Best-in-class superjunction MOSFETs and cost-competitive IGBTs for EV chargers

Plug-in hybrid/electric vehicles (xEV) contain a high-voltage battery subsystem that can be charged using a built-in onboard charger (OBC) or an external charging station. Charging (application) requires high voltage, high current and high performance in a high temperature environment. Developing high-efficiency, high-performance, and protection-rich charging stations is essential to achieve longer mileage with the shortest possible charging time. Commonly used semiconductor devices are IGBT, super junction MOSFET and silicon carbide (SiC). ON Semiconductor provides complete system solutions for electric vehicle OBC and DC charging stations, including super junction MOSFET, IGBT, gate driver, silicon carbide (SiC) devices, voltage detection, control products and even power modules certified by AEC automotive regulations, supporting designers to optimize performance and accelerate development cycles. This article will mainly introduce super junction MOSFET and cost-effective IGBT solutions for electric vehicle DC charging stations.

Electric vehicle charging levels and range

Charging piles are classified by charging capacity to handle different use case scenarios. Level 1 charging piles are 120 V AC charging piles with an output of 15 A or 20 A, which add about 4 to 6 miles of range for every hour of charging. Level 2 charging power has four power levels of 3.3 kW, 6.6 kW, 9.6 kW, and 19.2 kW, which are suitable for 240 V AC power outlets with output currents of 20 A, 20 A, 50 A, and 100 A respectively. DC fast charging (DCFC) piles have an input voltage of 440 V or 480 V, can charge to about 80% in 30 minutes, and are used for public charging piles. According to China's "one car, one pile" plan, the total number of electric vehicle charging piles will reach 4.8 million in 2020, and at least 2 million of the total installed capacity of 4.5 million electric vehicle charging projects will be high-power DC charging piles, and other countries will also increase electric vehicle charging piles after 2020. ON Semiconductor mainly provides DCFC solutions.

Figure 1: Electric vehicle charging levels and range

Electric vehicle charging pile power module system trends

1. Increase output power to save charging time

Charging piles will develop from the current mainstream 60 kW and 90 kW to 150 kW and 240 kW in the future. Correspondingly, the charging pile power modules will be increased from the current 15 kW, 20 kW and 30 kW to 40 kW, 50 kW and 60 kW in the future to shorten the time to fully charge.

2. Increase power density to save space

This can be achieved by increasing the switching frequency Fsw to reduce passive components and reducing losses to reduce heat sinks.

3. Improve energy efficiency to save energy

ON Semiconductor is positioned to increase full load efficiency from 95% today to over 96%, surpassing energy efficiency regulations.

4. Improve system reliability

This requires extending the service life of electrolytic capacitors and ensuring high reliability in outdoor installations such as in dusty, humid, hot, and cold areas.

Advantages and usage trends of super junction MOSFET

Energy conservation and emission reduction trends, such as the shift to zero-emission electric vehicles, are driving demand for medium and high voltage MOSFETs. Planar MOSFETs have large on-resistance Rds(on) and losses. And since the breakdown voltage is proportional to the area, a larger area of ​​doping is required to achieve a higher breakdown voltage. Superjunction MOSFETs can significantly reduce the on-resistance Rds(on) and gate charge Qg. Due to charge balance, the area of ​​superjunction MOSFETs is twice as large under the same doping, so the breakdown voltage is also twice as large, and the breakdown voltage is approximately linearly related to the on-resistance, which significantly reduces conduction losses and switching losses. Superjunction MOSFETs are often used in high-end applications due to their high energy efficiency and power density in fast switching applications.

Electric vehicle charging pile architecture and ON Semiconductor's 3rd generation superjunction MOSFET solution

For example, a 210 kW electric vehicle charging point consists of 14 15 kW modules. Each 15 kW battery charger module is powered by a 3-phase AC 380 V input. After 3-phase Vienna power factor correction (PFC), the voltage is increased to 800 V DC voltage, and then outputs 250 V to 750 V DC voltage through a high-voltage DC-DC.

Figure 2: Electric vehicle charging station architecture

Among them, the 3-phase Vienna PFC can use the EASY Drive/FAST series of ON Semiconductor's third-generation super junction MOSFET (SUPERFET III), and the multi-level LLC can use the SUPERFET III fast recovery (FRFET) series. The EASY Drive series can internally adjust the gate resistance Rg and parasitic capacitance, has extremely low EMI and voltage spikes, and is suitable for hard/soft switching. The FAST series has reduced gate charge Qg and output capacitor storage energy Eoss, low switching loss, high energy efficiency, and is suitable for hard switching topologies. The FRFET series integrates a highly optimized fast recovery diode with ultra-low Qrr and Trr, minimizes switching losses and improves system-level reliability, and is suitable for soft/hard switching topologies.

Figure 3: Recommended ON Semiconductor SUPERFET III solution for electric vehicle charging piles

SUPERFET III FRFET series features ultra-low Qrr and Trr

By comparing ON Semiconductor's SUPERFET III FRFET series and Easy Drive series under the same operating conditions, it was found that the Qrr and Irr of the FRFET series were 90% and 73% lower than those of the Easy Drive series, respectively.

ON Semiconductor's SUPERFET III FRFET Outperforms Competitors

Under the same operating conditions, the gate charge Qg, Trr, Irr, Qrr and Eoss of ON Semiconductor's SUPERFET III FRFET are measured to be lower than those of competitors to varying degrees, ranging from 8% to 47%, and have lower on-resistance Rds(on), turn-off loss and best-in-class diode performance, thus providing higher system energy efficiency.

Avoiding Output Short-Circuit Faults Using SUPERFET III FRFETs

Ordinary MOSFETs are prone to output short-circuit failures in LLC topologies, but ON Semiconductor's SUPERFET III FRFET can avoid output short-circuit failures by optimizing parameters such as gate charge Qg, allowing the device to operate normally.

Improve system efficiency with HF version of SUPERFET III FRFET

The F version of ON Semiconductor SUPERFET III FRFET is a slow switch when turned off, so it has low peak Vds and low dv/dt, and the advantage is better EMI performance. The HF version is a fast switch when turned off, so it has lower switching loss and lower Ross, which can provide higher system energy efficiency.

Cost-effective IGBT solution for electric vehicle charging piles

Compared with super junction solutions, IGBT can provide a cost-effective solution for electric vehicle charging piles. ON Semiconductor provides industry-leading field stop IGBT technology. Its latest fourth-generation field stop (FS4) IGBT has the lowest conduction loss, turn-on loss, turn-off loss, body diode loss and smaller voltage spikes in its class. The recommended FS4 IGBT and rectifier solutions for electric vehicle charging piles are shown in the following table.

Figure 4: Cost-effective IGBT and rectification solution for electric vehicle charging piles

SiC and Intelligent Power Modules (IPM)

In addition, ON Semiconductor also provides 650 V and 1200 V  SiC diodes , 1200 V  SiC MOSFETs , and compact IPMs to achieve higher energy efficiency, power density and reliability.

Summarize

With its expertise in power devices and packaging technology, ON Semiconductor provides energy-efficient and innovative semiconductor solutions for electric vehicle charging applications, including best-in-class super junction MOSFETs, cost-effective IGBT and diode solutions, SiC-based solutions and IPM, which help achieve higher performance, energy efficiency and lower losses, and are an excellent choice for power modules such as DC-DC and PFC for electric vehicle charging piles.

About ON Semiconductor

ON Semiconductor (NASDAQ: ON ) is committed to driving innovations in energy-efficient electronics, enabling customers to reduce global energy use. ON Semiconductor is a leading supplier of semiconductor-based solutions, offering a comprehensive lineup of energy-efficient power management, analog, sensors, logic, timing, interconnect, discrete, system-on-chip (SoC) and custom devices. The company's products help engineers solve their unique design challenges in automotive, communications, computer, consumer electronics, industrial, medical, aerospace and defense applications . The company operates a sensitive, reliable, world-class supply chain and quality program, a strong compliance and ethics program, and a business network including manufacturing plants, sales offices and design centers in key markets in North America, Europe and Asia Pacific.