Electric Fan Motor Speed Control During Voltage Fluctuations
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Solution Overview
Problem
Existing speed control methods for electric fan drives in motor vehicles result in noise and inefficiency due to speed oscillations caused by fluctuations in the vehicle's electrical system voltage, leading to overdesign and increased costs of the drive motor.
Innovation Solution
A method and device that regulate the motor speed of an electric fan drive by setting a lower speed setpoint during voltage and load fluctuations, with time-limited speed control and adaptive adjustment based on the current flap position and load profile, using a controller and semiconductor switches to minimize noise and maintain maximum air flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the motor speed is regulated to a high setpoint to maintain maximum air flow, then the air flow performance is improved, but speed oscillations and noise increase due to electrical system voltage fluctuations
Solution Approach 1:
The patent applies dynamics by making the speed setpoint adjustable and adaptive rather than fixed. The control device dynamically modifies the speed setpoint based on detected voltage fluctuations, lowering it during instability to prevent noise while maintaining it at maximum during stable operation to ensure air flow performance.
Solution Approach 2:
The patent changes the parameter of speed setpoint based on the electrical system's operating conditions. By detecting voltage fluctuations and adjusting the speed setpoint accordingly (lowering during fluctuations, maintaining at maximum during stability), the system resolves the contradiction between air flow performance and noise reduction.
2Reliability
If the motor is over-designed with high power reserves to handle voltage fluctuations, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent implements feedback by having the control device continuously detect the electrical system voltage and use this information to adjust the speed setpoint. This closed-loop feedback mechanism allows the system to respond to voltage fluctuations in real-time, ensuring reliable operation without requiring an over-designed motor with excessive power reserves.
Solution Approach 2:
The control device performs self-adjustment by automatically modifying the speed setpoint based on detected voltage conditions. This self-service capability eliminates the need for complex mechanical overload protection or excessively sized motor components, achieving reliability through intelligent control rather than hardware redundancy.
3Stability of the object's composition
If the PWM duty cycle is increased to maintain motor speed during voltage drops, then speed stability is improved, but motor overload and component stress increase
Solution Approach 1:
The patent applies preliminary action by proactively lowering the speed setpoint when voltage fluctuations are detected, before the motor can be overloaded. This preventive approach avoids the need to increase PWM duty cycle to excessive levels, thereby maintaining speed stability while protecting components from stress and overload damage.
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 allows the fan to operate at nearly 100% power under all conditions with reduced noise and acoustic impairments, preventing the need for an over-designed motor, thus ensuring efficient and cost-effective operation.
Implementation Method 1
The known control or regulation methods are essentially based on a change in the duty cycle of semiconductor switches controlled by means of pulse width modulation (PWM) in the load circuit of the electric motor
Implementation Method 2
a method for operating an electromotive fan drive (fan) of a motor vehicle, in particular a control method for controlling the speed of a brushless electric motor
Data Source
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AI summary
The invention relates to a method and a device for operating a closed-loop or open-loop speed-controlled electric motor (EM) of a fan drive, which motor is connected to an on-board system voltage (UB) of a motor vehicle and the motor speed (n) of which is set to a defined first desired speed (nsoll), wherein, if the on-board system voltage (UB) fluctuates, the motor speed (n) is set to a desired speed (n*soll) which is low compared with the first desired speed (nsoll).