External Switch Drive Adjustment for Fast Switching With EMI Tradeoff
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Solution Overview
Problem
Existing motor drive systems face challenges in efficiently controlling the switching times of conductivity modulated devices, leading to increased switching losses, temperature, and electromagnetic interference (EMI).
Innovation Solution
A system controller adjusts the drive characteristics of conductivity modulated devices by varying the magnitude of the drive current, thereby reducing turn-on and turn-off times, which minimizes switching losses and temperature while tolerating higher EMI during temporary power delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the switching time of conductivity modulated devices is reduced, then switching losses and temperature are reduced, but electromagnetic interference increases
Solution Approach 1:
The patent implements dynamic adjustment of drive current magnitude based on operating conditions. The controller varies the drive current magnitude to optimize the trade-off between switching speed and EMI, allowing the system to adaptively balance switching losses reduction against electromagnetic interference generation in different operational states
Solution Approach 2:
The patent changes the magnitude of drive current as a controllable parameter to influence switching characteristics. By adjusting this parameter, the system can control the rate of change of current through the conductivity modulated device, thereby managing both switching losses and EMI generation during transitions
2Loss of time
If the drive current magnitude is increased to reduce turn-on and turn-off times, then switching losses are reduced, but electromagnetic interference increases
Solution Approach 1:
The system dynamically adjusts drive current magnitude based on real-time operating conditions rather than using a fixed high current. This allows rapid switching when needed while limiting EMI generation during normal operation, optimizing the balance between switching speed and electromagnetic interference
Solution Approach 2:
The controller applies periodic or pulsed drive current adjustments during switching transitions. By using controlled current pulses with optimized magnitude and duration, the system achieves fast turn-on and turn-off times while limiting the overall EMI exposure through time-limited high-current application
3Loss of energy
If switching losses are reduced by optimizing switching times, then energy efficiency is improved, but control complexity increases
Solution Approach 1:
The system incorporates feedback mechanisms that monitor operating conditions and adjust drive current magnitude accordingly. This feedback loop enables automatic optimization of switching losses without requiring complex manual tuning or control algorithms, as the system self-adjusts based on sensed parameters
Solution Approach 2:
The controller automatically manages the optimization of switching times and current magnitudes without external intervention. The system serves itself by internally adjusting drive parameters to minimize switching losses based on its own operating state, reducing the need for complex external control systems
Data Source
AI summary
A switch controller configured to control a transistor. The switch controller comprising an interface configured to receive a command signal from a system controller. The command signal is representative of a first command to control the transistor with a first drive strength or a second command to control the transistor with a second drive strength. The switch controller is configured to adjust a fall time or a rise time, or both, of a voltage across the transistor and apply the first drive strength or the second drive strength for at least a portion of the fall time or the rise time, or both in response to the command signal. The fall time or the rise time, or both in response to the second command is shorter than the fall time or the rise time, or both in response to the first command.