Multi-antipode magnetic encoder measuring system with programmable number of pole pairs

Abstract

The invention discloses a multi-antipode magnetic encoder measuring system with a programmable number of pole pairs, which comprises a shell, an electrical interface connector, a signal adapter plate, a magnetic signal generating element, a magnetic signal sensing element, a signal processing plate and a magnetic signal generating element positioning seat, and is characterized in that the electrical interface connector is connected with the signal adapter plate through a signal pin of the electrical interface connector; the signal adapter plate is connected with the signal processing plate through a signal pin, the signal processing plate is fixedly connected to the shell, the magnetic signal sensing element is connected to the signal processing plate in a welded mode, the magnetic signal sensing element and the magnetic signal generating element are parallel and opposite, the centers are aligned, and a fixed air gap is kept. When the magnetic signal generating element and the magnetic signal generating element positioning seat rotate along with a rotating mechanism of a client, an antipode magnetic signal is generated near a space where the magnetic signal sensing element is located, and the signal processing board realizes a multi-antipode digital output signal through a software algorithm.

Description

Technical Field

[0001] This invention relates to the field of encoder technology, and more specifically to a multi-pole magnetic encoder measurement system with programmable pole pair count. Background Technology

[0002] Based on the number of electrical cycles in one mechanical cycle, magnetic encoders can be divided into single-pole encoders and multi-pole encoders. A single-pole encoder typically consists of a magnetic sensor chip and a pair of magnets or magnetic rings. The magnetic sensor chip captures the periodic sine and cosine magnetic field signals generated by the magnets or magnetic rings that rotate synchronously with the rotating mechanism, and then calculates the absolute angle of the magnets or magnetic rings using an arctangent function. A multi-pole encoder typically consists of a magnetic sensor chip and multiple pairs of magnets or magnetic rings. When these multiple pairs of magnets or magnetic rings rotate with the motor shaft, the magnetic sensor chip captures multiple periodic sine and cosine magnetic field signals within one mechanical cycle, and then calculates the absolute electrical angle of the magnets or magnetic rings using an arctangent function. However, this type of multi-pole encoder places high demands on the magnetization and manufacturing processes of the multiple pairs of magnets or magnetic rings. Furthermore, this approach heavily relies on the number of pole pairs of the multiple pairs of magnets or magnetic rings; therefore, if application requirements change, the design and production of the multiple pairs of magnets or magnetic rings must be updated accordingly. These two factors increased the production cost of the multi-pole magnetic encoder project.

[0003] Therefore, there is an urgent need for a multi-pole magnetic encoder measurement system that does not rely on the number of magnet pole pairs or magnetic ring pole pairs, or whose number of magnet or magnetic ring pole pairs can be modified by software. By using a single pair of magnets and implementing a multi-pole magnetic encoder through software algorithms, it is possible to flexibly adapt to application scenarios with different numbers of pole pairs without changing the hardware structure. Summary of the Invention

[0004] The purpose of this invention is to propose a multi-pole magnetic encoder measurement system with programmable pole pair count to solve the problems of high requirements for the magnetization and processing technology of multi-pole magnets or multi-pole magnetic rings, and changes in the design and production process of multi-pole magnets or multi-pole magnetic rings when project requirements change, resulting in high production costs and slow R&D progress.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A programmable multi-pole magnetic encoder measurement system includes a housing, an electrical interface connector, a signal adapter board, a magnetic signal generating element, a magnetic signal sensing element, a signal processing board, and a magnetic signal generating element positioning seat. The electrical interface connector is connected to the signal adapter board via its built-in signal pins. The signal adapter board is connected to the signal processing board via signal pins. The signal processing board is fixedly connected to the housing. The magnetic signal sensing element is welded to the signal processing board and maintains a fixed position relative to the signal processing board. The magnetic signal sensing element and the magnetic signal generating element are parallel to each other, center-aligned, and maintain a fixed air gap. When the magnetic signal generating element and the magnetic signal generating element positioning seat rotate together with the rotating mechanism of the client, a pair of magnetic signals will be generated near the space where the magnetic signal sensing element is located. The signal processing board uses a software algorithm, namely, by converting the pair of magnetic signals into digital signals by an analog-to-digital converter (ADC) and then performing a modulus extraction algorithm, to realize a multi-pole digital output signal.

[0006] In some embodiments, the following technical features are also included: The aforementioned multi-pole magnetic encoder measurement system with programmable pole pair number has a magnetic signal generating element made of hard magnetic material, with the material composition being neodymium iron boron.

[0007] In some embodiments, the following technical features are also included: The aforementioned multi-pole magnetic encoder measurement system with programmable pole pair number uses Hall effect elements, AMR elements, TMR elements, and GMR elements as magnetic signal sensing elements.

[0008] In some embodiments, the following technical features are also included: The multi-pole magnetic encoder measurement system with programmable pole pairs has a signal processing board containing programmable digital devices such as microcontrollers (MCUs), digital signal processors (DSPs), and microprocessors (MPUs).

[0009] In some embodiments, the following technical features are also included: The multi-pole magnetic encoder measurement system with programmable pole pairs has a signal processing board containing devices with storage functions, such as independent Flash elements or programmable digital devices such as microcontrollers (MCUs), digital signal processors (DSPs), and microprocessors (MPUs) with built-in Flash.

[0010] In some embodiments, the following technical features are also included: A multi-pole magnetic encoder measurement system with programmable pole pair number, where a pair of pole magnetic signals represents the signal distribution within one mechanical cycle.

[0011] In some embodiments, the following technical features are also included: A multi-pole magnetic encoder measurement system with programmable pole pair number, using a modulus extraction algorithm in its software.

[0012] In some embodiments, the following technical features are also included: The multi-pole magnetic encoder measurement system with programmable pole pair number has a magnetic signal generating element consisting of a pair of pole magnets or a pair of pole magnetic rings, which are radially magnetized and embedded in the groove of the magnetic signal generating element positioning seat to maintain parallel and center alignment with the magnetic signal sensing element when rotating with the rotating mechanism.

[0013] In some embodiments, the following technical features are also included: A multi-pole magnetic encoder measurement system with programmable pole pairs includes a software algorithm comprising: calculating the maximum digital output value m of each pole pair after conversion based on a preset number of pole pairs p, where m = ((M + 1) / p) - 1, and M is the maximum digital output value of a pole pair; then applying a modulo operation to the real-time value angle_src of a pole pair output to obtain the real-time value angle_dst of the multi-pole output, where angle_dst = angle_src % (m + 1), and % is the modulo operator used to generate an electrical cycle signal that repeats p times within a mechanical cycle.

[0014] In some embodiments, the following technical features are also included: The multi-pole magnetic encoder measurement system with programmable pole pairs includes an analog-to-digital converter (ADC) module, an error correction module, a filter module, and an arctangent module on its signal processing board. The ADC module converts the analog electrical signal output from the magnetic signal sensing element into a digital quantity. The error correction module corrects the conversion error. The filter module performs filtering. The arctangent module calculates the digital angle. Then, the software algorithm is applied to perform multi-pole conversion, and the multi-pole digital quantity is output to the user terminal through the output interface.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The software-programmable multi-pole magnetic encoder proposed in this invention can use Hall elements, AMR elements, TMR elements, and GMR elements to achieve software output of multiple pairs of digital signals when there is only one pair of physical pole magnetic signals.

[0016] The software-programmable multi-pole magnetic encoder proposed in this invention can flexibly adapt to application requirements with different numbers of pole pairs without changing the magnetic signal generating element, magnetic signal sensing element, signal adapter board, and signal processing board.

[0017] Compared to traditional designs of multi-pole magnets, multi-pole magnetic rings, and multi-pole rotary transformers, this invention is low in cost and can be adapted efficiently and quickly when the required number of pole pairs changes.

[0018] The core benefit of this invention, achieved through the aforementioned hardware and software collaborative technical solution, lies in realizing the software programmability of the number of pole pairs in magnetic encoders. This top-level effect is specifically achieved through the synergistic effect of the following local effects: a) It reduces the dependence on high-precision multi-pole magnets, thereby reducing hardware costs and manufacturing difficulties; b) It enables the same hardware platform to quickly adapt to application requirements with different numbers of pole pairs through software configuration, greatly improving the product's flexibility and responsiveness. Attached Figure Description

[0019] Figure 1 This is a diagram of the external shape of a multi-pole magnetic encoder according to an embodiment of the present invention.

[0020] Figure 2 This is an exploded view of the multi-pole magnetic encoder structure according to an embodiment of the present invention.

[0021] Figure 3 This is a diagram showing the internal connection of a multi-pole magnetic encoder according to an embodiment of the present invention.

[0022] Figure 4 This is a diagram illustrating the signal flow in an embodiment of the present invention.

[0023] Figure 5 This is another signal flow diagram according to an embodiment of the present invention.

[0024] Figure 6 This is a flowchart of magnetic signal processing according to an embodiment of the present invention.

[0025] The reference numerals in the attached figures are explained as follows: 1. Housing; 2. Electrical interface connector; 21. Electrical interface connector inner plate; 22A. Electrical interface connector positioning post; 22B. Electrical interface connector positioning post; 22C. Electrical interface connector positioning post; 22D. Electrical interface connector positioning post; 3. Signal adapter board; 4. Signal processing board; 41A. Screw holes of signal processing board; 41B. Screw holes of signal processing board; 5. Magnetic signal generating element positioning seat; 6. Magnetic signal generating element; 7. Magnetic signal sensing element; 8A. Signal connection pin; 8B. Signal connection pin; 8C. Signal connection pin; 8D. Signal connection pin; 8E. Signal connection pin; 8F. Signal connection pin. Detailed Implementation

[0026] To clarify the technical problems, technical solutions, implementation processes, and performance demonstrations, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Various exemplary embodiments, features, and aspects of the present invention will be described in detail below with reference to the accompanying drawings. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0027] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0028] Furthermore, to better illustrate this disclosure, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this disclosure can be practiced without certain specific details. In some embodiments, methods, means, and algorithms well known to those skilled in the art are not described in detail in order to highlight the main points of this disclosure.

[0029] The present invention will be further illustrated by some specific examples below.

[0030] Example 1

[0031] This example illustrates a programmable multi-pole magnetic encoder, including a housing, an electrical interface connector, a signal adapter board, a magnetic signal generating element, a magnetic signal sensing element, and a signal processing board. The magnetic signal generating element and the magnetic signal sensing element are placed parallel to each other, center-aligned, and maintain a fixed air gap. The magnetic signal sensing element is soldered to the signal processing board, maintaining a relatively fixed position. When the magnetic signal generating element rotates with the rotating mechanism, it generates a changing magnetic signal near the magnetic signal sensing element. This magnetic signal corresponds to a sine signal and a cosine signal for one cycle within a mechanical cycle. The magnetic signal sensing element converts the magnetic sine and cosine signals into electrical sine and cosine signals, and decodes them into digital quantities through arctangent decoding. These digital quantities increase from zero to a maximum value within one mechanical cycle, representing a complete cycle of incremental change. The signal processing board reads the digital quantity and, through a software algorithm, specifically a modulo algorithm, transforms the digital quantity from one electrical cycle to multiple electrical cycles within a mechanical cycle, and outputs the digital quantity of the transformed electrical cycles, thereby achieving the output of multi-pole signals.

[0032] The magnetic signal generating element is a pair of pole magnets or a pair of pole magnetic rings, and its material composition is neodymium iron boron, and the magnetization direction is radial magnetization.

[0033] Magnetic signal sensing elements include Hall effect sensors, AMR sensors, TMR sensors, and GMR sensors. The magnetic signal sensing element can be selected as either analog or digital output as needed. If an analog output element is selected, the signal processing board needs to include a high-precision ADC module, an arctangent calculation module, etc., to convert the analog signal into a digital angle value. If an integrated digital output element is selected, it usually contains the relevant processing circuitry internally, and the signal processing board can directly read the digital angle value angle_src via a digital bus (such as SPI, I2C).

[0034] Signal processing components are programmable digital devices such as microcontrollers (MCUs), digital signal processors (DSPs), and microprocessors (MPUs).

[0035] like Figure 1 The diagram shows the external structure used in this embodiment, specifically the external structure after the multi-pole magnetic encoder electrical interface connector 2 protrudes from the connector holes of the multi-pole housing 1 from the inside out. It includes the product input voltage (DC 5V) and signal interface (RS485).

[0036] like Figure 2 As shown, the multi-pole magnetic encoder electrical interface connector 2 is connected to the signal adapter board 3 through its built-in signal pins. That is, the signal pins below the electrical interface connector are soldered to the plug-in holes on the signal adapter board. The signal adapter board 3 is connected to the signal processing board 4 through signal pins 8. That is, one end of the signal pin 8 is soldered to the plug-in hole on the signal adapter board, and the other end of the signal pin 8 is soldered to the plug-in hole on the signal processing board. The multi-pole magnetic encoder electrical interface connector 2 is connected to the positioning slots on the signal processing board through four positioning posts 22. The magnetic signal sensing element 7 is soldered to the center of the signal processing board 4 and is located below the signal processing board 4. The magnetic signal generating element 6 is parallel to the magnetic signal sensing element 7, aligned with the center, and maintains a fixed air gap. (As shown in Table 1, the magnetic field strength is at different distances perpendicular to the center surface of the magnetic signal generating element.) The magnetic signal generating element 6 is embedded in the groove at the center of the magnetic signal generating element positioning seat 5 and is connected to the magnetic signal generating element positioning seat 5 by liquid glue. The magnetic signal generating element positioning seat 5 is connected to the user's rotating mechanism by screws; this rotating mechanism is usually, but not limited to, a motor shaft. The signal generating element is first fixed to the positioning seat by tight fitting and bonding, and then together with it is fixed to the client's rotating mechanism (e.g., the motor shaft) by screws. When the client's rotating mechanism (e.g., the motor shaft) rotates, it will cause the magnetic signal generating element and the positioning seat to move synchronously. After the electrical interface connector 2, signal adapter board 3, and signal processing board 4 are integrated, they pass through the inside of the multi-pole magnetic encoder housing 1 to the outside and are fixed to the housing 1 through the screw holes 41 on the signal processing board 4. The fixed air gap needs to be determined based on the magnetic field strength characteristics of the selected magnetic signal generating element and the optimal operating range of the magnetic signal sensing element. Taking the XX model Hall element used in this embodiment as an example, its ideal linear measurement range is approximately YY mT to ZZ mT. Therefore, the air gap should be set so that the magnetic field strength on the surface of the magnetic sensing element falls within this range. As shown in Table 1, when the air gap is between 3.2 mm and 3.7 mm, the magnetic field strength is 60.9 mT to 53.1 mT, which meets the requirements.

[0037] Table 1

[0038] like Figure 4 As shown, firstly, the number of pole pairs required for software implementation is determined based on project requirements, denoted as p. Only after this number of pole pairs is determined can the corresponding parameters be set in the software algorithm. Then, the maximum digital output of a single pole encoder before conversion is set to (2^n – 1) = M, which is the digital signal quantity induced by the magnetic signal sensing element under the action of the pair of magnetic signal generating elements before enabling the pole pair programmable algorithm, read and output by the signal processing board. The maximum digital output of each pole pair of the multi-pole magnetic encoder after conversion is set to (((M + 1) / p) - 1) = m, which is the digital signal quantity induced by the magnetic signal sensing element under the action of the pair of magnetic signal generating elements after enabling the pole pair programmable algorithm, read and output by the signal processing board. Simultaneously, the real-time value of the digital output of a single pole encoder before conversion is set to angle_src, meaning that angle_src changes from 0 to M within one mechanical cycle. In other words, angle_src corresponds to one electrical cycle within one mechanical cycle. Therefore, the real-time value of the digital output of the multi-pole magnetic encoder after conversion is (angle_src). %(m+1))=angle_dst, meaning that angle_dst changes from 0 to m within one mechanical cycle. In other words, angle_dst corresponds to multiple electrical cycles within one mechanical cycle, specifically p electrical cycles in this case. (The % operator here is a computer science operator, also known as the modulo operator. This operator divides the operand before the operator by the operand after the operator and calculates the remainder, which is the final result of the expression.)

[0039] It should be noted that the angular resolution of the multi-pole output signal simulated by the software algorithm in this solution within a single cycle depends on the resolution of the original single-pole signal and the set number of pole pairs p, which is floor((M+1) / p) or ceil((M+1) / p). This resolution is typically lower than the resolution achievable with a comparable sensor using physical multi-pole magnets. The core advantage of this solution lies in the programmability of the number of pole pairs and low cost, rather than ultimate accuracy.

[0040] like Figure 5 As shown, to illustrate the effectiveness of this method, an example is given here: a pair of pole magnetic encoders originally outputs a 17-bit digital angle. Now, a software algorithm is needed to output a digital signal of 28 pole pairs. That is, before enabling the programmable pole pair algorithm, the signal sensed by the magnetic signal sensing element under the action of the pair of pole magnetic signal generating elements is read and output as a digital signal by the signal processing board. This digital signal changes from 0 to 131071 within one mechanical cycle, corresponding to an angle range of 0–360° (this range is the mechanical cycle). The range of variation (also the range of electrical cycle variation) is determined by enabling the pole pair programmable algorithm. The signal sensed by the magnetic signal sensing element under the action of the pair of pole magnetic signal generating elements is read and output as a digital signal by the signal processing board. This digital signal changes within one mechanical cycle from 0 to 4680, repeating this process 28 times. The corresponding angle range is 0–360° (this range represents the electrical cycle of each pair of poles under 28 pole pairs). Therefore, the real-time value of the digital output of the multi-pole magnetic encoder is (the real-time value of the digital output of a pair of pole magnetic encoders % (4680 + 1)). For example... Figure 6 As shown, the magnetic signal sensing element detects the magnetic signal generated by the magnetic signal generating element in the space where the magnetic signal sensing element is located. It is converted into an analog voltage signal by a dedicated circuit, then converted into a digital quantity by an analog-to-digital converter (ADC) module, and then converted into a digital quantity by error correction, filtering, and arctangent conversion. The signal processing board communicates with the magnetic signal sensing element through the SPI interface and reads the digital quantity representing the angular characteristics of the magnetic signal in the magnetic signal sensing element. The signal processing board then performs lookup table nonlinear calibration and lookup table temperature drift calibration on the read digital quantity. Finally, it performs software multi-pole conversion to obtain multi-pole digital quantity, which is output to the user terminal through the output interface.

[0041] Example 2

[0042] This embodiment, based on Embodiment 1, focuses on solving the problem of temperature drift. To this end, a temperature resistor is added to the signal processing board to measure the temperature around the signal processing board. By collecting the errors at different temperature steps within the operating temperature range, a temperature error compensation table is established, and this table is used to correct the angle value for temperature during product use.

[0043] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-pole magnetic encoder measurement system with programmable pole pair count, comprising a housing, an electrical interface connector, a signal adapter board, a magnetic signal generating element, a magnetic signal sensing element, a signal processing board, and a magnetic signal generating element positioning seat. The electrical interface connector is connected to the signal adapter board via its built-in signal pins. The signal adapter board is connected to the signal processing board via signal pins. The signal processing board is fixedly connected to the housing. The magnetic signal sensing element is welded to the signal processing board and maintains a fixed position relative to the signal processing board. The magnetic signal sensing element and the magnetic signal generating element are parallel to each other, center-aligned, and maintain a fixed air gap. When the magnetic signal generating element and the magnetic signal generating element positioning seat rotate together with the rotating mechanism of the client, a pair of magnetic signals will be generated near the space where the magnetic signal sensing element is located. The signal processing board uses a software algorithm, namely, by converting the pair of magnetic signals corresponding to the pair of electrical signals of the pair of poles through an analog-to-digital converter (ADC) and then performing a modulus extraction algorithm, to realize a multi-pole digital output signal.

2. The multi-pole magnetic encoder measurement system with programmable pole pair count according to claim 1, characterized in that, The magnetic signal generating element is made of hard magnetic material, and the material composition is neodymium iron boron.

3. The multi-pole magnetic encoder measurement system with programmable pole pair count according to claim 1, characterized in that, The magnetic signal sensing element is a Hall element, an AMR element, a TMR element, or a GMR element.

4. The multi-pole magnetic encoder measurement system with programmable pole pair count according to claim 1, characterized in that, The signal processing board includes programmable digital devices such as microcontrollers (MCUs), digital signal processors (DSPs), and microprocessors (MPUs).

5. The multi-pole magnetic encoder measurement system with programmable pole pair count according to claim 1, characterized in that, The signal processing board includes devices with storage functions, such as independent Flash elements or programmable digital devices such as microcontrollers (MCUs), digital signal processors (DSPs), and microprocessors (MPUs) with built-in Flash.

6. The multi-pole magnetic encoder measurement system with programmable pole pair count according to claim 1, characterized in that, The pair of magnetic pole signals are the signal distribution within one mechanical cycle.

7. The multi-pole magnetic encoder measurement system with programmable pole pair count according to claim 1, characterized in that, The software algorithm described is a modulo algorithm.

8. The multi-pole magnetic encoder measurement system with programmable pole pair number according to claim 1, characterized in that, The magnetic signal generating element is a pair of pole magnets or a pair of pole magnetic rings, radially magnetized, and embedded in the groove of the magnetic signal generating element positioning seat, so as to maintain parallel and center alignment with the magnetic signal sensing element when rotating with the rotating mechanism.

9. The multi-pole magnetic encoder measurement system with programmable pole pair count according to claim 1 or 7, characterized in that, The software algorithm includes: calculating the maximum digital output value m of each pair of poles after conversion based on a preset number of pole pairs p, where m = ((M + 1) / p) - 1, and M is the maximum digital output value of a pair of poles; then applying a modulo operation to the real-time value angle_src of a pair of pole output values ​​to obtain the real-time value angle_dst of multiple pairs of pole output values, where angle_dst = angle_src % (m + 1), and % is the modulo operator used to generate an electrical cycle signal that repeats p times within a mechanical cycle.

10. The multi-pole magnetic encoder measurement system with programmable pole pair count according to claim 1, characterized in that, The signal processing board also includes an analog-to-digital converter (ADC) module, an error correction module, a filter module, and an arctangent module. The ADC module converts the analog electrical signal output by the magnetic signal sensing element into a digital quantity. The error correction module corrects the conversion error. The filter module performs filtering. The arctangent module calculates the digital angle. Then, the software algorithm is applied to perform multi-pole conversion, and the multi-pole digital quantity is output to the user terminal through the output interface.

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