Motor Controller Phase Switching Noise Reduction
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Solution Overview
Problem
Conventional sensorless driving methods for three-phase motors generate noise and vibration due to discontinuous phase currents during back electromotive force detection, and Hall sensors are prone to environmental interference, increasing system volume and cost.
Innovation Solution
A motor controller with a switch circuit, driving circuit, and pulse width modulation circuit that adjusts the duty cycle to control the speed of a three-phase motor by varying the number of floating phase time intervals for phase switching, reducing noise and vibration by optimizing phase current modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the motor controller detects the back electromotive force during the floating phase time interval for phase switching, then the phase switching can be achieved, but discontinuous phase current is generated resulting in noise and vibration
Solution Approach 1:
The patent applies dynamics by making the number of floating phase time intervals variable rather than fixed. The controller dynamically adjusts the number of floating phase time intervals based on the motor's operational state (start state vs. stable state), allowing the system to optimize between phase switching reliability and noise reduction in different operating conditions
Solution Approach 2:
The patent changes the parameter of floating phase time intervals from a constant value to a variable value. By adjusting the number of floating phase time intervals according to operational state, the system modifies this key parameter to resolve the contradiction between ensuring reliable phase switching and minimizing discontinuous phase current that causes noise and vibration
2Reliability
If more floating phase time intervals are used for phase switching, then the success rate of phase switching increases, but the noise and vibration of the motor increases
Solution Approach 1:
The system dynamically adjusts the number of floating phase time intervals based on operational state. During start state, more intervals (N1) are used to ensure reliable phase switching, while during stable state, fewer intervals (N2) are used to reduce noise and vibration, with N1 > N2
Solution Approach 2:
The patent implements periodic adjustment of the floating phase time intervals based on the motor's operational phase. The controller periodically transitions between using N1 intervals (during start state) and N2 intervals (during stable state), creating a rhythmic adaptation to operational conditions that balances reliability and noise reduction
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 effectively reduces noise and vibration in three-phase motors by dynamically adjusting the number of floating phase time intervals based on the motor's operational state, enhancing phase switching success rates and stability.
Implementation Method 1
The pulse width modulation circuit generates a pulse width modulation signal to the driving circuit, where the pulse width modulation signal has a duty cycle. The motor controller may control the speed of the three-phase motor by adjusting the duty cycle.
Implementation Method 2
In the sensorless driving method, the motor controller detects the back electromotive force of the floating phase for switching phases, so as to drive the three-phase motor.
Data Source
AI summary
A motor controller comprises a switch circuit, a driving circuit, and a pulse width modulation circuit. The switch circuit is coupled to a three-phase motor for driving the three-phase motor. The driving circuit generates a plurality of control signals to control the switch circuit. When the three-phase motor is operated in a start state, the motor controller may enable an electric period to be divided into more floating phase time intervals for switching phases, so as to increase the success rate of phase switching. When the three-phase motor is operated in a stable state, the motor controller may enable the electric period to be divided into less floating phase time intervals for switching phases, so as to reduce the noise and vibration of the three-phase motor.