Booster type converter with low power loss

Details Booster type converter with low power loss Booster type converter with low power loss

1999-08-25

2001-01-16

Wong, Peter S. (Department: 2838)

Electricity: power supply or regulation systems

In shunt with source or load

Using choke and switch across source

C363S097000, C363S131000

Reexamination Certificate

active

06175219

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a booster type converter.
2. Description of the Related Art
Heretofore, a booster type converter by which a DC output having a prescribed voltage value higher than that input from a DC power source can be supplied to a load by controlling a switching duty of a boosting switching element in the booster type converter has been widely used as a power unit for electronic and electrical equipments.
FIG. 1A
is a block diagram showing an example of a conventional booster type converter
1
. This booster type converter
1
comprises a DC power source
3
, a + output terminal
3
a
of the DC power source
3
, a − output terminal
3
b
of the DC power source
3
, a reactor coil unit
5
, a power MOSFET element
7
, a main diode element
9
, a smoothing capacitor
11
, a + output terminal
13
a
, a − output terminal
13
b
, and a control circuit
14
.
The booster type converter
1
is constituted in such that the + output terminal
3
a
of the DC power source
3
is connected to an end of the reactor coil unit
5
, a drain side of the power MOSFET element
7
is connected to the other end of the reactor coil unit
5
, a source side of the power MOSFET element
7
is connected to the − output terminal
3
b
of the DC power source
3
, a connecting midpoint between the drain side of the power − MOSFET element
7
and the other end of the reactor coil unit
5
is connected to an anode side of the main diode element
9
, a cathode side of the main diode element
9
is connected to the + output terminal
13
a
, a + pole side of the smoothing capacitor
11
and a control signal input end
14
a
of the control circuit
14
are connected to a connecting midpoint between the cathode side of the main diode element
9
and the + output terminal
13
a
, a switching signal output end
14
b
of the control circuit
14
is connected to a gate side of the power MOSFET element
7
, the source side of the power MOSFET element
7
is connected to a − pole side of the smoothing capacitor
11
, and this contact point is connected to the − output terminal
13
b
, respectively.
In the above described constitution, it is intended to arrange that a voltage produced in the reactor coil unit
5
is cumulated to a voltage value of the DC power source
3
, and the resulting voltage is accumulated in the smoothing capacitor
11
through the main diode element
9
for discharging the energy during an OFF period of a switching signal which energy is accumulated in the reactor coil unit
5
during an ON period of the switching signal supplied to the gate side of the power MOSFET element
7
by controlling respective ratios of time width in respect of the OFF period and the ON period in the switching signal supplied to the gate side of the power MOSFET element
7
in the control circuit
14
based on an output voltage value of the +output terminal
13
a
in such that an output voltage value defined between the + output terminal
13
a
and the − output terminal
13
b
is kept constant at a predetermined value, whereby a voltage having a constant voltage value which is obtained by elevating a voltage value of the DC power source
3
can be applied to a load from the +output terminal
13
a
and the − output terminal
13
b
.
It is to be noted that a period designated by “OFF” represents such a period wherein a switching signal supplied to the gate of the power MOSFET element
7
from the switching signal output end
14
b
of the control circuit
14
is in an OFF state, while a period designated by “ON” represents such a period wherein the switching signal is in an ON state, respectively, in FIG.
1
B.
In the booster type converter
1
shown in
FIG. 1A
, because of production of an overlapped area designated by VIW of a voltage VDS existing between the drain and the source of the power MOSFET element
7
and a drain current ID as shown in
FIG. 1B
at the time when the switching signal supplied from the switching signal output terminal
14
b
of the control circuit
14
to the gate of the power MOSFET element
7
is turned from an “ON” state to an “OFF” state as shown in a waveform of
FIG. 1B
, a switching loss is generated at the power MOSFET element
7
in the overlapped area VIW, and heat is generated in the element
7
due to electric power loss derived from the above described loss, thereby to decrease a DC—DC conversion efficiency of the booster type converter
1
.
Since an amount of the heat generation increases in proportional to a switching frequency value of the element
7
, there has been such a disadvantage in that an improvement in the switching frequency value is limited in view of restrictions of prevention in thermal breakdown of the power MOSFET element
7
.
SUMMARY OF THE INVENTION
In view of the above described disadvantage, it is an object of the present invention to provide a booster type converter by which it makes possible to conduct a switching operation of electric current in a state where a voltage switched by a switching element is a zero voltage or the one close thereto, and to decrease a switching loss in an electric current switching circuit constituted by a switching element such as a power MOSFET element.
According to the invention, a booster type converter, comprises:
a boosting inductor being constituted from a transformer provided with an auxiliary winding,
a capacitor being connected to the auxiliary winding, whereby the capacitor being charged by means of resonance of a leakage inductance of the transformer and the capacitor, and
at the same time, it making possible to conduct zero voltage switching of the booster type converter on the basis of the electric charge charged in the capacitor, thereby to decrease a switching loss.


REFERENCES:
patent: 5402329 (1995-03-01), Wiitenbreder, Jr.
patent: 5457379 (1995-10-01), Jacobs et al.
patent: 5477131 (1995-12-01), Gegner
patent: 5481449 (1996-01-01), Kheraluwala et al.
patent: 5748457 (1998-05-01), Poon et al.
patent: 5774346 (1998-06-01), Poon et al.
patent: 5856916 (1999-01-01), Bonnet
patent: 5880940 (1999-03-01), Poon
patent: 6018469 (2000-01-01), Poon

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