Phase compensation method and device for motor zero position and encoder zero position
In the era of Industry 4.0, the state focused on upgrading manufacturing and developing high-end intelligent equipment. Servo control systems play a pivotal role as direct performers in automation and high-end smart equipment. Permanent Magnet Synchronous Motors (PMSM) have been used in CNC machine tools, robots, manned spacecraft, inverter air conditioners, etc. due to its high efficiency, high air gap magnetic density, high power factor, compact structure, and linear response. The occasion is widely used [1]. In the servo drive control system, can the accuracy of the phase relationship between the servo motor zero and the encoder zero can be accurately obtained, and the servo motor can start normally. The wrong phase relationship will cause the PMSM to fail to start, causing the rotor to reverse and shake. Other undesirable phenomena [2].
In order to accurately obtain the phase relationship between the zero position of the servo motor and the zero position of the encoder, Liu Jianwen summarized the different phase alignment methods of various encoders. These methods are mainly manual alignment, and the basic steps of alignment are [3]:
(1) Directly input direct current to any two phases of the motor to lock the motor rotor at a fixed position. The electrical angle of the locked position of the motor rotor can be determined according to the phase sequence and direction of the energization. For example, if the direct current is driven by the a-phase winding of the motor and the b-phase is wound out, the motor rotor is locked at a position where the electrical angle is equal to -30°.
(2) Manually adjust the relative position of the encoder and the motor rotor, and use the debugging tools, such as an oscilloscope, a device that can display the encoder feedback data, observe the encoder zero mark, when the zero mark appears on the debugging tool. , the encoder shaft is fixed on the rotor of the motor to complete the phase alignment.
This manual search and calibration of the zero position is very laborious and affects the consistency of the calibration accuracy of the corresponding encoder zero. Thus, various zeroing devices have been developed for different encoder designs. Wang Xinshe et al. Designed a phase-aligned servo driver for incremental encoders with UVW Hall signals. Using multiple selector switches to control the phase alignment step, using multiple LEDs to display signal states, the encoder phase and rotor can be arbitrarily adjusted. The magnetic pole phase corresponds to the position, and the motor can be dragged. The operation is relatively simple, and the production efficiency and phase accuracy are improved. However, it is verified whether the signals of the encoder are correct before the zero calibration, and the zero calibration result is not verified. [4] ]. Zhang Jingbo et al designed a dedicated zero-adjuster that supports incremental and absolute encoders. The interface is friendly and the parameters can be set. However, it is not verified whether the encoder signals are correct before the zero calibration, and the zero calibration results are not performed. Verification [5]. Therefore, the existing zero adjustment device still has some improvements. This paper mainly improves the phase compensation method for the absolute encoder motor zero and encoder zero.
