Small-size micro-power-consumption full-isolation absolute value magnetic encoder and PCB thereof

Abstract

The utility model provides a small-size micro-power-consumption full-isolation absolute value magnetic encoder, which belongs to the field of encoders and comprises an isolation power supply circuit, a step-down circuit, an MCU (Microprogrammed Control Unit), a data transmission circuit, a magnetic field detection circuit and an interface which are all integrated on the same PCB (Printed Circuit Board), the output end of the isolated power supply circuit is connected with the input ends of the step-down circuit and the magnetic field detection circuit, the communication end of the magnetic field detection circuit is connected with the MCU3, the output end of the step-down circuit is connected with the power supply ends of the MCU and the data transmission circuit, and the communication end of the MCU is connected with the communication end of the data transmission circuit. The interface is connected with the input end of the isolation power supply circuit and is connected with the data transmission circuit; the data transmission circuit exchanges data with the outside through an interface; the device has the advantages of full isolation, low power consumption, high precision, high-speed and reliable-speed transmission and the like.

Description

Technical Field

[0001] This utility model relates to the field of encoders, and more specifically, to a small-size, low-power, fully isolated absolute magnetic encoder. Background Technology

[0002] Currently, the mainstream encoders include photoelectric encoders, Hall encoders, and magnetic encoders. Photoelectric encoders have the disadvantages of easily damaged photoelectric components and poor stability. Hall encoders have low accuracy and large size. Magnetic encoders, on the other hand, are small in size, stable and reliable, and have strong anti-interference capabilities. Therefore, magnetic encoders are widely used in many fields.

[0003] While existing magnetic encoders have a certain degree of anti-interference capability, they still suffer from interference problems. For example, in extremely harsh environments, they may fail to read or may produce unreasonable readings. Furthermore, existing anti-interference methods mainly rely on custom-designed shielded cables for data transmission to address interference issues, with little attention paid to processing the encoder and its external circuitry. This approach is simplistic and does not comprehensively consider the anti-interference problem.

[0004] Existing encoders only focus on reading data during the data reading process, and do not have high requirements for data transmission rate and accuracy. They cannot guarantee that the data is correct and arrives on time, and lack reliability in environments with extremely high security requirements.

[0005] Currently, encoders have very low power consumption, but there is still room for improvement. Generally, encoders are only considered for single-use applications, not for combined use, such as in multi-degree-of-freedom robotic arm control. In confined space applications, their size and installation methods have not been adequately considered. Furthermore, encoder interfaces suffer from reverse connection issues, leading to data reading failures or even encoder damage. Therefore, there is a need to design a small-size, low-power, fully isolated absolute magnetic encoder. Utility Model Content

[0006] The purpose of this invention is to overcome the shortcomings of existing encoders and provide a small-size, low-power, fully isolated absolute magnetic encoder.

[0007] To solve the above-mentioned technical problems, this utility model is achieved through the following technical solution:

[0008] A small-size, low-power, fully isolated absolute magnetic encoder includes an isolation power supply circuit 1, a step-down circuit 2, an MCU 3, a data transmission circuit 4, a magnetic field detection circuit 5, and an interface 6.

[0009] The isolation power supply circuit 1, step-down circuit 2, MCU 3, data transmission circuit 4, magnetic field detection circuit 5, and interface 6 are all integrated on the same PCB board. The output of the isolation power supply circuit 1 is connected to the inputs of the step-down circuit 2 and the magnetic field detection circuit 5. The communication terminal of the magnetic field detection circuit 5 is connected to the MCU 3. The output of the step-down circuit 2 is connected to the power supply terminals of the MCU 3 and the data transmission circuit 4. The communication terminal of the MCU 3 is connected to the communication terminal of the data transmission circuit 4. Interface 6 is connected to the input of the isolation power supply circuit 1 and to the data transmission circuit 4. The isolation power supply circuit 1 draws power from the interface and outputs power to the step-down circuit 2 and the magnetic field detection circuit 5. The step-down circuit 2 draws power from the isolation power supply circuit 1 and supplies power to the MCU 3 and the data transmission circuit 4. The MCU 3 communicates with the magnetic field detection circuit 5 and the data transmission circuit 4. The magnetic field detection circuit 5 communicates with the MCU 3 via SPI. The data transmission circuit 4 communicates with the interface 6 via RS485. The data transmission circuit 4 exchanges data with external devices through the interface 6.

[0010] The data transmission circuit 4 is used to convert UART communication to RS485 communication. The data transmission circuit is equipped with a gas discharge tube, a transient diode and EMC. The real-time communication of the data transmission circuit 4 is equipped with verification detection, data buffering and high-speed transceiver functions.

[0011] Interface 6 is used for connecting encoders to enable encoder combination, allowing it to be used in multi-degree-of-freedom control systems for precise acquisition of motor position.

[0012] As a further technical improvement, the isolated power supply circuit 1 includes EMC. The isolation circuit separates the digital ground and analog ground, prevents the conduction of current and interfering substances, provides clean power, and ensures normal operation in the electromagnetic environment without affecting other devices. This helps improve the electromagnetic compatibility of devices and systems and ensures the stability and reliability of devices in the electromagnetic environment.

[0013] As a further technical improvement, the step-down circuit 2 consists of an LDO and two-stage Π-type filters. The LDO provides an acceptable voltage for the MCU and data transmission circuit; the two-stage Π-type filters reduce the power supply ripple after step-down to ensure that communication is not affected by power supply interference.

[0014] As a further technological improvement, MCU3 mainly implements magnetic field strength detection, magnetic field data processing, packet verification of information from the data transmission circuit, low-power settings, and multi-encoder combination processing. Magnetic field detection primarily involves reading data from the magnetic induction chip via SPI communication. The magnetic induction chip can quickly sense changes in the magnetic field and convert the magnetic field strength into 18-bit precision data, ranging from 0 to 2^18. This data represents the real-time position of the motor. The data is filtered, using a Kalman filter to remove unreasonable data. The data transmission circuit primarily uses the MCU's serial port interrupt for receiving and sending information. During serial port reception, a circular queue is first used to store large amounts of data to prevent a large influx of data from causing the MCU to crash. A timer is used to segment the data during reception to achieve real-time detection. Low-power processing mainly involves putting the MCU into a low-power mode when idle and waking it up when the data transmission circuit starts, thereby further reducing power consumption to as low as 0.225W during operation. In the data transmission circuit, the MODBUS protocol is used to verify and segment the data to determine whether the data is correct. The verification design ensures the correctness and reliability of the data. Address verification is added to each frame of data to distinguish which motor position it belongs to, and multiple encoders can be used in combination.

[0015] As a further technical improvement, the data transmission circuit 4 includes a communication isolation circuit and a transient protection circuit. The communication isolation circuit converts the TTL level output by the MCU into a differential output level, improving the signal's anti-interference capability; the transient protection circuit suppresses interference factors such as instantaneous large current or static electricity from damaging the system.

[0016] As a further technical improvement, interface 6 adopts a six-pin design, with the two pins near the edge used to provide power, the two middle pins used for data transmission circuitry, and the two pins near the other edge left floating as a foolproof interface to further protect the circuitry.

[0017] As a further technological improvement, the mechanical design includes four 3mm and two 1.5mm screw positioning holes, which facilitates positioning and installation in confined spaces.

[0018] The beneficial effects of this utility model are as follows:

[0019] 1. This utility model fully considers the operation of the equipment in extreme environments. In addition to the functions that the equipment should have, it also includes power isolation, signal isolation, low power consumption processing, and software filtering.

[0020] 2. This invention boasts high precision and low cost, offering excellent value for money. Its resolution reaches up to 18 bits, meaning it generates data ranging from 0 to 2-18 bits per motor revolution. Compared to other products at the same price point, this invention combines advantages such as full isolation, low power consumption, high precision, and high-speed, reliable data transmission.

[0021] 3. This utility model has a high transmission rate and high reliability. When used alone, the data transmission and reception rate is within 2ms, and when multiple units are used in combination, reliable data delivery is completed within 150ms.

[0022] 4. This utility model is small in size and offers multiple fixing methods. Operation is simple; only a radial magnet needs to be installed at the tail of the motor, and the system can be installed directly above the magnet to collect the motor's real-time position for position and speed control. It includes three 3mm wide positioning holes and two 1.5mm mounting positioning holes.

[0023] 5. This utility model can be used in combination in scenarios requiring the combined operation of multiple motors and precise acquisition of motor positions. Simply connect the output interfaces together, and the control MCU can sequentially query each encoder to obtain the motor position in real time. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of this utility model patent.

[0025] Figure 2 This is the top-level PCB diagram of this utility model patent.

[0026] Figure 3 This is the PCB bottom layer diagram of this utility model patent.

[0027] Figure 4 This is a schematic diagram of the external dimensions of this utility model patent.

[0028] Figure 5 This is a schematic diagram of the position of the radial magnet and the motor in this utility model patent.

[0029] In the picture:

[0030] 1-Isolation power supply circuit, 2-Step-down circuit, 3-MCU, 4-Data transmission circuit, 5-Magnetic field detection, 6-Interface, 7-MCU, 8-Power conversion and filtering physical part, 9-Isolation power supply physical part, 10-Interface, 11-Communication protection circuit, 12-RS485 communication conversion chip, 13-LED display interface location, 14-Magnetic field chip, 15-Absolute encoder physical part, 16-Radial magnet, 17-Motor. Detailed Implementation

[0031] The technical solution of this utility model is further described below, but the scope of protection is not limited thereto.

[0032] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, a small-size, low-cost, low-power, fully isolated absolute magnetic encoder includes an isolation power supply circuit, a step-down circuit, an MCU, a data transmission circuit, a magnetic field detection circuit, an interface, a mechanical shape design, software filtering, data verification, real-time communication, and multiple encoders used in combination.

[0033] The isolated power supply circuit, buck converter circuit, data transmission circuit, magnetic field detection circuit, MCU, and interface are all integrated on the same PCB board. The output of the isolated power supply circuit is connected to the input of the buck converter circuit and the magnetic field detection circuit. The communication terminal of the magnetic field detection circuit is connected to the MCU. The output of the buck converter circuit is connected to the power supply terminals of the MCU and the data transmission circuit. The communication terminal of the MCU is connected to the communication terminal of the data transmission circuit. The interface is connected to the input of the isolated power supply circuit and to the data transmission circuit. The isolated power supply circuit draws power from the interface and outputs power to the buck converter circuit and the magnetic field detection circuit. The buck converter draws power from the isolated power supply circuit and supplies power to the MCU and the data transmission circuit. The MCU communicates with the magnetic field detection circuit and the data transmission circuit. The magnetic field detection circuit 5 communicates with the MCU 3 via SPI. The data transmission circuit 4 communicates with the interface 6 via RS485. The data transmission circuit exchanges data with external devices through the interface.

[0034] The data transmission circuit 4 is used to convert UART communication to RS485 communication. The data transmission circuit is equipped with a gas discharge tube, a transient diode and EMC. The real-time communication of the data transmission circuit 4 is equipped with verification detection, data buffering and high-speed transceiver functions.

[0035] Interface 6 is used for connecting encoders to enable encoder combination, allowing it to be used in multi-degree-of-freedom control systems for precise acquisition of motor position.

[0036] The encoder communicates with an external RS485 bus. The bus sends 8 bits of data to the encoder: the first bit is the encoder address, the second bit is the function code, the third and fourth bits are the register location to be read, the fifth and sixth bits are the number of words to be read, and the seventh and eighth bits are CRC16 check bits. The encoder replies to the bus with 11 bits of data: the first bit is the encoder address, the second bit is the encoder function code, the third and fourth bits are the register address, the fifth bit is the number of bytes read, the sixth to ninth bits are the encoder value, and the tenth and eleventh bits are check bits. Because the encoder has high precision and constantly detects the magnetic field, it can read data even without a radial magnet. Therefore, the first read data that is not zero needs to be preprocessed.

[0037] The MCU uses a circular queue to store data, preventing excessive data from congesting the serial port and causing system crashes. The use of a circular queue increases the chip's data processing margin, allowing an MCU to read data from multiple encoders simultaneously while ensuring the real-time performance and accuracy of the data transmission circuitry.

[0038] This utility model patent is simple to operate, can be quickly fixed to the tail of the motor to accurately measure the motor's running position, the total cost is controlled at around 45 yuan, the size is controlled at 32mm x 32mm x 6mm, the signal transmission and power supply are completely isolated, and the communication speed is below 50ms.

[0039] This utility model patent can be used in combination. In scenarios requiring the operation of multiple motors, simply connect the output interfaces and send the request data command corresponding to each encoder in sequence to quickly read the position of each motor.

[0040] like Figure 5 As shown, this is a reference for the position of the radial magnet and the motor in this utility model. During installation, the magnet should be 1mm to 3mm away from this utility model, and the motor can be replaced with any motor.

[0041] The specific data reading method of this utility model is further described below, including single use and multiple combined use.

[0042] The first step is to install the encoder, following the instructions. Figure 5 The invention is shown with a radial magnet and a motor installed.

[0043] The second step is wiring. Shielded cables should be used for connections whenever possible. When using a single device, locate interface 10 and refer to the silkscreen markings on the left side of interface 10 for wiring. The silkscreen markings indicate that for interface 10, the four pins starting from the right end have the other two left floating. G indicates power and RS485 communication ground; 5 indicates a +5V DC power supply; D- indicates the RS485 B terminal; and D+ indicates the RS485 A terminal. When using multiple devices, first refer to the wiring sequence for a single device for pre-connection, then connect pins 5, G, D-, and D+ together, and finally connect them to the RS485 bus.

[0044] The third step involves data zeroing. The encoder communicates with the external RS485 bus, sending 8 bits of data to the encoder. The first bit is the encoder address, the second is the function code, the third and fourth bits are the register location to be read, the fifth and sixth bits are the number of words to be read, and the seventh and eighth bits are CRC16 checksums. The encoder replies with 11 bits of data. The first bit is the encoder address, the second is the encoder function code, the third and fourth bits are the register address, the fifth bit is the number of bytes to be read, the sixth to ninth bits are the encoder value, and the tenth and eleventh bits are CRC16 checksums. The motor position is calculated as the sixth bit multiplied by 255, the seventh bit multiplied by the eighth bit multiplied by 65535, divided by 2 to the power of 18, and then multiplied by 360 degrees. The current position angle, caused by other factors, needs to be zeroed. After zeroing, the position angle is 0.

[0045] The fourth step is to take the reading. Following the reading rules from the third step, the motor position is calculated as follows: (6th bit multiplied by 255, plus the seventh bit, plus the eighth bit multiplied by 65535, divided by 2 to the power of 18, then multiplied by 360 degrees). This position represents the accurate position of the motor in a single revolution. When using multiple combinations, only the first bit of the bus data transmission needs to be changed, i.e., the address bit of the encoder being read; all other operations remain the same.

Claims

1. A small-size, low-power, fully isolated absolute magnetic encoder, characterized in that, include: The isolated power supply circuit, step-down circuit, MCU, data transmission circuit, magnetic field detection circuit and interface are all integrated on the same PCB board. The output of the isolated power supply circuit is connected to the input of the step-down circuit and the magnetic field detection circuit. The communication terminal of the magnetic field detection circuit is connected to MCU3. The output of the step-down circuit is connected to the power supply terminals of the MCU and the data transmission circuit. The communication terminal of the MCU is connected to the communication terminal of the data transmission circuit. The interface is connected to the input of the isolated power supply circuit and the data transmission circuit. The isolated power supply circuit draws power from the interface and outputs power to the step-down circuit and the magnetic field detection circuit. The step-down circuit draws power from the isolated power supply circuit and supplies power to the MCU and the data transmission circuit. The MCU communicates with the magnetic field detection circuit and the data transmission circuit. The magnetic field detection circuit communicates with the MCU via SPI. The data transmission circuit communicates with the interface via RS485. The data transmission circuit exchanges data with the outside through the interface.

2. The small-volume, low-power, fully isolated absolute magnetic encoder as described in claim 1, characterized in that: The isolated power supply circuit includes EMC (Electronic Control Unit) to separate the digital ground from the analog ground.

3. The small-volume, low-power, fully isolated absolute magnetic encoder as described in claim 1, characterized in that: The data transmission circuit is used to convert UART communication to RS485 communication, and the data transmission circuit is equipped with a gas discharge tube, a transient diode, and EMC.

4. The small-volume, low-power, fully isolated absolute magnetic encoder as described in claim 1, characterized in that: The magnetic field detection circuit is used to detect the magnitude of the magnetic field strength of the radial magnet and convert it into a position angle with 18-bit precision.

5. The small-volume, low-power, fully isolated absolute magnetic encoder as described in claim 1, characterized in that: The real-time communication of the data transmission circuit is equipped with verification detection, data buffering, and high-speed transmission and reception functions.

6. The small-volume, low-power, fully isolated absolute magnetic encoder as described in claim 1, characterized in that: The interface is used for connecting encoders to enable encoder combination, allowing it to be used in multi-degree-of-freedom control systems for precise acquisition of motor position.

7. A PCB board, characterized in that, The PCB board integrates a small-volume, low-power, fully isolated absolute magnetic encoder as described in any one of claims 1-6, and three 3mm and two 1.5mm screw positioning holes are provided at the edge of the PCB board.

Images