A current correction method suitable for wideband input pfc circuit

Abstract

The invention relates to a current correction method suitable for wide-band input PFC circuits. Step 1: Detect the input grid voltage, input grid current and input grid frequency in the circuit to obtain multiple variables of the input grid; Step 2: Select the detected multiple variables One or more of the variables, and select the compensation amount according to requirements; Step 3, using the compensation amount found from the look-up table to compensate the PFC circuit, thereby correcting the switch current distribution of the PFC circuit; Compensating the PFC circuit can generally be described as compensating for Ton at different phase angles within a sinusoidal cycle, and Ton is the turn-on time of the drive transistor in a switching cycle. Utilizing the method and system of the present application realizes that the input current can better track the input voltage and achieve better power factor under the application condition of relatively high grid frequency.

Description

technical field [0001] The invention belongs to the field of circuit parameter adjustment, and in particular relates to a current correction method suitable for wide-band input PFC circuits. Background technique [0002] Compared with the PFC circuit in CCM mode, the PFC circuit controlled by BCM mode can achieve soft turn-on of the switch tube and zero-current turn-off of the rectifier tube, so the switching performance requirements of the device are relatively low, and relatively high efficiency can be obtained. At the same time, the cost of the whole circuit can be effectively controlled, and better EMC performance can be obtained at the same time, so it has a very wide application in some ACDC power supplies with low power, but at the same power level, the PFC circuit controlled by BCM The maximum ripple of the inductor current is twice the peak value of the input current, so the ripple current is obviously larger than that of the PFC controlled by CCM, which requires a ...

AI Technical Summary

Problems solved by technology

[0002] Compared with the PFC circuit in CCM mode, the PFC circuit controlled by BCM mode can achieve soft turn-on of the switch tube and zero-current turn-off of the rectifier tube, so the switching performance requirements of the device are relatively low, and relatively high efficiency can be obtained. At the same time, the cost of the whole circuit can be effectively controlled, and better EMC performance can be obtained at the same time, so it has a very wide application in some ACDC power supplies with low power, but at the same power level, the PFC circuit controlled by BCM The maximum ripple of the inductor current is twice the peak value of the input current, so the ripple current is obviously larger than that of the PFC controlled by CCM, which requires a stronger filter circuit on the input side of the PFC, so the input EMC X capacitance is relatively large, and it will This leads to phase shift and waveform distortion of the current waveform, resulting in deterioration of PF power factor and THD total harmonic distortion. This situation is more serious when the frequency of the input power grid is relatively high (for example, the frequency of the aircraft application power grid is 360Hz to 800Hz). If the waveform is not corrected, the input current waveform and the input voltage waveform will produce obvious phase shift, and the current waveform will produce obvious distortion, so it can be compensated and corrected by digital control

[0003] Light load will lead to phase shift and waveform distortion of the current waveform, resulting in deterioration of PF power factor and THD total harmonic distortion. In the case of 360Hz-800Hz), the performance is more serious. If the waveform is not corrected, the input current waveform and the input voltage waveform will have a significant phase shift, which will increase the apparent power of the grid and increase the loss of the line.

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