Study On Engineering Application Of PMSM Precision Servo

In this paper, the vector servo system of permanent magnet synchronous motor (PMSM) is researched on some specific technique problems in engineering application.First, in the hardware design, the method to power a multivoltage system and the method to interconnecting of multiple logic level in a system are summarized. The connections between TMS320F2812 and external extended 256K RAM is described, and the interface to AD converter AD7864 is designed. A DSP/MCU human-computer interface project is designed based on RS485 communication protocol and optical fiber transmission medium.Because the incremental photoelectric encoder doses not contain the information of absolute rotor pole position, the stationary accurate positioning of rotor pole when the motor is powered up is a challenge. Aimed at realizing this positioning, a stationary (nearly-no-move) positioning project is presented. It provides current vector of motor stator according to the imaginary original position, and reduces the judging range of rotor position according to the direction signal of incremental photoelectric encoder, and realizes accurate positioning. It makes the rotor back to the initial position while the test is proceeding, realizes accurate positioning finally.The errors of current measurement would be resulted from the way of current detection, and they can be divided into two categories: Offset errors and scaling errors. The errors of current measurement cause the periodic rotor speed ripples. In this paper, a new compensation algorithm is proposed.The principal feature of the proposed algorithm is the use of the integrator output signal of the d-axis PI current regulator. This output signal is nearly zero or constant because the d-axis current command is zero or constant, so that the maximum torque control or minimum reactive current control can be achieved. If the stator current includes offset errors and scaling errors, the integrator output signal of the d-axis PI current regulator ripples in the rotor speed of the same frequency. The proposed compensating algorithm for the current-measurement errors can be easily implemented by subtracting the DC offset value or rescaling the input measurement gain of the stator current.