Electric power conversion systems – Current conversion – Using semiconductor-type converter
Reexamination Certificate
2000-05-03
2001-04-24
Han, Jessica (Department: 2838)
Electric power conversion systems
Current conversion
Using semiconductor-type converter
C363S017000
Reexamination Certificate
active
06222750
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to an inductor-type converter having an inductor arranged between a first and a second node in the diagonal of an H-bridge topology that is operated with a supply voltage. The invention further relates to methods of operating the novel inductor-type converter.
Inductor-type converters make use of the effect that when a DC voltage is applied to an inductor, the current flowing through the latter rises with time linearly to a first approximation. If the voltage across the inductor is pulsed a specific output voltage is produced. Varying the duty ratio enables variation of the output voltage for a predetermined input voltage.
Step-up regulators, in which the output voltage may be greater than the input voltage, and step-down regulators, in which the output voltage may be less than the input voltage, are known in the pertinent art.
Such step-up and step-down regulators are disclosed in Stengl/Tihanyi “Leistungs-MOS-FET-Praxis” [Practical Power MOS-FETs], Pflaum Verlag Munich, 1992, pp. 176-77. A dedicated inductor is in each case necessary both for a step-up regulator and for a step-down regulator.
U.S. Pat. No. 5,552,694 discloses an inductor-type converter having an inductor which can be operated either as a step-up converter or as a step-down converter. That converter outputs an output voltage which is either greater or smaller than the input voltage.
SUMMARY OF THE INVENTION
The object of the invention is to provide an inductor-type converter circuit and a method of operating the circuit which overcome the above-noted deficiencies and disadvantages of the prior art devices and methods of the generic kind, and which, by means of a single inductor, can be operated both as a step-up regulator and as a step-down regulator that generates two voltages from a single voltage source, one of which voltages may be greater than the input voltage and the other of which may be less.
With the above and other objects in view there is provided, in accordance with the invention, an inductor-type converter, comprising:
a supply voltage having a positive pole and a negative pole;
a first node, a second node, and an inductor connected between the first node and the second node;
a first switching element connected between the first node and the positive pole of the supply voltage;
a first series circuit connected between the first node and the negative pole of the supply voltage, the first series circuit including a second switching element and a second capacitor connected to the second switching element via a junction point;
a third switching element connected between the second node and the negative pole;
a second series circuit connected between the second node and the negative pole, the second series circuit including a fourth switching element and a first capacitor;
a further switching element connected between the second node and the junction point between the second switching element and the second capacitor; and
an electronic control unit connected to each of the switching element, the electronic control unit outputting output signals for controlling the switching elements.
In accordance with an added feature of the invention, the switching elements are N-channel MOSFET switches having source terminals and bulk terminals, the source terminals of the second switching element and of the further switching element being connected to one another and the bulk terminals of the second switching element and of the further switching element being connected to the negative pole.
With the above and other objects in view there is also provided, in accordance with the invention, a method of operating the above-described inductor-type converter. The method comprises the following steps:
generating a predetermined, first output voltage available at the first capacitor by performing the following steps at least once:
turning on the first switching element and the third switching element until the inductor is charged with energy;
subsequently transferring the inductor energy to the first capacitor by turning the third switching element off; and
subsequently turning the first switching element off after the inductor energy has been transferred to the first capacitor or if the predetermined value of the first output voltage has been reached.
In accordance with an additional feature of the invention, the fourth switching element is turned on while the inductor energy is transferred (through the diode) to the first capacitor.
In accordance with another feature of the invention, a residual energy remaining in the inductor after the predetermined, first output voltage has been reached, is charged into the second capacitor via the further switching element.
With the above and other objects in view, there is also provided, in accordance with the invention, a further method of operating the above-outlined converter. The method comprises the following steps:
generating a predetermined, second output voltage available at the second capacitor by performing the following steps at least once:
turning on the first switching element and the further switching element and consequently charging the inductor with energy and charging the second capacitor;
subsequently turning off the first switching element;
subsequently charging the second capacitor by the inductor via the further switching element which is still in the on state, until the inductor charge has been transferred to the second capacitor or the predetermined value of the second output voltage has been reached; and
subsequently turning the further switching element off.
In an alternative method, the inductor-type converter is operated with the following steps to generate a predetermined, second output voltage available at the second capacitor by performing the following steps at least once:
turning on the first switching element and the third switching element and consequently charging the inductor with energy;
subsequently turning off the third switching element and turning on the further switching element to consequently charge the second capacitor with the inductor until the inductor energy has been transferred to the second capacitor
or the predetermined value of the second output voltage has been reached; and
subsequently turning off the first switching element and the further switching element.
A further method of operating the above inductor-type converter comprises:
maintaining the predetermined, second output voltage in the event of a failure of the supply voltage, by turning off the second switching element and the fourth switching element, transferring charge from the first capacitor into the inductor and the second capacitor, and subsequently turning off the fourth switching element for charging the residual inductor energy into the second capacitor.
The foregoing methods and variations may be combined. In a preferred implementation of the method, the various generating steps are performed alternately or in any desired order.
In accordance with a concomitant feature of the invention, the switching elements are controlled according to a program that is stored in the electronic control unit.
In summary, the objects of the invention are satisfied with the novel inductor-type converter which ensures that, as long as the supply voltage is available, both the energy required for the smaller voltage and the energy required for the larger voltage are drawn directly from the supply voltage source. After possible failure of the supply voltage source (autonomy time situation), the driving of the electronic switching elements is changed over in such a way that both voltages are preserved for a certain period of time, where the energy for the smaller of the two voltages can be drawn from an energy store assigned to the larger voltage.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in inductor-type converter, it is nevertheless not intended to be limited
Belau Horst
Swart Marten
Wagner Ekkehart-Peter
Greenberg Laurence A.
Han Jessica
Lerner Herbert L.
Siemens Aktiengesellschaft
Stemer Werner H.
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