AC motor frequency conversion speed regulation is a high-tech technology in the field of power electronics and electrical transmission. High-power AC speed regulation is a key equipment for large-scale mechanical transmission such as rolling mills, hoists, traction and ship propulsion. It is also a national energy-saving Focus on promoting technology. Due to the complexity of the technology and the large equipment capacity, it involves many different fields such as power electronics, automatic control and motors. It has long been monopolized by a few large foreign companies, and my country's large-capacity AC speed-controlled transmission equipment has long been dependent on imports.
For the first time, the field-oriented control principle and system of doubly-fed motors with the goal of controlling torque was proposed, and a mathematical model for different field-oriented control AC motors was established.
For the first time, it was proposed that the field-oriented control principle of classical synchronous motors has the defect that the dynamic process flux linkage and torque control are not decoupled. It was pointed out that the field-oriented control synchronous motor is a transformer with state feedback of the flux linkage rotating coordinate system. Coefficient model, and the use of damping windings can offset the armature reaction of the dynamic process, improve the decoupling characteristics of flux linkage and torque control, and improve the field-oriented control theory of synchronous motors. At the same time, it is pointed out that the increment of shaft damping current is approximately equal to the increment of stator current at the moment of sudden load current addition, and a reasonable path must be set up for the shaft damping current, which guides the design and manufacturing of domestic high-power variable frequency synchronous motors.
Creatively put forward the damping flux directional control theory of AC variable frequency synchronous motor. It is pointed out that the damped flux directional control synchronous motor has exactly the same steady-state characteristics as the air gap flux directional control. The damped flux is more resistant to disturbance and easier to observe, which improves the dynamic performance of the system and is suitable for the main drive application of rolling mills. Successfully developed a damped flux observer. For the first time, the initial positioning technology of the synchronous motor rotor and the engineering adjustment principle and method of the synchronous motor field-oriented control system were proposed, which replaced the usual motor simulator debugging. The adjustment is accurate and easy to operate. It has been used in engineering practice and has obtained the Chinese invention patent and the national First Prize of the Science and Technology Progress Award of the Education Commission (first place).
Using a new modeling and simulation theory oriented to functional structure diagrams, a simulation platform for visual motors and power electronic systems was established, laying a foundation for the research and engineering design of high-power AC speed control technology.
For the first time, the transient power theory is introduced into the field-oriented control system of AC variable frequency synchronous motor, and the theory and analysis method of the integrated system of power grid, frequency converter, motor and control system are proposed. The mathematical relationship between system characteristics, reactive power and harmonics was established, and methods to control reactive power impact and harmonic pollution of AC speed control systems were proposed.
For the first time, the mechanisms of AC speed control motor vibration, load periodic changes, and load impact oscillation were analyzed, and an anti-disturbance robust load observer was developed using modern control theory, thus solving a large number of problems. Problems with electromechanical vibration of power rolling mill transmission AC speed regulation.
For the first time, a simulation model of IGBT/IGCT high-power power electronic devices was established, and multi-level inverter IGCT clamping and circuit topology theory and design methods were proposed; greatly improving the performance of domestic IGCT high-power inverters. output capacity.