Inverter Gate Voltage Clamping with Delayed Latch Circuit
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Solution Overview
Problem
The existing methods for clamping the gate voltage of IGBTs in inverter systems using Zener diodes can lead to oscillations, increasing the risk of voltage surging and instability, particularly due to the repetition of Zener clamping and cancellation operations.
Innovation Solution
An inverter drive device incorporating a drive circuit that outputs a gate voltage based on a PWM signal, an over-current protection circuit that stops the gate voltage output after a predetermined time, and a Zener clamping protection circuit with a latch circuit that continues clamping for a set interval, allowing for controlled Zener clamping to prevent oscillations and enhance stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If Zener diode clamping is applied to reduce short-circuiting current, then energy during short circuiting is reduced, but gate voltage oscillation occurs
Solution Approach 1:
The patent applies dynamic control by introducing a delay mechanism that activates Zener clamping only after a predetermined time interval following over-current detection. This dynamic timing control prevents immediate clamping that causes oscillation, while still providing protection after the oscillation period has passed, thus resolving the contradiction between energy reduction and voltage stability
Solution Approach 2:
The patent implements preliminary action by detecting over-current conditions first, then waiting for a predetermined time interval before activating the Zener clamping. This preliminary detection and delay phase allows the system to avoid immediate clamping that would cause gate voltage oscillation, while preparing for protective action at the optimal moment
2Reliability
If Zener clamping operation is repeated to suppress over-current, then current protection is improved, but voltage surging increases
Solution Approach 1:
The patent applies periodic action by implementing a predetermined time interval delay before activating Zener clamping. This periodic control mechanism ensures that clamping is not applied immediately or repetitively, but rather after a controlled time delay, thereby preventing the repeated oscillation and voltage surging while maintaining reliable current protection
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 solution enhances the security and stability of the inverter system by preventing voltage oscillations and reducing short-circuit energy, while allowing for precise control of Zener clamping operations to manage over-current conditions effectively.
Implementation Method 1
a Zener clamping protection circuit that acquires the emitter electrode side voltage of the power semiconductor element, and, if that voltage is greater than a second predetermined voltage value that is determined in advance, clamps the gate voltage signal
Data Source
AI summary
An inverter drive device includes a drive circuit that outputs a gate voltage signal of a power semiconductor element; and a Zener clamping protection circuit that acquires an emitter electrode side voltage of the power semiconductor element, and, if that voltage is greater than a predetermined voltage value, performs clamping of the gate voltage of the drive circuit after a predetermined time interval has elapsed from the acquisition of the emitter electrode side voltage. The Zener clamping protection circuit includes a latch circuit that, after the emitter electrode side voltage has been acquired, continues the clamping of the gate voltage by the Zener clamping protection circuit during an interval.