The paper presents a topological overview of hybrid powertrains for battery-powered vehicles reinforced by range extenders. First, tradeoffs of employing high energy versus high power battery are revealed. Then, different topologies of battery-ultracapacitor hybrids are discussed, highlighting pros and cons of each configuration. The superiority of fully active hybrids is indicated, obtained at the expense of increase of power electronic circuitry, control effort, and efficiency. The second part of the paper focuses on two types of range extenders: renewable energy and fuel-based units. The operation strategy is shown to be different for each range extender type. The renewable-energy-based range extender should be operated employing either passive or active maximum power point tracking strategy and hence not be involved in the powertrain energy balancing. It is shown that such a strategy allows the rest of system to perceive the renewable energy range extender (RERE) as a part of the load and act accordingly. Solar array is given as an example of a RERE and the possible connection topologies are discussed. On the other hand, the fuel-based range extender (FBRE) should be operated near the lowest specific fuel consumption point employing maximum efficiency point tracking strategy. Fuel cells and internal combustion engines are specified as examples of FBREs. The complete powertrain is shown to resemble a dc microgrid with source, storage, and load units connected through power management circuitry to a common dc link.

Stationary reference frame proportional-resonant (PR) controllers have recently became a viable alternative to rotation reference frame proportional-integrative compensators in ac applications because of their ability of achieving zero steady-state error without the need for computational-intensive reference frame transformations. While extensive efforts have been put into performance comparison of the two control schemes, design of PR controllers according to desired closed-loop time-domain transient performance was barely investigated. This letter proposes a method for deriving PR controller structure and coefficients according to desired transient behavior of ac signal amplitude, applied to typical power converter current loop. The method is based on the fact that if ac signal envelope is perceived as dc signal, its transient behavior may be easily shaped utilizing well-known approaches employed in dc systems loop shaping while keeping zero phase tracking error at all times. On the other hand, while desired transient performance is easily achieved, the relation between crossover frequency and transient processes time constant is not as straightforward as in dc systems. The validity of the presented theoretical analysis is evaluated by simulations.