Application Auto Motive
OBC
EV On-Board Charger
Device that Supplies Power to OBC Lighting Equipment
An EV (Electric Vehicle) charger is a device that supplies power to electric vehicle batteries,
converting alternating current (AC) power from the power grid
to direct current (DC) power for battery charging.
Charging methods are broadly divided into slow charging through the vehicle's internal on-board charger,
and fast charging where the charging station's rectifier supplies power directly,
and can be utilized in various forms such as portable chargers or wireless charging
depending on convenience and needs.
Particularly recently, with India discontinuing internal combustion engine rickshaw sales and
converting entirely to electric rickshaws, sales volumes are rapidly increasing, and as the market
expands to Southeast Asia, demand for 3-wheels (auto rickshaw) chargers is also rapidly increasing.
On-Board Charger
On-Board Charger
An On-Board Charger (OBC) is a device built into electric vehicles (EV)
that converts alternating current (AC) power supplied from external sources
to direct current (DC) power for storage in the vehicle battery.
Used during slow charging, it converts AC power introduced through household plugs or
charging connectors to DC power suitable for EV batteries to enable charging.
AP SEMI has launched Super Junction MOSFETs with significantly improved TRR speed
through electron irradiation, offering a diverse lineup of high-power MOSFET and
RECTIFIER products suitable for fast switching speed drives.
01
Power Stage Topology
of OBC for EV
02
High Power Transistor
High Power TR
In LED converters (SMPS), power MOSFETs are used as power TRs
that convert input voltage to desired DC voltage and play a switching role
in supplying stable current and voltage to LEDs.
Since MOSFET characteristics significantly affect converter efficiency
and noise reduction performance, MOSFET characteristics must be
fully considered when designing LED lighting.
MOSFET Application 01
High-Efficiency Power Control
Since converter efficiency varies depending on MOSFET characteristics (e.g., on-resistance, switching speed),
select MOSFETs with high efficiency.
MOSFET Application 02
Heat Generation
OBC converters with high current generate heat, so consider appropriate heat dissipation measures
and select MOSFETs with low heat generation and good durability. Since heat dissipation capability
varies greatly depending on package type, check PD (Power Dissipation) before selection.
MOSFET Application 03
Voltage and Current
Select MOSFETs with sufficient specifications to handle
the input voltage and output current required for LED converters.
03
MOSFET Types and Characteristics
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01
Planar MOSFET
• Advantages
Simple structure, easy to manufacture with low cost, and has low noise characteristics
for good EMI performance.• Disadvantages
Large device ON resistance (RDS(on)), slow switching speed, increased device size
at the same voltage rating, and lower efficiency. -
02
Super Junction MOSFET
• Advantages
ON resistance (RDS(on)) and gate charge (Qg) are significantly lower than Planar MOSFETs,
improving efficiency with high-speed switching performance.• Disadvantages
Larger PN Junction area than Planar type results in higher reverse recovery current (irr)
during ON-OFF transitions, tends to have higher noise during high-speed switching, and is
more expensive due to highly integrated structure implementation. -
03
SiC MOSFET (Silicon Carbide)
• Advantages
Has wider bandgap than Si, delivering excellent performance even at high temperatures and voltages,
providing high efficiency with low conduction loss and high switching speed. Particularly suitable
for power conversion devices such as electric vehicle inverters and OBC (onboard chargers).• Disadvantages
Requires high-temperature processes above 2000℃, which is time-consuming and significantly
increases costs. High price and reliability issues (SiO2-SiC interface problems) result in low yields,
which can be a supply issue during commercialization. -
04
GaN MOSFET (Gallium Nitride)
• Advantages
Higher electron mobility than SiC enables very fast switching speeds, low conduction resistance
minimizes power loss and increases power density, reducing size and weight of compact power
supply devices while improving efficiency.• Disadvantages
Higher conductivity than SiC can limit possible power density, and yield and reliability
issues still exist.
MOSFET Lineup
04
Rectifier Diode
Rectifier Diode
Since the forward voltage of rectifier diodes in power converters is directly related to power loss,
high-efficiency power diodes must be used to increase efficiency.
By using diodes with short reverse recovery time
(TRR: Reverse Recovery Time)
to reduce switching losses, efficiency is increased and losses are minimized.
Standard Rectifier
Rectifier Diode with slow reverse recovery characteristics with TRR of 2-20 micro Sec.,
mainly used in primary rectification of adapters or power supplies or low-frequency circuits such as toys
Fast Recovery Rectifier
Rectifier Diode with TRR of 100~750 nano Sec., used in high-frequency (20~50Khz) circuits
Ultra Fast Recovery Rectifier
Rectifier Diode with TRR of 35~75 nano Sec., generates less heat than Fast Recovery Rectifier,
mainly used in high-voltage (400V~1000V), high-frequency (50Khz or higher) circuits
Ultra High Efficient Rectifier
High-speed rectifier Diode with TRR of 10~35 nano Sec., low resistance ($V_F$) reduces heat generation.
Used in low-voltage (up to 200~600V), high-frequency (50~200Khz) circuits
Schottky Barrier Rectifier
Very low internal resistance and fast operation speed, but low operating voltage and high leakage current.
Mainly used in high-frequency, high-current, low-voltage rectification
Ultra Low $V_F$ Schottky Rectifier
Schottky rectifier that uses trench process compared to general Schottky to significantly reduce forward voltage
SiC Schottky Diode
SiC Schottky diodes are Schottky diodes made using silicon carbide (SiC) semiconductors,
featuring low forward voltage drop, high-speed switching characteristics, excellent stability at high temperatures,
and virtually no reverse recovery current, enabling increased power efficiency and system simplification.
Particularly preferred products for high-power OBC and EV Chargers. However, the manufacturing process is
difficult and requires high-temperature operations, resulting in high costs, with prices about 10 times higher
than silicon Schottky diodes.
05
Photocoupler
Photo Coupler, Optocoupler, Isolator
A photocoupler is a device that transmits signals between the input and output circuits
in an electrically isolated state by activating the phototransistor (light-receiving section)
with light emitted when the internal LED turns on. When the electrical signal of the input circuit
flows current to the LED to generate light, this light passes through the phototransistor
to flow current to the output circuit, and through this,
signal transmission between the two circuits is achieved.
06
Shunt Regulator
Shunt Regulator
A shunt regulator is a device that regulates voltage to maintain stable output
despite input voltage fluctuations or load changes.
'Shunt' refers to a method of regulating voltage by connecting in parallel
to the load that conducts current, operating on the same principle as a shunt
to supply stabilized power at a specific voltage level.
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