Speed sensitive field weakening control for traction motors
First Claim
1. A control for a direct current motor including a field weakening solenoid switch including a solenoid coil, said control including electronic switching means connected in series with the coil for selectively connecting the coil to a source of direct current, speed sensor means adapted for providing an electronic digital signal having a frequency directly proportional to motor speed, and circuit means adapted for receiving said digital signal and for providing an output signal for operating said electronic switching means.
2 Assignments
0 Petitions
Accused Products
Abstract
Disclosed herein is a control for a direct current motor including a field weakening solenoid switch including a solenoid coil, which control includes an electronic switch connected in series with the coil for selectively connecting the coil to a source of direct current, and a device adapted for providing an electronic digital signal having a frequency proportional to motor speed. The control also includes a first electronic comparator adapted for receiving the digital signal and for providing an output cut-in signal for operating the electronic switch so as to connect the solenoid coil to the source of direct current to effect field weakening when the motor speed increases to a predetermined field weakening cut-in speed, and a second electronic comparator adapted for receiving the digital signal and for providing an output cut-out signal for operating the electronic switch to disconnect the coil from the source of direct current so as to prevent field weakening when the motor speed increases to a predetermined field weakening cut-out speed greater than the predetermined field weakening cut-in speed.
19 Citations
14 Claims
- 1. A control for a direct current motor including a field weakening solenoid switch including a solenoid coil, said control including electronic switching means connected in series with the coil for selectively connecting the coil to a source of direct current, speed sensor means adapted for providing an electronic digital signal having a frequency directly proportional to motor speed, and circuit means adapted for receiving said digital signal and for providing an output signal for operating said electronic switching means.
- 2. A control for a direct current motor including a field weakening solenoid switch including a solenoid coil, said control including electronic switching means connected in series with the coil for selectively connecting the coil to a source of direct current, speed sensor means adapted for providing an electronic digital signal having a frequency proportional to motor speed, digital to analog conversion means coupled to said speed sensor means for receiving said digital signal and for generating a DC signal having a voltage magnitude proportional to the frequency of said digital signal and to motor speed, first comparator means for receiving said DC signal and for generating an output cut-in signal coupled to said electronic switching means for operating said electronic switching means to connect the solenoid coil to the source of direct current to effect field weakening when the speed of the motor increases to a predetermined field weakening cut-in speed, and second comparator means adapted for receiving said DC signal and for generating an output cut-out signal coupled to said electronic switching means for operating said electronic switching means to disconnect the solenoid coil from the source of direct current to prevent field weakening when the speed of the motor increases to a predetermined field weakening cut-out speed greater than said predetermined field weakening cut-in speed.
- 11. A control for a direct current motor including a field weakening solenoid switch including a solenoid coil, said control including electronic switching means connected in series with the solenoid coil for selectively connecting the coil to a source of direct current, speed sensor means including a Hall-effect switch adapted for generating an electronic digital signal having a frequency proportional to motor speed in response to a magnet passing adjacent said Hall-effect switch, the magnet being secured to a rotating member having a speed of rotation proportional to motor speed, a phase-locked-loop having an input coupled to said Hall-effect switch for receiving said digital signal, and being adapted for generating a DC signal having a magnitude proportional to the frequency of said digital signal and the motor speed, first comparator means adapted for receiving said DC signal and for generating an output cut-in signal coupled to said electronic switching means for operating said electronic switching means to connect the solenoid coil to the source of direct current to effect field weakening when the speed of the motor increases to a predetermined field weakening cut-in speed and second comparator means adapted for receiving said DC signal and for generating an output cut-out signal coupled to said electronic switching means for operating said electronic switching means to disconnect the solenoid coil from the source of direct current to prevent field weakening when the speed of the motor increases to a predetermined field weakening cut-out speed greater than said predetermined field weakening cut-in speed.
Specification