Resources Contact Us Home
Browse by: INVENTOR PATENT HOLDER PATENT NUMBER DATE
 
 
Apparatus and method for measuring power factor and torque on the output of variable frequency drives










Image Number 3 for United States Patent #5003252.

An apparatus and method for sensing power factor and torque on the output of a variable frequency machine is disclosed. Initially, power is sensed in each phase of the three-phase machine by utilizing Hall generators for multiplying the phase current flowing through each phase by a current proportional to a phase voltage for each phase. The products are then summed to obtain a reading of the instantaneous power drawn by the three phase machine. The AC component is filtered out of the summed signal using a multistage filter which allows for maintaining a fast response time with low ripple. This output is divided by the speed of the machine and multiplied by a constant to result in a signal representing torque. For measuring power factor, power signal sensed in each phase is applied to a DC blocking capacitor, effectively separating the AC envelope proportional to voltage times current. The three signals are applied to absolute value amplifiers and summed to provide a signal yielding total power. The instantaneous power is then divided by this signal to provide power factor.








 
 
  Recently Added Patents
Liquid crystal display device
SMS transport resource control
Submersible remote smoke sensor
Three-dimensional filter
Printing device, printing system, program, and printing method for printing based on print data from a user authorized to issue a print instruction for the print data
Image forming apparatus
Method and system for utilizing Perovskite material for charge storage and as a dielectric
  Randomly Featured Patents
Method of controlling intake air quantity for internal combustion engines
Field effect transistor with nitride compound
Semi automatic parts cleaning machine
Radiation-hardened transistor amplifiers
Single-chain polypeptides comprising troponin I N-terminal fragments and troponin C
Coexistence of wireless personal area network and wireless local area network
Circuit configuration for detecting the steering lock angle of the rear wheels of a motor vehicle
Natural flavored vegetable oil
Aluminum surface treatment to enhance adhesion in a given direction
Erasable inks containing thermoplastic block copolymers