Designing for Efficiency
2 www.cadence.com
1. Introduction
In practical power electronics systems, efficiency is not an isolated metric. It determines how much power is dissipated inter-
nally as heat. Any power not delivered to the load appears as internal loss:
Even small efficiency improvements significantly reduce thermal stress. Lower internal loss decreases junction temperature,
relaxes cooling requirements, and improves long-term reliability of semiconductors and passive components.
From a system perspective, higher efficiency enables:
f
Reduced cooling infrastructure
f
Smaller mechanical form factor
f
Higher power density
f
Improved reliability margins
f
Lower lifetime operating energy cost
Wide bandgap SiC devices reduce switching and commutation losses, but their full benefit emerges only when evaluated in a
complete converter. Simulation provides a controlled environment to study these interactions before hardware is built.
All analysis in this application note is based on the reference converter shown in Figure 1. This schematic provides the archi-
tectural context for the loss mechanisms, waveforms, and efficiency measurements discussed in the following sections.
2. Push-Pull Converter Topology Overview
The reference design is an isolated push-pull converter driven by a UC1846 PWM controller. This topology is widely used in
medium-power supplies because it efficiently utilizes transformer core material and naturally resets magnetic flux each cycle
Figure 1: Reference push-pull DC-DC converter schematic simulated in this application note. The UC1846 PWM controller drives a push-pull
switching stage that excites transformer XFMRAUX, followed by secondary rectification and output filtering. All efficiency and loss
measurements are derived from transient simulation of this circuit..
