Passive damping technology of LCL filter grid-connected inverter

The series or parallel approach of passive resistors increases system damping to address the resonance problems inherent in LCL filters. As shown in Figure 1, the passive damping method of series resistance on the capacitor branch can attenuate the LCL resonant peak to a large extent, so that the amplitude-frequency curve is below the 0dB […]

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Resonance phenomenon of filter grid-connected inverter

The three-phase inverter can be equivalent to two single-phase inverters with a coupling relationship after coordinate transformation. The research on the resonance problem can be carried out based on the single-phase grid-connected inverter model. In order to facilitate the subsequent description, Figure 1 shows a single-phase grid-connected inverter using an LCL filter. The LCL filter […]

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Low frequency harmonic suppression of incoming current

In order to achieve lower harmonic distortion of grid-connected current, problems such as low-frequency harmonic distortion of grid-connected current must be solved. This article¬†briefly analyzes the causes of low spectrum waves and introduces several current control methods for current suppression of low spectrum waves commonly used in L-filter solar grid tie inverter. Read more: Influence […]

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Power tube switching delay and turn-on voltage drop

The previous analysis only considers the influence of the artificially added dead time on the output voltage of the bridge arm and the incoming current of the bridge arm to prevent the bridge arm from passing through. However, the turn-on and turn-off of actual power devices is not instantaneous, and there is a turn-on voltage […]

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Influence of low frequency harmonics of grid voltage and dead zone effect

1. The influence of low frequency harmonics of grid voltage The equivalent model of the grid-connected inverter is shown in Figure 1, in which the output voltage uinv of the bridge arm of the inverter is equivalent to a controlled voltage source (the specific form is related to the inverter control). Using the superposition theorem, […]

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Fundamental current tracking

In order to achieve a higher power factor, the fundamental tracking error of the incoming current must be resolved. This paper briefly introduces several fundamental current tracking control methods commonly used in L-filter grid-connected inverters 1. Proportional-integral (PI) regulator The form of the PI regulator is as follows: Among them, kp is the proportional gain, Ti is […]

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Stability of current control

Overview of current control techniques for single L filter grid-tied inverters The current control block diagram of the single-L filter grid-connected inverter is shown in Figure 1. The inverter bridge is simply equivalent to a proportional link with a gain of kPWM, and kPWM is the ratio of the DC side voltage to the amplitude […]

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