Magnetically Integrated Structure for Transformer-Type Controllable Reactors: Magnetic Circuit and Circuit Analysis

In order to meet the high impedance and weak coupling design requirements of controllable reactors of transformer type (CRT), a practical CRT body structure is proposed, based on magnetic integration technology. First, the paper presents the new structure. By using a leakage magnet core between the work and control windings, the proposed structure integrates the transformer and the current-limiting inductance together, thus forming a basic, independent, high-impedance unit. Several of these basic independent units are then combined in parallel to form the CRT body, which meets the weak coupling design requirement. Second, the distributions of both the main and leakage magnetic fluxes are analyzed in detail under different working conditions, by establishing the equivalent magnetic circuit and equivalent circuit models. The current calculation formula is deduced, and the relationship between the current and flux distribution is revealed.Based on this analysis, a single phase CRT whose control windings' rated currents are 10A, 15A, and 20A respectively is simulated and calculated. The obtained simulation results show that, when the control windings are short-circuited in sequence, the work winding currents are 9.997 A, 24.540 A, and 43.900 A, which are fundamentally the rated current values. the short-circuit currents of the operating control windings do not affect the other control windings operating. The proposed CRT structure can meet the high impedance and weak coupling design requirements.