Development and testing of a motor drive and control unit based on the field-oriented control algorithm for the seed-metering device

Abstract

Good planting quality is the basis for high and stable crop yield. The performance of the seed-metering device is an essential factor affecting the planting quality. For the drive system of the seed-metering device with the motor as the power source, the working performance of the motor directly affects the seed-metering quality. A high-performance electric drive system should be able to provide stable torque and precise speed for the seed-metering device. However, it is not clear whether the motor can always maintain good speed control performance and torque stability under different working parameters (speed, load) of the seed-metering device. And the working performance of the motor is affected by the control algorithm. It is also unknown whether the motor control algorithm will affect the working performance of the motor, resulting in changes in the seed-metering quality of the seed-metering device. Aiming at the above problems, a motor drive and control unit based on the field-oriented control (FOC) algorithm was developed in this study. The variation law of the motor speed control performance and torque stability with the target speed and load under different control algorithms (square-wave control (SWC) and FOC) were explored. A comparison test of the seed-metering quality between the SWC algorithm and the FOC algorithm was carried out to determine the influence of the motor control algorithm on the seed-metering quality. The research shows that with the increase in target speed of the seed-metering device, the rise time and settling time tend to increase gradually. The motor speed response performance decreases with the increase in target speed of the seed-metering device. The average overshoot, average rise time, and average settling time of the five motor speeds under the FOC algorithm (10.43%, 0.44 s, 0.43 s) were less than the SWC algorithm (15.68%, 0.67 s, 0.95 s). The torque stability of the motor increases with the target speed and load. Torque ripple decreases with the increase in target speed and load level. The torque ripple of the FOC algorithm was always smaller than that of the SWC algorithm. With the increase in target speed and load level, the difference in torque ripple between the two control algorithms is gradually reduced. Compared with the SWC algorithm, the FOC algorithm had better speed control performance and torque stability. The motor control algorithm has a significant impact on the seed-metering quality. The average quality of feed index (QFI), average miss index (MI), and average coefficient of variation (CV) of the SWC algorithm were 98.58%, 1.05%, and 16.29%, respectively. The average QFI, average MI, and average CV of the FOC algorithm were 98.85%, 0.83%, and 14.59%, respectively. The seed-metering quality under the FOC algorithm was better than the SWC algorithm. The seed-metering quality of the electric drive seed-metering system can be improved by optimizing the motor control algorithm.