Motor Control Apparatus Back-EMF Phase Detection Threshold Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing motor control methods experience frequent switching between constant current control and vector control, leading to instability and increased motor sound or out-of-control states due to inaccurate rotation phase determination at low speeds.
Innovation Solution
A motor control apparatus that determines the rotation phase and speed of a rotor, using threshold values to switch between constant current and vector control modes, ensuring accurate phase determination and minimizing mode switching by maintaining vector control until the rotation speed drops below a certain threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If vector control is used to accurately determine rotation phase, then motor control precision is improved, but at low rotation speeds the induced voltage becomes insufficient leading to inaccurate phase determination
Solution Approach 1:
The patent changes the control parameter from induced voltage-based phase determination to back-EMF-based phase determination. By using the relationship between back-EMF and rotation speed, the system can accurately determine rotation phase even at low speeds where induced voltage is insufficient. This parameter change resolves the contradiction by finding an alternative measurement basis that remains effective across the full speed range.
2Adaptability or versatility
If switching between constant current control and vector control is performed based on rotation speed threshold, then control adaptability is improved, but frequent switching causes motor sound increase and out-of-control states
Solution Approach 1:
The patent implements feedback by continuously monitoring rotation speed and dynamically adjusting the control mode based on real-time conditions. The system uses feedback from the rotation phase determination accuracy and motor response to decide when to switch between control modes, preventing frequent switching by only transitioning when the feedback indicates stable operating conditions are met.
Solution Approach 2:
The control system transitions from static threshold-based switching to dynamic adaptive switching. The control mode selection is no longer based on a fixed speed threshold but on dynamic assessment of phase determination accuracy and motor response characteristics, allowing the system to adapt smoothly to changing operating conditions without frequent mode transitions.
3Device complexity
If constant current control is used at low rotation speeds, then phase determination simplicity is improved, but motor control precision and stability deteriorate
Solution Approach 1:
The patent changes the fundamental control parameter from simple constant current to back-EMF-based phase-aware control. By utilizing the back-EMF signal which is naturally present during motor operation, the system achieves precise phase determination without adding significant complexity. This parameter change enables reliable motor control at low speeds while maintaining practical system complexity levels.
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 reduces repetitive mode switching, stabilizes motor operation, and prevents out-of-control states by maintaining vector control until the rotation speed falls below a predetermined threshold, thereby minimizing motor sound and power consumption.
Implementation Method 1
the rotation phase of a rotor is determined based on induced voltage occurring in the winding of each phase of the motor in response to the rotation of the rotor
Implementation Method 2
a current component (torque current component) to generate torque used for rotating the rotor
Implementation Method 3
a current component (excitation current component) that affects the strength of a magnetic flux through the windings for control
Data Source
AI summary
A motor control apparatus operates in a first control mode in which the values of a torque current component and an excitation current component are controlled so that the difference between an instruction phase and a rotation phase is decreased and a second control mode in which constant current is supplied to a winding of a motor. The second control mode is switched to the first control mode if the rotation speed is varied from a value lower than a first threshold value to a value not lower than the first threshold value in the second control mode and the first control mode is kept even if the rotation speed is varied from a value not lower than the first threshold value to a value that is not lower than a second threshold value and that is lower than the first threshold value in the first control mode.