Electric power conversion systems – Current conversion – With voltage multiplication means
Reexamination Certificate
2002-06-27
2003-11-18
Riley, Shawn (Department: 2838)
Electric power conversion systems
Current conversion
With voltage multiplication means
Reexamination Certificate
active
06650555
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a switched-capacitor-type stabilized power circuit in which switching elements are respectively provided before and after a capacitor so as to carry out step-up operation by switching a connection of the capacitor and an inputted direct-current power source between series and parallel, and in particular to a switched-capacitor-type stabilized power circuit using batteries as the inputted direct-current power source.
BACKGROUND OF THE INVENTION
FIG. 5
is a block diagram showing an electrical arrangement of a typical switched-capacitor-type stabilized power circuit
1
adopting a conventional technique. The switched-capacitor-type stabilized power circuit
1
generally has an arrangement such that a step-up capacitor c
1
, an input smoothing capacitor c
2
, an output smoothing capacitor c
3
and voltage-dividing resistors r
1
and r
2
for an outputted voltage feedback are externally provided to a control circuit chip
2
.
The step-up capacitor in the switched-capacitor-type stabilized power circuit
1
has a single stage arrangement denoted by a reference code cl. In the control circuit chip
2
, a pair of switches s
1
and s
2
is provided before the capacitor c
1
, and a pair of switches s
3
and s
4
is provided after the capacitor c
1
. The control circuit
3
turns on/off the pair of switches s
1
and s
2
at the same time, and turns on/off the pair of switches s
3
and s
4
at the same time. Further, the control circuit
3
makes the pair of switches s
1
and s
2
, and the pair of switches s
3
and s
4
to carry out a reverse operation each other (the pair of switches s
1
and s
2
is on when the pair of switches s
3
and s
4
is off, and the pair of switches s
1
and s
2
is off, when the pair of switches s
3
and s
4
is on.)
In a charge-period, the pair of switches s
1
and s
2
is on, and an inputted direct-current voltage vin from a battery is applied to the capacitor c
1
after being smoothed by the capacitor c
2
. Thus, the capacitor c
1
is charged with the inputted direct-current voltage vin. In a discharge period, the pair of switches s
3
and s
4
is on, and the inputted direct-current voltage vin and a charged voltage of the capacitor c
1
are joined together. Therefore, a voltage of 2×vin is supplied to the capacitor c
3
. This voltage is smoothed by the capacitor c
3
, and is outputted as an outputted voltage vo. In this manner, a step-up operation to double the voltage is carried out.
The output voltage vo becomes a feedback voltage vadj after being divided by the voltage-dividing resistors r
1
and r
2
, and is compared to a reference voltage vref from a reference voltage source
4
by a hysteresis comparator
5
, and a result of the comparison is inputted to the control circuit
3
. The control circuit
3
makes the pair of switches s
1
and s
2
and the pair of switches s
3
and s
4
to carry out the switching operation until the feedback voltage vadj reaches to the reference voltage vref, and makes the pair of switches s
1
and s
2
and the pair of switches s
3
and s
4
to stop the operation when the feedback voltage vadj reaches to the reference voltage vref. As described, the outputted voltage vo stays constant regardless of a load.
In the stabilized power circuit
1
having the foregoing arrangement, the inputted direct-current voltage vin is supplied from a constant voltage circuit
6
as a power source to the control circuit
3
, and also to the hysteresis comparator
5
which control the switching operation. Accordingly, in the case of the input from a battery, when the voltage of the battery decreases to a voltage smaller than the operation voltage of the control circuit
3
or the like, the control operation does not work properly, and the outputted voltage vo decreases due to an increase of on-state resistance of the switching elements which are included in the switches s
1
, s
2
, s
3
and s
4
.
SUMMARY OF THE INVENTION
The present invention is made to provide a switched-capacitor-type stabilized power circuit capable of carrying out a proper step-up operation even when an inputted direct-current decreases.
In order to solve the foregoing problems, the switched-capacitor-type stabilized power circuit of the present invention includes;
switching elements provided before and after a capacitor;
a control section which controls the switching elements, for switching a connection of the capacitor and an inputted direct-current power source between series and parallel, so as to carry out step-up operation;
a feedback comparator which gives feedback of information relating to an outputted voltage to the control section, so as to stabilize the outputted voltage;
a constant voltage circuit which supplies power to the control section; and
switching means for selecting an inputted direct-current voltage at rising of the inputted direct-current voltage, and selecting an outputted voltage after the rising of the outputted voltage, for a voltage supplied to the constant voltage circuit in response to the feedback comparator.
With the foregoing arrangement, the switched-capacitor-type stabilized power circuit selects the inputted direct-current voltage at rising of the inputted direct-current voltage and selects the outputted voltage after the rising of the outputted voltage for the voltage supplied to the constant voltage circuit which supplies power to the control section by using a signal from the feedback comparator which gives feedback of information relating to the outputted voltage to the control section so as to stabilize the outputted voltage.
Accordingly, once the step-up operation is carried out in a state where the inputted direct-current voltage is at or greater than the operation voltage of the control section, it is possible to maintain a proper operation even when the inputted direct-current voltage decreases. Further, a signal of the hysteresis comparator is used for the switching for an input of the constant voltage circuit which supplies the power source to the control section. Thus, the circuit can be simplified.
Further, in order to solve the foregoing problems, the switched-capacitor-type stabilized power circuit of the present invention includes;
switching elements provided before and after a capacitor;
a control section which controls the switching elements, for switching a connection of the capacitor and an inputted direct-current power source between series and parallel, so as to carry out step-up operation;
a constant voltage circuit which supplies power to the control section; and
switching means for selecting the inputted direct-current voltage at rising of the inputted direct-current voltage and selecting the outputted voltage after the rising of the outputted voltage and selecting a off-state when the outputted voltage is higher than a predetermined level, for the voltage supplied to the constant voltage circuit.
With the foregoing arrangement, the switched-capacitor-type stabilized power circuit selects the inputted direct-current voltage at rising of the inputted direct-current voltage and selecting the outputted voltage after the rising of the outputted voltage and selecting the off-state when the outputted voltage is higher than the predetermined level, for the voltage supplied to the constant voltage circuit which supplies power to the control section.
Accordingly, once the step-up operation is carried out in a state where the inputted direct-current voltage is at or greater than the operation voltage of the control section, it is possible to maintain a proper operation even when the inputted direct-current voltage decreases. Further, under light-load condition and when the outputted voltage is higher than the predetermined level, there will be no troubles if the step-up operation by the switched-capacitor stops. Thus, in that condition, the power supply to the constant voltage circuit is cut off, and the operation of the control section is stopped. Therefore, power consumption can be reduced.
Further, a step-up circuit may be provided for carrying out the ste
Fujita Toshiyuki
Inaba Katsumi
Suzuki Tomohiro
Harness & Dickey & Pierce P.L.C.
Riley Shawn
Sharp Kabushiki Kaisha
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