All-digital fluxgate type closed-loop current sensor and current signal acquisition method thereof
A current sensor and current signal technology, applied in the direction of measuring current/voltage, voltage/current isolation, and using digital measurement technology for measurement, etc., can solve the problems of reduced measurement accuracy, achieve high precision, increase output current, and improve accuracy Effect
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specific Embodiment approach 1
[0041] Specific embodiment one: the following combination figure 1 and figure 2 Illustrating this embodiment, the all-digital fluxgate type closed-loop current sensor in this embodiment includes a winding structure and a processing circuit; the winding structure includes a primary winding 14 located on the primary side of the magnetic core and a detection winding located on the secondary side of the magnetic core;
[0042] The detection winding includes two excitation windings 3, a feedback compensation winding 6 and an AC winding 13;
[0043] The processing circuit includes an excitation unit, a phase-sensitive demodulation unit and a current compensation unit;
[0044] The excitation unit is used to generate a high-frequency square wave signal, and drives the two excitation windings 3 to generate an excitation magnetic field; the phase-sensitive demodulation unit is used to extract the current of the AC winding 13 and the excitation winding 3;
[0045] The current compens...
specific Embodiment approach 2
[0066] Specific embodiment 2, the current signal acquisition method of a full-digital fluxgate type current sensor described in this embodiment, the implementation of the full-digital fluxgate type closed-loop current sensor described in specific embodiment 1 of the method specifically includes:
[0067] Step 1. Exciting the excitation winding 3 with a high-frequency square wave signal to generate an excitation magnetic field;
[0068] Step 2. When the measured current includes a DC current, in the excitation magnetic field, the current signal of the excitation winding 3 is collected by AD sampling, and the DC current variation of the circuit under test is obtained, and the second harmonic is performed after filtering the DC current variation. wave extraction;
[0069] When the measured current includes AC current, the AC variation of the measured current is obtained directly through the AC winding;
[0070] Step 3: Summing the extracted second harmonic signal and the AC vari...
specific Embodiment
[0073] The first step: use the pwm function of the chip model TMS320F28335 to send out a 40kHz square wave signal with a duty cycle of 50%. The square wave signal amplifies the signal into a 15v power drive signal through the power tube MOSFET chip IRF640 and sends it to The excitation winding is formed to form the excitation magnetic field. Since the excitation winding uses the same magnetic core and has the same number of turns, but the winding direction is opposite, the magnetic field is zero without current change.
[0074] Step 2: When the external detected current changes, due to the influence of magnetic core saturation and rectangular hysteresis loop, the excitation magnetic field changes, and the generated current is output through the different end of the excitation winding; this current is sampled by AD. At the same time, through low-pass filtering and current second harmonic extraction, and then through the method of integration, the current value is obtained inside...
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