In order to improve fertilization uniformity of an integrated fertilizer dissolving and mixing device, and solve the problem in comprehensive control of irrigation quantity and fertilizer concentration during regulation of water and fertilizer, in this paper, an automatic control system for the integrated water fertilizer dissolving and mixing device was designed. STM 32 micro controller was used as the control core, the relationship between mass concentration and electrical conductivity of the fertilizer solution was determined by calibration experiments on fertilizer concentration. The fertilizer outlet concentration was detected in realtime by online with conductance electrodes and a related detection circuit. The mass concentration signal of fertilizer solution was fed back to the processor, and a control signal was generated, thus a closedloop control was constructed. A halfbridge circuit was adopted to drive a DC pump to regulate water flow, and the PWM pulse width modulation method was used to change solid fertilizer feeding rate inreal time, resulting an even more uniform and stable fertilizer outlet concentration. The fertilization performance of the device was tested; the result shows that the uniformity coefficient of water and fertilizer solution is increased by 31.46% after the control system in adjusted in realtime.
XIA Hua-Meng,LI Hong,CHEN Chao et al. Development of automatic control system for integrated fertilizer dissolving and mixing device[J]. Journal of Drainage and Irrigation Machinery Engin, 2019, 37(1): 80-85.