High-precision current detection circuit based on CPU (Central Processing Unit)

Abstract

The invention relates to a high-precision current detection circuit based on a CPU (Central Processing Unit). The detection current is mainly composed of a plurality of filter capacitors, a bypass capacitor, a following resistor, an input resistor, a feedback resistor, an absolute value diode, a protected diode and an operational amplifier, wherein when the circuit works, detected current IUin passes through a current Hall sensor T1 to be converted into weak current IS; a voltage value, which corresponds to the IS, is obtained through a sampling resistor R1 and then the voltage value is carried out by operational amplification and following to obtain a voltage value IU corresponding to a circuit to be detected; the current IU, which passes through a current sensor, passes through a filtering circuit formed by a resistor R4 and the filter capacitor C2, and then is divided into two paths after the following of operational amplification U2; one path of the current passes through an absolute value circuit and a reverse uplifting circuit to obtain a positive half-wave of the current; and the other path of the current is reversed and passes through the absolute value circuit and the reverse uplifting circuit to obtain a negative half-wave of the current. The high-precision current detection circuit based on the CPU has the advantages that: a detected signal is amplified under the condition that an AD (Analog to Digital) linear zone is not changed, so that the precision can be greatly improved.

Description

technical field [0001] The invention relates to the technical field of power supplies, in particular to an output three-phase current detection circuit of a frequency converter power unit. Background technique [0002] In modern industrial applications, with the continuous development of power electronics technology, microelectronics technology and modern control theory, inverters, UPS, power supplies and other products will be used in many industrial and civil occasions. A good product needs three-phase AC The output or input current is detected in real time to meet the needs of monitoring and control. [0003] The existing methods generally use the AC signal collected by the Hall to directly raise a certain amplitude VREF through the whole to make the entire AC signal a positive value so that the AD port of the CPU is in the linear area, such as figure 1 shown. The circuit realizes three-phase output current detection, among which IUin is one phase of the three-phase out...

AI Technical Summary

Problems solved by technology

[0005] The technical problem to be solved by the present invention is to provide a high-precision circuit detection circuit in order to solve the defect of low signal sampling precision in the existing circuit

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