Technology Offers

S3L-Inverter: Switching-loss-free 3-level pulse-controlled inverter with snubber circuit

Abstract

The new Soft Switching Three Level Inverter (S3L–Inverter) is of striking simplicity and is therefore inexpensive. Because of the underlying principle, it works without losses and thus with maximum efficiency. The inverter is easily controlled, has EMC friendly inherent di/dt and du/dt limitation, and can be built using low-cost standard semiconductors.

Background

Pulse width modulation inverters with ever higher switching frequencies and simultaneously increased efficiency are often being sought. Examples of such applications are electric drives in a variety of fields, such as ultra-light and high rpm drives in the aerospace industry and in hybrid cars, but also solar and wind power inverters as well as uninterruptible power supplies.

Problem

To meet these expectations, it is necessary to develop new switching topologies.  A known approach is to use multi-level inverters which nowadays represent the current technology.  A further approach is the „soft switching“ technology which seeks to eliminate switching losses via resonant, quasi-resonant, or passively switching losses reducing topologies resulting in higher switching frequencies and improved efficiencies.

Solution

At the Laboratory for Power Electronics of the HTWG Konstanz, these two approaches have been successfully combined in a simple manner and with unique characteristics.
The new Soft Switching Three Level Inverter (S3L-Inverter) is of striking simplicity and is therefore inexpensive. Because of the underlying principle, it works without losses and thus with maximum efficiency. The inverter is easily controlled, has EMC friendly inherent di/dt and du/dt limitation, and can be built using low-cost standard semiconductors.

Simplified diagram of SL3-inverter.
Simplified diagram of SL3-inverter.
Three phase prototype: 20 kVA, bis 1000 V_DC, 29 A_rms, Schaltfrequenz 18-32 kHz.

Advantages

  • Free of switching losses due to its design / thus maximum efficiency (one phase or three phases)
  • Low heat generation
  • Small cooling elements and fans
  • Very high switching frequencies possible
  • Smaller and lighter smoothing inductors and capacitors
  • Excellent EMC (Electromagnetic Compatibility) characteristics
  • di/dt and du/dt limiting
  • Integrated du/dt filter
  • Use of low-cost standard semiconductors / IGBT, GTO, IGCT

Application

  • Electric Drives
  • Solar Power Inverter
  • Wind Power Inverter
  • Uninterruptible Power Supplies (UPS)
  • HVDC
Exposé
Contact
Dipl.-Ing. Emmerich Somlo
TLB GmbH
Ettlinger Straße 25
76137 Karlsruhe | Germany
Phone +49 721-79004-0
somlo(at)tlb.de | www.tlb.de
Development Status
Prototype / TRL5
Patent Situation
CA 2789937C granted
CN 102804570B granted
DE 102010008426B4 granted
EP 2537239B1 granted,
FR, GB, CH validated
JP 2012-5395280 granted
KR 10-1366393 granted
US 8462524B2 granted
IN pending
Reference ID
09/113TLB
Service
The Technologie-Lizenz-Büro (TLB) GmbH is undertaking the commercialization of this technology and now offers companies the opportunity to obtain a license.