Motor rotation angle detecting device
By installing an external multi-pole magnetic ring and encoder on the outside of the motor in a lateral mounting manner, the problems of magnetic field interference and space constraints when installing encoders inside the motor are solved, and motor angle detection with higher accuracy and anti-interference capability is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- QUANZHOU KTSENSE MICROELECTRONICS CO LTD
- Filing Date
- 2025-07-24
- Publication Date
- 2026-07-24
Smart Images
Figure CN224555398U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to motor operating position detection technology, and in particular belongs to the field of motor control and sensor technology. Background Technology
[0002] Currently, motor encoders are typically installed inside the motor or at the opposite end of the shaft. This traditional installation method has several drawbacks. Several common drawbacks are listed below.
[0003] Magnetic field interference: Strong electromagnetic fields inside the motor can interfere with the normal operation of the encoder, leading to unstable feedback signals. This is especially true when the encoder is close to the motor stator or rotor, as the magnetic field and current generated during motor operation can affect the magnetic sensing element.
[0004] Limited installation space: Integrating an encoder inside a motor is subject to space constraints. The space available for installing the encoder and magnet inside the motor is very limited, the installation process is cumbersome, and aligning the encoder with the rotor is difficult. This space constraint can easily introduce mechanical installation errors, causing deviations in encoder readings.
[0005] Large reading error: In traditional solutions, the encoder's output accuracy is affected by factors such as uneven magnetic field distribution and mechanical assembly tolerances. In addition, changes in the electromagnetic environment (such as fluctuations in nearby current) may also introduce additional noise and errors.
[0006] In summary, existing motor rotor position detection solutions still have room for improvement in terms of anti-interference capability and measurement accuracy, and a new solution is urgently needed to overcome the above-mentioned shortcomings. Utility Model Content
[0007] In order to obtain accurate motor operating angle information, this application provides a motor operating angle detection device.
[0008] The device includes an external multipole magnetic ring and an encoder; The external multipole magnetic ring is fixed on the motor shaft and located outside the motor. Its number of pole pairs is the same as that of the internal multipole magnetic ring of the motor. The external multipole magnetic ring rotates synchronously with the shaft. An encoder is disposed outside the motor housing, adjacent to the side or outer peripheral surface of the external multipole magnetic ring, and the sensing surface is perpendicular to the axis of rotation. The encoder is used to detect the magnetic field of the external multipole magnetic ring and output an angle signal. A gap is left between the encoder and the external multipole magnetic ring.
[0009] Optionally, the encoder is a magnetoresistive encoder or a Hall array encoder.
[0010] Optionally, the external multipole magnetic ring is fixed to the end of the rotating shaft.
[0011] Optionally, the external multipole magnetic ring can be fixed by interference fit, bonding, or mechanical clamping.
[0012] Optionally, the gap between the encoder and the external magnetic ring is 1 to 3 mm.
[0013] Optionally, the encoder is fixed to the overall housing of the motor.
[0014] Optionally, the number of pole pairs of the external magnetic ring is the same as the number of pole pairs of the motor rotor.
[0015] Optionally, the encoder outputs a signal in the form of a PWM signal, an ABZ incremental encoded signal, or an absolute value SSI / SPI output signal.
[0016] Optionally, the size and magnetic properties of the external multipole magnetic ring can be optimized according to the detection requirements, so that the encoder always operates within a good magnetic field range.
[0017] By adopting the technical solution of this application, the internal electromagnetic interference of the motor is isolated by an external magnetic ring, and the assembly accuracy requirements are reduced by lateral installation, which significantly improves the accuracy of angle detection, anti-interference ability and installation convenience. Attached Figure Description
[0018] Figure 1(a) is a side view of a motor system according to an embodiment of the present invention; Figure 1(b) is a front view schematic diagram of a motor system applying an embodiment of the present invention. Detailed Implementation
[0019] The specific embodiments and examples of this utility model are described below with reference to the accompanying drawings. Those skilled in the art should understand that the embodiments described herein are only for explaining this utility model and should not be construed as limiting this application.
[0020] See Figure 1(a). Figure 1(a) is a side view of a motor system according to an embodiment of the present invention. As shown in Figure 1(a), the motor system 101 includes a motor 102, an outer cover 103, a rotating shaft 108, and other parts. The outer cover 103 is used to cover the motor 102 and other components of the motor system 101, providing protection against dust and oil, and preventing debris from falling into the motor system.
[0021] The motor 102 includes a stator (not shown in the figure) and a rotor (not shown in the figure). The rotor is the rotating part of the motor 102, and it is usually composed of a rotor core, rotor windings, and a shaft 108, and is generally installed inside the motor. The stator is the stationary part of the motor 102, and it is usually composed of a stator core, stator windings, and a frame, and is generally installed outside the rotor. There is a certain air gap between the stator and the rotor.
[0022] The shaft 108 refers to the shaft in a motor responsible for transmitting power and torque; it is one of the most important components of the motor. The function of the shaft is to transmit the motor's power to the load, causing it to move. By connecting the motor and the load, the motor shaft enables energy transfer and control between them. The shaft can extend outside the motor, facilitating the mounting of an external multi-pole magnetic ring on the shaft.
[0023] One of the rotor and stator of motor 102 includes a built-in permanent magnet (not shown in the figure). This built-in permanent magnet is used to generate a magnetic field, causing the coils in the other rotor or stator to rotate in the magnetic field. This built-in permanent magnet is typically a multipole pair magnetic ring.
[0024] The encoder can be an optical encoder, which requires the use of a grating or similar device for measurement. In this embodiment, the encoder can be a magnetic encoder. In the prior art, to control the correct operation of the motor 102, an encoder needs to be placed on the rotor or stator of the motor, and another permanent magnet for measurement needs to be placed on the other side of the rotor or stator to obtain the relative rotation information between the rotor and stator. This relative rotation information is then transmitted to the motor controller to control the operation of the motor 102. However, due to the complex internal magnetic field of the motor 102, this solution requires sophisticated magnetic immunity design and signal correction design, increasing the complexity of the encoder system design. Moreover, the narrow air gap between the rotor and stator of the motor 102 makes alignment between the encoder and the permanent magnet difficult, also resulting in a decrease in measurement accuracy.
[0025] According to an embodiment of this utility model, an external multipole magnetic ring 104 is installed on the portion of the motor shaft 108 that extends outside the motor 102, thereby rotating synchronously with the shaft 108. The external multipole magnetic ring 104 can be firmly fixed to the shaft 108 by means of interference fit, bonding, or mechanical clamping to avoid slippage.
[0026] An encoder 105 is disposed near the external multipole magnetic ring 104, and the magnetic encoder sensor 105 is fixed to a component of the motor system 101. The encoder 105 may be disposed near the side of the external multipole magnetic ring 104, as shown in positions 105 and 106, or it may be disposed near the outer peripheral surface of the external multipole magnetic ring 104, as shown in position 107.
[0027] Regardless of its position among positions 105-107, the sensing surface of the magnetic encoder sensor 105 is perpendicular to the axis of the rotating shaft 108. The "sensing surface" refers to the sensitive surface of the sensor (such as a Hall element, magnetoresistive element, etc.) in the encoder. This surface must be parallel to the side of the magnetic ring to accurately capture changes in the magnetic field.
[0028] In this way, a relative rotation is formed between the external multipole magnetic ring 104 and the encoder 105, and this relative rotation is consistent with the relative rotation between the motor rotor and stator. Therefore, by measuring the relative rotation information between the external multipole magnetic ring 104 and the encoder 105, it can be used to equivalently represent the relative rotation between the motor rotor and stator, thereby controlling the operation of the motor 102.
[0029] In the above configuration, the external multipole magnetic ring 104 and encoder 105 are placed outside the motor 102, resulting in significantly less magnetic field interference compared to that experienced inside the motor 102. This greatly reduces the complexity requirements of the encoder system. The relatively large external space of the motor 102 also facilitates accurate alignment of the relative positions of the external multipole magnetic ring 104 and encoder 105.
[0030] In terms of installation, the encoder 105 and the external multipole magnetic ring 104 are positioned laterally (off-axis), meaning the encoder 105 is not required to be at the center of the shaft and does not occupy space at the opposite end of the shaft. This significantly reduces the coaxiality requirements of the encoder and magnetic ring during assembly, minimizing the impact of mechanical installation errors on the signal and improving angle detection accuracy. Furthermore, because the encoder is not located on the extended line of the motor shaft, axial leakage flux and electromagnetic noise have less impact on it, significantly improving the system's anti-interference capability. Additionally, lateral (off-axis) installation means the encoder's sensing surface is perpendicular to the shaft axis, detecting the radial component of the annular magnetic field.
[0031] A certain gap should be maintained between the encoder 105 and the external multipole magnetic ring 104, but this gap should not be too large. Empirically, a gap of 1 to 3 millimeters is appropriate.
[0032] The encoder 105 can be mounted on the housing 103 or the overall housing 109 of the motor 102. The encoder sensor can be mounted on the overall housing 109 via a mechanical structure such as a bracket, or, if the motor housing 103 is made of a non-magnetic material and the distance between the magnet and the housing is within the sensor's sensing range, it can be fixed to the motor housing. The bracket can be a strip-shaped, fan-shaped, or other shaped bracket extending from the motor housing 103. These methods can easily achieve a gap of 1–3 mm between the encoder 105 and the external multipole magnetic ring 104.
[0033] The number of pole pairs of the external multipole magnetic ring 104 can be the same as that of the multipole magnetic ring built into the motor. Advantages include, but are not limited to, that the rotor's mechanical angle is naturally synchronized with the angle output by the magnetic encoder, allowing the encoder signal to be directly used for field-oriented control (FOC) or commutation logic, eliminating the pole pair conversion step, reducing algorithm complexity, decreasing the computational load in signal processing, and improving system real-time performance. The outermost part of the overall casing 109 is the outermost part of the entire device, which protects the entire device from dust and oil.
[0034] See Figure 1(b). Figure 1(b) is a front view of an embodiment of the present invention. Figure 1(b) shows the magnetic field distribution of the magnetic ring, with the N / S poles alternating as indicated. The number of pole pairs of the external multi-pole magnetic ring is the same as the number of pole pairs of the internal multi-pole magnetic ring in the motor.
[0035] The number of pole pairs of the external multipole magnetic ring is the same as that of the internal multipole magnetic ring of the motor. This means that the external multipole magnetic ring generates the same magnetic field as the internal multipole magnetic ring of the motor. After the encoder senses the magnetic field, it outputs a signal. At this time, the motor running angle can be obtained by analyzing the output signal. Even if the output signal is not a standard sine signal, it will not affect the subsequent output signal for motor control.
[0036] The encoder mentioned in the embodiments may be replaced by other terms in practice, including but not limited to magnetic encoders, optical encoders, etc. Magnetic encoders may also be called magnetic encoders, sensors, magnetic sensors, angle sensors, etc. Those skilled in the art will understand that these terms all refer to encoders with the same function, and all such encoders should be covered within the protection scope of this application.
[0037] The above embodiments are only used to provide a detailed description of the technical solutions of this application. However, the description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application, and should not be construed as a limitation of this application. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the protection scope of this application.
Claims
1. A motor rotation angle detection device, wherein the motor contains a built-in multi-pole magnetic ring, characterized in that, include: An external multipole magnetic ring is fixed on the motor shaft and located outside the motor. Its number of pole pairs is the same as that of the internal multipole magnetic ring of the motor. The external multipole magnetic ring rotates synchronously with the shaft. An encoder is disposed outside the motor, adjacent to the side or outer peripheral surface of the external multipole magnetic ring, and the sensing surface is perpendicular to the axis of rotation. The encoder is used to detect the magnetic field of the external multipole magnetic ring and output an angle signal. A gap is left between the encoder and the external multipole magnetic ring.
2. The motor rotation angle detection device according to claim 1, characterized in that: The encoder includes a magnetoresistive encoder or a Hall array encoder.
3. The motor rotation angle detection device according to claim 1, characterized in that: The external multipole magnetic ring is fixed to the end of the rotating shaft.
4. The motor rotation angle detection device according to claim 1, characterized in that: The external multipole magnetic ring can be fixed by interference fit, bonding or mechanical clamping.
5. The motor rotation angle detection device according to claim 1, characterized in that: The gap between the encoder and the external magnetic ring is 1 to 3 millimeters.
6. The motor rotation angle detection device according to claim 1, characterized in that: The encoder is fixed to the overall housing of the motor.
7. The motor rotation angle detection device according to claim 1, characterized in that: The number of pole pairs of the external magnetic ring is the same as the number of pole pairs of the motor rotor.
8. The motor rotation angle detection device according to claim 1, characterized in that: The encoder outputs a signal in one of the following forms: PWM signal, ABZ incremental encoding signal, or absolute value SSI / SPI output signal.
9. The motor rotation angle detection device according to claim 1, characterized in that: The size and magnetic properties of the external multipole magnetic ring can be optimized according to the detection needs, so that the encoder always works within a good magnetic field range.