Magnetic drive device and position detection method

Abstract

This application discloses a magnetic drive device and a position detection method, relating to the field of position detection technology. The magnetic drive device includes a transport guide rail, on which a stator assembly and multiple movers are mounted. The multiple movers move along the transport guide rail. The stator assembly is formed by splicing multiple stator modules. The stator assembly and the multiple movers are electromagnetically coupled to detect the position of the movers. Each stator module includes a stator circuit board, on which multiple excitation coils and multiple induction coils are mounted. The stator circuit board also includes an excitation circuit. The stator circuit board has a control unit configured to: determine the target excitation frequency of the excitation circuit based on the number of movers that the stator module can carry, so that when the movers move relative to the stator assembly, each induction coil outputs an induction signal that changes with the position of the mover; the control unit is also configured to: determine the position information of each mover based on the induction signal. This addresses the technical problem that large changes in signal bias during signal processing affect the detection accuracy and stability.

Description

Technical Field

[0001] This application relates to the field of position detection technology, and in particular to a magnetic drive device and a position detection method. Background Technology

[0002] Inductive encoders have advantages such as compact structure, strong environmental adaptability, and high reliability, and are suitable for high-precision position feedback sensing in magnetic drive conveyor systems.

[0003] In a magnetic drive system with multiple moving heads operating simultaneously, eddy currents are generated in the moving head conductors within the alternating magnetic field. This alters the effective magnetic field strength and flux linkage of the excitation coil, leading to a change in the equivalent inductance of the excitation coil. This inductance change causes a shift in the resonant point of the excitation circuit and a change in the excitation current, which in turn causes fluctuations in the induced voltage of the induction coil in the edge region. Ultimately, this manifests as a dynamic DC bias after signal conditioning. This bias changes dynamically with the number and position of the moving heads and cannot be eliminated by traditional one-time power-on correction. It easily causes fluctuations in system speed measurement, decreased accuracy in stator splicing position calculation, and even misjudgment of moving head position, affecting the detection performance and operational stability of the magnetic drive system.

[0004] Therefore, there is an urgent need for a position detection scheme that can effectively solve the bias interference in order to improve the detection accuracy of the system. Summary of the Invention

[0005] The main objective of this application is to provide a magnetic drive device and a position detection method, which aims to solve the technical problem of how to reduce the impact of the induction signal bias on the position detection accuracy of multiple movers when they are detected simultaneously.

[0006] This application provides a magnetic drive device, including a transport rail, on which a stator assembly and multiple movers are provided. The multiple movers move relative to the stator assembly along the transport rail. The stator assembly is formed by splicing multiple stator modules. The stator assembly and the multiple movers are electromagnetically coupled to detect the position of the movers. The stator module includes a stator circuit board, on which multiple excitation coils and multiple induction coils are provided, and the stator circuit board also includes an excitation circuit; The stator circuit board is equipped with a control unit, which is configured to: determine the target excitation frequency of the excitation circuit according to the number of movers that the stator module can carry, so that when the movers move relative to the stator assembly, each induction coil outputs an induction signal that changes with the position of the movers; The control unit is also configured to determine the position information of each of the moving parts based on the sensing signal.

[0007] In one embodiment, the control unit determines the target excitation frequency of the excitation circuit based on the number of movers that the stator module can support, including: The control unit determines the target number of movers based on the number of movers that can be carried on the stator module, and determines the target excitation frequency based on the preset correspondence between the target number of movers and the excitation frequency, so as to output an excitation signal corresponding to the target excitation frequency to the excitation coil.

[0008] In one embodiment, the control unit is configured to determine the target number of movers in the following manner: When the number of movers that the stator module can support is an even number a, the control unit determines that the target number of movers is a / 2. When the number of movers that the stator module can carry is an odd number b, the control unit determines that the target number of movers is (b+1) / 2 or (b-1) / 2.

[0009] In one embodiment, before determining the target excitation frequency, the excitation circuit adjusts the initial excitation frequency of the stator module to a preset anti-mixing excitation frequency.

[0010] In one embodiment, the excitation circuit adjusts the anti-mixing excitation frequencies of adjacent stator modules to be different.

[0011] In one embodiment, the excitation circuit adjusts the anti-mixing excitation frequencies of the spaced stator modules to be the same.

[0012] In one embodiment, the stator circuit board further includes a post-processing circuit, which includes a demodulation circuit, a filtering and amplification circuit, and an analog-to-digital conversion circuit. The input terminal of the demodulation circuit is connected to the output terminal of the excitation circuit, and the input terminal of the demodulation circuit is also connected to the induction coil; the input terminal of the filter amplification circuit is connected to the output terminal of the demodulation circuit, and the output terminal of the filter amplification circuit is connected to the input terminal of the analog-to-digital conversion circuit; the output terminal of the analog-to-digital conversion circuit is connected to the input terminal of the control unit. The demodulation circuit is used to demodulate the induction signal output by the induction coil. The filtering and amplification circuit filters and amplifies the demodulated induction signal and then performs analog-to-digital conversion through the analog-to-digital conversion circuit, so that the control unit determines the position information of each mover based on the processed induction signal.

[0013] In one embodiment, the control unit is configured to determine the number of movers that the stator module can carry based on the length of the stator module.

[0014] This application also proposes a position detection method for the aforementioned magnetic drive device, the position detection method comprising: The target excitation frequency of the excitation circuit is determined based on the number of movers that the stator module can support, so that when the movers move relative to the stator assembly, each induction coil outputs an induction signal that changes with the position of the movers. The position information of each mover is determined based on the induction signal.

[0015] In one embodiment, determining the target excitation frequency of the excitation circuit based on the number of movers that the stator module can support includes: The target number of movers is determined based on the number of movers that can be carried on the stator module, and the target excitation frequency is determined based on the preset correspondence between the target number of movers and the excitation frequency, so as to output an excitation signal corresponding to the target excitation frequency to the excitation coil.

[0016] In one embodiment, determining the target number of movers based on the number of movers that the stator module can support includes: Determine the number of movers that the stator module can support; When the number of movers that the stator module can support is an even number 'a', the target number of movers is determined to be 'a / 2'. When the number of movers that the stator module can support is an odd number b, the target number of movers is determined to be (b+1) / 2 or (b-1) / 2.

[0017] In one embodiment, prior to the step of determining the target excitation frequency, the excitation circuit adjusts the initial excitation frequency of the stator module to a preset anti-mixing excitation frequency.

[0018] In one embodiment, the excitation circuit adjusts the anti-mixing excitation frequencies of adjacent stator modules to be different.

[0019] In one embodiment, the excitation circuit adjusts the anti-mixing excitation frequencies of the spaced stator modules to be the same.

[0020] In one embodiment, the control unit is configured to determine the number of movers that the stator module can carry based on the length of the stator module.

[0021] The magnetic drive device and its position detection method proposed in this application have at least the following technical effects: This magnetic drive device can adaptively adjust the target excitation frequency of the excitation circuit according to the number of movers that a single stator module can carry, thereby compensating for the change in equivalent inductance of the excitation coil caused by the eddy current effect of the movers, so that the excitation circuit always maintains a better working state, and effectively suppresses the dynamic DC bias caused by the uneven magnetic field and inductance offset of the edge induction coil. This reduces the bias drift of the induction signal under the condition of simultaneous detection of multiple movers, reduces speed measurement fluctuations, improves the calculation accuracy of the stator splicing position, avoids misjudgment of the mover position, improves the stability and system reliability of position detection in long stator segment splicing and multi-motor synchronous operation, and broadens the application range of inductive encoders in multi-motor magnetic drive conveying scenarios. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of one embodiment of the stator module and the mover of this application; Figure 2 This is a second schematic diagram of an embodiment of the stator module and the mover of this application; Figure 3 This is a schematic diagram illustrating the effect of the mover on the inductance of the excitation coil in this application; Figure 4 This is a schematic diagram of an embodiment of the present application that optimizes the bias of the edge coil; Figure 5 This is a schematic diagram showing the before and after optimization of the bias of the edge coil in this application; Figure 6 This is a diagram showing the relationship between back electromotive force and phase current in this application; Figure 7 This is a flowchart illustrating an embodiment of the mover position detection method of this application; Figure 8 This is a detailed flowchart of an embodiment of step S100 of this application.

[0024] Explanation of icon numbers: 100. Stator module; 101. Stator circuit board; 102. Post-processing circuit; 110. Excitation coil; 111. Microstepping excitation coil; 112. Coarse-stepping excitation coil; 120. Induction coil; 1211. Sine microstepping coil; 1212. Cosine microstepping coil; 1221. Sine coarse-stepping coil; 1222. Coarse-stepping coil; 130. Excitation circuit; 140. Control unit; 150. Demodulation circuit; 160. Filtering and amplification circuit; 170. Analog-to-digital converter circuit; 200, Moving element; 210, Coarse partition; 220, Subdivided partition.

[0025] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0026] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0027] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0028] Position sensors and other position measurement devices are widely used in industrial automation, automotive, aerospace, and other fields. Position sensing applications encompass various sensing elements, such as optical position sensors, inductive position sensors, and anisotropic magnetoresistive sensors. Optical position sensors offer high resolution, high accuracy, and fast response, but suffer from poor environmental adaptability, being sensitive to mechanical vibration, shock, and temperature changes, and unsuitable for harsh environments such as those with moisture, dust, or oil contamination. Magnetoresistive sensors, designed based on the anisotropic magnetoresistive effect, have low installation requirements, strong environmental adaptability, and low cost, but are susceptible to external magnetic field interference, and generally exhibit lower resolution and accuracy. Optical and magnetoresistive sensing methods struggle to simultaneously meet the complex application requirements of high precision, high resolution, and strong environmental adaptability.

[0029] Position detection devices based on the eddy current effect, such as inductive position sensors, overcome the shortcomings of other position sensors to some extent. Furthermore, their printed circuit board design makes them easy to integrate, install, and cost-effective.

[0030] In the embodiments of this application, the inductive position sensor can be applied to a magnetic drive device, which includes, but is not limited to, magnetic drive units such as linear motors, multi-stator rotary motors, and motion platforms. The magnetic drive device includes a transport guide rail, on which a stator assembly and multiple movers 200 are mounted. The multiple movers 200 move relative to the stator assembly along the transport guide rail. The stator assembly is formed by splicing multiple stator modules 100, and the stator assembly electromagnetically engages with the multiple movers 200 to detect the position of the movers 200. Figure 1As shown, the stator module 100 includes a stator circuit board 101, on which a plurality of excitation coils 110 and a plurality of induction coils 120 are provided. The stator circuit board 101 is also provided with an information processing circuit. In a specific embodiment, the information processing circuit includes an excitation circuit 130, a demodulation circuit 150, a filter amplification circuit 160, an analog-to-digital conversion circuit 170, and a control unit 140.

[0031] In one specific embodiment, the mover 200 also includes a mover circuit board with a copper-plated area. Movement of the mover 200 alters the magnetic circuit between the excitation coil 110 and the induction coil 120. When the magnetic circuit changes, the induction coil 120 outputs a corresponding changing induction signal. This induction signal can also be used to adjust the excitation signal output to the excitation coil 110, thereby achieving accurate detection of the mover's position. For example, the excitation coil can be located on the outer side, and the induction coil can be located on the inner side and surrounded by the excitation coil.

[0032] In one specific embodiment, such as Figure 2 As shown, the excitation coil 110 is continuously wound with N turns of inductor coil, divided into a fine division excitation coil 111 and a coarse division excitation coil 112. The two sets of excitation coils are arranged symmetrically vertically. The fine division excitation coil 11 contains a set of sinusoidal fine division induction coils 1211 and 1212 wound in opposite directions. The sinusoidal fine division induction coils 1211 and 1212 are distributed on two wiring layers of the PCB and connected by vias to prevent short circuits. The coarse division excitation coil also contains a set of sine and cosine coarse division induction coils 1221 and 1222 wound in opposite directions. The coarse division induction coil is used to initially locate the mover at a certain position of the fine division induction coil. It does not have high precision requirements, and the number of coil cycles is less than that of the fine division induction coil, but the winding method is the same. The mover 200 also includes a PCB printed circuit board, which is divided into a fine division copper pour area 210 and a coarse division copper pour area 220.

[0033] The signal processing circuit includes an excitation circuit 130 and a subsequent processing circuit 102. In the excitation circuit 130, an alternating current of a certain frequency is supplied to the excitation coil 110, generating a magnetic field H1 with the same frequency as the current. When there is no mover, theoretically, the magnetic fields inside the forward and reverse wound induction coils cancel each other out, so the output voltage at the induction coil port is 0. When the mover assembly moves relative to the stator assembly, eddy currents are generated inside the copper-plated area of ​​the mover, thus generating a new magnetic field H2 opposite in direction to the original magnetic field H1. This changes the alternating magnetic flux passing through the induction coil 120, causing a corresponding induced voltage to be output at the induction coil port. The magnitude of the induced voltage is related to the area covered by the mover plate. The induced voltage signal is then demodulated by the subsequent demodulation circuit 140 to obtain a useful low-frequency signal. Next, the signal amplitude is increased to the maximum range that the analog-to-digital converter circuit can process by the filter and amplification circuit 160. Subsequently, the analog-to-digital converter circuit 150 converts it into a digital signal, and finally, the control unit 140 performs displacement calculations to obtain the position of the mover 200.

[0034] The stator module 100 achieves non-contact measurement through the mutual inductance between the excitation coil 110 and the induction coil 120. Compared with optical position sensors, magnetoresistive sensors, or other traditional position sensors, inductive position sensors have the advantages of compact structure, strong environmental adaptability, and high reliability. Furthermore, they can be directly used for high-precision position feedback sensing in drive control systems such as magnetic drive devices, or applied to servo control systems to replace traditional encoder products. Secondly, since its detection part is an inductive coil, the peripheral circuit can use general-purpose chips, regardless of chip type, exhibiting high versatility and compatibility, suitable for different application scenarios, and effectively reducing chip requirements.

[0035] Specifically, when the mover 200 moves relative to the stator assembly, the relative coupling area and magnetic flux of the corresponding induction coil change in real time. According to the law of electromagnetic induction, the change in magnetic flux generates an induced voltage. As the mover position changes, the amplitude and phase of the induced signal output by the induction coil 120 change accordingly, thus outputting a changing induced signal. Therefore, the changing induced signal output by the induction coil 120, which can directly reflect the mover position, provides a reliable data basis for the control unit 140 to calculate the mover position information, enabling the control unit 140 to determine the position of each mover based on the induced signal. For example, the control unit can extract the effective signal from the induced signal to retain the alternating signal related to displacement, and perform position calculation based on the obtained effective signal to determine the position information of each mover.

[0036] Understandably, when the stator assembly is not covered, the induction coils in the edge region are susceptible to the influence of the radial magnetic field at the edge, causing the internal magnetic fields of the sine and cosine induction coils wound in opposite directions to not be completely canceled out. When the stator assembly is working, the induction coils in the edge region will output a high-frequency induction component with the same frequency as the excitation signal. This component is conditioned by the subsequent circuitry and manifests as a DC bias. This initial bias can be eliminated by power-on correction.

[0037] However, as Figure 3 As shown, in a multi-motor magnetic drive system, under simultaneous detection of multiple movers, eddy currents are generated in the conductors of the mover assembly above the excitation coil in an alternating magnetic field. These eddy currents alter the effective magnetic field strength and flux linkage within the excitation coil, directly changing its equivalent inductance. This change in equivalent inductance leads to a resonant point shift, altering the excitation current and causing a synchronous change in the induced voltage of the edge region's induction coil. Therefore, the DC bias of the edge coil dynamically changes with the influence of the movers. This bias is not a fixed value but dynamically varies with the number and position of the movers, and traditional one-time power-on calibration cannot eliminate this dynamic error. In multi-motor detection scenarios, this fundamental dynamic bias has several adverse effects: increased speed measurement fluctuations, reduced accuracy in stator splicing position calculations, and even misjudgment of mover position. As the number of mover plates within the stator segment increases, the equivalent inductance of the excitation coil continuously changes, and the bias of the edge coil also exhibits a monotonically changing trend, further degrading the system's detection performance. Inductive position sensors are used in multi-movement magnetic drive systems. Signal bias issues during signal processing can affect detection accuracy and stability, leading to errors in mover position detection.

[0038] To effectively address the impact of signal bias on the accuracy of mover position detection, embodiments of this application propose a magnetic drive device and a position detection method. The control device includes a controller and a control module with control functions. For ease of description, embodiments of this application primarily focus on control devices such as control units, controllers, and control modules with control functions as the executing entities. The control unit can be, but is not limited to, a microcontroller (MCU), a programmable logic controller (PLC), a digital signal processor (DSP), or a field-programmable gate array (FPGA).

[0039] In this embodiment of the application, the control unit 140 is configured to: determine the target excitation frequency of the excitation circuit 130 according to the number of movers that the stator module can carry, so that when the mover 200 moves relative to the stator assembly, each induction coil outputs an induction signal that changes with the position of the mover; The control unit 140 is also configured to determine the position information of each of the moving parts based on the sensing signals.

[0040] The number of movers that the stator module 100 can support can be determined based on the size and structure of the stator module, specifically based on its length, such as its length in the direction of mover movement. The control unit 140 can further determine the target excitation frequency corresponding to the excitation circuit 130 based on a preset mapping relationship between the number of movers that the stator module 100 can support and the excitation frequency. Then, the excitation circuit 130's signal generator generates an excitation signal (alternating electrical signal) that is at the same frequency as or corresponds to the target excitation frequency, and outputs the generated excitation signal to each excitation coil of the stator module. When the excitation signal is applied to the excitation coil, the excitation coil generates an alternating magnetic field of the same frequency.

[0041] In the embodiments of this application, the control unit 140 determines the target excitation frequency of the excitation circuit 130 based on the number of movers that the stator module 100 can support, thereby compensating for the change in equivalent inductance of the excitation coil caused by the eddy current effect of the movers, ensuring that the excitation circuit always maintains an optimal operating state, and effectively suppressing the dynamic DC bias caused by uneven magnetic field and inductance offset of the edge induction coil. This reduces the bias drift of the induction signal under simultaneous multi-motor detection conditions, reduces speed measurement fluctuations, improves the calculation accuracy of the stator splicing position, avoids misjudgment of mover position, and enhances the stability and reliability of position detection during long stator segment splicing and simultaneous multi-motor operation.

[0042] In one specific embodiment, the control unit 140 is configured to determine the number of movers that the stator module 100 can carry based on the length of the stator module 100. For example, the number of movers that the stator module 100 can carry can be determined to be one, two, three, or more, based on the length of the stator module 100. In the embodiments of this application, the correspondence between the number of movers that the stator module 100 can carry and the excitation frequency can be preset. The number of movers that the stator module 100 can carry is determined based on the length of the stator module 100. The movers can adopt a flat plate structure, and their surfaces can be divided into multiple different functional areas, forming a precise spatial matching relationship with the coil array on the stator module. By changing the electromagnetic coupling state between different areas of the mover and the coils, the magnetic drive device can identify the position of the mover 200 in real time. In this way, the magnetic drive device can have good scalability, and can be flexibly adapted to conveyor rails of different lengths by adding or removing stator modules 100; and each stator module 100 can independently complete signal acquisition and processing, which to a certain extent avoids signal interference caused by long-distance wiring, thus providing a reliable physical basis for solving the bias problem.

[0043] As an example, the control unit 140 determines the target excitation frequency of the excitation circuit 130 based on the number of movers that the stator module 100 can carry, including: the control unit 140 determines the target number of movers based on the number of movers that the stator module 100 can carry, and determines the target excitation frequency based on the preset correspondence between the target number of movers and the excitation frequency, so as to output an excitation signal corresponding to the target excitation frequency to the excitation coil 110.

[0044] Understandably, the correspondence between the number of movers that the stator module 100 can carry and the excitation frequency can be preset, resulting in a theoretical excitation frequency that can be designed without the intervention of movers 200. When multiple mover 200 position detection is performed, the intervention of movers 200 will cause the actual natural frequency to deviate from the theoretical excitation frequency. If the drive is still performed at the theoretical frequency, the output signal of the edge coil will exhibit a large DC bias drift. Therefore, the excitation frequency needs to be corrected. To this end, a target number of movers is introduced. Based on the target number of movers, the control unit 140 recalculates the equivalent excitation frequency that takes into account the influence of movers 200 using a preset correspondence, and outputs an excitation signal corresponding to the target excitation frequency to the excitation coil 110, thereby offsetting part of the bias change.

[0045] In one embodiment, the stator circuit board 101 further includes a post-processing circuit 102, which includes a demodulation circuit 150, a filter amplifier circuit 160, and an analog-to-digital converter circuit 170. The input terminal of the demodulation circuit 150 is connected to the output terminal of the excitation circuit 130, and the input terminal of the demodulation circuit 150 is also connected to the induction coil 120. The input terminal of the filter amplifier circuit 160 is connected to the output terminal of the demodulation circuit 150, and the output terminal of the filter amplifier circuit 160 is connected to the input terminal of the analog-to-digital converter circuit 170. The output terminal of the analog-to-digital converter circuit 170 is connected to the input terminal of the control unit 140.

[0046] The demodulation circuit 150 is used to demodulate the induction signal output by the induction coil 120. The filter and amplification circuit 160 filters and amplifies the demodulated induction signal and then performs analog-to-digital conversion through the analog-to-digital conversion circuit 170, so that the control unit 140 determines the position information of each mover 200 based on the processed induction signal.

[0047] Understandably, the excitation circuit 130 is used to generate a stable high-frequency excitation signal (AC signal). Its input is connected to the control unit 140. It can generate and output an excitation signal containing the target excitation frequency according to the instructions of the control unit 140 (such as an excitation square wave), and output the generated excitation signal to the excitation coil 110 of the stator module 100. The filter amplifier circuit 160 includes a filter circuit and an amplifier circuit, which can filter and amplify the signal: the filter circuit (such as a low-pass filter) filters out high-frequency interference components in the induced signal and retains the effective signal directly corresponding to the mover position; the amplifier circuit amplifies the extracted effective signal to the effective range of the analog-to-digital converter circuit 170. The analog-to-digital converter circuit 170 is used to convert the filtered and amplified analog voltage signal into a digital signal. The FPGA control unit and other control units 140 are used to perform displacement calculation based on the digital signal after analog-to-digital conversion to obtain the position information of each mover 200.

[0048] Compared with position detection schemes in related technologies, the embodiments of this application have advantages such as low cost and strong resistance to environmental interference. At the same time, when detecting the position of multiple movers, it can effectively improve the mutual inductance crosstalk between stator modules and the offset change at the splicing point. To a certain extent, it can reduce the speed fluctuation of the magnetic drive device and the applicable measurement system, and improve the calculation accuracy at the splicing point of the stator module.

[0049] In related technologies, the excitation frequency is determined directly by the number of movers carried by the stator module. For example, the excitation frequency is determined by the even number a of movers that can be carried on the stator module. The bias change of the edge coil is measured. The bias value changes from X(0) to X(a). The bias will change a at most a times, and there are cases where the bias change is large.

[0050] like Figure 4 , Figure 5 As shown, in one embodiment of this application, the control unit 140 is configured to determine the target number of movers in the following manner: When the number of movers that the stator module 100 can support is an even number a, the control unit 140 determines that the target number of movers corresponding to the number of movers that can be supported is a / 2. When the number of movers that the stator module 100 can carry is an odd number b, the control unit 140 determines the target number of movers corresponding to the number of movers that can be carried to be (b+1) / 2 or (b-1) / 2.

[0051] In the embodiments of this application, the control unit 140 determines the target number of movers based on the number of movers that can be carried on the stator module 100, and further determines the corresponding target excitation frequency based on the preset correspondence between the target number of movers and the excitation frequency, so as to output an excitation signal with the corresponding target excitation frequency to the excitation coil 110. Figure 4As shown, the stator module has a mover cover. Figure 4 Point A is used to indicate the edge coil (induction coil) of the stator module. When the edge coil is not covered by a moving part, the edge induction coil is biased. For example... Figure 5 As shown, before optimization, the edge coil bias changes as follows: initial bias X(0) without a mover, bias X(1) with one mover in the stator module, bias X(a / 2) with a / 2 movers in the stator module, bias X(a-1) with a-1 movers in the stator module, and bias X(a) with a movers in the stator module. In other words, before optimization, the edge coil bias changes from X(a) to X(0). After optimization, the edge coil bias changes as follows: initial bias X(0) without a mover, bias X(1) with one mover in the stator module, bias X(a / 2) with a / 2 movers in the stator module, bias X(a-1) with a-1 movers in the stator module, and bias X(a) with a movers in the stator module. After using the method of this application, the edge coil bias changes from X(a / 2) to X(0). Using the optimization method of this application, the bias change is significantly reduced compared to before optimization. Understandably, optimization refers to adjusting the excitation signal using the method in the embodiments of this application: the control unit 140 determines the target number of movers based on the number of movers that can be carried on the stator module 100, and determines the target excitation frequency based on the preset correspondence between the target number of movers and the excitation frequency, so as to output an excitation signal corresponding to the target excitation frequency to the excitation coil 110.

[0052] For example, the optimization method includes: when the control unit determines that the number of movers that can be carried on the stator module 100 is an even number 'a', it determines that the target number of movers corresponding to the number of movers that can be carried is 'a / 2'. Based on the assumption that there are 'a / 2' movers above the stator module 100, the target excitation frequency of the excitation circuit 130 is designed. The bias change can be suppressed to 'a / 2', reducing the bias change by half compared to before optimization. Taking a stator module 100 that can carry 4 movers as an example, when designing the excitation frequency with 4 movers, if each mover independently causes a fluctuation, the bias change before optimization is at most 4 times; after optimization, the bias change is at most 2 times, reducing the number of bias changes from 4 to 2 times.

[0053] When the number of movers that can be carried on the stator module 100 is an odd number of b, the target number of movers corresponding to the number of movers that can be carried is determined to be (b+1) / 2 or (b-1) / 2. Based on the assumption that there are (b+1) / 2 or (b-1) / 2 movers above the stator module 100, the target excitation frequency of the excitation circuit 130 is designed, and the bias change can be suppressed to (b+1) / 2 times. Taking a stator module 100 that can carry 5 movers as an example, when designing the excitation frequency with 5 movers, if each mover independently causes a fluctuation, the bias change before optimization is at most 5 times; after optimization, the bias change can be suppressed to 3 times, reducing the number of bias changes from 5 times to 3 times.

[0054] In this way, the number of movers that can be carried can be converted into the target number of movers to design the actual excitation frequency, thereby suppressing the fluctuation of the induction signal bias. This can be used in multi-motor position detection to reduce the edge coil bias change, reduce the impact of large signal bias changes on detection accuracy and stability, and further reduce the mover position detection error.

[0055] like Figure 6 As shown, in multi-stable position detection, there are multiple stator modules 100, which are sequentially assembled. The stator modules 100 on the stator assembly can be assembled indefinitely. Due to the precision limitations of the crystal oscillator, the excitation frequencies of different stator modules will differ (e.g., ...). Figure 6 The excitation signals 1 and 2 have different frequencies, ranging from a few hertz to several hundred hertz. Mutual inductance crosstalk occurs between the excitation coils of adjacent stator modules, causing frequency mixing and generating beat frequency interference signals (the difference frequency of adjacent stator modules is modulated onto the excitation frequency). These difference frequency signals are modulated onto the inductance signal, thus generating mutual inductance crosstalk. Furthermore, because these difference frequency signals are smaller than the envelope of the useful signal, they cannot be filtered out by subsequent demodulation and filtering circuits.

[0056] To address the mixing problem, in one specific embodiment, before determining the target excitation frequency, the excitation circuit first adjusts the initial excitation frequency of the stator module to a preset anti-mixing excitation frequency.

[0057] In one specific embodiment, the excitation circuit adjusts the anti-mixing excitation frequencies of adjacent stator modules to be different.

[0058] In other words, the excitation circuit uses frequency offset excitation to stagger the excitation frequencies between adjacent stators, for example, by more than 20kHz. This shifts the low-frequency errors caused by the crystal oscillator's frequency accuracy to a higher frequency range above kHz. When the mover assembly moves, the induced signal output by the induction coil will contain these frequency offset components. Through frequency offset excitation, it can ensure, to a certain extent, that the subsequent demodulation and filtering circuits can effectively filter out interference. Mutual inductance beat frequency is a low-frequency interference phenomenon that occurs when the excitation signal frequencies between adjacent stator modules are similar. The active frequency offset adjustment strategy can suppress beat frequency interference at its source by increasing the excitation frequency difference between adjacent stator modules.

[0059] In a specific embodiment, the frequency misalignment adjustment method is as follows: based on the resonant circuit characteristics formed by the stator module and the starting capacitor, the excitation frequency of adjacent stator modules is adjusted by adjusting the capacitance value of the starting capacitor corresponding to the stator module.

[0060] Understandably, using an LC resonant circuit, the excitation coil of each stator module 100 and its matching starting capacitor form a parallel or series resonant circuit. By adjusting the capacitance C of the circuit, its resonant frequency can be precisely fine-tuned, thus causing the actual operating frequencies of different stator modules 100 to be offset from each other. After frequency offset adjustment, the invalid signals generated by mutual inductance crosstalk in the output signals of the induction coils of adjacent stator modules 100 are migrated to the high-frequency band, forming a significant frequency difference with the valid signals carrying position information. In subsequent signal processing, these high-frequency invalid signals can be effectively filtered out by a filtering circuit.

[0061] In some alternative embodiments, the excitation circuit may also have the same anti-mixing excitation frequency for the stator modules 100 spaced apart.

[0062] In the embodiments of this application, the excitation circuit 130 can design the anti-mixing excitation frequencies of adjacent stator modules to be different, while the anti-mixing excitation frequencies of spaced stator modules can be designed to be the same. The control unit 140 outputs corresponding anti-mixing excitation signals to the excitation coils of each stator module, so that when the mover moves relative to the stator assembly, each induction coil outputs an induction signal that changes with the position of the mover. The control unit 140 then determines the position information of each mover based on the induction signals. Understandably, having the same anti-mixing excitation frequency for spaced stator modules 100 can also reduce the complexity of frequency misalignment adjustment and facilitate practical applications. For example, if a stator assembly is composed of N (N is an odd number) stator modules, then the anti-mixing excitation frequencies for modules 1, 3, 5, ..., N are designed to be the same; the anti-mixing excitation frequencies for modules 2, 4, 6, ..., N-1 are designed to be the same; while the anti-mixing excitation frequencies for modules 1 and 2, 2 and 3, 3 and 4, 4 and 5, 5 and 6, and N and N-1 are designed to be different. In this design, the entire stator assembly only needs to be set with two anti-mixing excitation frequencies. This design can reduce the complexity of frequency misalignment adjustment and facilitate practical applications.

[0063] To solve the mixing problem, this solution adopts a frequency misalignment adjustment strategy before determining the target excitation frequency. Specifically, the excitation circuit 130 adjusts the excitation frequencies of two adjacent stator modules to be different. In the induction signals output by the induction coils of adjacent stator modules 100, the invalid signals generated by mutual inductance crosstalk are migrated to the high-frequency band, forming a significant frequency difference with the valid signals carrying position information.

[0064] like Figure 1 , Figure 2 , Figure 5 , Figure 7 As shown, the embodiments of this application provide a position detection method. The position detection method is applied to the magnetic drive device as described in the above embodiments. The specific structure of the magnetic drive device is as described in the above embodiments. Since this position detection method adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0065] For example, in an embodiment of this application, the location detection method includes: Step S100: Determine the target excitation frequency of the excitation circuit based on the number of movers that the stator module can carry, so that when the movers move relative to the stator assembly, each induction coil outputs an induction signal that changes with the position of the movers. Step S200: Determine the position information of each mover based on the sensing signal.

[0066] In one embodiment, determining the target excitation frequency of the excitation circuit based on the number of movers that the stator module can support in step S100 includes: The target number of movers is determined based on the number of movers that can be carried on the stator module, and the target excitation frequency is determined based on the preset correspondence between the target number of movers and the excitation frequency, so as to output an excitation signal corresponding to the target excitation frequency to the excitation coil.

[0067] In this embodiment, the control unit 140 determines the target excitation frequency of the excitation circuit 130 based on the number of movers that the stator module 100 can support. This compensates for the change in the equivalent inductance of the excitation coil caused by the eddy current effect of the movers, ensuring that the excitation circuit always maintains an optimal operating state and effectively suppressing the dynamic DC bias caused by uneven magnetic field and inductance offset of the edge induction coil. This reduces the bias drift of the induction signal under simultaneous multi-motor detection conditions, lowers speed measurement fluctuations, improves the accuracy of stator splicing position calculation, avoids misjudgment of mover position, and enhances the stability and reliability of position detection during long stator segment splicing and simultaneous multi-motor operation.

[0068] Understandably, the correspondence between the number of movers that the stator module 100 can carry and the excitation frequency can be preset. The resulting excitation frequency is a theoretical value, which can be designed without the intervention of movers 200. When performing multi-motor 200 position detection, the intervention of movers 200 will cause the actual natural frequency to deviate from the theoretical excitation frequency. If driven at the theoretical frequency, the output signal of the edge coil will exhibit a large DC bias drift. Therefore, the excitation frequency needs to be corrected. To this end, a target number of movers is introduced. Based on the target number of movers, the equivalent excitation frequency considering the influence of movers 200 is recalculated using a preset correspondence as the target excitation frequency, so as to output an excitation signal corresponding to the target excitation frequency to the excitation coil 110, thereby offsetting part of the bias change.

[0069] like Figure 5 , Figure 8 As shown, in one embodiment, determining the target number of movers based on the number of movers that the stator module can carry in step S100 includes: Step S110: Determine the number of movers that the stator module can support; Step S120: When the number of movers that the stator module can carry is an even number a, determine the target number of movers corresponding to the number of movers that can be carried as a / 2; when the number of movers that the stator module can carry is an odd number b, determine the target number of movers corresponding to the number of movers that can be carried as (b+1) / 2 or (b-1) / 2.

[0070] The target number of movers is determined based on the number of movers that can be carried on the stator module 100, and the corresponding target excitation frequency is further determined based on the preset correspondence between the target number of movers and the excitation frequency, so as to output an excitation signal of the corresponding target excitation frequency to the excitation coil 110. Figure 4As shown, the stator module has a mover cover. Figure 4 Point A is used to indicate the edge coil (dynamic coil) of the stator module. When the edge coil is not covered by a moving element, the signal of the edge coil is biased. For example... Figure 5 As shown, before optimization, the edge coil bias changes as follows: initial bias X(0) without a mover, bias X(1) for one mover in the stator module, bias X(a / 2) for a / 2 movers in the stator module, bias X(a-1) for a-1 movers in the stator segment module, and bias X(a) for a movers in the stator module. Before optimization, the edge coil bias changes to X(a)-X(0). After optimization, the edge coil bias changes as follows: initial bias X(0) without a mover, bias X(1) for one mover in the stator module, bias X(a / 2) for a / 2 movers in the stator module, bias X(a-1) for a-1 movers in the stator module, and bias X(a) for a movers in the stator module. After optimization, the edge coil bias changes to X(a / 2)-X(0).

[0071] In this way, the number of borne movers can be converted into a smaller number of target movers to design the target excitation frequency, thereby suppressing the fluctuation of the induction signal bias. This can be used in multi-motor position detection to reduce the edge coil bias change, reduce the impact of large signal bias changes on detection accuracy and stability, and further reduce mover position detection error.

[0072] To solve the mixing problem, this solution employs a frequency misalignment adjustment strategy in the excitation circuit before determining the target excitation frequency.

[0073] Specifically, before determining the target excitation frequency, the excitation circuit adjusts the initial excitation frequency of the stator module to a preset anti-mixing excitation frequency.

[0074] Specifically, the excitation circuit adjusts the preset anti-mixing excitation frequency by making the anti-mixing excitation frequencies of adjacent stator modules different, preferably by making the anti-mixing excitation frequencies of spaced stator modules the same.

[0075] In other words, the excitation circuit uses frequency offset excitation to stagger the excitation frequencies between adjacent stators, for example, by more than 20kHz. This shifts the low-frequency errors caused by the crystal oscillator's frequency accuracy to a higher frequency range above kHz. When the mover assembly moves, the induced signal output by the induction coil will contain these frequency offset components. Through frequency offset excitation, it can ensure, to a certain extent, that the subsequent demodulation and filtering circuits can effectively filter out interference. Mutual inductance beat frequency is a low-frequency interference phenomenon that occurs when the excitation signal frequencies between adjacent stator modules are similar. The active frequency offset adjustment strategy can suppress beat frequency interference at its source by increasing the excitation frequency difference between adjacent stator modules.

[0076] The above description is only a part of the embodiments of this application and does not limit the patent scope of this application. All equivalent structural transformations made under the technical concept of this application and using the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included in the patent protection scope of this application.

Claims

1. A magnetic drive device, comprising a conveying guide rail, on which a stator assembly and a plurality of movers are disposed, the plurality of movers moving relative to the stator assembly along the conveying guide rail, the stator assembly being formed by splicing together a plurality of stator modules, the stator assembly electromagnetically engaging with the plurality of movers to detect the position of the movers; characterized in that: The stator module includes a stator circuit board, on which multiple excitation coils and multiple induction coils are provided, and the stator circuit board also includes an excitation circuit; The stator circuit board is equipped with a control unit, which is configured to: determine the target excitation frequency of the excitation circuit according to the number of movers that the stator module can carry, so that when the movers move relative to the stator assembly, each induction coil outputs an induction signal that changes with the position of the movers; The control unit is also configured to determine the position information of each of the moving parts based on the sensing signal.

2. The magnetic drive device according to claim 1, characterized in that, The control unit determines the target excitation frequency of the excitation circuit based on the number of movers that the stator module can support, including: The control unit determines the target number of movers based on the number of movers that can be carried on the stator module, and determines the target excitation frequency based on the preset correspondence between the target number of movers and the excitation frequency, so as to output an excitation signal corresponding to the target excitation frequency to the excitation coil.

3. The magnetic drive device according to claim 2, characterized in that, The control unit is configured to determine the target number of movers in the following manner: When the number of movers that the stator module can support is an even number a, the control unit determines that the target number of movers is a / 2. When the number of movers that the stator module can carry is an odd number b, the control unit determines that the target number of movers is (b+1) / 2 or (b-1) / 2.

4. The magnetic drive device according to claim 1, characterized in that, Before determining the target excitation frequency, the excitation circuit adjusts the initial excitation frequency of the stator module to a preset anti-mixing excitation frequency.

5. The magnetic drive device according to claim 4, characterized in that, The excitation circuit adjusts the anti-mixing excitation frequencies of adjacent stator modules to be different.

6. The magnetic drive device according to claim 4, characterized in that, The excitation circuit adjusts the anti-mixing excitation frequency of the stator modules at intervals to be the same.

7. The magnetic drive device according to claim 1, characterized in that, The stator circuit board also includes a post-processing circuit, which includes a demodulation circuit, a filtering and amplification circuit, and an analog-to-digital conversion circuit. The input terminal of the demodulation circuit is connected to the output terminal of the excitation circuit, and the input terminal of the demodulation circuit is also connected to the induction coil; the input terminal of the filter amplification circuit is connected to the output terminal of the demodulation circuit, and the output terminal of the filter amplification circuit is connected to the input terminal of the analog-to-digital conversion circuit; the output terminal of the analog-to-digital conversion circuit is connected to the input terminal of the control unit. The demodulation circuit is used to demodulate the induction signal output by the induction coil. The filtering and amplification circuit filters and amplifies the demodulated induction signal and then performs analog-to-digital conversion through the analog-to-digital conversion circuit, so that the control unit determines the position information of each mover based on the processed induction signal.

8. The magnetic drive device according to any one of claims 1 to 7, characterized in that, The control unit is configured to determine the number of movers that the stator module can carry based on the length of the stator module.

9. A position detection method, characterized in that, The position detection method, applied to the magnetic drive device as described in any one of claims 1 to 8, comprises: The target excitation frequency of the excitation circuit is determined based on the number of movers that the stator module can support, so that when the movers move relative to the stator assembly, each induction coil outputs an induction signal that changes with the position of the movers. The position information of each mover is determined based on the induction signal.

10. The position detection method as described in claim 9, characterized in that, The determination of the target excitation frequency of the excitation circuit based on the number of movers that the stator module can support includes: The target number of movers is determined based on the number of movers that can be carried on the stator module, and the target excitation frequency is determined based on the preset correspondence between the target number of movers and the excitation frequency, so as to output an excitation signal corresponding to the target excitation frequency to the excitation coil.

11. The position detection method as described in claim 10, characterized in that, Determining the target number of movers based on the number of movers that the stator module can support includes: Determine the number of movers that the stator module can support; When the number of movers that the stator module can support is an even number 'a', the target number of movers is determined to be 'a / 2'. When the number of movers that the stator module can support is an odd number b, the target number of movers is determined to be (b+1) / 2 or (b-1) / 2.

12. The position detection method according to claim 9, characterized in that, Before determining the target excitation frequency, the excitation circuit adjusts the initial excitation frequency of the stator module to a preset anti-mixing excitation frequency.

13. The position detection method according to claim 12, characterized in that, The excitation circuit adjusts the anti-mixing excitation frequencies of adjacent stator modules to be different.

14. The position detection method according to claim 12, characterized in that, The excitation circuit adjusts the anti-mixing excitation frequency of the stator modules at intervals to be the same.

15. The position detection method according to claim 9, characterized in that, The control unit is configured to determine the number of movers that the stator module can carry based on the length of the stator module.

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