Permanent magnet monitoring system and electric power steering system

Abstract

The utility model relates to the technical field of automobile parts, and provides a permanent magnet monitoring system and an electric power steering system. The permanent magnet monitoring system comprises: a charge generation module for generating free charges; the charge acquisition circuit comprises a sampling resistor and a pair of charge acquisition plates which are connected in series, the charge acquisition plates are arranged close to the ionization position of the free charge, and two magnetic poles of the permanent magnet are respectively arranged close to the pair of charge acquisition plates; and the differential circuit comprises an operational amplifier, two input ends of the operational amplifier are respectively connected with the pair of charge acquisition boards, and an output end of the operational amplifier outputs sampling voltage. The permanent magnet monitoring system provided by the utility model combines the charge generation module, the charge acquisition circuit and the differential circuit, utilizes the characteristic that free charges deflect in the magnetic field of the permanent magnet, monitors the change of the magnetic field intensity in the use process of the permanent magnet, does not need to disassemble the permanent magnet, does not need a special detection instrument, and improves the detection efficiency. Therefore, the aging condition of the permanent magnet can be monitored accurately and conveniently.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of automobile parts, and concretely relates to a permanent magnet monitoring system and an electric power steering system. BACKGROUND

[0002] In the angle sensor and other automobile parts of the electric power steering system, a permanent magnet is assembled. With use, the permanent magnet will gradually age.

[0003] At present, the damage condition of the permanent magnet is mainly observed by naked eyes, or the magnetic flux of the permanent magnet is detected by a special detection instrument to judge the aging degree of the permanent magnet. The naked eye observation mode is not accurate, and the permanent magnet needs to be disassembled. The disassembly process not only consumes a long time, but also easily damages the assembled parts of the permanent magnet. The operation of the special detection instrument for detecting the magnetic flux is complicated and has a high cost.

[0004] It should be noted that the information disclosed in the above background section is only used to strengthen the understanding of the background of the utility model, and therefore can include information that does not constitute prior art known to those of ordinary skill in the art. SUMMARY

[0005] Therefore, the utility model provides a permanent magnet monitoring system, which utilizes the deflection characteristics of free charges in the magnetic field of the permanent magnet to monitor the change of the magnetic field strength in the use process of the permanent magnet, without disassembling the permanent magnet or using a special detection instrument, so that the aging condition of the permanent magnet is accurately and conveniently monitored.

[0006] According to one aspect of the utility model, a permanent magnet monitoring system is provided, which comprises: a charge generation module for generating free charges; a charge collection circuit comprising a sampling resistor and a pair of charge collection plates connected in series, the charge collection plates are arranged close to the ionization position of the free charges, and two magnetic poles of the permanent magnet are arranged close to a pair of the charge collection plates respectively; and a differential circuit comprising an operational amplifier, two input ends of the operational amplifier are connected to a pair of the charge collection plates respectively, and the output end of the operational amplifier outputs a sampling voltage.

[0007] The charge generation module can generate free charges through high voltage, high temperature, etc. The pair of charge collection plates of the charge collection circuit are arranged close to two magnetic poles of the permanent magnet and close to an ionization position of the free charges, so as to collect the free charges moving under the action of the magnetic field of the permanent magnet, for example, the free electrons move to the charge collection plate arranged close to the north pole of the permanent magnet under the action of the magnetic field of the permanent magnet; meanwhile, the charge collection plate accumulating the free charges generates a same repulsive coulomb force on the continuous movement of the free charges, until the magnetic field force and the coulomb force acting on the free charges are equal, then the free charges stop moving, and the charge collection plate is saturated. The two input ends of the operational amplifier of the differential circuit are connected with the pair of charge collection plates, when the charge collection plates discharge to the sampling resistor, the two input ends of the operational amplifier can collect the potential difference between the pair of charge collection plates; in combination with the potential difference collected by the operational amplifier and the sampling voltage output by the operational amplifier, according to the virtual break and virtual short principle of the operational amplifier, the discharge current of the charge collection plate can be calculated. Further, according to the discharge time of the charge collection plate, the discharge current is integrated and operated, so that the charge amount of the pair of charge collection plates can be calculated, and then the magnetic field strength of the permanent magnet can be determined according to the calculation result that the magnetic field force and the coulomb force are equal when the free charges are in force balance.

[0008] Therefore, the permanent magnet monitoring system provided by the utility model combines the charge generation module, the charge collection circuit and the differential circuit, utilizes the deflection characteristics of the free charges in the magnetic field of the permanent magnet, monitors the change of the magnetic field strength during the use of the permanent magnet, and realizes accurate and convenient monitoring of the aging condition of the permanent magnet without disassembling the permanent magnet or using special detection instruments.

[0009] In some embodiments, the charge generation module comprises a high-voltage electrostatic generator, and the charge collection plate is arranged close to an electrode of the high-voltage electrostatic generator.

[0010] The high-voltage electrostatic generator can form a high-voltage electrostatic field between two electrodes, drive the electrodes to ionize free electrons, and the free electrons can move to the charge collection plate arranged close to the north pole of the permanent magnet under the action of the magnetic field of the permanent magnet.

[0011] In some embodiments, the differential circuit further comprises: a first current-limiting resistor connected in series between the first charge collection plate arranged close to the north pole of the permanent magnet and the inverting input end of the operational amplifier; a negative feedback resistor connected between the output end and the inverting input end of the operational amplifier; a second current-limiting resistor connected in series between the second charge collection plate arranged close to the south pole of the permanent magnet and the non-inverting input end of the operational amplifier; and a pull-down resistor connected to the non-inverting input end of the operational amplifier and grounded.

[0012] The differential circuit capable of accurately collecting the potential difference between the pair of charge collection plates is composed of the operational amplifier and the first current-limiting resistor, the second current-limiting resistor, the negative feedback resistor and the pull-down resistor.

[0013] In some embodiments, the operational amplifier satisfies:

[0014]

[0015] wherein U FL1 is the voltage of the first charge collection plate, U FL2 is the voltage of the second charge collection plate, U O1 is the sampling voltage, R2 is the first current-limiting resistor, R3 is the negative feedback resistor, R4 is the second current-limiting resistor, and R5 is the pull-down resistor.

[0016] The output end of the operational amplifier is connected to the controller, and the sampling voltage U O1 output by the output end can be directly measured by the controller. According to the virtual break and virtual short principle of the operational amplifier, the potential difference between the first charge collection plate and the second charge collection plate can be calculated based on the above equation.

[0017] In some embodiments, R2 = R3 = R4 = R5.

[0018] In this way, the potential difference between the first charge collection plate and the second charge collection plate and the discharge current can be easily calculated.

[0019] In some embodiments, the charge collection circuit further has a switch connected in series.

[0020] The switch can be used to conveniently control the on-off of the charge collection circuit. When the charge collection circuit needs to collect free charges, the switch is turned off; when the magnetic field force and the Coulomb force acting on the free charges are equal, the switch is turned on so that the charge collection plates are discharged.

[0021] In some embodiments, the free charges are free electrons, and the charge collection circuit has a charge collection state and a discharge state; in the charge collection state, the switch is turned off, and the free electrons move to the first charge collection plate arranged close to the north pole of the permanent magnet; in the discharge state, the switch is turned on, and a pair of the charge collection plates are discharged.

[0022] In the charge collection state, the switch is turned off, the high-voltage electrostatic generator outputs high-voltage electrostatic to ionize free electrons, and under the action of the magnetic field of the permanent magnet, the free electrons continuously move to the first charge collection plate, so that the potential difference between the first charge collection plate and the second charge collection plate continuously increases. With the continuous gathering of free electrons to the first charge collection plate, the first charge collection plate continues to move to generate a repulsive Coulomb force, and the Coulomb force is opposite to the magnetic field force. When the magnetic field force and the Coulomb force received by the free electron are equal in size, the free electron stops moving, the first charge collection plate is saturated, and the potential difference between the first charge collection plate and the second charge collection plate reaches a maximum value. Then, the electrostatic high-voltage generator stops working, and the switch is closed, so that a closed loop is formed by the charge collection plate, the switch and the sampling resistor, so that the charge collection circuit enters the discharge state, and the charge between the first charge collection plate and the second charge collection plate is neutralized slowly. Since the charge collection plate is connected to the differential circuit, the change of the potential difference between the pair of charge collection plates can be monitored.

[0023] In some embodiments, when the first charge collection plate is saturated, the force on the free electron satisfies:

[0024]

[0025] Wherein, q e is the charge of the free electron, E represents the magnetic field strength of the permanent magnet, k is the Coulomb constant, Q is the charge of the pair of charge collection plates, and l is the distance between the ionization position of the free electron and the first charge collection plate.

[0026] Wherein, the charge Q satisfies: U O1 is the sampling voltage, R1 is the sampling resistor, t1 is the discharge start time of the pair of charge collection plates, and t2 is the discharge end time of the pair of charge collection plates.

[0027] In this way, after calculation, the parameter E representing the magnetic field strength of the permanent magnet can be obtained.

[0028] According to another aspect of the present application, an electric power steering system is provided, wherein the electric power steering system is provided with the permanent magnet monitoring system according to any of the above embodiments, and the permanent magnet is arranged in an angle sensor of the electric power steering system.

[0029] The angle sensor is a core component in an input module of an electric power steering system, and its stability is crucial to safe operation of the electric power steering system. In most angle sensors, the induced magnetic field is provided by a permanent magnet. The permanent magnet is affected by the ambient temperature and humidity during actual operation, and will age to some extent, resulting in weakening of the magnetic field strength. The permanent magnet monitoring system uses the characteristic that free charges are deflected in the magnetic field of the permanent magnet to monitor the gradual weakening of the magnetic induction strength during aging of the permanent magnet, so that the aging of the permanent magnet can be predicted in a timely manner, and the safety of the electric power steering system is improved.

[0030] The beneficial effects of the utility model compared with the prior art at least include:

[0031] The permanent magnet monitoring system provided by the utility model uses the characteristic that free charges are deflected in the magnetic field of the permanent magnet to monitor changes in the magnetic field strength during use of the permanent magnet, without the need to disassemble the permanent magnet or use special detection instruments, so that the aging of the permanent magnet can be accurately and conveniently monitored.

[0032] The permanent magnet monitoring system provided by the utility model can be assembled in an electric power steering system, and can monitor the aging of the permanent magnet in the angle sensor of the electric power steering system in real time, has high precision, can timely warn of aging of the permanent magnet, and ensures the safety and reliability of the electric power steering system.

[0033] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory, and cannot limit the utility model. BRIEF DESCRIPTION OF DRAWINGS

[0034] The drawings incorporated into the specification and forming a part of the specification, show embodiments consistent with the utility model, and together with the specification, serve to explain the principles of the utility model. Obviously, the drawings in the following description are only some embodiments of the utility model, and other drawings can be obtained from these drawings without creative labor for those skilled in the art.

[0035] Figure 1 The structure schematic diagram of the permanent magnet monitoring system in the utility model embodiment is shown;

[0036] Figure 2 The structure schematic diagram of the charge generating module and the charge collection circuit in the utility model embodiment is shown;

[0037] Figure 3 The structure schematic diagram of the differential circuit in the utility model embodiment is shown;

[0038] Figure 4The variation curve of potential difference in the discharging process of the charge collection plate is shown. DETAILED DESCRIPTION

[0039] Example implementations are now described with reference to the drawings. Example implementations can, however, be implemented in many different forms and should not be construed as limited to the implementations set forth herein. Rather, these implementations are provided so that this disclosure will be thorough and complete, and will fully convey the inventive concept to those skilled in the art.

[0040] The accompanying drawings are intended to further explain the present application and are a part of this specification. Identical reference numerals in different drawings represent the same or similar elements.

[0041] The terms "first", "second", and similar terms are used to describe various elements, but do not indicate or imply a quantity or order. In the description of the present application, when it is said that a device is "connected" to another device, it includes not only the case of direct connection, but also the case of indirect connection through other elements.

[0042] It should be noted that the features of the embodiments of the present application and the features in different embodiments can be combined with each other without conflict.

[0043] Figure 1 The structure of the permanent magnet monitoring system is shown, and with reference to Figure 1 The permanent magnet monitoring system provided by the embodiments of the present application comprises:

[0044] The charge generation module 100 is used to generate free charges (which can be negative charges, i.e. free electrons 110a, or positive charges 110b);

[0045] The charge collection circuit 200 comprises a sampling resistor R1 and a pair of charge collection plates (including a first charge collection plate P1 and a second charge collection plate P2) connected in series. The first charge collection plate P1 and the second charge collection plate P2 are arranged close to the ionization position of the free charges, and the two magnetic poles (including the south pole and the north pole) of the permanent magnet are arranged close to the pair of charge collection plates (wherein the north pole of the permanent magnet is arranged close to the first charge collection plate P1, and the south pole of the permanent magnet is arranged close to the second charge collection plate P2);

[0046] The differential circuit 300 comprises an operational amplifier U1. Two input ends (including an inverting input end FL1 and a non-inverting input end FL2) of the operational amplifier U1 are connected to the pair of charge collection plates (wherein the inverting input end FL1 is connected to the first charge collection plate P1, and the non-inverting input end FL2 is connected to the second charge collection plate P2). An output end of the operational amplifier U1 outputs a sampling voltage U O1 .

[0047] The charge generation module 100 can generate free charges by high voltage, high temperature, etc. The pair of charge collection plates of the charge collection circuit 200 are arranged close to the two magnetic poles of the permanent magnet and close to the ionization position of the free charges, so as to collect the free charges moving under the action of the magnetic field of the permanent magnet. For example, the free electron 110a will move to the first charge collection plate P1 arranged close to the north pole of the permanent magnet under the action of the magnetic field of the permanent magnet. At the same time, the charge collection plate accumulating the free charges will generate a repulsive coulomb force on the continuous movement of the free charges, until the magnetic field force and the coulomb force acting on the free charges are equal, then the free charges stop moving, and the charge collection plate is saturated. The two input ends of the operational amplifier U1 of the differential circuit 300 are connected with the pair of charge collection plates. When the charge collection plates discharge to the sampling resistor R1, the two input ends of the operational amplifier U1 can collect the potential difference between the pair of charge collection plates. The sampling voltage U O1 According to the virtual break and virtual short principles of the operational amplifier U1, the discharge current of the charge collection plate can be calculated. Further, according to the discharge time of the charge collection plate, the discharge current is integrated and operated, so as to calculate the charge amount of the pair of charge collection plates, and then the magnetic field strength of the permanent magnet can be determined according to the calculation that the magnetic field force and the coulomb force are equal when the free charges are in force balance.

[0048] In the above manner, after the charge collection plate completes the charge collection and calculates the magnetic field strength of the permanent magnet, the control charge generation module 100 continues to generate free charges, so as to recalculate the magnetic field strength of the permanent magnet. According to the actual situation, multiple data are collected, cross verification is performed between the multiple data, unreasonable data are excluded, and then the average value can be taken as the magnetic field strength of the permanent magnet at the current stage.

[0049] Therefore, the permanent magnet monitoring system provided by the utility model combines the charge generation module 100, the charge collection circuit 200 and the differential circuit 300, utilizes the deflection characteristics of the free charges in the magnetic field of the permanent magnet, monitors the change of the magnetic field strength of the permanent magnet in the use process, does not need to disassemble the permanent magnet, and does not need special detection instruments, so as to realize accurate and convenient monitoring of the aging condition of the permanent magnet.

[0050] Figure 2 The structure of the charge generation module and the charge collection circuit is shown, and in combination with Figure 1 and Figure 2 In some embodiments, the charge generation module 100 includes a high-voltage electrostatic generator 120, and the charge collection plate is arranged close to the electrode 120' of the high-voltage electrostatic generator 120.

[0051] The high-voltage electrostatic generator 120 is also referred to as an electrostatic generator. The high-voltage electrostatic generator 120 is capable of forming a high-voltage electrostatic field between the two electrodes 120', driving the electrodes 120' to ionize free electrons 110a, which are capable of moving to the first charge collection plate P1 arranged close to the north pole of the permanent magnet under the action of the magnetic field of the permanent magnet.

[0052] Figure 3 The structure of the differential circuit is shown, combined with Figure 1 and Figure 3 In some embodiments, the differential circuit 300 further comprises: a first current-limiting resistor R2 connected in series between the first charge collection plate P1 arranged close to the north pole of the permanent magnet and the inverting input terminal FL1 of the operational amplifier U1; a negative feedback resistor R3 connected between the output terminal and the inverting input terminal FL1 of the operational amplifier U1; a second current-limiting resistor R4 connected in series between the second charge collection plate P2 arranged close to the south pole of the permanent magnet and the non-inverting input terminal FL2 of the operational amplifier U1; and a pull-down resistor R5 connected to the non-inverting input terminal FL2 of the operational amplifier U1 and grounded.

[0053] The operational amplifier U1 and the first current-limiting resistor R2, the second current-limiting resistor R4, the negative feedback resistor R3 and the pull-down resistor R5 form the differential circuit 300 capable of accurately collecting the potential difference between a pair of charge collection plates. Based on the potential difference collected by the operational amplifier U1 and the output sampling voltage U O1 , the discharge current when the charge collection plate discharges can be accurately calculated.

[0054] Continuing to combine Figures 1 to 3 In some embodiments, the operational amplifier U1 satisfies:

[0055]

[0056] wherein U FL1 is the voltage of the first charge collection plate P1, obtained by the inverting input terminal FL1 of the operational amplifier U1, and U FL2 is the voltage of the second charge collection plate P2, obtained by the non-inverting input terminal FL2 of the operational amplifier U1. The output terminal of the operational amplifier U1 is connected to the controller, and the output sampling voltage U O1 output by the output terminal can be directly measured by the controller. According to the virtual open and virtual short principles of the operational amplifier U1, based on equation (1), the potential difference (U FL1 -U FL2 ) between the first charge collection plate P1 and the second charge collection plate P2 can be calculated.

[0057] Further, in some embodiments, R2=R3=R4=R5. Then, solving equation (1) gives U FL1 -U FL2= U O1 and U O1 = I1 x R1, so I1 = U O1 ÷ R1, where the resistance value of the sampling resistor R1 is known. Thus, the current flowing through the sampling resistor R1 can be directly calculated, and since the charge collection plate is connected in series with the sampling resistor R1, the discharge current of the charge collection plate is I1.

[0058] Continuing to refer to Figures 1 to 3 In some embodiments, the charge collection circuit 200 further has a switch K connected in series. By means of the switch K, the on-off of the charge collection circuit 200 can be conveniently controlled. When the charge collection circuit 200 needs to collect free charges, the switch K is opened; when the magnetic field force and the Coulomb force acting on the free charges are equal, the switch K is closed so that the charge collection plate discharges.

[0059] In some embodiments, the free charges are free electrons, and the charge collection circuit 200 has a charge collection state and a discharge state; in the charge collection state, the switch K is opened, and the free electrons move to the first charge collection plate P1 arranged close to the north pole of the permanent magnet; in the discharge state, the switch K is closed, and the pair of charge collection plates discharge.

[0060] In the charge collection state, the switch K is opened, and the high-voltage electrostatic generator 120 outputs high-voltage static electricity to ionize the free electrons 110a, which continuously move to the first charge collection plate P1 under the action of the magnetic field of the permanent magnet, so that the potential difference between the first charge collection plate P1 and the second charge collection plate P2 continuously increases. As the free electrons 110a continuously gather on the first charge collection plate P1, the first charge collection plate P1 continues to move the free electrons 110a to generate a same repulsion Coulomb force, which is opposite to the magnetic field force. When the magnetic field force and the Coulomb force acting on the free electrons 110a are equal in size, the free electrons 110a stop moving, the first charge collection plate P1 is saturated, and the potential difference between the first charge collection plate P1 and the second charge collection plate P2 reaches a maximum. Then, the high-voltage electrostatic generator 120 stops working, and at the same time, the switch K is closed, so that a closed loop is formed by the charge collection plate, the switch K and the sampling resistor R1, and the charge collection circuit 200 enters the discharge state, and the charge amount between the first charge collection plate P1 and the second charge collection plate P2 is slowly neutralized; since the charge collection plate is connected to the differential circuit 300, the change in the potential difference between the pair of charge collection plates can be monitored.

[0061] In some embodiments, when the first charge collection plate P1 is saturated, the force acting on the free electrons 110a satisfies:

[0062]

[0063] where q eLet be the charge of the free electron 110a, E represent the magnetic field strength of the permanent magnet, k be the Coulomb constant, Q be the charge of a pair of charge collection plates, and l be the distance between the ionization position of the free electron 110a and the first charge collection plate P1.

[0064] Wherein, the charge Q satisfies: t1 is the discharge start time of a pair of charge collection plates, and t2 is the discharge end time of a pair of charge collection plates.

[0065] During the discharge process of the charge acquisition plate, the potential difference decreases according to the RC discharge curve, and the potential difference change curve is as follows: Figure 4 As shown, the discharge time of the charge acquisition plate is between t1 and t2. During the discharge process of the charge acquisition plate, the discharge current I1 = U O1 ÷R1=f(t)÷R1, where f(t) is the potential difference detected at the output of operational amplifier U1 as a function of time t. Therefore, at the instant when the free electron 110a is in equilibrium, the charge Q of the pair of charge collection plates satisfies:

[0066]

[0067] Furthermore, when the first charge collection plate P1 is saturated, the magnetic force and Coulomb force on the free electron 110a reach equilibrium, meaning the force on the free electron 110a satisfies the above equation (2). Substituting equation (3) into equation (2), we can obtain:

[0068]

[0069] Thus, the parameter E, which characterizes the magnetic field strength of the permanent magnet, can be calculated.

[0070] Using the above method, after the charge acquisition board completes one charge acquisition and calculates the magnetic field strength of the permanent magnet, the polarity of the ionization voltage of the high-voltage electrostatic generator 120 is changed to recalculate the magnetic field strength of the permanent magnet. Multiple data acquisitions are performed based on actual conditions, and cross-validation is conducted between the data sets. After eliminating unreasonable data, the average value is taken as the magnetic field strength of the permanent magnet at the current stage.

[0071] This utility model embodiment also provides an electric power steering system, which is equipped with a permanent magnet monitoring system as described in any of the above embodiments, wherein the permanent magnet is mounted in the angle sensor of the electric power steering system.

[0072] The angle sensor is a core component in the input module of the electric power steering system, and its stability is crucial to the safe operation of the electric power steering system. At present, the sensing magnetic field in most angle sensors is provided by a permanent magnet. The permanent magnet is affected by the surrounding temperature and humidity during actual operation and will age to some extent, resulting in a decrease in magnetic field strength. The use of the above-mentioned permanent magnet monitoring system, which utilizes the directional deflection characteristics of free charges in the magnetic field of a permanent magnet, can monitor the gradual weakening of the magnetic induction strength during the aging process of the permanent magnet, predict the aging of the permanent magnet in a timely manner, and improve the safety of the electric power steering system.

[0073] Specifically, after each vehicle start, the controller can check whether the steering wheel position of the electric power steering system is in the neutral position during data initialization. If the steering wheel is in the neutral position, the controller can calculate the magnetic field strength of the permanent magnet of the angle sensor according to the above data acquisition and magnetic field strength detection calculation method. The permanent magnet of the angle sensor will age to varying degrees over time during operation in a complex temperature and humidity environment. The most direct manifestation of permanent magnet aging is a decrease in magnetic field strength. When the controller detects a decrease in the magnetic field strength of the permanent magnet, the controller can compensate for the difference in the magnetic flux signal output by the angle sensor during normal operation of the electric power steering system to ensure the accuracy of the angle signal output by the angle sensor.

[0074] Taking an angle sensor with three permanent magnets, including a first permanent magnet, a second permanent magnet, and a third permanent magnet, as an example. When the magnetic field strength of one permanent magnet (e.g., the first permanent magnet) is detected to be less than a set threshold, the controller can record the abnormality of the first permanent magnet and increase the detection frequency of the magnetic field strength of the first permanent magnet when the vehicle starts. In addition, the controller can increase the compensation value of the angle data output by the first permanent magnet; during cross-checking of the angle data, the angle data collected by the first permanent magnet can be used as a backup, and only when there is a large difference between the angle data collected by the second permanent magnet and the third permanent magnet, the angle data collected by the first permanent magnet is compared.

[0075] When the magnetic field strength of two permanent magnets (e.g., the first permanent magnet and the second permanent magnet) is detected to be less than a set threshold, the controller increases the compensation value of the angle data output by the first permanent magnet and the second permanent magnet, and cross-checks the angle data of the permanent magnet with the smaller degree of magnetic field degradation between the first permanent magnet and the second permanent magnet with the angle data of the third permanent magnet.

[0076] When the magnetic field strength of the three permanent magnets simultaneously appears less than the set threshold value, the controller increases the compensation value of the angle data output by the three permanent magnets. In addition, the controller starts to record the mileage of the vehicle thereafter. After the subsequent electric power steering system works for more than a certain safety mileage, the driver is prompted that the permanent magnet of the angle sensor of the electric power steering system is seriously aged and needs to be checked and replaced in time to avoid safety hazards. Among them, the safety mileage can be determined according to the magnetic field strength aging change rate tested in the early stage. After the driver handles the prompt, the controller recalculates the magnetic field strength of the permanent magnet of the angle sensor. If the magnetic field strength of the three permanent magnets is greater than the safety threshold value, the controller alarm is removed. If the driver refuses to handle the event, the electric power steering system does not provide assistance after the next vehicle ignition to ensure safety.

[0077] In this way, by assembling the permanent magnet monitoring system in the electric power steering system, the aging condition of the permanent magnet in the angle sensor of the electric power steering system can be monitored in real time, which has high precision and can timely warn the aging problem of the permanent magnet, and ensures the safety and reliability of the electric power steering system.

[0078] The permanent magnet monitoring system of the utility model can also be applied to other automobile part systems, can monitor the change of the magnetic field strength of the permanent magnet in use by the characteristics that free charges deflect in the magnetic field of the permanent magnet through the charge generation module 100, the charge collection circuit 200 and the differential circuit 300, does not need to disassemble the permanent magnet, and does not need special detection instrument, that is, the aging condition of the permanent magnet is accurately and conveniently monitored, and the safety and reliability of the system assembled with the permanent magnet are ensured.

[0079] The above content is a further detailed description of the utility model in combination with specific preferred embodiments, and cannot be determined that the specific implementation of the utility model is limited to these descriptions. For ordinary skilled persons in the technical field to which the utility model belongs, without departing from the concept of the utility model, a number of simple deductions or substitutions can be made, and all of them should be regarded as belonging to the protection scope of the utility model.

Claims

1. A permanent magnet monitoring system, characterized by, The application relates to a permanent magnet monitoring system. The application relates to a permanent magnet monitoring system. The application relates to a permanent magnet monitoring system. The application relates to a permanent magnet monitoring system.

2. The permanent magnet monitoring system of claim 1, wherein, The application relates to a permanent magnet monitoring system.

3. The permanent magnet monitoring system of claim 1, wherein, The application relates to a permanent magnet monitoring system. The application relates to a permanent magnet monitoring system. The application relates to a permanent magnet monitoring system. The application relates to a permanent magnet monitoring system. The application relates to a permanent magnet monitoring system.

4. The permanent magnet monitoring system of claim 3, wherein, The application relates to a permanent magnet monitoring system. wherein U FL1 is the voltage of the first charge collection plate, U FL2 is the voltage of the second charge collection plate, U O1 is the sampling voltage, R2 is the first current-limiting resistor, R3 is the negative feedback resistor, R4 is the second current-limiting resistor, and R5 is the pull-down resistor.

5. The permanent magnet monitoring system of claim 4, wherein, The application relates to a permanent magnet monitoring system.

6. The permanent magnet monitoring system of any one of claims 1-5, wherein, The application relates to a permanent magnet monitoring system.

7. The permanent magnet monitoring system of claim 6, wherein, The application relates to a permanent magnet monitoring system. The application relates to a permanent magnet monitoring system. The application relates to a permanent magnet monitoring system.

8. The permanent magnet monitoring system of claim 7, wherein, The application relates to a permanent magnet monitoring system. where q e is the charge of the free electron, E represents the magnetic field strength of the permanent magnet, k is the Coulomb constant, Q is the charge of a pair of the charge collection plates, and l is the distance between the ionization location of the free electron and the first charge collection plate. wherein the charge quantity Q satisfies: U O1 is the sampling voltage, R1 is the sampling resistance, t1 is the discharge start time of a pair of the charge collection plates, and t2 is the discharge end time of a pair of the charge collection plates.

9. An electric power assisted steering system characterised in that, The application relates to a permanent magnet monitoring system. The application relates to a permanent magnet monitoring system. The application relates to a permanent magnet monitoring system. The application relates to a permanent magnet monitoring system. The application relates to a permanent magnet monitoring system. The application relates to a permanent magnet monitoring system. The application relates to a permanent magnet monitoring system. The application relates to a permanent magnet monitoring system. The application relates to a permanent magnet monitoring system. The application relates to a permanent magnet monitoring system. The application relates to a permanent magnet monitoring system. The application relates to a permanent magnet monitoring system. The application relates to a permanent magnet monitoring system. The application relates to a permanent magnet monitoring system. 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