Trans-synchronous motor apparatus and method

Claim 3

A method as claimed in claim 1 and in which the applied a.c. power is single phase.

Claim 4

A method as claimed in claim 2 and in which P=6 and the fractional speed is 400 rpm.

Claim 5

A method as claimed in claim 1 and in which said switching is effected at the zero-axis crossings of said half cycles.

Claim 6

A method as claimed in claim 4 and in which the motor is switched on and off at said zero-axis crossings.

Claim 7

A method as claimed in claim 1 and in which selected half cycles respectively applied to corresponding poles are interchanged to reverse the direction of motor operation.

Claim 8

A method as claimed in claim 1 and in which said magnetic poles are de-energized and said power is switched over to a high speed winding when the fractional speed motor is running in the correct direction at its full fractional speed, with the switch-over effected at a zero-axis crossing of the said half cycles.

Claim 9

Trans-synchronous motor apparatus for generating speeds in revolutions per minute that are a fraction (1/n) of 120 f/P, where f is the line frequency in cycles per second and P is an even number of magnetic poles, said apparatus having, in combination, three geometrically spaced and connected magnetic-pole windings, each having a switch for controlling the energizing of the corresponding winding from a power source; means for producing pulses corresponding to the zero axis crossing of the power; means responsive to the pulse-producing means for selecting for each of said windings a full half cycle of the power energy every n half cycles, wherein n corresponds to the denominator of the desired fraction of 120 f/P, with the selected half cycles for each winding being symmetrically time-staggered with respect to those of the other windings; and means responsive to the selecting means for controlling the winding switches to energize each winding at different times from other windings during corresponding selected half cycles to produce an effective excitation field that generates a motor speed of said fraction of 120 f/P.

Claim 10

Trans-synchronous motor apparatus for generating speeds in revolutions per minute that are a fraction (1/n) of 120 f/P, where f is the line frequency in cycles per second and P is an even number of magnetic poles, said apparatus having, in combination, three geometrically spaced and connected magnetic-pole windings, each having a switch for controlling the energizing of the corresponding winding from a power source; means for producing pulses corresponding to the zero axis crossing of the power; means responsive to the pulse-producing means for selecting for each of said windings a full half cycle of the power energy every n half cycles, wherein n corresponds to the denominator of the desired fraction of 120 f/P, with the selected half cycles for each winding being symmetrically time-staggered with respect to those of the other windings; and means responsive to the selecting means for controlling the winding switches to energize each winding at different times from other windings during corresponding selected half cycles to produce an effective excitation field that generates a motor speed of said fraction of 120 f/P.

Claim 11

Trans-synchronous motor apparatus as claimed in claim 8 and in which the applied power is single phase.

Claim 12

Trans-synchronous motor apparatus as claimed in claim 8 and in which the three windings provide six magnetic poles.

Claim 13

Trans-synchronous motor apparatus as claimed in claim 8 and in which the control of said switches is effected at the zero-axis crossings of said half cycles.

Claim 14

Trans-synchronous motor apparatus as claimed in claim 11 and in which means is provided to effect turn on and switch off of said motor at said zero-axis crossings.

Claim 15

Trans-synchronous motor apparatus as claimed in claim 8 and in which means is provided for interchanging the connections applying the selected half cycles of two of the windings to reverse the direction of motor operation.

Claim 16

Trans-synchronous motor apparatus as claimed in claim 8 and provided with means for deenergizing the motor apparatus when the same is running in the correct direction at its full fractional speed and at a zero-axis crossing of said half cycles, and for switching the power to a high speed winding to effect high speed motor operation.