The document proposes a power decoupling method using a novel four-switch single-phase inverter instead of a traditional H-bridge inverter. The four-switch converter is a three-port converter that can operate independently like a conventional inverter or rectifier, unlike two-stage systems. Compared to the H-bridge inverter, the proposed topology does not require additional switches. The power of the DC and AC ports can be controlled independently by choosing control variables, with a control strategy illustrated using two inductors' current. The control parameters are similar to those of an H-bridge inverter and half-bridge DC/DC converter.

1. Softroniics
Softroniics www.softroniics.in
Calicut||Coimbatore||Palakkad 9037291113, 9037061113
A Power Decoupling Method Based on
Four Switch Three-Port DC/DC/AC
Converter in DC Microgrid
Abstract
The passive compensation approaches or the active ones to cancel the
undesirable power ripple instead of electrolytic capacitors. However, the
increase in size and cost of the passive methods limits its practical
applicability. Besides that, there are several active low-frequency ripple
compensation approaches, which can be classified into two methods in
general. One is the power converter self-controlling method (SCM), and
the other is the current ripple injecting method (CRIM). On one side, the
SCM is using the dc link inside the power system to supply the pulsating
power and reduce the ripple. The current ripple generation and propagation
in fuel cell power systems and proposed a dual-loop control method to
minish the current ripple of the fuel cell. An LC branch in the middle of
the transformer and achieved ripple control with a small dc capacitor is
proposed. A power decoupling circuit is added in the dc/dc stage to
compensate the power ripple. Three different dc link configurations are
compared, and the module integrated converter with a line frequency dc–
ac converter is proved to be the best one. In these methods, no extra
devices are needful. Thus, the overall system efficiency is guaranteed, and
the cost is attractive. Nevertheless, this kind of method is limited by the
system framework and is conducted mainly in two-stage power systems,

2. Softroniics
Softroniics www.softroniics.in
Calicut||Coimbatore||Palakkad 9037291113, 9037061113
which makes it out of common use. In addition, when applied to a power
system with a different topology, the controller needs to be redesigned. On
the other side, the CRIMs are using an additional device to afford the
alternating power so as to suppress the ripple. Even though there are
several additional devices in the CRIMs which increase cost, the CRIMs
are still praised for their mobility and reliability in various applications
since the ripple reduction is executed by the auxiliary equipment.
Existing system
H-bridge that enables a voltage to be applied across a load in either
direction. These circuits are often used in robotics and other applications to
allow DC motors to run forwards and backwards. Most DC-to-AC
converters (power inverters), most AC/AC converters, the DC-to-DC
push–pull converter, most motor controllers, and many other kinds of
power electronics use H bridges. In particular, a bipolar stepper motor is
almost invariably driven by a motor controller containing two H-bridges.
An H bridge is built with four switches (solid-state or mechanical). When
the switches S1 and S4 (according to the first figure) are closed (and S2
and S3 are open) a positive voltage will be applied across the motor. By
opening S1 and S4 switches and closing S2 and S3 switches, this voltage is
reversed, allowing reverse operation of the motor. The switches S1 and S2
should never be closed at the same time, as this would cause a short circuit
on the input voltage source. The same applies to the switches S3 and S4.
This condition is known as shoot-through.

3. Softroniics
Softroniics www.softroniics.in
Calicut||Coimbatore||Palakkad 9037291113, 9037061113
Proposed system
The paper focuses on the inverter itself and proposes a power
decoupling method based on a novel four-switch single-phase inverter
instead of the traditional H-bridge inverter. The four-switch converter is a
three-port converter which is able to operate independently like a
conventional inverter or rectifier and is not limited by two-stage systems.
Furthermore, compared with the H-bridge inverter, no switches are added
in the presented topology. After analyzing the equivalent model of such
topology, ignoring the imperfection of the switches, the power of the dc
port and ac port can be controlled without interaction by choosing the
independent variables reasonably. The corresponding power control
strategy is illustrated with two inductors’ current as a control variable.
Then, the control parameters are designed easily, which is similar with the
control parameter design of the H-bridge inverter and half-bridge dc/dc
converter.