Magnetic encoder

Abstract

The invention discloses a magnetic encoder, and the encoder comprises a magnetic sensor which is used for generating an amplitude modulation signal in a rotating magnetic field under the drive of a high-frequency AC signal; the two magnetic switch elements generate orthogonal pulse signals with phase difference in the rotating magnetic field, and the orthogonal pulse signals serve as additional quadrants; the signal processing unit is used for generating a high-frequency alternating current signal; signal processing is carried out on the amplitude modulation signal output by the magnetic sensor to obtain a digital demodulation signal, and the signal processing sequentially comprises differential-to-single-ended processing, amplification processing, high-pass filtering processing and demodulation processing; position information is calculated based on the digital demodulation signal and the additional quadrant. The magnetic encoder provided by the invention improves the resolution of the rotation angle of the rotor.

Description

Technical Field

[0001] The present invention relates to a magnetic encoder. Background Art

[0002] A magnetic encoder is an angle or position sensor based on magnetic field detection, which is widely used in industrial automation, robotics, motor control and other fields. It measures the rotational angle or linear displacement by detecting the change of the magnetic field.

[0003] The magnetic encoder has a simple structure, has a significant cost advantage compared with an optical encoder, and has advantages such as resistance to powder layer and oil pollution. A common magnetic encoder usually uses a pair of pole permanent magnets as a code disk, which rotates with the rotor of the motor to generate an alternating NS magnetic field above the permanent magnet. By detecting the change of the rotating magnetic field with a magnetic sensor, it is further converted into a change of the position signal. Commonly used magnetic sensors include Hall effect sensors, and MR sensors such as AMR (anisotropic magnetoresistance) sensors, GMR (giant magnetoresistance) sensors and TMR (tunnel magnetoresistance).

[0004] Under a magnet with single pair of pole magnetization, to improve the resolution of the magnetic encoder, it is very dependent on the quality of the signal output of the magnetic element. The traditional scheme supplies a DC voltage to magnetic detection elements such as AMR. The output signal of magnetic detection elements such as AMR is relatively weak, and usually requires dozens of times of amplification by the backend for processing. This significantly amplifies the noise and temperature drift of electronic devices such as operational amplifiers and resistors, resulting in an increase in the signal noise output by magnetic elements such as AMR, which limits the improvement of the effective resolution of the magnetic encoder.

[0005] The output signal of the traditional magnetic encoder in the magnetic detection element (such as AMR) is usually only dozens of millivolts, and it needs to be amplified dozens of times by an integrated chip such as an operational amplifier before it is suitable for processing by the ADC (analog-to-digital conversion module) in the micro control unit. However, the operational amplifier itself has flicker noise and white noise, and the resistors configured outside the operational amplifier also have thermal noise, and these noises are amplified with the amplification multiple. Since the noise of the device is distributed within the entire bandwidth, its magnitude is closely related to the circuit bandwidth, and the larger the bandwidth, the greater the noise. Summary of the Invention

[0006] An embodiment of the present application provides a magnetic encoder, including: A magnetic sensor, which is used to generate an amplitude-modulated signal in a rotating magnetic field under the drive of a high-frequency AC signal; Two magnetic switch elements, which generate orthogonal pulse signals with a phase difference in the rotating magnetic field as an additional quadrant; A signal processing unit, which is used for: Generating the high-frequency AC signal; The amplitude-modulated signal output by the magnetic sensor is subjected to signal processing to obtain a digital demodulation signal. The signal processing sequentially includes differential-to-single-ended processing, amplification processing, high-pass filtering processing, and demodulation processing; Based on the digital demodulation signal and the additional quadrant, the position information is calculated.

[0007] The magnetic encoder of the present invention uses a high-frequency alternating current signal generated by an MCU to drive an AMR sensor. The AMR sensor outputs an amplitude-modulated signal, so that the spectrum of the signal output by the AMR sensor is shifted to a high frequency. In combination with a high-pass or band-pass filter circuit during signal amplification, low-frequency noise in the signal is suppressed, and low-pass filtering is performed after sampling processing, and the noise at high frequencies is filtered out. Therefore, the high-frequency and low-frequency noise of devices such as operational amplifiers is effectively limited, and the signal quality of the AMR sensor output is significantly improved.

[0008] Further, the MCU calculates the rotor rotation angle based on the signal output by the AMR sensor and the additional quadrant. While effectively suppressing noise and thus improving the signal quality, the resolution of the rotor rotation angle can be significantly improved, that is, the resolution of the magnetic encoder is improved. Brief Description of the Drawings

[0009] Figure 1 Shows a schematic structural diagram of a magnetic encoder according to a first embodiment of the present application; Figure 2 Shows a structural diagram of a high-pass filter circuit and a synchronous extreme value sampling and holding circuit according to a first embodiment of the present application; Figure 3 Shows a schematic diagram of narrow pulse sampling triggering of a narrow wave pulse signal according to an embodiment of the present application.

[0010] Figure 4 Shows a schematic structural diagram of a magnetic encoder according to a second embodiment of the present application.

[0011] Description of the Reference Numerals First magnetic encoder 1 First magnetic switch element 121 Second magnetic switch element 122 Single-chip microcomputer MCU 14 AMR sensor 11 High-frequency alternating current signal S Sine amplitude-modulated signal 111 Cosine amplitude-modulated signal 112 First processing path 13, 13’ Differential-to-single-ended circuit 131, 131’ Amplification circuit 132, 132’ High-pass or band-pass filter circuit 133, 133’ Synchronous extreme value sampling and holding circuits 134, 134' Low-pass filter circuits 135, 135' Narrow-wave pulse signal P Excitation square wave generation unit 141 Rotation angle calculation unit 142 Capacitor C19, resistor R15, resistor R13, operational amplifier U13-B Analog switch U7, capacitor C5, operational amplifier U9-B Second magnetic encoder 2 Second processing paths 23, 23' Microcontroller MCU 24 Data processing unit 242 Specific implementation manners

[0012] Exemplary embodiments of the present application include, but are not limited to, magnetic encoders.

[0013] Embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0014] Figure 1 The structural schematic diagram of the first magnetic encoder 1 of the first embodiment of the present application is shown. As Figure 1 shown, the first magnetic encoder 1 includes a magnetic sensor, two magnetic switch elements (i.e., the first magnetic switch element 121 and the second magnetic switch element 122), and a signal processing unit. The signal processing unit includes first processing paths 13, 13' and a micro control unit. The micro control unit is implemented by a microcontroller MCU 14, for example.

[0015] In this embodiment, the magnetic sensor is implemented by an AMR sensor 11, for example. The AMR sensor 11 contains two Wheatstone bridges that are 45° apart. The rotating magnetic field in the X-Y sensor plane provides two sine and cosine output signals, and it is an angle sensor with an angle measurement range of 180°.

[0016] In current magnetic encoders, the number of pole pairs of the permanent magnet is limited and the overall bandwidth is not high. The output signal frequency of the AMR sensor is within 1Khz. Therefore, in the present invention, the MCU 14 provides a high-frequency alternating current signal S that is much greater than 1Khz (for example, above 10Khz) to the AMR sensor 11. It can be understood that the high-frequency alternating current signal S can be a square wave, a sine wave, a triangular wave, etc.

[0017] In this embodiment, for example, the high-frequency alternating current signal S is a high-frequency square wave signal and is generated by the excitation square wave generation unit 141 in the MCU 14.

[0018] As the motor rotor (not shown in the figure) in the first magnetic encoder 1 rotates, the permanent magnet (not shown in the figure) mounted thereon rotates, generating a rotating magnetic field. Driven by the high-frequency AC signal S, the AMR sensor 11 generates an amplitude-modulated signal in the rotating magnetic field, including an orthogonal sine amplitude-modulated signal 111 and a cosine amplitude-modulated signal 112, that is, two amplitude-modulated signals with sine and cosine envelopes. It can be understood that the sine amplitude-modulated signal 111 includes Sin+ signal and Sin- signal, and the cosine amplitude-modulated signal 112 includes Cos+ signal and Cos- signal.

[0019] As Figure 1 shown, the first magnetic encoder 1 further includes two magnetic switch elements, that is, the first magnetic switch element 121 and the second magnetic switch element 122, which are placed with a 90° misalignment in the rotating magnetic field. In a rotating magnetic field, the first magnetic switch element 121 and the second magnetic switch element 122 output orthogonal pulse signals with a phase difference (e.g., 90°), which serve as an additional quadrant, enabling the measurement angle range of the AMR sensor 11 to be extended from 180° to 360°. This is a commonly used method for generating an additional quadrant in magnetic encoders, so it will not be described in detail here.

[0020] The signal processing unit processes the sine amplitude-modulated signal 111 and the cosine amplitude-modulated signal 112 output by the magnetic sensor 11 respectively to obtain digital demodulation signals. The signal processing sequentially includes differential-to-single-ended processing, amplification processing, high-pass filtering processing, and demodulation processing.

[0021] As Figure 1 shown, a corresponding first processing path 13 is set for the sine amplitude-modulated signal 111. The first processing path 13 includes a differential-to-single-ended circuit 131, an amplification circuit 132, a high-pass or band-pass filtering circuit 133, a synchronous extremum sampling and holding circuit 134, and a low-pass filtering circuit 135 connected in sequence.

[0022] The differential-to-single-ended circuit 131 performs differential-to-single-ended processing on the received sine amplitude-modulated signal 111, converts the sine amplitude-modulated signal 111 as a differential signal into a single-ended signal, and then the amplification circuit 132 amplifies the single-ended signal. Since the amplitude of the signal output by the AMR sensor 11 is usually small, an amplifier is needed to amplify the signal to improve the signal strength and signal-to-noise ratio for subsequent processing and analysis.

[0023] Next, the high-pass or band-pass filtering circuit 133 performs high-pass filtering processing on the amplified single-ended signal to ensure that the high-frequency signal of the excitation frequency can pass through with basically no attenuation, while suppressing low-frequency signals (e.g., low-frequency noise and interference).

[0024] The demodulation process includes: the synchronous extreme value sampling and holding circuit 134 samples the high-frequency signal that has passed through the high-pass or band-pass filter circuit 133 to obtain the high-frequency signal and the analog demodulation signal. After passing through the low-pass filter circuit 135, the analog demodulation signal is output, and the analog-to-digital conversion module ADC1 in the MCU 14 performs analog-to-digital conversion on the analog demodulation signal to obtain the digital demodulation signal.

[0025] Specifically, the synchronous extreme value sampling and holding circuit 134 samples the high-frequency signal to obtain a stepped analog demodulation signal. Among them, the sampling process performed by the synchronous extreme value sampling and holding circuit 134 on the amplitude-modulated signal (including the high-frequency signal) is synchronous extreme value sampling, and the frequency of the narrow pulse signal P for synchronous extreme value sampling is the same as the frequency of the high-frequency AC signal S.

[0026] The synchronous extreme value sampling and holding circuit 134 performs synchronous extreme value sampling under the trigger of the narrow pulse signal P. Specifically, the narrow pulse signal P is generated by the excitation square wave generating unit 141. The narrow pulse signal P is adjusted to a suitable phase to trigger the gating of the single-pole single-throw analog switch, ensuring that the extreme value points of the amplitude-modulated signal (including the sine amplitude-modulated signal and the cosine amplitude-modulated signal) output by the AMR sensor 11 can be collected, and the voltage of the extreme value points is sampled and held until the next sampling moment arrives.

[0027] It can be understood that the signal after the synchronous extreme value sampling of the synchronous extreme value sampling and holding circuit 134 is an analog signal (i.e., the analog demodulation signal).

[0028] Figure 2 The structure diagram of the high-pass filter circuit 133 and the synchronous extreme value sampling and holding circuit 134 according to the first embodiment of the present application is shown.

[0029] As Figure 2 shown, the capacitor C19, the resistor R15, the resistor R13, and the operational amplifier U13-B constitute the high-pass filter circuit 133 (i.e., a first-order active filter circuit), and the analog switch U7, the capacitor C5, and the operational amplifier U9-B constitute the synchronous extreme value sampling and holding circuit 134 (i.e., the signal sampling circuit). Among them, the synchronous narrow pulse PULSE comes from the output of the I / O port of the MCU 14, and its frequency is the same as the carrier frequency of the SIGNAl amplitude-modulated signal output by the induction coil, and the phase lags behind the carrier frequency of the amplitude-modulated signal by about 90°, that is, the rising edge of the PULSE is aligned near the extreme value point of the SIGNAl, as Figure 3As shown in the schematic diagram of narrow pulse sampling trigger. When PULSE is at a high level, analog switch U7 closes. After capacitor C5 is charged to a voltage near the extreme value of the SIGNAL signal, PULSE becomes low level, analog switch U7 disconnects, and the voltage on capacitor C5 is maintained. Operational amplifier U9-B outputs the extreme value voltage of the current SIGNAL signal until the next switching period (trigger pulse period) arrives and updates the new extreme value voltage.

[0030] The low-pass filter circuit 135 performs low-pass filtering on the stepped analog demodulation signal, filters out high-frequency signals, and outputs the analog demodulation signal, that is, the restored analog sine signal sin.

[0031] As Figure 1 shown, another first processing path 13' corresponding to the cosine amplitude modulation signal 112 is set. Another first processing path 13' includes a differential-to-single-ended circuit 131', an amplifier circuit 132', a high-pass or band-pass filter circuit 133', a synchronous extreme value sampling and holding circuit 134', and a low-pass filter circuit 135' connected in sequence.

[0032] It can be understood that, following a process similar to that of the first processing path 13 for the sine amplitude modulation signal 111, the first processing path 13' for the cosine amplitude modulation signal 112 processes the cosine amplitude modulation signal 112, and finally the low-pass filter circuit 135' outputs the analog demodulation signal, that is, the restored analog cosine signal cos.

[0033] In Figure 1 it is shown that the corresponding first processing paths 13 and 13' are respectively set for the sine amplitude modulation signal 111 and the cosine amplitude modulation signal 112. It can be understood that, as an alternative, a common first processing path can be set for the sine amplitude modulation signal 111 and the cosine amplitude modulation signal 112, thereby reducing the number of circuit components, and thus reducing the manufacturing cost and circuit complexity of the first magnetic encoder 1.

[0034] Next, the analog-to-digital conversion module ADC in the MCU 14 performs analog-to-digital conversion on the analog demodulation signal, and calculates the position information based on the digitally demodulated signal after analog-to-digital conversion and the additional quadrant.

[0035] Specifically, as Figure 1 shown, the MCU 14 includes, for example, analog-to-digital conversion modules ADC1 and ADC2. ADC1 performs analog-to-digital conversion on the analog sine signal sin to obtain a digital sine signal, and ADC2 performs analog-to-digital conversion on the analog cosine signal cos to obtain a digital cosine signal.

[0036] It can be understood that the digitally demodulated signal obtained after being processed by the signal processing unit includes the restored digital sine signal and the restored digital cosine signal.

[0037] Then, for example, the rotation angle calculation unit 142 in the MCU 14 calculates the position information based on the digitized sine signal and digitized cosine signal after analog-to-digital conversion, and the additional quadrant obtained as described above.

[0038] Specifically, based on the digital demodulation signal (including the digitized sine signal and digitized cosine signal) and the additional quadrant, the arctangent algorithm or the phase-locked loop PLL is used to calculate the position information, which is the rotation angle of the rotor in the first magnetic encoder 1.

[0039] The first magnetic encoder 1 transmits the position information as an output to a host computer, such as a servo drive.

[0040] In the first magnetic encoder 1 of this embodiment, an AC power supply method is used as a carrier for MR (AMR, TMR, GMR, etc.) magnetic elements. The amplitude-modulated signal output by the AC-powered MR magnetic elements is sequentially subjected to differential-to-single-ended processing, amplification processing, high-pass or band-pass filtering processing, and the processed amplitude-modulated signal is sampled and held at the carrier extreme points using a narrow pulse with the same frequency as the carrier, and then low-pass filtered to demodulate the envelope signal, which is sampled by an ADC (analog-to-digital conversion) to convert it into a digital signal (i.e., the digital demodulation signal), and then the rotation angle of the motor rotor is calculated by methods such as the arctangent method or the PLL phase-locked loop. For AMR devices, since the AMR magnetic elements output two-cycle signals within a 360° rotation period, it is necessary to combine the additional quadrant information to calculate the rotation angle of the motor rotor.

[0041] Figure 4 FIG. shows a schematic structural diagram of a second magnetic encoder 2 according to a second embodiment of the present application. Figure 4 The same components as those in Figure 1 are marked with the same symbols. As Figure 4 shown, the second magnetic encoder 2 includes a magnetic sensor, two magnetic switch elements (i.e., a first magnetic switch element 121 and a second magnetic switch element 122), and a signal processing unit. The signal processing unit includes second processing paths 23, 23' and a micro control unit. The micro control unit is implemented by a single-chip microcomputer MCU 24, for example.

[0042] In this embodiment, the magnetic sensor is implemented by an AMR sensor 11, for example. The AMR sensor 11 contains two Wheatstone bridges that are 45° apart. The rotating magnetic field in the X-Y sensor plane provides two sine and cosine output signals, which is an angle sensor with a 180° angle measurement range.

[0043] In current magnetic encoders, the number of pole pairs of the permanent magnet is limited, and the overall bandwidth is not high. The output signal frequency of the AMR sensor is within 1Khz. Therefore, in the present invention, the MCU 24 provides a high-frequency AC signal S much greater than 1Khz (for example, above 10Khz) to the AMR sensor 11. It can be understood that the high-frequency AC signal S can be a square wave, a sine wave, a triangular wave, etc.

[0044] In this embodiment, for example, the high-frequency AC signal S is a high-frequency square wave signal and is generated by the excitation square wave generation unit 141 in the MCU 24.

[0045] As the motor rotor (not shown in the figure) in the second magnetic encoder 2 rotates, the permanent magnet (not shown in the figure) mounted on it rotates, generating a rotating magnetic field. The AMR sensor 11 generates an amplitude-modulated signal in the rotating magnetic field under the drive of the high-frequency AC signal S, including an orthogonal sine amplitude-modulated signal 111 and a cosine amplitude-modulated signal 112, that is, two amplitude-modulated signals with sine and cosine envelopes. It can be understood that the sine amplitude-modulated signal 111 includes Sin+ signal and Sin- signal, and the cosine amplitude-modulated signal 112 includes Cos+ signal and Cos- signal.

[0046] As Figure 4 shown, the second magnetic encoder 2 further includes two magnetic switch elements, that is, the first magnetic switch element 121 and the second magnetic switch element 122, which are placed with a 90° offset in the rotating magnetic field. In a rotating magnetic field, the first magnetic switch element 121 and the second magnetic switch element 122 output orthogonal pulse signals with a phase difference (for example, 90°), and this signal serves as an additional quadrant, enabling the measurement angle range of the AMR sensor 11 to be extended from 180° to 360°. This is a common method for generating additional quadrants in magnetic encoders, so it will not be described in detail here.

[0047] The signal processing unit performs signal processing on the sine amplitude-modulated signal 111 and the cosine amplitude-modulated signal 112 output by the magnetic sensor 11 respectively to obtain digital demodulation signals. The signal processing sequentially includes differential-to-single-ended processing, amplification processing, high-pass filtering processing, and demodulation processing.

[0048] As Figure 4 shown, a corresponding second processing path 23 is set for the sine amplitude-modulated signal 111. The second processing path 23 includes a differential-to-single-ended circuit 131, an amplification circuit 132, and a high-pass or band-pass filtering circuit 133 connected in sequence.

[0049] The differential - to - single - ended circuit 131 performs differential - to - single - ended processing on the received sinusoidal amplitude - modulated signal 111, converts the sinusoidal amplitude - modulated signal 111, which is a differential signal, into a single - ended signal, and then the amplifier circuit 132 amplifies the single - ended signal. Since the amplitude of the signal output by the AMR sensor 11 is usually small, an amplifier is needed to amplify the signal to improve the signal strength and signal - to - noise ratio for subsequent processing and analysis.

[0050] Next, the high - pass or band - pass filter circuit 133 performs high - pass filtering on the amplified single - ended signal to ensure that the high - frequency signal of the excitation frequency can pass through with basically no attenuation, while suppressing low - frequency signals (e.g., low - frequency noise and interference).

[0051] The demodulation process includes: The MCU 24 samples the high - frequency signal that has passed through the high - pass or band - pass filter circuit 133, and then performs low - pass filtering to obtain a digital demodulation signal.

[0052] Specifically, the MCU 24 samples the high - frequency signal that has passed through the high - pass or band - pass filter circuit 133, and then performs digital low - pass filtering to obtain a digital demodulation signal, that is, the restored digital sinusoidal signal.

[0053] As Figure 4 shown, the MCU 24 includes an analog - to - digital conversion module ADC 21. The analog - to - digital conversion module ADC 21 samples the high - frequency signal, and this sampling process is peak sampling. The frequency of the narrow - wave pulse signal P for peak sampling is the same as the frequency of the high - frequency alternating - current signal S, so that the peak points in the high - frequency signal can be sampled. It can be understood that what is obtained after peak sampling is a digital signal.

[0054] In this embodiment, for example, the narrow - wave pulse signal P is generated by the excitation square - wave constant unit 141, and the analog - to - digital conversion module ADC21 performs peak sampling under the trigger of the narrow - wave pulse signal P.

[0055] The MCU 24 also includes a data processing unit 242. The data processing unit 242 performs digital low - pass filtering on this digital signal to obtain a digital demodulation signal, that is, the restored digital sinusoidal signal.

[0056] As shown in 2, a corresponding second processing path 23' is set for the cosine amplitude - modulated signal 112. The second processing path 23' includes a differential - to - single - ended circuit 131', an amplifier circuit 132', and a high - pass or band - pass filter circuit 133' connected in sequence. The MCU 24 also includes an analog - to - digital conversion module ADC22.

[0057] It can be understood that the second processing path 23', the analog-to-digital conversion module ADC22, and the data processing unit 242 similarly process the cosine amplitude-modulated signal 112, and finally obtain a digital demodulation signal, that is, the restored digital cosine signal.

[0058] It can be understood that the digital demodulation signal includes the restored digital sine signal and the restored digital cosine signal.

[0059] In Figure 4 , it is shown that corresponding second processing paths 23 and 23' are respectively set for the sine amplitude-modulated signal 111 and the cosine amplitude-modulated signal 112. It can be understood that, as an alternative, a common second processing path can be set for the sine amplitude-modulated signal 111 and the cosine amplitude-modulated signal 112, so that the number of circuit components can be reduced, thereby reducing the manufacturing cost and circuit complexity of the second magnetic encoder 2.

[0060] Finally, for example, the data processing unit 242 in the MCU 24 calculates the position information, that is, the rotation angle of the rotor in the second magnetic encoder 2, based on the obtained digital sine signal and digital cosine signal, and the additional quadrant obtained as described above, using the arctangent algorithm or the phase-locked loop PLL.

[0061] The second magnetic encoder 2 outputs the position information and transmits it to the host computer, such as a servo driver.

[0062] In the second magnetic encoder 2 of this embodiment, an AC power supply method is used as the carrier for the MR (AMR, TMR, GMR, etc.) magnetic element, and the carrier is generated by the microcontroller MCU. The amplitude-modulated signal output by the AC-powered MR magnetic element is subjected to differential-to-single-ended processing, amplification processing, high-pass or band-pass filtering processing, and passes through a main control chip, such as a microcontroller. The microcontroller generates a trigger signal with the same frequency as the carrier, triggers the internal start of the extreme point sampling in the microcontroller, performs extreme point sampling on the amplitude-modulated signal input to the microcontroller, and calculates the rotation angle of the motor rotor by methods such as the arctangent method or the PLL phase-locked loop. For AMR devices, since the AMR magnetic element outputs two-cycle signals within a 360° rotation cycle, it is necessary to combine the additional quadrant information to calculate the rotation angle of the motor rotor.

[0063] In the above embodiment, the ADC module built in the MCU is used for analog-to-digital conversion. It can be understood that, according to needs, a higher-precision ADC device provided outside the MCU can also be used.

[0064] For the magnetic encoder of the present invention, a high-frequency alternating current signal generated by an MCU is used to drive an AMR sensor. The AMR sensor outputs an amplitude-modulated signal, causing the spectrum of the signal output by the AMR sensor to be shifted to a high frequency. In combination with a high-pass or band-pass filter circuit during signal amplification, low-frequency noise in the signal is suppressed, and after sampling and processing, low-pass filtering is performed to filter out the noise at high frequencies. Therefore, the high-frequency and low-frequency noise of devices such as operational amplifiers is effectively restricted, significantly improving the quality of the signal output by the AMR sensor.

[0065] In addition, the MCU calculates the rotor rotation angle based on the signal output by the AMR sensor and additional quadrants. While effectively suppressing noise and thus improving signal quality, the resolution of the rotor rotation angle can be significantly improved, that is, the resolution of the magnetic encoder is improved.

[0066] Furthermore, in Figure 1 In the first embodiment shown, the sampling (i.e., synchronous extremum sampling) and high-frequency filtering processing in the first magnetic encoder 1 are respectively performed by a synchronous extremum sampling and holding circuit and a low-pass filter circuit, that is, these processes are implemented by hardware (i.e., analog circuits). Completing complex signal processing through analog circuits can better adapt to high-frequency signals and noise environments while ensuring high measurement accuracy and stability.

[0067] In Figure 4 In the second embodiment shown, the sampling (i.e., extremum sampling) and high-frequency filtering (i.e., digital high-frequency filtering) processing in the second magnetic encoder 2 are both performed by the MCU, that is, these processes are implemented by software. Therefore, the hardware part is simplified, the complexity of the analog circuit is reduced, making the magnetic encoder further miniaturized, and at the same time, the requirements for hardware performance are lowered. It can better suit the high-speed ADC sampling ability of modern MCUs, improving the flexibility and reliability of the magnetic encoder.

[0068] In the drawings, some structural or method features may be shown in a specific arrangement and / or order. However, it should be understood that such a specific arrangement and / or ordering may not be required. Instead, in some embodiments, these features may be arranged in a manner and / or order different from that shown in the illustrative drawings. Additionally, including a structural or method feature in a specific figure does not imply that such a feature is required in all embodiments, and in some embodiments, these features may not be included or may be combined with other features.

[0069] It should be noted that each unit / module mentioned in the device embodiments of the present application is a logical unit / module. Physically, a logical unit / module can be a physical unit / module, a part of a physical unit / module, or can be implemented as a combination of multiple physical units / module. The physical implementation manner of these logical units / modules themselves is not the most important. The combination of the functions implemented by these logical units / modules is the key to solving the technical problems proposed by the present application. In addition, in order to highlight the innovative part of the present application, the above device embodiments of the present application do not introduce units / modules that are not closely related to solving the technical problems proposed by the present application, which does not mean that there are no other units / modules in the above device embodiments.

[0070] It should be noted that in the examples and the description of the present patent, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising one" does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0071] Although the present application has been illustrated and described by referring to certain preferred embodiments of the present application, those of ordinary skill in the art should understand that various changes can be made in form and detail without departing from the spirit and scope of the present application.

Claims

1. A magnetic encoder, characterized in that: include: A magnetic sensor for generating an amplitude modulated signal in a rotating magnetic field when driven by a high frequency AC signal; Two magnetic switch elements, the two magnetic switch elements generating orthogonal pulse signals with a phase difference in the rotating magnetic field as an additional quadrant; A signal processing unit, the signal processing unit is used for: generating the high frequency AC signal; Performing signal processing on the amplitude modulated signal output by the magnetic sensor to obtain a digital demodulated signal, wherein the signal processing sequentially includes differential to single-ended processing, amplification processing, high-pass filtering processing, and demodulation processing; Based on the digital demodulated signal and the additional quadrant, position information is calculated.

2. The magnetic encoder according to claim 1, characterized in that The signal processing unit includes a first processing path and a micro control unit, The first processing path includes a differential-to-single-ended circuit, an amplifier circuit, a high-pass or band-pass filter circuit, a synchronous extreme value sampling and holding circuit, and a low-pass filter circuit connected in sequence. Among them, the demodulation processing includes: the synchronous extreme value sampling and holding circuit samples the high-frequency signal after the high-pass filtering processing by the high-pass or band-pass filtering circuit to obtain a high-frequency signal and an analog demodulation signal, and outputs the analog demodulation signal after passing through the low-pass filtering circuit; the analog-to-digital conversion module in the microcontroller unit performs analog-to-digital conversion on the analog demodulation signal to obtain the digital demodulation signal.

3. The magnetic encoder according to claim 2, characterized in that: The sampling process performed by the synchronous extreme value sampling and holding circuit on the high-frequency signal is synchronous extreme value sampling, and the frequency of the narrow wave pulse signal for performing the synchronous extreme value sampling is the same as the frequency of the high-frequency AC signal. Wherein, the synchronous extreme value sampling and holding circuit performs synchronous extreme value sampling under the triggering of the narrow wave pulse signal, The signal after the synchronous extreme value sampling is an analog signal.

4. The magnetic encoder according to claim 1, characterized in that The signal processing unit includes a second processing path and a micro control unit, The second processing path includes a differential-to-single-ended circuit, an amplifier circuit, and a high-pass or band-pass filter circuit connected in sequence. The demodulation process includes: the micro control unit samples the high-frequency signal after the high-pass filtering process by the high-pass or band-pass filtering circuit, and then performs low-pass filtering process to obtain the digital demodulation signal.

5. The magnetic encoder according to claim 4, characterized in that: The sampling process performed by the analog-to-digital conversion module in the microcontroller unit on the high-frequency signal is extreme value sampling, and the frequency of the narrow wave pulse signal for the extreme value sampling is the same as the frequency of the high-frequency AC signal. Wherein, the analog-to-digital conversion module performs extreme value sampling under the triggering of the narrow wave pulse signal, The signal after the extreme value sampling is a digital signal.

6. The magnetic encoder according to claim 2 or 4, characterized in that: The differential-to-single-ended circuit performs the differential-to-single-ended processing on the amplitude modulated signal to convert the amplitude modulated signal as a differential signal into a single-ended signal. The amplifier circuit performs the amplification processing on the single-ended signal. The high-pass or band-pass filter circuit performs the high-pass filter processing on the amplified single-ended signal to obtain the high-frequency signal.

7. The magnetic encoder according to claim 1, characterized in that: The digital demodulated signal includes a restored digital sine signal and a digital cosine signal.

8. The magnetic encoder according to claim 1, characterized in that: The two magnetic switch elements generate orthogonal pulse signals having a phase difference of 90° in the rotating magnetic field.

9. The magnetic encoder according to claim 2, characterized in that: The amplitude modulated signal includes a sine amplitude modulated signal and a cosine amplitude modulated signal, wherein corresponding first processing paths are set for the sine amplitude modulated signal and the cosine amplitude modulated signal respectively, or a common first processing path is set for the sine amplitude modulated signal and the cosine amplitude modulated signal.

10. The magnetic encoder according to claim 4, characterized in that: The amplitude modulated signal includes a sine amplitude modulated signal and a cosine amplitude modulated signal, wherein corresponding second processing paths are set for the sine amplitude modulated signal and the cosine amplitude modulated signal respectively, or a common second processing path is set for the sine amplitude modulated signal and the cosine amplitude modulated signal.

11. The magnetic encoder according to claim 1, characterized in that: Based on the digital demodulated signal and the additional quadrant, the position information is calculated using an inverse tangent algorithm or a phase-locked loop (PLL), The position information is the rotation angle of the rotor in the magnetic encoder.

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