Inside STABL technology

Working Principle of our Inverter Simply Explained

Our STABL inverter technology enables loss-free balancing.

Working principle of conventional inverters with sinusoidal voltage, i.e. pulse width modulation

Working principle Conventional inverters

Normal battery inverters switch the high voltage of the power storage unit on and off at different intervals. This process is called pulse width modulation. The resulting voltage must be smoothed by a so-called mains filter so that it complies with the standards and requirements of the power grid. This costs efficiency and causes losses.

Working principle of modular multilevel inverters with flexible voltage output

Functional principle of STABL inverters

Our approach is known in the scientific community as a "modular multilevel inverter" and is widely used in high-voltage direct current transmission. We were the first company to optimize it for battery storage systems. The sine wave voltage is simulated by connecting the individual battery modules in series one after the other. The step voltage generated in this way is much more similar to the desired grid voltage than with conventional inverters for battery storage systems. This means that the mains filter can be smaller and losses are minimized.

Inverter technology

Proving our Inverter technology Works

Comparison of the efficiency characteristics of STABL modular multilevel inverters with conventional inverters

Conversion efficiency of up to 99.4 % efficiency

As part of a master’s thesis at the Technical University of Munich, the efficiency of our modular design was tested and compared with that of a conventional inverter. The results show a very high efficiency of our approach of up to 99.4 %. Compared to a conventional central inverter of a battery storage system, higher efficiencies were achieved across the entire power range, which is mainly due to the significantly lower switching voltages and frequencies. Instead of switching the entire voltage of a high-voltage pack, STABL technology generates the AC voltage by dynamically connecting and disconnecting low-voltage battery modules. Another advantage of STABL technology is the significantly lower total harmonic distortion (THD) before filtering. The values achieved enable the use of smaller, more cost-effective and more efficient filters.

The high conversion efficiency has an effect on the efficiency of the entire storage system and thus lowers the levelized cost of energy (LCOE), which enables an earlier and higher return on investment.

Technology of the multi-level inverters from STABL in a rack of the storage container.

Deep battery analytics thanks to modular multi-level inverters

Our STABL modules can measure battery modules during operation and automatically store the data in the STABL cloud. We generate high-precision data on condition, temperature, current and voltage in real time, helping battery manufacturers to monitor the performance of their cells. For example, battery manufacturers can detect faults in certain batches or find out which external circumstances have which effects on the cells.

Insurers also benefit from this data, as it enables reliable risk assessment and thus enables insurers and reinsurers to design attractive insurance policies.

Our inverter technology can be used for a wide range of applications and can output any conceivable output voltage - including DC voltage. The software-defined function in particular makes it possible to tap into different markets with one and the same hardware.