Sensorless PMSM Start Control for Initial Speed and Direction
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Solution Overview
Problem
Existing sensorless field-oriented control (FOC) permanent magnet synchronous machines (PMSM) systems struggle to start smoothly due to insufficient consideration of initial rotation speed and direction, leading to potential start failures under various conditions.
Innovation Solution
A control method that identifies the initial rotation speed and direction of the PMSM, classifying it into five start modes (high-speed reverse, low-speed reverse, static, low-speed forward, high-speed forward, and static) to determine an optimal start mode, ensuring seamless transitions between control states using coordinate system projections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sensorless field-oriented control is used to reduce cost, then the system cannot obtain actual rotation speed and position information, but this leads to inability to guarantee smooth starting under various circumstances
Solution Approach 1:
The patent applies preliminary action by implementing a detection state before the start stage to acquire initial rotation speed and position information. This preliminary detection enables the system to prepare appropriate start parameters in advance, ensuring reliable starting without requiring expensive sensors throughout the entire operation.
Solution Approach 2:
The patent introduces an intermediary detection mechanism that temporarily captures rotation speed and position information during the detection state. This intermediary approach provides the necessary initial parameters for sensorless FOC to work reliably during starting, bridging the gap between cost reduction and starting reliability.
2Device complexity
If initial rotation speed is not considered in sensorless FOC starting, then the system is simpler, but this causes start failures under various circumstances
Solution Approach 1:
The patent segments the starting process into distinct stages: a detection state for acquiring initial rotation speed and position, and a start stage for executing the start command. This segmentation allows the system to obtain necessary initial parameters without complicating the overall sensorless FOC structure, maintaining simplicity while improving reliability.
3Reliability
If multiple start modes are implemented to handle various initial rotation speeds, then starting reliability improves, but control system complexity increases
Solution Approach 1:
The patent implements dynamic control by adjusting start parameters based on the detected initial rotation speed and position. The system dynamically selects appropriate start modes (such as different acceleration rates or initial current values) according to the actual initial conditions, enabling reliable starting across various circumstances without requiring a fundamentally complex control structure.
Data Source
AI summary
A control method, control apparatus and control system for an electric motor, and a computer-readable storage medium are provided. The control method for an electric motor includes: acquiring an initial rotation speed and an initial rotation direction of an electric motor; determining a target start mode for the electric motor according to the initial rotation speed and the initial rotation direction; and according to the target start mode, controlling the electric motor to start. A target start mode, which most conforms to an initial rotation speed and an initial rotation speed direction of an electric motor, can be determined from a plurality of preset start modes, so as to control the electric motor to start.