Charging station

About 20% of CO2 gas emissions, which are the cause of global warming, come from traffic and transportation of which passenger cars are the largest source of emissions. The International Energy Agency announced that in order to achieve virtually zero CO2 emissions by 2050, "Internal combustion engine vehicles (ICE-powered vehicles) that run on fuel such as gasoline must be discontinued by 2035".

As a result, countries around the world have begun to tighten environmental regulations and have started to give preferential treatment to EVs, thereby rapidly increasing the spread of electric vehicles. China, in particular, is the world's largest market for electric vehicles, accounting for half of the world's total annual sales of electric vehicles.

Charging facilities are essential to meet the increasing demand for electric vehicles.
Just as there are petrol stations in cities, charging stations for electric vehicles are being built everywhere. In 2020, the number of EV charging infrastructures worldwide was 2.5 million in public infrastructure alone. The number is expected to reach nearly 10 million units by 2025. You may appreciate that these technologies are spreading rapidly.

Charging stations in cities use a DC charging method called quick charging. The quick charging station contains several switching power supply modules, which act like a heart that transmits the energy. This power supply module has a built-in PFC circuit.

The VIENNA PFC circuit has the following features: high power factor, high efficiency, and miniaturization. However, unless the characteristics of the current sensing method are fully applied, the features of VIENNA PFC circuitry cannot be utilized effectively.

・High power factor

If the zero current voltage is not accurate when the current is detected, the ON/OFF timing of the switch will shift. This causes THD (Total Harmonic Distortion) phase lag, and the power factor deteriorates.

→ AKM's current sensors have a small thermal response of zero current output voltage and are highly accurate, enabling the realization of a high powerfactor.　

・High efficiency

Energy loss occurs due to the heat generated when current flows through the current sensing unit.

→ AKM's current sensors have a low primary conductor resistance and a low heat generation, thus achieving high efficiency.

・Compact size

A large current sensing unit or many peripheral components will restrict miniaturization.

→ AKM's current sensors have a small surface area package and low profile, thereby enabling miniaturization. In addition, they have a high degree of mounting freedom, making it is easy to design a layout.

Table 1 below summarizes the features of "AKM's current sensors ICs," "Coreless current sensors from Other Companies," and "Shunt Resistor + high isolation Amplifier."