Abstract : A specific design scheme for the main circuit and control circuit of the frequency converter is proposed. Automatic tracking of the speed of the permanent magnet synchronous motor (PMSM) is achieved using the output current. Adaptive U/f curve control of the PMSM is realized by adopting high power factor control. The grid-connected control of the PMSM is studied. The stator voltage phase of the PMSM is estimated according to the load conditions. The experimental test curve shows that the stator voltage curve transition is smooth and basically without impact during the grid connection process. A prototype experiment was conducted on the frequency converter of the PMSM, and the results show that the performance is good and can fully meet the requirements of the PMSM in the oil pumping unit. Keywords : permanent magnet synchronous motor; frequency converter; high power factor Adaptive U/f control is implemented through high power factor control. The dconnected control of the PMSM is studied by estimating the voltage phase of the PMSM stator under different loading conditions. The experimental test shows that the stat voltage curve is smooth during grid connection without any impact. A prototype experiment of the PMSM transducer is conducted. The results demonstrate good performance and meet the requirements of the PMSM in the pumping unit. Keywords: permanent magnet synchronous machine (PMSM); transducer; high power factor. High-magnetic-field permanent magnet motors (PMSMs) possess significant advantages such as small size, low weight, low inertia, fast response, high torque/inertia ratio, high speed/weight ratio, high efficiency, high starting torque, high power factor, energy saving, and reliable operation. To achieve high-performance control, a speed control system for a permanent magnet synchronous motor based on the TMS320F2407 control core was designed. 1. Main Circuit Design and Control Circuit The main circuit adopts a voltage-type AC-DC-AC structure, as shown in Figure 1. It utilizes a three-phase uncontrolled full-bridge rectifier module for rectification, and an IGBT module for inverter operation. The IGBT driver module is Fujifilm's EXB841. Due to design flaws in this module, IGBT burnout frequently occurs. After multiple experiments, it was found that: 1) The main reason for the damage to the 5V Zener diode built into the EXB841 is that its transient power consumption is much greater than its rated power consumption at the moment of outputting the forward gate voltage; 2) The dynamic performance of the 5V reverse gate voltage generated by the Zener diode is poor. Connecting a (+15V) and (+5V) Zener diode in series between the (+20V) power supply can quickly turn off the IGBT; 3) Increasing the gate drive resistor R helps reduce transient power consumption, but the dynamic performance of the drive gate voltage must also be considered. [b][align=center]For more details, please click: Permanent Magnet Synchronous Motor Variable Frequency Speed ​​Control System[/align][/b]