displacement detection value, and the displacement sensor is dynamically biased compensated according to the bias coefficient in different target displacement intervals, thereby improving the measurement accuracy of the displacement sensor and the stability of the magnetic bearing system. There is no need to manually adjust the components in the circuit for bias compensation, which reduces the complexity of operation and avoids erroneous operations.

[0047] In some embodiments, the target degree of freedom mapping relationship is obtained according to the following steps: driving the rotor to operate with a displacement drive value so that the rotor moves from the maximum position in the negative direction of the target degree of freedom axis to the maximum position in the positive direction at a preset speed, and recording the displacement drive value and the displacement detection value of the displacement sensor at preset time intervals; the target degree of freedom mapping relationship includes a first correspondence between the displacement drive value and time and a second correspondence between the displacement detection value and time during the period when the rotor moves from the maximum position in the negative direction to the maximum position in the positive direction of the target degree of freedom axis.

[0048] Specifically, the magnetic bearing is driven by the controller to make the rotor axis first reach the maximum position in the negative direction of the target freedom axis, that is, the minimum position of the displacement sensor range. Taking this as the starting point, the rotor axis begins to move toward the maximum position in the positive direction of the target freedom axis at a slow and constant speed. During the movement, it reaches the maximum position in the positive direction of the target freedom axis after a fixed time interval t, and takes this as the end point. The time used in the process is recorded as T, then T / t points are collected, and the displacement drive value and the displacement detection value of the displacement sensor are recorded at preset time intervals t. Due to various external factors, there is a difference between the displacement drive value and the detection value during the period when the controller controls the rotor from the maximum position in the negative direction to the maximum position in the positive direction of the target freedom axis. Therefore, the target freedom mapping relationship includes a first corresponding relationship between the displacement drive value and time and a second corresponding relationship between the displacement detection value and time. The first corresponding relationship can be understood as the corresponding relationship between the displacement drive value and time of the controller controlling the rotor movement, and the second corresponding relationship can be understood as the corresponding relationship between the actual displacement detection value and time of the rotor; such as Figure 2 As shown, taking the Y axis as an example, the magnetic bearing is driven by the controller to move the rotor axis from the maximum position in the negative direction of the Y axis to the maximum position in the positive direction of the Y axis. During the movement, the rotor position is recorded at a fixed time interval t. The first corresponding relationship between the displacement drive value and time is shown in Figure 2 As shown by the dashed line in the middle, the second corresponding relationship between the displacement detection value and time is as follows Figure 2 Shown by the solid line.

[0049] In some embodiments, the displacement interval is the displacement difference between two adjacent displacement driving values; each displacement interval has a corresponding bias coefficient, and the bias coefficient is the ratio of the difference between the first corresponding relationship and the second corresponding relationship corresponding to each displacement interval.

[0050] Specifically, the rotor position is recorded at a fixed time interval t during the movement of the rotor. The displacement interval is the displacement difference between two adjacent displacement drive values ​​within the fixed time interval. The corresponding bias coefficient is calculated for each displacement interval, and different bias coefficients K1, K2, etc. are obtained respectively. These bias coefficients are recorded and stored, that is, all bias coefficients of different displacement intervals are obtained. The bias coefficient is calculated by the ratio of the difference between the first corresponding relationship and the second corresponding relationship corresponding to each displacement interval, such as Figure 3 As shown, the bias coefficient of the present invention is compared with the existing bias coefficient, wherein the solid line is the bias coefficient curve calculated for each displacement interval of the present invention, and the straight line is the fixed bias coefficient of the prior art.

[0051] For example, taking the Y axis as an example, the magnetic bearing is driven by the controller to make the rotor axis first reach the maximum position in the negative direction of the Y axis, that is, the minimum position of the displacement sensor range, which is defined as DY-. Taking this as the starting point, the rotor axis begins to move to the maximum position in the positive direction of the Y axis at a slow and constant speed. During the movement, the displacement drive value D0 and the displacement detection value D0' are sampled, recorded and stored at a fixed time interval t until the rotor axis reaches the maximum position in the positive direction of the Y axis, that is, the maximum position in the positive direction of the displacement sensor, which is defined as DY. Taking this as the end point, the time used in the process is recorded as T, then T / t points are collected, corresponding to D0 and D0', D1 and D1'..., with D0 to D1 as a displacement interval, D0 and D0' are calculated for difference, and a bias coefficient K0 is obtained. Similarly, all displacement intervals are calculated for difference, and different bias coefficients K1, K2... are obtained respectively. These bias coefficients are recorded and stored, that is, all bias coefficients of different displacement intervals are obtained.

[0052] In some embodiments, the calibration method also includes: differentially processing the excitation source signal sent to the displacement sensor to obtain the current midpoint voltage, wherein the excitation source signal is two opposite signals of the same frequency; differentially processing the current displacement detection value to obtain a first differential signal; differentially processing the first differential signal and the current midpoint voltage to obtain a second differential signal; filtering, biasing and amplifying the second differential signal to obtain a new displacement detection signal; and updating the current displacement detection value to a new displacement detection signal.

[0053] Specifically, Figure 4As shown, the controller sends an excitation source signal to the displacement sensor, performs differential processing to obtain the current midpoint voltage, and performs differential processing on the current displacement detection value to obtain the first differential signal. The midpoint voltage can be understood as a voltage compared with the first differential signal. By comparing the first differential signal with the midpoint voltage, the deviation value between the current position of the rotor and the initial position is obtained. When the controller sends an excitation source signal to the displacement sensor without performing differential processing to obtain the current midpoint voltage, the first differential signal is compared with the ground terminal voltage, that is, compared with the 0V voltage. Since the excitation source signal sent is a square wave signal of a certain frequency, when the square wave signal switches between high and low levels, it is easy to generate a spike voltage that is not 0V to the ground, which disrupts the subsequent displacement signal sampling, and uses differential processing. When the current midpoint voltage is obtained for comparison operation, since both signals come from the excitation source signal generated by the controller and change at the same frequency, this influence can be completely avoided; the first differential signal and the current midpoint voltage are differentially processed to obtain the second differential signal, and the second differential signal is filtered to filter the displacement signal to make the signal cleaner. Since the rotor has different bias coefficients in different displacement intervals, in order to make the displacement sensor more accurate, the filtered second differential signal is biased according to the bias coefficient of the current displacement interval to reduce the error displacement sensor detection error, and then the second differential signal is amplified to obtain a new displacement detection signal and sent to the controller, and the current displacement detection value in the controller is updated to the new displacement detection signal.

[0054] For example, Figure 4 As shown in the figure, L1, L2, L3 and L4 are four coils of the inductive displacement sensor. According to the principle of electromagnetic induction, the motor rotor displacement distance can be converted into an electrical signal and transmitted to the controller. Taking the Y1 axis as an example, the Y1+ and Y1- signals from the same degree of freedom are received, and the two signals are differentially processed by the operational amplifier circuit to obtain a first differential signal; the excitation source signals DRV-A and DRV-B signals sent by the controller are differentially processed by the operational amplifier circuit to obtain a new midpoint voltage, that is, the current midpoint voltage, and the first differential signal and the current midpoint voltage are differentially processed to obtain a second differential signal; the second differential signal is filtered to make the signal cleaner, the second differential signal is biased, the deviation value generated in the process of signal acquisition and transmission is compensated, and the signal level is processed to be suitable for the level range input to the controller, and finally the current displacement detection value is updated to a new displacement detection signal.

[0055] A second aspect of the present invention provides a calibration circuit for a displacement sensor, wherein the displacement sensor is used to detect the rotor position of a magnetic bearing system, such as Figure 5 As shown, the calibration circuit 100 includes: a differential processing module 110 , a bias amplification processing module 120 and a controller 130 .

[0056] Among them, the differential processing module 110 is used to perform differential processing according to the displacement detection value of the displacement sensor and the excitation source signal of the displacement sensor to obtain a differential signal; the bias amplification processing module 120 is used to perform bias amplification processing on the differential signal to obtain the displacement detection signal of the displacement sensor; the controller 130 is connected to the bias amplification processing module 120 and the displacement sensor, and is used to obtain the current displacement detection value of the displacement sensor, determine that the current displacement detection value is in the target displacement interval of the target degree of freedom mapping relationship, and offset compensate the displacement sensor according to the bias coefficient of the target displacement interval. The target degree of freedom mapping relationship is the corresponding relationship between the displacement value of the target degree of freedom and time.

[0057] Specifically, the differential processing module 110 receives the displacement detection value of the displacement sensor and the excitation source signal of the displacement sensor, and performs differential processing on the displacement detection value of the displacement sensor and the excitation source signal of the displacement sensor to obtain a differential signal; after obtaining the differential signal, the differential processing module 110 sends the differential signal to the bias amplification processing module 120, and the bias amplification processing module 120 performs bias processing on the differential signal, compensates for the deviation value generated during the signal acquisition and transmission process, and processes the signal level to a level range suitable for input to the controller 130; the controller 130 receives the new displacement detection signal after the differential processing, and simultaneously obtains the current displacement detection value of the displacement sensor, determines that the current displacement detection value is in the target displacement interval of the target degree of freedom mapping relationship, and performs bias compensation on the displacement sensor according to the bias coefficient of the target displacement interval to reduce the measurement error of the displacement sensor, and finally updates the current displacement detection value to a new displacement detection signal.

[0058] According to the calibration circuit of the displacement sensor of the embodiment of the present invention, after the controller obtains the current displacement detection value of the displacement sensor, it determines the target displacement interval, and dynamically compensates the displacement sensor according to the bias coefficient in different target displacement intervals, thereby improving the measurement accuracy of the displacement sensor and the stability of the magnetic bearing system. There is no need to manually adjust the components in the circuit for bias compensation, which reduces the complexity of operation and avoids erroneous operations.

[0059] In some embodiments, Figure 5 As shown, the differential processing module 110 includes: a first operational amplifier circuit 111 , a second operational amplifier circuit 112 , and a third operational amplifier circuit 113 .

[0060] Among them, the input end of the first operational amplifier circuit 111 is the displacement detection value of the displacement sensor, which is used to perform differential processing on the displacement detection value to output a first differential signal; the input end of the second operational amplifier circuit 112 is the excitation source signal, which is used to perform differential processing on the excitation source signal to obtain the current midpoint voltage, and the excitation source signal is two same-frequency reverse signals; the input end of the third operational amplifier circuit 113 is connected to the output end of the first operational amplifier circuit 111 and the output end of the second operational amplifier circuit 112, and is used to perform differential processing on the first differential signal and the current midpoint voltage to obtain a second differential signal.

[0061] Specifically, the controller 130 controls the rotor to move, and at this time the displacement sensor detects the rotor position. The input end of the first operational amplifier circuit 111 receives the displacement detection value of the displacement sensor, and performs differential processing on the displacement detection value to output a first differential signal; the controller 130 generates a set of DRV-A and DRV-B square wave signals of the same frequency and opposite directions through PWM (Pulse Width Modulation, pulse width modulation technology) as the excitation source signal of the displacement sensor, and the second operational amplifier circuit 112 receives the excitation source signal, and performs differential processing on the excitation source signal to obtain the current midpoint voltage; the third operational amplifier circuit 113 receives the signals sent by the first operational amplifier circuit 111 and the second operational amplifier circuit 112. After receiving the signals sent by the first operational amplifier circuit 111 and the second operational amplifier circuit 112, the third operational amplifier circuit 113 performs differential processing on the first differential signal and the current midpoint voltage to obtain a second differential signal.

[0062] In some embodiments, Figure 5 As shown, the bias amplification processing module 120 includes: a first resistor 121 , a fourth operational amplifier circuit 122 and a second resistor 123 .

[0063] Among them, the first end of the first resistor 121 is connected to the output end of the third operational amplifier circuit 113 and the first end of the inductor of the first digital potentiometer 101 of the displacement sensor, the second end of the first resistor 121 is connected to the adjustment end of the second digital potentiometer 102 of the displacement sensor, the first resistor 121 is used to adjust the bias of the inductor of the first digital potentiometer 101, and the first digital potentiometer 101 and the second digital potentiometer 102 are used to detect displacement signals of the same degree of freedom; the first input end of the fourth operational amplifier circuit 122 is connected to the first end of the first resistor 121, the output end of the third operational amplifier circuit 113, and the first end of the inductor of the first digital potentiometer 101, the output end of the fourth operational amplifier circuit 122 is connected to the second end of the inductor of the first digital potentiometer 101, and is used to amplify the second differential signal; the first end of the second resistor 123 is connected to the output end of the fourth operational amplifier circuit 122, and the second end of the second resistor 123 is connected to the A / D (Analog to Digital Converter) port of the controller 130, and is used to transmit the displacement detection signal.

[0064] Specifically, the third operational amplifier circuit 113 outputs the second differential signal to the bias amplification processing module 120, and the second differential signal is sent to the fourth operational amplifier circuit 122 to amplify the second differential signal. At the same time, the first resistor 121 adjusts the bias of the inductance of the first digital potentiometer 101 to make the displacement sensor detect accurately. The amplified second differential signal is transmitted to the A / D port of the controller through the second resistor 123. The controller converts the received analog signal into a digital signal and updates the current displacement detection value to a new displacement detection signal.

[0065] In some embodiments, Figure 5 As shown, the calibration circuit 100 further includes a capacitor 103 .

[0066] Among them, the first end of the capacitor 103 is connected to the first end of the inductor of the first digital potentiometer 101, and the second end of the capacitor 103 is connected to the second end of the inductor of the first digital potentiometer 101 and the adjustment end of the inductor of the first digital potentiometer 101. When the calibration circuit 100 is working, the capacitor 103 is used to change the output voltage waveform of the circuit, smooth the output voltage to a certain extent, and reduce the generation of glitches.

[0067] In some embodiments, the controller 130 is connected to the first digital potentiometer 101 and the second digital potentiometer 102 via SPI (Serial Peripheral Interface) to send the bias coefficient to the displacement sensor; the controller 130 is also connected to the input end of the second operational amplifier circuit 112 to send an excitation source signal.

[0068] Specifically, Figure 5As shown, the controller 130 generates a set of DRV-A and DRV-B square wave signals of the same frequency and opposite direction through PWM as the driving signal of the displacement sensor. At the same time, the controller 130 receives the feedback signal from the displacement sensor, compares it with the control signal, and calculates the real-time bias coefficient of the displacement sensor of the magnetic bearing system. After all the different bias coefficients are obtained, when the displacement sensor performs displacement sampling, the collected displacement detection value is located in which displacement interval. The controller 130 sends the bias coefficient K corresponding to this displacement interval to the first digital potentiometer 101 and the second digital potentiometer 102 through SPI communication, thereby realizing dynamic compensation of the displacement sensor.

[0069] By way of example, the present invention improves the signal processing accuracy and real-time adjustment capability of the displacement sensor by changing and optimizing the calibration method, divides the maximum stroke of the rotor into segments, drives the magnetic bearing to simulate the running trajectory of the rotor within the maximum stroke, and sets an excitation source. After comparing the actual displacement signals of different segments received by the controller with the theoretical displacement signals, the offsets in different segments are calculated, and when the rotor is in different displacement stages, the offsets of different segments are sent to the digital potentiometer.

[0070] In some embodiments, the calibration circuit includes two differential processing modules and two offset amplification processing modules.

[0071] Among them, a differential processing module and a bias amplification processing module are connected to the first digital potentiometer and the second digital potentiometer for detecting the displacement signal of the first degree of freedom of the rotor, and another differential processing module and another bias amplification processing module are connected to the first digital potentiometer and the second digital potentiometer for detecting the displacement signal of the second degree of freedom of the rotor.

[0072] Specifically, Figure 4 As shown, there are four coils around the rotor of the inductive displacement sensor, and every two relative position coils are used to detect the displacement signal of one degree of freedom of the rotor. For example, the first degree of freedom can be the up and down direction or the left and right direction. If the first degree of freedom is the up and down direction, the second degree of freedom is the left and right direction. If the first degree of freedom is the left and right direction, the second degree of freedom is the up and down direction; a differential processing module and a bias amplification processing module are connected to two digital potentiometers used to detect the displacement signal of the first degree of freedom of the rotor. Therefore, two differential processing modules and two bias amplification processing modules are required to detect the displacement signals of the two degrees of freedom of the rotor.

[0073] A third aspect of the present invention provides a flywheel energy storage device, such as Figure 6 As shown, the flywheel energy storage device 200 includes: a displacement sensor 201 , a flywheel 202 , a magnetic bearing system 203 and a calibration circuit 100 .

[0074] According to the flywheel energy storage device of the embodiment of the present invention, the displacement sensor can be dynamically biased according to the bias coefficient in different target displacement intervals, thereby improving the measurement accuracy of the displacement sensor and the stability of the magnetic bearing system. There is no need to manually adjust the components in the circuit for bias compensation, which reduces the complexity of operation and avoids erroneous operations, thereby improving the accuracy and stability of the flywheel energy storage device and reducing energy consumption.

[0075] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example.

[0076] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for calibrating a displacement sensor, characterized in that: The displacement sensor is used to detect the rotor position of the magnetic bearing system, and the calibration method includes: Get the current displacement detection value of the displacement sensor; Determining that the current displacement detection value is in a target displacement interval of a target degree of freedom mapping relationship, wherein the target degree of freedom mapping relationship is a correspondence between a displacement value of a target degree of freedom and time; performing bias compensation on the displacement sensor according to the bias coefficient of the target displacement interval; The target degree of freedom mapping relationship is obtained according to the following steps: The rotor is driven to operate with the displacement driving value, so that the rotor moves from the maximum position in the negative direction of the target freedom axis to the maximum position in the positive direction at a preset speed, and the displacement driving value and the displacement detection value of the displacement sensor are recorded at preset time intervals; The target degree of freedom mapping relationship includes a first corresponding relationship between the displacement driving value and time and a second corresponding relationship between the displacement detection value and time during a period when the rotor moves from a negative direction maximum position to a positive direction maximum position of the target degree of freedom axis; The displacement interval is the displacement difference between two adjacent displacement drive values, each displacement interval has a corresponding bias coefficient, and the bias coefficient is the ratio of the difference between the first corresponding relationship and the second corresponding relationship corresponding to each displacement interval.

2. The calibration method according to claim 1, characterized in that: The calibration method further comprises: Performing differential processing on the excitation source signal sent to the displacement sensor to obtain the current midpoint voltage, wherein the excitation source signal is two signals of the same frequency and opposite directions; Performing differential processing on the current displacement detection value to obtain a first differential signal; Performing differential processing on the first differential signal and the current midpoint voltage to obtain a second differential signal; filtering, biasing and amplifying the second differential signal to obtain a new displacement detection signal; The current displacement detection value is updated to the new displacement detection signal.

3. A calibration circuit for a displacement sensor, characterized in that: The displacement sensor is used to detect the rotor position of the magnetic bearing system, and the calibration circuit includes: A differential processing module, used for performing differential processing according to a displacement detection value of the displacement sensor and an excitation source signal of the displacement sensor to obtain a differential signal; An offset amplification processing module, used for performing offset amplification processing on the differential signal to obtain a displacement detection signal of the displacement sensor; a controller, the controller being connected to the bias amplification processing module and the displacement sensor, and being used for obtaining a current displacement detection value of the displacement sensor, determining that the current displacement detection value is in a target displacement interval of a target degree of freedom mapping relationship, and performing bias compensation on the displacement sensor according to a bias coefficient of the target displacement interval, wherein the target degree of freedom mapping relationship is a corresponding relationship between a displacement value of a target degree of freedom and time; The target degree of freedom mapping relationship is obtained according to the following steps: The rotor is driven to operate with the displacement driving value, so that the rotor moves from the maximum position in the negative direction of the target freedom axis to the maximum position in the positive direction at a preset speed, and the displacement driving value and the displacement detection value of the displacement sensor are recorded at preset time intervals; The target degree of freedom mapping relationship includes a first corresponding relationship between the displacement driving value and time and a second corresponding relationship between the displacement detection value and time during a period when the rotor moves from a negative direction maximum position to a positive direction maximum position of the target degree of freedom axis; The displacement interval is the displacement difference between two adjacent displacement drive values, each displacement interval has a corresponding bias coefficient, and the bias coefficient is the ratio of the difference between the first corresponding relationship and the second corresponding relationship corresponding to each displacement interval.

4. The calibration circuit of the displacement sensor according to claim 3, characterized in that: The differential processing module comprises: a first operational amplifier circuit, wherein an input end of the first operational amplifier circuit is a displacement detection value of the displacement sensor, and is used for performing differential processing on the displacement detection value to output a first differential signal; A second operational amplifier circuit, wherein the input end of the second operational amplifier circuit is the excitation source signal, and is used to perform differential processing on the excitation source signal to obtain a current midpoint voltage, wherein the excitation source signal is two same-frequency and opposite-direction signals; A third operational amplifier circuit, wherein the input end of the third operational amplifier circuit is connected to the output end of the first operational amplifier circuit and the output end of the second operational amplifier circuit, and is used for performing differential processing on the first differential signal and the current midpoint voltage to obtain a second differential signal.

5. The calibration circuit of the displacement sensor according to claim 4, characterized in that: The bias amplification processing module comprises: a first resistor, wherein a first end of the first resistor is connected to an output end of the third operational amplifier circuit and a first end of an inductor of a first digital potentiometer of the displacement sensor, a second end of the first resistor is connected to an adjustment end of a second digital potentiometer of the displacement sensor, the first resistor is used to adjust a bias of the inductor of the first digital potentiometer, and the first digital potentiometer and the second digital potentiometer are used to detect a displacement signal of the same degree of freedom; a fourth operational amplifier circuit, wherein a first input end of the fourth operational amplifier circuit is connected to a first end of the first resistor, an output end of the third operational amplifier circuit, and a first end of the inductor of the first digital potentiometer, and an output end of the fourth operational amplifier circuit is connected to a second end of the inductor of the first digital potentiometer, and is used for amplifying the second differential signal; A second resistor, wherein a first end of the second resistor is connected to the output end of the fourth operational amplifier circuit, and a second end of the second resistor is connected to the A / D port of the controller for transmitting a displacement detection signal.

6. The calibration circuit of the displacement sensor according to claim 5, characterized in that: The calibration circuit further comprises: A capacitor, wherein a first end of the capacitor is connected to a first end of the inductor of the first digital potentiometer, and a second end of the capacitor is connected to a second end of the inductor of the first digital potentiometer and an adjustment end of the inductor of the first digital potentiometer.

7. The calibration circuit of the displacement sensor according to claim 5, characterized in that: The controller is connected to the first digital potentiometer and the second digital potentiometer via SPI, and is used to send the bias coefficient to the displacement sensor; The controller is also connected to the input end of the second operational amplifier circuit for sending the excitation source signal.

8. The calibration circuit of the displacement sensor according to claim 5, characterized in that: The calibration circuit includes two differential processing modules and two bias amplification processing modules, wherein one differential processing module and one bias amplification processing module are connected to the first digital potentiometer and the second digital potentiometer for detecting the displacement signal of the first degree of freedom of the rotor, and another differential processing module and another bias amplification processing module are connected to the first digital potentiometer and the second digital potentiometer for detecting the displacement signal of the second degree of freedom of the rotor.

9. A flywheel energy storage device, characterized in that: The invention comprises a flywheel, a magnetic bearing system, a displacement sensor and a calibration circuit of the displacement sensor according to any one of claims 3 to 8.

Images