Motor Current Protection Circuit Using Switch Voltage Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional motor current detecting circuits in fan systems consume additional power due to resistors, which is inefficient and not optimal for precise control of rotational speed for heat management in electronic devices.
Innovation Solution
A motor current protecting circuit comprising an output stage with high-side and low-side switches, a voltage calculating circuit, a control circuit, and a driver circuit, which determines switch states and voltage differences to manage motor current within thresholds, reducing power consumption and improving control precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a resistor is used in the conventional detector circuit to detect motor current, then the motor current can be detected, but additional power consumption is generated by the resistor
Solution Approach 1:
The patent extracts the power-consuming resistor from the detection circuit and replaces it with a current detecting circuit that has negligible power consumption. The resistor is removed while retaining the current detection capability through alternative means (current detecting circuit connected to motor terminals), thus eliminating the harmful power consumption while preserving the measurement function.
Solution Approach 2:
The patent substitutes the passive resistor-based detection mechanism with an active current detecting circuit that uses voltage measurement and calculation to infer current. Instead of using a physical resistor to create a measurable voltage drop (which consumes power), the system uses a high-impedance voltage measuring circuit to detect voltage at motor terminals and calculates current from these voltage readings, replacing the power-consuming mechanical/electrical resistor element with a non-invasive measurement approach.
2Productivity
If the conventional control circuit switches the bridge circuit based on current or voltage values, then the motor can be controlled, but the control precision is insufficient for precise rotational speed control
Solution Approach 1:
The patent implements a feedback mechanism where the current detecting circuit continuously monitors motor current through voltage measurement at motor terminals, and the control circuit adjusts the bridge circuit switching based on this real-time feedback. The system measures voltage, calculates current, compares it with desired values, and adjusts switching accordingly, creating a closed-loop control system that achieves precise rotational speed control through continuous feedback adjustment.
Solution Approach 2:
The patent performs preliminary voltage measurement and current calculation before executing control switching actions. The current detecting circuit预先 (in advance) measures the voltage at motor terminals and calculates the current value, which then informs the control circuit's switching decisions. This preliminary detection and calculation phase ensures that control actions are based on accurate, up-to-date current information, improving control precision.
Data Source
AI summary
A motor current protecting circuit is provided. A voltage calculating circuit determines whether or not each of low-side switches is fully turned on and then determines whether or not a voltage difference between a first terminal and a second terminal of each of the low-side switches being fully turned on is larger than or equal to a zero value. The voltage calculating circuit adds up the voltage differences each of which is larger than or equal to the zero value to output a voltage signal. A control circuit controls a driver circuit to switch the low-side switches and high-side switches according to the voltage signal.