Magnetic Pole Position Estimation Reducing Rotor Movement
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Solution Overview
Problem
Existing methods for magnetic pole position estimation in electric motors face challenges in accurately controlling motor movement when the recognized magnetic pole position differs from the actual position, leading to potential misdirection and excessive movement, especially when using step-like current commands and improper speed controller gains.
Innovation Solution
The method adjusts the magnetic pole position error angle by applying a q-axis current in the opposite direction of the actual d-axis, gradually rotating the recognized magnetic pole position to match the actual position, using a control device to manage the q-axis current command and reduce movement amount through precise estimation and adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a step-like current command is applied for magnetic pole position estimation, then the estimation process can be initiated, but the motor movement amount becomes excessive when the magnetic pole position is displaced by 180 degrees
Solution Approach 1:
The patent implements dynamic adjustment of the speed controller gain during magnetic pole position estimation. The gain is set to a first value during initial estimation and changed to a second value (lower than the first) when the estimated position is far from the actual position, preventing excessive motor movement while maintaining estimation capability
Solution Approach 2:
The patent changes the speed controller gain parameter based on the magnetic pole position estimation state. By dynamically adjusting this control parameter, the system prevents excessive movement when large position errors exist while maintaining effective estimation when position errors are small
2Device complexity
If the speed controller gain is not properly set, then the control system remains simple, but the speed limit command is not controlled properly and motor movement becomes excessive
Solution Approach 1:
The patent makes the speed controller gain dynamic rather than fixed. The gain automatically adjusts based on the magnetic pole position estimation accuracy, providing proper speed control without requiring complex manual tuning or overly sophisticated control algorithms
3Extent of automation
If the magnetic pole position recognized by the control device differs from the actual magnetic pole position, then the control device can operate independently, but the electric motor may be driven in the opposite direction or move beyond the desired position
Solution Approach 1:
The patent implements feedback through magnetic pole position estimation. The control device continuously estimates the actual magnetic pole position and uses this information to correct control commands, ensuring the motor operates in the correct direction and reaches the desired position even when initial position recognition is inaccurate
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables accurate magnetic pole position estimation and control, reducing the electric motor's movement amount and ensuring precise operation by aligning the recognized and actual magnetic pole positions, thus preventing excessive movement and improving speed control.
Implementation Method 1
a q-axis current in a q-axis direction is applied to the electric motor 1
Data Source
Figure 1
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AI summary
The purpose of the present invention is to reduce the amount of movement of a rotor during estimation of a magnetic pole position of an electric motor. Provided is a magnetic pole position estimation method provided with: a first step of setting an initial position of a magnetic pole; a second step of increasing a q-axis current command value gradually, and detecting an operating direction and the amount of movement of the rotor; a third step of causing the magnetic pole position to be rotated toward 180 degrees in a positive direction when the operating direction is positive, and causing the magnetic pole position to be rotated toward 180 degrees in a negative direction when the operating direction is negative; a fourth step of storing the magnetic pole position when the amount of movement has become zero in the third step as an actual measurement magnetic pole position of the rotor; and a fifth step of storing a magnetic pole position obtained by rotating the actual measurement magnetic pole position by -90 degrees as a control start position.