*2.2.2.1. DC-DC converter*

Owing to the advent of intelligent vehicle systems, the demand of DC power for automotive electronic equipment is continuously increasing. A DC-DC converter possesses the function of converting the input DC voltage to another output DC voltage with different levels. A high conversion efficiency can be usually guaranteed [15]. Normally, DC-DC converters are switching regulators with operations at high frequency. MOSFETs and IGBTs are used as switches. The size of the MOSFETs or IGBTs is drastically reduced at high-frequency operation. The switches are turned ON and OFF by pulse-width modulation (PWM) technique.

The applications of DC-DC converters have been implemented in AFVs. Bidirectional DC-DC converters are applied for battery charging, regenerative braking, and backup power. Unidir‐ ectional DC-DC converters are also used in DC motor drives and electric traction.

A bidirectional DC-DC converter as seen in Figure 2 can be divided into three main blocks. The primary side (low-voltage side) usually consists of a buck or boost-type converter and the secondary side is usually half or full-bridge arrangement.

**Figure 2.** Full-bridge bidirectional DC-DC converter
