System for driving a reactive load

Details System for driving a reactive load System for driving a reactive load

2000-12-18

2003-03-25

Jackson, Stephen W. (Department: 2836)

Electrical transmission or interconnection systems

Switching systems

Condition responsive

C307S043000, C307S115000, C307S125000

Reexamination Certificate

active

06538346

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a system for driving a reactive load.
BACKGROUND OF THE INVENTION
For simplicity of description, reference will be made below to applications in which the reactive load is capacitive but it is intended that the invention may, in practice, also be implemented in just the same manner in applications in which the reactive load is inductive, bearing in mind the equivalence of the voltage and current behavior of capacitances and inductances.
In order to supply energy to a load in a controlled manner, be it a capacitive, an inductive, or a resistive load, it is well known to use an amplifier supplied by a direct-current voltage supply and controlled so as to modulate the supply of a variable quantity of energy to the load in predetermined manner, that is, so as to achieve a given current or voltage waveform in the load.
An application of this type with a capacitive load is shown in
FIG. 1
of the appended drawings. An amplifier
1
has an output stage represented schematically by two controllable current sources G
1
, G
2
, connected in series between the rails of a voltage supply, indicated Vs and by the earth symbol. The output terminal of the amplifier, which is the connection node between the two current sources is connected to a capacitive load represented by a capacitor Cl. A control circuit
2
supplies control signals to the amplifier so as to modulate the supply or absorption of current by the current sources G
1
and G
2
, and hence the supply to the load Cl, in accordance with a predetermined program.
It is assumed that current is supplied to the load Cl so as to achieve therein a voltage waveform as shown in
FIG. 2
, that is, that the capacitor Cl is to be charged from 0 to a voltage V
1
, starting from a time t
0
, in a period t
0
-t
1
, the charge in the capacitor Cl is constant in a period t
1
-t
2
, and that it is to be discharged in a period t
2
-t
3
. After a delay period t
3
-t
4
, the capacitor Cl is again charged in period t
4
-t
5
. The control circuit
2
will therefore activate the current source G
1
from the time t
0
to the time t
1
with the current source G
2
deactivated, deactivate the current source G
1
in period t
1
-t
2
, activate the current source G
2
in period t
2
-t
3
with the current source G
1
deactivated, deactivate the current source G
2
in period t
3
-t
4
, and reactivate the current source G
1
in period t
4
-t
5
.
A graph of the current I in the load Cl as a function of time is shown in
FIG. 3 and a
graph of the power Pd dissipated in the current sources G
1
and G
2
as functions of time is shown in FIG.
4
. It can easily be shown that, in a practical embodiment, if Cl=2 &mgr;F, t
0
-t
1
=6 &mgr;s, t
1
-t
2
=4 &mgr;s, Vl=35V and Vs=40V, there is a constant charge current I
1
=11.6 A, a constant discharge current I
2
=17.5 A, an instantaneous maximum power P
1
=464 W dissipated in the current source G
1
, an instantaneous maximum power P
2
=612.5 W dissipated in the current source G
2
, a mean power in the period t
0
-t
1
of 156.6 W, a mean power in the period t
2
-t
3
of 122.5 W, and a total power dissipated in the period t
0
-t
3
of 272.1 W. The areas A
1
, A
2
, and A
3
represent the power dissipated by the error amplifier
1
.
SUMMARY OF THE INVENTION
In many applications, the power dissipation of the system described above is considered excessive. A need has therefore arisen for alternative systems for driving a reactive load with lower power dissipation.
According to an embodiment of the present invention a system for driving a reactive load is presented. The system includes means for controlling a load by supplying variable quantities of energies to the load in a predetermined manner as well as a reactive component coupled to the load through an electronic switch that forms a resonant circuit with the load when the switch is closed. The system also includes means for activating the switch and a control unit coupled to both the supply means and the activation means to coordinate their operation to supply energy to the load in a predetermined manner.


REFERENCES:
patent: 4691270 (1987-09-01), Pruitt
patent: 5260606 (1993-11-01), Young
patent: 5264736 (1993-11-01), Jacobson
patent: 5493183 (1996-02-01), Kimball
patent: 5541829 (1996-07-01), Maehara et al.
patent: 5559478 (1996-09-01), Athas et al.
patent: 5747947 (1998-05-01), Hak
patent: 5764496 (1998-06-01), Sato et al.
patent: 6181031 (2001-01-01), Pidutti et al.
patent: 0 667 733 (1995-08-01), None
patent: 0 730 392 (1996-09-01), None
patent: 0 809 421 (1997-11-01), None
patent: 2 196 805 (1988-05-01), None
patent: 2-67006 (1990-03-01), None
patent: 10-174436 (1998-06-01), None
patent: WO 86/05304 (1986-09-01), None

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