Cold start system for motors
AssigneeThe Singer Company
InventorGeorge Francis Schroeder
Life of this patent
Estimating the term…
Abstract
Motors, particularly gyro motors, are started by initially operating the motors at a frequency lower than their normal operating frequency so as to draw a larger current and develop greater starting torque with the maximum current and torque limited by a current limiting DC power supply. Where at least two motors are provided sequencing of the two motors is accomplished thereby permitting use of essentially the same power supply which is required for normal operation.
Claims7
A method for rapidly cold starting gyro motors in a gyro platform having at least a vertical gyro motor and an azimuth gyro motor both of which are multiphase motors normally operating at a first frequency said motors being supplied from a supply module comprising a plurality of switches for converting a DC voltage into a square wave AC voltage, said switches being supplied with appropriate switching waveforms at the normal operating frequency of the motors, comprising:
- (a) dividing the normal frequency waveforms used to control the switching means to a lower frequency;
- (b) energizing a first phase winding of both of said motors with said lower frequency;
- (c) energizing the other phase windings of one of said motors with said lower frequency for a first predetermined amount of time;
- (d) de-energizing said other windings of said first motor and energizing the other winding of said second motor, at said lower frequency;
- (e) after a second predetermined period of time, energizing all windings of both motors with normal frequency.
In a gyro motor drive system which comprises:
- (a) a crystal controlled clock;
- (b) means for dividing the clock frequency into four first signals each at a first, normal frequency, each signal having a period equal to half the total period at said frequency and the first signals being respectively displaced 90.degree. with respect to each other;
- (c) a DC power supply;
- and
- (d) a gyro wheel supply module obtaining positive and negative voltage inputs from the DC power supply and converting said DC voltage inputs into a square wave AC output utilizing said first signals,
- the improvement comprising:
- (e) means for obtaining from said first signals at said first frequency four second signals bearing the same phase relationship at a second, lower frequency;
- (f) logic means having as inputs said first and second signals adapted to respond to a control input to selectively provide one of said sets of four signals at its output, said output being coupled to said gyro wheels supply module;
- and
- (g) sequencing means to provide said control input to cause said logic means to first output said signals at said second frequency for predetermined period of time and to then output said waveforms at said first frequency.
Dependencies are inferred from the claim text.