Non-insulating DC—DC converter

Details Non-insulating DC—DC converter Non-insulating DC—DC converter

2000-02-15

2001-03-06

Han, Jessica (Department: 2838)

Electricity: power supply or regulation systems

In shunt with source or load

Using a three or more terminal semiconductive device

C323S225000, C323S285000

Reexamination Certificate

active

06198259

ABSTRACT:

BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a non-insulating DC—DC converter for use in an electric vehicle, and more particularly, to a non-insulating DC—DC converter for use in charging a low-voltage battery with power from a high-voltage battery.
FIG. 7
shows an example of a conventional non-insulating DC—DC converter.
The non-insulating DC—DC converter shown in
FIG. 7
comprises an input terminal
1
b
and an output terminal
7
a
. A check diode
12
, a MOSFET
2
, and a choke coil
4
are connected in series between the input terminal
1
b
and the output terminal
7
a.
In addition, a diode
3
and a capacitor
5
are connected in parallel between the input terminal
1
b
and the output terminal
7
a
. The input terminal
1
b
has a battery terminal
1
a
for a high-voltage battery
1
connected thereto via an input cable
1
c.
A control circuit
6
has a terminal connected to the high-voltage battery
1
, a terminal connected to a gate of the MOSFET
2
, and a terminal connected to one end of the capacitor
5
. The output terminal
7
a
is connected to a low-voltage battery
7
.
In such a configuration, the control circuit
6
applies a pulse voltage to the gate of the MOSFET
2
to control on/off operation of the MOSFET
2
in such a manner that a power from the high-voltage battery
1
is charged into the low-voltage battery
7
.
In addition, if the control circuit
6
fails and provides an overvoltage to one end of the capacitor
5
, the MOSFET
2
is turned off to prevent an output of the overvoltage. Furthermore, the inflow of an overcurrent is hindered by the check diode
12
.
In the above conventional non-insulating DC—DC converter, however, if the MOSFET
2
is damaged due to an overvoltage or another reason, an overcurrent from the high-voltage battery
1
flows into the inside of the non-insulating DC—DC converter via an input cable
1
c
. When this occurs, the input cable
1
c
may be damaged by heat or the internal elements in the non-insulating DC—DC converter may be damaged, both of which are problems.
In addition, if an electronic equipment is connected to the non-insulating DC—DC converter, the internal elements in the electronic equipment may be damaged.
Furthermore, if the input cable
1
c
is connected to the negative-terminal side of the battery
1
as shown by the dotted line in the drawing, a reverse current from the low-voltage battery
7
may damage the MOSFET
2
and the check diode
12
.
Furthermore, if the low-voltage battery
7
side is reversely connected, a reverse current from the low-voltage battery
7
causes a short-circuit current to flow via the diode
3
, which may be damaged.
In addition, if the high-voltage battery
1
side is reversely connected, a short-circuit current may flow via the diode
3
to damage the MOSFET
2
and the check diode
12
.
The present invention is provided in view of the above problems, and is intended to provide a non-insulating DC—DC converter that can prevent the internal elements from being damaged due to overvoltage or overcurrent, thus providing an appropriate power supply while also restraining costs.
SUMMARY OF THE INVENTION
To attain the above object, the present invention provides a non-insulating DC—DC converter for charging a low-voltage battery with a power from a high-voltage battery, which comprises a first semiconductor switching element for reducing a DC voltage from the high-voltage battery, a control circuit for controlling pulses relative to the first semiconductor switching element, a second semiconductor switching element provided on the output side of the first semiconductor switching element, a capacitor connected between the first and second semiconductor switching elements in parallel, and a first control circuit for detecting a voltage at one end of the capacitor and a voltage on the output side of the second semiconductor switching element and for turning off the second semiconductor switching element if an overvoltage occurs at the one end of the capacitor.
The converter may have a third semiconductor switching element provided on an input side of the second semiconductor switching element, controlled by the first control circuit and connected to the second semiconductor switching element in the reverse direction. If a current on the output side flows in the reverse direction, the first control circuit turns off the second or third semiconductor switching element having the same polarity as the reverse current.
The converter may have a third semiconductor switching element provided on an input side of the first semiconductor switching element, controlled by the second control circuit and connected to the first semiconductor switching element in the reverse direction relative thereto. If a current on the input side flows in the reverse direction, the second control circuit turns off the third semiconductor switching element.
The first control circuit may comprise a first drive power supply connected between the input side of the first semiconductor switching element and the second semiconductor switching element for driving the second semiconductor switching element, a second drive power supply connected between the input side of the first semiconductor switching element and the third semiconductor switching element for driving the third semiconductor switching element, a first detection circuit connected parallel to the output side of the second semiconductor switching element for detecting the connection status of the low-voltage battery and for driving the first and second drive power supplies if this connection is normal, and a second detection circuit connected parallel to the capacitor for detecting an overvoltage at one end of the capacitor and for stopping driving by the first drive power supply when any overvoltage is detected.
The third semiconductor switching element may be connected in series to the capacitor and turned on/off by a switch circuit. The first control circuit may comprise a first drive power supply connected between the input side of the first semiconductor switching element and the second semiconductor switching element for driving the second semiconductor switching element, and a third detection circuit connected parallel to the input side of the first semiconductor switching element. Upon detecting an input overvoltage, the third detection circuit may turn of f the third semiconductor switching element via the switch circuit, stop driving of the first drive power supply, and further turn off the first semiconductor switching element via the control circuit.
A first potential divider may be connected between the input and output of the first semiconductor switching element and in parallel. A second potential divider may be connected parallel to a diode connected parallel to the output side of the first semiconductor switching element. A maximum permissible voltage on the input side of the first semiconductor switching element may be determined by the first semiconductor switching element and diode and by the first and second potential dividers.
The first drive power supply may instantaneously be driven by a fourth detection circuit when a voltage sufficient to drive the second semiconductor switching element is detected. The second drive power supply may instantaneously be driven by a fifth detection circuit when a voltage sufficient to drive the third semiconductor switching element is detected.
The first to third semiconductor switching elements may be MOSFETs.
The non-insulating DC—DC converter constructed as described above prevents internal elements from being damaged due to an overvoltage or a reverse current. Namely, if an overvoltage occurs, the first control circuit turns off the second semiconductor switching element provided on the output side of the first semiconductor switching element. If the current on the output side flows in the reverse direction, the first control circuit turns off the second or third semiconductor switching element having the same polarity as the reverse current. If the

Affiliated with

Also associated with

Rating

Non-insulating DC—DC 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 Non-insulating DC—DC converter, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Non-insulating DC—DC converter will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2438620