Patents by Inventor Chee Ngai Woo

Chee Ngai Woo has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • System and method for using and controlling permanent magnet AC motor in place of triac-controlled PSC motor
    Patent number: 10263544
    Abstract: A system and method for controlling a speed of a permanent magnet AC motor (38) based on a delay angle of a triac-controlled AC voltage signal (66) from a triac (34). A simulated load (54) connected to the triac (34) enables a load current and creates the signal (66). A first detector (48) detects a zero-crossing point of the AC voltage signal, and a second detector (50) detects a subsequent turn-on instance of the triac (34). A speed command generator (52) measures an interval between the zero-crossing point and the subsequent turn-on instance, and converts the delay angle to a speed command for controlling the speed of the motor (38). The simulated load (54) may include resistors (70) having a resistance which causes the load current to be below a holding current rating of the triac (34), thereby causing the triac (34) to turn off after the interval has been measured.
    Type: Grant
    Filed: May 23, 2018
    Date of Patent: April 16, 2019
    Assignee: Nidec Motor Corporation
    Inventors: Chee Ngai Woo, Peng Fei Sun, Hui Zheng
  • SYSTEM AND METHOD FOR USING AND CONTROLLING PERMANENT MAGNET AC MOTOR IN PLACE OF TRIAC-CONTROLLED PSC MOTOR
    Publication number: 20180269812
    Abstract: A system and method for controlling a speed of a permanent magnet AC motor (38) based on a delay angle of a triac-controlled AC voltage signal (66) from a triac (34). A simulated load (54) connected to the triac (34) enables a load current and creates the signal (66). A first detector (48) detects a zero-crossing point of the AC voltage signal, and a second detector (50) detects a subsequent turn-on instance of the triac (34). A speed command generator (52) measures an interval between the zero-crossing point and the subsequent turn-on instance, and converts the delay angle to a speed command for controlling the speed of the motor (38). The simulated load (54) may include resistors (70) having a resistance which causes the load current to be below a holding current rating of the triac (34), thereby causing the triac (34) to turn off after the interval has been measured.
    Type: Application
    Filed: May 23, 2018
    Publication date: September 20, 2018
    Applicant: Nidec Motor Corporation
    Inventors: Chee Ngai Woo, Peng Fei Sun, Hui Zheng
  • System and method for using and controlling permanent magnet AC motor in place of triac-controlled PSC motor
    Patent number: 9998041
    Abstract: A system and method for controlling a speed of a permanent magnet AC motor (38) based on a delay angle of a triac-controlled AC voltage signal (66) from a triac (34). A simulated load (54) connected to the triac (34) enables a load current and creates the signal (66). A first detector (48) detects a zero-crossing point of the AC voltage signal, and a second detector (50) detects a subsequent turn-on instance of the triac (34). A speed command generator (52) measures an interval between the zero-crossing point and the subsequent turn-on instance, and converts the delay angle to a speed command for controlling the speed of the motor (38). The simulated load (54) may include resistors (70) having a resistance which causes the load current to be below a holding current rating of the triac (34), thereby causing the triac (34) to turn off after the interval has been measured.
    Type: Grant
    Filed: February 16, 2017
    Date of Patent: June 12, 2018
    Assignee: Nidec Motor Corporation
    Inventors: Chee Ngai Woo, Peng Fei Sun, Hui Zheng