SD2M Turbo

The Booster

Standard converters in the higher power classes typically use the well-known technology of two-level pulse width modulation (PWM) with max. 8 kHz switching frequency. In most high-speed applications, this requires additional components such as LC filters or chokes to minimize the additional losses in the engine.

SIEB & MEYER frequency converters of series SD2M are specially designed for high-speed applications and use the innovative three-level technology – also called multi-level technology. This is of great advantage in these applications
because in most cases the SD2M converters do not require motor filter elements. This additional value is achieved by the three-level technology, as well as the PWM switching frequency of up to 16 kHz as standard. The combination leads to a considerably improved motor current quality, which significantly reduces the undesired rotor losses – by up to 90 %!



Function - Advantage - Benefit

Three-level technology

Function: The output stages of SD2M are based on a three-level technology and provide rotating field frequencies up to 2,000 Hz with switching frequencies of 16 kHz.
Advantage: Reduced motor losses combined with minimum efforts for motor filters and motor chokes as well as low interfering radiation and insulation stress.
Benefit: Low system costs over the whole product life cycle.


Function: The devices reach efficiencies of up to 98 %.
Advantage: The high efficiency of the devices ensures optimal system efficiencies and reduces cooling requirements.
Benefit: Maximum system output and lower environmental footprint due to lower energy consumption.

DC supply

Function: Active emergency braking and maintenance of voltage supply in case of power supply failure.
Advantage: No separate voltage supply for the magnetic bearings needed.
Benefit: Protection of the magnetic bearings in case of power failure as well as cost savings.


Motor currents by Comparison:

Two-level standard PWM SD2M three-level PWM


Good to Know

- Currently available power classes from 55 to 330 kW (75 to 440 HP), with up to 630 Arms rated current
- Liquid cooling as standard (water-based), air cooling on request
- NRTL/CSA certifications in progress for all versions
- Reducing the switching PWM amplitude by 50 % leads to very low insulation stress of the motor - even when using long motor cables  (see diagram below)
- Optional DC voltage supply for active magnetic bearings via internally fused terminals (intermediate DC circuit)
- Designed for 100 % load 24/7
- All power components are designed for 10 years continuous operation at nominal load
- Designed for worldwide 3-phase supply networks - also IT grids without grounding
- Efficient software drivemaster2 for parameterization and diagnosis
- Customized solutions can be realized
- 3C3 protective coating of the PCBs for operational reliability in aggressive environments

Isolation stress