DE4414677A1 - High voltage DC-DC converter - Google Patents

Abstract

A high voltage DC-DC converter has a transformer with a single secondary winding (ts) and cyclically switched transistors (s11 to s24) in the input circuit. The transformer has a number of separate primary windings(tp1,tp2) which are electrically in series and coupled magnetically in parallel to the secondary. However, there may be secondary winding allocated to each primary winding, in which case they are all feed the same output terminals. The four transistors in each primary circuit form a full bridge rectifier arrangement, controlled synchronously in pairs in push-pull mode. Instead, the primary circuits may comprise two transistors in a half bridge rectifier arrangement, again operated in push-pull mode.

Description

The invention relates to a primary clocked chip voltage converter, especially for high DC input voltages, according to the preamble of claim 1.

The advantages of using transistor circuit breakers, especially MOSFETs and IGBTs when used as a switch elements in such voltage converters are known. At on set of a single switching transistor for a switching the transistor will function in the blocked, non-conductive state Switching state with a voltage in the order of a voltage and above what is accordingly the to casual input voltage limited. To higher input voltages to cope with, it is therefore also known to have several oil sistor circuit breaker for a switching function in series to interconnect, then on an even span voltage distribution to pay attention to the different transistors is to prevent malfunction. To avoid this Difficulty has already been suggested, proportionately to provide complex control circuits for the transistors or a span parallel to the switching path of each transistor  switch on the symmetrical RC or RCD line branch. The latter measure for dynamic voltage symmetrization however requires corresponding component expenditure, has ohmic Losses and adversely affects the Schaltge dizziness.

These known measures are for example by C. Raulet et al. in a contribution "MISE EN SERIE de TRANSISTORS M.O.S.F.E.T. de PUISSANCE "to the conference" ELECTRONIQUE DE PUISSANCE DU FUTUR, TOULOUSE, 10-12 Octobre 90 ".

The invention is a technical problem of providing a primary clocked voltage converter of the aforementioned Type based, with the lowest possible circuit technology low cost loss symmetry is achieved for the transistor circuit breaker.

This problem is caused by a primary clocked voltage wall ler solved with the features of claim 1. The assignment a separate primary winding of the transformer for each primary-side, a corresponding input subsystem and its coupling on the secondary side ensure an automatic, equal moderate, dynamic and practically lossless voltage distribution on these subsystems. Because as soon as the voltage distribution in the operation of an even, symmetrical division deviates, the energy output of that transformer increases partly, whose primary winding in a subsystem with one he increased voltage value, while the energy output of a other transformer part, the primary winding of a part sy stem associated with reduced voltage decreases. When As a result, the voltage in the subsystem drops with the increased Voltage, while that of the subsystem with the low voltage rises again, causing another sets symmetrical voltage distribution.

The mutual coupling of the primary windings over the second The fermentation side can be done in different ways, for example  in an embodiment of the invention according to claim 2 by di right coupling to a common secondary winding of the Trans Formator unit or according to an embodiment according to claim 3 in that a separate secondary winding for each primary winding tion is provided, these secondary windings then ge lie together in the secondary circuit and on a shared load output are switched.

According to further embodiments of the invention according to the claims Chen 4 and 5, the voltage converter as a full bridge or be constructed as a half-bridge arrangement.

Preferred embodiments of the invention are in the drawing are shown and are described below.

Show it:

Fig. 1 is a circuit diagram of a primary voltage clocked wall toddlers in a full bridge arrangement with two primary-side sub-systems,

Fig. 2 is a circuit diagram of a primary clocked voltage converter in a half-bridge arrangement with two primary-side subsystems and a single transformer secondary winding and

Fig. 3 is a circuit diagram of a primary clocked voltage converter in a half-bridge arrangement with two primary-side subsystems and two associated transformer secondary windings.

The converter shown in Fig. 1 for transforming an input DC voltage (Ue) into an output DC voltage (Ua) includes a transformer unit, the two windings from primary (TP1, TP2), a secondary winding (TS) and one with the primary windings (TP1, TP2) the secondary winding (TS) may consist of a net coupling iron core (TE). The two primary windings (TP1, TP2) are of identical construction. The secondary winding (TS) is located in a secondary circuit ( 2 ) of the converter, at the output of which a load for feeding with the output voltage (Ua) can be connected, a conventional rectifier stage ( 5 ) being connected upstream.

The primary side ( 1 ) of the converter is made up of two identical subsystems ( 3 , 4 ), which are connected to one another in series between the input terminals via a common line branch ( 11 ). Each subsystem ( 3 , 4 ) is assigned one of the primary windings (TP1, TP2), with a full-bridge switch arrangement made up of four transistor circuit breakers (S11, S12, S13, S14; S21; S22, S23, S24) is provided. The four switches (S11 to S14; S21 to S24) are positioned in such a full-bridge arrangement so that each primary winding connection can be connected to the low or high input potential of the subsystem ( 3 , 4 ) via one of the switches. In operation who the four switches (S11 to S14; S21 to S24) each controlled in pairs cross-synchronously, z. B. at the same time the switches (S11) and (S12), the two pairs of switches, for. B. (S11, S12) or (S13, S14), work in push-pull, so that the respective primary winding, for. B. (TP1), in alternating direction Rich is supplied with current.

To control the transistor circuit breakers (S11 to S24), which are realized in the present case by IGBTs, whereby alternatively MOSFETs or MCTs can also be used, a control unit ( 6 ) serves conventional and therefore not described in detail here. The control unit ( 6 ) provides four control signals on the output side ( 7 , 8 , 9 , 10 ), each of which controls an associated switch of the one subsystem and the corresponding switch of the other subsystem, for. B. the signal ( 7 ), the switches (S11) and (S21). Each switch actuation therefore consists of a simultaneous switching process for two diagonally opposite switches, e.g. B. (S11) and (S12), in a subsystem ( 3 ) and for the corresponding switch pair, z. B. the switches (S21) and (S22), the other Teilsy stems ( 4 ). About the common line branch ( 11 ) with this switch control, the transformer primary windings (TP1, TP2) are each electrically connected in series between the input voltage (Ue), with alternating current direction, while they are magnetic via the common transformer core (TE) are coupled in parallel with the secondary winding (TS). The breakdown of the primary side ( 1 ) into the two subsystems ( 3 , 4 ) has the effect that the voltage load for the circuit breakers (S11 to S24) is approximately halved compared to a conventional full bridge arrangement corresponding to one of the two subsystems ( 3 , 4 ), since each subsystem ( 3 , 4 ) on the connection side lies between an input terminal and the common central line branch ( 11 ) and is therefore only loaded with half the input voltage. In order to keep the middle line branch ( 11 ) even when the power section is switched off, ie when there is no energy transfer to the secondary circuit ( 2 ), at the mean potential Ue / 2, the connection sides of each subsystem ( 3 , 4 ) are additionally parallel via a resistor stood (R1; R2) and a capacitor (C1; C2) connected. Furthermore, each transistor switching path is secured in the usual way by a diode (D1 to D8) connected in parallel.

The voltage converter constructed in this way performs an independent voltage symmetry between the two subsystems in load operation ( 3 , 4 ). Because as soon as an asymmetry occurs in the voltage distribution with the coupled load connected on the output side, the amount of energy absorbed via the primary winding of the subsystem currently having the higher voltage and released into the secondary circuit ( 2 ) increases, while analogously to this, the amount of energy over the other, the subsystem with the currently lower voltage associated primary winding picked up and fed into the secondary circuit ( 2 ) decreases the amount of energy, which means that the voltage in the subsystem with the currently increased voltage drops again, while at the same time the voltage in the subsystem with the currently lower Voltage rises again until the symmetrical voltage distribution is restored. This eliminates the need for this voltage converter lossy voltage symmetry by introducing RC or RCD line branches parallel to the transistor switching paths. Due to the primary system doubling and the resulting series connection of several transistor circuit breakers, the voltage converter is particularly suitable for converting high input voltages of several 100V and more than 1000V depending on the type of transistor used. The possible use of IGBTs as switching transistors with this structure has the further advantage that the line losses increase only linearly and not quadratically with the frequency and that modules with a reverse voltage of 1600V and 300A current carrying capacity are available for larger outputs.

The procedure described, the converter with several pri market-side, jointly controlled subsystems by for the Subsystems are potentially separated, but over time to operate identical clock pulses and those in the subsystems switched voltage on separate, assigned primary windings to give a transformer unit that is on the secondary side coupled, consequently leads to the advantageous property of a voltage stroke limitation in each subsystem voltage manageable by the single circuit breaker, ei ner automatic and practically loss-free voltage symme and a high degree of flexibility with regard to different Input voltages. So it is understood that the tension wall in modified realizations from more than two of the same type term subsystems can be constructed. It also understands that if there is a corresponding need and less input voltage the primary-side subsystems in a simple manner Serial to parallel connection can be regrouped.  

In FIGS. 2 and 3, two DC-DC converters are shown bridge arrangement in half whose primary side (15) is identical been built together with the supplied hearing switch driving part (24 20), so that the individual elements are selected character with the same reference. In particular, this primary part ( 15 ) consists of two subsystems ( 17 , 18 ) framed by dashed lines, which are connected in series between the input voltage (Ue) via a common line branch ( 19 ). Each subsystem ( 17 , 18 ) has its own primary winding (TP3, TP4) assigned to a transformer unit. Together with the respective primary winding (TP3, TP4), each subsystem ( 17 , 18 ) forms a half-bridge push-pull circuit unit, in that the one primary winding connection has a capacitor (C3, C4; C5, C6) and the other primary winding connection has one each Transistor circuit breaker (S31, S32; S41, S42) is connected to the end connections of the associated subsystem ( 17 , 18 ), these end connections in turn being formed on the one hand by the common line branch ( 19 ) and on the other hand with one or the other the other input terminal are connected. To maintain the voltage symmetry when the power section is switched off, each capacitor (C3 to C6) is in turn connected to a resistor (R3 to R6) in parallel, as a result of which the latter form a voltage divider arrangement located between the input terminals. It is understood that to ensure the dynamic voltage symmetry not only the primary windings (TP3, TP4) have an identical structure, but also identical elements for the capacitors (C3 to C6) and the resistors (R3 to R6) are selected, what applies analogously to the example of FIG. 1. The switch is controlled by four output signals ( 21 to 24 ) of a control unit ( 20 ) such that the two switches (S31, S32) and (S41, S42) of a subsystem ( 17 , 18 ) each in push-pull and the corresponding switch different subsystems, ie the switches (S31) and (S41) or the switches (S32) and (S42), are each controlled synchronously.

With identical construction of the primary part ( 15 ), as described above, the transducers of FIGS. 2 and 3 differ in the construction of the transformer unit and of the secondary circuit as follows.

Analogous to the converter of FIG. 1, the transformer unit of the converter of FIG. 2 contains a single secondary winding (TS1) and an iron core (TE1) that couples this secondary winding (TS1) with the two primary windings (TP3, TP4) magnetically. The secondary circuit ( 16 ) containing the secondary winding ( 16 ) has the structure typical of a push-pull converter in a half-bridge circuit with center tapping of the secondary winding (TS1) and the two secondary diodes (D9, D10) connected to the end-side secondary winding connections, their connection point a memory inductor (L) is switched downstream, a smoothing capacitor (C7) being looped in parallel to the output.

As can be seen from the described structure, the operation of this half-bridge voltage converter results in the same advantages, achieved by splitting the primary side ( 15 ) into two mutually adjacent subsystems ( 17 , 18 ), of halving the load on the circuit breakers (S31 to S42) and an automatic, lossless, dynamic voltage balancing for the subsystems ( 17 , 18 ) due to the electrically serial and via the transformer unit magically parallel coupling of the transformer primary windings (TP3, TP4), for which reference is made to the analogous explanations for the converter of FIG. 1 can. Here, too, the automatic voltage symmetry results from the fact that deviations from this symmetry are counteracted by the corresponding increased or decreased energy output via the primary windings (TP3, TP4).

In the modification of the converter of FIG. 2 shown in FIG. 3, the transformer unit contains two separate transformers, each primary winding (TP3, TP4) being assigned its own secondary winding (TS2, TE3) via its own iron core (TE2, TE3). The two secondary windings (TS2, TS3) are connected in parallel in an otherwise corresponding to that ( 16 ) of the converter of Fig. 2 corresponding secondary circuit ( 25 ), wherein he required for each secondary winding (TS2, TS3) Chen two diodes (D11 to D14) and this is followed by the common memory inductor (L) and parallel to the output the smoothing capacitor (C7). Through the electrically parallel coupling of the two separate secondary windings (TS2, TS3) to the output of the secondary circuit ( 25 ) for connecting the load, the common coupling of the two primary windings (TP3, TP4) to the common load output is realized. For this converter, too, the advantages specific to the invention mentioned in relation to the examples of FIGS. 1 and 2 result in a voltage load halving of the transistor circuit breakers and an automatic voltage symmetry by the circuitry structure of this converter due to the coupling of the primary windings (TP3, TP4 ) to the common load ensures that with voltage asymmetries in the two subsystems ( 17 , 18 ) and thus on the two primary windings (TP3, TP4) an increased energy transfer via the primary winding with the higher voltage compared to that over the primary winding with the lower Voltage is applied to the common load, which then causes the increased voltage to drop again, while the reduced voltage rises again until the voltage symmetry is restored.

It goes without saying that, in addition to the examples shown in FIGS. 2 and 3, further variants are also possible for the converter type according to the invention in a half-bridge arrangement, for example a primary-side structure with more than two identical subsystems. All converters according to the invention have in common that, by dividing the primary side into several subsystems, the provision of a voltage-reducing series connection of transistor circuit breakers, for. B. in the form of MOSFETs or IGBTs, with an automatic voltage balancing between the subsystems is achieved by assigning separate transformer primary windings, which are coupled via the secondary circuit, to which a common load is connected.

Claims (5)

1. Primary clocked voltage converter, in particular for high DC input voltages, with

• - a transformer unit (TP1, TP2; TE; TS) with at least one secondary winding (TS),
• - One of the output voltage (Ua) providing secondary circuit ( 2 ), in which the at least one secondary winding (TS) is looped, and
• - A primary circuit ( 1 ) which can be acted upon by the input DC voltage (Ue) and which contains subsystems ( 3 , 4 ) connected in series, each with at least one transistor circuit breaker (S11 to S24) for clocked current conduction in the primary circuit,
  characterized in that
• - The transformer unit has a number of primary primary systems ( 3 , 4 ) corresponding number of separate primary windings (TP1, TP2), wherein
• - Each subsystem ( 3 , 4 ) a primary winding (TP1, TP2) is assigned to and the primary windings (TP1, TP2) are arranged electrically in series and coupled to the common secondary circuit ( 2 ) magnetically parallel.

2. Voltage converter according to claim 1, further characterized thereby records that a single secondary winding (TS) is provided to which all primary windings (TP1, TP2) are coupled. 3. Voltage converter according to claim 1, further characterized in that a separate secondary winding (TS2, TS3) is provided for each primary winding (TP3, TP4), the secondary windings in the secondary circuit ( 25 ) being connected to a common load output. 4. Voltage converter according to one of claims 1 to 3, wei ter characterized in that it forms a full bridge arrangement, each primary-side subsystem ( 3 , 4 ) four Tran sistor line switches (S11, S12, S13, S14; S21, S22, S23 , S24), which can be controlled in pairs in a push-pull manner. 5. Voltage converter according to one of claims 1 to 3, wei ter characterized in that it forms a half-bridge arrangement, each primary-side subsystem ( 17 , 18 ) having two push-pull controllable transistor circuit breakers (S31, S32; S41, S42).