Current-voltage converter and relative control circuit

The invention relates on the one hand to a current-voltage converter, in particular for high input voltages, comprising a primary side, the plurality of series Subsystems each having at least one transistor circuit breaker and respectively of a has its own associated transformer primary and a secondary side over which are coupled to a common load output subsystems and on the other hand a to a current-voltage converter, particularly for high input currents, comprising Primary side, with at least one respective plurality of parallel connected partial systems Transistor circuit breakers and in each case a separate associated transformer primary winding comprises, as well as a secondary side, over which the partial systems to a common Load output are coupled and an associated control circuit, comprising a Voltage regulator with voltage comparator and voltage amplifier and a current regulator with current comparator and current amplifier and a between the voltage regulator and current regulator arranged corrector.

In known from the prior art voltage transformers for high input AC voltages or dc voltage an intrusion of a peak value of the rectified arranged at a voltage directly at the output of a rectifier Capacitor with very large capacity. Consequently, had very expensive charging circuits with summons via for example a resistor and subsequent lock-up with Contactor contacts are realized.

Even so-called "double booster" topologies are known, with an intermediate circuit having an electrolyte-Kodensator, so that this or the upstream network when Intrusion of the high input voltage due to the feedthrough without short-circuit current limiting is charged. Therefore, this capacitor has on the peak voltage at the input be designed, which is higher than the regulated output voltage of the booster.

Also occur in the control of high input voltages and currents with respect to the Components used to problems. So must the semiconductors such as transistors used and diodes at the maximum input voltage or current to be adjusted and the Transformers used must both defined benefit in terms of voltage to the to processing input voltage to be adjusted, which is not acceptable and interturn Winding stresses.

In known transducers, the power transistors used as switching elements, the permissible input voltage by the voltage capacity of the power transistor type used limited. In a series / parallel connection of multiple, synchronously clocked Transistors, the problem of the voltage / current sharing, including, for example, affixing lossy RCD line branches stretch parallel to the transistor switch is known.

In DE 44 14 677 A1 a primary clocked voltage converter is proposed, whose Primary side of a plurality of serially connected partial systems to one another is established, the each include a transistor power switch arrangement, which each have their own Transformer primary winding is associated, which on the secondary side of the transformer are coupled to a common load output. The coupling effect on the Transformer winding voltage automatic, dynamic and quasi lossless Voltage between the partial systems under load.

In this embodiment, the transformer windings are secondary side "hard" -parallel connected. This results in the disadvantage that asymmetries to not current-limited perform dynamic transients, but only cause the balancing.

This circuit arrangement is encumbered with the disadvantage that if transducers AC input an intrusion of Spitz value of the rectified voltage a right at the exit of a rectifier arranged capacitor with very large Capacity is done and all of these forward converter topologies, none of the input voltage waveform Allow customized power consumption (Power Factor Correction PFC).

The present invention is therefore based on the problem, a converter for high to provide input voltages or currents are available, which has a simple structure and whose voltage or current balancing is improved.

The problem, in a converter, particularly for high input voltages, according to the invention achieved in that the series-connected subsystems comprises a branch with an input inductance and the at least one transistor circuit breaker comprising, wherein the inductors at least temporarily over the corresponding transistor circuit breakers electrically connected in series to the input voltage and a voltage balancing between cause the subsystems and in each case one output of the subsystems with each of Transformer primary winding is connected as isolating transformer to the power supply.

The problem is with a converter, in particular for high input currents, according to the invention achieved in that the parallel-connected subsystems comprises a branch with a input-side inductance and the at least one transistor circuit breaker comprising, the at least temporarily electrically over the corresponding transistor power-switches parallel to input voltage U_e lies and a current balancing between the subsystems causes and that one output each of the subsystems with each of the transformer primary winding connected as isolating transformer for power supply.

This topology results in a - in contrast to the known systems - current supply in the transformer. This means that each primary winding its power in flow concept transfers and thus imprinted on the secondary load.

Through time-synchronized activation of all arranged in the subsystems transistor circuit breaker each subsystem operates with a part of voltage or a partial flow, adjusted by the from the input voltage U_e or input current I_e divided by the number N of results in series or parallel connected partial systems. In this respect, both for the interpretation the transistors circuit breakers as well as the interpretation of such inductors Choke coils and transformers separator commercially available components are used, the not have to meet high-voltage requirements. This reduces costs by considerably. The main difference from the circuit configuration of the prior art is, that the current / voltage balancing on the input side and the primary side Inductance or choke coil of each subsystem takes place. Provided, that all reactors temporarily parallel in series or the same having inductance and a synchronous Ansteuem ensures falls on each for a certain period from current-carrying inductor on the one hand in a series circuit the same voltage drop, so that also the voltage applied via the switching elements voltage an N-th part of the input voltage U_e corresponds on the other hand falls in parallel an equal current component, so that the current flowing through the switching elements Currents meet one Nth part of the input current.

In a particularly preferred embodiment it is provided that the partial systems as SEPIC converter or regenerator are formed, wherein at least a transducer, preferably the reference potential (ground) connected transducer, connected to only one control circuit is assigned to the output signal with an all-transistor circuit breakers Drive circuit is connected.

In another particular embodiment, it is provided that the control loop with a the supply voltage circuit connected for sensing the voltage and / or the has mains frequency and forwards corresponding signals to the control circuit, so that the Voltage converter as a function of the input voltage as either DC converter or as AC converter operates with PFC analysis. By the use of the Power line associated detection circuit is a large field of application of the voltage converter allows. This allows the voltage converter system particularly for railway applications on at least four UIC voltages (1000 VAC 16 Hz 2/3; 1500 VAC 50 Hz; 1500 VDC; 3000 VDC) are operated.

The novel voltage conversion system is therefore able to adapt to different input voltages and / or adjust frequencies with the current consumption. Also, it is possible, that control parameters can be set to the respective nominal voltage.

For PFC analysis is provided that at least one further input side with the Inductor magnetically coupled inductor associated with a measuring element such as a shunt, at which an output current I_A proportional size I_A', Preferably DC size -abgreifbar is. Again, in turn results in the advantage that a PFC control at any AC input voltage is possible. The measuring element is preferably in the arranged associated subsystem with reference potential. The size I_A'Can also be an AC component have proportional to the input current I_e , that is a half sine wave function takes place.

Another advantage of using SEPIC converters in the system presented here voltage transformer is due to the fact that the otherwise usual primary storage capacitor at the output of the rectifier or the intermediate circuit on the low voltage side or is transformed secondary side and charged there short circuit current regulated. This the otherwise existing storage capacitor from the primary direct access of the input voltage withdrawn. For this reason, can be dispensed with electrolytes at the input (High-voltage circuit) and the electrolytes are transformed into the secondary circuit (low voltage circuit). In the secondary circuit cost electrolytic capacitors can be used.

-addressing by the input-side series or parallel connection of the isolation transformers Converter can be adapted even to 1 / N times the total output power the converter, where N is the number of series or parallel connected partial systems.

The winding tension and the winding current of each power isolation transformers can be designed correspondingly smaller.

In a preferred embodiment it is provided that the output voltage of Current-voltage converter system is adjustable for different output voltages. This is particularly due to the activation of the disposed in the sub-systems transistor power switch causes. There is also the possibility of a primary winding on a Core assign multiple secondary windings of different turns.

It is contemplated that the information contained in the sub-systems transistor power switch via are arranged on a common core transformer controlled, whereby a time-synchronized Driving the in series or parallel transistor circuit breaker is ensured. Furthermore, it is provided that the primary winding of the isolation transformer is coupled through a diode to a respective output of the SEPIC converter. This ensures that reverse currents of the isolating transformer no negative affect the SEPIC converter, and the current-transformer-free separation can demagnetize.

Furthermore, it is provided that the primary windings on a common core be wrapped and operate on a secondary winding.

According to the invention further comprises a control circuit for a current-voltage converter proposed comprising a voltage regulator with voltage comparator and voltage amplifier and a current regulator with current comparator and current amplifier and a between Voltage regulator and current regulator arranged corrector.

The control circuit includes a circuit for detecting the voltage and / or frequency on, wherein the switching circuit is connected to a sampling circuit with a Input to output voltage and one with an output to the first input Voltage comparator is connected and the voltage regulator output side is connected to a preferably multiplizierendem D / A converter, which in turn with a second input is connected to an output of the circuit and on the output side with is connected to an input of the current comparator of the current regulator.

By detecting mains voltage and frequency of the control loop can apply to different Input voltages and / or frequencies can be adjusted. The corresponding Control parameters are provided by the circuit available. A PFC analysis can thus in any AC input voltage (amplitude range and frequency) be performed. Alternatively, the rectified input voltage (after are rectifiers) scanned or captured.

In order to ensure an accurate determination of the network voltage and the line frequency - the Mains voltage can be a DC voltage - the circuit as an integrated Circuit, preferably designed as a microcomputer or microcontroller. Dependent on the determined network parameter is a synthetic function with constant amplitude B (for DC input) or a pulsating sine function B _Max | sin (ω t) | (AC input) in phase and placed in synchronization with the power input is available, the actual the synchronized network frequency represents. The at the output of the voltage amplifier fitting error amplified voltage difference k_u x .DELTA.U_A may then with the output the Mikrocontrolers provided digital sine function are multiplied. For this purpose, the voltage amplifier of the D / A converter is connected downstream of the digital sine of the circuit is supplied. At the output of the D / A converter is a sine-modulated error-amplified voltage can be tapped off, which as a setpoint value for the downstream power control loop is available.

Advantage of the novel control circuit arrangement is that a correction due to input voltage changes is not necessary. In particular, the corrector does not require Correction as a function of the input voltage U_e Also of the loop supplied actual current I_Alst is independent of fluctuations of the input voltage U_e,

It is envisaged that in the circuit preprogrammed sine functions are stored, wherein the digital values ​​in the voltage amplifier downstream D / A converter are multiplied and offset.

It is also provided that the synthetic sine is generated in the circuit as a reference for a continuous undervoltage or overvoltage detection is used.

Furthermore, the control circuit is integrated in the circuit comparator circuit on synchronized the present at the output of the circuit synthetic sine to network with the becomes.

If a mains voltage on no zero crossings, ie it is a DC input voltage, so the circuit is a constant value B, so that the control loop works as a DC control circuit and a PFC analysis does not take place in this case.

Through the above measures, the application range of the voltage converter system be significantly enhanced so that especially in the railway sector at least four UIC voltages (1000 VAC 16 2/3 Hz, 1500 VAC 50 Hz, 1500 VDC, 3000 VDC) or 48/60/110 / 220V DC and 110/234 VAC 60/50 Hz networks are manageable as Einspannungsbereichswandler. There the converter or regenerator permits very wide input voltage ranges, the Problem if the DC input voltage or AC input voltage with different Frequency achieved by the aforementioned approach, so that all four voltage ranges plus processed tolerances (+/- 30%) and long-term transients in an input voltage range can be. And DC input voltages with a particularly high AC voltage component preferably without peak currents are manageable. It is also Possibility that some of the control parameters to the nominal voltage can be preset (Ton-time).

Verfahrensmäßg the invention is characterized in that the primary subsystems in non-pulsating current operation are operated and the first time such a cascading Subsystems occurs. The subsystems are namely to "choke Reviewed" Topologies that are not stromlückend towards the entrance. Also according to the invention the PFC analysis of cascaded subsystems stage performed on only one subsystem, However, whereby the overall system PFC-rated.

In procedural terms is a return of control variables or monitoring functions with consuming potential-isolating measures unnecessary. This is achieved, that the output current than average-size on the primary side is measurable. Also, the Output voltage primary side during T_Off -time At the primary-side transformer winding be measured. Advantageously, the input voltage U_e during T_On-Time are measured on the secondary side to a secondary winding.

A correction of the control circuit on the input voltage U_eAs in the control circuits is known in the prior art, in the control circuit according to the invention dispensed with, since the line voltage / input voltage is determined by the circuit, and the output current proportional size regardless of input voltage fluctuations is.

Further, a current-voltage converter according to claim 25 with an independent presented character invention, the primary side has substantially the structure of a subsystem having the cascaded current-voltage converter already described, but output side multiple outputs having separate secondary windings on a common core are supplied with current from the primary winding. Due to the current supply the isolation transformer determine the output voltages of multiple outputs Only from the winding turn ratio of primary to secondary winding. The individual streams are divided according to the internal resistance of the load on the individual Outputs. Therefore, the output voltages are even under changing load currents constant.

Here too, we run the current-voltage converter in the non-pulsating current operation. The output variables are in turn the primary side and measured the above-described supply control loop.

Alternatively, an auxiliary winding or a secondary winding and / or the primary winding even be formed as a measuring coil to signals for the control circuit available deliver.

Further details, advantages and features of the invention result not only from the Claims and in the features they contain - singly and / or in combination - but also from the following description of preferred to be taken by the figures Embodiments.

Show it:<dl tsize="6"><dt>Fig. 1</dt><dd>a cascaded current-voltage converter with three primary side in series -connected subsystems, said subsystems configured as a SEPIC converter are,</dd><dt>FIG. 2</dt><dd>a current-voltage transformer having three primary side parallel Subsystems,</dd><dt>Fig. 3</dt><dd>a control circuit arrangement for at least a subsystem of the voltage converter system according to FIG. 1 or FIG. 2 and</dd><dt>Fig. 4</dt><dd>a current-voltage converter with multiple outputs, the secondary side.</dd></dl>

Fig. 1 shows a current-voltage converter 10, the comprehensive via a diode D1 to D4 Rectifier 12 with a mains voltage U_network connected is. The mains voltage U_network lies In this embodiment, typically in the range 1000 to 1500 VAC, and, a frequency from 16 2/3 Hz to 400 Hz have. Also, input voltages in the range of 1500 VDC to 3000 VDC possible. At the output of the rectifier 12 is in the here Illustrated embodiment, a sinusoidal pulsating, half-wave-shaped AC input voltage U_e to that constant in a means of the voltage converter 10 output voltage U_A is converted.

The current-voltage converter 10 includes a primary side 14, the plurality of series Subsystems 16, 18, 20, each having at least one transistor circuit breaker T1, T2, T3 have. The subsystems 16, 18, 20 are in the embodiment shown here configured as SEPIC converters or regenerators, whose output is labeled a primary winding TP1, TP2, TP3 an isolating transformer TR1, TR2, TR3 is. The isolating transformers TR1, TR2, TR3 respectively have secondary coils TS1, TS2, TS3 on which a secondary side 22 of the voltage converter 10 to a common Load output 24 are coupled.

Below is an example of the construction of a SEPIC converter based subsystem 20 described. The subsystem 20 includes a SEPIC converter 26, a primary side Input 28 to the inductor as the input choke is connected L20.1, which a capacitor 30 and a diode 32 to a first terminal 34 of the transformer primary TP3 is connected. Another terminal 36 is connected to a primary side Output 38 of SEPIC converter 26 connected. Between the entrance-side throttle L20.1 and capacitor 30 is a joint 40 which Vorschaltnetzwerk a 42 connected to a first terminal 44 of the transistor power switching element T3 is. Another terminal 46 of the transistor power switch T3 is connected to the Output 38. A control input 48 of the transistor power switch T3 is about a secondary winding of a transformer 50 connected to the output 38th Between the Capacitor 30 and the diode 32 is a junction 52, which via a second Inductor L20.2 and a resistor 56 as shunt is connected to the output 38th In parallel to the primary-side transformer winding TP3 is a relief network value as Series combination of capacitor 58 and resistor 60 is arranged.

On the secondary side, the secondary winding of the isolation transformer TR3 TS3 with a peak rectifying circuit 62 consisting connected from the diode D5, at whose output a Capacitor 64 is. The secondary winding TS2 is also a rectifying circuit 66 downstream, at whose output a capacitor is 68th The same applies for the secondary winding TS1, a rectifying circuit 70 is connected downstream, at whose output a Capacitor 72 is. The secondary side 22 consists essentially of three secondary systems 74, 76, 78, each consisting of the secondary transformer winding, the associated and associated rectifiers and the output capacitor. The secondary systems 74, 76, 78 are connected electrically in parallel and form an output 80 to which via a filter network 82, the regulated output voltage U_A can be tapped. capacitors 64, 68,72 may be interpreted in a large capacity as a single common capacitor will.

Preferably, the windings of isolating transformers are on a separate transformer core However, 84, 84 ', 84 "respectively. Alternatively it is possible, the windings with a corresponding ratio of the voltages and currents on a common core to arrange.

with through the primary-side series connection of the regenerators or SEPIC converter Isolation reduces the voltage drop across a transistor circuit breaker T1, T2, T3 Voltage to one third of the input voltage U_e, For this reason, Transistors are used with commercial electric strength. Through time-synchronized Driving the primary-side sub-systems 16, 18, 20 via the transformer 50, 50 ', 50 is " each stage to a third of the input voltage U_e, To time-synchronized to Ansteuem reach driving windings of the transformers 50, 50 ', 50 "of the joint on a magnetic core arranged. Alternatively, however, there is the possibility, the drive windings form as a separate transformer, especially at very high input voltages.

In driving the transistor power switches T1, T2, T3, a current flows from the positive Pole 86 of the rectifier 12 via an input inductor L16.1 the subsystem 16, a Vorschaltnetzwerk 42 "and the transistor circuit breaker T1, as well as the input inductor L18.1 that Snubbernetzteil 42 'and the transistor power switch T2 as well as the Input inductor L20.1 which Vorschaltnetzteil 42 and transistor circuit breaker T3 to the negative pole 88 of the rectifier. Since the current through the input inductor L20.1, L18.1 and L16.1 is identical, is - same inductances of inductors and synchronous Activation of transistor switching elements T1, T2, T3 provided - at each choke coil L16.1, L18.1, L20.1 fall the same voltage, thereby also to the transistor circuit breakers T1, T2, T3, an equal voltage drop is set.

Parallel to the inputs of the respective subsystems 16, 18, 20 lie at the DC input Capacitors 90, 90 ', 90 ", on each of which only 1/3 of the input voltage U_e drops. in the the present case is the otherwise conventional very large storage capacitor to the primary withdrawn dirkten access the input voltage and the low voltage or secondary side transformed and charged there short circuit current regulated.

In FIG. 2, a current-voltage converter 92 is illustrated coupled to a rectifier 94 the diodes D6 - D9 with mains voltage U_network connected is. In this embodiment, is the line voltage U_network typically in the range from 110 to 234 VAC or 28 - 48 VAC and can have a frequency of 16 2/3 Hz - 400 Hz exhibit. Also, power supply voltages the outside 4 - 72 or 14.4 to 154 VDC possible. The current-voltage converter 92 is particularly for high input currents I_e or output currents I_A designed.

The current-voltage converter 92 includes a primary side 96, a plurality of parallel-connected Subsystems 98, 100, 102, each having at least one transistor circuit breaker T4, T6, T7 have. The subsystems 98, 100, 102 are in the illustrated here Embodiment configured as SEPIC converters or regenerators, whose output each having a primary winding TP4, TP5, TP6 an isolation transformer TR4, TR5, TR6 connected is. The isolating transformers TR4, TR5, TR6 each have secondary coils TS4, TS5, TS6 on the one hand via a secondary side 104 of the voltage-current converter 92 to common load output 106 are coupled.

The structure of the sub-systems 98, 100, 102 substantially corresponds to the sub-systems 16, 18, 20, which have been described with reference to FIG. 1 in detail. By the primary-side Parallel connection of the Regenaroten or SEPIC converters 98, 100, 102 with the potential isolation reduces the current flowing through a transistor circuit breaker T4, T5, T6 Stream to one third of the input current I_e, For this reason, transistors common power strength can be used. Through time-synchronized activation of primary-side partial systems 98, 100, 102 flows by activation transmitters 108, 110, 112 through each stage one-third of the input current I_e, To time-synchronized activation to reached, the activation transmitters 108, 110, 112 in the parallel circuit described herein on a common core. The activation transmitters 108, 110, 112 can also (Not shown) as an electronic semiconductor power drivers be formed. Subsystems 98, 100, 102 have on the input side inductors L 98.1, L 100.1, 102.1 L, which the transistor power switch at least temporarily in parallel with the input voltage U_e lie and thus bring about a current balancing of the overall system.

The regulation of the current-voltage converter is based on the control circuit of Fig. 3 are explained.

In Fig. 3 is a control circuit arrangement for driving at least one subsystem 16, 18, 20or 98, 100, 102 of the current-voltage converter 10 or 92 in accordance with Figs. 1 or 2. The control circuit 200 has its input side a voltage comparator 202 which with a first input 204 with a reference voltage U_ARef and to a second input 206 via a sensing circuit 208 such as sample and hold circuit or continuous Measure the output voltage U_A for tapping an actual voltage U_Alst connected is. The output voltage U_A is via an unillustrated measuring element at the output 24 of the measured current-voltage converter or via the load voltage U_A'At the primary Transformer winding TP1 - TP6 during the T_OFF-Phase.

An output 210 of the comparator 202 is connected to an input 212 of an amplifier 214, a from actual voltage U_Alst and reference voltage U_ARef Differential voltage formed .DELTA.U_A to strengthen. At an output 216 of the amplifier 214 is an error amplified voltage K_U x Δ U_A to which an input 218 of a multiplying D / A converter 220 is supplied. A further input 222 of the D / A converter 220 is connected to a Output 224 of a circuit, preferably Mikrocontrolers 226.. The microcontroller 226 is, in turn, via a feed line 228 with a power line or mains voltage with U_network connected. Furthermore, the micro-controller 226 and an output 230 a trigger line 232 connected to an input 234 of the sampling circuit 208th

An output 236 of the D / A converter 220 to which a target current I_ASoll bears, is a Input 238 of a comparator 240 connected. A further input 242 of the comparator 240 is connected via a lead 138 to the shunt 56 in the branch of the inductor to 220.1 Tap an output current I_A proportional size I_A' connected. An output 244 of the comparator is connected to an input 246 of a current amplifier 248th on a Output 250 of the amplifier is an amplified current difference K_I x .DELTA.I_A to which a Control unit 252 is supplied to and forms a control variable. The drive unit has also an input 254 for the mains and input voltage to the T_ONcontrol, and an output 256 for driving the transistor circuit breakers T1 and T6 on Drive transformer 50, 50 ', 50 ", 108 - 112. The size K_I x .DELTA.I_A the T_OFF -Time the transistor circuit breakers T1 - T6 regulated or controlled. is also without U / I controller by T_ONManagement and to target the T_OFF-voltage As DC-size a quasi constant Output voltage with sinusoidal current consumption in AC power and alternating Entrance or exit load achieved.

About the input line 228 determines the micro-controller 226 on the one hand, the input line voltage U_network and on the other hand, the grid frequency f_network , With DC voltage as mains voltage the frequency f_network = 0 detected. Any desired frequencies, preferably f = 2/3 16, 50 or 60 Hz can be detected. Due to the determined mains frequency is in the Microcontroller 120 a syntetische, ideal pulsating (rectified) sine function stored and generated which is synchronized with the mains frequency and a constant amplitude B_Max having.

After detection and storage of the time base the processing starts with a zero crossing trigger and synchronize it with other zero crossings. Synchronization pulses, which lie between the mathematical zero crossings are due to possible Interference disappears.

The generated sine wave is supplied via the output 224 to the input 226 of the D / A converter 220 output. At the same time with a synchronization pulse to each Half-wave zero crossing is present, triggered, the scanning circuit 208th In the D / A converter 220 the error amplified voltage difference is now K_U x .DELTA.U_A with the synthetic Sinusoidal curve Bmax x | sin (.omega.t) |, which is located to the mains voltage in phase multiplied. At the Output is therefore a sine-rated voltage error amplified size at which a target current I_ASoll T6 is available - for activating the transistor circuit breaker T1. In contrast to known control circuits there is no need additional correction element, as by measuring the output current at the primary side throttle branch size to Available, the U of long-term fluctuations of the input voltage_e is independent but the waveform of the rated frequency follows (PFC).

Due to the generated in the microcontroller synthetic sine function this can also be used as a reference for under- and overvoltage detection. In the the microcontroller generated sine function by means of a comparator circuit for Network are synchronized. Detects the microcontroller 226 that the input voltage a DC power is, as a constant voltage B is output at the output 224, so that a PFC analysis omitted.

With respect to the output voltage actual value U_Alst it should be noted that this the Trigger Sine zero crossing retrieved, stored in the sample and hold circuit 208 and with the reference value U_ARef is compared.

The described system of current-voltage converters 10, 92 and control circuit according to the invention 200 is used in particular in the railway sector at four UIC voltages, such Example 1 000 VAC 16 Hz 2/2, 1500 VAC 50 Hz, 1500 VDC and 3000 VDC for use. Since the voltage converter or regenerator a wide input voltage range permits, the issue of whether the AC input voltage or input DC voltage or which frequency has the AC input voltage, by the above-indicated resolved features. However, all four areas and tolerances (+ - 30%) and long-term transients are processed in an input voltage range.

The FIG. 4 is a current-voltage converter 400 with an independent inventive character to remove. The current-voltage converter 400 includes a rectifier 404 to a Mains voltage U_network lying primary side 402 and a secondary side 406, the plurality of d. h. multiple, preferably three outputs 408, 410, 412 with the output voltages U_A1. U_A2, U_A3,

In parallel to output terminals 414, 416 of the rectifier 404 is a capacitor 418 an input voltage U_e is applied for the current-voltage converter 400th With the Connection 414 is a primary inductance as choke coil L420.1 connected, via a capacitor 422 and a diode 424 to a first terminal 426 of a primary side Winding TP7 einers isolation transformer TR is connected. With a connection 428 is the primary-side winding TP7 to the input terminal 416 of the rectifier 404 connected. is a connection point between the choke coil and the capacitor 422 L420.1 430, via a snubber network 432 and a transistor power switch T7 is connected to the terminal 416th A control terminal 434 of the transistor power switch T7 is connected via a secondary winding 436 of a drive transformer 438 with the terminal 416 connected.

A lying between the capacitor 422 and the diode 424 junction 440 is via a second inductor, such as inductor L and 420.2 to a lying in series Measuring element as shunt 444 also connected to the terminal 416th The secondary side multiple outputs 408, 410, 412 each have a secondary winding TS7.1, TS7.2, TS7.3, which together with the primary winding on a common core 446 TP7 are arranged. The secondary windings TS7.1, TS7.2, TS7.3 are each a Rectifier diode 448, 450, 452 connected to an output capacitor 454, 456, 458, at which the output voltage U_A1, U_A2 and U_A3 rest.

To control the current-voltage converter 400 may be the one described with reference to Fig 3 Control loop can be used. Also, the current-voltage converter 400 is characterized from that a return of control variables or monitoring functions of the secondary side Sizes is not required. This is in particular possible because the Output voltage primary side during T_Off-time At the connection 426 of the primary winding TP7 and the output current (Average size) on the primary side of the measuring element 440 is measurable. The input voltage may occur during T_On-Time Measured on the secondary side will.