Enhanced electric power steering system design, more reliable and more energy-efficient!
Latest update time：2020-05-29
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Electric Power Steering
(EPS)
systems assist the driver in steering the vehicle, improving directional control, steering feel and safety. They also reduce engine load, thereby improving fuel efficiency.
Because of these many advantages, EPS systems are becoming more and more popular in today's automobiles. These systems typically use a 3-phase brushless DC
(BLDC)
motor instead of the hydraulic actuation mechanism, but on some lower-cost systems, a brushed DC motor can be used.
The EPS system saves energy and consumes power only when steering force is needed to drive the vehicle. For example, in a 2000cc mid-range car, using an EPS system can achieve a fuel saving of 0.8 liters per 100 kilometers.
EPS system diagram
The EPS system uses an electric motor to generate the required power. The power is transmitted to the steering rack or steering column through an electrified electronic control unit
(ECU)
, which contains a power inverter composed of semiconductor switches. The ECU usually uses a six-switch inverter for BLDC motors and a four-switch inverter for brushed DC motors.
It is becoming more common for
EPS systems to combine the motor, power steering, and ECU into a single component
called a "powerpack."
EPS system block diagram
With the recent popularity of autonomous driving technology, EPS systems are evolving to meet the stringent safety requirements of Automotive Safety Integrity Level-D
(ASIL-D)
, which is the primary safety goal of EPS systems. To achieve the ASIL-D safety goal, some customers are using 6-phase BLDC motors or dual 3-phase BLDC motors. These systems require advanced ECUs that can control these motors while maintaining a compact system size.
ON Semiconductor provides most of the key components used in these EPS systems:
For ECU interface I/O:
Provides a full range
of transceivers or system basis chips
(SBCs)
, including FlexRay, LIN and CAN transceivers
For power management:
Providing power protection ICs,
voltage regulators
,
voltage supervisors
and gate driver ICs.
For signal conditioning:
Provides cost-effective
operational amplifiers
,
current sensing
,
thermal management
ICs and
EEPROM
.
For flexible power stage and phase disconnection (motor lead connection) :
Provide
automotive grade power MOSFET
For compact power stages:
Provide the latest
APM19
NXV04V120DB1
automotive power module
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