Fan Drive Circuit Current Control for Static Pressure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional fan driving systems face challenges in increasing maximum static pressure without excessive rotational speed at maximum air flow, leading to inefficient power consumption and torque reduction.
Innovation Solution
A driving system with a drive signal generating circuit, motor driving circuit, current detecting circuit, and drive signal changing circuit that restricts motor current increases when it exceeds a predetermined threshold, preventing excessive rotational speed during maximum air flow while allowing for adjustable settings to achieve desired static pressure and air flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the motor current is increased to enhance maximum static pressure, then the maximum static pressure is improved, but the rotational speed becomes excessive at maximum air flow condition
Solution Approach 1:
The patent applies dynamics by making the motor current dynamically adjustable based on operating conditions. The control device detects air flow amount and selectively changes motor current values: using a first (higher) current value when static pressure is high, and a second (lower) current value when air flow is high. This dynamic adjustment resolves the contradiction by allowing high current for maximum static pressure while preventing excessive speed at maximum air flow.
Solution Approach 2:
The patent employs parameter changes by varying the motor current parameter according to detected air flow conditions. The control device changes the motor current from a first value to a second value based on whether the air flow amount exceeds a threshold. This parameter adjustment enables optimization of both maximum static pressure and rotational speed characteristics without requiring physical modifications to the motor or fan structure.
2Power
If the motor current is increased to secure required rotational speed at maximum static pressure, then the torque is improved, but the power consumption increases excessively at maximum air flow
Solution Approach 1:
The control device dynamically adjusts motor current based on real-time detection of air flow amount. When air flow is low (high static pressure region), a higher current provides sufficient torque. When air flow is high (low static pressure region), a lower current prevents excessive power consumption. This dynamic control strategy resolves the torque-power consumption contradiction by adapting current to actual operating demands.
Solution Approach 2:
The patent changes the motor current parameter selectively based on operating conditions detected by the control device. By switching between a first current value (for torque requirement at high pressure) and a second current value (for power efficiency at high flow), the system optimizes the balance between torque output and power consumption without requiring oversized motor components.
3Stress or pressure
If the excitation windings are designed for high motor current at maximum static pressure, then the maximum static pressure is enhanced, but the rotational speed becomes excessive at maximum air flow
Solution Approach 1:
The patent applies dynamics by making motor current dynamically controllable through the control device that detects air flow amount and selectively switches between different current values. This allows the system to use higher current for enhancing maximum static pressure when needed, while automatically reducing current to prevent excessive rotational speed when air flow is high, without requiring physical redesign of the excitation windings.
Solution Approach 2:
The control device implements parameter changes by adjusting the motor current parameter based on detected air flow conditions. The system switches between a first current value (enabling enhanced maximum static pressure) and a second current value (preventing excessive speed at high air flow). This parameter control approach allows flexible optimization of static pressure characteristics without being constrained by fixed winding specifications.
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
This solution enables enhanced maximum static pressure without altering the maximum air flow, allowing for optimized settings of excitation windings and threshold adjustments to meet specific requirements, ensuring efficient power use and controlled motor current.
Implementation Method 1
a magnetic sensor H of a Hall element that detects magnetism of a plurality of permanent magnets provided in a rotor of the brushless motor
Implementation Method 2
The motor driving circuit MDC alternately brings a pair of the transistors SW1 and SW4 and a pair of the transistors SW2 and SW3 into conduction to cause an AC motor current to flow through excitation windings W in order to drive the brushless motor
Data Source
AI summary
A driving system for a fan that enables an increase in motor current that may be supplied to excitation windings at the time of a maximum static pressure without increasing the rotational speed excessively when an amount of maximum air flow is provided. The fan driving system includes a drive signal generating circuit that generates drive signals, a motor driving circuit that supplies a motor current to the motor in accordance with the drive signals, a current detecting circuit (resistance) that detects the motor current, and a drive signal changing circuit. The drive signal changing circuit changes the drive signals generated by the drive signal generating circuit to restrict an increase in the motor current when the motor current becomes larger than a threshold.