Inversion control method of photovoltaic grid-connected inverter
An inverter control and inverter technology, which is applied in the inverter control field of photovoltaic grid-connected inverters, can solve the problems such as the DQ control method cannot directly control the oscillating current, the system is unstable, etc., and can solve EMC and common mode current. induced oscillation, reduce noise, improve the effect of common mode voltage reduction
Active Publication Date: 2015-10-28
AISWEI NEW ENERGY TECHNOLOGY (YANGZHONG) CO LTD
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If you also use Figure 5 and Figure 6 control method, since the connection between O and M points exists, then , for the 3rd and 3rd multiple harmonic currents generated by the three phases a, b, and c, most of them will return from O to M on the AC current, so that Iz will be generated on each of the 3rd and 3rd multiple harmonics, so that The DQ control method cannot directly control the possible oscillating current
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[0033] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, so as to define the protection scope of the present invention more clearly.
[0034] The present invention adopts the attached image 3 And attached Figure 4 topological circuit. Its specific control method can be as follows Figure 6 shown.
[0035] This control is applied to the controller of the Iz current introduced by ia+ib+ic≠0. Since the generated Iz current cannot be directly controlled by the DQ axis control, a new controller must be designed for the Iz current to complete the closed-loop control purpose. Figure 7 As shown in the zero sequence controller, the output of the controller is directly superimposed on the output of the SVM, acting directly in front of the PWM generator.
[0036] Specific...
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The invention discloses an inversion control method of a photovoltaic grid-connected inverter, which comprises the steps of collecting ia, ib and ic; performing clark conversion to obtain ialpha, ibelta and iz; performing park conversion on the ialpha and the ibelta to obtain isq and isd; performing addition-subtraction and comparing between the isq and the isd as well as isqref and isdef respectively; enabling the modified and compared outcome to pass the rear voltage reference values Vsqref and Vsdref of a first PI (proportional-integral) controller, and generating Vsalpharef and Vsbeltaref through the park conversion; outputting and overlapping the Vsalpharef and Vsbeltaref passing through an SVM (space vector modulation) controller onto the input end of a PWM (pulse width modulation) controller; performing addition-subtraction and comparison on the zero sequence current iz and the zero sequence reference current izref and overlapping the outcome, obtained after addition-subtraction and comparison and passing a second PI controller, to the input end of the PWM controller, and adjusting the voltage by the PWM controller.
Description
technical field [0001] The invention relates to an inverter control method of a photovoltaic grid-connected inverter. Background technique [0002] Such as this figure 1 As shown, the traditional NPC three-level inverter bridge generally adopts the traditional space vector modulation method, which can effectively reduce the size of the output THD. But for the inverter system using three-level SVM modulation algorithm. Although it has greatly improved the output harmonics and common-mode voltage equivalent to the traditional two-level, but for photovoltaic grid-connected systems, the emission generated by its common-mode voltage is also likely to cause EMC to exceed the standard. EMI filter design is difficult and expensive. [0003] like figure 2 As shown, in the three-level space vector (SVM) control algorithm, the common mode voltage value has the following situations (assuming that when the upper transistor of each phase is turned on, the voltage is P(Vdc / 2); w...
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IPC IPC(8): H02M7/5387H02J3/38
CPCY02E10/563Y02E10/56
Inventor 吴招米
Owner AISWEI NEW ENERGY TECHNOLOGY (YANGZHONG) CO LTD