Blower Motor Braking Current Control
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Solution Overview
Problem
Blower apparatuses with electric drive motors experience overrun times of 3 to 5 seconds after shutdown, resulting in a persisting blower air flow that is disruptive when handling lightweight materials like leaves, as the rotational inertia of the blower wheel and motor cause continued air flow despite motor shutdown.
Innovation Solution
The blower apparatus incorporates a control unit that applies a braking current to the drive motor, controlling its rotational speed to achieve a characteristic curve with an even negative slope, effectively reducing the blower air flow to a non-effective residual volume quickly, allowing the user to turn the air flow on or off as needed, and limiting perceived torque during deceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the blower wheel is mounted with minimal friction to reduce drive losses, then energy efficiency is improved, but the overrun time increases to 3-5 seconds causing disruptive residual air flow
Solution Approach 1:
The control unit applies a braking current to the drive motor before the natural overrun period would complete, creating a counteracting force that actively opposes the rotational momentum. This preliminary anti-action reduces the overrun time from 3-5 seconds to under 1 second, eliminating disruptive residual air flow while maintaining the low-friction mounting for energy efficiency.
2Duration of action of moving object
If a braking current is applied to reduce overrun time, then the residual air flow is reduced quickly, but additional control complexity is introduced
Solution Approach 1:
The control unit performs multiple functions: it controls the drive motor during normal operation, applies braking current during shutdown, and manages the field windings through short-circuiting. By integrating these diverse functions into a single control unit, the patent minimizes additional complexity while achieving rapid overrun reduction.
Solution Approach 2:
The control unit dynamically changes the electrical parameters of the drive motor by switching between drive current and braking current modes. It also adjusts the field winding configuration through short-circuiting at different stages. These parameter changes enable rapid deceleration without requiring complex mechanical braking mechanisms.
3Speed
If the field windings are short-circuited to achieve quick standstill, then the braking effectiveness is improved, but high current peaks may occur
Solution Approach 1:
The control unit short-circuits the field windings at the appropriate moment during the braking process, before the rotor comes to complete rest. This preliminary action ensures that the electromagnetic braking force is applied when most needed, maximizing deceleration effectiveness while controlling current peaks through proper timing and resistance management.
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 a rapid cessation of the blower air flow, reducing disruption during use and ensuring the air flow is fully shut off before it becomes ineffective, with the braking current also being used to charge the battery and manage torque, enhancing user control and operational efficiency.
Implementation Method 1
the control unit supports the deceleration of the drive motor via a braking current (I) in order to reduce the blower air flow
Implementation Method 2
Because of the minimal friction and the inertia of the blower wheel and the masses rotating with the blower wheel such as the rotor of the drive motor, overrun times of 3 to 5 seconds occur despite a switching off of the motor
Data Source
AI summary
The invention relates to a blower apparatus (1) having a blower wheel (4) for generating a blower air flow (50). The blower wheel (4) is arranged in a housing (2), wherein the blower wheel is driven by an electric drive motor (8). A blower tube (6) via which the generated blower air flow (50) is guided connects at an outlet (5). A control unit (17) is provided for controlling the rotational speed of the electric drive motor. For a quick reduction of the blower air flow (50), it is provided that the control unit (17) supports the deceleration of the drive motor (8) through a braking current (I).