Motor Drive Circuit With Current Cutoff for Switch Timing Errors
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Solution Overview
Problem
Conventional drive devices for vehicles face issues with prolonged large current flow due to delayed switching timing, leading to potential short-circuits and inefficiencies, especially when upstream and downstream switches are mistakenly activated.
Innovation Solution
Incorporating a current detection circuit and stop circuit that detect currents exceeding thresholds, immediately stopping the flow when excessive current is detected, and utilizing a voltage detection circuit to diagnose switch states and prevent erroneous long-term current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If four drive circuits are used to control switching of upstream and downstream switches, then the motor can rotate in forward and reverse directions, but the microcomputer processing delay causes incorrect switching timing and prolonged large current flow
Solution Approach 1:
The patent implements feedback mechanisms where current detection circuits continuously monitor current flow and provide real-time signals to stop circuits. When abnormal current conditions are detected (indicating incorrect switch configuration), the stop circuit immediately interrupts current flow. This closed-loop feedback system compensates for microcomputer processing delays by providing direct hardware-level monitoring and response, ensuring reliable operation despite software processing limitations.
2Device complexity
If switching timing is delayed due to microcomputer processing, then control complexity is reduced to a single microcomputer, but large current flows for extended periods causing potential short-circuits
Solution Approach 1:
The patent introduces intermediary components between the microcomputer and the power switches: current detection circuits act as intermediaries that sense current conditions and translate them into actionable signals, while stop circuits serve as intermediary protection mechanisms that can immediately interrupt current flow without waiting for microcomputer processing. This intermediary layer provides rapid response to abnormal conditions, preventing harmful effects while maintaining the simplicity of single-microcomputer control architecture.
3Ease of operation
If upstream and downstream switches are mistakenly activated simultaneously, then circuit control is simplified, but the DC power supply short-circuits and large current flows indefinitely
Solution Approach 1:
The patent implements preliminary anti-action through stop circuits that are pre-configured to detect and prevent incorrect switch configurations before they can cause harmful effects. The current detection circuits continuously monitor for conditions indicating mistaken activation (such as both upstream and downstream switches being on), and the stop circuits are ready to immediately interrupt current flow upon detection. This preemptive protection mechanism prevents short-circuits and indefinite large current flow while maintaining simple switch control logic.
Data Source
AI summary
A drive device drives a motor serving as a load. A first upstream switch is disposed upstream from the motor and a first downstream switch is disposed downstream from the motor in a first current path of current flowing via the motor. A second upstream switch is disposed upstream from the motor and a second downstream switch is disposed downstream from the motor in a second current path of current flowing via the motor. A direction of the current flowing in the motor when current flows in the first current path is different from a direction of the current flowing in the motor when current flows in the second current path. The first upstream drive circuit stops flow of current via the first upstream switch when the current flowing through the first upstream switch becomes greater than or equal to a current threshold.