SLUAAS4 January 2024 LM5155-Q1 , LM51551-Q1 , LM5156-Q1 , LM51561-Q1 , LM51561H-Q1 , LM5156H-Q1 , LM5157-Q1 , LM51571-Q1 , LM5158-Q1 , LM51581-Q1 , UCC28700-Q1 , UCC28730-Q1 , UCC28740-Q1 , UCC28781-Q1 , UCC28C50-Q1 , UCC28C51-Q1 , UCC28C52-Q1 , UCC28C53-Q1 , UCC28C54-Q1 , UCC28C55-Q1 , UCC28C56H-Q1 , UCC28C56L-Q1 , UCC28C57H-Q1 , UCC28C57L-Q1 , UCC28C58-Q1 , UCC28C59-Q1
The automotive industry is transitioning from combustion engines to electric vehicles (EV) and hybrid electric vehicles (HEV). One of the key parts of an EV and HEV system is a Traction Inverter. The traction inverter takes the DC input power from the high-voltage (HV) battery and provides the controlled AC power to the e-motor. Along with power Switches and gate drivers, isolated bias power supply is a major portion in the traction inverter circuit. One of the main functions of the isolated bias supply is to provide the required power to the gate drivers. There are several possible architectures for the isolated bias power supply. These architectures also influence the choice of the topologies and associated devices.
Isolated bias supply provides power to the different gate-driver circuits in HEVs and EVs. There are different topologies to design an isolated bias power supply. The most commonly used topologies are flyback, push-pull, LLC-resonant, and integrated transformer modules. Each topology provides specific advantages but at the same time has trade-offs and challenges. The choice of the topology depends largely on the overall architecture of the isolated bias power supply.
Isolated bias power supplies take power either from the low-voltage (LV) battery or from the high-voltage battery of the HEV, EV. Based on the power source, the isolated bias power supplies can be divided in two groups: low-voltage isolated bias power supplies and high-voltage isolated bias power supplies. The isolated bias supply circuit can be directly connected to the battery or connected to the battery using the pre-regulators. The pre-regulators are needed depending on the wide input voltage range capability of the device. Although, LV batteries are common as a power source for isolated bias power supplies, often both LV and HV batteries are used to provide redundancy in the system. A redundant power supply can lead to achieve higher functional safety of overall system. Figure 1-1 shows a traction inverter block diagram.