Sensorless Spindle Motor Phase Control via Demagnetization Timing
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Solution Overview
Problem
Conventional spindle motor driving systems require position sensors to accurately control the spindle motor, which increases costs and can fail to generate modulation signals without them, leading to inaccurate phase control.
Innovation Solution
A sensorless spindle motor driving system that uses a motor controller to generate modulation signals and floating phases, with a demagnetization measuring circuit to calculate demagnetization time based on terminal voltage changes, allowing for phase detection without position sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a position sensor is used to control the spindle motor, then the phase control accuracy is improved, but the system cost increases
Solution Approach 1:
The patent extracts the position sensing function from a dedicated position sensor and implements it within the motor controller using existing processing units. This eliminates the need for separate position sensors while maintaining phase control accuracy through software-based position detection algorithms.
Solution Approach 2:
The motor controller is designed to perform multiple functions: it controls motor switching, processes current feedback, and executes position detection algorithms. By making the motor controller multi-functional, the patent eliminates the need for separate position sensing hardware, reducing system cost while maintaining control precision.
2Measurement precision
If a position sensor is used to control the spindle motor, then the phase control accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent merges the position detection functionality into the motor controller unit. The same processor that controls motor switching also performs position detection by analyzing current waveforms and calculating rotor position, thereby reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The motor controller uses its own internal resources (processor, current sensing circuits) to perform position detection without requiring external position sensors. The system serves its own positioning needs through software-based algorithms that calculate rotor position from electrical parameters.
3Ease of operation
If the floating phase is not adjusted, then the control simplicity is maintained, but the demagnetization time increases and noise increases
Solution Approach 1:
The patent implements dynamic adjustment of the floating phase based on real-time motor operating conditions. The motor controller continuously monitors current waveforms and adjusts the floating phase duration and timing to optimize demagnetization, thereby reducing demagnetization time and noise while maintaining control simplicity through automated adaptation.
Solution Approach 2:
The system uses feedback from current sensing circuits to detect motor position and load conditions. Based on this feedback, the motor controller automatically adjusts the floating phase parameters to achieve optimal demagnetization performance, reducing both demagnetization time and noise without requiring manual intervention.
Data Source
AI summary
A driving method for a spindle motor and associated driving system and apparatus are provided. The driving method includes the following steps. Plural modulation signals and plural floating phases corresponding to the plural modulation signals are adjusted. A floating period comes immediately after an active period of each of the plural modulation signals according to the plural floating phases. During the floating period, a demagnetization time of the spindle motor is acquired according to a first terminal voltage signal at a first terminal of the spindle motor. If the demagnetization time is not smaller than the threshold time period, the step of adjusting the plural modulation signals is repeatedly done. Whereas, if the demagnetization time is smaller than the threshold time period, after the demagnetization time, a phase of the spindle motor is obtained according to the first terminal voltage signal.