The Characteristics Of Limited Angle Reluctance Motor

Modern fighter aircraft flies very fast while the runway cannot be built as long as we want for its cost.So the drag parachute must be opened to make it slow down quickly when the fighter aircraft prepares to land.When fighter aircraft's speed is down to some certain value,the drag parachute should be released to recycle.The device is called drag parachute lock at home.In the early days,the hydraulic or pneumatic actuator was adopted widely.But its volume,mass and its bad reliability made it restricted.Compared to hydraulic or pneumatic actuator,the limited angle reluctance motor has small volume,light mass,high torque and good reliability.Limited angle reluctance motor has some similar aspects to single phase switched reluctance motor which follows the principle of minimum reluctance.It means magnetic lines of force are along the path of minimum reluctance.The magnetic lines of force twist which generates tangential force and electromagnetic torque.Unlike the general reluctance motor,both the stator teeth and rotor teeth are eight.Therefore its electromagnetic torque is 8 times as much as the single phase switch reluctance motor.The ordinary motors' winding is rolled along the radial direction on the stator teeth while the limited angle reluctance motor is along the axial direction on the coil support which is between stator and rotor.There is one limit adjustment bolt that is installed in the lateral of the stator to restrain the rotation angle.And there are 2 radial symmetric reset springs between two rotor slots.One side of springs is put on the rotor teeth,and the other side is put in designed slot in the stator teeth.The rotor's initial position is fixed by the reset springs and the bolts.This paper introduced a limited angle reluctance motor and described its major structure and operation principle.The major air gap permeance was analyzed by the method of given angle,and the electromagnet ic torque was induced based on principle of virtual work.By 3-D electromagnetic simulation,this paper got the surfaces of flux linkage inductance and torque for various currents and various rotor angles.The static characteristics were analyzed in detail.In order to obtain the dynamic performance,the mathematic model was deduced by nonlinear magnetic parameter method.The inverse function of magnetization curve and the torque surface were substituted into the equations.The equations were solved by adopting the forth-order Runge-Kutta method and finite element method.The curves of coil current,torque and rotor angle were obtained.And the related experiments were also carried out.The comparison of simulation and experiment proves solution's accuracy.