Method for controlling trip event of inverter

Patent metadata

Field	Value
Publication number	US-2016248245-A1
Application number	US-201615016185-A
Country	US
Kind code	A1
Filing date	Feb 4, 2016
Priority date	Feb 25, 2015
Publication date	Aug 25, 2016
Grant date	—

Abstract

Disclosed herein is a method for controlling a trip event of an inverter by taking into account the temperature of the inverter. The method includes: sensing a change in temperature of the inverter for an overload current measurement time using the temperature sensing circuit; determining an amount of heat emitted from the inverter based on the change in temperature; determining an electrical energy of the inverter consumed for the overload current measurement time; determining a compensation reference time based on the amount of heat and the electrical energy; and comparing the compensation reference time with the overload current measurement time to trip the inverter. As a result, the actual temperature of the inverter measured when the inverter is in operation is reflected, so that the trip event of the inverter can be controlled more accurately.

First claim

What is claimed is:

1 . A method for controlling a trip event of an inverter, the inverter comprising a switching element and a temperature sensing circuit, wherein the method comprises:
sensing a change in temperature of the inverter for an overload current measurement time using the temperature sensing circuit; determining an amount of heat emitted from the inverter based on the change in temperature; determining an electrical energy of the inverter consumed for the overload current measurement time; determining a compensation reference time based on the amount of heat and the electrical energy; and comparing the compensation reference time with the overload current measurement time to trip the inverter.

2 . The method of claim 1 , wherein the compensation reference time is determined by adding a compensation time to a trip point reference time.

3 . The method of claim 2 , wherein the compensation reference time is determined by:
t c =( Q−E )/( C×I o 2 )
wherein t c denotes the compensation reference time, Q denotes the amount of heat, E denotes the electrical energy, C denotes a proportional constant, and I o denotes an output current flowing in the switching element.

4 . The method of claim 2 , wherein the trip point reference time is determined by:
t ref =E ref /( C×I o 2 )
wherein t ref denotes the trip point reference time, E ref denotes a reference energy for determining whether to trip the inverter, C denotes a proportional constant, and I o denotes an output current flowing in the switching element.

5 . The method of claim 1 , wherein the temperature sensing circuit comprises:
a first resistor and a second resistor connected in series; and a third resistor connected to the second resistor in parallel.

6 . The method of claim 5 , wherein the third resistor is a variable resistor having a resistance inversely proportional to the temperature of the inverter.

7 . The method of claim 1 , further comprising:
calculating an actual load factor based on a ratio of an output current flowing in the switching element to a rated current of the inverter; comparing the actual load factor with a reference load factor; and determining whether to trip the inverter based on a result of the comparing.

8 . The method of claim 7 , further comprising:
comparing a switching frequency of the switching element with a reference frequency; and determining whether to interpolate the reference load factor based on a result of the comparing.

Assignees

• Lsis Co Ltd

Inventors

• Kim Hong-Seok
• Yang Chun-Suk

Classifications

• H02H3/093

  with timing means {(in general H02H3/027; thermal delay H02H3/085; timing means for undervoltage protection H02H3/247)} · CPC title

• H02H3/085

  making use of a thermal sensor, e.g. thermistor, heated by the excess current (also responsive to the temperature of the protected device H02H5/041, thermal images H02H6/00) · CPC title

• H02H7/122 Primary

  for inverters, i.e. DC/AC converters · CPC title

• H02M1/32

  Means for protecting converters other than automatic disconnection · CPC title

• H02H3/08

  responsive to excess current (responsive to abnormal temperature caused by excess current H02H5/04) · CPC title