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Publication Date: 2017-Jul-06
Document File: 5 page(s) / 180K

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The Prior Art Database

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Kittilä Jukka-Pekka: AUTHOR [+5]


The disclosure relates to the control of control of power semiconductors. A solution for controlling a gate of the semiconductor component is disclosed. Generally, the idea is to use a PWM signal to control the power semiconductor. An instantaneous time average of the PWM signal may be adjusted to a desired value.

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Page 1 of 5  FI-1713701

© Copyright [2017] ABB. All rights reserved.


The disclosure relates to intelligent control of power semiconductors, such as IGBTs

(Insulated Gate Bipolar transistor). A gate of the semiconductor component is controlled

in a cost-effective and versatile yet simple manner in which the behavior of the on-state

and switching state of the component can be modified in a desired way.

A switching speed of a power semiconductor can be limited by altering a value of a series

resistance connected to the gate. It is also possible to add capacitance between the gate

and emitter to slow down the charging of the gate. A possible drawback related to this

kind of solution is that component values selected may affect the operation of the device,

which may increase power losses of the device and thus require a higher power feeding

capability from the gate control circuit, for example.

In order to enable the change of the behavior of the gate control according to the operating

point, it is possible to use several resistors and switch them into the circuit according to

the situation by using analogue switches, for example. This kind of solution is complex

and the components used may need to be dimensioned for instantaneous current of

several amperes. Alternatively, it is possible to use a PWM controlled power supply that

modulates the necessary voltage to the gate with a desired speed. A possible drawback

of this kind of solution is the high instantaneous current stress of the components used

and that high-frequency voltage pulses, e.g. +/- 15 V, are provided to the gate via various

conductors, which may cause a corresponding high-frequency gate current, which in turn

may cause severe EMC problems.

In another solution by the authors, the above-described problems were solved or

alleviated by using a modification of the control signal of the output stage of the gate

driver by using a resistor matrix. This solution is illustrated in the example of Figure 1 and

it enables certain switching combinations the number of which depends on the size of the

matrix and component values.

Page 2 of 5  FI-1713701

© Copyright [2017] ABB. All rights reserved.

Figure 1. The use of a resistor matrix in the control of the output stage.

As an alternative solution to the above-described solution it is proposed to replace the

resistor matrix controlling an emitter follower output stage with a PWM signal an

instantaneous time average of which can be adjusted practically in an unlimited manner

within a range defined by available operating voltage levels. The solution is illustrated in

Figure 2. The desired voltage average can be formed to a gate-emitter capacitor C

connected to the output stage, which for its part slows down the dynamic of the output

transistors and filters the high-frequency signal from the output signal. The PWM signal

can be obtained direct...