Inductor Current Detection Using Transistor Voltage Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for detecting current flowing through an inductor are costly due to the use of expensive precision resistors, result in low accuracy, and inefficient power utilization, especially in low-power circuits.
Innovation Solution
An apparatus using transistors instead of precision resistors to detect current flowing through an inductor, where a charging element and a discharging element with transistors adjust output voltage based on their width to improve detection accuracy and stability, and a detecting element measures current based on output voltages from these transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a precision resistor is used to detect current flowing through an inductor, then current detection can be achieved, but the circuit cost increases and power loss occurs
Solution Approach 1:
The patent extracts the current detection function from the main power path by using a separate sensing resistor connected to the inductor node. The sensing resistor is only connected to ground through a switch that is closed only during detection phases, isolating the sensing function from the continuous power flow and eliminating continuous power loss.
Solution Approach 2:
The patent replaces expensive precision resistors that must maintain constant accuracy with a regular resistor used temporarily only during detection phases. The sensing resistor is activated only when needed for measurement, allowing use of less precise, cheaper components that are activated briefly rather than continuously.
2Loss of energy
If a precision resistor with very small resistance is used to minimize power loss, then power efficiency improves, but the voltage magnitude becomes too small for accurate detection
Solution Approach 1:
The patent uses periodic switching to connect the sensing resistor to ground only during specific detection phases. By closing the switch connected to the sensing resistor only when measurement is needed, the system achieves accurate voltage detection during active phases while maintaining high power efficiency during inactive phases when the switch is open.
Solution Approach 2:
The patent makes the sensing resistor dynamically connected rather than permanently connected. The switch controlled by the control signal dynamically connects or disconnects the sensing resistor from ground based on whether detection is needed, allowing the resistor value to be optimized for both low power loss and sufficient voltage magnitude during detection.
3Reliability
If continuous connection of sensing resistor to ground is used for stable detection, then detection stability improves, but power consumption increases
Solution Approach 1:
The patent implements periodic connection of the sensing resistor to ground through a switch that is closed only during detection phases. This periodic action provides stable detection during active phases while minimizing power consumption during inactive phases, resolving the contradiction between continuous stability and power efficiency.
4Measurement precision
If precision resistor is used for current detection, then current measurement is achieved, but circuit integration becomes difficult and cost increases
Solution Approach 1:
The patent extracts the sensing function into a separate, dedicated component (sensing resistor with switch) that can be independently optimized and integrated. This separation allows the main power circuit to remain simple while the detection function is implemented as a modular add-on, improving overall circuit integration.
Solution Approach 2:
The patent replaces expensive precision resistors with regular resistors used temporarily during detection phases. This substitution reduces component cost and simplifies circuit integration, as regular resistors are easier to integrate and less stringent regarding tolerance requirements when used in periodic rather than continuous applications.
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
The solution reduces power loss, improves circuit stability, and enhances detection accuracy by making the voltage applied to the sensing resistor proportional to the current flowing in the inductor, allowing for highly integrated and efficient current detection.
Implementation Method 1
an inductor can store current and can generate power by outputting stored current
Implementation Method 2
a first transistor of the charging element or a second transistor of the discharging element, which remains turned on all the time, to reduce the output voltage output from the inductor
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The apparatus for detecting current includes: a charging element (110) having one end connected to a power source (VDD) and another end connected to an inductor (L) and configured to charge the inductor with a current; a discharging element (120) having one end connected to the inductor and another end connected to ground potential and configured to discharge the current charged in the inductor; and a detecting element (130) configured to detect a magnitude of a current flowing through the inductor based on a first output voltage output from a first output node of the first charging element (110) when the inductor is charged by the first charging element or on a second output voltage output from a second output node of the second discharging element (120) when the inductor is discharged by the second discharging element.