SKKH 570/18 E: A Robust Thyristor/Diode Module for High-Power AC Control
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Semikron SKKH 570/18 E: Thyristor/Diode Module for AC Control
High-Reliability Power Control with Superior Thermal Performance
The Semikron SKKH 570/18 E is a Thyristor/Diode Module engineered for robust and precise control of high-power, line-frequency applications. Housed in the industry-standard SEMIPACK® 5 package, its primary value is delivering exceptional reliability through a high isolation voltage and efficient thermal management. This module is not designed for high-frequency switching, but rather for rugged AC power control where durability and fault tolerance are critical design parameters. For engineers developing systems that require dependable performance under heavy electrical and thermal loads, this module provides a proven foundation.
- Core Specifications: 1800V | 555A (ITAVM) | 3000V (Visol)
- Key Advantages: High electrical cycling capability, simplified thermal design due to low thermal resistance.
This module directly addresses the need for dependable components in high-power controlled rectifiers and AC motor soft starters.
Download Official Datasheet (PDF)
Technical Analysis for System Integration
The SKKH 570/18 E is built upon a foundation of technologies that ensure long-term operational stability. The use of glass passivated thyristor chips is a critical feature, providing a hermetic seal for the silicon junctions. This passivation protects against environmental contaminants and moisture, which is essential for maintaining the high blocking voltage of 1800V over the module’s entire lifespan. Furthermore, the device utilizes precious metal pressure contacts instead of soldered wire bonds internally. This construction method significantly enhances its resistance to mechanical stress and thermal cycling fatigue, a common failure point in high-power modules.
A key parameter for any high-power module is its ability to dissipate heat. The SKKH 570/18 E features a low junction-to-case thermal resistance (Rth(j-c)) of 0.069 K/W per chip. This value can be thought of as the width of a pipe for heat flow; a lower number indicates a wider pipe, allowing heat to move easily from the active silicon to the heatsink. This efficiency, enabled by the aluminum nitride ceramic baseplate, simplifies the cooling system design and allows the module to operate reliably at its maximum average on-state current of 555 A (at a case temperature of 73°C). For a deeper understanding of thermal design, review this guide on mastering IGBT thermal design.
Optimized Application Scenarios
The electrical and mechanical characteristics of the SKKH 570/18 E make it highly suitable for specific industrial applications:
- AC Motor Soft Starters: The module’s high surge current rating (ITSM) of 15500A allows it to safely manage the inrush current of large induction motors during startup.
- Controlled Rectifiers: With a repetitive peak voltage of 1800V, it provides a substantial safety margin for building controlled rectifiers for DC motor drives or power supplies operating on 400V and 690V AC lines.
- High-Power Temperature Control: For industrial furnaces and other resistive heating applications, the module’s high continuous current rating enables precise and reliable phase-angle control of the heating elements.
- Welding Power Supplies: The robust pressure contact system and surge current handling make it a durable component for managing high-current pulses in certain welding applications.
This module is an optimal choice for line-frequency power control systems where high reliability and thermal stability are the primary engineering goals.
Key Specifications of the SKKH 570/18 E
| Parameter | Value | |
|---|---|---|
| Absolute Maximum Ratings | Repetitive Peak Reverse/Off-State Voltage (VRRM, VDRM) | 1800 V |
| Average On-State Current (ITAV @ Tcase=73°C) | 555 A | |
| Surge On-State Current (ITSM, 10 ms, 50 Hz) | 15500 A | |
| Operating Junction Temperature (Tvj op) | -40 to +130 °C | |
| Thyristor Characteristics (at Tj=130°C) | Threshold Voltage (VT(TO)) | 0.78 V |
| Slope Resistance (rT) | 0.32 mΩ | |
| Peak Gate Current (IGM) | 10 A | |
| Thermal and Mechanical | Insulation Test Voltage (Visol, 50 Hz, 1 min.) | 3000 V (RMS) |
| Thermal Resistance, Junction to Case (Rth(j-c) per chip) | 0.069 K/W | |
| Mounting Torque (Case to Heatsink, M10) | 10.2 … 13.8 Nm | |
Engineer’s FAQ
What are the primary considerations for heatsink selection for the SKKH 570/18 E?
Heatsink selection depends on the expected power dissipation. First, calculate the total power loss using the on-state characteristics (VT(TO) and rT) and the load current profile from the datasheet curves. Then, use the thermal resistance from junction to case (Rth(j-c)) and case to heatsink (Rth(c-s)) along with the maximum allowable junction temperature to determine the required thermal resistance of the heatsink (Rth(s-a)).
What is the correct mounting procedure for this module?
Ensure the heatsink surface is clean and flat. Apply a thin, even layer of thermal compound. Mount the module to the heatsink using M10 bolts, tightening them to the specified torque of 10.2 to 13.8 Nm to ensure optimal thermal contact. Connect the power terminals (M6) to a torque of 4.25 to 5.75 Nm. Incorrect torque can lead to poor thermal performance or mechanical stress.
How does the half-bridge (thyristor/diode) configuration work?
This configuration, also known as a common cathode connection, is used for single-phase AC control. The thyristor acts as a controlled switch for one half of the AC waveform, while the diode provides an uncontrolled return path (freewheeling) for the other half. This is a common topology for controlled rectifiers and AC voltage controllers.
Why use a thyristor module instead of a more modern IGBT module?
While IGBTs excel at high-frequency switching for applications like VFDs, thyristors offer superior robustness, higher surge current capability, and simpler control for line-frequency (50/60 Hz) applications. They are inherently more tolerant to line voltage transients and load faults, making them the preferred choice for applications like soft starters and high-power rectifiers where switching speed is not a priority but reliability is.
Enabling Robust Power System Design
The SKKH 570/18 E provides a highly reliable component for power electronics engineers. Its combination of a high voltage rating, robust internal construction with pressure contacts, and excellent thermal transfer characteristics allows for the design of durable and efficient AC power control systems. The module’s proven SEMIPACK® 5 housing ensures straightforward integration into new and existing industrial equipment.