46results about How to "Reduce dynamic loss" patented technology

The invention provides a reactive power control method and device of a four-quadrant current source converter. The reactive power control method comprises the steps of obtaining a reference current imaginary part value and an actual current imaginary part value at an AC (Alternating Current) side of the four-quadrant current source converter; obtaining a triggering angle control quantity based on the difference value between the reference current imaginary part value and the actual current imaginary part value; and controlling the reactive power of the four-quadrant current source converter by adjusting the triggering angle control quantity. The reactive power control method and device of the four-quadrant current source converter solve the problems in the prior art that relatively big switching loss is resulted when a PWM control technology is adopted for reactive power control of the current source converter and relatively great stress may be generated for a switch device by the current source type converter when the current is cut off at a high frequency.

The invention discloses a heterospolar type permanent magnet bias mixed radial magnetic bearing. The heterospolar type permanent magnet bias mixed radial magnetic bearing comprises a stator assembly and a rotor assembly. The rotor assembly comprises a rotary shaft and a rotor iron core arranged outside the rotary shaft. The stator assembly comprises auxiliary magnetic poles, a stator iron core, permanent magnets and excitation coils. Stator magnetic poles with the number of the multiple of four are distributed on the inner surface of the stator iron core evenly at intervals in the circumferential direction. One auxiliary magnetic pole is arranged between every two adjacent stator magnetic poles. One permanent magnet is embedded between each stator magnetic pole and the adjacent auxiliary magnetic pole. The magnetizing directions of every two adjacent permanent magnets are opposite. One set of excitation coils are arranged in a groove between every two adjacent stator magnetic poles. Work air gaps are arranged between the surfaces, toward the axes, of the stator magnetic poles and the auxiliary magnetic poles, and the outer surface of the rotor iron core. An electrical excitation magnetic path of the magnetic bearing does not pass the permanent magnets, additional air gaps do not exist, the auxiliary magnetic poles effectively solve the problem that the stator yoke thickness is large, the stator outer diameter can be reduced, and the space utilization ratio is increased.