Motor Rotor Position Control Using d-q Current Correlation
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Solution Overview
Problem
Conventional motor drive devices take a significant amount of time for the rotor to reach its designated position, especially when there is a large angular displacement, which can lead to inefficiencies and potential loss of synchronization.
Innovation Solution
A motor drive device that includes a motor, an inverter, and a control device performing coordinate transformation of currents into d and q axis currents, calculating a correlation value based on these currents to control the rotor's position, using PID control to reduce the time for the rotor to align with the designated position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional initial operation is performed to set rotor position to designated position, then position control is achieved, but it takes a significant amount of time when there is large angular displacement
Solution Approach 1:
The patent implements feedback control by calculating a correlation value from the relationship between d-axis current and q-axis current, then using this correlation value to determine the rotor's actual position. The control device continuously compares the actual position with the designated position and adjusts the current commands to minimize the difference, enabling rapid and accurate position control even when large angular displacement occurs during initial operation.
Solution Approach 2:
The patent changes the control parameters by using correlation value calculation based on d-axis and q-axis currents to estimate rotor position. This parameter transformation allows the system to quickly determine rotor position without relying on traditional methods that are slow when large angular displacement occurs, thereby reducing the time loss while maintaining position control accuracy.
2Measurement precision
If conventional position control method is used, then rotor position can be controlled, but control accuracy is insufficient and synchronization loss may occur
Solution Approach 1:
The patent implements feedback control by calculating a correlation value from the relationship between d-axis current and q-axis current, then using this correlation value to determine the rotor's actual position. The control device continuously compares the actual position with the designated position and adjusts the current commands to minimize the difference, enabling rapid and accurate position control even when large angular displacement occurs during initial operation.
Solution Approach 2:
The patent performs preliminary position estimation by calculating the correlation value between d-axis and q-axis currents before executing the position control operation. This preliminary action allows the system to quickly determine the rotor's initial position and plan the control strategy accordingly, preventing synchronization loss and improving control accuracy from the outset.
Data Source
AI summary
A motor drive device includes a motor having a rotor, and a control device that controls the motor. The control device calculates a first value based on a d axis current and a q axis current of the motor. The control device calculates a second value by integrating the first value. The control device calculates a third value by performing prescribed control for making the second value equal to zero. The control device performs, based on the third value, position control for causing a rotational position of the rotor to match a designated position.