Impact Tool Motor Control Using d-q Current Impact Detection
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Solution Overview
Problem
Existing electric power tools lack an effective means to determine whether the impact mechanism is performing an impact operation, leading to inefficiencies in control and performance.
Innovation Solution
An electric power tool incorporating an impact detecting unit that measures d-axis and q-axis currents to determine if an impact operation is occurring, allowing for precise control gain adjustments in the control unit to optimize motor performance during impact operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the electric motor is controlled with constant duty ratio control from start until impact detection, then the motor can be driven with simple control, but the control precision and motor performance during impact operations cannot be optimized
Solution Approach 1:
The control method transitions from static constant duty ratio control to dynamic control that adapts based on operational state. The controller switches between constant duty ratio control (during startup and non-impact phases) and constant rotation speed control (during impact operations), optimizing motor performance for each specific operational condition.
Solution Approach 2:
The system uses impact detection feedback to determine when to switch control modes. By detecting impact conditions and using this information to adjust the control strategy, the system achieves precise control during impact operations while maintaining simple control during other phases.
2Device complexity
If the controller executes constant duty ratio control from start until impact detection, then the control system remains simple, but the motor performance during impact operations cannot be optimized
Solution Approach 1:
The control system dynamically adjusts its strategy based on detected impact conditions. During non-impact phases, simple constant duty ratio control is used. Upon detecting impact operations, the system transitions to constant rotation speed control, optimizing motor performance specifically for impact tasks without permanently increasing system complexity.
Solution Approach 2:
The control method changes operational parameters based on impact detection. The controller monitors impact conditions and adjusts motor control parameters accordingly, switching between duty ratio control and rotation speed control to optimize performance for different operational states.
3Device complexity
If no impact detection mechanism is used, then the device structure remains simple, but the ability to determine whether impact operation is occurring is lost
Solution Approach 1:
The system replaces complex mechanical impact detection mechanisms with electrical sensing methods. By measuring electrical parameters such as current, voltage, or power consumption that change during impact operations, the system achieves impact detection without adding significant mechanical complexity to the device structure.
Solution Approach 2:
The control unit acts as an intermediary that processes electrical signals to detect impact conditions. Rather than directly sensing mechanical impact, the system uses electrical parameter changes as intermediaries to infer impact operation status, maintaining structural simplicity while gaining detection capability.
Data Source
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AI summary
An object of the present disclosure is to provide an electric power tool including a novel means for determining whether or not an impact mechanism is performing any impact operation. An electric power tool (1) includes an electric motor (AC motor 15), an impact mechanism, an impact detecting unit (49), and a measuring unit (60). The impact mechanism performs an impact operation that generates impacting force by receiving motive power from the electric motor. The impact detecting unit (49) determines whether or not the impact operation is being performed. The measuring unit (60) measures at least one of a d-axis current or a q-axis current, each of which is supplied to the electric motor. The impact detecting unit (49) determines, based on at least one of a measured value (current measured value id1) of the d-axis current or a measured value (current measured value iq1) of the q-axis current, whether or not the impact operation is being performed. The measured values (current measured values id1, iq1) of the d-axis current and the q-axis current have been obtained by the measuring unit (60).