Inductance encoder for rotary motor
By combining a non-contact inductive encoder with a dual-channel sensing chip, the shortcomings of optical encoders and magnetic encoders in terms of environmental adaptability and reliability are solved, achieving high-precision position detection and signal stability in complex environments, and reducing system complexity and cost.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-13
- Publication Date
- 2026-03-31
AI Technical Summary
Existing optical encoders and magnetic encoders are inadequate in terms of environmental adaptability, cost, and reliability, making it difficult to provide stable and reliable position signals under complex working conditions.
A non-contact inductive encoder is adopted, which utilizes the principle of electromagnetic induction, combined with a dual-channel inductive sensor chip and an optimized decoding algorithm to realize the detection and processing of sine and cosine signals. This avoids environmental pollution and magnetic field interference, simplifies the structure, and improves decoding accuracy and anti-interference ability.
It improves the environmental adaptability and reliability of the encoder, reduces manufacturing costs, enhances mechanical stability and signal stability, and meets the requirements of high-precision motor control.
Smart Images
Figure CN224066086U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model belongs to encoder technical field, concretely relates to a kind of inductance encoder for rotary motor. BACKGROUND
[0002] As the core power unit in the field of industrial automation, robot, electric vehicle, etc., the accurate detection of the position and speed of rotary motor is the key to realize high-precision motion control. As the core component of motor feedback system, encoder needs to provide stable and reliable position signal under complex working conditions. The current mainstream encoder technology includes grating encoder and magnetic grating encoder, which realizes position detection based on different physical principles.
[0003] At present, grating encoder and magnetic grating encoder are widely used in specific scenarios, but their environmental adaptability, cost and reliability problems are increasingly prominent. For example, grating encoder has the following shortcomings: (1) poor environmental adaptability, dust, oil stains or water vapor can easily contaminate grating disc or optical elements, resulting in signal distortion; (2) complex structure, high difficulty in processing of precision optical components, high manufacturing cost; (3) weak anti-vibration ability, mechanical vibration can easily cause the offset of grating disc and sensor, affecting the signal stability; for example, magnetic grating encoder has the following shortcomings: (1) resolution is limited by the distance between magnetic poles, it is difficult to detect small displacement, and it is not suitable for high-precision scenes; (2) magnetic grating is easy to demagnetize in high-temperature environment, resulting in signal drift or failure; (3) sensitive to electromagnetic interference, additional magnetic shielding design is needed, which increases the volume and cost of the system; (4) strict installation precision is required, and it is difficult to control the gap between magnetic grating ruler and sensor.
[0004] Therefore, how to improve the environmental adaptability of encoder, reduce cost and improve system reliability has become a problem to be solved. UTILITY MODEL CONTENTS
[0005] The utility model aims at solving the above problems and provides an inductance encoder for rotary motor, which is simple in structure and reasonable in design.
[0006] The utility model realizes the above-mentioned purposes through the following technical solutions:
[0007] An inductance encoder for rotary motor comprises:
[0008] The signal receiving and demodulating module comprises a rotor plate, a stator coil plate and a dual-channel inductive sensor chip, the rotor plate is connected with a rotating shaft part of a rotating motor to be measured, the stator coil plate comprises an excitation coil and a receiving coil, the excitation coil and the receiving coil are arranged on the rotor plate, wherein non-contact electromagnetic induction is formed among the rotor plate, the excitation coil and the receiving coil, a signal receiving end of the inductive sensor chip is electrically connected with a signal output end of the receiving coil, the inductive sensor chip is used for demodulating an amplitude modulation signal on the receiving coil and converting the amplitude modulation signal into a sine-cosine signal;
[0009] The signal receiving and demodulating module is connected with a signal processing module, the signal processing module is used for receiving the sine-cosine signal output by the inductive sensor chip and performing signal processing on the sine-cosine signal to obtain signal information.
[0010] The signal processing module is connected with a signal decoding and output module, the signal decoding and output module is used for receiving the signal information and converting the signal information into angle position information of a rotor plate of the motor.
[0011] As a further optimization scheme of the utility model, the rotor plate and the stator coil plate are both PCB base material plates.
[0012] As a further optimization scheme of the utility model, the inductive sensor chip comprises a demodulating module, the demodulating module is used for converting the amplitude modulation signal into the sine-cosine signal.
[0013] As a further optimization scheme of the utility model, the signal processing module comprises an amplifying module, a filtering module and a differential single-end module, the amplifying module, the filtering module and the differential single-end module are connected in series in an electrical manner.
[0014] The differential single-end module is used for processing a signal which is output by the inductive sensor chip, sequentially undergoes amplification processing of the amplifying module and filtering processing of the filtering module.
[0015] As a further optimization scheme of the utility model, the filtering module comprises an RC filter.
[0016] As a further optimization scheme of the utility model, the signal decoding and output module comprises an analog-digital conversion module, the analog-digital conversion module is arranged on a single-chip microcomputer, the analog-digital conversion module is used for receiving a single-end sine-cosine signal and converting the single-end sine-cosine signal into a digital signal, the single-chip microcomputer is used for receiving the digital signal and decoding the digital signal into angle position information of a rotor of a rotating motor based on a decoding algorithm.
[0017] As a further optimization scheme of the utility model, the analog-digital conversion module comprises an analog-digital converter.
[0018] The inductance encoder for a rotary motor has the advantages that: the inductance encoder is provided by the utility model, adopts non-contact inductance principle, does not need optical or magnetic sensitive element, fundamentally avoids the influence of pollution, high temperature and magnetic field interference on signals, that is, is not interfered by environmental factors and external magnetic field, guarantees measurement precision and reliability, and the inductance sensor adopts differential sine and cosine signal output, can improve anti-interference ability, and adapts to complex application environment.
[0019] Moreover, the encoder adopts double-channel inductance sensor chip, respectively detects sine and cosine signals of single-turn and multi-turn receiving coils, the double-channel inductance sensor chip can offset common mode interference signals, improves decoding precision and anti-interference ability, does not need precise mechanical alignment, simplifies structure, reduces installation complexity, improves mechanical stability, reduces errors caused by mechanical wear or vibration, thereby avoids the wear caused by friction of optical or magnetic element, improves long-term reliability, and reduces maintenance cost.
[0020] In addition, the encoder adopts optimized decoding algorithm based on CORDIC algorithm and lookup table method, improves position detection precision and dynamic response speed. BRIEF DESCRIPTION OF DRAWINGS
[0021] Figure 1 is the encoder structure schematic view of the utility model;
[0022] Figure 2 is the working principle schematic view of the encoder of the utility model. DETAILED DESCRIPTION
[0023] The following further describes the present application in detail with reference to the drawings, and it is necessary to point out that the following specific embodiments are only used for further illustrating the present application, and cannot be understood as limiting the protection scope of the present application, and the skilled in the art can make some non-essential improvements and adjustments to the present application according to the above application content.
[0024] As shown in Figure 1 and Figure 2 The utility model provides a kind of inductance encoder for rotary motor, comprising:
[0025] The signal receiving and demodulating module comprises a rotor plate, a stator coil plate and a dual-channel inductive sensor chip, the rotor plate is connected with a rotating shaft part of a rotating motor to be measured, the stator coil plate comprises an excitation coil and a receiving coil, the excitation coil and the receiving coil are arranged on the rotor plate, wherein non-contact electromagnetic induction is formed among the rotor plate, the excitation coil and the receiving coil, a signal receiving end of the inductive sensor chip is electrically connected with a signal output end of the receiving coil, the inductive sensor chip is used for demodulating an amplitude modulation signal on the receiving coil and converting the amplitude modulation signal into a sine and cosine signal;
[0026] The signal receiving and demodulating module is electrically connected with a signal processing module, the signal processing module is used for receiving the sine and cosine signal output by the inductive sensor chip and performing signal processing on the sine and cosine signal to obtain signal information;
[0027] The signal processing module is electrically connected with a signal decoding and output module, the signal decoding and output module is used for receiving the signal information and converting the signal information into angle position information of the motor rotor plate.
[0028] It should be noted that the mechanical connection among the signal receiving and demodulating module, the signal processing module and the signal decoding and output module is usually realized through a circuit board inside the encoder, and wiring and welding points on the circuit board ensure that the signal can be transmitted from one module to another module.
[0029] In the above embodiment, by adopting the non-contact electromagnetic induction principle, it is unnecessary to use optical or magnetic sensitive elements, and the influence of pollution, high temperature and magnetic field interference on the signal is fundamentally avoided; compared with the grating encoder, the encoder has high environmental adaptability, is not affected by pollutants such as dust, oil stains and water vapor, is not affected by high temperature and magnetic field interference, is suitable for complex industrial environments such as scenes with much dust, high temperature and strong electromagnetic interference, and does not need precise mechanical alignment compared with the magnetic grating encoder, simplifies the structure, reduces the installation complexity, improves the mechanical stability, reduces the error caused by mechanical wear or vibration, avoids the wear caused by the friction of the optical or magnetic elements, improves the long-term reliability and reduces the maintenance cost.
[0030] In addition, the inductive sensor chip with double-channel induction is an integrated chip. By using a high-performance inductive sensor integrated chip with double-channel induction, functions such as excitation coil driving, signal demodulation, filtering, and amplification are integrated. The chip supports double-channel induction and can simultaneously detect single and multiple turns of sine and cosine signals, thereby improving decoding accuracy and anti-interference capability. Specifically, the double-channel induction chip can provide more accurate position information and improve resolution to meet the needs of high-precision motor control, such as robots and numerical control machine tools. This method of using standardized electronic components instead of high-cost optical / magnetic materials can significantly reduce manufacturing costs. Moreover, the double-channel induction chip can cancel common-mode interference signals such as power supply noise and electromagnetic interference, thereby improving the system's anti-interference capability and ensuring stable and reliable signals in complex environments. In addition, the double-channel induction chip can directly output sine and cosine signals, simplifying the decoding algorithm, reducing system complexity, and improving operation efficiency.
[0031] The inductive sensor chip is a custom-developed integrated chip with double-channel induction function and integrated design. The signal receiving, demodulation, filtering, and amplification function modules are integrated on the same or several PCB boards with the coil, reducing the use of external connections and discrete components, making the structure of the entire inductive encoder more compact and more reliable. The inductive sensor chip is also used to receive the oscillation wave induced on the excitation coil. The oscillation wave is generated by welding specific capacitors C1 and C2 at the excitation signal pins of the inductive sensor chip and combining the inductance L of the excitation coil to form an LC oscillation circuit. The inductive sensor chip provides an initial excitation signal for the circuit. In this circuit, the capacitor stores electric field energy, and the inductor stores magnetic field energy. They constantly exchange energy, generating a periodic oscillation excitation signal, i.e., an oscillation wave.
[0032] It should be noted that the type of capacitor used above is a low-temperature coefficient capacitor or an NPO material capacitor. The parameters of the capacitor should be selected according to the inductance of the stator coil plate of the inductive encoder. The excitation signal should be selected according to the inductance value Losc of the excitation coil of the PCB substrate plate to select the appropriate capacitance value. The general range is between 300 pF and 2 nF. The calculation formula of the relationship between the LC oscillation frequency and the capacitor C1, C2 value is:
[0033]
[0034] It should be noted that the rotor plate and the stator coil plate are both PCB substrate plates, which have good electrical insulation performance, ensuring that the excitation coils, receiving coils, and other circuit components on the rotor plate and the stator coil plate do not short circuit with each other or other components, ensuring that the current flows along the designed path, thereby enabling the inductive encoder to work normally.
[0035] The rotor plate is connected with the rotating shaft part of the rotating electric machine to be measured and rotates with the rotating shaft part, the excitation coil and the receiving coil are arranged on the rotor plate, and the receiving coil is placed near the excitation coil. The excitation coil driving circuit inside the double-channel inductive sensor chip outputs an alternating current. The current passes through the excitation coil on the stator coil plate. According to Ampere's law, the excitation coil with the alternating current generates an alternating magnetic field. The strength and direction of the magnetic field change with the current. When the position of the rotor plate relative to the stator coil plate changes, the rotor plate moves in the alternating magnetic field generated by the excitation coil. According to the law of electromagnetic induction, an induced electromotive force and an induced current (eddy current) are generated in the rotor plate. These eddy currents generate their own magnetic field, which further affects the magnetic coupling between the excitation coil and the receiving coil. The receiving coil is used to receive the eddy current signal generated by the rotor plate metal. The distance and relative position between the receiving coil and the excitation coil need to be accurately controlled to ensure the best signal coupling.
[0036] The amplitude modulation signal is an amplitude modulation wave induced on the receiving coil. The amplitude modulation wave is generated by rotating the rotor plate with a specific shape relative to the receiving coil, changing the coupling coefficient of the excitation coil and the receiving coil, and inducing an amplitude modulation wave, i.e. an amplitude modulation signal, on the receiving coil.
[0037] For example, the inductive sensor chip includes a demodulation module, which is an envelope detector circuit integrated inside the inductive sensor chip. The receiving coil's amplitude modulation wave contains information related to the rotating target, i.e. the rotating electric machine. After the inductive sensor chip receives the oscillation wave of the excitation coil and the amplitude modulation wave of the receiving coil, the envelope of the amplitude modulation wave is extracted after demodulation processing, and the amplitude modulation signal is converted and output as a sine and cosine signal corresponding to the rotating target, i.e. the rotating electric machine. In other embodiments, the demodulation module includes an envelope detector integrated on the inductive sensor chip. The envelope detector can be model ADL5502. It only needs 2.5V to 3.3V single power supply to work, and the power consumption is less than 3mA, with the advantage of low power consumption.
[0038] For example, the signal processing module includes an amplification module, a filtering module, and a differential single-ended module, which are electrically connected in series.
[0039] The differential single-ended module is used to process the sine and cosine signals output by the inductive sensor chip after amplification and filtering by the amplification module and the filtering module, respectively.
[0040] Exemplary, the amplification module includes an amplifier, the model of the amplifier is TPA2672-SO1R, and the filter module includes an RC filter including an RC filter circuit formed by using a resistor and a capacitor, and the RC filter circuit can be designed in an integrated manner in the inductive sensor chip. Select appropriate R and C values to meet the requirements, wherein f c is the cutoff frequency, R is the resistance value, and C is the capacitance value.
[0041] It should be noted that the signal after the chip internal circuit demodulates the amplitude modulation wave will be preliminarily filtered and amplified, the RC filter circuit provided on the chip is used to filter the signal generated after demodulation, which effectively removes noise and interference in the signal and effectively improves the anti-interference ability of the signal, so that the signal is more stable in the subsequent transmission and processing process, and the signal generated after demodulation is amplified by the amplifier provided on the chip, which amplifies the amplitude of the weak signal and improves the signal-to-noise ratio of the signal.
[0042] Among them, the sine and cosine signals preliminarily filtered and amplified are further amplified by the amplification circuit through the signal processing module to meet the requirements of subsequent analog-to-digital conversion and improve the signal-to-noise ratio of the signal. It should be noted that the amplification factor is designed according to the signal strength and the input range interval of the analog-to-digital converter; then the signal is filtered to remove high-frequency noise and interference signals and improve the stability and reliability of the signal. The filter type can be a low-pass filter, a band-pass filter or a band-stop filter, which is selected according to the noise characteristics and application requirements;
[0043] The sine and cosine signals preliminarily filtered and amplified are further amplified and filtered by the signal processing module to make the amplitude of the sine and cosine orthogonal signals meet the input range interval of the subsequent analog-to-digital converter (ADC, Analog-to-Digital Converter).
[0044] Then the signal after the further amplification and filtering, i.e. the differential sine and cosine signals, is converted into single-ended sine and cosine signals by the differential-to-single-ended module, and the single-ended sine and cosine signals are signal information.
[0045] Among them, the differential-to-single-ended module includes an operational amplifier, the model of which is TPA2672-SO1R, and the input offset voltage is low, which helps to reduce the error caused by the offset voltage and improve the precision of signal processing.
[0046] Exemplarily, the signal decoding and output module comprises an analog-to-digital conversion module, which is arranged on a microcontroller unit (MCU) and is configured to receive the single-ended cosine signal and convert the single-ended cosine signal into a digital signal, and the microcontroller unit is configured to receive the digital signal and decode the digital signal into the angular position information of the rotor of the rotating motor based on a decoding algorithm.
[0047] Exemplarily, the analog-to-digital conversion module comprises an analog-to-digital converter, and the amplitude of the processed signal of the differential single-ended module is included in the input range interval of the analog-to-digital converter. Exemplarily, the analog-to-digital converter is an analog-to-digital conversion circuit integrated on the microcontroller chip. In other embodiments, the model of the analog-to-digital converter selected is ADS7828, which is integrated on the microcontroller chip board. The resolution of the analog-to-digital converter is 12-bit resolution, which can meet the measurement accuracy of the inductive encoder of the rotating motor. The highest sampling rate is 100kSPS, supports single-ended and differential input, has 8 input channels, can process multiple encoder signals at the same time, reduces the system cost, the interface adopts SPI interface, the connection with the microcontroller is simple and convenient, and the system integration is easy to realize. The model of the microcontroller chip can be selected from Infineon XMC4500, Aurix TM TC275T, GD32F103 series of WCH, etc., which are not limited here.
[0048] The analog-to-digital converter on the microcontroller converts the cosine signal processed by amplification and filtering into a digital signal, providing input data for the subsequent decoding algorithm.
[0049] The decoding algorithm includes an optimized decoding algorithm based on a Coordinate Rotation Digital Computer (CORDIC) algorithm and a lookup table method, which can improve the position detection accuracy and dynamic response speed. The CORDIC algorithm approximates the target angle by iteratively rotating the vector, and can efficiently calculate the trigonometric function without a hardware multiplier, which is suitable for embedded system implementation. However, the number of iterations directly affects the calculation accuracy and speed. The lookup table method pre-stores the sine / cosine values of key angles, and directly looks up the approximate value, which greatly reduces the real-time calculation amount. Therefore, the optimized decoding algorithm is as follows: first, use the lookup table method to quickly obtain the initial angle approximation value, and then use the CORDIC algorithm to iteratively correct the remaining error. This hybrid strategy can reduce signal error, improve position detection accuracy, make up for the lack of inductance encoder resolution compared to grating encoder, and meet the requirements of high-precision application scenarios; the optimized decoding algorithm can also speed up signal processing and improve dynamic response speed, meeting the needs of high-speed motor control; the optimized decoding algorithm can be adjusted according to different application scenarios, such as different motor types and different control algorithms, improving the adaptability of the system and meeting the needs of different types of rotating motor control.
[0050] After obtaining the angle position information of the motor rotor plate through the decoding algorithm, various communication interfaces such as serial port, SPI (Serial Peripheral Interface), I2C (Inter-Integrated Circuit) are provided, which facilitates data exchange with the host computer or other control systems, thereby realizing real-time monitoring and analysis of the running state of the motor. In addition, through these communication interfaces, in addition to transmitting the angle position information of the motor rotor plate to other systems, control instructions from other systems can also be received, realizing the coordinated operation of the entire system.
[0051] For example, the single-chip microcomputer is provided with a fault diagnosis module, the fault diagnosis module is used for detecting and diagnosing system faults and transmitting diagnosis information to the upper computer, through the diagnosis function of the fault diagnosis module, the fault condition of the system, such as sensor fault, can be detected and reported, for example, the fault diagnosis module comprises a temperature sensor, model LM358, which is used for monitoring the temperature of key devices such as inductive sensor chips and single-chip microcomputers, when the temperature of the device is too high or too low and exceeds the normal working range, the possibility of system performance decline or fault occurs, so that the temperature sensor feeds back the temperature information to the single-chip microcomputer for corresponding processing and diagnosis, for example, the fault diagnosis module comprises a power supply monitoring chip, model TPS3808, which is used for monitoring the voltage and current of the system power supply, and can monitor the power supply voltage in real time, when the voltage appears overvoltage, undervoltage or power supply ripple is too large and other abnormal conditions, the single-chip microcomputer can be interrupted in time to inform the power supply related fault, in actual application, the type of fault diagnosis module can be selected according to the fault diagnosis requirement, so that various faults of the system can be diagnosed, and the reliability of the system is improved.
[0052] The upper computer is a computer for monitoring, managing and data processing of various lower computers such as controllers in the system, and is connected with the single-chip microcomputer provided with the fault diagnosis module through a communication interface (such as a serial port, a USB port, an Ethernet port and the like).
[0053] In summary, the inductance encoder for the rotary motor adopts a non-contact electromagnetic induction principle, does not need optical or magnetic sensitive elements, fundamentally avoids the influence of pollution, high temperature and magnetic field interference on signals, and adopts a double-channel inductive sensor chip for detecting sine and cosine signals of single-turn and multi-turn receiving coils respectively, improving decoding precision and anti-interference ability, and when decoding algorithms of digital signals are performed, an optimized decoding algorithm based on combination of CORDIC algorithm and lookup table method is used to obtain a rotary target, i.e. angle position information of a rotor plate of the rotary motor, improving position detection precision and dynamic response speed.
[0054] The above-described embodiments only express several implementation manners of the utility model, the description is more specific and detailed, but it cannot be understood as a limitation on the patent range of the utility model. It should be pointed out that, for ordinary skilled persons in the art, without departing from the concept of the utility model, a number of modifications and improvements can be made, which belong to the protection range of the utility model.
Claims
1. An inductance encoder for a rotary electric machine, characterized by, The application relates to a signal receiving and demodulating module, a signal processing module, a signal decoding and outputting module and a motor rotor angle position information acquisition system. The signal receiving and demodulating module comprises a rotor plate, a stator coil plate and a double-channel inductive sensor chip, the rotor plate is connected with a rotating shaft part of a rotating motor to be measured, the stator coil plate comprises an excitation coil and a receiving coil, the excitation coil and the receiving coil are arranged on the rotor plate, wherein non-contact electromagnetic induction is formed among the rotor plate, the excitation coil and the receiving coil, a signal receiving end of the inductive sensor chip is electrically connected with a signal output end of the receiving coil, the inductive sensor chip is used for demodulating an amplitude modulation signal on the receiving coil and converting the amplitude modulation signal into a sine and cosine signal; The signal receiving and demodulating module is electrically connected with the signal processing module, the signal processing module is used for receiving the sine and cosine signal output by the inductive sensor chip and performing signal processing on the sine and cosine signal to obtain signal information; The signal processing module is electrically connected with the signal decoding and outputting module, the signal decoding and outputting module is used for receiving the signal information and converting the signal information into angle position information of a motor rotor plate.
2. An inductance encoder for a rotary electric machine according to claim 1, characterized in that, The rotor plate and the stator coil plate are both PCB substrate plates.
3. An inductance encoder for a rotary electric machine according to claim 2, characterized in that, The inductive sensor chip comprises a demodulating module which is used for converting the amplitude modulation signal into the sine and cosine signal.
4. An inductance encoder for a rotary electric machine according to claim 3, characterized in that, The signal processing module comprises an amplifying module, a filtering module and a differential single-end module, the amplifying module, the filtering module and the differential single-end module are electrically connected in series; The differential single-end module is used for processing a signal which is output by the inductive sensor chip, sequentially subjected to amplifying processing of the amplifying module and filtering processing of the filtering module.
5. An inductance encoder for a rotary electric machine according to claim 4, characterized in that, The amplifying module comprises an amplifier.
6. An inductance encoder for a rotary electric machine according to claim 5, characterized in that, The filtering module comprises an RC filter.
7. An inductance encoder for a rotary electric machine according to claim 6, characterized in that, The signal decoding and outputting module comprises an analog-digital conversion module, the analog-digital conversion module is arranged on a single-chip microcomputer, the analog-digital conversion module is used for receiving a single-end sine and cosine signal and converting the single-end sine and cosine signal into a digital signal, the single-chip microcomputer is used for receiving the digital signal and decoding and converting the digital signal into angle position information of a rotating motor rotor based on a decoding algorithm.
8. An inductance encoder for a rotary electric machine according to claim 7, characterized in that, The analog-digital conversion module comprises an analog-digital converter.