Semiconductor Motor Driver Back-EMF Suppression Circuit
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Solution Overview
Problem
Existing motor driving control methods using microcontrollers face challenges in immediately suppressing back electromotive force when current control in the field coil is lost, leading to potential component damage due to software processing delays in interrupt handling.
Innovation Solution
A semiconductor device with dedicated switching circuits and a position detection section that outputs signals to control the connections between the coil ends and the power supply, allowing for immediate switching and regeneration of current, thereby preventing back electromotive force buildup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If software interrupt processing is used to detect overcurrent and control switching elements, then the control logic is flexible and programmable, but there is a time lag that prevents immediate suppression of back electromotive force
Solution Approach 1:
The patent replaces software-based interrupt processing with a hardware-based comparator circuit that directly monitors current and automatically triggers switching element control. The comparator (detecting section) continuously compares the current flowing through the field coil with a reference value, and when overcurrent is detected, it immediately outputs a signal to turn off the switching elements, eliminating the time lag inherent in software processing while maintaining programmable control thresholds through the reference voltage input.
Solution Approach 2:
The patent introduces a comparator circuit as an intermediary hardware component between the current sensing element and the switching element control. This intermediary hardware mediator processes the current detection and generates control signals instantaneously, bridging the gap between current monitoring and switching control without requiring software intervention, thus resolving the time lag while preserving control flexibility through adjustable reference values.
2Reliability
If current control in the field coil is lost, then the motor may operate abnormally, but immediate cutoff of field coil current is necessary to prevent serious accidents
Solution Approach 1:
The patent implements preliminary anti-action by continuously monitoring the current through the field coil using a comparator that compares the actual current with a predetermined reference value. When the current exceeds the reference value indicating loss of control, the comparator immediately outputs a signal to turn off the switching elements, preventing the buildup of dangerous back electromotive force before it can cause damage to connected components.
Solution Approach 2:
The patent establishes a feedback control mechanism where the current flowing through the field coil is continuously sensed and fed back to the comparator circuit. The comparator compares this feedback current signal with a reference value and automatically adjusts the switching element state to maintain current within safe limits, providing real-time protection against overcurrent conditions and back electromotive force damage.
3Use of energy by moving object
If electrification of the motor stops while the motor is turning, then power consumption is reduced, but current remaining in the coil produces back electromotive force that raises power supply potential and may damage components
Solution Approach 1:
The patent maintains continuous protective action by keeping the comparator circuit actively monitoring the field coil current even when motor electrification stops. The comparator continues to detect current flow and immediately triggers switching element turn-off if any current is detected, ensuring that the harmful back electromotive force is suppressed continuously without interruption, while allowing the motor to consume minimal power during non-operational states.
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 effectively suppresses back electromotive force without time lag, preventing component damage and ensuring safe motor operation even when current control is lost.
Implementation Method 1
a position detection section that detects changes in a turning position of a rotor provided at the motor and outputs detection signals corresponding to the changing turning position
Implementation Method 2
controls current flowing in the coil with the first switching circuit and the second switching circuit
Implementation Method 3
current remaining in the coil produces a back electromotive force and the potential of a power supply is raised
Data Source
AI summary
A semiconductor device that controls a motor driving device. The semiconductor device includes: a position detection section that detects changes in a turning position of a rotor provided at a motor and outputs detection signals corresponding to the changing turning position; a first switching section that, in accordance with the detection signals, outputs ground switching signals, which switch which end portion of a coil is connected to a ground side, to a first switching circuit; and a second switching section that, in accordance with the detection signals, outputs connection switching signals, which switch which end portion of the coil is connected to a driving power supply side, to a third switching circuit that controls the switching of connections between the end portions of the coil and the driving power supply side by a second switching circuit.