Claims
- 1. A motor speed control system comprising:
a permanent magnet direct current electric motor, a first switch in series with the motor; a circuit in series with the first switch, the circuit at least including a resistor and a second, pulse width modulated controlled, switch in parallel with the resistor, and an electronic controller operatively associated with the first and second switches for electronically controlling the first and second switches independently and in combination to control current to the motor to operate the motor at various speeds.
- 2. The motor speed control system of claim 1, wherein the first and second switches and the controller are constructed and arranged to provide 1) a start-up mode of operation wherein current to the motor is supplied solely by the first switch, 2) an intermediate speed mode of operation wherein current to the motor is supplied partly by the first switch and partly by the second switch operating at less than a fully on condition, and 3) a full speed mode of operation wherein current to the motor is supplied by the first switch and by the second switch operating at fully on condition.
Parent Case Info
[0001] This application is a continuation-in-part of U.S. Provisional Application No. 60/324,508 filed on Sep. 24, 2001 and U.S. application Ser. No. 10/002,860, filed on Nov. 15, 2001.
Provisional Applications (1)
|
Number |
Date |
Country |
|
60324508 |
Sep 2001 |
US |
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
10002860 |
Nov 2001 |
US |
Child |
10092835 |
Mar 2002 |
US |