Abstract: A control system of a power converter includes a plurality of carrier wave generating units which are respectively provided for a plurality of power converters connected between a plurality of DC power supplies and a common AC power supply and which are configured to respectively generate carrier waves on the basis of an AC voltage of the AC power supply. The control system of the power converter can thereby synchronize carrier phases of a plurality of power converters.

Abstract: A magnetic recording medium is disclosed, which has a magnetic layer containing a hexagonal ferrite powder dispersed in a resin binder, the magnetic layer being formed on a nonmagnetic supporting substrate, wherein the hexagonal ferrite powder is a compound represented by the following chemical formulaAO.2 (M.sup.1 0).Fe.sub.16-x M.sup.2.sub.x 0.sub.24where A is at least one element selected from the group consisting of Ba, Sr, Ca, and Pb; M.sup.1 is at least one element selected from the group consisting of Zn, Ni and Co; M.sup.2 is one combination selected from the group consisting of a combination of two elements of Co and Ti, a combination of two elements of Ti and Zn, and a combination of three elements of Co, Ti and Zn; and x designates a number in the range from 0.6 to 3.0, the hexagonal ferrite powder having an average diameter/thickness ratio in the range from 2.0 to 5.

Abstract: Disclosed is a magnetic recording medium comprised of a substrate and a layer of magnetic powder coated on a surface of the substrate, characterized in that the magnetic powder is hexagonal crystals having single domain crystalline magnetic anisotropy, particle sizes of 0.01 to 0.3 .mu.m, particle size/thickness ratios of 2.3 to 15 and the tapping packing rate of said magnetic powder is 15% or more.