The invention relates to the technical field of current detection, in particular to a
current sensor of an
operational amplifier summing circuit, which comprises a frequency converter output end, a frequency converter load end, a precision
resistor, an isolation acquisition
chip, an
operational amplifier circuit, a summing circuit and a singlechip ADC (
Analog to Digital Converter) sampling port, and is characterized in that the precision
resistor is connected with the frequency converter output end and the frequency converter load end through a
welding copper bar; the isolation acquisition
chip is connected with the precision
resistor in a
welding mode, the precision resistor outputs analog signals through
voltage of the
operational amplifier circuit and the summing circuit, the analog signals are acquired to an ADC sampling port of the single-
chip microcomputer through the isolation acquisition chip, and the single-chip
microcomputer calculates an actual current value. The detection precision is higher, the
Ohm law and precise resistance sampling are adopted, analog signals are output to a sampling port of the
single chip microcomputer ADC to calculate the actual current value, the current detection precision can be within + / -0.5% and is far higher than the 3% deviation of a traditional Hall sensor, the precise requirement of a
control system is met, and the phenomenon of fault
false alarm is reduced.