Synchronous Machine Control via Polar Coordinate Transformation
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Solution Overview
Problem
The high computational intensity and implementation effort required for controlling permanently excited synchronous machines due to the need for complex transformations between rotor- and stator-related variables, as well as the necessity for multiple phase current sensors, pose a challenge in efficiently regulating these machines.
Innovation Solution
The use of polar coordinate representation for control, which transforms setpoint torque and rotor speed into polar coordinate values (radial and angular components) to simplify the control process, eliminating the need for complex Clarke and Park transformations and reducing the requirement for multiple phase current sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex transformations (Clarke and Park transformations) are used to control the synchronous machine, then precise control of rotor and stator variables is achieved, but computational intensity and implementation effort increase significantly
Solution Approach 1:
The patent transforms the control variables from Cartesian coordinates (d/q components) to polar coordinates (magnitude and angle). This parameter change simplifies the control equations by eliminating the need for complex Clarke and Park transformations, reducing computational intensity while maintaining control precision through the direct relationship between voltage magnitude, angle, and machine output.
2Measurement precision
If multiple phase current sensors are provided for all three phases, then accurate detection of stator currents is achieved, but hardware complexity and cost increase
Solution Approach 1:
The patent extracts only the necessary current information from the three phases by utilizing a single phase current sensor combined with the polar coordinate transformation approach. The control system determines the required current magnitude and angle from the torque setpoint and speed, eliminating the need to directly measure all three phase currents while maintaining sufficient control accuracy.
3Speed
If conventional vector control with d/q representation is used, then dynamic performance is maintained, but the control system requires complex transformation calculations and multiple sensors
Solution Approach 1:
Instead of transforming stator variables to rotor variables (conventional approach), the patent inverts the approach by directly determining rotor voltage magnitude and angle from torque and speed setpoints using polar coordinate representation. This inversion eliminates the need for complex transformations and multiple sensors while maintaining dynamic performance through direct control of the voltage vector.
Data Source
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AI summary
The present invention comprises a method and a device for controlling or regulating a permanently excited synchronous machine (50), having the steps for receiving a desired torque value (M_soll) and recording a rotor speed value (N_ist) of the synchronous machine; transforming the received desired torque value and the recorded rotor speed value into a desired polar coordinate value (U_soll, Phi_soll) on the basis of a predefined transformation assignment (10, 11, 12); determining a control data record (SD_U, SD_V, SD_W) from a predefined control data table (30) on the basis of the desired polar coordinate value (U_soll, Phi_soll); and controlling energization of the synchronous machine on the basis of the control data record determined so that the synchronous machine generates a desired torque corresponding to the desired torque value in the steady state thereof.