Sound coil motor principle
time£º2012/11/20 click£º14011
Voice Co Il Octato R is a special type of direct drive motor. Simple structure, small size, high speed,
High acceleration, fast response and other characteristics. The principle of this is that the pass coil(conductor) is placed in a magnetic field to produce force, the size of the force, and the applied line.
The current on the circle is in proportion. Based on this principle, ring motor motion can be straight line or arc.
In recent years, with the improvement of the performance requirements of high speed and high precision positioning system and the rapid development of the sound coil motor technology, the sound coil motor is not only
It is widely used in precision positioning systems such as disks and laser record positioning[ 1] It is also widely used in many different forms of high acceleration and high frequency excitation.
Pan-application. For example, the positioning of lenses in optical systems; Multi-coordinate positioning platform for mechanical tools; Precision Electron Pipe and Vacuum Control in Medical Devices
System; In flexible robots, in order to make the end actuator position quickly and accurately, the sound coil motor can also be used to effectively suppress vibration[ 2] ..
However, there are not many literatures about the detailed technical principles of the acoustic motor. Therefore, this paper will systematically discuss the basic principles of the acoustic motor and explain it.
The method of selection and application are described.
Basic Principles of Sound Loop Motor
1. Magnetism principles
The working principle of the coil motor is based on the principle of ampere force, that is, when the electrified conductor is placed in a magnetic field, the force F is generated. The size of the force depends on the strength of the magnetic field B, the current I, and the direction of the magnetic field and the current(see Figure 1). If the N wire with a total length of L is placed in a magnetic field, the force acting on the wire can be expressed as F = kBL IN, in formula(1) K is the constant. As can be seen from Figure 1, The direction of the force is a function of the direction of the current and the magnetic field vector. If the magnetic field and wire length are constant, the resulting force is proportional to the input current. In the simple structure of a coil motor, a linear coil motor is a tubular coil winding located in a radial electromagnetic field(see Figure 2). Inside the ferromagnetic cylinder is a magnetic field produced by permanent magnets. This arrangement allows the magnet attached to the coil to have the same polarity. The inner core of ferromagnetic material is arranged on the axial centerline of the line loop and connected to one end of the magnet to form a magnetic loop. When the coil is energized, it is subjected to a magnetic field, which produces force along the axis between the coil and the magnet. The direction of the polar determining force of the voltage at both ends of the wire loop. The generator of the electric force of the rotating sound ring
2. The principle of electronics
Sound coil motor is a single phase bipolar device. The voltage applied to the coil generates a current in the coil, which in turn generates a force proportional to the current on the coil, allowing the coil to move axially in the air gap. The direction of motion is determined by the current direction of the coil. When the coil moves in the magnetic field, a voltage(ie induced electromotive force) proportional to the coil motion speed, magnetic field strength, and wire length is generated. The power supply of the drive coil motor must provide enough current to meet the needs of the output force, and overcome the induced electromotive force generated by the coil at the peak motion speed, and the leakage induced pressure drop through the coil.
3. Mechanical system principle
Sound-coil motors are often sold as a component of magnets and coils. The small air gap between the coil and the magnet is usually(0. 5 ~ 5 mm, this gap can be increased as required, but the range of movement allowed by the boot system needs to be determined, while avoiding friction or collision between the coil and the magnet. In most cases, the moving load is connected to the coil, that is, the dynamic ring structure. The advantage is that the fixed magnet system can be relatively large, so a strong magnetic field can be obtained; The disadvantage is that the coil transmission line is in motion and is prone to fault. At the same time, thermal contact between moving parts and environment is very bad. When the load is particularly sensitive to heat, the load can be connected to the magnet, IE, the fixed sound structure. The heat dissipation of the structure coil is no longer a big problem, and the peak current allowed by the coil is large, but in order to reduce the mass of the moving part, Small magnets are used. Therefore, the magnetic field is weak[ 3] ..
The linear coil motor can drive directly, with no recoil and no energy loss. The recommended guide is a straight line bearing or liner combined with a hardened steel shaft. The axisymmetric liner can be assembled into an integral part. It is important to maintain low friction in the boot system so as not to reduce the smooth response characteristics of the motor.
Linear motor