IGBT Gate Driving Circuit for Fast Soft Interruption
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Solution Overview
Problem
Conventional gate driving circuits for power semiconductor elements face challenges in performing soft interruption during overcurrent and short circuit events, leading to potential device breakdown and noise generation due to prolonged charge dissipation times and high surge voltages.
Innovation Solution
A gate driving circuit design incorporating a sense resistor, overcurrent and short circuit detection circuits, a gate voltage monitoring circuit, and specific MOSFET configurations to rapidly and slowly draw out charges from the gate of the power semiconductor element, ensuring soft interruption and minimizing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional gate driving circuit uses a single MOSFET to draw out charges from the gate, then the circuit structure is simple, but the interruption time is prolonged and device breakdown may occur
Solution Approach 1:
The single MOSFET charge drawing path is segmented into two parallel paths: one with MSOFT for soft interruption and one with MSINK for fast interruption. This segmentation allows the circuit to provide both gentle charge removal (preventing breakdown) and rapid charge removal (reducing interruption time) based on operational needs.
Solution Approach 2:
The circuit dynamically switches between soft interruption mode (MSOFT active) and fast interruption mode (MSINK active) based on the operational state detected by the logic circuit. This dynamic adaptation allows the system to optimize between reliability and speed depending on real-time conditions.
2Speed
If the gate voltage decreases rapidly to interrupt the power semiconductor element, then the interruption speed is fast, but noise and oscillations are generated
Solution Approach 1:
The logic circuit dynamically controls which MOSFET (MSOFT or MSINK) is active based on the operational state. During normal operation, MSOFT is used for gentle, noise-free interruption. During abnormal conditions (overcurrent, short circuit), MSINK is activated for rapid interruption, accepting some noise as necessary for protection.
Solution Approach 2:
The circuit changes the effective resistance parameter by switching between MSOFT (higher resistance for soft interruption) and MSINK (lower resistance for fast interruption). This parameter change allows adaptation of the charge drawing speed to match the operational requirements, balancing speed and noise considerations.
3Object-generated harmful factors
If the gate voltage decreases slowly to perform soft interruption, then noise is suppressed, but the interruption time is prolonged and device breakdown may occur
Solution Approach 1:
The interruption function is segmented into two modes handled by different MOSFETs. MSOFT provides slow, noise-suppressing interruption under normal conditions. MSINK provides fast, protection-oriented interruption under abnormal conditions. The logic circuit segments the operational states to determine which mode to activate.
Solution Approach 2:
The circuit dynamically transitions between soft interruption (MSOFT) and fast interruption (MSINK) based on detected operational conditions. This dynamic switching ensures that noise suppression is maintained during normal operation while rapid protection is available when needed, preventing device breakdown.
4Speed
If overcurrent detection circuit operates without delay, then the response speed is fast, but momentary operation due to noise causes false triggering
Solution Approach 1:
The delay circuit is configured to activate the fast interruption path (MSINK) immediately upon detecting overcurrent or short circuit conditions, while the soft interruption path (MSOFT) is activated after a predetermined delay. This preliminary action ensures that protection is initiated as quickly as possible for severe conditions while allowing noise filtering for less critical situations.
Data Source
AI summary
A gate driving circuit for driving a power semiconductor element can include a MSINK that is an n-channel metal-oxide silicon field-effect transistor (MOSFET) with a low resistance value for rapidly drawing out the charges accumulated on the gate of an insulated gate bipolar transistor (IGBT), and a MSOFT that is an n-channel MOSFET with a high resistance value for slowly drawing out the charges. By shifting the time for turning ON of these MOSFETs, soft interruption can be performed rapidly and surely when overcurrent or short circuit current flows in the IGBT. Therefore, device breakdown is minimized or avoided and noise generation is suppressed.