US 2011/0298470 A1 · DETECTION OF WELDED SWITCH CONTACTS IN A LINE CONVERTER SYSTEM

Abstract

A system for the detection of welded contacts in a circuit of a line converter system has a plurality of inverter switches, a plurality of utility switches in which a pair of utility switches is connected in series through a line to a utility, a voltage detector, an electronic controller, and a DC input source. The line converter system converts incoming DC power into AC output power that is delivered to the utility grid. The voltage detector measures the voltage across a first node and a second node of the circuit and provides an output that is interpreted by an electronic controller for each step performed during a method of detection of welded contacts. The detection method has a sequence of test steps in which at least one switch is opened and/or closed, a DC bus of the inverter or the utility grid is used as a stimulus voltage, and the voltage is measured. If a voltage is not detected across the first and second nodes, the test sequence is continued until a welded contact is detected or the electronic controller determines that none of the contacts are welded. If the controller determines that none of the contacts are welded, the line converter system is permitted to connect and supply AC power to the utility.

Claims21

Dependent claims

A line converter system for connecting a power source to a utility grid, comprising:

an inverter having a DC bus and a plurality of inverter switches;
a plurality of lines for connecting the inverter to the utility grid, each line having a first end connected to the inverter and a second end for connection to the utility grid;
a plurality of line switches, a pair of the line switches being connected in series into each of the lines;
a voltage detector connected to the lines, respectively, the voltage detector being connected to each of the lines at a point between the line switches;
and
a controller connected to the inverter switches and the line switches, the controller comprising a processor and computer readable medium having program instructions stored thereon, which when executed by the processor are operable to perform a method of detecting stuck contacts in the line switches when the line converter system is connected to the utility grid, the method comprising:
(a.) opening the inverter switches so that no voltage from the DC bus is applied to the line switches located toward the first ends of the lines;
(b.) transmitting open commands to the line switches;
(c.) after transmitting the open commands, determining whether the voltage detector has detected a voltage;
and
(d.) if the voltage detector is determined to have detected a voltage in step (c.), determining that the line switches located toward the second ends of the lines have contacts that are stuck together.

8 more elements

A method of detecting stuck contacts in a line converter system connected to a utility grid, wherein the inverter system comprises an inverter having a DC bus and a plurality of inverter switches, wherein a plurality of lines connect the inverter to the utility grid, each line having a first end connected to the inverter and a second end connected to the utility grid, and wherein a pair of line switches are connected in series into each of the lines, the method comprising:

(a.) opening the inverter switches so that no voltage from the DC bus is applied to the line switches located toward the first ends of the lines;
(b.) transmitting open commands to the line switches;
(c.) after transmitting the open commands, determining whether there is a voltage between a first point located between the line switches in a first one of the lines and a second point located between the line switches in a second one of the lines;
and
(d.) if a voltage is detected in step (c.), determining that the line switches located toward the second ends of the lines have contacts that are stuck together.

2 more elements

Dependencies are inferred from the claim text.

Detection of welded switch contacts in a line converter system

Life of this patent

Detection of welded switch contacts in a line converter system

Life of this patent

Abstract

Claims21