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Microcomputer Controlled Integrating Phase Detection

IP.com Disclosure Number: IPCOM000050592D
Original Publication Date: 1982-Nov-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 3 page(s) / 56K

Publishing Venue

IBM

Related People

Cavill, BR: AUTHOR [+3]

Abstract

Integrating phase detection is used in two places in a motor tester. The resonant frequency of the real motor is set and measured, and the inductance parameter is used to set the resonant frequency of the real motor. The motor tester application of integrating phase detection is seen in Fig. 1. "Exclusive OR" phase detection is performed on the input signals within the microcomputer. A number of input signal sources are possible and are selected with the multiplexer (MUX). The input signals to be tested are generated by testing for the zero-crossing point of the AC signals with external comparators, resulting in digitally readable switching signals. The system constant parameters of the simulated motor are specified by the values present in multiplying DACs (digital to analog converters).

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Microcomputer Controlled Integrating Phase Detection

Integrating phase detection is used in two places in a motor tester. The resonant frequency of the real motor is set and measured, and the inductance parameter is used to set the resonant frequency of the real motor. The motor tester application of integrating phase detection is seen in Fig. 1. "Exclusive OR" phase detection is performed on the input signals within the microcomputer. A number of input signal sources are possible and are selected with the multiplexer (MUX). The input signals to be tested are generated by testing for the zero-crossing point of the AC signals with external comparators, resulting in digitally readable switching signals. The system constant parameters of the simulated motor are specified by the values present in multiplying DACs (digital to analog converters).

The digitally readable parameters whose phase difference is to be measured are read by the microcomputer. The control program, shown in Fig. 2. determines the signal relationship between the two test signals (whether B leads A or A leads B). If both A and B are off, then "IOLD" is set to "B" indicating both phases off, and if A and B are both on, "IOLD" is set to "1" indicating both phases are on. When the phases become not the same (as "exclusive OR" function), the bit "I0LD" is tested to see if a plus or minus phase change took place. Depending on the direction of the change and the previous state of the phases, the multiplying DAC system constant parameter value is either decremented or incremented. This change in the DAC value will tend to drive the system to have a smaller phase angle difference between the two signals.

Then the program waits until the two phas...