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Infineon DD350N18K | Robust 1800V Dual Diode Module for High-Power Systems
The Infineon DD350N18K is an 1800V, 350A dual diode module engineered for exceptional reliability in high-power conversion systems. While IGBTs often take the spotlight for switching performance, the rectifying and freewheeling diodes that support them are equally critical to system efficiency, robustness, and longevity. The DD350N18K is purpose-built to excel in these demanding roles, providing a rock-solid foundation for industrial-grade power electronics.
- High Voltage Headroom: With an 1800V repetitive peak reverse voltage (V_RRM), this module offers a substantial safety margin for systems operating on 1000V DC or higher buses.
- Superior Current Handling: A 350A average forward current rating ensures stable performance in high-power input rectifiers, brake choppers, and welding applications.
- Optimized Thermal Performance: Housed in a standard industrial package with an isolated baseplate, it is designed for low thermal resistance, enabling efficient heat dissipation and enhanced power cycling capability.
- Soft Recovery Characteristics: Engineered for soft reverse recovery, minimizing voltage overshoots and electromagnetic interference (EMI), which simplifies system design and improves the reliability of associated IGBTs.
Application Scenarios & Engineering Value
The true value of the Infineon DD350N18K is demonstrated in its ability to solve specific engineering challenges across various high-power applications. Its design directly addresses the pain points associated with rectification and braking in modern power systems.
Industrial Motor Drives: In large Variable Frequency Drive (VFD) systems, this module serves as an ideal front-end rectifier, converting three-phase AC input into a stable DC bus. Its robustness handles the high inrush currents during startup, while its low conduction losses contribute to overall drive efficiency. In braking circuits, it provides a reliable path for regenerative energy, protecting the main inverter bridge from overvoltage conditions.
Renewable Energy Inverters: For utility-scale solar and wind power systems, operating at higher DC voltages is key to minimizing transmission losses. The 1800V rating of the DD350N18K makes it a perfect fit for the input stages of these inverters, ensuring long-term reliability in harsh environmental conditions. The module's robust thermal design is critical for managing the variable power profiles inherent in renewables.
Welding and Induction Heating: In high-frequency welding and induction heating power supplies, this diode module is often used in the output rectification stage. Its fast and soft recovery is crucial for maintaining a stable output under dynamic load conditions, directly impacting weld quality and process consistency. Understanding how these components manage heat is vital; unlocking thermal performance through Rth is a key design consideration.
Technical Deep Dive: The Impact of Soft Recovery
A diode's reverse recovery characteristic is one of its most critical dynamic parameters, yet it is often overlooked. When a diode switches from a conducting to a blocking state, a reverse recovery current (I_rr) flows for a short time. An abrupt or "snappy" cessation of this current induces a high di/dt, which interacts with stray inductance in the circuit to create significant voltage spikes (V = L * di/dt). These spikes can exceed the voltage rating of other semiconductors, like the system's core IGBT modules, leading to component failure. The Infineon DD350N18K is engineered for a "soft" recovery, meaning the reverse current decays more gradually. This dramatically reduces voltage overshoots and high-frequency EMI, leading to a more reliable system and often reducing the need for complex and costly snubber circuits.
Key Parameters Overview
For engineers requiring quick-reference data, the table below summarizes the critical performance specifications. For comprehensive details, including characteristic curves and thermal models, download the full datasheet here.
| Parameter | Value |
|---|---|
| Repetitive Peak Reverse Voltage (V_RRM) | 1800 V |
| Average Forward Current (I_FAV) | 350 A (T_C = 80°C) |
| Forward Voltage (V_F) | 1.35 V (Typical at I_F = 350 A, T_vj = 150°C) |
| Surge Forward Current (I_FSM) | 5500 A (t=10ms, T_vj=25°C) |
| Thermal Resistance, Junction to Case (R_thJC) | 0.12 K/W per diode |
| Operating Junction Temperature (T_vj op) | -40 to 150 °C |
Frequently Asked Questions (FAQ)
Why use a dedicated diode module like the DD350N18K instead of an IGBT with an integrated freewheeling diode (FWD)?
While an IGBT's co-packaged FWD is optimized for freewheeling current in an inverter leg, a dedicated diode module like the DD350N18K is superior for applications like input rectification or brake choppers. It offers significantly higher current handling capability, is thermally independent from the IGBTs, and its characteristics (like recovery softness and forward voltage) are specifically optimized for these roles, not as a compromise for a switching device.
What is the primary advantage of the dual diode (series) configuration?
The series connection of two diode dice within a single module provides exceptional high-voltage blocking capability and inherent redundancy. This topology simplifies the design of high-voltage rectifiers and is particularly advantageous in applications demanding high reliability and safety margins, such as in precision servo drives or medium-voltage converters. For application-specific questions or sourcing inquiries, please contact our technical team for expert guidance.
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