Switched Inductive Gate Drive for Below-Ground Turn-Off Control
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Solution Overview
Problem
Existing power conversion and power supply circuitry face challenges in reliably switching high voltages due to switching induced transients that can cause unintended device turn-on or turn-off, particularly in bridge topologies like half-bridge and full-bridge configurations, which often use insulated gate bipolar transistors (IGBTs) and require effective gate drive to mitigate transient noise.
Innovation Solution
The implementation of a switched inductive storage element, such as an inductor, is used to enhance gate drive by switching between a supply node and a gate node of the gated device, allowing the inductive storage element to drive the gate below the local ground potential, thereby mitigating parasitic turn-on during the off-state of high-side and low-side devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional gate drive circuits are used in bridge topologies, then the circuit structure is simple, but switching induced transients cause unreliable device turn-off and parasitic turn-on
Solution Approach 1:
An inductive storage element is introduced as an intermediary component between the gate driver and the gated device. This inductor stores energy during the on-state and releases it during the off-state to provide a negative voltage pulse that actively suppresses parasitic turn-on, thereby improving turn-off reliability without requiring complex control circuitry
Solution Approach 2:
The inductive storage element is pre-charged during the on-state before the turn-off event occurs. This preliminary energy storage ensures that when the device turns off, the stored energy is immediately available to counteract switching transients and prevent parasitic turn-on, addressing the reliability issue before it manifests
2Object-affected harmful factors
If isolation methods (reverse biased junctions or galvanic isolation) are used to separate high-side and low-side gate drivers, then transient noise between drivers is reduced, but device complexity and component count increase
Solution Approach 1:
The harmful transient noise coupling path between high-side and low-side gate drivers is extracted and eliminated by using the inductive storage element to actively control the gate voltage, removing the need for complex isolation components like optocouplers or reverse biased junctions
3Reliability
If the inductive storage element drives the gate below local ground potential, then parasitic turn-on is mitigated, but the gate drive circuit requires additional voltage headroom
Solution Approach 1:
The inductive storage element operates in periodic cycles, being charged during the on-state and discharged during the off-state. This periodic operation allows the circuit to reuse the same voltage rails and components, managing voltage headroom requirements through time-multiplexed operation rather than requiring permanently elevated voltage levels
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 approach effectively reduces switching induced transients, preventing unintended device turn-on and enhancing the reliability of power device operation in high-voltage applications by using inductive storage elements to manage gate drive during turn-off.
Implementation Method 1
an inductive storage element, such as an inductor, is used to enhance gate drive by switching between a supply node and a gate node
Data Source
AI summary
A switched inductive storage element to enhance gate drive at turn-off is described herein. An inductive storage element (e.g., an inductor) may be switched between a supply node and a gate node of a gated device (e.g., a low-side device and/or a high-side device). While coupled to the supply node, the inductive storage element may be energized; and subsequently, while coupled to the gate node of the gated device, the inductive storage element may drive the gate node (i.e., the gate of the low-side and/or high-side device) below the local ground potential.