Motor Control Circuit Noise Rejection via Position Prediction
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Solution Overview
Problem
Motor control systems for brushless motors face challenges in generating timely motor drive signals due to noise and chattering in sensor signals, leading to delayed signal processing and potential abnormal motor rotation, especially at high speeds.
Innovation Solution
A motor control circuit with a rotational position determining unit that stores the current rotational position and updates it based on subsequent sensor signals, generating motor control signals without being affected by chattering and noise, thereby reducing delay and ensuring smooth motor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a filter is used to remove noise and chattering from sensor signals, then the reliability of rotational position detection is improved, but the delay of the rotational position signal increases
Solution Approach 1:
The system performs preliminary action by predicting the rotational position based on previous valid positions and motor speed before actual signal processing occurs. This allows the control system to prepare motor drive signals in advance using predicted values, so when the filtered sensor signal becomes available, the processing can continue without significant delay. The prediction mechanism proactively compensates for the expected delay caused by filtering.
Solution Approach 2:
A rotational position prediction mechanism serves as an intermediary between the filtered sensor signal and the motor drive signal generation. This intermediary uses motor speed and previous rotational positions to generate predicted rotational positions that bridge the time gap created by filtering operations, allowing continuous control signal generation without waiting for filtered signals.
2Reliability
If a filter capable of removing large noise is used, then the reliability of motor control is improved, but the delay of the rotational position signal further increases, making it difficult to perform signal processing according to motor rotation
Solution Approach 1:
The system performs preliminary action by continuously calculating predicted rotational positions based on motor speed and previous positions before actual control decisions are made. This allows the control system to have ready-to-use position estimates that account for filtering delays, enabling timely motor drive signal generation even when using strong noise-rejection filters. The prediction computation proactively prepares control data in advance.
Solution Approach 2:
The rotational position prediction mechanism acts as an intermediary that decouples the relationship between heavy filtering and real-time control responsiveness. By introducing predicted rotational positions as an intermediate variable, the system can use aggressive filtering for reliability while maintaining signal processing speed through prediction-based control calculations.
3Loss of time
If no filter is used, then the delay of the rotational position signal is reduced, but large noise cannot be removed, causing abnormal current and motor rotation
Solution Approach 1:
The system performs preliminary validation by comparing predicted rotational positions with actual filtered positions in advance before generating motor drive signals. This preliminary check detects noise-induced anomalies early, allowing the system to prevent abnormal control actions before they occur. The prediction mechanism proactively identifies valid versus invalid sensor readings.
Solution Approach 2:
A feedback mechanism compares the predicted rotational position with the actual filtered rotational position to validate sensor readings. When discrepancies indicate noise contamination, the feedback loop prevents using corrupted data for motor control. This feedback-based validation ensures motor operation stability without requiring heavy filtering that would increase delay.
Data Source
AI summary
According to an embodiment, a motor control circuit includes a rotational position decoding unit, a rotational position determining unit, and a motor drive signal generating unit. The rotational position decoding unit is configured to generate a rotational position signal representing a rotational position of a motor according to a sensor signal provided by a sensor. The rotational position determining unit is configured to store a current rotational position of the motor based on the rotational position signal. When the rotational position signal represents a subsequent rotational position of the stored current rotational position, the rotational position determining unit is configured to update the stored current rotational position with the subsequent rotational position, and generate a motor control signal representing the subsequent rotational position. The motor drive signal generating unit is configured to generate a motor drive signal for driving the motor according to the motor control signal.