Sensorless Motor Controller Phase Switching for Startup
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Solution Overview
Problem
Conventional motor controllers using Hall sensors are prone to reduced accuracy due to environmental influences and increased system volume and cost, necessitating a sensorless driving method that effectively detects phase switching time points during motor startup.
Innovation Solution
A motor controller comprising a switch circuit, control unit, detecting unit, and counting unit that determines phases based on rotation direction and switches between phases (second, third, or fourth) when the phase switching time point cannot be detected within a starting time, with adjustable starting time settings to enhance startup success rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Hall sensor is used for switching phases, then phase switching accuracy is improved, but system volume and cost increase
Solution Approach 1:
The patent extracts and eliminates the Hall sensor from the motor control system, replacing it with a sensorless driving method that uses the motor's own back electromotive force for phase detection, thereby reducing system volume and cost while maintaining functional capability
Solution Approach 2:
The motor controller uses the motor's own back electromotive force to detect phase switching time points, making the motor self-diagnostic without requiring external sensors, which reduces system complexity and cost
2Device complexity
If sensorless driving method is used, then system volume and cost are reduced, but phase switching detection reliability decreases during startup
Solution Approach 1:
The patent implements a preliminary commutation mechanism that activates during the startup phase when back electromotive force detection is unreliable, ensuring the motor starts successfully before transitioning to normal sensorless control
Solution Approach 2:
The patent dynamically switches between different control modes: using back electromotive force detection during normal operation and switching to commutation mechanism during startup, optimizing reliability across different operating conditions
3Ease of operation
If fixed starting time is used, then control simplicity is maintained, but startup success rate under varying loads is reduced
Solution Approach 1:
The patent makes the starting time dynamic by adjusting it according to load conditions (light load, heavy load, reverse rotation), allowing the system to adapt to varying operating conditions while maintaining a relatively simple control structure
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 motor controller increases the success rate of motor startup by efficiently switching phases and adapting to varying load conditions and rotation states, improving reliability and reducing system complexity and cost.
Implementation Method 1
the motor controller may switch phases by detecting the back electromotive force of the floating phase
Data Source
AI summary
A motor controller comprises a switch circuit and a control unit. The switch circuit is coupled to a motor for driving the motor. The control unit is configured to generate a plurality of control signals to control the switch circuit. The motor controller sequentially determines a first phase, a second phase, a third phase, and a fourth phase based on a rotation direction. When the motor controller is in the first phase and the motor controller is unable to detect a phase switching time point within a starting time, the motor controller switches from the first phase to the second phase, the third phase, or the fourth phase. The motor controller is configured to increase a success rate of starting the motor.