Variable Impedance Circuit for Surge Absorption in Motor Drivers
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Solution Overview
Problem
Switching operations in electronic circuits, such as those driving motors, often generate surge voltages and ringing, leading to switching losses, equipment failures, and noise, which existing technologies inadequately address.
Innovation Solution
An electronic circuit incorporating a diode, a capacitor, and a first variable impedance circuit that increases impedance between the transistor's control electrode and a reference voltage node in response to surge currents, effectively absorbing surge voltages and currents by raising the gate voltage of the transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a switching element is turned on or off to drive a motor, then the motor can be controlled, but surge voltage and ringing are generated causing switching loss and noise
Solution Approach 1:
The capacitor is pre-charged to a predetermined voltage before the switching element turns off. This preliminary action ensures that when the surge occurs, the capacitor is already in a state to immediately absorb the surge current, preventing switching loss without affecting normal motor control operation
Solution Approach 2:
The capacitor acts as an intermediary element between the switching element and the motor circuit. It mediates the surge current by providing a temporary energy storage path, absorbing the surge current when the switching element turns off, thereby preventing direct feedback to the switching element and reducing switching loss
2Productivity
If a switching element is turned on or off to drive a motor, then the motor can be controlled, but surge voltage and ringing cause equipment failure and noise
Solution Approach 1:
The capacitor is pre-charged to a predetermined voltage before the switching element turns off. This preliminary action ensures that when the surge occurs, the capacitor is already in a state to immediately absorb the surge current, preventing equipment failure without affecting normal motor control operation
Solution Approach 2:
The capacitor provides beforehand cushioning by being pre-charged to absorb the impending surge current. This cushioning effect protects the switching element and surrounding circuitry from damage caused by surge voltage and ringing, thereby improving equipment reliability
3Productivity
If a switching element is turned on or off to drive a motor, then the motor can be controlled, but surge voltage and ringing generate noise
Solution Approach 1:
The capacitor acts as an intermediary element that absorbs the surge current and prevents it from oscillating in the circuit. By providing a dedicated energy absorption path, the capacitor eliminates the ringing effect that generates electromagnetic noise, thereby reducing noise without affecting motor control functionality
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 configuration significantly reduces surge voltages and ringing, enhancing the circuit's ability to quickly absorb and manage surge currents, thereby preventing equipment failures and noise.
Implementation Method 1
a capacitor (C1) connected between a cathode of the diode and a control electrode of the first transistor
Implementation Method 2
a diode (D1) connected between a drain and the control electrode of the first transistor, and having a forward direction in which a current flows from the drain to the control electrode
Data Source
AI summary
An electronic circuit includes a diode configured to carry a surge current generated by switching of a first transistor, a capacitor connected between a cathode of the diode and a control electrode of the first transistor, and a first variable impedance circuit configured to vary an impedance between the control electrode of the first transistor and a first reference voltage node according to the surge current flowing to the diode.