Sensorless Motor Rotation Control With Open-Loop to Closed-Loop Switching
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Solution Overview
Problem
Existing sensorless control methods for permanent magnet synchronous motors face reliability issues due to changes in rotor direction, which can lead to equipment damage and reduced operational stability, particularly in applications requiring unidirectional rotation.
Innovation Solution
A forward and reverse rotation control circuit and method for sensorless motors, incorporating a logic controlling module, rotor angle calculating and estimating modules, and a selecting module, to ensure consistent rotor direction by using configuration parameters and control signals to manage angular increments and transitions between open-loop and closed-loop control modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If sensorless control method is used for permanent magnet synchronous motors, then the control system becomes simpler and more cost-effective, but reliability deteriorates due to rotor direction changes
Solution Approach 1:
The patent implements feedback mechanisms by continuously monitoring the rotor angle through estimation algorithms and comparing it with expected values. The control system uses the estimated rotor position feedback to adjust control signals, ensuring accurate rotor direction control without mechanical sensors, thus maintaining reliability while keeping the system sensorless.
Solution Approach 2:
The patent changes control parameters dynamically by switching between open-loop asynchronous forced-dragging mode for starting and closed-loop control for normal operation. This parameter change approach allows the system to achieve reliable rotor direction control adaptively, preventing unwanted direction changes while maintaining simplicity.
2Speed
If open-loop asynchronous forced-dragging mode is used for starting, then the motor can start at low speeds, but rotor direction control becomes unreliable
Solution Approach 1:
The patent applies preliminary action by using open-loop asynchronous forced-dragging mode specifically for the starting phase to bring the motor to operational speed, then transitions to closed-loop control for reliable direction control. This preliminary action ensures the motor can start without the complexity of closed-loop control at very low speeds.
Solution Approach 2:
The patent implements dynamics by dynamically switching control modes based on operating conditions. The system transitions from open-loop forced-dragging mode during startup to closed-loop control when the motor reaches sufficient speed, adapting the control strategy to maintain reliability while enabling low-speed starting capability.
3Measurement precision
If closed-loop control is used after reaching certain speed, then control precision improves, but the system becomes more complex
Solution Approach 1:
The patent applies segmentation by dividing the control process into distinct phases: open-loop forced-dragging mode for starting and closed-loop control for normal operation. This segmentation allows the system to use simpler control during startup and more precise control during operation, avoiding the need for complex closed-loop control throughout the entire operating range.
Data Source
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AI summary
Provided in the present application are a forward and reverse rotation control circuit for a sensorless motor, a method and a motor controller. According to one example of the present application, a forward and reverse rotation control circuit comprises: a logic controlling module, used for providing configuration parameters and control signals, wherein the configuration parameters comprise a forced dragging angle increment and a forced dragging angle initial value, and the control signals comprise a forward and reverse rotation control signal and a selection signal; a rotor angle calculating module, used for receiving the forced dragging angle increment and the forced dragging angle initial value, so as to obtain a rotor angle calculation value by accumulation; a rotor angle estimating module, used for estimating an angle increment on the basis of voltage and current signals of a motor, and limiting an angle increment estimated value on the basis of the forward and reverse rotation control signal, so as to obtain a rotor angle estimated value by accumulation; and a selecting module, used for selecting, on the basis of the selection signal, to control the motor according to the rotor angle calculation value or the rotor angle estimated value.