Load Current Measurement Using Switch Control Variable
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Solution Overview
Problem
Existing methods for measuring load current in low-voltage load circuits require a measuring resistor, which leads to unfavorable power loss due to the need for a high resistance, and existing solutions are not efficient in detecting load current without a separate measuring element.
Innovation Solution
A device that uses a switch with a control variable and an output variable, where the adjusting means keeps the output variable constant, and the evaluation means determines the load current from the control variable, eliminating the need for a separate measuring element by utilizing the switch itself to measure the load current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a measuring resistor with high resistance is used to measure load current in low-voltage circuits, then the voltage drop across the measuring resistor is sufficient for measurement, but the power loss in the measuring resistor increases
Solution Approach 1:
The invention extracts the measurement function from a separate measuring resistor and integrates it into the switch itself. The switch's inherent on-resistance serves as the measuring element, eliminating the need for an additional measuring resistor that would cause power loss. The control unit measures the voltage drop across the switch during its on-state to determine load current.
Solution Approach 2:
The switch is given dual functionality: it serves both as the load switching element and as the measuring element for load current detection. By utilizing the switch's own resistance characteristics for measurement purposes, the invention eliminates the need for dedicated measuring components, thereby reducing overall power loss while maintaining measurement capability.
2Measurement precision
If a separate measuring element is integrated into the load circuit, then the load current can be measured, but the device complexity increases
Solution Approach 1:
The invention merges the measurement function with the existing switch component in the load circuit. Instead of adding a separate measuring element, the control unit utilizes the switch's inherent electrical characteristics (voltage drop across the switch) to determine load current, thereby avoiding additional hardware and reducing circuit complexity.
Solution Approach 2:
The switch serves itself by providing measurement data through its own voltage drop characteristics. The control unit extracts load current information directly from the switch's operational parameters without requiring external measuring elements, making the system self-measuring and reducing overall 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 approach reduces power loss in the load circuit by eliminating the need for a measuring resistor and allows for accurate determination of load current, while also detecting overload conditions and polarity reversals, thereby enhancing safety and efficiency.
Implementation Method 1
a switch with a characteristic curve, which is provided for switching the load current and which has a control variable and an output variable that is dependent on the control variable
Implementation Method 2
an adjusting means for keeping the output variable constant at a predetermined value
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a device (2) for measuring a load current (I) in a load circuit (6), comprising a switch (10) for switching the load current (I) and having a control variable and an output variable dependent on the control variable, an actuating means (24) for maintaining the output variable at a predetermined value, and an evaluation means (28) for determining the load current (I). It is proposed that the actuating means (24) for maintaining the output variable at a predetermined value while the current through the switch (10) varies, and the evaluation means (28) for determining the load current (I) from the control variable, be provided. An additional measuring element for measuring the load current (I) can be omitted, thereby keeping power loss low.