Motor Driver IC Back-EMF Voltage Protection
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Solution Overview
Problem
The existing motor driver apparatuses have a high number of external components attached to the semiconductor integrated circuit, which increases complexity and reduces reliability due to the presence of components like zener diodes and decoupling capacitors needed to manage back electromotive force and voltage variations.
Innovation Solution
A motor driver apparatus with a semiconductor integrated circuit that includes a signal generating part to indicate back electromotive force periods, a removing part to detect and remove voltage variations through differential amplification, and a limiting part to control the power-supply voltage within predetermined limits, using MOS transistors and comparators to manage voltage effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If zener diode and decoupling capacitor are added to prevent voltage exceedance, then the power terminal voltage is protected from exceeding withstand voltage, but the number of external parts increases
Solution Approach 1:
The patent integrates the voltage protection function into the motor driver IC itself by incorporating a protection circuit that includes a voltage detection unit and a clamping circuit. This merges the previously external zener diode and decoupling capacitor functions into the integrated circuit, eliminating the need for separate external protection components while maintaining voltage protection capability.
Solution Approach 2:
The motor driver IC performs self-protection by incorporating an internal voltage detection mechanism that monitors the power terminal voltage and automatically activates a clamping circuit when voltage exceeds the withstand voltage threshold. This self-service approach eliminates the need for external protection components to perform the same function.
2Reliability
If decoupling capacitor with greater capacity is added to delay voltage increment, then voltage variation is suppressed, but the number of external parts increases
Solution Approach 1:
The patent integrates the decoupling capacitor function into the internal circuitry of the motor driver IC. The voltage detection unit monitors power terminal voltage and the internal clamping circuit responds to suppress voltage variations, merging the previously external decoupling capacitor functionality into the integrated circuit structure.
Solution Approach 2:
The motor driver IC performs self-regulation of voltage variations through its internal detection and clamping circuits, eliminating the need for external decoupling capacitors. The system monitors its own power terminal voltage and automatically corrects variations without requiring external passive components.
3Reliability
If multiple external components are used to manage back electromotive force, then voltage protection is achieved, but the circuit complexity and part count increase
Solution Approach 1:
The patent consolidates back electromotive force management functionality into the motor driver IC by integrating the voltage detection unit, comparison circuit, and clamping circuit within the same integrated circuit package. This merges multiple previously separate external components into a single integrated solution, reducing both part count and circuit complexity while maintaining protection capability.
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 reduces the number of external components required, enhancing reliability and efficiency by effectively managing back electromotive force and voltage variations within the semiconductor integrated circuit, thereby preventing voltage exceedance and maintaining the integrity of the motor driver system.
Implementation Method 1
the inductor of the winding wire of the direct-current motor 23 generates a back electromotive force at a timing when the first state where the MOS transistors M1 and M4 are turned on and the MOS transistors M2 and M3 are turned off
Implementation Method 2
the removing part (41, 42, Cr, M5) detects a voltage variation generated in a power-supply voltage by the back electromotive force generated by the direct-current motor during the back electromotive force generation period indicated by the indication signal
Implementation Method 3
A zener diode is added to prevent the voltage VDD of the power terminal from exceeding the withstand voltage
Data Source
AI summary
A motor driver apparatus that is formed of a semiconductor integrated circuit which is supplied with an electric power and drives a direct current motor includes a signal generating part that generates an indication signal for indicating a back electromotive force generation period while the direct current motor generates a back electromotive force, a removing part that detects a voltage variation generated in a power-supply voltage by the back electromotive force generated by the direct-current motor during the back electromotive force generation period indicated by the indication signal, and removes the detected voltage variation, and a limiting part that limits the power-supply voltage so as to be less than a predetermined voltage at a speed higher than that in the removing part.