Improved output power capability of Hybrid Excited Flux-Switching DC-Alternators: Analysis and experiments

Abstract

In this paper, performance evaluation of a Hybrid Excited Flux-Switching Permanent Magnet (HEFSPM) DC generator is presented. The application principle of a DC controlled bus over a wide speed range will be firstly detailed. The main idea of such machine topology is that all the active parts are located in the stator so that the air-gap flux can be easily controlled with no need of brushes. This scheme uses a low-cost diode bridge rectifier directly connected to the HEFSPM Generator to transfer active power to the battery and the load. By means of Finite Element Analysis (FEA), a simple methodology was developed to determine the power capability of the proposed structure. The influence of the BH magnetization curve will be also explored. Experimental results on a 3kW -24-Slot 20-Pole HEFSPM DC Generator were performed and compared to the previous analysis. This relative low time-consuming approach could be useful to predict, with good agreement, the power capability of hybrid excited generator. Finally, an original compensation technique to improve performance of the generator is discussed. An analytical approach to predict the impact of series capacitor on the power capability is proposed and then validated by experiments. It is demonstrated that low speed power capability can be enhanced by 2.5 times using this technique.

Investigation of a New Topology of Hybrid-Excited Flux-Switching Machine with Static Global Winding: Experiments and Modeling

“…The short-circuit current density is determined in order to assess the potential of such a structure when in generator mode connected to a diode bridge rectifier (DBR). The maximum output power when the machine is connected to a DBR can actually be defined by the following formula [19]:…”

Performances of a hybrid excited flux-switching DC-alternator: Analysis and experiments

“…The rotor is composed by 20 salient poles, and has neither windings nor permanent magnets. The structure investigated in this paper was already reported in [15] [16]. The prototype and specifications are shown in Fig.1 and Tab.II.…”

“…For experiment, the HEFSPM is associated with a diode-bridge rectifier. [16][18] The scheme of the experimental bench is given in Fig.2 As prime mover of HEFSPM generator, an induction motor of 5.5kW is employed. The DBR is connected on the same DC-bus voltage feeding the 3-phase inverter controlling the induction motor.…”

“…In order to explore the output power, the DC-bus is replaced by a shortcircuit in experimental bench. Relations between output power and short-circuit current are explored in [16]. Two methods are used to calculate the short-circuit current density.…”