Work Machine Current Measurement Using Variable Reference Voltage
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Solution Overview
Problem
Electric powered work machines require high reliability for current measurement, but mounting two independent current measurement circuits increases component count and footprint, necessitating a more efficient solution.
Innovation Solution
An electric powered work machine configuration that includes a motor, manual switch, electric current path, shunt resistor, reference voltage generation circuit, and electric current measurement circuit, where the reference voltage varies to indicate the presence of electric current, allowing for high reliability measurement without an additional current measurement circuit, and includes diagnosis and overcurrent detection circuits for accurate operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two independent electric current measurement circuits are mounted to ensure high reliability, then measurement reliability is improved, but device complexity and footprint increase
Solution Approach 1:
The patent merges the function of two independent current measurement circuits into a single measurement circuit by combining it with a reference voltage generation circuit. The measurement circuit receives both a measured voltage (proportional to current) and a reference voltage, then outputs an output voltage that represents the current measurement. This integration eliminates the need for a second independent measurement circuit while maintaining measurement reliability through the reference voltage comparison mechanism.
Solution Approach 2:
The single electric current measurement circuit is designed to perform multiple functions: it measures the actual current through the shunt resistor and simultaneously compares it against a generated reference voltage. This multi-functional design allows one circuit to accomplish what traditionally required two separate circuits, reducing overall system complexity while ensuring reliable measurement through the reference comparison approach.
2Reliability
If two independent electric current measurement circuits are mounted to ensure high reliability, then measurement reliability is improved, but the footprint for additional components increases
Solution Approach 1:
The patent merges the function of two independent current measurement circuits into a single measurement circuit by combining it with a reference voltage generation circuit. The measurement circuit receives both a measured voltage (proportional to current) and a reference voltage, then outputs an output voltage that represents the current measurement. This integration eliminates the need for a second independent measurement circuit while maintaining measurement reliability through the reference voltage comparison mechanism.
3Device complexity
If a single electric current measurement circuit is used without reference voltage variation, then device complexity is reduced, but measurement reliability deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the measurement circuit continuously compares the measured voltage (representing actual current) against a reference voltage that can be varied under different conditions. The circuit adjusts its operation based on this comparison, ensuring reliable measurements by detecting discrepancies between expected and actual values. This feedback approach enables a single circuit to achieve the reliability previously requiring two independent circuits.
Solution Approach 2:
The reference voltage generation circuit varies the reference voltage parameter under different operating conditions (such as when the first condition is established versus when it is not). By dynamically adjusting the reference voltage parameter, the measurement circuit can adapt to different states and maintain measurement reliability without requiring multiple independent circuits. This parameter variation enables the single circuit to perform reliability checks that would otherwise require redundant hardware.
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
Enables high reliability electric current measurement without additional components, suppresses inaccurate measurements, and provides accurate diagnosis and overcurrent detection, reducing the need for extra circuits and components.
Implementation Method 1
The measured voltage is generated across the shunt resistor in response to an electric current flowing through the shunt resistor
Data Source
AI summary
An electric powered work machine according to one aspect of the present disclosure includes: a tool; a motor; a manual switch; an electric current path; a shunt resistor; a reference voltage generation circuit; and an electric current measurement circuit. The reference voltage generation circuit (i) generates a reference voltage having a first magnitude in response to a first condition being established, and (ii) generates the reference voltage having a second magnitude in response to the first condition not being established. The electric current measurement circuit (i) receives the reference voltage and a measured voltage, and (ii) outputs an output voltage based on the reference voltage and the measured voltage.