Motor Drive Device Abnormal Waveform Detection
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Solution Overview
Problem
Existing motor drive devices face challenges in accurately detecting rotation position and maintaining motor operation when a proper and improper waveform alternately appear in detection signals from rotation position sensors, especially with single sensors or when two out of three-phase output signals are abnormal.
Innovation Solution
A motor drive device that samples two detection signals, calculates the rotation position, and controls the voltage applied to the motor based on the square sum of these signals, applying a predetermined voltage when the square sum meets a specific value and a different voltage when it does not, to ensure continuous motor operation despite waveform alternations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the square sum method is used to detect abnormal waveforms, then measurement precision is improved, but the motor may stop unnecessarily when proper and improper waveforms alternately appear
Solution Approach 1:
The patent dynamically adjusts the determination threshold for abnormal waveform detection based on the motor's operation state. When the motor is rotating, a first determination threshold is used, while when the motor is stopped, a second determination threshold is applied. This dynamic threshold adjustment allows the system to tolerate waveform variations during rotation that would otherwise be detected as abnormalities, thereby preventing unnecessary motor stoppages while maintaining detection accuracy.
Solution Approach 2:
The patent changes the parameter of the determination threshold based on the motor's operation state (rotating vs. stopped). By switching between different threshold values according to the operational context, the system can accurately distinguish between genuine abnormalities and normal waveform variations caused by alternating proper and improper signals during motor rotation.
2Device complexity
If traditional amplitude matching is used for single sensor detection, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent transitions from single-dimension amplitude comparison to two-dimension square sum calculation. By computing the square sum of sine and cosine detection signals (which should equal 1 for normal waveforms), the system gains an additional dimension for abnormality detection. This mathematical transformation enables accurate detection of waveform abnormalities even with a single sensor, overcoming the limitation of traditional amplitude matching methods.
3Productivity
If voltage control based on square sum is implemented, then productivity is improved through continuous operation, but device complexity increases
Solution Approach 1:
The patent implements a self-service control mechanism where the voltage control system automatically adjusts output based on real-time square sum calculations from the detection signals. The controller autonomously determines whether to apply first voltage (normal operation) or second voltage (abnormal condition) without external intervention, enabling continuous motor operation while adapting to waveform variations. This self-adjusting mechanism maintains productivity while the complexity is managed through algorithmic control rather than additional hardware.
Data Source
AI summary
A motor drive device inputs two detection signals from a rotation position sensor thereby to detect a rotation position, and controls a voltage to be applied to a motor according to the detected rotation position. The motor drive device has a control unit for outputting a first voltage in a first state in which the square sum of sampling values sampled from the two detection signals is a predetermined value, and outputting a second voltage in a second state in which the square sum is not the predetermined value.