Smart Gate Driver Soft Shutdown for Overcurrent Faults
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Solution Overview
Problem
Existing drive circuits for electric motors in large moving work machines face challenges in managing overcurrent conditions, leading to potential damage due to high voltage overshoot during hard shutdowns, which can occur from failures in power devices or high-inductance short circuits.
Innovation Solution
Implementing a soft shutdown mechanism using smart gate driver circuits and over-current detection circuits to gradually deactivate power devices, ensuring isolation across different voltage domains, thereby reducing voltage overshoot and protecting equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hard shutdown is used to protect against overcurrent conditions, then equipment damage is prevented, but voltage overshoot increases causing additional damage
Solution Approach 1:
The patent applies dynamics by transitioning from a static hard shutdown approach to a dynamic soft shutdown approach. The gate driver circuit gradually reduces the gate voltage of power devices over time when an overcurrent condition is detected, rather than immediately cutting off power. This dynamic control allows the system to adapt to fault conditions while minimizing voltage overshoot that would occur with abrupt shutdown, thus resolving the contradiction between protection reliability and voltage overshoot harm.
Solution Approach 2:
The patent implements beforehand cushioning by preparing a controlled shutdown sequence in advance of actual equipment damage. The soft shutdown mechanism pre-establishes a gradual deactivation protocol that cushions the system against the harmful effects of abrupt power interruption. When overcurrent is detected, this pre-planned cushioning action reduces voltage spikes and overshoot that would otherwise cause additional equipment damage, while still achieving the ultimate protection goal.
2Power
If system voltage is increased to improve power delivery, then power capability is enhanced, but vulnerability to voltage overshoot damage increases
Solution Approach 1:
The patent applies feedback by implementing overcurrent detection circuits that continuously monitor system conditions and provide real-time information to the controller. When overcurrent or fault conditions are detected, the feedback signal triggers the soft shutdown sequence, which gradually reduces power device activation. This feedback mechanism allows the system to operate at higher voltages for improved power capability while automatically responding to fault conditions to prevent voltage overshoot damage, thus resolving the contradiction between power enhancement and vulnerability reduction.
3Object-affected harmful factors
If smart gate driver circuits with soft shutdown are implemented, then voltage overshoot is reduced, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the smart gate driver circuit to perform multiple functions within a single integrated component. The gate driver not only provides standard power device control but also incorporates overcurrent detection input, soft shutdown sequencing, and protective functionality. This multi-functional approach reduces voltage overshoot while minimizing the addition of separate discrete protection circuits, thus addressing the contradiction between voltage overshoot reduction and device complexity by consolidating functions rather than adding separate complex subsystems.
Data Source
AI summary
A drive circuit includes power devices that provide current to a load. At least a portion of the power devices are disposed in a first voltage domain of the drive circuit; a controller circuit configured to provide control signals to activate and deactivate the power devices, wherein the controller circuit is disposed in a second voltage domain separated from the first voltage domain by a first voltage isolation barrier; a smart gate driver configured to transfer a control signal from the second voltage domain to another voltage domain; and an over-current detection circuit disposed in the first voltage domain and configured to produce a fault signal when detecting a current fault condition of the power devices and send the fault signal as a soft-shutdown signal to the smart gate driver. The smart gate driver performs a soft-shutdown of the power devices in response to the soft-shutdown signal.