Motor Control Apparatus Using Dual Threshold Duty Ratio Computation
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Solution Overview
Problem
Existing motor control apparatuses face challenges in accurately controlling electric motors due to external disturbances like radio wave radiation, leading to inaccurate duty ratio computation and prolonged inspection times, especially when using methods like harnesses with shield structures or ferrite beads, which increase costs.
Innovation Solution
A motor control apparatus and method that utilize multiple threshold values to determine and generate control signals for electric motors, allowing for accurate control even in disturbed conditions without the need for costly shielding or ferrite beads, by comparing drive command signal levels with a plurality of threshold values to compute appropriate duty ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single threshold value is used for duty ratio computation, then the computation is simple, but the control accuracy deteriorates under external disturbances like radio wave radiation
Solution Approach 1:
The single threshold value is segmented into multiple threshold values (first threshold value and second threshold value). The first threshold value is used for normal operation, while the second threshold value is used when external disturbances are detected. This segmentation allows the system to maintain simple computation under normal conditions while improving accuracy under disturbed conditions by switching between different threshold values.
Solution Approach 2:
The threshold value structure is made dynamic by introducing a determination circuit that switches between the first and second threshold values based on the detection of external disturbances. The system dynamically selects the appropriate threshold value according to the operational conditions, thereby maintaining high computation accuracy across varying environments without requiring a fixed complex structure.
2Reliability
If costly shielding structures or ferrite beads are used to mitigate interference, then the anti-interference capability is improved, but the manufacturing cost increases
Solution Approach 1:
Instead of using physical shielding structures or ferrite beads, the invention changes the electrical parameter (threshold value) to mitigate interference. By switching between different threshold values based on disturbance detection, the system achieves anti-interference capability through parameter adaptation rather than physical protection, thereby avoiding increased manufacturing costs.
Solution Approach 2:
The invention replaces the mechanical/physical approach (shielding structures, ferrite beads) with an electrical/control approach (multiple threshold values and determination circuit). This substitution eliminates the need for additional physical components while achieving the same anti-interference effect, thereby reducing manufacturing complexity and cost.
3Productivity
If the transistor is not completely turned off due to external voltage application, then the system remains operational, but the duty ratio computation becomes inaccurate
Solution Approach 1:
The determination circuit provides feedback about the operational state by detecting external disturbances. When a disturbance is detected (indicating the transistor may not be completely off), the system switches to using the second threshold value for duty ratio computation. This feedback mechanism allows the system to maintain operability while compensating for the inaccuracy introduced by the disturbed state.
Data Source
AI summary
A first duty ratio of a drive command signal is computed by comparing a level of the drive command signal with a first threshold value at a motor controller of a blower motor apparatus. A second duty ratio of the drive command signal is computed by comparing the level of the drive command signal with a second threshold value at the motor controller. A control signal is generated based on the first duty ratio and the second duty ratio in the motor controller and is used to drive a blower motor of the blower motor apparatus.