Impact Rotation Tool PWM Frequency Switching
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Solution Overview
Problem
Conventional impact rotation tools generate excessive heat and audible oscillation noise due to PWM control, which are undesirable for user comfort and tool performance.
Innovation Solution
An impact rotation tool with a controller that dynamically switches the PWM control frequency based on detected impact conditions, using a higher frequency when no impact is generated to reduce noise and a lower frequency when impact is detected to minimize heat and noise disturbance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the PWM frequency is increased to reduce audible oscillation noise, then the noise disturbance is decreased, but the heat generated by the switching elements increases
Solution Approach 1:
The patent applies dynamics by making the PWM control frequency adjustable and switchable between different ranges (first frequency range and second frequency range) based on operational conditions. The control frequency is not fixed but can be dynamically changed according to whether an impact state is detected, allowing the system to adapt to different operating scenarios and resolve the contradiction between noise reduction and heat generation.
Solution Approach 2:
The patent changes the parameter of PWM control frequency between two distinct ranges. By switching between a first frequency range (lower frequency) and a second frequency range (higher frequency), the system can optimize performance for different conditions: using lower frequency to reduce heat during impact operations and higher frequency to reduce audible noise during non-impact operations.
2Temperature
If the PWM frequency is decreased to reduce heat generation, then the heat in switching elements is reduced, but the audible oscillation noise increases
Solution Approach 1:
The system dynamically adjusts the PWM frequency based on detected impact conditions. When no impact is detected, the system switches to a higher frequency range to minimize audible noise. When impact is detected, it switches to a lower frequency range to reduce heat generation, thereby dynamically resolving the contradiction between these two harmful effects.
Solution Approach 2:
The patent utilizes parameter changes by switching the PWM control frequency between a first frequency range and a second frequency range based on operational state. This parameter adjustment allows the system to optimize for either heat reduction or noise reduction depending on the current operating conditions, specifically whether an impact state is present.
3Device complexity
If a fixed PWM frequency is used, then the control system is simple, but it cannot simultaneously reduce both heat generation and audible noise
Solution Approach 1:
The patent introduces dynamic frequency switching capability that responds to impact detection. The control system includes an impact detector and a frequency switch unit that automatically adjusts the PWM frequency based on detected conditions. This dynamic approach allows the system to reduce both heat and noise by adapting the frequency to operational needs, justifying the increased complexity through improved performance.
Solution Approach 2:
The system employs parameter changes by switching between two distinct PWM frequency ranges based on impact detection results. The control frequency is changed from a first frequency range to a second frequency range (or vice versa) according to whether an impact state is detected, enabling the system to simultaneously address both heat generation and audible noise issues that cannot be resolved with a fixed frequency.
Data Source
Figure 1~2
Figure 3
AI summary
An impact rotation tool (11) includes a motor (15), a switching element (Q) that performs a switching operation based on a PWM control signal (CS), and a controller (40) that performs PWM control on the motor with the switching operation of the switching element (Q). The controller (40) includes a PWM control unit (41) that generates the PWM control signal (CS), an impact detector (42) that detects whether or not an impact has been generated, and a control frequency switch unit (43) that selects a control frequency of the PWM control signal (CS1 CS2) from a first control frequency (fr1), which is in an audible range, and a second control frequency (fr2), which is higher than the frequency in the audible range. The controller (40) outputs a PWM control signal (CS2) having the second frequency (fr2) when detecting that an impact has not been generated (A1) and outputs a PWM control signal (CS1) having the first frequency (fr1) when detecting that an impact has been generated (A2).