Dynamics of the Servo Drive Brushless DC Motor in the Auto Switching Mode

In his study of the dynamic response of a servo valve motor the author substantiated the conditions of transition to the coordinates of the rotor and provided a mathematical description of the valve motor as a Brushless Direct Current Motor (BLDC). The mathematical description of the valve drive (VD) in the rotor (d, q) system of coordinates makes it possible to establish conditions presenting VD as a structure, similar to a direct-current motor (DC-motor). The vector control systems can be implemented by means of converters of coordinates, mathematical models and multiple-loop systems of the subordinated regulation. The vector control systems of the valve actuator ensure its functioning in a wide range of speeds and are used in precision mechanisms. However, the mathematical model describing the system of the rotating coordinates defines increased requirements to the effective control system. Moreover, this principle assumes a withdrawal from a discrete character of switching and establishment of sine-wave voltage and currents in the motor winding. It is important to point out, that a mathematical model of the rotating coordinates does not allow an unequivocal description of the specified structural presentations to define the control valve drive as a reversed DC motor. Firstly, it is defined by the duality of the processes and presence of a commutator functioning as collector, and, secondly, by the rotor position sensor (RPS) functions of the coordinates converter. Therefore, an adequate estimation of the valve drive properties requires models and structures taking into account the discrete switching and nonlinear properties of the controlled object. A block diagram of the servo drive displays the switching processes and formation of the anticipatory switching angles. The research provided a foundation for a simplified block diagram of the valve motor working in BLDC mode and synthesis of the regulators of the double-loop servo system. The dynamic modes of the drive were tested using the bottom and top speeds of the control range in a system with software setters of the angle and speed. It was demonstrated that depending on the operating conditions BLDC possessed dual properties: of a synchronous machine and of a motor of direct current. The dynamic and static characteristics of the valve motor working in the mode of auto switching are prominent features of the designed-system making it comparable with the vector control systems of the synchronous machines with the field oriented control (FOC).

следящий электропривод, синхронная машина, обращенная машина постоянного тока, БДПТ, ПИД регулятор, программный задатчик скорости и угла, servo drive, synchronous machine, reverse DC machine, BLDC, PID regulator, program speed and angle setting device

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