Abstract : This article mainly introduces the synchronous control of multiple motors in an automated production line using communication between a microcontroller and a frequency converter. The hardware configuration and software programming of the control are described. An AT89S51 microcontroller is used as the controller, and a domestic Jialing JP6C frequency converter is used as the actuator to control the motors. In practical applications, this method can well meet production needs. Keywords : Motor group; Synchronous control; Frequency converter; Microcontroller 0 Introduction With the continuous improvement of AC speed regulation technology and the continuous development of frequency conversion technology, more and more manufacturers are choosing to use frequency converters for speed regulation. This speed regulation method has rigid mechanical characteristics, good speed regulation smoothness, wide speed regulation range, and saves energy, belonging to green speed regulation. A production line is often driven by multiple motors, but due to different mechanical transmission ratios and inconsistent motor characteristics, maintaining the synchronized pace of the motor-driven production line requires that the linear speed of the impeller driven by each motor be the same, which brings great difficulties to speed regulation. This article introduces a synchronous control method using the communication of a frequency converter. It is convenient to adjust the running speed of the entire production line and can always keep the pace of the entire production line consistent. This paper uses AT89S51 microcontroller as controller and domestic Jialing JP6C frequency converter as actuator to control the motor, and configures buttons and LCD display. During operation, the microcontroller program calculates the running frequency of each motor according to the input ratio, and the microcontroller communicates with each frequency converter to transmit and control the running frequency of each motor. 1 Hardware Design The hardware of this system mainly consists of frequency converter, microcontroller, LCD display and communication, as shown in Figure 1. (1) Frequency Converter The frequency converter adopts the relatively inexpensive domestic Jialing JP6C frequency converter. This frequency converter adopts the fourth generation IGBT, PIM module 16-bit microcontroller and torque vector control technology, and has the advantages of high output torque, low noise, built-in PID control function, communication control mode, automatic energy saving operation, and very convenient communication control with microcontroller. (2) The microcontroller uses the AT89S51 microcontroller, which is a low-power, high-performance, and low-cost CMOS 8-bit microcontroller. It contains 4 KB of rewritable Flash read-only program memory and is manufactured using ATMEL's high-density, non-volatile memory technology. It is compatible with the standard MCS-51 instruction set and 8OC51 pin structure. The chip integrates a general-purpose 8-bit central processing unit and ISP Flash memory, 128 B of random access data memory, 32 external bidirectional input/output (I/O) ports, 5 interrupt priority levels with 2-level nested interrupts, 2 16-bit programmable timer/counters, 2 full-duplex serial communication ports, a watchdog (WDT) circuit, and an on-chip clock oscillator. Therefore, the system hardware design is simple and the software design is very convenient. (3) The display uses the EDM-2002A character dot matrix LCD display component. This component can display two lines of information, each containing 20 characters. The upper line displays the time and the set frequency of the main motor, and the lower line displays the proportional coefficient of each motor. The connection between the LCD display assembly and the microcontroller is achieved through the I/O port. P0.0 to P0.7 provide data signals, and P2.0 to P2.2 provide control signals. The timing coordination between the LCD display assembly and the microcontroller is completed by software. (4) Memory In order to store the modified proportional coefficient and manage and query the parameters of the production line, the AT24C02 chip of the American ATMEL company is used. This chip is a low-power CMOS serial E. PROM chip, containing 256×8-bit storage space, with the characteristics of wide working voltage (2.5~5.5 V), many erase and write cycles (greater than 10,000 times), fast writing speed (less than 10 ms), and two-wire communication. The communication timing with the microcontroller is completed by software. (5) Keyboard The keyboard uses 6 keys. The first key is used to control the motor to run or stop. The other 5 keys are defined as plus, minus, left shift, confirm, and return, respectively, in conjunction with the display of running frequency and function control, etc. Full text download: Synchronous control of motor group frequency conversion speed regulation