486 results about "Multilevel inverter" patented technology

The invention discloses an energy-saving type cascade multilevel photovoltaic grid-connected generating control system comprising an energy-saving cascade multilevel photovoltaic generating inverter, a controller and a power grid, wherein the multilevel inverter consists of 3n energy-saving type photovoltaic generating modules, wherein n modules are connected in series into one phase of a three-phase inverter; and the single-stage power of each module is converted to realize the buck-boost, the inverting and energy saving and adapt to the wide-range change of the battery voltage with high reliability. 3n photovoltaic cells and energy-saving cells are distributed on 3n modules; the generation of each module is independently controlled, thereby realizing the distributed maximum power track, collecting solar energy to the maximum extent, realizing high efficiency and avoiding the problems of power loss and hot spot caused by the local shade generated when the photovoltaic cells are connected in series; and the invention can flexibly control the stable power of a feeder grid of the multilevel inverter and achieve the functions of reactive power consumption, the power pitch peak control and the like, has the advantage of multilevel inversion and low output harmonic voltage and is suitable for high-voltage, high-power and transformer-free grid connection.

The invention discloses a method for controlling the power balance of the DC side of a cascaded multilevel inverter. The power control of the cascaded multilevel inverter is divided into two layers, an upper layer control and a lower layer control,wherein, the upper layer control realizes the total power control, and the lower layer control carries out the operation of active power redistribution on each full-bridge conversion unit by overlapping a pure active power vector which is parallel to the current direction on the basis of the upper layer control, thereby enabling the input power on the DC side of each full-bridge conversion unit of the cascaded multilevel inverter to tend to be balanced. The invention does not need to be provided with an extra power circuit, and can effectively realize the power balance of the DC side of the inverter, thereby reducing the cost fo the system and improving the reliability of the system.

A multilevel inverter using a cascade configuration with a device for equally controlling a power factor for each unit cell includes: a master controller, a plurality of power cells connected in series for each of three AC (Alternating Current) phases, a phase shift transformer for supplying a power cell input voltage, a CAN (Controller Area Network) communication network to provide a communication path between the master controller and each power cell, and cell controllers to control output voltages and output frequencies of the respective power cells according to a voltage command and a frequency command from the master controller, each cell controller having a pulse width modulator to generate a pulse width modulation control signal of a variable voltage and a variable frequency to the connected corresponding power cell, wherein each cell controller is configured to calculate a phase difference value of the corresponding power cell according to a preset total number of connected power cells and the floor number (i.e., the serial connection sequence) of the corresponding power cell to thereafter phase-shift a chopping wave by the calculated phase difference value, thereby compensating for the phase differences between each power cell.