Electricity: power supply or regulation systems – In shunt with source or load – Using choke and switch across source
Reexamination Certificate
2000-06-15
2003-02-25
Sterrett, Jeffrey (Department: 2838)
Electricity: power supply or regulation systems
In shunt with source or load
Using choke and switch across source
C323S225000, C323S272000
Reexamination Certificate
active
06525513
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The invention relates to a soft switching topological circuit, more particularly to a soft switching topological circuit in a boost or buck converter circuit and a bridge circuit.
BACKGROUND OF THE INVENTION
The prior art working procedures of a ZVT-BOOST circuit are shown as in
FIGS. 2A-2F
.
FIG. 2A
shows the waveform of the gate driving signal voltage V
gs2
of the auxiliary MOSFET
106
;
FIG. 2B
shows the waveform of the gate driving signal voltage V
gs1
of a main MOSFET
103
;
FIG. 2C
shows the waveform of the current I
lr
in resonant inductor
105
;
FIG. 2D
shows the waveform of current I
Dmain
of main ultrafast recovery diode
107
;
FIG. 2E
shows the waveform of the current I
Daux
of auxiliary ultrafast recovery diode
108
;
FIG. 2F
shows the waveform of the voltage V
dsmain
between the source and the drain of main MOSFET
103
. It can be seen from the above drawings:
When t=to, auxiliary MOSFET
106
is turned on, since the current flowing through an inductor, can not change abruptly, so, when auxiliary MOSFET
106
is turned on, the current in resonant inductor
105
increases gradually from an initial value, therefore the current flowing through main ultrafast recovery diode
107
decreases, and gradually to zero, thereby a soft turn-off of main ultrafast recovery diode
107
is realized by means of resonant inductor
105
;
It can be seen from
FIG. 2D
, at the moment t=t
1
, the forward current of main ultrafast recovery diode
107
reduces to zero smoothly, thereby realizing a soft turn-off of main ultrafast recovery diode
107
;
After the soft turn-off of main ultrafast recovery diode
107
, resonant inductor
105
resonates with resonant capacitor
104
, as shown in
FIG. 2F
, at the moment t=t
2
, when the voltage on resonant capacitor
104
resonates to zero, i.e., the voltage V
dmain
between the drain and source of main MOSFET
103
is also zero, the parasitic diode of main MOSFET starts turn-on and freewheel.
During the freewheeling period of the parasitic diode of main MOSFET
103
, at the moment t=t
3
, main MOSFET is turned on while auxiliary MOSFET
106
is turned off, thus, realizing a zero voltage turn on of main MOSFET
103
, at this moment, the stored energy in resonant inductor
105
is fed into output filter capacitor
109
through auxiliary ultrafast recovery diode
108
, since the voltage between the drain and source of auxiliary MOSFET
106
is limited by the voltage Vo on output filter capacitor
109
through auxiliary ultrafast recovery diode
108
, thereby also realizing a voltage clamping of auxiliary MOSFET
106
when it is turned off;
As shown in
FIG. 2E
, at the moment t=t
4
, the stored energy in resonant inductor
105
is completely released, i.e. the current flowing through auxiliary ultrafast recovery diode
108
is reduced smoothly to zero, and a soft turn-off of auxiliary ultrafast recovery diode
108
is realized,
At the moment t=t
5
, main MOSFET
103
is turned off, resonant capacitor connected in parallel to main MOSFET
103
accomplishes a zero voltage turn-off of main MOSFET
103
as shown in
FIG. 2F
; along with the rise of the voltage V
dsmain
between the drain and source of main MOSFET
103
, voltage V
dsaux
between the drain and source of auxiliary MOSFET
106
will also rise due to the resonance of resonant inductor
105
and the output parasitic capacitor of auxiliary MOSFET
106
, and the current flowing through resonant inductor
105
also rises resonantly, as shown in
FIG. 2C
;
At the moment t=t
6
, when the voltage V
dsaux
between the drain and source of auxiliary MOSFET
106
equals the voltage on output filter capacitor
109
, i.e. equals to the voltage Vo on load resistor
110
, the current in resonant inductor
105
will flow to the output filter capacitor
109
through auxiliary ultrafast recovery diode
108
, while at this moment main ultrafast recovery diode
107
is turned on, thus the voltage drop withstood on resonant inductor
105
is zero, it can be seen according to V=Lr·di/dt=0, the current flowing through resonant inductor
105
remains unchanged until auxiliary MOSFET
106
is turned on, therefore, at the moment t=t
7
, when auxiliary MOSFET
106
is turned on again periodically, it is a non-zero current turn-on.
The converter circuit has been disclosed in China Patent Application CN 95190525.2. The circuit diagrams and the working procedures are shown in
FIGS. 1 and 2
. When the circuit is at the moment t=
6
, and the voltage V
dsaux
between the drain and source terminal of an auxiliary MOSFET
106
equals the voltage on an output filter capacitor
109
, i.e. the voltage Vo on load resistor
110
, the current of resonant inductor
105
flows to output filter capacitor
109
through auxiliary ultrafast recovery diode
108
, but at this time, main ultrafast recovery diode
107
is turned on, therefore, the voltage drop of resonant inductor
105
is zero, it can be seen from V=Lr·di/dt=0 that before auxiliary MOSFET
106
is turned on, the current flowing through the resonant inductor
105
remains unchanged so, therefore at the moment t=t
7
, when auxiliary MOSFET
106
is turned on again periodically, it is a nonzero current turn-on.
Due to the above reason, the turn-on of auxiliary MOSFET
106
at the moment t=to is a non-zero current turn-on, thereby resulting in a fact that the turn-off of auxiliary ultrafast recovery diode
108
at t=to is a hard turn-off, so the turn-on loss of auxiliary MOSFET
106
and the turn-off loss of the corresponding auxiliary ultrafast recovery diode
108
are relatively large.
SUMMARY OF THE INVENTION
The invention gives out an improved ZVT power converter circuit, through which the drawbacks of the above-mentioned invention can be overcome, thus realizing a zero-current turn-on for the auxiliary MOSFET and a soft turn-off for auxiliary ultrafast recovery diode.
A basic principle on the invention is to utilize the resonance of a resonant inductor and a resonant capacitor after the auxiliary switch is turned on to realize a zero-voltage turn-on for the main switch. What is more important is that the energy feed device has no energy feed-out when the auxiliary switch is turned on, thereby achieving a zero current turn-on for the auxiliary switch, and the circuit running efficiency is raised.
The invention includes the following circuit, which comprising: a main switch, an auxiliary switch, a freewheel diode in parallel with the main switch, a resonant capacitor, a current source, a resonant inductor, a main diode, an energy-feed device and a voltage source. In which the resonant capacitor is connected to the main switch in parallel, the main and auxiliary switches are turned on and off periodically, at the same time when the auxiliary switch is turned off, the main switch is turned on simultaneously, but the auxiliary switch is not turned on until the main switch is turned off for a period of time. In the boost converter circuit, said current source and said auxiliary switch form a loop, wherein the cathode of said main diode is connected to the positive electrode of said voltage source to form a serial branch, which is connected in parallel to said main switch; in the buck converter circuit, said voltage source, main switch and main diode form a loop, wherein the negative electrode of said voltage source is connected to the anode of the main diode, the current source is connected in parallel to the serial branch formed by the main diode and said resonant inductor. In these two converters, the resonant inductor is inserted between the current source and the connecting point of the main diode and said main switch, said auxiliary switch is connected in parallel to the serial branch formed by said resonant inductor and said main switch, said energy-feed device feeds out the residual energy of the resonant inductor when said auxiliary switch is turned off, and meanwhile feeds out the energy of the current s
Emerson Network Power Co., Ltd.
Morrison & Foerster / LLP
Sterrett Jeffrey
LandOfFree
Soft switching topological circuit in boost or buck converter does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Soft switching topological circuit in boost or buck converter, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Soft switching topological circuit in boost or buck converter will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3179617