Gate driving circuit for power semiconductor switch

Details Gate driving circuit for power semiconductor switch Gate driving circuit for power semiconductor switch

2000-07-13

2001-07-31

Lam, Tuan T. (Department: 2816)

Miscellaneous active electrical nonlinear devices, circuits, and

Signal converting, shaping, or generating

Having specific delay in producing output waveform

C327S428000, C327S438000

Reexamination Certificate

active

06268754

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a gate driving circuit for a power semiconductor switch, and more particularly to a pulse driving circuit for driving abruptly or steeply a power semiconductor switch into a conductive state at a very high speed.
2. Description of the Related Art
In the power energy field, there has been developed a pulse power technique. In the pulse power technique, energy is first stored at a very slow rate, and then the stored energy is instantaneously discharged within an extremely short time period such as 100 nano-seconds to obtain extremely high power not less than 10
8
Watts. In order to discharge a large amount of energy as fast as possible, it is required to provide a high speed switching element which can operate at a high voltage. To this end, there have been proposed to utilize gap switch and thyratron. However, these switches could not be operated at a sufficiently high frequency and a life time of these switches is rather short.
Recently there have been developed various kinds of power semiconductor switching elements such as thyristor, static induction thyristor, gate turn-off thyristor (GTO) and insulated-gate bipolar transistor (IGBT), which have a high speed switching property at a rather high voltage and a relatively large current. These power semiconductor switching elements have been practically used. Particularly, a series circuit of these power semiconductor switching elements could be utilized as a high voltage power semiconductor switch for the pulse power application.
In order to drive the above mentioned power semiconductor switch in a pulse mode, the switch has to be turn-on as fast as possible. To this end, upon triggering, a large current raising very sharply must flow into a gate of the power semiconductor switch for an initial short time period of several tens nano-seconds (ns), and then an on-current of about 1 A has to be flown continuously for about 50 micro-seconds (&mgr;s). There have been proposed several gate driving circuits which can drive the power semiconductor switch in the pulse mode just explained above.
FIG. 1
is an example of known gate driving circuits for driving a power semiconductor switch in a pulse mode. A first DC voltage source
1
for turning-on a semiconductor switch and a second DC voltage source
2
for turning-off a semiconductor switch are provided. A series circuit of a resistor
3
and a capacitor
4
is connected across the turn-on DC voltage source
1
, and a junction point between the resistor
3
and the capacitor
4
is coupled with a gate G of a power semiconductor switch
6
by means of a turn-on switching element
5
. A stray inductance contained in a circuit portion from the DC voltage source to the gate G of the power semiconductor switch
6
is represented as an inductor
7
which is connected between the turn-on switching element
5
and the gate G of the power semiconductor switch
6
.
The above mentioned resistor
3
serves not only as a charging resistor for the capacitor
4
but also as a resistor for supplying a current to the gate G of the power semiconductor switch
6
for maintaining the power semiconductor switch in the conducting state. A cathode K of the power semiconductor switch
6
is connected to a negative terminal of the turn-on DC voltage source
1
, and a junction point between the turn-on switching element
5
and the inductor
7
is coupled with a negative terminal of the turn-off DC voltage source
2
by means of a turn-off switching element
8
. The turn-on and turn-off switching elements
5
and
8
are controlled by a control circuit
9
.
Now the operation of the known gate driving circuit illustrated in
FIG. 1
will be explained with reference to signal waveforms shown in FIG.
2
. When the power semiconductor switch
6
is in the non-conducting state, the turn-on switching element
5
(SW
5
) is made off and the turn-off switching element
8
(SW
8
) is made on under the control of the control circuit
9
. Therefore, the capacitor
4
is charged by the turn-on DC voltage source
1
by means of the resistor
3
to a voltage E
1
which is equal to the output voltage of the turn-on DC voltage source
1
.
At a time instant t
0
, the turn-on switching element
5
is switched from “off” to “on”, and then energy stored in the capacitor
4
flows through the turn-on switching element
5
to the gate G of the power semiconductor switch
6
, and further flows to the cathode K of the semiconductor switch. A maximum value of the current flowing from the gate G to the cathode K of the power semiconductor switch
6
is denoted as I
2
in FIG.
2
. Since the large current I
2
flows to the gate G of the power semiconductor switch
6
, this switch is turned-on and a large current flows through the anode-cathode A-K path by means of main DC voltage supply source not shown. After that, the power semiconductor switch
6
is kept conductive as long as the current flows into the gate G of the power semiconductor switch. At an instant t
1
, the turn-on switching element
5
is turned-off and the turn-off switching element
8
is turned-on by the control circuit
9
, and then the power semiconductor switch
6
is turned-off.
A raising rate (di
G
/dt) of the gate current I
G
flowing into the gate G of the power semiconductor switch
6
when the turn-on switching element
5
is made on, is determined by the voltage E
1
of the turn-on DC voltage source
1
and the stray inductance L
S
denoted by the inductor
7
in FIG.
1
. That is to say, the raising rate (di
G
/dt) can be expressed by di
G
/dt=E
1
/L
S
. Usually the stray inductance L
S
is about 100 nH and the raising rate (di
G
/dt) of the gate current is required not less than 3000 A/&mgr;s. Therefore, the voltage E
1
of the turn-on DC voltage source
1
has to be not lower than 300 V.
An amount of charge Q to be supplied to the gate G of the power semiconductor switch
6
for turning-on the power semiconductor switch at a high speed is determined by respective switches. This amount of charge Q is identical with an amount of charge stored in the capacitor
4
, and its energy is represented by ½×QE
1
. An energy loss in the resistor
3
for storing such energy is also expressed by ½×QE
1
. Therefore, the turn-on DC voltage source
1
has to supply a sum of these energy and is equal to QE
1
.
Now it is assumed that the capacitor
4
has a capacitance of 0.5 &mgr;F and a pulse repetition frequency is 2 KHz. Then the turn-on DC voltage source
1
must supply a power of 90 W. Since the turn-on DC voltage source
1
must supply the current for keeping the power semiconductor switch
6
conductive for 50 &mgr;s, and this current amounts to a power of 30 W. Therefore, the turn-on voltage source
1
must supply a sum of these powers which amounts to a very large value of 120 W.
SUMMARY OF THE INVENTION
The present invention has for its object to provide a novel and useful gate driving circuit for a power semiconductor switch, in which the above mentioned drawbacks of the known gate driving circuits and the semiconductor switch can be driven in the pulse mode by flowing abruptly a large current to a gate of the power semiconductor switch.
According to the invention, a gate driving circuit for driving a power semiconductor switch in a pulse mode comprises:
a DC voltage source having first and second output terminals, said first output terminal being connected to a main electrode of a power semiconductor switch;
a series circuit of a reactor and a first switching element, said series circuit being connected across the main electrode and a gate of the power semiconductor switch;
a second switching element connected across the gate of the power semiconductor switch and said second output terminal of the DC voltage source; and
a control circuit for controlling said first and second switching elements such that said power semiconductor switch is kept in non-conductive by making said first and second switching elements in off-state and in on-state, re

Affiliated with

Also associated with

Rating

Gate driving circuit for power semiconductor switch does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Gate driving circuit for power semiconductor switch, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gate driving circuit for power semiconductor switch will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2483445