PMSM Magnetic Pole Position Detection at Low Rotating Speeds
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Solution Overview
Problem
Existing methods for determining the magnetic pole position of a permanent-magnet synchronous motor, such as the double-pulse method and d-axis current peak value accumulation, suffer from inaccuracies and long processing times, especially at low rotating speeds, which can lead to incorrect rotor direction and system failure.
Innovation Solution
A magnetic pole position determining system that applies a high-frequency voltage to the motor's direct axis, uses a zero voltage vector pulse to determine the current vector position, and employs a mapping table to accurately identify the magnetic pole position based on time differences and rotor speed, enabling quick and precise determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing methods such as double-pulse method or d-axis current peak value accumulation are used to determine magnetic pole position, then the determination process can be implemented, but the determination accuracy is low and processing time is long, especially at low rotating speeds
Solution Approach 1:
The system applies a high-frequency voltage to the motor before the zero voltage vector pulse to preliminarily determine the magnetic pole initial position and rotating speed. This preliminary action provides accurate initial conditions that enable subsequent rapid and accurate magnetic pole position determination, solving the contradiction between measurement precision and processing time by preparing the system in advance with high-precision data.
2Reliability
If existing methods are used at low rotating speeds, then the motor can operate, but incorrect rotor direction and system failure occur due to inaccurate magnetic pole position determination
Solution Approach 1:
The system changes the parameter of voltage vector type by applying a zero voltage vector pulse after high-frequency voltage injection. This parameter change enables the system to overcome the limitations of existing methods at low rotating speeds, achieving accurate magnetic pole position determination and preventing incorrect rotor direction and system failure, thereby improving reliability without sacrificing measurement precision.
3Measurement precision
If a zero voltage vector pulse is applied after high-frequency voltage, then accurate magnetic pole position can be determined, but the control process becomes more complex
Solution Approach 1:
The system uses periodic action by applying voltage vectors at specific time points (first time point for high-frequency voltage, second time point for zero voltage vector pulse). This periodic control strategy achieves accurate magnetic pole position determination through clearly defined control stages, making the process manageable despite increased complexity. The time-point-based control structure organizes the complex sequence into discrete, repeatable operations.
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
The system provides accurate and rapid identification of the magnetic pole position, improving reliability and reducing the risk of rotor misidentification, even at low speeds, thereby enhancing the performance of sensorless vector control systems.
Implementation Method 1
apply a high-frequency voltage to a direct axis of a two-phase rotating coordinate system of the motor
Implementation Method 2
apply a zero voltage vector pulse to the motor at a second time point; determine a current vector position angle corresponding to the zero voltage vector pulse
Data Source
AI summary
The present disclosure provides a magnetic pole position determining system, including a motor and a magnetic pole position determining apparatus. The motor includes a rotor. The apparatus is configured to: apply a high-frequency voltage to a direct axis of a two-phase rotating coordinate system of the motor at a first time point; determine a magnetic pole initial position of the rotor and a rotating speed of the rotor based on the high-frequency voltage; apply a zero voltage vector pulse to the motor at a second time point; determine a current vector position angle corresponding to the zero voltage vector pulse; and determine a magnetic pole position of the rotor based on the first time point, the second time point, the rotating speed of the rotor, the current vector position angle, a preset mapping table, and the magnetic pole initial position.