Open-loop starting strategy based on power angle self-balancing characteristic

Abstract

The invention relates to an open-loop starting strategy based on a power angle self-balancing characteristic. The strategy comprises the steps that a speed loop and a current loop are in an open-loopcondition, d-axis voltage is U<d><*>=U<align><*>, U<align><*> is aligned expected voltage, q-axis voltage U<q><*> is 0, and an expected position angle theta is 0 to 90 DEG; a voltage vector which is 90 degrees different from the expected position angle is applied, and the rotor is rotated to the expected position angle; the d-axis expected voltage is removed, and an open-loop starting stage is entered; a speed loop is in an open loop, a current loop is in a closed loop condition, d-axis expected current I<d><*> is 0, q-axis current Iq is added to the expected maximum current I<qmax><*>, and anexpected acceleration, an angular velocity and an angle are as described in the specifications; the q-axis current Iq is kept as the expected maximum current I<qmax><*>, if the angular velocity is greater than the minimum observation velocity wmin, an observer is started; and the q-axis current Iq is reduced from the expected maximum current I<qmax><*>, the angle and the angular velocity observedby the observer are compared with the expected angle and angular velocity, a switching threshold value is met, and closed-loop switching is carried out. According to the open-loop starting strategy,the defects of poor applicability, torque pulsation during starting and switching and the like of an existing motor under a low-speed condition are overcome.

Description

technical field [0001] The invention relates to the technical field of speed sensorless control of permanent magnet synchronous motors, in particular to an open-loop starting strategy based on power angle self-balancing characteristics. Background technique [0002] Permanent magnet motor has the characteristics of high efficiency, high power density, good control performance and low maintenance cost, so it has a wide range of applications. It is used in various fields such as aerospace, national defense, industry and agriculture, production and daily life, and has gradually become a motor drive system. Workhorse for precision servo and electric vehicle applications. [0003] In the motor control strategy, in order to obtain real-time and accurate position information, it is generally necessary to install position detection devices such as Hall position sensors, resolvers or photoelectric encoders. These sensors usually have high precision and response speed, but at the sam...

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Problems solved by technology

[0006] Purpose of the present invention: In order to overcome the defects in the prior art, such as poor applicability of the motor under low-speed conditions and torque ripple during start-up and switching, the present invention provides an open-loop start-up strategy based on power angle self-balancing characteristics , greatly reducing torque ripple and improving system robustness

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