Digital control system and control method of three-phase three-level pfc circuit

Abstract

The present invention relates to the technical field of digital control of power electronic circuits, in particular to a digital control system and control method of a three-phase three-level PFC circuit. The digital control system includes an input phase current sampling module, an output voltage sampling module, and a PID regulator. Turn-on time calculator, PWM module; the turn-on time calculator calculates the input phase current ia, ib, ic and the output voltage Uo adjusted by the PID regulator to obtain the turn-on time of the switch, and limit the comparator to obtain the corresponding turn-on time change The PWM module updates the comparator value of the PWM module according to the change value of the turn-on time that limits the output of the comparator, and controls the corresponding switching tubes of each phase. The digital control system and control method only need to sample the three-phase input current and output voltage, the calculation of the control quantity is simple and time-saving, the unit power factor of the circuit is realized, and the harmonic pollution is small.

Description

technical field [0001] The invention relates to the technical field of digital control of power electronic circuits, in particular to a digital control system and a control method of a three-phase three-level PFC circuit. Background technique [0002] Three-phase three-level power factor correction (PFC) circuit topology such as figure 1 As shown in the upper part, where R, S, and T are three-phase AC voltage inputs, each phase input is respectively connected to inductors L1, L2, and L3, and the other ends of the inductors are respectively connected to diodes D1, D2, D3, D4, D5, and D6. The midpoints A, B, and C of the bridge circuit, and the N poles of the diodes D1, D3, and D5 are commonly connected to the output capacitor C u The positive pole is the positive pole output P of the circuit, and the P poles of diodes D2, D4, and D6 are commonly connected to the output capacitor C d The negative pole is the negative pole output N of the circuit, and S1, S2, and S3 are three...

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Problems solved by technology

[0003] At present, there are many methods for the control of three-level PFC circuits. Chinese patents 200910145279.1 and 200710080000.7 both provide a space vector control method, and 200910128568.0 provides a method for optimizing switching operations to ensure that the phase of the current is consistent with the voltage; domestic journals Some people also provide one-cycle (One-Cycle) control methods in the literature; these control methods have their own characteristics. Vector control is a control method based on digital chips, which can be flexibly applied in practice and is suitable for high-power applications. However, its algorithm is relatively complicated, and it needs to sample the input voltage, input current, output voltage and current of the three phases, which increases the complexity of the device; the method of single-cycle control is relatively simple, no need to sample the input voltage, only need to Current and output voltage are sampled, but because real-time input current is required to participate in the comparison to obtain the control amount, it is difficult to use digital chips to achieve single-cycle control

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