AC Voltage Measurement Offset Compensation in Handheld Power Tools
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Solution Overview
Problem
Existing measuring systems for AC voltage in hand-held power tools face challenges in accurately determining the effective value of AC voltage due to fluctuations and variations in power supply, particularly when reference potentials are decoupled from AC voltage potentials, leading to measurement offsets.
Innovation Solution
A measuring system utilizing a regulated DC voltage source with a voltage divider and a voltmeter connected to a tap between the power supply and ground, where the resistance values are selected to ensure the average voltage at the tap is at the midpoint of the measurement range, allowing for decoupled potentials to be compensated and optimizing the measurement range of the voltmeter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a voltmeter is designed as an electric component operated by direct voltage with decoupled reference potentials, then the voltmeter can be integrated into the additional circuits of the hand-held power tool, but measurement offsets occur due to decoupled ground potentials from AC voltage potentials
Solution Approach 1:
The patent creates an equipotential relationship between the decoupled ground reference and the AC voltage reference by introducing a regulated DC voltage source that references its ground to the neutral conductor. This ensures both the voltmeter and AC voltage measurements share a common reference potential, eliminating measurement offsets while maintaining circuit integration
2Measurement precision
If the measurement range of the voltmeter is optimized for standard AC voltages, then accurate measurements are achieved under normal conditions, but measurement accuracy deteriorates when AC voltage fluctuations occur due to different national electric power supplies
Solution Approach 1:
The patent implements a dynamic adaptation mechanism where the regulated DC voltage source continuously adjusts its output voltage in response to fluctuations in the AC voltage magnitude. This dynamic regulation ensures the voltmeter operates within its optimal measurement range regardless of the specific power supply standard or voltage fluctuations, enabling accurate measurements across different national electric power supplies
Solution Approach 2:
The patent changes the operating parameters of the measurement system by using a regulated DC voltage source that dynamically adjusts its output voltage level based on the detected AC voltage magnitude. This parameter adjustment allows the voltmeter to maintain optimal measurement conditions across varying power supply standards without requiring multiple fixed-range voltmeters
3Reliability
If a voltage divider is used to determine effective voltage from individual measurements, then the measurement system can operate independently of AC voltage fluctuations, but the device complexity increases due to additional components
Solution Approach 1:
The regulated DC voltage source serves multiple functions: it provides the reference potential for the voltmeter, it scales the measurement range to accommodate different AC voltage magnitudes, and it stabilizes the measurement system against AC fluctuations. By combining these functions into a single component, the patent achieves reliable independent operation without proportionally increasing device complexity
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 accurate and offset-compensated measurement of AC voltage effective values, independent of AC voltage fluctuations, ensuring reliable operation across different power supply standards and optimizing the measurement range of the voltmeter.
Implementation Method 1
A voltage divider is suspended between the power supply voltage and the ground. There is a first resistance value from the power supply potential to a tap, and there is a second resistance value from the tap to ground.
Implementation Method 2
The DC voltage source adjusts the potential of a ground with respect to the power supply potential.
Data Source
AI summary
A hand-held power tool is disclosed with a measuring system for determining an effective value of an alternating voltage which is fed via an external conductor with respect to a neutral conductor. A regulated direct voltage source has a power supply potential which is referenced to the neutral conductor. There is a first resistance value from the power supply potential to a tap and a second resistance value from the tap to a ground. A voltmeter has a measurement range and its measurement input is connected to the tap. A measurement line connects the tap to the external conductor. The first resistance value is lower than the second resistance value such that the mean voltage value on the tap is equal to the mean of the measurement range for one period of the alternating voltage.