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COMPENSATION OF THERMAL CYCLICAL CHANGES BY ALTERNATING THE GATE VOLTAGE AND THE SWITCHING SPEED

IP.com Disclosure Number: IPCOM000249829D
Publication Date: 2017-Apr-12
Document File: 5 page(s) / 138K

Publishing Venue

The IP.com Prior Art Database

Related People

Salmia Teemu: AUTHOR [+3]

Abstract

The novel method according to the invention makes it possible to reduce the cyclic changes of the temperature in the connection interface of the power semiconductor and the temperature of the bottom plate by changing the gate voltage and switching speed depending on the operation point of the apparatus. The change in the switching speed and the change in the gate voltage may depend on the temperature and/or on the collector current of the IGBT and/or on the power losses in the IGBT module. The novel method is based on the idea of alternating the fast and the slow turning-on in a suitable manner.

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Page 1 of 5  FI-1624801.1281

© Copyright [2017] ABB. All rights reserved.

COMPENSATION OF THERMAL CYCLICAL CHANGES BY ALTERNATING THE GATE

VOLTAGE AND THE SWITCHING SPEED

Abstract

The novel method according to the invention makes it possible to reduce the cyclic

changes of the temperature in the connection interface of the power semiconductor and

the temperature of the bottom plate by changing the gate voltage and switching speed

depending on the operation point of the apparatus. The change in the switching speed

and the change in the gate voltage may depend on the temperature and/or on the

collector current of the IGBT and/or on the power losses in the IGBT module. The novel

method is based on the idea of alternating the fast and the slow turning-on in a suitable

manner.

Two different novel methods for compensating thermal cyclical changes by alternating

the gate voltage and the switching speed are disclosed.

The first novel method is based on the use of a prior art gate controller. Only three

voltages can be connected to the gate, turning-on, turning-off, and soft turning-off, which

means slow turning-on. Soft turning-off is only used in short connection situations in prior

art solutions. The first novel method uses in addition to fast turning-on also slow turning-

on in turning-on.

The second novel method is based on adding a couple of components into a prior art gate

controller. The new components makes it possible to add a slow turning-on without the

need to increase the gate voltage intended for soft turning-off.

A prior art solution

In a prior art control of the gate voltage it is possible to connect only three different

voltages to the gate of the semiconductor. A first of these corresponds to a turning-on

(both upper switches are closed), a second of these corresponds to a turning-off (both

lower switches are closed), and a third of these corresponds to a soft turning-off, which

means a slow turning-on (the upper right hand switch and the lower left hand switch are

Page 2 of 5  FI-1624801.1281

© Copyright [2017] ABB. All rights reserved.

closed). A soft turning-off i.e. a slow turning-on is in prior art solutions only used during

short circuit situations. A connection arrangement according to prior art is shown in figure

1.

Kuva 1. A prior art gate control connection arrangement.

The magnitude of the gate voltage and of the resistor determine the actual magnitude of

the gate current. The turning-on of the IGBT-module may be influenced by these. The

greater the gate current is during turning-on, the faster the switching event is and the

smaller is the dissipation power caused by this switching.

Problems in the prior art solution

By changing the switching speed of the semiconductor, one can influence the switching

losses formed in the semiconductor. The greater the switching speed is, the smaller are

the turning-on losses in the IGBT. The losses in the diode will on the other hand increase

when the switching speed increases.

Only...