Variable speed accelerator and method for controlling variable speed accelerator

A variable speed accelerator, comprising:

• an electric driving device which generates a rotational driving force;
• and
• a transmission device which changes the speed of the rotational driving force generated by the electric driving device and transmits the changed rotation driving force to a driving target, wherein
• the transmission device comprises
• a sun gear which rotates about an axis,
• a sun gear shaft which is fixed to the sun gear and extends in an axial direction around the axis,
• a planetary gear which meshes with the sun gear, revolves around the axis and rotates about its own center line,
• an internal gear which has a plurality of teeth aligned annularly around the axis and meshes with the planetary gear,
• a planetary gear carrier which has a planetary gear carrier shaft extending in the axial direction around the axis and supports the planetary gear to revolve around the axis and to be rotatable around a center line of the planetary gear itself, and
• an internal gear carrier which has an internal gear carrier shaft extending in the axial direction around the axis and supports the internal gear to be rotatable about the axis,
• the sun gear shaft forms an output shaft connected to the driving target, the internal gear carrier shaft forms a constant-speed input shaft, and the planetary gear carrier shaft forms a variable-speed input shaft,
• the electric driving device comprises
• a constant-speed motor having a constant-speed rotor which rotates a constant-speed input shaft of the transmission device in a second direction, and
• a variable-speed motor which has a variable-speed rotor connected to the variable-speed input shaft of the transmission device and which rotates the output shaft at a maximum rotation rate by rotating the variable-speed rotor at a maximum rotation rate in a first direction opposite to the second direction, and
• the variable speed accelerator further comprises
• a rotation rate controller which issues a speed instruction to the variable-speed motor and controls a rotation rate of the variable-speed motor,
• a torque measuring device which measures a torque of the variable-speed motor, and
• a control device which holds an instruction value of the speed instruction or reduces a rate of change of the instruction value of the speed instruction to below a rate of change of the instruction value of the speed instruction at that time when a torque direction of the variable-speed motor is the second direction.