Abstract: An electromagnetic retarder apparatus with a built-in exciter having a retarder exciter inside thereof for generating braking torque by an eddy current produced in an eddy-current cylinder as a plurality of magnetic poles that are alternately magnetized to N and S poles by a field current caused to flow by a voltage generated in the exciter are caused to rotate in a relation to the eddy-current cylinder disposed at a location facing the magnetic poles; the eddy-current cylinder comprises a core formed by laminating a magnetic material, and short-circuiting method provided on the laminated core in the axial direction thereof for causing the generated eddy current to flow therein.

Abstract: A rotary-compressor control system for electric refrigerators using rotary compressors for cooling the inside of the refrigerators, in which a battery for feeding direct-current power, an inverter power section for converting direct-current (d-c) power from the battery into a low-voltage three-phase alternating-current (a-c) voltage, a low-voltage three-phase induction motor for driving the rotary compressor with the low-voltage three-phase a-c power obtained in the inverter power section, and a control circuit for controlling the inverter power section on the basis of a control command signal given from the outside, so that the rotary compressor is driven by the three-phase induction motor that operates with a low voltage of the order of battery voltage.