Electricity: power supply or regulation systems – In shunt with source or load – Using choke and switch across source
Reexamination Certificate
2003-05-09
2004-09-07
Riley, Shawn (Department: 2838)
Electricity: power supply or regulation systems
In shunt with source or load
Using choke and switch across source
C323S235000, C323S225000
Reexamination Certificate
active
06788032
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a DC-to-DC converter and more particularly to a DC-to-DC converter with an active power sink circuit.
BACKGROUND OF THE INVENTION
FIG. 1
is a schematic diagram illustrating a conventional pulse width modulation (PWM) boost converter
100
. When a main switch
101
is turned on, a full bridge rectifier
102
outputs a DC power source to a main inductor
103
. Thus power is transferred from the DC power source to the main inductor
103
and stored in the main inductor
103
. Meanwhile, a main diode
104
is reverse biased. Once when a main switch
101
is turned on, power stored in main inductor
103
is transferred from the main inductor
103
to a main capacitor
105
. In theoretical, by assuming that the main capacitor
105
is large enough and the main switch
101
is turned on and off fast and periodically, electrical energy can be stored in the main inductor
103
and transferred form the main inductor
103
into the main capacitor
105
promptly. Thus the voltage across the main capacitor
105
can be maintained at a constant voltage without load variation effect.
However, during the switching operation of the main switch
101
in the boost converter, the reverse recovery current of the main diode
104
will cause the main switch
101
and the main diode
104
have a serious switching loss such that the switching frequency cannot be increased to reduce the size of the main inductor of the boost converter. Please refer to FIG.
2
.
FIG. 2
is schematic diagram illustrating another conventional pulse width modulation (PWM) boost converter
200
. The converter
200
is provided to solve the above drawback. Basically, a branch circuit which has an auxiliary inductor
206
and an auxiliary switch
207
is added into the converter
200
in order to eliminate the reverse recovery current of the main diode
204
. When the auxiliary switch
207
is turned on, the power of a main power source Vs is stored in the auxiliary inductor
206
and it causes the electrical energy of a parallel-connected capacitor
208
of the main switch
201
to be totally discharged and stored in the auxiliary inductor
206
. Thus the main switch
201
can be turned on under the zero voltage switching condition. Furthermore, when the auxiliary switch
207
is turned off, the electrical energy of the auxiliary inductor
206
is discharged form the auxiliary inductor
206
to a capacitor
205
through a diode
209
. Therefore, this technique can solve the switching loss of the main switch
101
and the main diode
104
shown in
FIG. 1
, but the switching loss of the auxiliary switch
207
is still existed (the auxiliary switch
207
is turned off), and the EMI and the RFI problem will be generated. Meanwhile, the PWM boost converter
200
further includes a full bridge rectifier
202
which is utilized to transferred an AC voltage into a DC voltage as a main power of the PWM boost converter
200
. By utilizing the conduction of the main switch
201
, the main inductor
203
can be charged by the main power.
For the above reasons, a need still exists in the art of designing and manufacturing DC/DC converter to provide an optimal configuration for low switching loss. The improved converter configuration will be described in this invention as below.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to propose a DC-to-DC converter with an active power sink circuit for eliminating switching loss of a main switch of the DC-to-DC converter by utilizing a resonant circuit to turn on the main switch under the near zero voltage switching condition and an active power sink circuit to cause a unidirectional switch to be turned off the near zero current switching condition.
It is therefore another object of the present invention to propose a clamped-mode DC-to-DC converter for generating a low voltage output and a high current output by utilizing a combined transformer-inductor device and a synchronous rectification circuit in order to minimize the primary switch loss, synchronous rectifier loss, transformer winding loss and transformer core loss.
According to an aspect of the present invention, the DC-to-DC converter includes a boost converter circuit, a resonant circuit, and an active power sink circuit. The boost converter circuit has a main switch for boosting a first DC voltage into a second DC voltage. The resonant circuit includes a unidirectional switch, a resonant capacitor, and a first winding of a transformer for causing the main switch to be controlled to exhibit near zero voltage switching. And, the active power sink circuit is magnetically coupled to the first winding of the transformer for draining energy in an inductance of the transformer off via magnetic induction between the active power sink circuit and the transformer, and causing the unidirectional switch to be controlled to exhibit near zero current switching.
Preferably, the boost converter circuit further includes a main inductor, a main diode, and a main capacitor in which when the main switch is turned on, the first DC voltage charges the main inductor and the main diode is turned off, and when the main switch is turned off, the main diode is turned on and the first DC voltage and a voltage across the main inductor charges the main capacitor to produce the second DC voltage.
Preferably, the main inductor, a first terminal of the main switch, and an anode end of the main diode are connected to a first node, and the other terminal of the main inductor is electrically connected to the first DC voltage.
Preferably, a cathode end of the main diode and a positive terminal of the main capacitor are electrically connected to a second node, and the second node is an output terminal of the second DC voltage.
Preferably, a second terminal of the main switch and a negative terminal of the main capacitor are electrically connected to a third node.
Preferably, the active power sink circuit is a push-pull DC-to-DC converter including a fist switch, a second switch, and a rectified circuit. The fist switch is electrically connected to a second winding of the transformer in series, and a series circuit of the fist switch and the second winding of the transformer electrically connected between the third node and the second node. The second switch is electrically connected to a third winding of the transformer in series, and a series circuit of the second switch and the third winding of the transformer electrically connected between the third node and the second node. And, the rectified circuit includes a secondary winding of the transformer having a first terminal, a second terminal, and a central terminal, a first diode having an anode end electrically connected to the first terminal of the secondary winding, a second diode having an anode end electrically connected to the second terminal of the secondary winding, and a cathode end electrically connected to cathode end of the first diode, and a first capacitor having a positive terminal electrically connected to a common cathode end of the first diode and the second diode, and a negative terminal electrically connected to the central terminal.
Preferably, the resonant circuit includes a third diode.
Preferably, the third diode having a cathode end is electrically connected to the first winding, and the unidirectional switch in series, and a series circuit of the third diode, the first winding, and the unidirectional switch is in parallel with the main switch and the resonant capacitor.
Preferably, the resonant circuit further includes a resonant inductor electrically connected to the first winding and the third diode in series.
Preferably, the transformer has a leakage inductance.
Preferably, the active power sink circuit is a full bridge DC-to-DC converter.
It is therefore another aspect of the present invention to propose a DC-to-DC converter including a boost converter circuit, a resonant circuit, and an active power sink circuit. The boost converter circuit has a main switch for boosting a first DC voltage into a second
Chan Chih-Chiang
Chang Yu-Ming
Delta Electronics , Inc.
Riley Shawn
LandOfFree
Softing switching DC-to-DC converter with an active power... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Softing switching DC-to-DC converter with an active power..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Softing switching DC-to-DC converter with an active power... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3252141