Multi-turn absolute value encoder system without battery and gear structure and control method

Abstract

The invention belongs to the technical field of encoder structures, and discloses a battery-free and gear-free multi-ring absolute value encoder system and a control method, and the system comprises an encoder rotor and an encoder stator. The encoder rotor is a magnet coded disc, is fixed on a measured shaft, and has the functions of single-circle absolute value measurement and electromagnetic induction power generation; the encoder stator is integrated with a control circuit board, an electromagnetic induction power generation unit and a single-loop absolute value measurement unit. During power failure, the rotor rotates to generate current through electromagnetic induction power generation, the low-power-consumption system is started, multi-circle position data are stored in the nonvolatile memory, and power failure position memory is achieved. The system adopts pure software multi-circle counting, and a gear structure is not needed; the electromagnetic induction power generation unit adapts to different rotating speeds through the adjustable coil position, and stable power supply is achieved by combining a super capacitor and intelligent power management. The system has the advantages of no battery maintenance, high interference resistance, high precision, high speed, low power consumption and the like, and is suitable for high-reliability scenes such as automation equipment and robots.

Description

Technical Field

[0001] The present invention belongs to the technical field of encoder structures, and in particular relates to a multi-turn absolute encoder system and a control method without a battery or a gear structure. Background Art

[0002] A multi-turn absolute position encoder is a sensor device that measures rotational position, accurately measuring position information over a wide range, over more than one revolution. Multi-turn absolute position encoders typically have a high single-turn measurement resolution of 12 bits or more. They are widely used in automation equipment, robotics, instrumentation, and other fields.

[0003] Due to the periodic nature of rotary motion, while conventional absolute rotary encoders can measure absolute position within a single revolution, they cannot distinguish which revolution the measured position falls within when the range of motion exceeds one revolution. When the encoder operates continuously, the position over multiple revolutions can be determined by position accumulation. However, the absolute position of the initial position within the multi-turn range is unknown at startup. Therefore, in devices where the measured shaft can rotate freely after power failure, if the measured shaft moves more than one revolution during power failure, the encoder will lose absolute position tracking. To address this issue, the position sensor can be set at a specific position (zero position) and moved to this specific position during startup. This process, called zeroing, means that each startup begins at a specific position. This zeroing process not only reduces system efficiency, but is particularly problematic in many motion systems where setting a zero position is not feasible, such as robotic arms that operate continuously. Therefore, the multi-turn absolute encoders mentioned above are widely used in many fields, providing accurate measurements for position detection and motion control.

[0004] Based on the operating principle of multi-turn counting, currently widely used multi-turn absolute encoders are mainly divided into two categories. One type utilizes a gear structure with an additional code disk and measuring unit. For each rotation of the single-turn code disk, the multi-turn code disk rotates one scale mark, thereby achieving multi-turn absolute counting. The additional code disk requires a corresponding measuring unit. This mechanical multi-turn encoder provides accurate multi-turn position measurement, but its complex structure increases its size and manufacturing complexity. The other type is a multi-turn absolute encoder with a battery recovery function. Battery-recoverable multi-turn absolute encoders operate on the same principle as single-turn absolute encoders, but with an additional battery to provide power to measure and record the number of revolutions in the event of a main power outage. An additional multi-turn code disk can be installed for revolution measurement. However, the additional battery increases maintenance complexity and reduces system reliability. Summary of the Invention

[0005] The present invention aims to provide a battery-free and gear-free multi-turn absolute encoder system and control method to solve the above-mentioned technical problems.

[0006] To solve the above technical problems, the specific technical solutions of the battery-free and gear-free multi-turn absolute encoder system and control method of the present invention are as follows:

[0007] A multi-turn absolute encoder system without battery and gear structure, including an encoder rotor and an encoder stator. The encoder rotor is a magnetic code disk fixed on the measured shaft. The magnetic code disk is used for single-turn absolute value measurement and electromagnetic induction power generation. The encoder stator includes an encoder stator control circuit board, an electromagnetic induction power generation unit and a single-turn absolute encoder measurement unit. The single-turn absolute encoder measurement unit is used to measure the single-turn absolute value. The electromagnetic induction power generation unit is used to generate electricity when the system is powered off. The stator control circuit board is used to control the operation of the induction coil drive mechanism and control the entire encoder system. The encoder stator integrates measurement, power generation and control functions. In the event of a power outage Under this condition, if the measured shaft rotates, the encoder rotor also rotates. The magnetic code disk integrated on the encoder rotor generates an induced electromotive force and forms an induced current in the electromagnetic induction power generation unit of the encoder stator. The induced current is rectified and used to start the encoder minimum system and charge the supercapacitor. At this time, the encoder minimum system reads the multi-turn absolute position in low-power mode. When the measured shaft stops rotating, the induced current fails, and the supercapacitor provides power to write the current multi-turn absolute position, especially the multi-turn counter, into the non-volatile storage unit. When the system is powered on next time, the encoder reads this storage unit to obtain the current position. Thus, the multi-turn absolute position of the measured shaft is measured and saved in the case of power failure.

[0008] Furthermore, the electromagnetic induction power generation unit includes an induction coil and an induction coil driving mechanism. The induction coil driving mechanism includes an electromagnet armature, an electromagnet prestressed spring, an electromagnet driving coil, an electromagnet guide rail and an electromagnet core. The induction coil is fixed on the electromagnet armature and faces the encoder rotor side. The electromagnet core is fixedly connected to the encoder stator control circuit board, and the encoder stator control circuit board controls whether it is energized or not. The electromagnet driving coil is fixed on the electromagnet core. The electromagnet guide rail and the electromagnet prestressed spring are fixed between the electromagnet armature and the electromagnet driving coil. When no current passes through the electromagnet driving coil, the electromagnet armature and the induction coil are maintained in a position relatively close to the encoder rotor under the action of the electromagnet prestressed spring, that is, the "low" position; when current passes through the electromagnet driving coil, the electromagnet armature belt moves the dynamic induction coil in a direction away from the encoder rotor, that is, the "high" position.

[0009] Furthermore, the electromagnetic induction power generation unit is arranged on the side of the encoder stator facing the encoder rotor, and the electromagnetic induction power generation unit and the single-turn absolute encoder measuring unit are deployed at positions separated by an angle of 180 degrees, that is, the farthest relative position.

[0010] Furthermore, the single-turn absolute encoder measurement unit utilizes a magnetic single-turn absolute encoder. Different single-turn measurement resolutions are possible, with higher resolutions generally recommended, such as 12 bits or higher, but this is not limiting. Lower resolutions may also be used. The encoder's maximum operating speed is no less than 1050 rad / s, or approximately 10,000 revolutions per minute.

[0011] Furthermore, the encoder system has two operating states:

[0012] a) Normal operation mode, that is, external power supply is available;

[0013] b) Autonomous operation mode, i.e. the working state in which the external power supply is disconnected and the system relies on the electromagnetic induction power generation unit for power supply;

[0014] In normal operation mode, the electromagnetic induction power generation unit is disconnected.

[0015] Furthermore, the encoder system also includes a multi-turn counter and a power supply and protection circuit. The multi-turn counter is used to cooperate with the electromagnetic induction power generation unit to realize multi-turn counting; the power supply and protection circuit is used to provide direct current and system voltage boost and voltage stabilization.

[0016] Furthermore, the multi-turn counter includes a multi-turn counting module and a counting storage module. The counting module is a pure software counter and does not rely on the magnetic code disk. The encoder stator control circuit board determines whether the number of rotations has changed by analyzing the measurement values ​​of adjacent single-turn absolute encoders in the time series. The storage module includes a random access memory and a non-volatile memory and a supercapacitor. The supercapacitor is used to store electrical energy to ensure that the system can complete data storage when the power is off. When the encoder is working, the multi-turn count value is retained in the random access memory. When the encoder is shut down, the multi-turn count value is retained in the non-volatile memory so that the multi-turn count value can be saved in the shutdown state. Regardless of whether it is in normal working mode or autonomous operation mode, as long as the system is started, the supercapacitor is charged by the corresponding power supply circuit. In normal operation mode, the supercapacitor is powered by an external power supply, and in autonomous operation mode, the supercapacitor is powered by an electromagnetic induction power generation unit.

[0017] Furthermore, the power supply and protection circuit includes a rectifier and filter circuit and a boost and voltage stabilization circuit. The rectifier and filter circuit: the induction coil supplies power to the encoder through the rectifier and filter circuit when the external power supply is disconnected; the boost and voltage stabilization circuit is designed with multi-level voltage control and overvoltage protection mechanisms in the autonomous operation mode:

[0018] When the induced voltage exceeds the preset threshold U min When the boost circuit starts, the output rated voltage U rated , which supplies power to the encoder chip, and then passes through the next level voltage regulation / stabilization circuit, from U rated The converted output is 3.3V, which powers the encoder stator control circuit board;

[0019] When the induced voltage exceeds the preset threshold U rated When , the boost circuit is disconnected, the induced voltage is directly input into the voltage regulation / stabilization circuit, and 5V is output to power the encoder stator control circuit board;

[0020] When the induced voltage exceeds the preset threshold U prot+ When the overvoltage protection mechanism is triggered, the electromagnetic induction power generation unit enters the protection mode and the output end is disconnected. A hysteresis mechanism is designed here. Only when the induced voltage drops back to the threshold value U prot- The power generation mode will be re-enabled only when the

[0021] Furthermore, the induced voltage is converted into a uniform voltage through a boost and voltage stabilization circuit. When the induced voltage reaches the threshold, the output voltage should be 5V. The design conditions of the encoder rotor 2 speed when the induction coil position switches from high to low are as follows:

[0022]

[0023] P k ≥i 2 ·R

[0024]

[0025] Where: J is the rotor moment of inertia, ω m is the rotor angular velocity, E k is the rotor kinetic energy, P k is the rotor kinetic energy output power.

[0026] The present invention also discloses a control method for a multi-turn absolute encoder system without a battery or a gear structure, comprising the following steps:

[0027] Step 1: Startup and initialization

[0028] Step 2: Determine whether the external power supply is available and whether the induced voltage is valid.

[0029] When the external power supply is valid, the system enters "normal mode" operation;

[0030] When the external power supply is invalid and the induction voltage is valid, the system enters the "autonomous mode" and is powered by electromagnetic induction;

[0031] In "autonomous mode", the system performs voltage management, protection, and low power consumption functions.

[0032] The system shuts down when both external power supply and induction voltage are invalid;

[0033] Step 3: Charging and supplying power to the supercapacitor:

[0034] The supercapacitor is charged when the system is running, whether in "normal mode" or "autonomous mode";

[0035] Before the system shuts down, it relies on the super capacitor to power the system and store the number of turns in the non-volatile memory unit.

[0036] Step 4: Read multiple laps data during initialization.

[0037] The battery-free and gear-free multi-turn absolute encoder system and control method of the present invention have the following advantages:

[0038] Battery-free design: The electromagnetic induction power generation unit achieves autonomous power supply, avoiding the maintenance problem of regular battery replacement required for traditional battery-powered encoders, and improving the reliability and service life of the system.

[0039] Gearless structure: Using pure software counter to achieve multi-turn counting, eliminating the problems of large size and easy wear brought by traditional mechanical gear structure, making the system structure more compact and more reliable.

[0040] Power-off position retention: Through the cooperation of supercapacitors and non-volatile memory, multi-turn absolute position information can still be accurately recorded and saved in the event of a power outage, ensuring that the position information is not lost after the system is restarted.

[0041] Intelligent power management: With multi-level voltage control and overvoltage protection mechanism, it can automatically adapt to the power generation requirements under different speeds, ensuring power supply reliability at low speeds while avoiding overvoltage risks at high speeds.

[0042] Low-power design: A low-power operation strategy is adopted in autonomous operation mode, including reducing the sampling frequency and shutting down non-essential modules, which significantly extends the continuous operation time in power outages.

[0043] High reliability: The electromagnetic induction coil position is adjustable, which not only ensures the power generation efficiency at low speed, but also avoids the overvoltage problem at high speed, so that the system can work stably at various speeds.

[0044] High measurement accuracy: High-precision position measurement is achieved by using a high-resolution (such as 12-bit and above) magnetic single-turn absolute encoder combined with an accurate multi-turn counting algorithm.

[0045] Wide range of applications: The maximum operating speed can reach about 10,000 rpm (1050 rad / s), which can meet the needs of most high-speed application scenarios.

[0046] Strong anti-interference ability: By arranging the electromagnetic induction power generation unit and the single-turn measurement unit 180 degrees apart, the influence of electromagnetic interference on measurement accuracy is effectively avoided.

[0047] Low maintenance cost: The battery-free and gear-free design greatly reduces maintenance requirements and costs, making it particularly suitable for industrial applications where frequent maintenance is difficult. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a schematic structural diagram of a multi-turn absolute encoder without a battery or a gear structure according to the present invention;

[0049] Figure 2 This is a schematic diagram of the structure of the electromagnetic induction power generation unit of the present invention;

[0050] Figure 3 The encoder system workflow diagram of the present invention;

[0051] Explanation of the symbols in the figure: 1. Measured shaft; 2. Encoder rotor; 3. Encoder stator; 31. Encoder stator control circuit board; 32. Induction coil; 33. Induction coil drive mechanism; 331. Electromagnet armature; 332. Electromagnet prestressed spring; 333. Electromagnet drive coil; 334. Electromagnet guide rail; 335. Electromagnet core; 34. Single-turn absolute encoder measurement unit; DETAILED DESCRIPTION

[0052] In order to better understand the purpose, structure and function of the present invention, the following is a further detailed description of a multi-turn absolute encoder system and control method without battery and gear structure of the present invention in conjunction with the accompanying drawings.

[0053] The present invention discloses a battery-free and gearless multi-turn absolute encoder system comprising an encoder rotor 2 and an encoder stator 3. The encoder rotor 2 is a magnetic code disk fixed to the measured shaft 1. The magnetic code disk is used for single-turn absolute value measurement and electromagnetic induction power generation. The encoder stator 3 comprises an encoder stator control circuit board 31, an electromagnetic induction power generation unit, and a single-turn absolute encoder measurement unit 34. The single-turn absolute encoder measurement unit 34 is used to measure single-turn absolute values, while the electromagnetic induction power generation unit generates power when the system is powered off. The stator control circuit board 31 controls the operation of the induction coil drive mechanism 33 and controls the entire encoder system. The encoder stator 3 integrates measurement, power generation, and control functions. During a power outage, if the measured shaft 1 rotates for some reason, the encoder rotor 2 also rotates. The magnetic code disk integrated on the encoder rotor 2 generates an induced electromotive force in the electromagnetic induction power generation unit of the encoder stator 3, generating an induced current. This induced current is rectified and used to start the encoder minimum system and charge the supercapacitor. The encoder minimum system then reads the multi-turn absolute position in low-power mode. When the measured shaft 1 stops rotating, the inductive current loses power, and the supercapacitor provides power to write the current multi-turn absolute position, specifically the multi-turn counter, to a non-volatile memory cell. The next time the system is powered on, the encoder reads this memory cell to obtain the current position. This allows the multi-turn absolute position of the measured shaft to be measured and stored even in a power outage, meeting the multi-turn absolute position measurement requirements of many automated systems, such as robotics.

[0054] like Figure 2 As shown, the electromagnetic induction power generation unit includes an induction coil 32 and an induction coil drive mechanism 33. The induction coil drive mechanism 33 includes an electromagnetic armature 331, an electromagnetic prestressed spring 332, an electromagnetic drive coil 333, an electromagnetic guide 334, and an electromagnetic core 335. The induction coil 32 is fixed to the electromagnetic armature 331, facing the encoder rotor 2. The electromagnetic core 335 is fixedly connected to the encoder stator control circuit board 31, and the encoder stator control circuit board 31 controls whether it is energized. The electromagnetic drive coil 333 is fixed to the electromagnetic core 335, and the electromagnetic guide 334 and the electromagnetic prestressed spring 332 are fixed between the electromagnetic armature 331 and the electromagnetic drive coil 333. When no current passes through the electromagnet drive coil 333, the electromagnet armature 331 and the induction coil 32 are maintained in a position relatively close to the encoder rotor 2, i.e., the "low" position, under the action of the electromagnet prestressed spring 332; when current passes through the electromagnet drive coil 333, the electromagnet armature 331 drives the induction coil 32 to move away from the encoder rotor 2, i.e., the "high" position.

[0055] Reference Figure 1 and 2As can be seen, the electromagnetic induction power generation unit is located on the side of the encoder stator 3 facing the encoder rotor 2. Because the single-turn absolute encoder measurement unit 34 performs single-turn position measurement based on magnetic principles, the electromagnetic induction power generation unit and the single-turn absolute encoder measurement unit 34 are positioned 180° apart, i.e., at their maximum relative distance. This design prevents current flowing through the electromagnetic induction power generation unit from affecting the angle measurement of the single-turn absolute encoder measurement unit 34.

[0056] As a preferred embodiment, the single-turn absolute encoder measurement unit 34 of the present invention utilizes a magnetic single-turn absolute encoder. Various single-turn measurement resolutions are possible, with higher resolutions, such as 12 bits or higher, generally recommended, but not limited to such. Lower resolutions may also be used. The encoder's maximum operating speed is no less than 1050 rad / s, or approximately 10,000 rpm.

[0057] The encoder system of the present invention has two operating states:

[0058] Shutdown state, that is, non-operating mode.

[0059] Normal operation mode, that is, external power supply is available.

[0060] Autonomous operation mode, that is, the working state in which the external power supply is disconnected, and the system relies on the electromagnetic induction power generation unit for power supply.

[0061] In normal operation mode, the electromagnetic induction power generation unit is disconnected.

[0062] The control system of a multi-turn absolute encoder without a battery or a gear structure of the present invention also includes a multi-turn counter and a power supply and protection circuit. The multi-turn counter is used to cooperate with the electromagnetic induction power generation unit to realize multi-turn counting; the power supply and protection circuit is used to provide direct current and system voltage boost and voltage stabilization.

[0063] The multi-turn counter includes a multi-turn counting module and a count storage module. The counting module is a purely software counter that does not rely on a magnetic code disk. The encoder stator control circuit board 31 determines whether the number of rotations has changed by analyzing the measurement values ​​of adjacent single-turn absolute encoders in a time series. The storage module includes random access memory (RAM), non-volatile memory (NVRAM), and a supercapacitor. The supercapacitor is used to store electrical energy to ensure that the system can complete data storage during power outages. When the encoder is operating, the multi-turn count value is retained in the random access memory (RAM). When the encoder is shut down, the multi-turn count value is retained in non-volatile memory, such as electrically erasable programmable read-only memory (EEROM), to preserve the multi-turn count value in the shutdown state. Whether in normal operating mode or autonomous operation mode, the supercapacitor is charged by the corresponding power supply circuit as soon as the system is started. In normal operation mode, the supercapacitor is powered by an external power supply, while in autonomous operation mode, the supercapacitor is powered by an electromagnetic induction generator.

[0064] The electromagnetic induction power generation unit powers the encoder when external power is unavailable, measuring and recording the current position of the encoder rotor 2. The present invention integrates a magnetic code disk on the encoder rotor 2. Magnetic encoders can share the same magnetic code disk. Other encoder types require a separate magnetic code disk, making magnetic encoders preferred. In addition to the single-turn absolute encoder measurement unit 34, the encoder stator 3 also incorporates an electromagnetic induction power generation unit, including an induction coil 32 and an induction coil drive mechanism 33.

[0065] The voltage of the induced generator is linearly related to the speed of the measured shaft 1:

[0066] e=nvBl

[0067] e=nrω e Bl

[0068] This formula is the calculation formula for induced electromotive force, where e is the induced electromotive force, n is the number of coil turns, r is the radius of the coil from the axis, ω e The angular velocity of the measured shaft, B is the angular position of the input side of the elastic body, l is the length of the coil, and v is the linear velocity of the coil relative to the magnetic field;

[0069] To avoid overvoltage, the maximum induced voltage of the induction coil 32 is designed not to exceed a set threshold, such as 60V, at the highest speed of the encoder.

[0070] The power supply and protection circuit includes a rectifier and filter circuit and a boost and voltage regulator circuit. The rectifier and filter circuit: The induction coil 32 uses the rectifier and filter circuit to power the encoder when the external power supply is disconnected. To simplify the design, a single-phase bridge rectifier and filter circuit is used. The design must ensure that voltage fluctuations do not affect the operation of the boost and voltage regulator circuits described below. If increased power supply stability is required, especially at low speeds, a two-phase or three-phase circuit can also be used.

[0071] The boost and voltage regulation circuit is designed with multi-level voltage control and overvoltage protection mechanism in autonomous operation mode:

[0072] When the induced voltage exceeds the preset threshold U min When the voltage is 0.5V, the boost circuit starts and outputs the rated voltage U rated , such as 5V, to power the encoder chip, and then through the next level voltage regulation / stabilization circuit, it is converted from 5V to output 3.3V to power the encoder stator control circuit board 31.

[0073] When the induced voltage exceeds the preset threshold U rated When the voltage is 5V, the boost circuit is disconnected, and the induced voltage is directly input into the voltage regulating / stabilizing circuit, which outputs 5V to power the encoder stator control circuit board 31.

[0074] When the induced voltage exceeds the preset threshold U prot+ When the voltage drops to 58V, the overvoltage protection mechanism will be triggered, the electromagnetic induction power generation unit will enter the protection mode, and the output terminal will be disconnected. prot- When the voltage drops below 30V, for example, the power generation mode will be re-enabled.

[0075] Preferably, an electronic hardware overvoltage disconnection protection device, such as an overvoltage fuse, is provided at the output end of the electromagnetic induction power generation unit.

[0076] Preferably, a discharge resistor is provided for the electromagnetic induction power generation unit. When the induced voltage exceeds U prot+ When , the discharge resistor is turned on.

[0077] The system's low-power autonomous operation mode:

[0078] When the external power supply is disconnected, energy-saving measures are implemented, including switching the encoder stator control circuit board 31 to a low-power mode, shutting down the input and output modules, and reducing the sampling frequency, for example, to 100 Hz. This energy-saving measure primarily ensures the encoder's performance at low speeds when no power is supplied.

[0079] The distance between the system's induction coil 32 and the encoder rotor 2 is adjustable:

[0080] Due to the design of the electromagnetic induction circuit, the induction coil 32 has two different positions relative to the encoder rotor 2. The induction coil 32 can be switched between these two positions by the electromagnetic armature 331 and the prestressed spring 332. When the electromagnetic armature 331 is de-energized, the induction coil 32 is in the low position, close to the encoder rotor 2, due to the action of the prestressed spring 332. Conversely, if the electromagnetic armature 331 is activated, the induction coil 32 is in the high position, away from the encoder rotor 2.

[0081] If the external power supply is unavailable and the induced voltage (the induction coil 32 is in the “low position”) is lower than or equal to the threshold value U arm+ , such as 30V, at this time the electromagnet drive coil 333 is not connected, and the induction coil 32 remains in the "low position". At this position, the air gap between the encoder rotor 2 and the induction coil 32 is small, the air gap magnetic flux density is large, and the electromagnetic induction effect is strong, which helps to have sufficient induced voltage for starting the sensor system at a lower speed.

[0082] If the external power supply is not available and the induced voltage (coil is in the "low position") is higher than the threshold U arml+, for example, 30V. At this point, the electromagnet drive coil 333 is energized, and the induction coil 32, driven by the electromagnet armature 331, moves to the "high position." At this position, the air gap between the encoder rotor 2 and the induction coil 32 is larger, the air gap magnetic flux density is lower, and the electromagnetic induction effect is weaker. This helps reduce the induced voltage at higher speeds, preventing overvoltage protection from being triggered and protecting the encoder circuit.

[0083] To ensure that the position change of the induction coil 32 does not affect the normal operation of the encoder, when the induction coil 32 moves from the "low position", such as the induction voltage threshold of 30V, to the "high position", the corresponding induction coil 32 at the same speed will have an induction voltage U armh+ , must be higher than the minimum voltage for normal operation of the encoder, such as 5V. armh+ =10V.

[0084] If external power supply is unavailable and the induction coil 32 is already in the "high position", when the induced voltage is lower than the threshold value Uarm-, such as 10V, the electromagnet drive coil 333 is disconnected, and the induction coil 32 moves to the "low position" under the drive of the prestressed spring 332.

[0085] When external power supply is unavailable, when the electromagnet drive coil 333 is turned on, the current of the electromagnet drive coil 333 comes from the kinetic energy of the encoder rotor 2, so the current of the electromagnet armature 331 has a deceleration effect on the rotor. In the stable state, the current of the electromagnet armature 331 can be determined according to the conductor voltage-current relationship:

[0086]

[0087] Where R is the resistance of the electromagnet coil, i is the current of the electromagnet coil, and u is the voltage applied to the electromagnet drive coil 333. R and i are electromagnet design parameters; u is the output voltage of the induced electromotive force after voltage transformation and stabilization, usually 5V.

[0088] In order to ensure that the current of the electromagnet armature 331 is not affected by the induced electromotive force, the induced voltage is converted into a uniform voltage, such as 5V, through a boost and voltage stabilization circuit. According to the design above, when the induced voltage reaches a threshold value, such as 0.5V, the output voltage should be 5V, which effectively supplies power to components such as the encoder stator control circuit board 31, the main control chip, and the electromagnet drive coil 333. In order to ensure that the induction coil 32 switches between high / low positions according to the above-mentioned set logic, it is necessary to ensure during the design that the minimum speed at which the electromagnet drive coil 333 is connected, that is, the speed corresponding to the induction coil 32 switching from high to low, has the kinetic energy to drive the load current when the electromagnet armature 331 is connected. The design conditions for the speed of the encoder rotor 2 when the induction coil 32 position switches from high to low can be based on the following formula.

[0089]

[0090] P k ≥i 2 ·R

[0091]

[0092] Where: J is the rotor moment of inertia, ω m is the rotor angular velocity, E k is the rotor kinetic energy, P k is the rotor kinetic energy output power.

[0093] Reference Figure 3 , you can see the workflow of the entire system of the present invention. It includes the following parts:

[0094] Step 1: Startup and initialization

[0095] Step 2: Determine whether the external power supply is available and whether the induced voltage is valid.

[0096] When the external power supply is valid, the system enters "normal mode" operation (indicated by the dotted box of "normal mode").

[0097] When the external power supply is invalid and the induced voltage is valid, the system enters the "autonomous mode" and is powered by electromagnetic induction (indicated by the dotted box in the "autonomous mode").

[0098] In "autonomous mode", the system performs functions such as voltage management, protection, and low power consumption.

[0099] The system shuts down when both external power supply and induction voltage are invalid.

[0100] Step 3: Charging and supplying power to the supercapacitor:

[0101] The supercapacitor is charged when the system is running, regardless of whether it is in "normal mode" or "autonomous mode". Before the system is shut down, it relies on the supercapacitor to power the multi-turn number and store it in a non-volatile memory unit (EEPROM).

[0102] Step 4: Read multiple lap data during initialization (not directly expressed in the figure).

[0103] It will be understood that the present invention is described by way of some embodiments, and it will be appreciated by those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are intended to be protected by the present invention.

Claims

1. A multi-turn absolute encoder system without a battery or a gear structure, comprising an encoder rotor (2) and an encoder stator (3), characterized in that: The encoder rotor (2) is a magnetic code disk fixed on the measured shaft (1). The magnetic code disk is used for single-turn absolute value measurement and electromagnetic induction power generation. The encoder stator (3) includes an encoder stator control circuit board (31), an electromagnetic induction power generation unit and a single-turn absolute value encoder measurement unit (34). The single-turn absolute value encoder measurement unit (34) is used to measure the single-turn absolute value. The electromagnetic induction power generation unit is used to generate electricity when the system is powered off. The stator control circuit board (31) is used to control the operation of the induction coil drive mechanism (33) and control the entire encoder system. The encoder stator (3) integrates measurement, power generation and control functions. In the case of power failure, if the measured shaft (1) When the encoder rotor (2) rotates, the encoder rotor (2) also rotates accordingly. The magnetic code disk integrated on the encoder rotor (2) generates an induced electromotive force and forms an induced current in the electromagnetic induction power generation unit of the encoder stator (3). The induced current is rectified and used to start the encoder minimum system and charge the super capacitor. At this time, the encoder minimum system reads the multi-turn absolute position in a low-power mode. When the measured shaft (1) stops rotating, the induced current fails. The super capacitor provides power to write the current multi-turn absolute position, especially the multi-turn counter, into the non-volatile storage unit. When the system is powered on next time, the encoder reads the storage unit to obtain the current position. Therefore, the multi-turn absolute position of the measured shaft is measured and saved in the case of power failure.

2. The battery-free and gear-free multi-turn absolute encoder system according to claim 1, characterized in that: The electromagnetic induction power generation unit comprises an induction coil (32) and an induction coil driving mechanism (33). The induction coil driving mechanism (33) comprises an electromagnet armature (331), an electromagnet prestressed spring (332), an electromagnet driving coil (333), an electromagnet guide rail (334) and an electromagnet core (335). The induction coil (32) is fixed on the electromagnet armature (331) and faces the encoder rotor (2). The electromagnet core (335) is fixedly connected to the encoder stator control circuit board (31). Whether the encoder stator control circuit board (31) controls whether the encoder is energized or not. The electromagnet driving coil (333) is fixedly connected to the encoder stator control circuit board (31). The electromagnet guide rail (334) and the electromagnet prestressed spring (332) are fixed on the electromagnet core (335), and are fixed between the electromagnet armature (331) and the electromagnet drive coil (333). When no current flows through the electromagnet drive coil (333), the electromagnet armature (331) and the induction coil (32) are kept in a position relatively close to the encoder rotor (2) under the action of the electromagnet prestressed spring (332), i.e., a "low" position. When current flows through the electromagnet drive coil (333), the electromagnet armature (331) drives the induction coil (32) to move in a direction away from the encoder rotor (2), i.e., a "high" position.

3. The multi-turn absolute encoder system without battery and gear structure according to claim 1, characterized in that: The electromagnetic induction power generation unit is arranged on the side of the encoder stator (3) facing the encoder rotor (2), and the electromagnetic induction power generation unit and the single-turn absolute value encoder measurement unit (34) are deployed at positions separated by an angle of 180 degrees, that is, the farthest relative position.

4. The multi-turn absolute encoder system without battery and gear structure according to claim 1, characterized in that: The single-turn absolute value encoder measurement unit (34) uses a magnetic single-turn absolute value encoder. Different single-turn measurement resolutions can be used. Generally, a higher resolution, such as 12 bits or higher, is recommended, but it is not limited thereto. A lower resolution can also be used. The maximum operating speed of the encoder is not less than 1050 rad / s, that is, about 10,000 revolutions per minute.

5. The multi-turn absolute encoder system without battery and gear structure according to claim 1, characterized in that: The encoder system has two operating states: a) Normal operation mode, that is, external power supply is available; b) Autonomous operation mode, i.e. the working state in which the external power supply is disconnected and the system relies on the electromagnetic induction power generation unit for power supply; In normal operation mode, the electromagnetic induction power generation unit is disconnected.

6. The battery-free and gear-free multi-turn absolute encoder system according to claim 1, characterized in that: The encoder system also includes a multi-turn counter and a power supply and protection circuit. The multi-turn counter is used to cooperate with the electromagnetic induction power generation unit to achieve multi-turn counting; the power supply and protection circuit is used to provide direct current and system voltage boost and voltage stabilization.

7. The battery-free and gear-free multi-turn absolute encoder system according to claim 6, characterized in that: The multi-turn counter includes a multi-turn counting module and a counting storage module. The counting module is a pure software counter and does not rely on a magnetic code disk. The encoder stator control circuit board (31) determines whether the number of rotations has changed by analyzing the measurement values ​​of adjacent single-turn absolute encoders in a time series. The storage module includes a random access memory and a non-volatile memory and a super capacitor. The super capacitor is used to store electrical energy to ensure that the system can complete data storage when power is off. When the encoder is working, the multi-turn count value is retained in the random access memory. When the encoder is turned off, the multi-turn count value is retained in the non-volatile memory to save the multi-turn count value in the shutdown state. Whether in normal working mode or autonomous operation mode, as long as the system is started, the supercapacitor is charged by the corresponding power supply circuit; in normal operation mode, the supercapacitor is powered by an external power supply, and in autonomous operation mode, the supercapacitor is powered by the electromagnetic induction power generation unit.

8. The multi-turn absolute encoder system without battery and gear structure according to claim 6, characterized in that: The power supply and protection circuit includes a rectifier filter circuit and a boost and voltage stabilization circuit. The rectifier filter circuit: the induction coil (32) supplies power to the encoder through the rectifier filter circuit when the external power supply is disconnected; the boost and voltage stabilization circuit is designed with a multi-level voltage control and overvoltage protection mechanism in the autonomous operation mode: When the induced voltage exceeds the preset threshold U min When the boost circuit starts, the output rated voltage U rated , which supplies power to the encoder chip, and then passes through the next level voltage regulation / stabilization circuit, from U rated The converted output is 3.3V, which is used to power the encoder stator control circuit board (31); When the induced voltage exceeds the preset threshold U rated When , the boost circuit is disconnected, the induced voltage is directly input into the voltage regulating / stabilizing circuit, and 5V is output to supply power to the encoder stator control circuit board (31); When the induced voltage exceeds the preset threshold U prot+ When the overvoltage protection mechanism is triggered, the electromagnetic induction power generation unit enters the protection mode and the output end is disconnected. A hysteresis mechanism is designed here. Only when the induced voltage drops back to the threshold value U prot- The power generation mode will be re-enabled only when the 9. The battery-free and gear-free multi-turn absolute encoder system according to claim 6, characterized in that: The induced voltage is converted into a uniform voltage by the boost and voltage stabilization circuit. When the induced voltage reaches the threshold, the output voltage should be 5V. The speed of the encoder rotor (2) when the position of the induction coil (32) switches from high to low is designed according to the following formula: P k ≥i 2 ·R Where: J is the rotor moment of inertia, ω m is the rotor angular velocity, E k is the rotor kinetic energy, P k is the rotor kinetic energy output power.

10. A control method for a multi-turn absolute encoder system without a battery or a gear structure according to any one of claims 1 to 9, characterized in that: The steps include: Step 1: Startup and initialization Step 2: Determine whether the external power supply is available and whether the induced voltage is valid. When the external power supply is valid, the system enters "normal mode" operation; When the external power supply is invalid and the induction voltage is valid, the system enters "autonomous mode" and is powered by electromagnetic induction; In "autonomous mode", the system performs voltage management, protection, and low power consumption functions. The system shuts down when both external power supply and induction voltage are invalid; Step 3: Charging and supplying power to the supercapacitor: The supercapacitor is charged when the system is running, regardless of "normal mode" or "autonomous mode"; Before the system shuts down, it relies on the super capacitor to power the system and store the number of turns in the non-volatile memory unit. Step 4: Read multiple laps data during initialization.

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