H-Bridge Motor Control Circuit for Reverse Current Protection
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Solution Overview
Problem
In electronic products, the motor driver circuit transistors are damaged due to reverse current recharging the common voltage, exceeding the voltage they can withstand, leading to overheating and damage.
Innovation Solution
A motor controlling circuit with a bridge circuit, driver circuit, controller circuit, and feedback circuit, where the driver circuit adjusts the voltage nodes to prevent current from flowing to the common voltage, using transistors and operational amplifiers to regulate the bridge circuit and ensure the current flows to ground, thereby preventing excessive voltage from damaging the transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the bridge circuit is switched to drive the motor, then the motor operates efficiently, but reverse current flows to the common voltage causing excessive voltage that damages the transistors
Solution Approach 1:
The feedback circuit detects the voltage at the first node before the bridge circuit is switched and generates a feedback signal in advance. This preliminary detection allows the system to prepare protective action before the harmful reverse current can damage the transistors, resolving the contradiction by preventing the reliability issue while maintaining productivity.
Solution Approach 2:
The feedback circuit acts as an intermediary between the bridge circuit and the transistors. It monitors the voltage at the first node and generates feedback signals that mediate the control of the bridge circuit switching, preventing excessive voltage from reaching the transistors while allowing efficient motor operation.
2Device complexity
If the transistors are used to drive the motor without voltage regulation, then the circuit is simple, but the common voltage exceeds the voltage withstand capability of the transistors
Solution Approach 1:
The feedback circuit continuously monitors the voltage at the first node and generates feedback signals based on the detected voltage level. This feedback mechanism regulates the bridge circuit operation to prevent excessive voltage, adding necessary complexity to eliminate the harmful voltage effect while maintaining overall system simplicity.
Solution Approach 2:
The feedback circuit serves as an intermediary control layer between the simple transistor switch and the motor load. It introduces minimal complexity to monitor and regulate voltage, preventing excessive voltage damage without significantly increasing overall circuit complexity.
Data Source
AI summary
A motor controlling circuit is provided. A first terminal of a first high-side transistor and a first terminal of a second high-side transistor are coupled to a common voltage. A first terminal of a first low-side transistor is connected to a second terminal of the first high-side transistor. A first node between the first terminal of the first low-side transistor and the second terminal of the first high-side transistor is connected to a first terminal of a motor. A first terminal of a second low-side transistor is connected to a second terminal of the second high-side transistor. A second node between the first terminal of the second low-side transistor and the second terminal of the second high-side transistor is connected to a second terminal of the motor. The driver circuit regulates at least one of the transistors such that no current flows to the common voltage.