Motor Control Device Using Variable Duty Cycle PWM
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Solution Overview
Problem
Conventional motor control devices generate loud noise and current pulses due to fixed duty cycles during phase changes, limiting their applicability, especially in fan motors.
Innovation Solution
A motor control method utilizing a programmable IC that adjusts the duty cycle of the PWM signal to a minimum when the phase signal changes, reducing input power and minimizing noise and current pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed duty cycle is used in conventional motor control devices, then the motor can operate with simple control circuitry, but loud noise and current pulses occur during phase changes
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed duty cycle to a variable duty cycle that changes based on motor operating conditions. The control device dynamically adjusts the duty cycle of PWM signals during phase changes to minimize noise and current pulses, making the control parameter adaptive rather than static.
Solution Approach 2:
The patent implements parameter changes by modifying the duty cycle parameter of the PWM signal. During phase changes, the duty cycle is adjusted to specific values (e.g., 0% or 100%) to reduce harmful effects, while during normal operation it is set to maintain motor speed, thereby optimizing performance across different operating states.
2Object-generated harmful factors
If the duty cycle is adjusted to minimize input power during phase changes, then noise and current pulses are reduced, but the control system becomes more complex
Solution Approach 1:
The patent employs feedback by using Hall elements to detect the motor's phase position and rotational speed, then feeding this information back to the control device. This feedback mechanism enables the control device to automatically adjust the duty cycle based on real-time motor state, reducing noise during phase changes without requiring complex external control systems.
Solution Approach 2:
The control device performs self-service by autonomously determining when phase changes occur based on feedback from Hall elements and automatically adjusting the duty cycle accordingly. This self-regulating capability reduces noise and current pulses without requiring additional complex control circuitry or external intervention.
3Stability of the object's composition
If conventional PWM control is used with fixed duty cycle, then the motor maintains rotation, but applicability is limited particularly for fan motors due to noise
Solution Approach 1:
The patent applies dynamics by making the duty cycle adaptive rather than fixed. The control device dynamically adjusts the duty cycle based on motor operating conditions, particularly during phase changes, enabling the system to maintain motor rotation stability while adapting to different application requirements such as fan motors where noise reduction is critical.
Solution Approach 2:
The patent implements universality by creating a control system that can effectively handle multiple motor types and applications. By using variable duty cycle control with feedback from Hall elements, the system achieves both stable motor rotation and reduced noise, making it applicable to fan motors and other applications where conventional fixed duty cycle control is limited.
Data Source
AI summary
A motor control method and device. The motor control device includes a programmable integrated circuit (IC) receiving a phase signal, the phase of which is consistent with the rotation phase of a coil of the motor. The programmable IC generates a duty-cycle signal in accordance with the period of the phase signal. The duty-cycle signal comprises a rising segment and a falling segment and when the phase signal changes phase, the duty cycle represented by the duty-cycle signal is a first duty cycle, allowing the input power of the motor remain at a minimum. The duty-cycle signal is input to the coil, controlling the coil on and off and, thereby rotating the motor.