Fan Motor Control Device with Power Factor Correction
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Solution Overview
Problem
Conventional brushless DC motor systems face challenges in reducing harmonics and reactive power, and solely relying on pulse-width modulation signals for speed control increases noise and consumption in electronic elements.
Innovation Solution
A motor control device with a power factor correction circuit that converts alternating current to direct current, includes a step-up unit, voltage detecting units, and a motor controlling circuit to generate driving signals based on voltage differences, allowing for regulable voltage levels and reduced noise and consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a power factor correction circuit is used to reduce harmonics and reactive power, then the quality of power source is improved, but the device complexity increases
Solution Approach 1:
The patent combines the power factor correction function and motor control function into a single integrated circuit. The power factor correction circuit includes a converting circuit, step-up unit, and voltage detecting units, while the motor control circuit receives voltage reference signals from these detecting units and generates driving signals accordingly. This integration reduces the number of separate components and simplifies the overall system structure while maintaining power quality improvement.
Solution Approach 2:
The power factor correction circuit serves multiple functions: it corrects power factor by reducing harmonics and reactive power, provides regulable voltage levels for motor speed control, and supplies voltage reference signals for motor control. This multi-functionality eliminates the need for separate power quality improvement devices and motor controllers, thereby reducing device complexity while achieving both power source quality improvement and motor control.
2Speed
If motor speed is controlled solely by pulse width modulation signal, then the rotational speed can be regulated, but the noise and consumption of electronic elements increase
Solution Approach 1:
The patent changes the control parameter from solely PWM duty cycle to a combination of voltage level (via step-up unit) and PWM signal. The step-up unit generates a regulable second voltage based on the first voltage from the converting circuit, and the motor control circuit uses both this voltage level and PWM modulation to control motor speed. This dual-parameter control reduces the switching frequency and amplitude of electronic elements, thereby decreasing noise and power consumption while maintaining speed regulation capability.
3Reliability
If power factor correction circuit operates during motor idling or light load, then power quality is maintained, but the consumption of power factor correction circuit increases
Solution Approach 1:
The patent implements dynamic operation of the power factor correction circuit based on motor load conditions. The motor control circuit determines whether the motor is in idle or light load state and dynamically adjusts the operation mode: during idle/light load, it uses primarily PWM control with minimal power factor correction activity; during heavy load, it activates full power factor correction functionality. This dynamic adaptation reduces the consumption of the power factor correction circuit during low-demand periods while maintaining power quality when needed.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces harmonics and reactive power, decreases noise and consumption in electronic elements, and optimizes motor speed control by using a regulable voltage level, while also reducing power factor correction circuit consumption during idling or light loads.
Implementation Method 1
The converting circuit receives a voltage of the alternating current power source and converts the voltage of the alternating current power source to be a voltage of direct current
Implementation Method 2
The step-up unit is electrically connected with the converting circuit for receiving the first voltage and generating a second voltage according to the first voltage
Data Source
AI summary
A fan includes a motor control device which is electrically connected with a motor and an alternating current power source. The motor control device includes a converting circuit, a power factor correction circuit and a motor controlling circuit. The voltage of the alternating current power source is converted to be direct current voltage by the converting circuit and the power factor correction circuit, and then the direct current voltage is outputted to the motor control circuit. The motor controlling circuit generates a driving signal in accordance with the direct current voltage for driving the motor to operate.