DC-side leakage current reduction for single phase full-bridge power converter/inverter
First Claim
1. A full-bridge single phase bidirectional AC/DC power converter having two phase legs on an AC side thereof and a capacitor connected between said two phase legs, said converter includinga plurality of switches connected in a full bridge configuration,a choke comprising magnetically coupled windings connected in series in respective ones of said two phase legs,a split capacitor connected between said two phase legs and in parallel with said capacitor connected between said two phase legs, anda connection between a mid-point of said split capacitor and a mid-point of a split capacitor connected between DC voltage rails on a DC side of said power converter,wherein said switches in said full bridge configuration are driven by a pulse width modulated signal that is modified from sinusoidal modulation to provide active filtering of common mode voltage variation on said two phase legs by said full bridge configuration.
2 Assignments
0 Petitions
Accused Products
Abstract
Leakage current through stray or parasitic capacitance (which is particularly large in devices such as photovoltaic cell arrays and which are damaged by such leakage currents) due to common mode switching noise in a full bridge single phase power converter is reduced at high frequencies by magnetically coupling the two phase legs on the AC side of the power converter and connecting mid points of the AC and DC sides of the power converter and is reduced at low frequencies by use of a feedback arrangement that modifies sinusoidal modulation of the switches of the full bridge converter to function as an active filter. The magnetic coupling for the two phase legs is designed in a simple manner to avoid saturation based on volt-second considerations.
-
Citations
17 Claims
-
1. A full-bridge single phase bidirectional AC/DC power converter having two phase legs on an AC side thereof and a capacitor connected between said two phase legs, said converter including
a plurality of switches connected in a full bridge configuration, a choke comprising magnetically coupled windings connected in series in respective ones of said two phase legs, a split capacitor connected between said two phase legs and in parallel with said capacitor connected between said two phase legs, and a connection between a mid-point of said split capacitor and a mid-point of a split capacitor connected between DC voltage rails on a DC side of said power converter, wherein said switches in said full bridge configuration are driven by a pulse width modulated signal that is modified from sinusoidal modulation to provide active filtering of common mode voltage variation on said two phase legs by said full bridge configuration.
-
14. A method of reducing common mode noise and leakage current through parasitic capacitance in a single phase, full bridge power converter having unipolar modulation of switches and having two phase legs on an AC side of said power converter and a capacitor connected between said two phase legs, said method comprising steps of
magnetically coupling said two phase legs opposingly, connecting a split capacitor across said two phase legs in parallel with said capacitor connected between said two phase legs to form a mid-point on said AC side of said converter, connecting a split capacitor across a DC side of said power converter to form a mid-point on said DC side of said power converter, and connecting said mid-point of said split capacitor on said AC side of said power converter to said mid-point of said split capacitor on said DC side of said power converter wherein said switches in said full bridge configuration are driven by a pulse width modulated signal that is modified from sinusoidal modulation to provide active filtering of common mode voltage variation on said two phase legs by said full bridge configuration.
Specification