Motor Control Phase Determination During Mode Switching
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Solution Overview
Problem
Motor control stability is compromised during mode switching from vector control to constant current control or vice versa, particularly at low rotation speeds, due to fluctuations in rotation speed and inaccurate phase determination.
Innovation Solution
A motor control apparatus that includes a detector for driving current, a phase determiner to determine the rotation phase, and a controller with two modes: one for phase feedback control and another for constant current control, where the phase determiner continues to determine the rotation phase during constant current control, and the instructed phase is adjusted based on the determined phase during mode switching to maintain stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If vector control is used to reduce phase difference between instructed phase and rotation phase, then motor control precision is improved, but at low rotation speeds the induced voltage becomes too small for accurate phase determination
Solution Approach 1:
The system performs preliminary action by continuously determining the rotation phase even during constant current control mode, so that when switching to vector control, the phase information is already available. This prevents the loss of phase determination capability at low speeds and enables smooth transition between control modes without fluctuation.
2Adaptability or versatility
If control mode is switched between vector control and constant current control, then adaptability to different speed ranges is improved, but rotation speed fluctuation occurs during switching
Solution Approach 1:
The system uses feedback by continuously monitoring the rotation phase and using it to generate the instructed phase during mode transitions. This feedback mechanism ensures that the phase information is synchronized between control modes, preventing rotation speed fluctuation and maintaining control stability during switching.
Solution Approach 2:
The system performs preliminary action by maintaining phase determination capability during constant current control mode, preparing the necessary phase information before switching to vector control. This ensures smooth transition without disruption to motor operation.
3Ease of operation
If constant current control is used at low speeds, then motor operation is simplified, but phase feedback control cannot be performed leading to larger phase difference
Solution Approach 1:
The system performs preliminary action by determining the rotation phase during constant current control mode, so that when switching to vector control, the phase information is already available. This maintains simplicity during constant current control while preparing for precise phase feedback control when needed.
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
Prevents motor control instability by ensuring accurate phase determination and smooth transitions between control modes, thereby minimizing rotation speed fluctuations and maintaining motor synchronism.
Implementation Method 1
U.S. Pat. No. 8,970,146 discusses a configuration in which the rotation phase of a rotor is determined based on an induced voltage generated in a winding wire of each phase of a motor by rotation of the rotor.
Data Source
AI summary
An apparatus to control a motor includes a detector that detects a driving current flowing through a motor winding, phase determiner that determines a motor rotor rotation phase based on the detected driving current, generator that generates an instructed phase, and controller. The controller includes a first mode where controlling the driving current flowing through the motor winding controls the motor based on a torque current component value such that a deviation between the generated instructed phase and the determined rotation phase is reduced, and a second mode in which a current of a predetermined magnitude controls the motor. The torque current component is expressed in a rotating coordinate system based on determined rotation phase. The generator generates, based on the rotation phase determined while executing second mode, the instructed phase in the first mode when a controlling driving current mode is switched from the second to the first mode.