Radial Fan Speed Control for Ventilation Noise Reduction
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Solution Overview
Problem
Ventilation devices with radial fans operated in constant mode produce excessive noise due to increased speed at low volume flows, leading to an unfavorable user experience, especially when system resistance is high or design points are incorrect.
Innovation Solution
The method involves changing the fan characteristic to reduce the limit pressure difference at minimum volume flow, keeping the speed constant or reducing it as volume flow decreases, and using pulse width modulation to regulate the radial fan's speed, thereby reducing noise and maintaining a constant or almost constant volume flow up to an intermediate pressure difference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the radial fan is operated in constant mode with constant operating parameters, then the volume flow is maintained, but the noise increases due to excessive speed at low volume flows
Solution Approach 1:
The patent applies dynamics by transitioning from constant-speed operation to variable-speed operation of the radial fan. The control device dynamically adjusts the rotational speed of the radial fan based on the pressure difference detected by the differential pressure sensor, allowing the fan to operate at optimal speeds for different flow conditions rather than maintaining a fixed high speed that generates excessive noise at low volume flows.
Solution Approach 2:
The patent changes the operational parameters of the radial fan by adjusting its rotational speed according to the pressure difference. The control device modifies the speed parameter of the fan motor based on real-time pressure measurements, enabling the system to maintain volume flow while reducing noise by operating at lower speeds when pressure difference is high and volume flow is low.
2Productivity
If the speed of the radial fan is increased to maintain volume flow, then the volume flow is sustained, but the pressure difference increases leading to higher energy consumption
Solution Approach 1:
The patent implements feedback control by using a differential pressure sensor to continuously monitor the pressure difference across the radial fan and feeding this information back to the control device. The control device then adjusts the fan speed based on this feedback, reducing energy consumption by lowering the speed when high pressure difference indicates sufficient flow, and only increasing speed when necessary to maintain volume flow.
3Productivity
If the radial fan operates at high speed to overcome high system resistance, then the volume flow is maintained, but the noise generation increases
Solution Approach 1:
The patent applies dynamics by making the radial fan speed adaptive rather than fixed. The control device continuously adjusts the fan speed based on real-time pressure difference measurements, allowing the system to dynamically respond to varying system resistance conditions and maintain volume flow without consistently operating at high noise-generating speeds.
Solution Approach 2:
The patent changes the speed parameter of the radial fan based on the pressure difference caused by system resistance. When system resistance is high, the control device adjusts the fan speed appropriately to maintain volume flow while minimizing noise, rather than maintaining a constantly high speed that would generate excessive noise regardless of actual flow needs.
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 approach reduces noise levels by limiting the pressure difference and maintaining a stable volume flow, preventing excessive noise generation at low volume flows, and allowing for flexible operation modes that balance performance and comfort.
Implementation Method 1
an electronically commutated electric motor for driving the radial fan impeller
Implementation Method 2
a radial fan for conveying air, which has a radial fan impeller
Implementation Method 3
a duty cycle is determined and set on the radial fan, or used to control it. The electric motor of the radial fan is an electronically commutated motor. Such a motor is also known as a brushless DC motor or EC motor. When the radial fan is controlled using PWM, constant operation is preferably achieved at a constant duty cycle, for example, at the maximum duty cycle, i.e., in particular, a duty cycle of 100%
Data Source
AI summary
The invention relates to a method for operating a ventilation device, wherein the ventilation device has a radial fan for conveying air, which has a radial fan impeller and an electronically commutated electric motor for driving the radial fan impeller and has a fan characteristic curve (1,2,3,4,5,) according to which the radial fan causes a certain pressure difference (Δp) across the radial fan at a certain volume flow rate (V) conveyed by the radial fan, wherein, in constant operation of the radial fan with at least one constant operating parameter, a maximum pressure difference (Δpmax) results at a minimum volume flow rate and a maximum volume flow rate (Vmax) results at a minimum pressure difference.The invention provides that the radial fan is operated in at least one operating mode such that the limiting pressure difference present at minimum volume flow is smaller than the maximum pressure difference (Δpmax). The invention further relates to a ventilation unit.