Electric power conversion systems – Current conversion – Constant current to constant voltage or vice versa
Reexamination Certificate
2000-05-30
2001-01-30
Nguyen, Matthew (Department: 2838)
Electric power conversion systems
Current conversion
Constant current to constant voltage or vice versa
Reexamination Certificate
active
06181586
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention herein relates on one hand to a current-to-voltage converter, in particular for high input voltages, with a primary side, which comprises several serially connected partial systems including, respectively, at least one transistor circuit breaker and at least one separate associate transformer primary winding, and with a secondary side, over which the partial systems arc coupled into a common load output, and relates on the other hand relates to a current-to-voltage converter, in particular for high input currents, with a primary side, which comprises several parallel connected partial systems including, respectively, at least one transistor circuit breaker and at least one separate associate transformer primary winding, and with a secondary side, over which the partial systems are coupled into a common load output, and further relates to an associate closed-loop control circuit comprising a voltage regulator with voltage comparator and voltage amplifier and comprising a current regulator with current comparator and current amplifier, as well as a correction member located between the voltage regulator and the current regulator.
In the case of voltage converters for high alternate input voltages or direct voltage as known from prior art, a peak value of the rectified voltage is impressed on a high-capacity capacitor located directly at the outputs of a rectifier. Consequently, very expensive charge circuits with pre-charging capability had to be implemented, for example, by including a resistor and subsequent bridging with ground contacts.
Also, so-called “double-booster” topologies have been known; these comprise an intermediate circuit including with an electrolyte capacitor in such a manner that the latter or the upstream mains is subjected to a load when the high input voltage is impressed due to the feedthrough, without short circuit limit. Therefore, this capacitor must be configured for the peak voltage at the input, whereby this peak voltage is greater than the booster's regulated output voltage.
Furthermore, in controlling high input voltages and currents, problems occur concerning the components used. The semiconductors such as transistors and diodes used must be adapted to the maximum input voltage or current, and the transformers used must be adapted from the viewpoints of power, as well as voltage, to the input voltage to be processed, whereby unacceptable winding and coil voltages occur.
In the case of known converters, which use power transistors as switching elements, the permissible input voltage is limited by the load capability of the type of power transistor used. When several synchronously clocked transistors are connected in series and/or parallel, the problem of voltage and/or current balancing arises, one example of this being the connection of loss-prone RCD line branches parallel to the transistor break distance.
DE 4,414,677 A1 has suggested a primary switched voltage converter with a primary side composed of several serially connected partial systems, each including a transistor circuit breaker arrangement, whereby each of these systems is associated with a separate transformer primary winding, which, in turn, are coupled into a common load output over the secondary side of the converter. Due to the transformer winding voltage, this coupling effects automatic, dynamic and quasi loss-free voltage balancing between the partial systems under load.
In the case of this form of embodiment the transformer windings are connected “hard” parallel on the secondary side. This has the disadvantage that the absence of balances results in dynamic circulating currents—which are not current-limiting—but effect balancing.
Also this circuit layout has the disadvantage that, in the case of converters with alternating current input, a peak value of the rectified voltage is impressed directly on a high-capacity capacitor located directly at the output of a rectifier and that all of these flow-through converter topologies do not permit a power take-up (Power Factor Correction=PFC) adapted to the waveform of the input voltage.
SUMMARY OF THE INVENTION
Therefore, the problem to be solved by the invention herein provides a converter for high input voltages or input currents, said converter having a simple design and improving voltage or current balancing.
In accordance with the invention herein, this problem has been solved in the case of a converter, in particular for high input voltages, in that each of the serially connected partial systems comprises a branch with input-side inductance and at least one transistor circuit breaker, whereby the inductances are applied, at least temporarily, over the corresponding transistor circuit breaker electrically in series to the input voltage and result in voltage balancing between the partial systems, and whereby one output of each of the partial systems is connected with the respective transformer primary winding acting as isolating transformer for power supply.
In accordance with the invention herein, this problem has been solved in the case of a converter, in particular for high input currents, in that each of the parallel connected partial systems comprises a branch with an input-side inductance and at least one transistor circuit breaker which, at least temporarily, is connected electrically parallel to input voltage U
E
and thereby balances the currents between the partial systems, and that respectively one output of the partial systems is connected with respectively one transformer primary winding acting as isolating transformer for power supply.
As opposed to known systems, this topology results in the supply of power into the transformer. This means that each primary winding transmits its current in a flow-through manner and hence impresses it on the secondary load.
By time-synchronized activation of all transistor circuit breakers, each partial system works with a partial voltage or partial current, which is obtained by dividing the input voltage U
E
or the input current IE by the number N of the serially or parallel connected partial systems. In so doing, commercially available components can be used for the layout of the transistor circuit breakers, as well as for the layout of inductances such as reactance coils and isolating transformers, whereby these components need not comply with high-voltage requirements. This reduces costs considerably. When compared with prior art, the essential difference is that voltage and/or current are balanced over the input-side inductance or primary-side inductance or reactance coil of the corresponding partial system. Provided that all reactance coils, which are temporarily connected in series or parallel, exhibit the same inductance and synchronous activation is ensured, on one hand a proportional voltage drop occurs on each reactance coil carrying a current for a certain period of time, when the connection is in series, so that also the voltage applied over the circuit elements corresponds to a Nth portion of the input voltage U
E
, and on the other hand a proportional current drop occurs, when the connection is parallel, so that current flowing through the circuit elements corresponds to a N
th
portion of the input current.
In a particularly preferred embodiment the partial systems are configured as SEPIC converters or regenerators, whereby at least one converter, preferably the reference (connected to ground) converter, is connected with only one closed-loop control circuit, the output signal of which is supplied to a trigger circuit associated with all transistor circuit breakers.
In another particularly preferred embodiment the closed-loop control circuit includes a circuit, which is connected to line voltage for the detection of line voltage and/or line frequency, and sends corresponding signals to the closed-loop control circuit, whereby the voltage converter functions either as DC converter or as AC converter with PFC analysis, depending on the input voltage. By using a mains-connected detector, the voltage converter can b
Dennison, Scheiner Schultz & Wakeman
Nguyen Matthew
LandOfFree
Current-to-voltage converter and associate closed-loop... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Current-to-voltage converter and associate closed-loop..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Current-to-voltage converter and associate closed-loop... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2556643