Direct torque control was proposed for asynchronous motors in the mid-1980s. This method avoids the complex coordinate transformation in vector control. The stator flux estimation only involves the stator resistance and weakens the dependency on the motor parameters. In view of the advantages of direct torque control, some scholars are currently devoted to the expansion of the control method on synchronous motors, and initially achieved the direct torque control of permanent magnet synchronous motors. This project was supported by the National Natural Science Foundation of China (50077018) and the Ministry of Education. Special fund for scientific research funded project for doctoral disciplines (20020613010 Direct torque control is simple and dynamic performance is excellent. The accuracy of stator flux observation directly affects the performance of the control system. The structure is simple in the direct torque control system. The pure integrator to estimate the stator flux linkage simplifies the system structure and reduces the dependence on the motor parameters. However, since the integral integrator observation method has an integral initial value problem, that is, if the initial value of the sinusoidal input signal is not a peak value, the integral As a result, a DC offset is superimposed on the cosine signal, and since the pure integrator has no inhibitory effect on the DC component of the input signal, even a small DC component will eventually cause the integrator to saturate. The improved flux observation method is used to improve the accuracy of the flux observation, but It is because many improvements greatly increase the complexity of the observation link, thereby weakening the advantages of the simple direct torque control structure.Therefore, JunHu proposed three improved integrators for the observation of the stator flux linkage of an induction motor, which not only effectively improves the stator The accuracy of the flux observations and inherits the advantages of simple integrator structure.
For the permanent magnet synchronous motor because of the initial excitation on the rotor, if the pure integrator continues to be used, it will inevitably cause inaccurate observation of the stator flux linkage, resulting in a decrease in the performance of the entire control system. In this paper, the second improved integrator proposed by JunHu et al. for induction motor flux linkage is introduced into the direct torque control of permanent magnet synchronous motor. According to the deficiencies of the integrator in the application of the system, a modification scheme is proposed. .
2 Based on the observation of the PMSM direct torque control stepper stator flux of the improved integrator, a second improved integrator was selected for observation of the stator flux linkage in the permanent magnet synchronous motor direct torque control system. .
2.1 The structure of the improved integrator and its detailed explanation in response to its operating principle are provided in the description. The main idea of ​​this integrator can be
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