Motor Controller Phase Switching Noise Reduction
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Solution Overview
Problem
Existing motor controllers fail to effectively reduce mechanical noise caused by current flowing through motor coils due to manufacturing tolerances in asymmetrical pole regions during phase switching.
Innovation Solution
A motor controller comprising a switch circuit, control unit, phase detecting unit, and current detecting unit, which sets a time point to detect driving current proportionally before phase switching based on manufacturing tolerance, allowing for early reduction of driving current to minimize noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If phase switching is performed based on ideal symmetrical pole regions, then the control logic is simple, but manufacturing tolerances cause asymmetrical pole regions leading to current flow and mechanical noise
Solution Approach 1:
The patent applies preliminary action by detecting the driving current at a specific time point before phase switching occurs. The control unit is configured to detect current at time point Td1, which is calculated as Td1 = (T1 - Td2) where Td2 represents the tolerance range. This advance detection allows the system to identify current flow caused by asymmetrical pole regions before the phase switching happens, enabling corrective action to be taken in advance to prevent mechanical noise.
2Measurement precision
If current detection is performed at the exact phase switching moment, then the detection timing is precise, but it is too late to prevent current flow and noise generation
Solution Approach 1:
The patent shifts the detection timing from the exact phase switching moment to a preliminary time point Td1 before switching occurs. This time point is precisely calculated based on the relationship Td1 = (T1 - Td2), where T1 is the period and Td2 is the tolerance. By detecting current at this preliminary time point, the system maintains measurement precision while enabling preventive control action to stop current flow before it causes noise.
Solution Approach 2:
The patent implements feedback by using the current detection result at time point Td1 to control the switching timing. The control unit detects the driving current and uses this feedback information to adjust the phase switching timing, thereby preventing current flow and mechanical noise. This closed-loop feedback mechanism ensures that the system adapts to the actual pole region asymmetry.
3Power
If the driving current is not reduced before phase switching, then the motor operates with full power, but current remains flowing causing mechanical noise
Solution Approach 1:
The patent applies preliminary action by reducing the driving current before phase switching occurs. The control unit detects current at time point Td1 and implements current reduction control in advance, ensuring that when phase switching happens, the current flow is already minimized or stopped. This prevents mechanical noise while maintaining full power operation during the actual motor drive periods.
Solution Approach 2:
The patent applies preliminary anti-action by taking countermeasures before the harmful effect occurs. Specifically, the system detects current at time point Td1 and implements control to prevent current flow before phase switching, thereby preemptively counteracting the condition that would cause mechanical noise. This ensures full power operation during normal motor drive while eliminating noise during switching transitions.
Data Source
AI summary
A motor controller is configured to reduce the motor noise. The motor controller is used for driving a motor, where the motor has a motor coil and a rotor. The rotor is divided into four pole regions N1, S1, N2, and S2 to switch phases. The four pole regions have a manufacturing tolerance and the pole region N1 has a time interval T1. The motor controller comprises a switch circuit, a control unit, a phase detecting unit, and a current detecting unit. The switch circuit is configured to supply a driving current to the motor coil. Based on the manufacturing tolerance and the time interval T1, the time point to detect the driving current is set to be a proportional time PT before the phase switching, where PT/T1 is greater than the manufacturing tolerance.