Jürgen Steinke

Active Neutral-Point-Clamped Multilevel Converters

This paper proposes a multilevel power conversion concept based on the combination of neutral-point-clamped (NPC) and floating capacitor converters. In the proposed scheme, the voltage balancing across the floating capacitors is achieved by using a proper selection of redundant switching states, and the neutral-point voltage is controlled by the classical dc offset injection. Experimental results are illustrated in the paper to demonstrate the system operation

Switching frequency optimal PWM control of a three-level inverter

A pulse-width-modulation (PWM) method for the control of a three-level inverter is described. The switching frequency optimal-PWM method (SFO-PWM) works with a constant carrier frequency not synchronized with fundamental stator frequency. SFO-PWM gives an optimal utilization of the mean thyristor switching frequency permitted; therefore, PWM carrier frequency may be chosen to a value of two times the permitted mean thyristor switching frequency. The signal processing structure is simple. Many applications of three-level inverter work with a DC-link neutral point not stabilized from the power input converter. A neutral-point potential control is described, which is capable of stabilizing potential by varying the switching sequences of the three-level inverter itself. Results from computer simulation and practical experience show the good performance of SFO-PWM. >

Active-neutral-point-clamped (ANPC) multilevel converter technology

This paper proposes a multilevel power conversion concept based on the combination of neutral-point-clamped (NPC) and floating capacitor converters. In the proposed scheme, the voltage balancing across the floating capacitors is achieved by using a proper selection of redundant switching states, and the neutral-point voltage is controlled by the classical dc offset injection. Experimental results are illustrated in the paper to demonstrate the system operation

Comparison of single and two stage topologies for interface of BESS or fuel cell system using the ABB standard power electronics building blocks

The two most popular topologies used to interface the DC voltage sources such as battery energy storage systems (BESS), fuel cells with the AC network are the single and two stage topologies. In case of the single stage topology the BESS or the fuel cell system is directly connected to the dc link of a voltage source converter and the voltage source converter is interfaced to the low voltage grid with a transformer. A two-stage solution is realized using a DC-DC conversion stage followed by a DC-AC conversion stage. The DC-DC stage boosts the DC voltage so that the DC-AC stage can be directly interfaced to the low voltage grid. Detailed comparison of these topologies is carried out using battery voltage and the installed power as variables. The commercially available ABB standard Lopak PEBBs are used for comparison of the topologies. Both solutions are offered by ABB mainly depending on the dc voltage level of the BESS

Design comparison and control of medium voltage STATCOM with novel twin converter topology

A comparison of parallel and the proposed series or twin connected standard converters is presented for a 500 KVAr STATCOM. It is shown that the proposed topology is superior with respect to the filter size and maximum power output. Control issues specific to the twin topology are covered. A new way of controlling the converter under unbalance grid voltage conditions is proposed.