A servo control system of a gyro accelerometer based on a permanent magnet synchronous torque motor

Abstract

The application discloses a gyro accelerometer servo control system based on a permanent magnet synchronous torque motor, which is used for balancing the outer ring interference torque of a gyro accelerometer, and makes the inner ring of the gyro accelerometer work near zero position. The system comprises an inductive encoder, a permanent magnet synchronous torque motor, an inner ring angle sensor, a servo control circuit, a gyro accelerometer inner ring and a gyro accelerometer outer ring. The gyro accelerometer servo control system based on the permanent magnet synchronous torque motor effectively suppresses torque fluctuation and improves torque size performance, solves problems of out-of-step of the servo control system and excessive inner ring angle fluctuation of the gyro accelerometer under vibration conditions, and has the advantages of high servo control precision, strong anti-interference capability and reliable work.

Description

Technical Field

[0001] This invention relates to a gyroscope accelerometer servo control system based on a permanent magnet synchronous torque motor, belonging to the fields of inertial technology and motor servo control technology. Background Technology

[0002] A pendulum-type integrating gyro accelerometer (or simply gyro accelerometer) is used in inertial navigation systems to measure the linear motion of a vehicle relative to inertial space. It utilizes the gyro principle to accurately measure the apparent acceleration of the moving vehicle, and then calculates the vehicle's velocity and position information. The servo control system is a crucial component of the gyro accelerometer, and its performance directly affects the measurement accuracy of the pendulum-type integrating gyro accelerometer.

[0003] The servo control system of a gyro accelerometer consists of an angle measuring device (input), a servo control loop and a torque motor (output actuator), and an inner loop of the gyro accelerometer. Its function is to control the torque motor to generate an outer loop torque by measuring the inner loop's operating angle to balance the frictional torque, thus keeping the inner loop operating near zero. The angle measuring device includes an inner loop angle sensor and an angle encoder. These measure different objects: the inner loop angle sensor measures the accelerometer's inner loop operating angle, while the angle encoder measures the position and speed of the torque motor rotor. The main performance indicators for a servo system are bandwidth and accuracy. The bandwidth of the servo system is primarily limited by the torque motor, while the accuracy is affected by the accuracy of the angle measuring device. The selection and design of these two components directly affect the control accuracy of the servo loop and have a significant impact on the accuracy of the inertial navigation system.

[0004] For example, prior art patent CN 103872965 A discloses a servo control system and method for an oil-supported inertial instrument. In this servo control system, the torque motor is a brushless DC motor, and a switching Hall sensor is used to detect the rotor position, thereby achieving motor commutation. However, because the brushless DC motor uses square wave control, the stator winding inductance affects commutation, preventing the acquisition of an ideal trapezoidal current and resulting in large torque ripple. While the switching Hall sensor can be embedded in the motor body and has a small size, its magnetic rotor structure limits its detection accuracy. Furthermore, the switching Hall sensor is susceptible to external temperature and magnetic field distribution, leading to errors in the output signal. Therefore, appropriate temperature compensation and filtering circuits are required to reliably measure the motor position. Another example is prior art patent CN 102158156 A, which discloses a controllable and monitorable brushless torque motor pulse modulation servo control system. This system also uses a brushless DC motor, employing a comparator and optocoupler isolation to achieve PWM pulse modulation. This pulse modulation scheme is a carrier-based PWM, which has high pulse harmonic distortion and large ripple, making it unfavorable for smooth low-speed motor control. Furthermore, the servo control system has low integration and a relatively complex circuit structure, hindering system miniaturization and high reliability design.

[0005] With the increasing demands for inertial navigation accuracy, current servo control systems for gyroscope accelerometers can no longer meet the requirements for high precision, high reliability, and miniaturization. Therefore, improving the performance and reliability of the servo control system is of great significance for enhancing the measurement accuracy and reliability of gyroscope accelerometers. Summary of the Invention

[0006] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a gyroscope accelerometer servo control system based on a permanent magnet synchronous torque motor.

[0007] The technical solution of this invention is:

[0008] This invention discloses a gyro accelerometer servo control system based on a permanent magnet synchronous torque motor, comprising: an inductive encoder, a permanent magnet synchronous torque motor, an inner loop angle sensor, a servo control circuit, an inner loop of the gyro accelerometer, and an outer loop of the gyro accelerometer; wherein,

[0009] The outer ring of the gyro accelerometer obtains the real-time absolute position and real-time speed of the rotor of the permanent magnet synchronous torque motor;

[0010] The inductive encoder sends the real-time absolute position obtained from the outer ring of the gyro accelerometer to the servo control circuit.

[0011] The permanent magnet synchronous torque motor generates torque under the action of the three-phase current output by the servo control circuit, drives the rotor to rotate, and drives the outer ring of the gyro accelerometer to rotate.

[0012] The inner ring angle sensor is used to measure the inner ring angle of the gyro accelerometer and output it to the servo control circuit.

[0013] The servo control circuit receives the real-time absolute position from the inductive encoder, calculates the current absolute position, and calculates the real-time rotational speed based on the position difference between the current absolute position and the previous absolute position. Simultaneously, it receives the inner ring angle from the inner ring angle sensor, calculates it through the position loop, speed loop, and current loop, and outputs an SVPWM drive signal to adjust the magnitude and direction of the three-phase current acting on the permanent magnet synchronous torque motor. This dynamically balances the interference torque of the outer ring of the gyro accelerometer, stabilizing the inner ring angle of the gyro accelerometer near zero.

[0014] Furthermore, in the above system, the inductive encoder has a resolution of 22 bits, outputs absolute position, outputs data via SSI interface, outputs one absolute position with a period of 1ms, and is powered by +5V DC voltage.

[0015] Furthermore, in the above system, the stator and rotor of the inductive encoder adopt a separate design. The power supply and data transmission wires are led out on one side of the stator, and the rotor has no transmission wires. It is coaxially mounted with the rotor of the permanent magnet synchronous torque motor and installed on the outer ring of the gyro accelerometer.

[0016] Furthermore, in the above system, the servo control circuit includes a control circuit, a drive circuit, and a detection circuit; wherein,

[0017] The control circuit generates a PWM control signal based on the collected data sent by the detection circuit and sends it to the drive circuit.

[0018] The drive circuit controls the permanent magnet synchronous torque motor to work according to the PWM control signal sent by the control circuit;

[0019] The detection circuit collects the three-phase voltage, current, and fault signals of the permanent magnet synchronous torque motor and provides them to the control circuit.

[0020] Furthermore, in the above system, the control circuit includes a three-closed-loop control module, a correction network, a speed and position calculation module, an SVPWM space vector control module, an inverter circuit, a serial communication module, and a fault handling module;

[0021] The three-loop control module, based on the motor rotor position signal output by the speed and position calculation module, uses integral limiting and closed-loop dead zone setting to adjust position, speed, and current, and outputs the α and β axis voltages U in the stationary coordinate system.α U β Provide the SVPWM space vector control module;

[0022] The rotation speed and position calculation module is located in the FPGA chip of the control circuit. It verifies and calculates the real-time absolute position sent by the inductive encoder and provides real-time position information to the DSP chip of the control circuit.

[0023] The correction network corrects the inner ring angle collected by the inner ring angle sensor to provide a target rotational speed for the speed ring;

[0024] The SVPWM space vector control module controls the α and β axis voltages U in the stationary coordinate system. α U β After sector determination and dead-time compensation, six PWM drive signals are output to the inverter circuit.

[0025] The inverter circuit converts 6 PWM drive signals into three-phase sinusoidal current, which is then output to the permanent magnet synchronous torque motor.

[0026] The serial communication module enables data communication between modules and the burning of control programs.

[0027] The fault handling module performs overvoltage protection, overcurrent protection, and overload protection, and triggers protection actions and provides fault information when a fault is detected.

[0028] Furthermore, in the above system, the three-closed-loop control module includes a position regulator, a speed regulator, and a current regulator; wherein,

[0029] The position regulator compares the motor rotor position signal output by the speed and position calculation module with the given target position to obtain the speed reference value, which is then output to the speed regulator.

[0030] The speed regulator compares the rotational speed output from the rotational speed and position calculation module with a speed reference value, and outputs a quadrature-axis current reference value I. qref Send it to the current regulator;

[0031] The current regulator, based on the stator current output by the inverter, obtains the voltage through coordinate transformation and comparison with the set value, and outputs it to the SVPWM space vector control module.

[0032] Furthermore, in the above system, the step of obtaining the voltage based on the stator current output by the inverter through coordinate transformation and comparison with a set value specifically involves:

[0033] Based on the stator current I output by the inverter a I b I cBy transforming to a two-phase stationary coordinate system using Clark transformation, the α-axis and β-axis currents I in the stationary coordinate system are obtained. α I β Then, by performing a Park transformation to a two-phase rotating coordinate system, the direct-axis current I is obtained. d and quadrature axis current I q ;

[0034] Direct-axis current I d and quadrature axis current I q The cross-axis current reference value I sent by the current regulator is respectively compared with the reference value I. qref and direct-axis given current I dref By comparison, the direct-axis voltage U is obtained. d With cross-axis voltage U q ;

[0035] The direct-axis voltage U d With cross-axis voltage U q Perform the inverse Park transformation to obtain the α-axis and β-axis voltages U in the stationary coordinate system. α U β .

[0036] Furthermore, in the above system, the adoption of integral limiting and closed-loop dead zone settings specifically refers to:

[0037] S11, The position regulator obtains the real-time position information of the rotor from feedback;

[0038] S12. Determine whether the deviation between the real-time rotor position information and the target position information is greater than the set dead zone threshold; if yes, proceed directly to step S13; otherwise, clear the PID parameters and exit.

[0039] S13. Determine whether the deviation between the real-time rotor position information and the target position information is less than the integral limit threshold. If so, perform PID control; otherwise, perform PD control first, then perform PID control. Finally, the PID position regulator outputs the speed reference value and sends it to the speed regulator.

[0040] Furthermore, in the above system, the speed regulator adopts segmented interval control, specifically: the deviation between the real-time speed information fed back by the encoder and the target speed is segmented; the control interval is divided into coarse adjustment interval, fine adjustment interval and micro adjustment interval according to the magnitude of the absolute value of the speed deviation; the speed controller uses different PI parameters for different control intervals.

[0041] Furthermore, in the above system, the torque generated by the permanent magnet synchronous torque motor can reach up to 2400 gf.cm.

[0042] The advantages of this invention over the prior art are as follows:

[0043] (1) The torque motor of the gyro accelerometer of this invention adopts a permanent magnet synchronous torque motor. Based on the working characteristics of the inner ring of the gyro accelerometer, it operates in a low-speed, high-torque state, which has the following advantages compared with the currently used brushless DC torque motor:

[0044] 1) The brushless DC motor adopts a six-step commutation control and the back EMF is a square wave. The permanent magnet synchronous motor adopts the space vector modulation method (FOC) for control and the back EMF is a sine wave with lower harmonic content. Therefore, the voltage harmonic content of the permanent magnet synchronous motor has less impact on torque fluctuation and stronger low-speed smooth performance.

[0045] 2) The speed of a permanent magnet synchronous motor depends only on the number of pole pairs and the frequency, and is not affected by the load size. Permanent magnet synchronous torque motors are not affected by fluctuations in external interference torque, resulting in higher control precision and enabling accurate compensation for external friction torque.

[0046] (2) The gyro accelerometer angle encoder of this invention adopts an inductive encoder. Through electromagnetic induction technology, the printed circuit board (PCB) is placed inside the housing, replacing the winding structure of the traditional transformer. Compared with the Hall sensor currently used, it has the following advantages: 1. It can provide the absolute position signal of the motor rotor. After power failure, it can save the position information and the position will not be lost after power is restored; 2. The code disk adopts a 22-bit design with a single-turn resolution of 4194304, which can provide high-precision absolute position information of the outer ring of the gyro accelerometer; 3. It has a compact structure and is easy to install, meeting the needs of instrument miniaturization; 4. It adopts a split structure design, and there are no transmission wires on the rotor, avoiding the introduction of interference torque; 5. The product has a high protection level and can meet the use requirements in harsh environments (high ground temperature, high humidity, high vibration, etc.), improving the reliability and stability of the instrument.

[0047] (3) The gyroscope accelerometer servo control system of this invention adopts a three-closed-loop control system. Based on the existing dual-closed-loop control system, the introduction of a position loop enables the outer ring of the gyroscope accelerometer to be stably stopped at the target position, reducing the mechanical stress on the outer ring shaft during long standby and improving the service life of the gyroscope accelerometer. At the same time, in the design of the speed regulator, a segmented output control method is adopted to improve the fast response capability of the control system.

[0048] (4) The servo control circuit of the gyroscope accelerometer of the present invention uses a DSP+FPGA architecture, which has a high degree of integration and a compact circuit structure. Combined with the working characteristics of the gyroscope accelerometer, the traditional motor vector control method has been optimized, which effectively suppresses the problems of loss of control system steps and excessive fluctuation of inner loop working angle when the gyroscope accelerometer is working under vibration conditions.

[0049] (5) This invention effectively suppresses torque fluctuations and improves torque performance by controlling the permanent magnet synchronous torque motor through rotation vector control. It solves problems such as loss of step in the servo control system and excessive inner loop angle fluctuation when the gyroscope accelerometer is working under vibration conditions. It has the advantages of high servo control accuracy, strong anti-interference ability and reliable operation.

[0050] (6) The present invention designs a gyroscope accelerometer servo control system based on a permanent magnet synchronous torque motor, which realizes the precise balance of the interference torque of the outer ring of the gyroscope accelerometer, and has the advantages of high control accuracy, strong low-speed stability and reliable operation. Attached Figure Description

[0051] Figure 1 This is the overall design diagram of the servo control system applicable to the gyroscope accelerometer in Embodiment 1 of the present invention;

[0052] Figure 2 This is a schematic diagram of the motor vector control system of the present invention;

[0053] Figure 3 This is a flowchart of the motor control interrupt subroutine of the present invention;

[0054] Figure 4 This is a flowchart of the PID control with integral limiting and closed-loop dead zone of the present invention. Detailed Implementation

[0055] The features and advantages of the present invention will become clearer and more apparent from the following detailed description.

[0056] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0057] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0058] like Figure 1 As shown, this invention discloses a gyro accelerometer servo control system based on a permanent magnet synchronous torque motor, comprising: an inductive encoder 1, a permanent magnet synchronous torque motor 2, an inner ring angle sensor 3, a servo control circuit 4, an inner ring of the gyro accelerometer 5, and an outer ring of the gyro accelerometer 6; wherein,

[0059] The outer ring 6 of the gyro accelerometer obtains the real-time absolute position and real-time speed of the rotor of the permanent magnet synchronous torque motor 2;

[0060] The inductive encoder 1 sends the real-time absolute position obtained from the outer ring 6 of the gyroscope accelerometer to the servo control circuit 4;

[0061] The permanent magnet synchronous torque motor 2 generates torque under the action of the three-phase current output by the servo control circuit 4, drives the rotor to rotate, and drives the outer ring 6 of the gyro accelerometer to rotate.

[0062] Inner ring angle sensor 3 is used to measure the inner ring angle of the inner ring 5 of the gyro accelerometer and output it to the servo control circuit 4;

[0063] The servo control circuit 4 receives the real-time absolute position provided by the inductive encoder 1, calculates the current absolute position, and calculates the real-time rotational speed based on the position difference between the current absolute position and the absolute position at the previous moment. At the same time, it receives the inner ring angle provided by the inner ring angle sensor 3. After calculation by the position loop, speed loop and current loop, it outputs the SVPWM drive signal to adjust the magnitude and direction of the three-phase current acting on the permanent magnet synchronous torque motor 2, so as to dynamically balance the interference torque of the outer ring 6 of the gyro accelerometer and stabilize the angle of the inner ring 5 of the gyro accelerometer near the zero position.

[0064] Preferably, the inductive encoder 1 has a resolution of 22 bits, outputs absolute position, outputs data via SSI interface, outputs one absolute position with a period of 1ms, and is powered by +5V DC voltage.

[0065] Preferably, the stator and rotor of the inductive encoder 1 are designed separately. The power supply and data transmission wires are led out on one side of the stator, and the rotor has no transmission wires. It is coaxially mounted with the rotor of the permanent magnet synchronous torque motor 2 and installed on the outer ring 6 of the gyro accelerometer.

[0066] Preferably, the servo control circuit 4 includes a control circuit, a drive circuit, and a detection circuit; wherein,

[0067] The control circuit generates a PWM control signal based on the collected data sent by the detection circuit and sends it to the drive circuit.

[0068] The drive circuit controls the permanent magnet synchronous torque motor 2 to work according to the PWM control signal sent by the control circuit;

[0069] The detection circuit collects the three-phase voltage, current, and fault signals of the permanent magnet synchronous torque motor and provides them to the control circuit.

[0070] Preferably, the control circuit includes a three-closed-loop control module, a correction network, a speed and position calculation module, an SVPWM space vector control module, an inverter circuit, a serial communication module, and a fault handling module;

[0071] The three-loop control module, based on the motor rotor position signal output by the speed and position calculation module, uses integral limiting and closed-loop dead zone setting to adjust position, speed, and current, and outputs the α and β axis voltages U in the stationary coordinate system. α U β Provide the SVPWM space vector control module;

[0072] The speed and position calculation module, located in the FPGA chip of the control circuit, verifies and calculates the real-time absolute position sent by the inductive encoder 1, and provides real-time position information to the DSP chip of the control circuit.

[0073] The calibration network corrects the inner ring angle collected by the inner ring angle sensor, providing the target rotational speed for the speed ring;

[0074] The SVPWM space vector control module controls the α and β axis voltages U in a stationary coordinate system. α U β After sector determination and dead-time compensation, six PWM drive signals are output to the inverter circuit.

[0075] The inverter circuit converts 6 PWM drive signals into three-phase sinusoidal current, which is then output to the permanent magnet synchronous torque motor 2.

[0076] The serial communication module enables data communication between modules and the burning of control programs.

[0077] The fault handling module performs overvoltage protection, overcurrent protection, and overload protection, and triggers protection actions and provides fault information when a fault is detected.

[0078] Preferably, the three-closed-loop control module includes a position regulator, a speed regulator, and a current regulator; wherein,

[0079] The position regulator compares the motor rotor position signal output by the speed and position calculation module with the given target position to obtain the speed reference value, which is then output to the speed regulator.

[0080] The speed regulator compares the rotational speed output from the rotational speed and position calculation module with a speed reference value, and outputs a quadrature-axis current reference value I. qref Send it to the current regulator;

[0081] The current regulator, based on the stator current output by the inverter, obtains the voltage through coordinate transformation and comparison with the set value, and outputs it to the SVPWM space vector control module.

[0082] Preferably, the voltage is obtained based on the stator current output by the inverter, through coordinate transformation and comparison with a set value, specifically as follows:

[0083] Based on the stator current I output by the inverter a I b I c By transforming to a two-phase stationary coordinate system using Clark transformation, the α-axis and β-axis currents I in the stationary coordinate system are obtained. α I β Then, by performing a Park transformation to a two-phase rotating coordinate system, the direct-axis current I is obtained. d and quadrature axis current I q ;

[0084] Direct-axis current I d and quadrature axis current I q The cross-axis current reference value I sent by the current regulator is respectively compared with the reference value I. qref and direct-axis given current I dref By comparison, the direct-axis voltage U is obtained. d With cross-axis voltage U q ;

[0085] The direct-axis voltage U d With cross-axis voltage U q Perform the inverse Park transformation to obtain the α-axis and β-axis voltages U in the stationary coordinate system. α U β .

[0086] Preferably, integral limiting and closed-loop dead zone settings are adopted, specifically:

[0087] S11, The position regulator obtains the real-time position information of the rotor from feedback;

[0088] S12. Determine whether the deviation between the real-time rotor position information and the target position information is greater than the set dead zone threshold; if yes, proceed directly to step S13; otherwise, clear the PID parameters and exit.

[0089] S13. Determine whether the deviation between the real-time rotor position information and the target position information is less than the integral limit threshold. If so, perform PID control; otherwise, perform PD control first, then perform PID control. Finally, the PID position regulator outputs the speed reference value and sends it to the speed regulator.

[0090] Preferably, the speed regulator adopts segmented interval control, specifically: the deviation between the real-time speed information fed back by the encoder and the target speed is segmented; the control interval is divided into coarse adjustment interval, fine adjustment interval and micro adjustment interval according to the magnitude of the absolute value of the speed deviation; the speed controller uses different PI parameters for different control intervals.

[0091] Preferably, the permanent magnet synchronous torque motor 2 can generate a maximum torque of 2400 gf.cm.

[0092] Example

[0093] This embodiment provides a gyroscope accelerometer servo control system based on a permanent magnet synchronous torque motor. The main control chip on the servo control circuit generates a drive signal according to the real-time position information input by the angle encoder and the control program to control the output torque of the servo motor to balance the outer loop interference torque and stabilize the inner loop near zero position.

[0094] As the actuator of the servo system, the permanent magnet synchronous torque motor generates an output torque with high power density and low torque fluctuation in response to the drive signal of the servo control circuit. This torque is used to balance the interference torque of the outer loop and keep the inner loop of the gyro accelerometer stable near zero.

[0095] Inductive encoders are used to measure the rotor speed and position of permanent magnet synchronous motors. Based on the principle of electromagnetic induction, they generate a magnetic field through an electrical conductor. The rotor's positional movement affects the magnetic field, producing a voltage difference. This electrical signal is then converted and calculated to obtain a mechanical signal. During installation, the inductive encoder is coaxially connected to the motor rotor. After digitizing the signal, it is output via the SSI protocol, providing high-precision, high-reliability position signals for servo control systems.

[0096] The servo control circuit consists of both software and hardware. The software functions mainly include three-loop control, speed and position calculation, correction network, vector transformation, SVPWM space vector control, serial communication, and fault handling. The three-loop control comprises a position loop, a speed loop, and a current loop. The hardware consists of a control circuit, a drive circuit, and a detection circuit. The control circuit, including the DSP minimum system, the FPGA minimum system, and the human-machine interface circuit, is the core of the entire servo control circuit. The drive circuit consists of a pulse shaping circuit and an inverter circuit. The pulse shaping circuit filters out high-order harmonics generated in the rectifier circuit, and the inverter circuit performs DC-AC inversion to drive the torque motor. The detection circuit consists of fault detection, current detection, and position and speed detection circuits. The fault signal is connected to the DSP's power protection interrupt pin PDPINTA. When a fault occurs, the DSP cuts off the PWM output and enters a protection state. The current detection circuit uses a three-resistor sampling mode to detect the three-phase current of the motor. The position and speed detection circuit receives position signals from the angle encoder to obtain the accurate position of the motor rotor.

[0097] Specifically, this embodiment provides a servo control system for a gyro accelerometer, including an inductive encoder 1, a permanent magnet synchronous torque motor 2, an inner ring angle sensor 3, a servo control circuit 4, an inner ring 5 of the gyro accelerometer, and an outer ring 6 of the gyro accelerometer. The inductive encoder 1 comprises a flat ring stator and a rotor, which are coaxially mounted with the permanent magnet synchronous torque motor 2. Its stator has an SSI interface to output a natural binary code position signal. The permanent magnet synchronous torque motor 2 adopts permanent magnet synchronous torque, and the relative air gap permeability and the air gap magnetic flux density of the permanent magnet are optimized in the design of the motor body to effectively suppress torque pulsation structurally. The inner ring angle sensor 3 is used to measure the rotation angle β of the inner ring 5 of the gyro accelerometer relative to the outer ring 6 of the gyro accelerometer. The FPGA circuit in the servo control circuit 4 receives the position signal from the angle encoder 1 and calculates the rotor speed (n) and position (θ) of the torque motor through the speed and position calculation module, providing the real-time absolute position and speed of the motor rotor for the servo control loop. After receiving the position and speed information of the motor rotor, the DSP main control program in the servo control circuit 4 adjusts the three closed-loop regulators and outputs the modulated PWM signal through the SVPWM module to the drive circuit to control the permanent magnet synchronous torque motor 2 to work.

[0098] As one of the core inertial instruments in an inertial navigation system, the gyro accelerometer needs to improve in areas such as angle encoder accuracy, servo control loop design, and low-speed smooth control performance of the torque motor to achieve high measurement accuracy. Figure 1 This is a general functional block diagram of a servo control system on a gyro accelerometer, including an inductive encoder 1, a permanent magnet synchronous torque motor 2, an inner ring angle sensor 3, a servo control circuit 4, an inner ring of the gyro accelerometer 5, and an outer ring of the gyro accelerometer 6.

[0099] In this embodiment, the inductive encoder 1 of the servo control system on a gyroscope accelerometer is an inductive absolute angle encoder, powered by +5VDC. It transmits binary code signals containing position and rotational speed to the FPGA chip in the servo control circuit 2 via the SSI interface protocol. The external wiring of the inductive encoder 1 includes a pair of power lines, a pair of synchronous clock differential signals (SCLK_A, SCLK_B), a pair of serial data differential signals (SD_A, SD_B), a zero-position setting signal (Zero), and a direction setting signal (DIR), totaling eight wires. The zero-position setting signal is high by default; the encoder resets on the falling edge and sets the current angle to zero. The direction setting signal is high by default; the direction of data increment is switched on the falling edge. The SSI interface circuit between the angle encoder and the FPGA chip includes a transceiver chip, a high-speed optocoupler, and an isolation power supply. The transceiver chip uses the low-power MAX485 chip for half-duplex communication. To ensure the real-time performance of the clock and data differential signals, this invention uses one MAX485 chip for each of the SCLK clock signal and SD data signal, achieving stable and reliable real-time acquisition. An optocoupler circuit isolates the SCLK signal from the SD data signal and simultaneously performs 3.3V to 5V level conversion.

[0100] The FPGA chip used is a Xilinx Virtex-6 series chip, with a sampling clock period set to 10µs. Following the SSI protocol's requirement of a high level idle clock and falling edge sampling, the SPI is configured to operate in mode 2. In this invention, one frame of SD serial data is 32 bits, including 22 bits of angle encoder data. The encoder outputs an absolute position every 1ms. To ensure correct data acquisition, the FPGA first stores the received data in a buffer register, and then performs a CRC check on the 32-bit buffered data after reception. Once the data is deemed valid, it is unpacked, and the 22 valid data bits are stored in the valid data register. The FPGA's internal position calculation module calculates the data to obtain the rotor's absolute position information, and the speed calculation module calculates the speed based on time and position changes.

[0101] The main control chip of the DSP control circuit uses the TI TMS320F28335 dedicated motor digital control chip, with an operating voltage of 3.3V. After receiving the position and speed information sent by the FPGA via SPI communication, the DSP selects whether to introduce a position regulator based on the working state settings of the gyroscope accelerometer. The speed regulator calculates the target current based on the tracking speed provided by the calibration network or the target speed provided by the position regulator. The current regulator and SVPWM module generate a PWM control signal, which is then filtered and level-converted by the pulse shaping circuit. Finally, the ADUM3223 driver chip in the drive circuit generates a drive signal to control the power device to conduct, thereby controlling the torque motor to work. The torque motor is a permanent magnet synchronous torque motor, controlled by a rotating vector (FOC) control algorithm and a three-loop control system, which makes the control process more stable and precise, effectively improving the ability to suppress torque ripple and low-speed smooth performance, and achieving precise compensation for external friction torque.

[0102] Figure 2 The servo control circuit 4 mainly consists of the following parts: a speed and position detection module, a position regulator, a speed regulator, a current regulator, a coordinate transformation module, an SVPWM module, and a decoupling control module. The position regulator compares the motor rotor position signal output from the speed and position detection module with the given θ. ref The comparison is performed, and the result is used as the input reference value n for the speed regulator. ref The speed regulator outputs the speed n and n' based on the speed and position detection module. ref Compare and output the quadrature-axis current reference value I. qref As the input to the current regulator, the stator current I collected by the current sensor. a I b I c The α and β axis currents I in the stationary coordinate system are obtained by transforming to a two-phase stationary coordinate system using Clark transformation. α I β Then, by Park transformation to a two-phase rotating coordinate system, the direct-axis current I is obtained. d and quadrature axis current I q I d and I q The reference value I of the quadrature-axis current given by the current regulator is respectively qref and direct-axis given current I dref By comparison, the direct-axis voltage U is obtained. d With cross-axis voltage U q Performing the inverse Park transformation on both yields the α- and β-axis voltages U in the stationary coordinate system. α U βFinally, the inverter is driven by the output of 6 variable duty cycle PWM signals through the SVPWM module, which outputs a three-phase sinusoidal current with variable amplitude and frequency to achieve stable control of the torque motor.

[0103] Figure 3 This is the flowchart of the motor control interrupt subroutine. The main tasks of this subroutine are to acquire rotor position and speed, estimate dq-axis current, adjust the regulator, perform coordinate transformation, apply the SVPWM algorithm, and compensate for dead time. The interrupt clock frequency is 12.5 kHz, and the interrupt period is 2 ms (80 μs * 25 = 2 ms). Each period completes one current loop operation to obtain the updated quadrature-axis current I. q This program adopts a single-sample, single-update design. The interrupt execution frequency is consistent with the AD sampling frequency, the PWM duty cycle activation frequency, and the switching frequency. Therefore, the SVPWM algorithm module will update the I... q A PWM signal with the corresponding duty cycle is generated to control the MOSFET, completing one motor control cycle. The regulator includes a position regulator (outer loop regulator), a speed regulator (middle loop regulator), and an inner loop regulator (inner loop), collectively referred to as a three-loop regulator, all employing PID control algorithms. During the design of the three-loop regulators, considering that sudden changes in the controller output value due to sudden input or operating conditions could lead to stator overvoltage or overcurrent, an integral limiting circuit is added to prevent overshoot or misalignment caused by a slower system settling time. Simultaneously, to improve system output stability and prevent frequent system movements near the target value, which could cause motor output torque fluctuations and affect the accuracy of the gyroscope accelerometer, all three-loop regulators have a closed-loop dead zone. The control flow of the position regulator with integral limiting and closed-loop dead zone is as follows: Figure 4 As shown, after the position regulator obtains the real-time rotor position information from the feedback, it first compares it with the target position information. Adjustment will only be performed if the deviation is greater than a set threshold. After completing the closed-loop dead zone judgment, the position deviation is compared with the integral limiting threshold. If it exceeds the limiting threshold, the integral element is separated, and only the PI algorithm is used for adjustment.

[0104] The speed regulator incorporates a segmented output control method in its design. The specific method is as follows:

[0105] Different PI parameters are used based on the absolute value of the speed deviation, dividing the process into coarse adjustment, fine adjustment, and micro-adjustment zones. The coarse adjustment zone uses a large P parameter and a small I parameter to quickly reduce the error; the fine adjustment zone uses medium P and I parameters to achieve a smooth transition, ensuring speed while preventing overshoot; the micro-adjustment zone uses a small P parameter and a large I parameter to achieve fine adjustment, eliminate steady-state error, avoid oscillation, and improve steady-state accuracy.

[0106] The deviation between the real-time speed information fed back by the inductive encoder and the target speed is set into segmented intervals. The speed deviation is related to the quadrature-axis reference current I output by the speed regulator. ref Proportional to the actual rotational speed; when the actual rotational speed is much smaller than the target rotational speed, the output quadrature-axis reference current I is increased. ref The SVPWM module outputs a high duty cycle PWM signal; as it approaches the target speed, it outputs a quadrature-axis reference current I. ref The duty cycle of the SVPWM module's output PWM signal is relatively small. This approach can quickly balance the outer ring friction torque of the gyroscope accelerometer while effectively reducing motor output torque fluctuations.

[0107] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

[0108] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A gyroscope accelerometer servo control system based on a permanent magnet synchronous torque motor, characterized in that, Includes: an inductive encoder (1), a permanent magnet synchronous torque motor (2), an inner ring angle sensor (3), a servo control circuit (4), an inner ring of a gyro accelerometer (5), and an outer ring of a gyro accelerometer (6); among which, The outer ring (6) of the gyro accelerometer obtains the real-time absolute position and real-time speed of the rotor of the permanent magnet synchronous torque motor (2); The inductive encoder (1) sends the real-time absolute position obtained from the outer ring (6) of the gyroscope accelerometer to the servo control circuit (4); The permanent magnet synchronous torque motor (2) generates torque under the action of the three-phase current output by the servo control circuit (4), drives the rotor to rotate, and drives the outer ring (6) of the gyroscope accelerometer to rotate. The inner ring angle sensor (3) is used to measure the inner ring angle of the inner ring (5) of the gyro accelerometer and output it to the servo control circuit (4); The servo control circuit (4) receives the real-time absolute position provided by the inductive encoder (1), calculates the current absolute position, and calculates the real-time rotational speed based on the position difference between the current absolute position and the absolute position at the previous moment. At the same time, it receives the inner ring angle provided by the inner ring angle sensor (3), and after calculation by the position ring, speed ring and current ring, it outputs the SVPWM drive signal to adjust the magnitude and direction of the three-phase current acting on the permanent magnet synchronous torque motor (2) to achieve dynamic balance of the interference torque of the outer ring (6) of the gyro accelerometer, so that the angle of the inner ring (5) of the gyro accelerometer is stabilized near the zero position.

2. The gyroscope accelerometer servo control system based on a permanent magnet synchronous torque motor as described in claim 1, characterized in that, The inductive encoder (1) has a resolution of 22 bits, outputs absolute position, outputs data via SSI interface, outputs one absolute position with a period of 1ms, and is powered by +5V DC voltage.

3. The gyroscope accelerometer servo control system based on a permanent magnet synchronous torque motor as described in claim 1, characterized in that, The stator and rotor of the inductive encoder (1) are designed separately. The power supply and data transmission wires are led out on one side of the stator. The rotor has no transmission wires and is coaxially mounted with the rotor of the permanent magnet synchronous torque motor (2) and installed on the outer ring (6) of the gyroscope accelerometer.

4. The gyroscope accelerometer servo control system based on a permanent magnet synchronous torque motor as described in claim 1, characterized in that, The servo control circuit (4) includes a control circuit, a drive circuit, and a detection circuit; wherein, The control circuit generates a PWM control signal based on the collected data sent by the detection circuit and sends it to the drive circuit. The drive circuit controls the permanent magnet synchronous torque motor (2) to work according to the PWM control signal sent by the control circuit; The detection circuit collects the three-phase voltage, current and fault signals of the permanent magnet synchronous torque motor (2) and provides them to the control circuit.

5. A gyroscope accelerometer servo control system based on a permanent magnet synchronous torque motor as described in claim 4, characterized in that, The control circuit includes a three-closed-loop control module, a correction network, a speed and position calculation module, an SVPWM space vector control module, an inverter circuit, a serial communication module, and a fault handling module. The three-loop control module, based on the motor rotor position signal output by the speed and position calculation module, uses integral limiting and closed-loop dead zone setting to adjust position, speed, and current, and outputs the α and β axis voltages U in the stationary coordinate system. α U β Provide the SVPWM space vector control module; The rotation speed and position calculation module is located in the FPGA chip of the control circuit. It verifies and calculates the real-time absolute position sent by the inductive encoder (1) and provides real-time position information to the DSP chip of the control circuit. The correction network corrects the inner ring angle collected by the inner ring angle sensor to provide a target rotational speed for the speed ring; The SVPWM space vector control module controls the α and β axis voltages U in the stationary coordinate system. α U β After sector determination and dead-time compensation, six PWM drive signals are output to the inverter circuit. The inverter circuit converts the 6-channel PWM drive signals into a three-phase sinusoidal current and outputs it to the permanent magnet synchronous torque motor (2); The serial communication module enables data communication between modules and the burning of control programs. The fault handling module performs overvoltage protection, overcurrent protection, and overload protection, and triggers protection actions and provides fault information when a fault is detected.

6. The gyroscope accelerometer servo control system based on a permanent magnet synchronous torque motor as described in claim 5, characterized in that, The three-closed-loop control module includes a position regulator, a speed regulator, and a current regulator; wherein, The position regulator compares the motor rotor position signal output by the speed and position calculation module with the given target position to obtain the speed reference value, which is then output to the speed regulator. The speed regulator compares the rotational speed output from the rotational speed and position calculation module with a speed reference value, and outputs a quadrature-axis current reference value I. qref Send it to the current regulator; The current regulator, based on the stator current output by the inverter, obtains the voltage through coordinate transformation and comparison with the set value, and outputs it to the SVPWM space vector control module.

7. A gyroscope accelerometer servo control system based on a permanent magnet synchronous torque motor as described in claim 6, characterized in that, The voltage is obtained by transforming the coordinates and comparing it with a set value based on the stator current output by the inverter, specifically as follows: Based on the stator current I output by the inverter a I b I c By transforming to a two-phase stationary coordinate system using Clark transformation, the α-axis and β-axis currents I in the stationary coordinate system are obtained. α I β Then, by performing a Park transformation to a two-phase rotating coordinate system, the direct-axis current I is obtained. d and quadrature axis current I q ; Direct-axis current I d and quadrature axis current I q The cross-axis current reference value I sent by the current regulator is respectively compared with the reference value I. qref and direct-axis given current I dref By comparison, the direct-axis voltage U is obtained. d With cross-axis voltage U q ; The direct-axis voltage U d With cross-axis voltage U q Perform the inverse Park transformation to obtain the voltages U along the α and β axes in the stationary coordinate system. α U β .

8. A gyroscope accelerometer servo control system based on a permanent magnet synchronous torque motor as described in claim 5, characterized in that, The adoption of integral limiting and closed-loop dead zone settings is specifically as follows: S11, The position regulator obtains the real-time position information of the rotor from feedback; S12. Determine whether the deviation between the real-time rotor position information and the target position information is greater than the set dead zone threshold; if so, proceed directly to step S13. Otherwise, clear the PID parameters and exit; S13. Determine whether the deviation between the real-time rotor position information and the target position information is less than the integral limiting threshold. If so, PID control is performed; otherwise, PD control is performed first, followed by PID control. Finally, the PID position controller outputs the speed reference value and sends it to the speed controller.

9. A gyroscope accelerometer servo control system based on a permanent magnet synchronous torque motor as described in claim 5, characterized in that, The speed regulator adopts segmented interval control, specifically: the deviation between the real-time speed information fed back by the encoder and the target speed is segmented; the control interval is divided into coarse adjustment interval, fine adjustment interval and micro adjustment interval according to the magnitude of the absolute value of the speed deviation; the speed controller uses different PI parameters for different control intervals.

10. A gyroscope accelerometer servo control system based on a permanent magnet synchronous torque motor as described in claim 1, characterized in that, The permanent magnet synchronous torque motor (2) can generate a maximum torque of 2400 gf.cm.

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