Circuit module for demodulating rotary transformer

Abstract

The invention relates to a circuit module for demodulating a rotary transformer, and belongs to the field of servo mechanism rotary transformer angular position signal measurement. The STM32F407 main control circuit analyzes the rotary transformer signal test instruction to generate a rotary transformer measurement starting instruction, sends the rotary transformer measurement starting instruction to the AD2S1210 decoding and buffering circuit, generates a sine wave excitation signal and sends the sine wave excitation signal to an external rotary transformer; when an external servo system drives a load table to swing, a rotating shaft of the rotary transformer rotates, and sine wave signals and cosine wave signals are sensed; the AD2S1210 decoding and buffering circuit converts the sine wave signal and the cosine wave signal into digital quantities corresponding to the shaft angle and the speed, and the digital quantities are sent to an external upper computer PC end through the STM32F407 main control circuit; the rotary transformer is adopted to replace a slide rheostat, zero setting is not needed for outputting absolute signals, precision and reliability are improved, customization cost is reduced, anti-interference capacity is improved, Ethernet and USB interfaces are expanded, and networking and digital application are achieved.

Description

Technical Field

[0001] This invention belongs to the field of angular position signal measurement of servo mechanism rotary transformers, and relates to a rotary transformer demodulation circuit module. Background Technology

[0002] In modern industrial control, the demands for position detection accuracy and real-time performance are becoming increasingly stringent. Commonly used angular position sensing elements include optical encoders, magnetic encoders, and rotary transformers. Due to manufacturing and precision limitations, magnetic encoders are not as widely used as the other two. Optical encoders output pulse signals, which are inherently digital and easy to process, thus enjoying widespread application. However, optical encoders are highly dependent on motor parameters and have weak anti-interference capabilities, making them unsuitable for harsh conditions, thus limiting their application.

[0003] Currently, rotary transformers have become a core tool for high-precision angle measurement in servo systems, and their performance directly affects the control quality of the servo system. Early rotary transformers were limited in application due to their complex signal processing circuits and high cost. However, their unparalleled reliability and sufficiently high precision make them irreplaceable in many situations.

[0004] In their article "Design of Resolver Decoding Circuit Based on AD2S1210" (Infrared Technology, December 2016, Vol. 38, No. 12), Liu Yunyi et al. introduced a sensor decoding circuit for position detection in a step-gazing scanning imaging platform. The decoding circuit utilizes the resolver-to-digital converter (RDC) chip AD2S1210 to decode the resolver J78XFS009. The decoding circuit includes the AD2S1210's operating principle circuit, peripheral circuits, and the connection circuit between the chip and the microcontroller and resolver. The entire circuit has a simple structure, high reliability, good stability, high accuracy, and strong anti-interference capabilities, enabling it to operate in harsh environments and possessing high practical value. The main control chip of this circuit uses Microchip Technology's DSC (Digital Signal Controller), with a THS4062 high-speed operational amplifier forming a buffer circuit. The system is mainly used to detect the motor's position signal and realize multi-closed-loop control of the motor; it is not applied to the measurement of load platform angular displacement signals.

[0005] The invention patent "A Fully Automatic Angular Displacement Sensor Testing Device", application publication number: "CN117870595A, 718 Research Institute of China Shipbuilding Group Corporation, 2024-01-15", discloses a fully automatic angular displacement sensor testing device. This device controls the angular displacement sensor to rotate at a predetermined angle using a high-precision harmonic reducer. The sine and cosine analog voltage signals output by the angular displacement sensor are uploaded to an industrial control computer via a signal acquisition board. The industrial control computer performs data processing on the input digital signals and displays the measured data of the angular displacement sensor on a monitor, thereby determining whether the sensor performance meets the requirements. The signal acquisition board uses the AD2S1210 resolver decoding chip and employs a two-stage signal conditioning circuit to achieve high-speed acquisition and processing of the angular displacement sensor's output voltage signal. This patent is a system integration design scheme and does not disclose the specific implementation method of the resolver decoding circuit.

[0006] The following problems exist in the testing of existing electromechanical servo mechanism load tables: 1. Traditional sliding rheostat angular displacement sensors suffer from low accuracy, short lifespan, and the need for manual zeroing. 2. Custom-made resolver decoding circuits are costly and lack standardized interfaces. 3. The resolver signal decoding process is susceptible to common-mode / differential-mode interference, leading to decreased measurement accuracy. 4. The lack of digital communication interfaces (Ethernet / USB) in servo system testing equipment results in poor system compatibility. Summary of the Invention

[0007] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a rotary transformer demodulation circuit module. By using a rotary transformer to replace the sliding rheostat, the output absolute signal does not require zeroing, thereby improving accuracy and reliability, reducing customization costs and improving anti-interference capabilities, and expanding Ethernet and USB interfaces, it realizes networking and digital applications.

[0008] The solution of the present invention is:

[0009] A resolver demodulation circuit module, characterized in that it includes an AD2S1210 decoding and buffering circuit, a resolver signal filtering circuit, and an STM32F407 main control circuit;

[0010] The STM32F407 main control circuit receives resolver signal test commands from an external host PC; after parsing the resolver signal test commands, it generates a resolver measurement start command; and sends the resolver measurement start command to the AD2S1210 decoding and buffering circuit; it receives the digital values ​​corresponding to the shaft angle and speed from the AD2S1210 decoding and buffering circuit, and sends the digital values ​​corresponding to the shaft angle and speed to the external host PC, completing the acquisition and demodulation of the resolver signal.

[0011] The AD2S1210 decoding and buffering circuit receives the resolver measurement start command from the STM32F407 main control circuit, generates a sinusoidal excitation signal, and sends the sinusoidal excitation signal to the external resolver; it also receives the filtered sinusoidal and cosine signals from the resolver signal filtering circuit, converts them into digital quantities corresponding to the shaft angle and speed, and sends the digital quantities corresponding to the shaft angle and speed to the STM32F407 main control circuit.

[0012] External rotary transformer: Receives the sinusoidal excitation signal from the AD2S1210 decoding and buffering circuit to start up; when the external servo system drives the load platform to swing, the rotary transformer shaft rotates, inducing sine wave and cosine wave signals; and sends the sine wave and cosine wave signals to the rotary transformer signal filtering circuit;

[0013] Resolver signal filtering circuit: Receives sine wave and cosine wave signals from an external resolver, filters the sine wave and cosine wave signals, and then forwards them to the AD2S1210 decoding and buffering circuit.

[0014] In the aforementioned resolver decoding circuit module, the AD2S1210 decoding and buffer circuit includes a resolver-to-digital converter (U1), a passive crystal oscillator (U2), a load capacitor (C1), a load capacitor (C2), a filter capacitor (C30), a filter capacitor (C29), a filter capacitor (C31), a damping array (RN1), a damping array (RN2), a damping array (RN3), an operational amplifier (U3), a crossover bias diode (D1), a crossover bias diode (D2), resistors (R1, R2, R3, R4, R5), and an electrical... Resistors R6, R7, R8, R9, R10, R11, R12, R13, R14, R15, and R16; filter capacitor C3; filter capacitor C4; transistors Q1, Q2, Q3, and Q4; and a working mode selection circuit; wherein the working mode selection circuit includes resistors R28, R29, R30, R31, and R32; and slide switches U9 and U10.

[0015] Specifically, the RSE1 pin of chip U1 is connected to point 2 of the U9 slide switch; the RSE0 pin is connected to point 2 of the U10 slide switch; the NCS pin is the chip select signal, connected to resistor R29 and then to GND; in serial input mode, NCS remains low, and the NRD pin is connected to resistor R31 (pull-up resistor) and then to the external logic power signal VDRIVER; in serial input mode, the NRD pin remains high; the NFSYNC pin is connected to the RN1 damping bus and then to the STM32F407 main control circuit to implement edge logic input; the DGND pin is connected to signal ground; the DVDD pin is connected to the external 5V digital power supply; the CLKIN pin is connected to the output of the U2 passive crystal oscillator and also to one end of the C1 load capacitor; the other end of C1 is connected to signal ground; the XTALOUT pin is connected to the output of the U2 passive crystal oscillator and... The NSOE pin is connected to one end of the load capacitor C2; the other end of C2 is connected to signal ground; the NSOE pin is connected to one end of resistor R32; the other end of resistor R32 is connected to signal ground; NOSE is in serial input mode when set to low level; the SAMPLE pin is connected to the RN3 damping bus and then to the STM32F407 master control circuit to realize external sampling result judgment; the SDO pin is connected to the RN3 damping bus and then to the STM32F407 master control circuit for SPI2 bus slave device data output; the SDI pin is connected to the RN3 damping bus and then to the STM32F407 master control circuit for SPI2 bus slave device data input; the SCLK pin is connected to the RN3 damping bus and then to the STM32F407 master control circuit for the SPI2 bus clock signal; the VDRIVER pin is the external logic power supply connected to external 3.3V power supply; DGND pin connected to signal ground; Pin A connected to RN2 damping bus for external monitoring of incremental encoder simulation output A; Pin A connected to RN2 damping bus for external monitoring of incremental encoder simulation output B; NIM pin connected to RN2 damping bus for external monitoring of North Marker incremental encoder simulation output; DIR pin connected to RN2 damping bus for external monitoring of the direction of the resolver; RESET# pin connected to RN1 damping bus for connection to the STM32F407 main control circuit for reset enable signal; LOT pin connected to external LED indicator for tracking loss fault indication; DOS pin connected to external LED indicator for signal degradation fault indication; A1 pin connected to RN1 damping bus for connection to the STM32F407 main control circuit for mode selection 1; A0 pin connected to RN1 damping bus for connection to the STM32F407 main control circuit for mode selection 0; EXC pin connected to R14. One end of the resistor is used for the high-side input of the excitation signal; the EXC# pin is connected to one end of resistor R15 for the low-side input of the excitation signal; the AGND pin is connected to signal ground; the SIN pin is connected to the resolver signal filter circuit; the SINLO pin is connected to the resolver signal filter circuit; the AVDD pin is connected to an external analog 5V power supply; the COSLO pin is connected to the resolver signal filter circuit; the COS pin is connected to the resolver signal filter circuit; the REFBYP pin is connected to one end of both filter capacitors C30 and C31, and the other ends of filter capacitors C30 and C31 are connected to signal ground; the REFOUT pin is connected to one end of filter capacitor C29, and the other end of filter capacitor C29 is connected to signal ground.

[0016] EXC, the excitation signal, is connected to one end of the input resistor R14. The other end of the input resistor R14 is connected to the feedback resistor R13, and the other end of the feedback resistor R13 is connected to the inverting input of channel A of op-amp U3. Simultaneously, resistor R13 is connected in parallel with filter capacitor C3 and marked with the EXC+ signal. The EXC+ signal is connected between resistors R9 and R10. Resistor R9 is connected to the emitter of transistor Q1, and the base of transistor Q1 is connected between resistors R1 and R5. Resistor R5 is pulled up to the external power supply VCC+12. Resistor R1 is connected to bidirectional diode D1 and then connected to the output of channel A of op-amp U3. Resistor R10 is connected to the collector of transistor Q3, and the base of transistor Q3 is connected between resistors R2 and R6. Resistor R2 is connected to bidirectional diode D1 and then connected to the output of channel A of op-amp U3. The emitter of transistor Q3 is connected to analog ground AGND, and resistor R6 is also connected to analog ground AGND. EXC+, as the excitation amplification signal, is connected to the primary winding R1 of the rotary transformer's excitation terminal.

[0017] NEXC is the low end of the excitation signal. It is connected to the EXC- signal in the same way as the EXC signal through transistors Q2 and Q4, resistors R3, R4, R7, R8, R11, R12, R15, R16, capacitor C4, and bidirectional diode D2. EXC- is connected to the resolver as the low end of the excitation amplification signal.

[0018] The external logic power signal VDRIVER is connected to resistor R28 and outputs the H_V signal, which is then connected to point 1 of slide switches U9 and U10. The L_V signal is connected to point 3 of slide switches U9 and U10 after passing through resistor R30. Different resolution code values ​​are set for pins RES1 and RES0 of chip U1 by selecting different gears. The NCS signal is grounded through resistor R29 to enable the NCS signal at a low level. The NSOE signal is grounded through resistor R32 to enable the NSOE signal at a low level in serial input mode. The external logic power signal VDRIVER is connected to resistor R31 to set the NRD signal to a high level in serial input mode.

[0019] In the aforementioned rotary transformer decompression circuit module, the external rotary transformer is provided with two primary windings and four secondary windings, namely primary winding M1, primary winding M2, secondary winding S1, secondary winding S2, secondary winding S3, and secondary winding S4.

[0020] After the AD2S1210 decoding and buffer circuit outputs a sinusoidal excitation signal, the sinusoidal excitation signal generated between the EXC pin and the other pin is connected to the primary windings R1 and R2 of the rotary transformer through the buffer circuit. When the external servo system drives the load platform to swing, the rotary transformer shaft rotates. The two staggered secondary windings S1 and S3 on the shaft stator induce sinusoidal signals, which are connected to the SIN and SINLO pins through the filter circuit. The secondary windings S2 and S4 induce cosine signals, which are connected to the COS and COSLO pins through the filter circuit. The signals then enter the AD2S1210 decoding and buffer circuit again, and after internal conversion, obtain the digital signals corresponding to the shaft angle and speed.

[0021] In the aforementioned resolver demodulation circuit module, the resolver signal filtering circuit includes a U8 terminal block, L4 common-mode inductor, L5 common-mode inductor, L6 differential-mode inductor, L7 differential-mode inductor, L8 differential-mode inductor, L9 differential-mode inductor, C32 capacitor, C33 capacitor, C34 capacitor, C35 capacitor, C36 capacitor, C37 capacitor, resistor R113, and resistor R114.

[0022] The SIN+ pin of terminal U8 is the high end of the sinusoidal signal output from the resolver, connected to the input of the first winding of the L4 common-mode inductor. The output of the first winding of L4 is connected to the input of the L6 differential-mode inductor. The output of the L6 differential-mode inductor is connected to one end of the C32 differential-mode capacitor, one end of the R113 damping resistor, and one end of the C33 common-mode capacitor, outputting the SIN1+ signal to the SIN1+ pin of the U1 chip. The SIN- pin of terminal U8 is the low end of the sinusoidal signal output from the resolver, connected to the input of the second winding of the L4 common-mode inductor. The output of the second winding of L4 is connected to the input of the L7 differential-mode inductor. The output of the L7 differential-mode inductor is connected to the other end of the C32 differential-mode capacitor, the other end of the R113 damping resistor, and one end of the C34 common-mode capacitor, outputting the SIN1- signal to the SIN1- pin of the U1 chip. The other ends of the C33 and C34 common-mode capacitors are connected to the signal... Ground; The COS+ pin of terminal U8 is the high end of the cosine signal output from the rotary transformer, connected to the input terminal of the first winding of the L5 common-mode inductor. The output terminal of the first winding of L5 is connected to the input terminal of the L8 differential-mode inductor. The output terminal of the L8 differential-mode inductor is connected to one end of the C35 differential-mode capacitor, one end of the R114 damping resistor, and one end of the C36 common-mode capacitor, then outputting the COS1+ signal to the COS1+ pin of the U1 chip; The COS- pin of terminal U8 is the low end of the cosine signal output from the rotary transformer, connected to the input terminal of the second winding of the L5 common-mode inductor. The output terminal of the second winding of L5 is connected to the input terminal of the L9 differential-mode inductor. The output terminal of the L9 differential-mode inductor is connected to the other end of the C35 differential-mode capacitor, one end of the R114 damping resistor, and one end of the C37 common-mode capacitor, then outputting the COS1- signal to the COS1- pin of the U1 chip; The other ends of the C36 and C37 common-mode capacitors are connected to signal ground.

[0023] In the aforementioned rotary transformer demodulation circuit module, the STM32F407 main control circuit includes a U11 main control chip STM32F407 microcontroller, a U10 Ethernet interface chip W5500, an RN6 damping resistor array, and an RJ1 Ethernet transformer.

[0024] Specifically, pin PB13 of the U11 chip is connected to pin SCLKS of the RN3 damping resistor array for the SPI2 bus clock signal; pin PB14 is connected to pin SDOS of the RN3 damping resistor array for SPI2 bus slave data output; pin PB15 is connected to pin SDIS of the RN3 damping resistor array for SPI2 bus slave data input; pin PD8 is connected to pin SAMS of the RN3 damping resistor array for external sampling result judgment; pin PA11 of the U11 chip is connected to one end of resistor R111; the other end of resistor R111 is connected to pin 1 of USB1; pin PA12 of the U11 chip is connected to one end of resistor R112; the other end of resistor R112 is connected to pin 2 of USB1; pin PB3 of the U11 chip is connected to pin SCLK of the U10 chip for the SPI1 bus clock. Signals; PB4 pin is connected to the U10 chip's MISO pin for SPI1 bus master input / slave output; PB5 pin is connected to the U10 chip's MOSI pin for SPI1 bus master output / slave input; PB8 pin is connected to the U10 chip's RSTN pin for SPI1 bus reset signal; PB9 pin is connected to the U10 chip's INTN pin for SPI1 bus interrupt signal; PA15 pin is connected to the U10 chip's SCAN pin for SPI1 bus chip select signal; U10 chip's TXN, TXP, RXN, and RXP pins are connected to the input terminals of the RN6 damping resistor array; the output terminals of the RN6 damping resistor array are respectively connected to the TD-, TD+, RD+, and RD- pins of the RJ1 Ethernet transformer for Ethernet transmit signal low end, transmit signal high end, receive signal high end, and receive signal low end.

[0025] In the aforementioned resolver demodulation circuit module, the external host PC sends resolver signal test commands to the STM32F407 main control circuit via an Ethernet TCP / IP protocol interface or a USB 2.0 interface. After parsing the resolver signal test commands into resolver measurement start commands, the STM32F407 main control circuit sends the resolver measurement start commands to the AD2S1210 decoding and buffering circuit via the SPI2 serial peripheral device interface.

[0026] In the aforementioned rotary transformer demodulation circuit module, the AD2S1210 decoding and buffering circuit sends the digital quantities corresponding to the shaft angle and speed to the STM32F407 main control circuit through the SPI2 serial peripheral device interface; the STM32F407 main control circuit sends the digital quantities corresponding to the shaft angle and speed to the external host PC through the Ethernet TCP / IP protocol interface or USB2.0 interface.

[0027] In the aforementioned rotary transformer demodulation circuit module, the SPI2 serial peripheral device interface is:

[0028] The NSOE pin is kept low to select this serial interface. The serial interface of the AD2S1210 decoding and buffering circuit consists of four signals: SDO, SDI, WR / FSYNC, and SCLK. SDI is used to transfer data to the on-chip registers, and SDO is used to retrieve data from the on-chip registers, including position, speed, and fault registers. SCLK is the device's serial clock input, and all data transfers are performed relative to this SCLK signal. WR / FSYNC is used for frame synchronization data. The falling edge of WR / FSYNC takes the SDI and SDO lines out of the high-impedance state, and the rising edge of WR / FSYNC returns the SDI and SDO lines to the high-impedance state. The serial interface does not require a CS input; CS is kept low.

[0029] In the aforementioned rotary transformer demodulation circuit module, the SDO output process is as follows:

[0030] In normal operating mode, data is shifted out of the device as a 24-bit word under the control of the serial clock input SCLK; data is shifted out on the rising edge of SCLK.

[0031] In the aforementioned rotary transformer demodulation circuit module, the SDI input process is as follows:

[0032] In configuration mode, it addresses on-chip registers and is used as daisy-chain inputs; data is shifted into the device on the falling edge of SCLK.

[0033] The beneficial effects of this invention compared to the prior art are:

[0034] (1) This invention proposes a rotary transformer to replace the sliding rheostat sensor, which solves the problems of low accuracy, slow dynamic response and frequent zeroing required in the test of the load stage angular displacement of electromechanical servo mechanism, and significantly improves the test efficiency and environmental adaptability of servo mechanism.

[0035] (2) Based on the AD2S1210 chip, the present invention achieves a maximum resolution of 16 bits, with data jump bits ≤ 2LSB, and a tracking rate of 3125rps at 10-bit resolution, which meets the requirements of high-precision angular position measurement.

[0036] (3) The two-stage push-pull buffer circuit (high-precision operational amplifier + power amplifier) ​​of the present invention replaces the traditional single-stage amplification, reduces signal distortion, and ensures that the excitation signal (3.2-4.0V pp) is stably transmitted to the resolver sensor;

[0037] (4) This invention integrates Ethernet (10 / 100M) and USB2.0 interfaces, supports flexible communication with the host computer, and adapts to diverse industrial control scenario requirements. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the rotary transformer decompression circuit module of the present invention;

[0039] Figure 2 This is a schematic diagram of the AD2S1210 decoding and buffering circuit of the present invention;

[0040] Figure 3 This is a schematic diagram showing the connection between the AD2S1210 of the present invention and a rotary transformer;

[0041] Figure 4 This is a schematic diagram of the resolver signal filtering circuit of the present invention;

[0042] Figure 5 This is a schematic diagram of the STM32F407 main control circuit of the present invention;

[0043] Figure 6 This is a timing diagram of the SPI2 serial interface of the present invention. Detailed Implementation

[0044] The present invention will be further described below with reference to the embodiments.

[0045] This invention provides a rotary transformer demodulation circuit module that uses a rotary transformer to replace a sliding rheostat, outputting an absolute signal without zeroing, improving accuracy and reliability, reducing customization costs and enhancing anti-interference capabilities, and expanding Ethernet and USB interfaces to realize networking and digital applications.

[0046] Rotary transformer decomposition circuit module, such as Figure 1 As shown, the circuit specifically includes an AD2S1210 decoding and buffering circuit, a resolver signal filtering circuit, and an STM32F407 main control circuit. The STM32F407 main control circuit: receives resolver signal test commands from an external host PC; parses the resolver signal test commands and generates a resolver measurement start command; sends the resolver measurement start command to the AD2S1210 decoding and buffering circuit; receives the digital values ​​corresponding to the shaft angle and speed from the AD2S1210 decoding and buffering circuit, and sends these digital values ​​to the external host PC, completing the acquisition and demodulation of the resolver signal.

[0047] The AD2S1210 decoding and buffering circuit receives the resolver measurement start command from the STM32F407 main control circuit, generates a sinusoidal excitation signal, and sends the sinusoidal excitation signal to the external resolver; it receives the filtered sinusoidal and cosine signals from the resolver signal filtering circuit, converts them into digital quantities corresponding to the shaft angle and speed, and sends the digital quantities corresponding to the shaft angle and speed to the STM32F407 main control circuit.

[0048] External rotary transformer: Receives the sinusoidal excitation signal from the AD2S1210 decoding and buffering circuit to start up; when the external servo system drives the load platform to swing, the rotary transformer shaft rotates, inducing sine wave and cosine wave signals; and sends the sine wave and cosine wave signals to the rotary transformer signal filtering circuit.

[0049] Resolver signal filtering circuit: Receives sine wave and cosine wave signals from an external resolver, filters the sine wave and cosine wave signals, and then forwards them to the AD2S1210 decoding and buffering circuit.

[0050] like Figure 2 As shown, the AD2S1210 decoding and buffer circuit includes a U1 resolver-to-digital converter, a U2 passive crystal oscillator, C1 load capacitor, C2 load capacitor, C30 filter capacitor, C29 filter capacitor, C31 filter capacitor, RN1 damping array, RN2 damping array, RN3 damping array, U3 operational amplifier, D1 crossover bias diode, D2 crossover bias diode, resistors R1, R2, R3, R4, R5, R6, and R7. Resistors R8, R9, R10, R11, R12, R13, R14, R15, and R16; filter capacitor C3; filter capacitor C4; transistors Q1, Q2, Q3, and Q4; and a working mode selection circuit. The working mode selection circuit includes resistors R28, R29, R30, R31, and R32; a slide switch U9; and a slide switch U10.

[0051] Specifically, the RSE1 pin of chip U1 is connected to point 2 of the U9 slide switch; the RSE0 pin is connected to point 2 of the U10 slide switch; the NCS pin is the chip select signal, connected to resistor R29 and then to GND; in serial input mode, NCS remains low, and the NRD pin is connected to resistor R31 (pull-up resistor) and then to the external logic power signal VDRIVER; in serial input mode, the NRD pin remains high; the NFSYNC pin is connected to the RN1 damping bus and then to the STM32F407 main control circuit to implement edge logic input; the DGND pin is connected to signal ground; the DVDD pin is connected to the external 5V digital power supply; the CLKIN pin is connected to the output of the U2 passive crystal oscillator and also to one end of the C1 load capacitor; the other end of C1 is connected to signal ground; the XTALOUT pin is connected to the output of the U2 passive crystal oscillator and... The NSOE pin is connected to one end of the load capacitor C2; the other end of C2 is connected to signal ground; the NSOE pin is connected to one end of resistor R32; the other end of resistor R32 is connected to signal ground; NOSE is in serial input mode when set to low level; the SAMPLE pin is connected to the RN3 damping bus and then to the STM32F407 master control circuit to realize external sampling result judgment; the SDO pin is connected to the RN3 damping bus and then to the STM32F407 master control circuit for SPI2 bus slave device data output; the SDI pin is connected to the RN3 damping bus and then to the STM32F407 master control circuit for SPI2 bus slave device data input; the SCLK pin is connected to the RN3 damping bus and then to the STM32F407 master control circuit for the SPI2 bus clock signal; the VDRIVER pin is the external logic power supply connected to external 3.3V power supply; DGND pin connected to signal ground; Pin A connected to RN2 damping bus for external monitoring of incremental encoder simulation output A; Pin A connected to RN2 damping bus for external monitoring of incremental encoder simulation output B; NIM pin connected to RN2 damping bus for external monitoring of North Marker incremental encoder simulation output; DIR pin connected to RN2 damping bus for external monitoring of the direction of the resolver; RESET# pin connected to RN1 damping bus for connection to the STM32F407 main control circuit for reset enable signal; LOT pin connected to external LED indicator for tracking loss fault indication; DOS pin connected to external LED indicator for signal degradation fault indication; A1 pin connected to RN1 damping bus for connection to the STM32F407 main control circuit for mode selection 1; A0 pin connected to RN1 damping bus for connection to the STM32F407 main control circuit for mode selection 0; EXC pin connected to R14. One end of the resistor is used for the high-side input of the excitation signal; the EXC# pin is connected to one end of resistor R15 for the low-side input of the excitation signal; the AGND pin is connected to signal ground; the SIN pin is connected to the resolver signal filter circuit; the SINLO pin is connected to the resolver signal filter circuit; the AVDD pin is connected to an external analog 5V power supply; the COSLO pin is connected to the resolver signal filter circuit; the COS pin is connected to the resolver signal filter circuit; the REFBYP pin is connected to one end of both filter capacitors C30 and C31, and the other ends of filter capacitors C30 and C31 are connected to signal ground; the REFOUT pin is connected to one end of filter capacitor C29, and the other end of filter capacitor C29 is connected to signal ground.

[0052] EXC, the excitation signal high-side, is connected to one end of input resistor R14; the other end of input resistor R14 is connected to feedback resistor R13, and the other end of feedback resistor R13 is connected to the inverting input of channel A of op-amp U3. Simultaneously, resistor R13 is connected in parallel with filter capacitor C3 and marked with the EXC+ signal. The EXC+ signal is connected between resistors R9 and R10; resistor R9 is connected to the emitter of transistor Q1, and the base of transistor Q1 is connected between resistors R1 and R5; resistor R5 is pulled up to external power supply VCC+12; resistor R1 is connected to bidirectional diode D1 and then connected to the output of channel A of op-amp U3; resistor R10 is connected to the collector of transistor Q3, and the base of transistor Q3 is connected between resistors R2 and R6. Resistor R2 is connected to bidirectional diode D1 and then connected to the output of channel A of op-amp U3. The emitter of transistor Q3 is connected to analog ground AGND, and resistor R6 is also connected to analog ground AGND; EXC+, as the excitation amplification signal high-side, is connected to the primary winding R1 of the rotary transformer excitation terminal.

[0053] NEXC is the low end of the excitation signal. It is connected to the EXC- signal in the same way as the EXC signal through transistors Q2 and Q4, resistors R3, R4, R7, R8, R11, R12, R15, R16, capacitor C4, and bidirectional diode D2. EXC- is connected to the resolver as the low end of the excitation amplification signal.

[0054] The external logic power signal VDRIVER is connected to resistor R28 and outputs the H_V signal, which is then connected to point 1 of slide switches U9 and U10. The L_V signal is connected to point 3 of slide switches U9 and U10 after passing through resistor R30. Different resolution code values ​​are set for pins RES1 and RES0 of chip U1 by selecting different gears. The NCS signal is grounded through resistor R29 to enable the NCS signal at a low level. The NSOE signal is grounded through resistor R32 to enable the NSOE signal at a low level in serial input mode. The external logic power signal VDRIVER is connected to resistor R31 to set the NRD signal to a high level in serial input mode.

[0055] like Figure 3 As shown, the external rotary transformer has two primary windings and four secondary windings, namely primary winding M1, primary winding M2, secondary winding S1, secondary winding S2, secondary winding S3, and secondary winding S4. After the AD2S1210 decoding and buffer circuit outputs a sinusoidal excitation signal, the sinusoidal excitation signal generated between the EXC pin and the other pin is connected to the primary windings R1 and R2 of the rotary transformer through the buffer circuit. When the external servo system drives the load platform to swing, the rotary transformer shaft rotates. The two staggered secondary windings S1 and S3 on the shaft stator induce sinusoidal signals, which are connected to the SIN and SINLO pins through the filter circuit. The secondary windings S2 and S4 induce cosine signals, which are connected to the COS and COSLO pins through the filter circuit. The signals then enter the AD2S1210 decoding and buffer circuit again, and after internal conversion, obtain the digital signals corresponding to the shaft angle and speed.

[0056] like Figure 4The resolver signal filtering circuit includes U8 terminal block, L4 common mode inductor, L5 common mode inductor, L6 differential mode inductor, L7 differential mode inductor, L8 differential mode inductor, L9 differential mode inductor, C32 capacitor, C33 capacitor, C34 capacitor, C35 capacitor, C36 capacitor, C37 capacitor, R113 resistor, and R114 resistor. The SIN+ pin of terminal U8 is the high end of the sinusoidal signal output from the resolver, connected to the input of the first winding of the L4 common-mode inductor. The output of the first winding of L4 is connected to the input of the L6 differential-mode inductor. The output of the L6 differential-mode inductor is connected to one end of the C32 differential-mode capacitor, one end of the R113 damping resistor, and one end of the C33 common-mode capacitor, outputting the SIN1+ signal to the SIN1+ pin of the U1 chip. The SIN- pin of terminal U8 is the low end of the sinusoidal signal output from the resolver, connected to the input of the second winding of the L4 common-mode inductor. The output of the second winding of L4 is connected to the input of the L7 differential-mode inductor. The output of the L7 differential-mode inductor is connected to the other end of the C32 differential-mode capacitor, the other end of the R113 damping resistor, and one end of the C34 common-mode capacitor, outputting the SIN1- signal to the SIN1- pin of the U1 chip. The other ends of the C33 and C34 common-mode capacitors are connected to the signal... Ground; The COS+ pin of terminal U8 is the high end of the cosine signal output from the rotary transformer, connected to the input terminal of the first winding of the L5 common-mode inductor. The output terminal of the first winding of L5 is connected to the input terminal of the L8 differential-mode inductor. The output terminal of the L8 differential-mode inductor is connected to one end of the C35 differential-mode capacitor, one end of the R114 damping resistor, and one end of the C36 common-mode capacitor, then outputting the COS1+ signal to the COS1+ pin of the U1 chip; The COS- pin of terminal U8 is the low end of the cosine signal output from the rotary transformer, connected to the input terminal of the second winding of the L5 common-mode inductor. The output terminal of the second winding of L5 is connected to the input terminal of the L9 differential-mode inductor. The output terminal of the L9 differential-mode inductor is connected to the other end of the C35 differential-mode capacitor, one end of the R114 damping resistor, and one end of the C37 common-mode capacitor, then outputting the COS1- signal to the COS1- pin of the U1 chip; The other ends of the C36 and C37 common-mode capacitors are connected to signal ground.

[0057] like Figure 5 The STM32F407 main control circuit includes the U11 main control chip STM32F407 microcontroller, the U10 Ethernet interface chip W5500, the RN6 damping resistor array, and the RJ1 Ethernet transformer.

[0058] Specifically, pin PB13 of the U11 chip is connected to pin SCLKS of the RN3 damping resistor array for the SPI2 bus clock signal; pin PB14 is connected to pin SDOS of the RN3 damping resistor array for SPI2 bus slave data output; pin PB15 is connected to pin SDIS of the RN3 damping resistor array for SPI2 bus slave data input; pin PD8 is connected to pin SAMS of the RN3 damping resistor array for external sampling result judgment; pin PA11 of the U11 chip is connected to one end of resistor R111; the other end of resistor R111 is connected to pin 1 of USB1; pin PA12 of the U11 chip is connected to one end of resistor R112; the other end of resistor R112 is connected to pin 2 of USB1; pin PB3 of the U11 chip is connected to pin SCLK of the U10 chip for the SPI1 bus clock. Signals; PB4 pin is connected to the U10 chip's MISO pin for SPI1 bus master input / slave output; PB5 pin is connected to the U10 chip's MOSI pin for SPI1 bus master output / slave input; PB8 pin is connected to the U10 chip's RSTN pin for SPI1 bus reset signal; PB9 pin is connected to the U10 chip's INTN pin for SPI1 bus interrupt signal; PA15 pin is connected to the U10 chip's SCAN pin for SPI1 bus chip select signal; U10 chip's TXN, TXP, RXN, and RXP pins are connected to the input terminals of the RN6 damping resistor array; the output terminals of the RN6 damping resistor array are respectively connected to the TD-, TD+, RD+, and RD- pins of the RJ1 Ethernet transformer for Ethernet transmit signal low end, transmit signal high end, receive signal high end, and receive signal low end.

[0059] The external host PC sends resolver signal test commands to the STM32F407 main control circuit via an Ethernet TCP / IP protocol interface or a USB 2.0 interface. After parsing the resolver signal test commands into resolver measurement start commands, the STM32F407 main control circuit sends the resolver measurement start commands to the AD2S1210 decoding and buffering circuit via the SPI2 serial peripheral device interface.

[0060] The AD2S1210 decoding and buffering circuit sends the digital values ​​corresponding to the shaft angle and speed to the STM32F407 main control circuit through the SPI2 serial peripheral device interface; the STM32F407 main control circuit sends the digital values ​​corresponding to the shaft angle and speed to the external host PC through the Ethernet TCP / IP protocol interface or USB 2.0 interface.

[0061] like Figure 6 The SPI2 serial peripheral device interface is as follows:

[0062] The NSOE pin is kept low to select this serial interface. The serial interface of the AD2S1210 decoding and buffering circuit consists of four signals: SDO, SDI, WR / FSYNC, and SCLK. SDI is used to transfer data to the on-chip registers, and SDO is used to retrieve data from the on-chip registers, including position, speed, and fault registers. SCLK is the device's serial clock input, and all data transfers are performed relative to this SCLK signal. WR / FSYNC is used for frame synchronization data. The falling edge of WR / FSYNC takes the SDI and SDO lines out of the high-impedance state, and the rising edge of WR / FSYNC returns the SDI and SDO lines to the high-impedance state. The serial interface does not require a CS input; CS is kept low.

[0063] The SDO output process is as follows:

[0064] In normal operating mode, data is shifted out of the device as a 24-bit word under the control of the serial clock input SCLK; data is shifted out on the rising edge of SCLK.

[0065] The SDI input process is as follows:

[0066] In configuration mode, it addresses on-chip registers and is used as daisy-chain inputs; data is shifted into the device on the falling edge of SCLK.

[0067] This invention designs a resolver demodulation circuit module, using the AD2S1210 as the core decoding chip, achieving a resolution of up to 16 bits. It incorporates a two-stage buffer circuit: a high-precision operational amplifier for the first-stage signal amplification and a push-pull amplifier for the second-stage power amplification. A cascaded resolver signal filtering circuit employing a common-mode inductor preamplifier and a differential T-type LC filter effectively suppresses both common-mode interference and out-of-band differential-mode interference, improving the system's anti-interference performance. An STM32F407 microcontroller is used to expand the USB interface, and a W5500 interface circuit is used to expand the Ethernet interface for communication with the host computer.

[0068] The AD2S1210 decoding and buffer circuitry is part of a 10-bit to 16-bit resolution resolver-to-digital converter that integrates an on-chip programmable sine wave oscillator to provide sine wave excitation for the resolver. The converter's sine and cosine inputs allow input signals ranging from 2kHz to 20kHz at 3.15V pp±27%. A Type II servo loop tracks the input signal and converts the information from the sine and cosine inputs into digital values ​​corresponding to the input angle and speed. The maximum tracking rate is 3125 rpm.

[0069] According to the AD2S1210 chip datasheet, the EXC and NEXC excitation signals are connected to the excitation terminals R1 and R2 of the resolver after passing through a buffer circuit. The two outputs of the resolver are filtered by a filter circuit and then enter the SIN, SINLO, COS, and COSLO pins of the chip.

[0070] The two complementary outputs of the EXC and NEXC signals cannot be directly used to excite the resolver; they need to pass through a buffer circuit. The design of the buffer circuit depends on the resolver used. The buffer circuit provided in this invention is as follows: Figure 1 As shown, EXC and NEXC undergo a first-stage signal amplification via op-amp U3. Considering the peak input voltage of AD2S1210 is 3.15V pp±27%, and the output range of EXC and NEXC is 3.2-4.0V, a reference voltage VREF is added according to the chip datasheet. Through a 12V power supply and R21, R22, the voltage is divided to 3.75V, resulting in a distortion-free output waveform. The signal after the first-stage amplification undergoes a second-stage power amplification using a push-pull amplifier circuit composed of Q1, Q2 (SS8050 NPN transistors) and Q3, Q4 (SS8550 PNP transistors). Capacitors C3 and C4 are used for filtering the EXC and NEXC signals.

[0071] The gain and output voltage of the buffer circuit are given by formulas (1) and (2):

[0072]

[0073] Where: ω is the signal angular frequency, VREF = 3.75V, R13 = 10KΩ, R14 = 12KΩ, C3 = 100pF.

[0074] From (1), we get:

[0075]

[0076] This invention relates to a resolver signal filtering circuit. Designed to meet the filter requirements of resolver sine / cosine signals (frequency range 2kHz-20kHz), it combines a common-mode inductor and a differential T-type filter to suppress common-mode interference (such as ground noise) and out-of-band differential-mode noise (such as switching power supply harmonics), while retaining the useful signal in the 2-20kHz range. A cascaded structure of a common-mode inductor pre-amplifier and a differential T-type LC filter ensures synergistic effects of common-mode suppression and differential-mode filtering. Figure 6 In the filter structure, the first stage is a common-mode inductor (to suppress common-mode noise), and the second stage is a differential-mode low-pass filter (composed of two inductors and one differential-mode capacitor to suppress high-frequency differential-mode noise). Since the SIN+ and SIN- paths, and COS+ and COS- paths are identical, we will use SIN+ and SIN- as an example:

[0077] 1. The differential mode path consists of L6, L7 and C32;

[0078] Total differential inductance:

[0079] L dm =L6+L7 (3)

[0080] The equivalent differential-mode capacitance is formed by combining a differential-mode capacitor and a common-mode capacitor in series and then in parallel:

[0081] Equivalent differential-mode capacitance:

[0082]

[0083] Therefore, the differential cutoff frequency is:

[0084]

[0085] Assuming the target cutoff frequency is greater than 30kHz, when taking...

[0086] L6=L7=4.7mH, C32=2.7nF, C33=C34=390pF

[0087] Therefore, from formulas (3) and (4), we get Ldm = 9.4mH and Cdm = 2.895nF.

[0088] From formula (5), we get:

[0089]

[0090] 2. The common-mode path consists of L4, C33, and C34;

[0091] The target cutoff frequency is >50kHz, so L4 = 10mH is chosen.

[0092] The total mode inductance is composed of the parallel values ​​of common mode inductance L4 and differential mode inductances L6 and L7 connected in series:

[0093] The total modulus inductance is:

[0094] The common-mode capacitance is: Ccm = 390pF + 390 = 780pF.

[0095] Common mode cutoff frequency:

[0096]

[0097] therefore,

[0098] 3. Adding a parallel resistor R113 to the differential-mode resonant circuit can provide a damping effect, as calculated below:

[0099] a. Characteristic impedance calculation:

[0100]

[0101] b. Critical damping resistance

[0102] Butterworth response target damping factor ζ = 0.707;

[0103] Critical damping resistance:

[0104] The nominal value is taken as: R113 = 1.3KΩ (close to the theoretical value);

[0105] c. Damping factor verification

[0106]

[0107] Verification conclusion: The system has the flattest passband and good phase linearity.

[0108] In this invention, the STM32F407 main control circuit incorporates the core chip U11, model number:

[0109] The STM32F407ZGT6 chip has a main frequency of 168MHz, 192KB SRAM, 1024KB FLASH, and is packaged in an LQFP144 package. Utilizing its rich peripheral resources, it expands the SPI interface with the AD2S1210 decoder circuit, and also expands the Ethernet and USB interfaces for the host computer.

[0110] This invention proposes a rotary transformer to replace the sliding rheostat sensor, which solves the problems of low accuracy, slow dynamic response, and frequent zeroing required in the angular displacement test of the load stage of electromechanical servo mechanisms, and significantly improves the testing efficiency and environmental adaptability of servo mechanisms.

[0111] This invention achieves a maximum resolution of 16 bits based on the AD2S1210 chip, with a data jump bit of ≤2LSB and a tracking rate of 3125rps at 10-bit resolution, meeting the requirements for high-precision angular position measurement.

[0112] This invention employs a cascaded design of a common-mode inductor and a differential T-type LC filter to effectively suppress common-mode noise (such as ground interference) and high-frequency differential-mode noise (such as switching power supply harmonics), while retaining an effective signal of 2-20kHz.

[0113] The two-stage push-pull buffer circuit (high-precision operational amplifier + power amplifier) ​​of this invention replaces the traditional single-stage amplification, reduces signal distortion, and ensures that the excitation signal (3.2-4.0V pp) is stably transmitted to the resolver sensor.

[0114] This invention integrates Ethernet (10 / 100M) and USB 2.0 interfaces, supporting flexible communication with host computers and adapting to diverse industrial control scenarios.

[0115] This invention adopts a modular design to support the upgrade of servo load tables and the standardization of new equipment. It is applicable to multiple fields such as digital production lines and aerospace, and has the advantages of miniaturization, high reliability and low cost.

[0116] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A rotary transformer demodulation circuit module, characterized in that: Includes AD2S1210 decoding and buffering circuit, resolver signal filtering circuit and STM32F407 main control circuit; The STM32F407 main control circuit receives resolver signal test commands from an external host PC; after parsing the resolver signal test commands, it generates a resolver measurement start command; and sends the resolver measurement start command to the AD2S1210 decoding and buffering circuit; it receives the digital values ​​corresponding to the shaft angle and speed from the AD2S1210 decoding and buffering circuit, and sends the digital values ​​corresponding to the shaft angle and speed to the external host PC, completing the acquisition and demodulation of the resolver signal. The AD2S1210 decoding and buffering circuit receives the resolver measurement start command from the STM32F407 main control circuit, generates a sinusoidal excitation signal, and sends the sinusoidal excitation signal to the external resolver; it also receives the filtered sinusoidal and cosine signals from the resolver signal filtering circuit, converts them into digital quantities corresponding to the shaft angle and speed, and sends the digital quantities corresponding to the shaft angle and speed to the STM32F407 main control circuit. External rotary transformer: Receives the sinusoidal excitation signal from the AD2S1210 decoding and buffering circuit to start up; when the external servo system drives the load platform to swing, the rotary transformer shaft rotates, inducing sine and cosine signals; and sends the sine and cosine signals to the rotary transformer signal filtering circuit; Resolver signal filtering circuit: Receives sine wave and cosine wave signals from an external resolver, filters the sine wave and cosine wave signals, and then forwards them to the AD2S1210 decoding and buffering circuit.

2. The rotary transformer demodulation circuit module according to claim 1, characterized in that: The AD2S1210 decoding and buffer circuit includes a U1 resolver-to-digital converter, a U2 passive crystal oscillator, C1 load capacitor, C2 load capacitor, C30 filter capacitor, C29 filter capacitor, C31 filter capacitor, RN1 damping array, RN2 damping array, RN3 damping array, U3 operational amplifier, D1 crossover bias diode, D2 crossover bias diode, resistors R1, R2, R3, R4, R5, R6, R7, and an electrical... Resistors R8, R9, R10, R11, R12, R13, R14, R15, and R16; filter capacitor C3; filter capacitor C4; transistors Q1, Q2, Q3, and Q4; and a working mode selection circuit; wherein the working mode selection circuit includes resistors R28, R29, R30, R31, and R32, and slide switches U9 and U10. Specifically, the RSE1 pin of chip U1 is connected to point 2 of the U9 slide switch; the RSE0 pin is connected to point 2 of the U10 slide switch; the NCS pin is the chip select signal, connected to resistor R29 and then to GND; in serial input mode, NCS remains low, and the NRD pin is connected to resistor R31 (pull-up resistor) and then to the external logic power signal VDRIVER; in serial input mode, the NRD pin remains high; the NFSYNC pin is connected to the RN1 damping bus and then to the STM32F407 main control circuit to implement edge logic input; the DGND pin is connected to signal ground; the DVDD pin is connected to the external 5V digital power supply; the CLKIN pin is connected to the output of the U2 passive crystal oscillator and also to one end of the C1 load capacitor; the other end of C1 is connected to signal ground; the XTALOUT pin is connected to the output of the U2 passive crystal oscillator and... The NSOE pin is connected to one end of the load capacitor C2; the other end of C2 is connected to signal ground; the NSOE pin is connected to one end of resistor R32; the other end of resistor R32 is connected to signal ground; NOSE is in serial input mode when set to low level; the SAMPLE pin is connected to the RN3 damping bus and then to the STM32F407 master control circuit to realize external sampling result judgment; the SDO pin is connected to the RN3 damping bus and then to the STM32F407 master control circuit for SPI2 bus slave device data output; the SDI pin is connected to the RN3 damping bus and then to the STM32F407 master control circuit for SPI2 bus slave device data input; the SCLK pin is connected to the RN3 damping bus and then to the STM32F407 master control circuit for the SPI2 bus clock signal; the VDRIVER pin is the external logic power supply connected to external 3.3V power supply; DGND pin connected to signal ground; Pin A connected to RN2 damping bus for external monitoring of incremental encoder simulation output A; Pin A connected to RN2 damping bus for external monitoring of incremental encoder simulation output B; NIM pin connected to RN2 damping bus for external monitoring of NorthMarker incremental encoder simulation output; DIR pin connected to RN2 damping bus for external monitoring of the resolver direction; RESET# pin connected to RN1 damping bus, connected to the STM32F407 main control circuit, used for reset enable signal; LOT pin connected to external LED indicator for tracking loss fault indication; DOS pin connected to external LED indicator for signal degradation fault indication; Pin A1 connected to RN1 damping bus, connected to the STM32F407 main control circuit, used for mode... Select option 1; pin A0 is connected to the RN1 damping bus, then to the STM32F407 main control circuit for mode selection 0; pin EXC is connected to one end of resistor R14 for high-side excitation signal input, pin EXC# is connected to one end of resistor R15 for low-side excitation signal input; pin AGND is connected to signal ground; pin SIN is connected to the resolver signal filter circuit; pin SINLO is connected to the resolver signal filter circuit; pin AVDD is connected to an external analog 5V power supply; pin COSLO is connected to the resolver signal filter circuit; pin COS is connected to the resolver signal filter circuit; pin REFBYP is connected to one end of both filter capacitors C30 and C31, the other ends of which are connected to signal ground; pin REFOUT is connected to one end of filter capacitor C29, the other end of which is connected to signal ground. EXC, the excitation signal, is connected to one end of the input resistor R14. The other end of the input resistor R14 is connected to the feedback resistor R13, and the other end of the feedback resistor R13 is connected to the inverting input of channel A of op-amp U3. Simultaneously, resistor R13 is connected in parallel with filter capacitor C3 and marked with the EXC+ signal. The EXC+ signal is connected between resistors R9 and R10. Resistor R9 is connected to the emitter of transistor Q1, and the base of transistor Q1 is connected between resistors R1 and R5. Resistor R5 is pulled up to the external power supply VCC+12. Resistor R1 is connected to bidirectional diode D1 and then connected to the output of channel A of op-amp U3. Resistor R10 is connected to the collector of transistor Q3, and the base of transistor Q3 is connected between resistors R2 and R6. Resistor R2 is connected to bidirectional diode D1 and then connected to the output of channel A of op-amp U3. The emitter of transistor Q3 is connected to analog ground AGND, and resistor R6 is also connected to analog ground AGND. EXC+, as the excitation amplification signal, is connected to the primary winding R1 of the rotary transformer's excitation terminal. NEXC is the low end of the excitation signal. It is connected to the EXC- signal in the same way as the EXC signal through transistors Q2 and Q4, resistors R3, R4, R7, R8, R11, R12, R15, R16, capacitor C4, and bidirectional diode D2. EXC- is connected to the resolver as the low end of the excitation amplification signal. The external logic power signal VDRIVER is connected to resistor R28 and outputs the H_V signal, which is then connected to point 1 of slide switches U9 and U10. The L_V signal is connected to point 3 of slide switches U9 and U10 after passing through resistor R30. Different resolution code values ​​are set for pins RES1 and RES0 of chip U1 by selecting different gears. The NCS signal is grounded through resistor R29 to enable the NCS signal at a low level. The NSOE signal is grounded through resistor R32 to enable the NSOE signal at a low level in serial input mode. The external logic power signal VDRIVER is connected to resistor R31 to set the NRD signal to a high level in serial input mode.

3. The rotary transformer demodulation circuit module according to claim 2, characterized in that: The external rotary transformer is equipped with two primary windings at the excitation end and four secondary windings, namely primary winding M1, primary winding M2, secondary winding S1, secondary winding S2, secondary winding S3, and secondary winding S4. After the AD2S1210 decoding and buffer circuit outputs a sinusoidal excitation signal, the sinusoidal excitation signal generated between the EXC pin and the other pin is connected to the primary windings R1 and R2 of the rotary transformer through the buffer circuit. When the external servo system drives the load platform to swing, the rotary transformer shaft rotates. The two staggered secondary windings S1 and S3 on the shaft stator induce sinusoidal signals, which are connected to the SIN and SINLO pins through the filter circuit. The secondary windings S2 and S4 induce cosine signals, which are connected to the COS and COSLO pins through the filter circuit. The signals then enter the AD2S1210 decoding and buffer circuit again, and after internal conversion, obtain the digital signals corresponding to the shaft angle and speed.

4. The rotary transformer demodulation circuit module according to claim 3, characterized in that: The resolver signal filtering circuit includes U8 terminal block, L4 common mode inductor, L5 common mode inductor, L6 differential mode inductor, L7 differential mode inductor, L8 differential mode inductor, L9 differential mode inductor, C32 capacitor, C33 capacitor, C34 capacitor, C35 capacitor, C36 capacitor, C37 capacitor, R113 resistor, and R114 resistor. The SIN+ pin of terminal U8 is the high end of the sinusoidal signal output from the resolver, connected to the input of the first winding of the L4 common-mode inductor. The output of the first winding of L4 is connected to the input of the L6 differential-mode inductor. The output of the L6 differential-mode inductor is connected to one end of the C32 differential-mode capacitor, one end of the R113 damping resistor, and one end of the C33 common-mode capacitor, outputting the SIN1+ signal to the SIN1+ pin of the U1 chip. The SIN- pin of terminal U8 is the low end of the sinusoidal signal output from the resolver, connected to the input of the second winding of the L4 common-mode inductor. The output of the second winding of L4 is connected to the input of the L7 differential-mode inductor. The output of the L7 differential-mode inductor is connected to the other end of the C32 differential-mode capacitor, the other end of the R113 damping resistor, and one end of the C34 common-mode capacitor, outputting the SIN1- signal to the SIN1- pin of the U1 chip. The other ends of the C33 and C34 common-mode capacitors are connected to the signal... Ground; The COS+ pin of terminal U8 is the high end of the cosine signal output from the rotary transformer, connected to the input terminal of the first winding of the L5 common-mode inductor. The output terminal of the first winding of L5 is connected to the input terminal of the L8 differential-mode inductor. The output terminal of the L8 differential-mode inductor is connected to one end of the C35 differential-mode capacitor, one end of the R114 damping resistor, and one end of the C36 common-mode capacitor, then outputting the COS1+ signal to the COS1+ pin of the U1 chip; The COS- pin of terminal U8 is the low end of the cosine signal output from the rotary transformer, connected to the input terminal of the second winding of the L5 common-mode inductor. The output terminal of the second winding of L5 is connected to the input terminal of the L9 differential-mode inductor. The output terminal of the L9 differential-mode inductor is connected to the other end of the C35 differential-mode capacitor, one end of the R114 damping resistor, and one end of the C37 common-mode capacitor, then outputting the COS1- signal to the COS1- pin of the U1 chip; The other ends of the C36 and C37 common-mode capacitors are connected to signal ground.

5. A rotary transformer demodulation circuit module according to claim 4, characterized in that: The STM32F407 main control circuit includes the U11 main control chip STM32F407 microcontroller, the U10 Ethernet interface chip W5500, the RN6 damping resistor array, and the RJ1 Ethernet transformer. Specifically, pin PB13 of the U11 chip is connected to pin SCLKS of the RN3 damping resistor array for the SPI2 bus clock signal; pin PB14 is connected to pin SDOS of the RN3 damping resistor array for SPI2 bus slave data output; pin PB15 is connected to pin SDIS of the RN3 damping resistor array for SPI2 bus slave data input; pin PD8 is connected to pin SAMS of the RN3 damping resistor array for external sampling result judgment; pin PA11 of the U11 chip is connected to one end of resistor R111; the other end of resistor R111 is connected to pin 1 of USB1; pin PA12 of the U11 chip is connected to one end of resistor R112; the other end of resistor R112 is connected to pin 2 of USB1; pin PB3 of the U11 chip is connected to pin SCLK of the U10 chip for the SPI1 bus clock. Signals; PB4 pin is connected to the U10 chip's MISO pin for SPI1 bus master input / slave output; PB5 pin is connected to the U10 chip's MOSI pin for SPI1 bus master output / slave input; PB8 pin is connected to the U10 chip's RSTN pin for SPI1 bus reset signal; PB9 pin is connected to the U10 chip's INTN pin for SPI1 bus interrupt signal; PA15 pin is connected to the U10 chip's SCAN pin for SPI1 bus chip select signal; U10 chip's TXN, TXP, RXN, and RXP pins are connected to the input terminals of the RN6 damping resistor array; the output terminals of the RN6 damping resistor array are respectively connected to the TD-, TD+, RD+, and RD- pins of the RJ1 Ethernet transformer for Ethernet transmit signal low end, transmit signal high end, receive signal high end, and receive signal low end.

6. The rotary transformer demodulation circuit module according to claim 1, characterized in that: The external host PC sends resolver signal test commands to the STM32F407 main control circuit via an Ethernet TCP / IP protocol interface or a USB 2.0 interface. After parsing the resolver signal test commands into resolver measurement start commands, the STM32F407 main control circuit sends the resolver measurement start commands to the AD2S1210 decoding and buffering circuit via the SPI2 serial peripheral device interface.

7. The rotary transformer demodulation circuit module according to claim 1, characterized in that: The AD2S1210 decoding and buffering circuit sends the digital values ​​corresponding to the shaft angle and speed to the STM32F407 main control circuit through the SPI2 serial peripheral device interface; the STM32F407 main control circuit sends the digital values ​​corresponding to the shaft angle and speed to the external host PC through the Ethernet TCP / IP protocol interface or USB2.0 interface.

8. A rotary transformer demodulation circuit module according to claim 6 or 7, characterized in that: The SPI2 serial peripheral device interface is: The NSOE pin is kept low to select this serial interface. The serial interface of the AD2S1210 decoding and buffering circuit consists of four signals: SDO, SDI, WR / FSYNC, and SCLK. SDI is used to transfer data to the on-chip registers, and SDO is used to retrieve data from the on-chip registers, including position, speed, and fault registers. SCLK is the device's serial clock input, and all data transfers are performed relative to this SCLK signal. WR / FSYNC is used for frame synchronization data. The falling edge of WR / FSYNC takes the SDI and SDO lines out of the high-impedance state, and the rising edge of WR / FSYNC returns the SDI and SDO lines to the high-impedance state. The serial interface does not require a CS input; CS is kept low.

9. A rotary transformer demodulation circuit module according to claim 8, characterized in that: The SDO output process is as follows: In normal operating mode, data is shifted out of the device as a 24-bit word under the control of the serial clock input SCLK; data is shifted out on the rising edge of SCLK.

10. A rotary transformer demodulation circuit module according to claim 8, characterized in that: The SDI input process is as follows: In configuration mode, it addresses on-chip registers and is used as daisy-chain inputs; data is shifted into the device on the falling edge of SCLK.

Images