Linear Hall sensor fault detection method and device and rotor angle measurement method

Abstract

The invention discloses a linear Hall sensor fault detection method and device and a rotor angle measurement method, and relates to the field of sensor fault detection.At least four linear Hall sensors are arranged around a rotor every 90-degree electrical angle and used for measuring the rotor angle in a magnetic suspension pump cavity; for each pair of opposite linear Hall sensors, the fault detection method comprises the steps that in the working process of the magnetic suspension pump, the voltage median and the voltage change amplitude of differential voltage signals output by the two opposite linear Hall sensors in a period are obtained, and the period refers to the duration of at least one circle of rotation of a rotor; and if the voltage median and the voltage change amplitude of the differential voltage signal both exceed the set normal range, the pair of linear Hall sensors break down. According to the method, when the linear Hall sensor breaks down, timely recognition and alarm shutdown can be achieved, and the magnetic suspension pump is prevented from running all the time in a wall collision mode.

Description

Technical Field

[0001] The present invention relates to the field of sensor fault detection, and in particular to a linear Hall sensor fault detection method, device and rotor angle measurement method. Background Art

[0002] The magnetic levitation pump is a pump device that uses magnetic levitation technology to achieve contactless suspension of the rotor. It has the characteristics of high efficiency, low noise and long life, and is widely used in medical, aerospace and other fields. Its core component is a bearingless motor, which uses a magnetic field to achieve precise control of the rotor position and angle. In order to achieve stable control of the rotor, it is crucial to accurately measure the rotor angle. Traditional angle measurement methods include photoelectric encoders, magnetoelectric sensors, etc., but these methods have problems such as complex structure and difficulty in installation and debugging.

[0003] Considering the use of linear Hall sensor rotor angle measurement method can effectively solve the above problems. However, in actual use, when the linear Hall sensor is damaged, it may cause angle measurement errors, thus affecting the stable operation of the magnetic levitation pump. Summary of the invention

[0004] In view of the above problems and technical requirements, the inventors have proposed a linear Hall sensor fault detection method, device and rotor angle measurement method, which can simplify the angle measurement system structure, reduce costs, and timely identify when a linear Hall sensor fails. The technical solution of the present invention is as follows:

[0005] In a first aspect, the present application provides a linear Hall sensor fault detection method, wherein at least four linear Hall sensors are arranged around the rotor at 90° electrical angle positions, respectively, to measure the rotor angle in the magnetic levitation pump cavity;

[0006] For each pair of opposing linear Hall sensors, the fault detection method includes the following steps:

[0007] During the operation of the magnetic levitation pump, the voltage median and voltage variation amplitude of the differential voltage signals output by two relatively linear Hall sensors within a period are obtained, where a period refers to the length of time during which the rotor rotates at least one circle;

[0008] If both the voltage median and the voltage variation amplitude of the differential voltage signal exceed the set normal range, the pair of linear Hall sensors fails.

[0009] A further technical solution is that, for each pair of relative linear Hall sensors, the fault detection method further comprises:

[0010] Before the magnetic levitation pump is put into operation, the voltage median and voltage change amplitude of the differential voltage signal output by two relatively linear Hall sensors within a period are obtained through open-loop operation. A period refers to the length of time it takes for the rotor to rotate one circle.

[0011] If both the voltage median and the voltage variation amplitude of the differential voltage signal exceed the set normal range, the pair of linear Hall sensors fails.

[0012] A further technical solution is to obtain the voltage median and voltage variation amplitude of the differential voltage signal output by two relatively linear Hall sensors within a period, including:

[0013] Determine the maximum value Vmax and the minimum value Vmin of the differential voltage signal output by two relatively linear Hall sensors within a period;

[0014] According to the maximum value Vmax and the minimum value Vmin of the differential voltage signal, the voltage median M and the voltage change amplitude A of the differential voltage signal within a period are calculated and expressed as:

[0015] M=(Vmax+Vmin) / 2, A=(Vmax-Vmin) / 2.

[0016] A further technical solution is to obtain the voltage median and voltage variation amplitude of the differential voltage signal output by two relatively linear Hall sensors within a period through open-loop operation, including:

[0017] A fixed d-axis current is given to the magnetic suspension pump motor, and the rotor is pulled to the electrical angle position of 0°, and then the electrical angle is increased by 1 at fixed time intervals until it reaches 360°, so that the rotor rotates one circle;

[0018] Determine the maximum value Vmax and the minimum value Vmin of the differential voltage signal output by the two relatively linear Hall sensors within this circle;

[0019] According to the maximum value Vmax and the minimum value Vmin of the differential voltage signal, the voltage median M and the voltage change amplitude A of the differential voltage signal within a period are calculated and expressed as:

[0020] M=(Vmax+Vmin) / 2, A=(Vmax-Vmin) / 2.

[0021] A further technical solution is that, for each pair of relative linear Hall sensors, the fault detection method further comprises:

[0022] If the differential voltage signals output by two relatively linear Hall sensors are always fixed in a period, then both linear Hall sensors of the pair are faulty.

[0023] In a second aspect, the present application further provides a linear Hall sensor fault detection device, wherein at least four linear Hall sensors are arranged at 90° electrical angle positions around the rotor, respectively, for measuring the rotor angle in the magnetic levitation pump cavity; the device comprises:

[0024] The first calculation module is used to obtain the voltage median and voltage change amplitude of the differential voltage signals output by two pairs of relatively linear Hall sensors within a period during the operation of the magnetic levitation pump, wherein a period refers to the length of time during which the rotor rotates at least one circle;

[0025] The fault determination module is used, for each pair of opposite linear Hall sensors, to determine that the pair of linear Hall sensors has a fault when the voltage median and voltage variation amplitude of the differential voltage signals output by the pair of linear Hall sensors exceed a set normal range.

[0026] Its further technical solution is that the device also includes:

[0027] The second calculation module is used to obtain the voltage median and voltage change amplitude of the differential voltage signals output by two pairs of relatively linear Hall sensors within a period through open-loop operation before the magnetic levitation pump is put into operation. A period refers to the length of time it takes for the rotor to rotate one circle.

[0028] In a third aspect, the present application also provides a rotor angle measurement method based on a linear Hall sensor, comprising the following steps:

[0029] At least four linear Hall sensors are arranged at 90° electrical angle positions around the rotor in the magnetic levitation pump cavity, and the linear Hall sensors are used to output analog voltage signals that vary with the magnetic field strength of the rotor;

[0030] The MCU samples the differential voltage signal output by each pair of relatively linear Hall sensors, and performs an inverse tangent operation on the two differential voltage signal sampling values ​​to obtain the rotor angle information;

[0031] During the operation of the magnetic levitation pump or before it is put into operation, each pair of relative linear Hall sensors is monitored for failure to ensure the accuracy of the calculated rotor angle information.

[0032] A further technical solution is that the MCU samples the differential voltage signal output by each pair of relatively linear Hall sensors, including:

[0033] The analog voltage signals output by each pair of relatively linear Hall sensors enter the corresponding signal processing circuit for differential and amplification processing to obtain the differential voltage signals output by the pair of relatively linear Hall sensors, which are then output to the AD sampling port of the MCU for real-time sampling.

[0034] A further technical solution is that, in the signal processing circuit:

[0035] Add a midpoint potential signal to the non-inverting input of the operational amplifier. The midpoint potential signal is half of the linear Hall sensor supply voltage Vcc. Then the differential voltage calculation formula of the pair of relative linear Hall sensors is:

[0036] Vout=0.5*(V H1 -V H3 )+Vcc / 2;

[0037] Where V H1 、V H3 These are the analog voltage signals output by two relatively linear Hall sensors.

[0038] The beneficial technical effects of the present invention are:

[0039] The rotor angle measurement method proposed in this application realizes a simple, low-cost and high-precision angle measurement scheme by differential processing of the output signal of the linear Hall sensor. The proposed fault detection method can timely identify and alarm and shut down when a linear Hall sensor fails, preventing the magnetic levitation pump from running into a wall. The detection of Hall faults is divided into damage during operation of the magnetic levitation pump and damage before operation. Damage during operation can be detected in real time using the above-mentioned fault detection method; for damage before operation, it is proposed to detect whether the linear Hall sensor is faulty through open-loop operation before the magnetic levitation pump is put into operation, thereby enhancing the reliability and robustness of the magnetic levitation pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic diagram of the linear Hall output voltage magnitude varying with magnetic field provided by the present application.

[0041] Figure 2 This is a schematic diagram of the installation of the linear Hall sensor provided by the present application in the magnetic levitation pump cavity.

[0042] Figure 3 This is a curve of magnetic field intensity variation induced by two linear Hall sensors with a 90° electrical angle difference provided by the present application.

[0043] Figure 4 It is a schematic diagram of a signal processing circuit provided by this application.

[0044] Figure 5 This is a flow chart of the linear Hall sensor fault detection method provided in this application.

[0045] Figure 6 It is a schematic diagram of a linear Hall sensor fault detection device provided in this application. DETAILED DESCRIPTION

[0046] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings.

[0047] This application addresses the defects of the magnetic levitation pump system and existing angle measurement solutions, and proposes the use of a linear Hall sensor to measure the rotor angle information in the pump cavity. The magnetic levitation pump uses the electromagnetic force generated by the stator coil in the bearingless motor to support and rotate the rotor without contact. By controlling the excitation current in the motor torque winding and the suspension winding coil, precise control of the rotor position and speed is achieved. The rotor is suspended in the pump cavity and is not limited by friction and mechanical wear, thereby improving the efficiency and life of the pump.

[0048] Linear Hall sensors measure rotor position and angle by sensing changes in magnetic field strength. The rotor of a magnetic levitation pump usually contains a set of permanent magnets or attached magnetic materials. When the rotor rotates, the magnetic field around it changes accordingly. The relationship between the linear Hall output voltage and the magnetic field is as follows: Figure 1 As shown in the figure, when the magnetic field strength is 0 (magnetic field at the junction of the N pole and the S pole), the output voltage value of the linear Hall sensor is half of the supply voltage Vcc. Within a certain range, as the magnetic field strength increases or decreases, the output voltage value of the Hall sensor also increases or decreases linearly. When the rotor magnetic field strength is determined and the installation position of the Hall sensor is determined, the range of the Hall sensor output voltage is also determined. Compared with traditional angle measurement solutions, linear Hall sensors have the advantages of simple structure, low cost, and easy integration.

[0049] However, a linear Hall sensor can only measure angles in the range of 0 to 180°. To measure the angle change in the range of 0 to 360°, at least two linear Hall sensors are required. By evenly arranging multiple linear Hall sensors around the rotor, the changes in the rotor magnetic field can be obtained in real time, thereby calculating the angle of the rotor. The specific principle is as follows: the linear Hall sensor can directly sense the magnetic field generated by the rotor and output an analog voltage signal proportional to the magnetic field strength. When the rotor rotates, the direction and intensity of the magnetic field will change accordingly, causing the output voltage of the Hall sensor to show periodic changes. By analyzing the voltage signals output by multiple linear Hall sensors, combined with the known sensor layout position and rotor magnetic field characteristics, the instantaneous angle of the rotor can be calculated. In addition, the use of multiple linear Hall sensors can not only improve the accuracy of angle measurement, but also reduce the impact of noise and interference through differential processing.

[0050] Based on the above principle, an embodiment of the present application provides a rotor angle measurement method based on a linear Hall sensor, which specifically includes the following contents:

[0051] In order to improve the angle measurement accuracy and anti-interference ability, this embodiment uses four linear Hall sensors H1, H2, H3, and H4, which are arranged at 90° electrical angle positions around the rotor 2 in the magnetic suspension pump cavity 1. Figure 2 As shown in the figure, it is assumed that four linear Hall sensors are arranged at four key positions around the rotor (such as 0°, 90°, 180° and 270°). When the rotor rotates, the magnetic field intensity sensed by the sensor presents a sinusoidal change, such as Figure 3 Then, the MCU samples the differential voltage signal output by each pair of relatively linear Hall sensors, and performs an inverse tangent operation on the two differential voltage signal sampling values ​​AD1 and AD2 to obtain the rotor angle information:

[0052]

[0053] Each pair of relative linear Hall sensors can be understood as linear Hall sensors H1 and H3 being a pair of differential signal combinations, and linear Hall sensors H2 and H4 being a pair of differential signal combinations. As the rotor rotates, the sine signal and cosine signal of the rotor position can be obtained respectively. Using a pair of signals for differential processing can eliminate system noise and interference, thereby obtaining a more accurate angle signal.

[0054] The differential voltage signal output by each pair of relatively linear Hall sensors is sampled by the MCU, specifically including: the analog voltage signal output by each pair of relatively linear Hall sensors enters the corresponding signal processing circuit for differential and amplification processing, and then obtains the differential voltage signal (i.e., sine signal or cosine signal) output by the pair of relatively linear Hall sensors, and outputs it to the AD sampling port of the MCU for real-time sampling, and finally obtains two differential voltage signal sampling values ​​AD1 and AD2. The signal processing circuit structure of linear Hall sensors H1 and H3 is referenced Figure 4 As shown, the analog voltage signal V output by the linear Hall sensor H1 H1 After passing through two magnetic beads and resistors, it is connected to the in-phase input terminal of the operational amplifier U1. Similarly, the analog voltage signal V output by the linear Hall sensor H3 is H3 After passing through two magnetic beads and resistors in sequence, it is connected to the inverting input terminal of the operational amplifier U1. A filter capacitor is connected between the output terminals of each magnetic bead. The input signal can effectively prevent external interference through the filtering of the magnetic beads and capacitors. A feedback resistor is connected between the inverting input terminal and the output terminal of the operational amplifier U1. The output terminal of the operational amplifier U1 is connected to the AD sampling port of the MCU through the first resistor. A filter capacitor is connected between the first resistor and the AD sampling port, and the capacitor is grounded. Then the signal V H1 and V H3After passing through this circuit, the MCU can sample and obtain the sample value AD1. The signal processing circuit structure of the linear Hall sensor H2 and H4 is the same. The analog voltage signal V output by the sensor H2 and V H4 After passing through this circuit, the sample value AD2 can be obtained by sampling by MCU.

[0055] Since the linear Hall sensor outputs an analog voltage signal, the MCU needs to sample the analog value to calculate the rotor position, and the analog voltage signal sampled into the MCU cannot be a negative value, so it is necessary to add a midpoint potential signal at the in-phase input of the operational amplifier U1. The midpoint potential signal is half of the linear Hall sensor power supply voltage Vcc, which is 2.5V in this embodiment. After adding this midpoint potential signal, the differential voltage calculation formula of a pair of relative linear Hall sensors is:

[0056] Vout = 0.5*(V H1 -V H3 )+Vcc / 2 (2)

[0057] However, in actual use, when a linear Hall sensor fails, such as when the sensor is damaged or the output is abnormal, the sensor output voltage cannot reflect the actual position of the rotor. At this time, the rotor angle obtained by the above angle measurement method has a deviation, thereby affecting the stable operation of the magnetic levitation pump. Therefore, this application designs a linear Hall sensor fault detection method, the principle of which is as follows:

[0058] Taking the linear Hall sensor supply voltage of 5V as an example, when the magnetic field strength is 0, the sensor output voltage is half of the supply voltage, that is, 2.5V. As the rotor rotates, the Hall sensor output voltage changes linearly. Assuming that the amplitude of the voltage change is A (A<2.5), the range of each linear Hall output voltage is 2.5±A. After the differential voltage signal output by each pair of linear Hall sensors passes through the above-mentioned hardware signal processing circuit, the voltage range output to the AD sampling port of the MCU is also 2.5±A.

[0059] When one of the linear Hall sensors is damaged, its output voltage may be in three situations: the sensor output voltage is fixed at 2.5V, 0V or 5V. Taking the pair of linear Hall sensors H1 and H3 as an example, Table 1 lists the various possible situations of damage to the two sensors and the corresponding differential voltage range calculated according to formula (2):

[0060] Table 1. Fault conditions and corresponding differential voltages for a pair of linear Hall sensors

[0061]

[0062]

[0063] From the various combinations of situations in the table above, it can be seen that when one or a pair of Hall sensors are damaged, the differential voltage output by the linear Hall sensor will be different from the differential voltage output under normal circumstances. Similarly, when the H2 and H4 sensors are damaged, the combination of the output differential voltage is the same as in the table above. As long as this difference can be detected, it can be determined that the Hall sensor is faulty.

[0064] Based on the above principle, another embodiment of the present application provides a linear Hall sensor fault detection method, which is integrated in the MCU. Figure 5 As shown, for each pair of opposite linear Hall sensors, the fault detection method includes the following:

[0065] Step 1A: During the operation of the magnetic levitation pump, obtain the voltage median and voltage change amplitude of the differential voltage signal output by the two relatively linear Hall sensors within a period. The differential voltage signal here is the differential voltage signal output by each pair of relatively linear Hall sensors sampled by the MCU. When the rotor rotates, the differential voltage signal changes sinusoidally, and the sampled value obtained by AD sampling also changes accordingly.

[0066] In this step, first determine the maximum and minimum values ​​of the differential voltage signal output by the two relatively linear Hall sensors within a period. A period refers to the length of time that the rotor rotates at least one circle. That is, by sampling the differential voltage value of the Hall signal in real time and comparing it with the maximum and minimum values ​​recorded in the program, take out the result of this comparison to update the maximum and minimum values. Then, when the rotor rotates one circle, the maximum and minimum values ​​of the Hall voltage difference within one circle can be obtained, which are recorded as Vmax and Vmin. Then, according to the maximum and minimum values ​​of the differential voltage signal, the voltage median M and voltage change amplitude A of the differential voltage signal within a period are calculated, which are expressed as:

[0067] M=(Vmax+Vmin) / 2, A=(Vmax-Vmin) / 2 (3)

[0068] Step 2: By judging whether the voltage median and voltage variation amplitude within a period are within the set normal range, it can be judged whether the current Hall output signal is normal. If both the voltage median and voltage variation amplitude exceed the set normal range, the pair of linear Hall sensors fails (one or both may be damaged), and the MCU triggers an alarm signal to stop the system and notify the customer for repair. The set normal range of the voltage median can be half of the sensor power supply voltage, and the neighborhood range centered on this value is taken as the corresponding set normal range, while the set normal range of the voltage variation amplitude depends on the sensor's own output and the magnetic field strength.

[0069] As can be seen from the above method for detecting linear Hall faults, to determine whether the linear Hall is damaged, the rotor must rotate at least one circle to find the voltage median and voltage change amplitude of the differential voltage signal. If the linear Hall is damaged during operation, the rotor will not stop immediately due to inertia, so the above method can be used to detect whether the linear Hall is damaged. However, if the Hall is damaged before operation, the angle value calculated by formula (1) is incorrect, which will cause the magnetic levitation pump to fail to operate normally. For example, the rotor stops at a certain position and does not move, or the calculated angle value is fixed, causing the rotor to fly. At this time, the maximum and minimum values ​​of the Hall differential voltage signal within one circle cannot be effectively collected. Therefore, for each pair of relative linear Hall sensors, the fault detection method also includes:

[0070] Step 1B: Before the magnetic levitation pump is put into operation, the voltage median and voltage variation amplitude of the differential voltage signal output by the two relatively linear Hall sensors within a period are obtained through open-loop operation. In this step, the system is first operated in an open-loop for a short period of time after power is turned on, and the electrical angle used for the rotor operation is fixed to 0° instead of the angle calculated by the linear Hall. Specifically, a fixed d-axis current is given to the magnetic levitation pump motor, and the rotor is pulled to the 0° electrical angle position, and then the electrical angle is increased by 1 at fixed time intervals until it reaches 360°, indicating that the given d-axis current has rotated one circle electrically at this time, and the corresponding rotor has also rotated one circle electrically. Record the maximum and minimum values ​​of the differential voltage signals output by the two relatively linear Hall sensors within one circle, and the voltage median M and voltage variation amplitude A of the differential voltage signal can be calculated by formula (3).

[0071] Finally, perform the same operation as step 2 above to determine whether the linear Hall is normal before the system is put into operation. If a pair of linear Hall sensors is detected to be faulty, an alarm signal is output and the customer is prompted to repair or replace the Hall. If it is normal, the normal process is entered and waits for operation. Optionally, according to Table 1, if the differential voltage signal output by two relative linear Hall sensors is always a fixed value within a period, then the pair of linear Hall sensors are both faulty.

[0072] Therefore, during the operation of the magnetic levitation pump or before it is put into operation, the fault detection method provided by the present application is used to monitor whether each pair of relative linear Hall sensors has a fault, thereby ensuring the accuracy of the calculated rotor angle information.

[0073] Based on the same inventive concept, another embodiment of the present application provides a linear Hall sensor fault detection device, which is integrated in an MCU. Figure 6As shown, the device includes a first calculation module, a second calculation module and a fault determination module. Wherein: the first calculation module is used to obtain the voltage median and voltage variation amplitude of the differential voltage signals output by two pairs of relative linear Hall sensors in a period during the operation of the magnetic levitation pump, respectively. A period refers to the duration of at least one rotation of the rotor. The second calculation module is used to obtain the voltage median and voltage variation amplitude of the differential voltage signals output by two pairs of relative linear Hall sensors in a period through open-loop operation before the magnetic levitation pump is put into operation, respectively. A period refers to the duration of one rotation of the rotor. The fault determination module is used to receive the voltage median and voltage variation amplitude of the differential voltage signals output by each pair of relative linear Hall sensors in a period output by the first calculation module or the second calculation module, and when the voltage median and voltage variation amplitude both exceed the set normal range, it is determined that the pair of linear Hall sensors has a fault. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above-mentioned fault detection method, so the specific definition in each module can refer to the definition of the linear Hall sensor fault detection method above, which will not be repeated here.

[0074] The above is only a preferred embodiment of the present application, and the present invention is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included in the protection scope of the present invention.

Claims

1. A linear Hall sensor fault detection method, characterized in that: At least four linear Hall sensors are arranged at 90° electrical angle positions around the rotor to measure the rotor angle in the magnetic levitation pump cavity; For each pair of opposing linear Hall sensors, the fault detection method includes: During the operation of the magnetic levitation pump, the voltage median and voltage variation amplitude of the differential voltage signals output by two relatively linear Hall sensors within a period are obtained, wherein the period refers to the duration of at least one rotation of the rotor; If both the voltage median value and the voltage variation amplitude of the differential voltage signal exceed the set normal range, the pair of linear Hall sensors fails.

2. The linear Hall sensor fault detection method according to claim 1, characterized in that: For each pair of opposing linear Hall sensors, the fault detection method further includes: Before the magnetic levitation pump is put into operation, the voltage median and voltage variation amplitude of the differential voltage signal output by two relatively linear Hall sensors within a period are obtained through open-loop operation, wherein a period refers to the length of time for the rotor to rotate one circle; If both the voltage median value and the voltage variation amplitude of the differential voltage signal exceed the set normal range, the pair of linear Hall sensors fails.

3. The linear Hall sensor fault detection method according to claim 1, characterized in that: The step of obtaining a voltage median value and a voltage variation amplitude of a differential voltage signal output by two relatively linear Hall sensors within a period includes: Determine the maximum value Vmax and the minimum value Vmin of the differential voltage signal output by two relatively linear Hall sensors within a period; The voltage median M and the voltage variation amplitude A of the differential voltage signal within a period are calculated according to the maximum value Vmax and the minimum value Vmin of the differential voltage signal, and are expressed as: M=(Vmax+Vmin) / 2, A=(Vmax-Vmin) / 2.

4. The linear Hall sensor fault detection method according to claim 2, characterized in that: The method of obtaining the voltage median and voltage variation amplitude of the differential voltage signals output by two relatively linear Hall sensors within a period through open-loop operation includes: A fixed d-axis current is given to the magnetic suspension pump motor, and the rotor is pulled to the electrical angle position of 0°, and then the electrical angle is increased by 1 at fixed time intervals until it reaches 360°, so that the rotor rotates one circle; Determine the maximum value Vmax and the minimum value Vmin of the differential voltage signal output by the two relatively linear Hall sensors within this circle; The voltage median M and the voltage variation amplitude A of the differential voltage signal within a period are calculated according to the maximum value Vmax and the minimum value Vmin of the differential voltage signal, and are expressed as: M=(Vmax+Vmin) / 2, A=(Vmax-Vmin) / 2.

5. The linear Hall sensor fault detection method according to claim 1 or 2, characterized in that: For each pair of opposing linear Hall sensors, the fault detection method further includes: If the differential voltage signals output by two relatively linear Hall sensors are always fixed in a period, then both linear Hall sensors of the pair are faulty.

6. A linear Hall sensor fault detection device, characterized in that: At least four linear Hall sensors are arranged at 90° electrical angle positions around the rotor to measure the rotor angle in the magnetic levitation pump cavity; the device includes: The first calculation module is used to obtain the voltage median and voltage change amplitude of the differential voltage signals output by two pairs of relatively linear Hall sensors within a period during the operation of the magnetic levitation pump, wherein the period refers to the duration of at least one rotation of the rotor; The fault determination module is used, for each pair of opposite linear Hall sensors, to determine that the pair of linear Hall sensors has a fault when the voltage median and voltage variation amplitude of the differential voltage signals output by the pair of linear Hall sensors exceed a set normal range.

7. The linear Hall sensor fault detection device according to claim 6, characterized in that: The device also includes: The second calculation module is used to obtain the voltage median and voltage change amplitude of the differential voltage signals output by two pairs of relatively linear Hall sensors within a period through open-loop operation before the magnetic levitation pump is put into operation. The period refers to the length of time for the rotor to rotate one circle.

8. A rotor angle measurement method based on a linear Hall sensor, characterized in that: The method comprises: At least four linear Hall sensors are arranged at 90° electrical angle positions around the rotor in the magnetic levitation pump cavity, and the linear Hall sensors are used to output analog voltage signals that vary with the magnetic field strength of the rotor; The MCU samples the differential voltage signal output by each pair of relatively linear Hall sensors, and performs an inverse tangent operation on the two differential voltage signal sampling values ​​to obtain the rotor angle information; During the operation of the magnetic levitation pump or before it is put into operation, each pair of relative linear Hall sensors is monitored for failure to ensure the accuracy of the calculated rotor angle information.

9. The rotor angle measurement method based on the linear Hall sensor according to claim 8, characterized in that: The MCU samples the differential voltage signal output by each pair of relatively linear Hall sensors, including: After the analog voltage signals output by each pair of relatively linear Hall sensors enter the corresponding signal processing circuit for differential and amplification processing, the differential voltage signals output by the pair of relatively linear Hall sensors are obtained, and then output to the AD sampling port of the MCU for real-time sampling.

10. The rotor angle measurement method based on linear Hall sensor according to claim 9, characterized in that: In the signal processing circuit: A midpoint potential signal is added to the non-inverting input terminal of the operational amplifier. The midpoint potential signal is half of the linear Hall sensor power supply voltage Vcc. Then, the differential voltage calculation formula of the pair of relative linear Hall sensors is: Vout=0.5*(V H1 -V H3 )+Vcc / 2; Where V H1 、V H3 These are the analog voltage signals output by two relatively linear Hall sensors.

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