Multielement transformers for switched-mode power supplies: toroidal designs

The authors describe techniques for the design, construction and analysis of multielement transformers based on toroidal core transformer elements. It is shown that the multielement approach lends itself most readily to high frequency, low voltage DC-DC convertors. The design techniques for one multielement transformer are described in detail. Results for this, and a further three transformers, are evaluated in conventional rectangular wave convertors at 500 kHz. The authors show that the multielement transformer is a cheap, efficient design, which is ideally suited to this application. Its low leakage inductance means that voltage spikes produced at the turnoff transitions contain little energy and can be controlled by a simple zener diode clamp