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System Overview
5
ZHCU404–December 2017
TIDUDF9 — http://www-s.ti.com/sc/techlit/TIDUDF9
版权 © 2017, Texas Instruments Incorporated
汽车类比例电磁阀电流传感器参考设计
• Reverse current protection
• Low I
SHUTDOWN
: 150 nA
• Supports 200-mA peak output
• 2% accuracy over temperature
• Available in fixed-output voltages: 1.2 V to 6.5 V
• Thermal shutdown and overcurrent protection
2.3 System Design Theory
Solenoids convert electrical current into mechanical motion—from a fundamental perspective, a solenoid
is simply a linear motor with a fixed range of travel. Solenoids are available in two basic types: on/off
solenoids and linear/ proportional solenoids. Solenoids of the on/off type convert electrical information into
mechanical information through the closing or opening of valves. Proportional solenoids convert electrical
signals into proportional mechanical force, which allows variance in armature position and force relative to
the current level. In applications such as transmission and fuel injection, proportional solenoids serve to
operate pistons and valves to accurately control fuel pressure or flow. Transmission applications require
accurate and smooth control of pressure to change gears seamlessly. The primary focus of this reference
design is on proportional solenoids and current monitoring.
2.3.1 Characteristics of Solenoid Coils
Electromechanical solenoids consist of an electromagnetically-inductive coil wound around a movable
steel or iron slug, which is known as the armature or plunger (see 图 2). The coil is shaped such that the
armature can be moved in and out of its center, altering the inductance of the coil as well as effectively
making it an electromagnet. The armature provides a mechanical force to activate the control mechanism,
for example, opening and closing of a valve or linear movement of the solenoid.