CN101968367A - Multifunctional networking digital shaft angle converter and converting method thereof - Google Patents

Abstract

The invention provides a multifunctional networked digital shaft-angle converter and a conversion method. The PC is connected to the TMS320F2808 digital controller through the serial port level conversion circuit, and the initial hardware and software settings are completed through the host computer software; Transfer information, and complete the axis angle conversion operation in the TMS320F2808 digital controller. The result obtained by the operation is transmitted to the control circuit board by the parallel data output circuit, or transmitted to the industrial bus as an industrial control network node through the 485 and CAN bus interface. The invention can simplify the structure of the device and reduce the cost; it has general functions and can realize a variety of shaft angle sensor interfaces, and can realize the interface and conversion of the induction synchronizer, the rotary transformer and the photoelectric code disc through the function selection software; The interface of the bus has the characteristics of multi-functional networking.

Description

Multifunctional networked digital shaft-angle converter and its conversion method

technical field

The invention relates to a sensor processing and detection technology, in particular to a digital conversion technology of a rotary encoder and a sine-cosine encoder realized based on a digital processor.

Background technique

In industrial control and detection, angular position is a very important parameter. Inductive synchronizers, resolvers, synchros, and photoelectric code discs are often used as angle sensing elements, combined with shaft-angle converters to form an angle measurement system.

The core of the shaft-angle converter is how to process the angle sensor signal and convert the sensor information into a digital value that is easy for computers and other systems to process. In the angle measurement system, in the past, the design of the shaft-angle converter was mostly realized by combining the analog circuit and the digital circuit. For example, special-purpose chips combined with external analog circuits, such as AD2S8X of AD Company and RDC-19220 series of DDC Company, convert two quadrature induction signals into digital angle values. The advantage of using the combination of analog circuit and digital circuit is that it can meet the high-resolution requirements. The disadvantage is that there are many peripheral components, complex use and expensive price. If the analog device configuration is wrong, the angle measurement circuit cannot work normally, which greatly limits it. scope of application.

At present, the intelligentization of industrial sites requires the integration of network functions into sensors, so that sensors can be used as a relatively independent and intelligent unit to transmit detection information through the network and receive control information from the host computer, becoming a networked intelligent sensor. Due to the complexity of the test object and the real-time requirements of the application, the system requires the shaft-angle converter to have strong information processing and transmission capabilities.

In order to meet the networked and intelligent requirements of the shaft angle changer and solve the application limitations of the combination of analog circuits and digital circuits, the high-performance processor TMS320F2808 is used to realize the all-digital with simple circuit and multiple network interface capabilities that can be easily selected. Shaft angle conversion device.

Find through searching existing technical documents, there is a bibliographical report identical or similar with the subject of the present invention in the CNKI database, called " the design research of permanent magnet brushless DC motor direct torque control system " (Master's thesis of Hunan University, Published on March 2, 2009), this article uses a dedicated chip combined with an external analog circuit, which is different from the multi-functional networked digital axis-angle converter.

Contents of the invention

The purpose of the present invention is to provide a multifunctional networked digital axis-angle converter capable of simplifying the structure of the device and reducing costs; capable of realizing interfaces based on common industrial field buses and having multifunctional networking. The object of the present invention is also to provide a multifunctional networked digital axis-angle transformation method.

The purpose of the present invention is achieved like this:

The multifunctional networked digital axis-angle conversion device mainly includes sensor interface buffer circuit 2, TMS320F2808 digital controller 3 and serial-parallel data interface; the serial-parallel data interface further includes parallel data output circuit 4, serial port level conversion circuit 5 and 485 and CAN bus interface 6; the PC 8 is connected to the TMS320F2808 digital controller 3 through the serial port level conversion circuit 5, and the initial hardware and software settings are completed through the upper computer 8 software, including setting the axis angle conversion method and hardware connection setting ; After completing the initial setting and connecting the hardware, the angular position sensor 1 and the TMS320F2808 digital controller 3 transmit information through the sensor interface and the buffer circuit 2, and complete the shaft angle conversion operation in the TMS320F2808 digital controller 3, and the result of the operation is obtained by the parallel The data output circuit 4 is transmitted to the control circuit board 7, or transmitted to the industrial bus 9 through the 485 and CAN bus interface 6 as an industrial control network node, and can also be read by the upper PC 8 monitoring program through the serial port level conversion circuit 5.

The multifunctional networked digital axis angle conversion method is as follows: the upper PC 8 performs the hardware connection selection switch 23 to complete the hardware connection selection, and at the same time selects the axis angle conversion mode in the CPU central processing unit 16; the PWM generation module 15 carried by TMS320F2808 The generated high-frequency pulse signal is filtered and buffered by the circuit 22 to generate a high-frequency sine wave signal, and the high-frequency sine wave signal is input into the resolver 10 as an excitation signal to make the resolver 10 start to work, and the sine-cosine encoder or resolver 10 outputs two channels The quadrature voltage signal is introduced into the device by the differential receiver 11, processed by the comparator 12 to form a rough measurement pulse, which is integrated by the QEP module 13 of the TMS320F2808, and the result of the integration is given to the CPU module 16 of the TMS320F2808; the analog signal passes through the ADC of the white belt of the TMS320F2808 The module 14 performs sampling, holding and conversion processing to form a digital voltage signal to the CPU module 16, and the CPU module 16 performs an axis-angle transformation algorithm operation to obtain real-time angular position and angular velocity information, and transmits information to the outside through a multi-channel interface; The I/O module 17 of the belt completes the connection of the external control circuit board type circuit through the parallel data interface mode or through the built-in SPI module 18, and the CPU module 16 connects to the upper PC through the common asynchronous serial interface A19 that comes with it. The monitoring software of computer 8 outputs the conversion results; for the bus interface requirements, the upper PC 8 first sets the network address through software, and then the general asynchronous serial interface B20 of the white belt or the built-in CAN communication interface 21 passes through the 485 and CAN interface The level conversion circuit 6 completes the level interface conversion, and the obtained result is put into the industrial bus 9 and read by the master station.

The invention provides a set of all-digital shaft-angle conversion device and method, which replaces the analog and digital mixed scheme, can simplify the structure of the device, and reduce costs; the shaft-angle conversion device has general functions, and can realize various shaft-angle sensor interfaces. Selecting software can realize the interface and conversion of induction synchronizer, resolver and photoelectric code disc; with intelligent network processing function, it can realize the interface based on common industrial field bus, and has the characteristics of multi-functional network.

Main features of the present invention are reflected in:

1. The TMS320F2808 chip has the characteristics of better processing performance, higher peripheral integration, larger program memory, and faster A/D conversion speed in the digital control of the motor. It is an ideal upgrade product for digital information processing and has low cost. , low power consumption, high performance characteristics.

2. The same hardware connection specifications and models are convenient for connection, and there are multiple functional interfaces for selection, and the same type of connectors can be used for different encoders.

3. With intelligent network processing function, it can realize the interface based on common industrial field bus, and has the characteristics of multi-functional network.

4. The function can be selected through the PC without modification on the hardware, the reconfiguration of multiple functions can be completed, the analog multi-channel switch can be controlled through the I/O port, and then how to connect the external multiplexing circuit can be selected.

5. It can be used as an industrial network node, and the address can be set through a PC to form a network node based on MODBUS or CAN bus.

6. The software of the TMS320F2808 chip can be upgraded, the functions of the device can be increased, or the software functions can be revised according to the needs.

Description of drawings

Figure 1 is a composition diagram of a multifunctional networked digital axis-angle conversion device;

Figure 2 is a schematic diagram of the operation of a multifunctional networked digital axis-angle conversion device;

Fig. 3 is the minimum system circuit diagram of the TMS320F2808 of the multifunctional networked digital axis-angle conversion device;

Fig. 4 is the circuit diagram of the shaft-angle transformation part of the multifunctional networked digital shaft-angle transformation device;

Fig. 5 is a circuit diagram of the external communication interface of the multifunctional networked digital axis-angle conversion device.

Detailed ways

The present invention is described in more detail below in conjunction with accompanying drawing example:

In conjunction with Fig. 1, the composition of the present invention is a multifunctional networked digital shaft-angle conversion device comprising: 1-angular position sensor; 2-sensor interface buffer circuit; 3-TMS320F2808 digital controller; 4-parallel digital output circuit; 5-serial Line interface level conversion circuit; 6-485 and CAN interface level conversion circuit; 7-external control circuit board; 8-upper PC; 9-industrial bus.

Figure 2 shows the operating principle of the multifunctional networked digital axis-angle conversion device, in which: 10-sensors such as sine-cosine encoder or resolver; 11-differential receiver; 12-comparator; 13-QEP module that comes with TMS320F2808; 14-ADC module of TMS320F2808; 15-PWM generation module of TMS320F2808; 16-CPU module of TMS320F2808; 17-I/O module of TMS320F2808 white belt; 18-SPI interface of TMS320F2808; 20-TMS320F2808’s own universal asynchronous serial interface B; 21-TMS320F2808’s own CAN communication interface; 22-filtering and buffering circuit; 23-hardware connection selection switch.

Combined with Figure 1, the composition diagram of the multifunctional networked digital axis-angle conversion device is mainly composed of sensor interface buffer circuit 2, TMS320F2808 digital controller 3 and serial-parallel data interface. The serial-parallel data interface is composed of parallel data output circuit 4, serial port level conversion circuits 5 and 485 and CAN bus interface 6. The PC 8 is connected to the TMS320F2808 digital controller 3 through the serial port level conversion circuit 5, and the initial hardware and software settings are completed through the software of the host computer 8, including setting the shaft angle conversion method and hardware connection. After completing the initial setting and connecting the hardware, the angular position sensor 1 and the TMS320F2808 digital controller 3 transmit information through the sensor interface and the buffer circuit 2, and complete the shaft angle conversion operation in the TMS320F2808 digital controller 3, and the result of the operation can be obtained by parallel The data output circuit 4 is transmitted to the control circuit board 7, or transmitted to the industrial bus 9 through the 485 and CAN bus interface 6 as an industrial control network node, and can also be read by the upper PC 8 monitoring program through the serial port level conversion circuit 5.

With reference to FIG. 2 , the host PC 8 performs the hardware connection selection switch 23 to complete the hardware connection selection, and at the same time selects the axis-angle conversion mode in the CPU central processing unit 16 . The high-frequency pulse signal generated by the PWM generation module 15 of the TMS320F2808 white belt passes through the filter and buffer circuit 22 to generate a high-frequency sine wave signal, and the high-frequency sine wave signal is input into the resolver 10 as an excitation signal to make the resolver 10 start to work, and the sine and cosine encoding The two-way orthogonal voltage signal output by the resolver or the resolver 10 is introduced into the device by the differential receiver 11, processed by the comparator 12 to form a rough measurement pulse, which is integrated to the QEP module 13 of the TMS320F2808, and the result of the integration is given to the CPU module 16 of the TMS320F2808 . The analog signal is sampled, held and converted by the ADC module 14 that comes with TMS320F2808 to form a digital voltage signal to the CPU module 16, and the CPU module 16 performs an axis-angle transformation algorithm operation to obtain real-time angular position and angular velocity information, which is sent to the outside by the multi-channel interface Send message. The CPU module 16 completes the connection of the external control circuit board type circuit through the self-contained I/O module 17 in a parallel data interface mode or through the self-contained SPI module 18, and the CPU module 16 uses the self-contained general asynchronous serial interface A19 in a general-purpose The serial port mode outputs the conversion result to the monitoring software of the upper PC machine 8 . For the bus type interface requirements, the host PC 8 first sets the network address through software, and then the built-in universal asynchronous serial interface B20 or the built-in CAN communication interface 21 completes the level through 485 and the CAN interface level conversion circuit 6 Interface conversion, the obtained result is put into the industrial bus 9, and read by the master station.

Combined with Figure 3, the minimum system board hardware circuit mainly includes the power interface circuit, clock circuit, reset circuit, external interrupt circuit, and JTAG interface circuit of TMS320F2808. In the design of the power interface circuit, a large-capacity electrolytic capacitor (10μF here) needs to be installed on the power pin to provide large-capacity charge storage for the entire system, and several capacitors should be installed as close as possible to the MCU power pin. A 0.1μF ceramic bypass capacitor is used to suppress high-frequency noise; in clock circuit design, the present invention adopts an external clock mode, and a 12MHz quartz crystal oscillator and capacitor are connected to the EXTAL and XTAL pins to form a self-excited oscillation; the reset circuit is similar to the external interrupt, Generate a pulse signal to the corresponding pin by adding a button switch to the ground to realize manual reset or external interrupt; the JTAG interface unit circuit is a 14-pin plug for plugging in the background debugger.

Combined with Figure 4, the shaft-angle conversion part mainly completes the excitation signal generation and resolver signal processing functions. If the sensor is a sin-cosine encoder, the excitation part is not needed, and the excitation port may not be connected. The resolver needs an excitation signal of about 10KHz to work normally. The generation of the excitation signal is realized by PWM signal filtering and buffering. First, the PWM generator PWM1 and PWM2 jointly generate a bipolar PWM signal. The PWM signal is actively filtered and buffered. The circuit is restored to a high-frequency sine wave signal, and the high-frequency sine wave signal is input to the resolver through the terminal as an excitation signal. The analog signal generated by the resolver is a bipolar signal, which cannot be directly processed by the DSP. After level conversion and processing, it can be mapped to the DSP to process the unipolar level signal, and input to the ADC module pins ADCINA0 and ADCINB0 respectively.

Combined with Figure 5, the data communication unit uses the MAX485 chip as the RS-485 driver and RS-485 receiver to design the data communication unit. The matching resistance is selected as 120 ohms. U1 is used as the RS-485 drive terminal, and its RE and DE are connected to high level. U2 is used as the RS-485 receiving end, and its RE and DE are grounded. The TMS320F2808 chip is equipped with a serial communication interface SCI module. The SCI receiver and transmitter are double-buffered. Through a 16-bit baud rate selection register, the data transmission speed can be programmed in 65535 different ways. The circuit uses the driver chip MAX232 that complies with the RS-232 standard. Serial communication realizes the asynchronous communication between the PC and the multifunctional networked digital axis-angle conversion device. Using the TMS320F2808 processor to realize the node of the CAN bus, it is necessary to add a converter circuit between the CAN bus and the processor in order to achieve compatible level conversion. This system uses TI's SN65HVD230 converter (conforming to ISO11898) to realize the high-speed CAN bus network. SN65HVD230 is a 3.3V CAN transceiver, suitable for serial communication of CAN bus with higher communication rate, good anti-interference ability and high reliability. It has differential transceiver capability, the highest rate can reach 1Mb/s; low current waiting mode, typical current 370μA. It has 3 different working modes of high speed, slope and waiting. Its working mode can be selected through the Rs control pin. In order to reduce the electromagnetic interference caused by the rapid rise of the level, Rs is grounded through a 10kΩ resistor, which is selected as Slope control mode.

Claims (2)

1. A multifunctional networked digital shaft-angle conversion device is characterized in that: the composition mainly includes a sensor interface buffer circuit (2), a TMS320F2808 digital controller (3) and a serial-parallel data interface; the serial-parallel data interface further includes Parallel data output circuit (4), serial port level conversion circuit (5) and 485 and CAN bus interface (6); PC (8) is connected with TMS320F2808 digital controller (3) through serial port level conversion circuit (5), The initial hardware and software settings are completed through the software of the upper computer (8), including the setting of the shaft angle conversion method and the hardware connection setting; after the initial setting is completed and the hardware is connected, the angular position sensor (1) and the TMS320F2808 digital controller (3 ) transmit information through the sensor interface and buffer circuit (2), and complete the axis angle conversion operation in the TMS320F2808 digital controller (3), and the result obtained by the operation is transmitted to the control circuit board (7) by the parallel data output circuit (4), Either through the 485 and CAN bus interface (6) as an industrial control network node to transmit to the industrial bus (9), or through the serial port level conversion circuit (5) to be read by the monitoring program of the upper PC (8). 2. A multifunctional networked digital axis-angle transformation method is characterized in that: the host PC (8) carries out the hardware connection selection switch (23) to complete the hardware connection selection, and simultaneously carries out the axis angle in the CPU central processing unit (16) Conversion mode selection; the PWM generation module (15) that comes with the TMS320F2808 generates high-frequency pulse signals, which are filtered and buffered (22) to generate high-frequency sine wave signals, and the high-frequency sine wave signals are input to the resolver (10) as excitation The signal makes the rotary transformer (10) start working, and the sin-cosine encoder or the rotary transformer (10) outputs two-way quadrature voltage signals, which are introduced into the multifunctional networked digital shaft-angle conversion device by the differential receiver (11), and then passed through the comparator ( 12) Process and form a rough measurement pulse to integrate with the QEP module (13) that comes with TMS320F2808, and the result of the integration is sent to the CPU module (16) of TMS320F2808; the analog signal is sampled and held and converted through the ADC module (14) that comes with TMS320F2808 Form a digital voltage signal to the CPU module (16), and the CPU module (16) performs an axis-angle transformation algorithm operation to obtain real-time angular position and angular velocity information, and transmit information to the outside by a multi-channel interface; the CPU module (16) passes the self-contained The I/O module (17) completes the connection of the external control circuit board type circuit through the parallel data interface mode or by the SPI module (18) that comes with it, and the CPU module (16) connects it with the general-purpose serial port The way is to output the conversion result to the monitoring software of the upper PC (8); for the bus type interface requirements, the upper PC (8) first sets the network address through the software, and then the built-in universal asynchronous serial interface B20 or the built-in The CAN communication interface (21) completes the level interface conversion through the 485 and the CAN interface level conversion circuit (6), and the obtained result is put into the industrial bus (9) and read by the master station.

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