DE2819676A1 - DC voltage converter for power supply - has at least two half-bridge converters using transformer primary winding sections separated by transistors - Google Patents

Abstract

A series of capacitors bridges the input terminals. Transformer primary windings have switching transistors connected between them. Each winding and transistor unit is connected across one of the capacitors. Diodes and an inductor are connected to the transformer's secondary winding. At least two half-bridge converters are connected in series, operating on the transformer's (9) core. Primary windings (5-8) following each other in pairs are wound in the same sense, and non-adjacent transistors (T1, T3; T2, T4) are operated in phase.

Description

"Switching power supply" for high input voltages "

The invention relates to a circuit arrangement for supplying loads with half-bridge converter as DC voltage converter, with the between the input terminals Capacitors are connected in series, each of which is a series connection Primary winding of a transformer with a switching transistor are in parallel and in which a secondary winding of the transformer is wired with diodes and a choke is.

The invention also relates to a circuit arrangement for supplying loads with a double flow converter as a DC voltage converter each in series with a primary winding of a transformer a switching transistor and in the secondary windings of the transformers with diodes and a choke are connected.

The circuit arrangements according to the invention for supplying consumers or switching power supply units with DC voltage converters can be used for potential-free power supply electronic loads from direct or alternating current networks are used.

A switching power supply or clocked power supply with a so-called "half-bridge converter" is for example from the BBC publication D NG 70181 D, BBC power supply units Cetact, Series 200, single and multiple output, technical data, project planning information, page 2, Fig. 1, known. The clocked power supply is operated with a fixed clock frequency of 20 kllz, the output voltage is controlled via pulse width control on the mains side arranged power stage stabilized with switching transistors.

A clocked power supply unit with a so-called "double flow converter" is for example from the ValvoZeminarSchalt-Netzteile, February 1977, lecture series of the Technical Academy Esslingen, chapter flow converter, page 7, Fig. 7, known. The double flow converter is well suited for switching power supplies with high performance with an exit.

These known switching power supplies have the disadvantage that when Use of the currently commercially available switching transistors only about 350 ... 400 V DC input voltage let it be controlled safely. This means that it is not possible to use a switching power supply unit in direct operation to be operated on a three-phase network 3 x 380 V, as this takes a network voltage tolerance into account of + 20% a DC link voltage of 650 V occurs.

The invention is based on the object of having a switching power supply To design DC voltage converters in such a way that it is suitable for high input voltages, is particularly suitable for operation on a three-phase network.

This task is performed with a switching power supply unit with a half-bridge converter according to the invention achieved in that at least two half-bridge converters in series connected to a common transformer core of the transformer work, with each pair of successive primary windings of the transformer have the same winding direction and each non-adjacent switching transistors in Are controllable in the same mode.

The solution to the problem posed is a switching power supply unit with double flow converter according to the invention in that the individual flow converter are connected in series, with capacitors in series between input terminals are provided, each of which is the series connection from the primary winding one Transformer is connected in parallel with a switching transistor.

The demagnetization windings of the transformers feed in the process while on the capacitor lying parallel to the corresponding primary winding.

Alternatively, the demagnetizing windings of the transformers can be used also feed on the capacitor lying parallel to the neighboring primary winding.

The advantages that can be achieved with the invention are in particular in that the voltage stress of the switching transistors compared to conventional Switching power supplies is reduced. This means that higher input voltages can be used than before usually be created. The switching power supplies according to the invention have a high Efficiency 1 and low heat loss. Switching power supplies with double flow converter are also insensitive to scatter of the components, i.e. in particular against scattering of the switching transistors.

Embodiments of the invention are described below with reference to the drawings shown.

1 shows a switching power supply according to the invention with a half-pulse converter. FIG. 2 shows a switching power supply according to the invention with a double flow converter, FIG. 3 a variant of FIG. 2, FIG. 4a, the time courses of interest from actuation to 4f signals, voltages and currents.

In Fig. 1 is an inventive switching power supply with half-bridge converter shown. The DC input voltage is between input terminals 1 and 2 of the circuit Ue on, where terminal 1 is connected to the positive pole and terminal 2 to the negative pole is. The stabilized output voltage UA can be tapped at output terminals 3 and 4 terminal 3 positive, terminal 4 negative polarity.

Between the input terminals 1 and 2 there are four capacitors C1 C2, C3 and C4 arranged in series. The connection points between the condensers C1, C2 C3> C4 with each other and the two end points of the capacitor series connection four primary windings 5,6,7 and 8 of a transformer 9 are fed, the Primary windings 5,6,7,8 are each similar and on the same transformer core work, but sometimes have different winding directions. The primary windings 5 and 7 as well as 6 and 8 each have the same winding direction.

In detail is terminal 1 with capacitor C1 and a connection terminal connected to the primary winding 5, the other terminal of which via the collector-emitter path a switching resp.

Power transistor T1 at the connection of the capacitors cl and C2 and a terminal of the primary winding 6 is located.

The other terminal of the primary winding 6 is above the collector-emitter path a switching transistor T2 connecting the capacitors C2 and C3 and one Terminal of the primary winding 7 is supplied.

The other terminal of the primary winding-7 is above the collector-emitter path a switching transistor T3 at the connection of the capacitors C3 and C4 as well as at one terminal of the primary winding 8. The other terminal of this primary winding 8 is across the collector-emitter path of a switching transistor T4 of the input terminal 2 and the capacitor C4.

The transformer 9 has a secondary winding 10 with a center tap on. The two outer terminals of the secondary winding 10 are via diodes D1 and D2 interconnected and fed to the output terminal 3 via a choke 11. the Diodes D1, D2 are connected on the cathode side. The center tap of the secondary winding 10 is fed to the output terminal 4. Between output terminals 3 and 4 is a capacitor C5 is arranged.

The collector-emitter voltages at the switching transistors T1, T2, T3 and T4 are labeled UCE1, UCE2 ', UCE3 and UCE4, respectively. The one in front of the throttle The voltage dropping 11 is with UA 'and the voltage flowing on the output side via terminal 3 Current is marked with IA. The voltages between the collectors of the transistors T1, T2, T3, T4 and terminal 2, which is used as a reference terminal, are labeled U1, U2, U3, U4 denotes, where UCE4 corresponds to the voltage U4.

In Fig. 2 is an inventive switching power supply with double flow converter shown. The DC input voltage is between input terminals i2 and 13 of the circuit UE on, with terminal 12 connected to the positive pole, terminal 13 to the negative pole is. The stabilized output voltage UA can be tapped at output terminals 14 and 15 terminal 14 positive, terminal 15 negative polarity. Between the input terminals 12 and 13 two capacitors C6 and C7 are arranged in series. In particular, terminal 12 is connected to capacitor C6, and terminal is one Primary winding 16 and to the terminal of a demagnetizing winding 17 a transformer 18 connected. The other terminal of the primary winding 16 is common across the gate-emitter path of a switching transistor T5 Connection of capacitors C6 and C7 and the connection terminal of a primary winding 19 and the connection terminal of a demagnetizing winding 20 of a transformer 21 supplied. The two Demagnetizing windings 17 and 20 are connected to one another via a diode D3, the diode D3 on the cathode side is on winding 17.

The other terminal of the primary winding 19 is on the collector-emitter path a switching transistor T6 with the capacitor C7, the input terminal 13 and above a diode D4 is connected to the degaussing winding 20, the diode D4 on the cathode side is connected to winding 20.

The transformers 18 and 21 quiet SeL-undärwicklungs 22 and

23 on. The output terminal 14 is above a choke 24 and one Diode D5 on a first terminal of the secondary winding 22 and over one Diode D6 on a first connection terminal of the secondary winding 23, the diodes D5 and D6 are connected on the cathode side. The other terminals of the Windings 22 and 23 are fed directly to the output terminal 15.

A diode D7 bridges the outputs of the two in parallel lying windings 22 and 23 and is on the cathode side of the diodes D5 and D6. A capacitor C8 is arranged between the output terminals 14 and 15. the Transformers 18 and 21 each have the same winding direction. The ones in the drawings The points entered show the winding direction.

The collector-emitter voltages at the switching transistors T5 and T6 are labeled UCE5 and UCE6, respectively. The falling in front of the throttle 24 Voltage is with UAt and the current flowing on the output side via terminal 14 is with 1A marked.

The voltages between the collectors of transistors IT6 and the Terminal 13 serving as a reference terminal is denoted by U5, U6, UcE6 being the Voltage U6 corresponds.

In Fig. 3 is a variant of the switching power supply according to the invention shown with double flow converter according to FIG. 2, namely the demagnetizing windings 17 and 20 of the transformers 18 and -21 operated in a different manner than in FIG interconnected.

The one terminal of the winding 17 is no longer on the terminal 12, but at the junction of capacitors C1 and C2. The other connector the winding 17 is fed to the terminal 13 via the diode D3, the diode D3 on the cathode side connected to terminal 17.

The one terminal of the demagnetizing winding 20 is not more at the connection point of capacitors C6 and C7, but at the input terminal 12. The further connection terminal of the winding 20 is the connection point via the diode D4 of the capacitors C6 and C7, the diode D4 on the cathode side at Terminal 20 is located. The further wiring of the arrangement according to FIG. 3 is analogous to that described under Fig. 2.

The following describes the mode of operation of the switching power supplies according to the invention explained.

The switching power supply units should generally be galvanically connected to the line side Output a separate, stabilized DC output voltage. That on the input side applied three-phase voltage system 380 V is by means of a not shown Rectifier rectified, screened and this DC voltage UE is the input terminals 1 and 2 or 12 and 13 supplied. A converting DC voltage is applied to the input terminals 1 and 2 or 12 and 13 supplied directly.

An approximately even voltage distribution of the input voltage UE on the individual primary windings 5,6,7 and 8 of the transformer 9 is through the capacitive voltage divider C1, C2, C3 'and C4 in the half-bridge converter power supply in the case of the double flow converter power supply unit, the capacitive voltage division takes place the input voltage UE to the primary winding / 16 and 19 of the transformers 18 and 21 through capacitors c6 and C7.

The DC voltages obtained in this way are quickly; ski transistors T1, T2, T3, T4, T5 and T6 are chopped up.

The switching transistors are operated with a fixed clock frequency from operated for example 20 kHz.

Of course, other clock frequencies can also be used, however, the clock frequency should be above the upper hearing limit of the human hearing to achieve freedom from interference.

The power transistors T1 ... T6 are usually potential-free controlled by a control logic via not shown here about carriers at their bases and serve as controlled switches. With the help of the fast switching or power transistors T1 ... T4 or T5, T6 a 20 kHz alternating voltage is generated, which the power transformers, i.e. the transformers 9 and 18 and 21, respectively.

The transformers 9, 18, 21 translate this alternating voltage the desired potential level and at the same time take over the potential separation. The ones obtained on the secondary windings 10 and 22, 25 of the transformers 9 and 18, 21, respectively Voltages are rectified and respectively by the diodes D1, D2 and D5, D6 sieved by means of the choke-capacitor arrangements 11, C5 or 24, C8.

In the case of the switching power supply with half-bridge converter according to FIG. 1, D1 act and D2 as freewheeling diodes, in the case of the switching power supply unit with double flow converter according to FIG 2, 3, D7 acts as a freewheeling diode.

The desired output voltage UA is set by adjusting the width of the control signal for the switching transistors T1 ... T6 are set and via a Pulse width regulation stabilized.

The duty cycle of the 20 kHz control voltage for the power transistors T1 ... T6 is depending on the desired output voltage UA at a fixed clock frequency changed, namely the higher the pulse width, the higher the output voltage UA.

There is another possibility of changing the output voltage UA in influencing the clock frequency.

If more than one output voltage is required, the number will be the secondary windings of the power transformer, i.e. the transformers 9 resp. 18 and 21 increased accordingly, the number of secondary windings of the power transformer is always the number of output voltages.

For the functioning of the power supply unit with half-bridge converter according to Fig. 1 the time courses of control signals of interest are shown below, Considered voltages and currents according to FIG.

In Fig. 4a the drive signals 5T1 and 5T3 are for the transistors T1 and T3 and, in FIG. 4b, the control signals 5T2 and 5T4 for the transistors T2 and T4 shown.

The transistors T1 and T3 are in the time periods t1 Z t # t2, t11 c tt2 ', t1tt - tct2tt ... in the conductive state, i.e. their collector-emitter paths are activated (in Fig. 4: H o on state, L 2 off state of the transistor).

The transistors T2 and T4 conduct in the time periods t3 <t3'e t # t4 '... and are locked in the remaining periods.

In Fig. 4c are the time curves of the voltages between the Collectors of transistors T1, T2, T3, T4 and terminal 2 of the half-bridge converter power supply shown in FIG.

The transistors T1 and T3 as well as the transistors T2 and T4 are each together, the transistor pairs T1 / T3 and T2 / T4 each driven in push-pull, all transistors being blocked after each conducting phase.

As can be seen from Fig. 4c, the voltage U1 (dash-dotted line shown) in the period t1 r t't2 their minimum value 3/4 UE (transistor T1 is located in the conductive state), the voltage U2 (shown dotted) reaches its Maximum value UE (transistor T2 is in the blocking state), voltage U3 (dashed shown) has its minimum value 1/4 UE (transistor T3 conducts) and the voltage U4 (solid line) reaches its maximum value 1/2 UE (transistor T4 blocks). The voltage A UA 'falling in front of the choke 11 has its in the period t1 # t't2 Peak value UA '(Fig. 4e).

The current IA flowing through the output terminal 3 rises from its Minimum value IAU at time t1 to its maximum value AIA at time t2 (Fig. 4f).

In the following time period t2 # t'tD all transistors are; locked. The voltage U1 now has the value UE, the voltage U2 has dropped to the value 3/4 UE, the voltage U3 has the value 1/2 UE and the voltage U4 the value 1/4 UE (Fig. 4c).

The voltage UA 'has dropped to the value 0 (FIG. 4e). It educates A transformer demagnetizing current 1A is now used as freewheeling diodes acting diodes D1 and D2, which drops from the peak value ÎA to the minimum value IAU (Fig. 4f).

In the period t3 = t't4, the transistors T2 and T4, the transistors, conduct T1 and T3 are in the locked state. The voltage U1 has its maximum value 5/4 UE reached, the voltage U2 has dropped to its minimum value 1/2 UE, the voltage U3 has its maximum value 3/4 UE and the voltage U4 has its minimum value 0 (Figure 4c). The voltage UA 'has reached its peak value ÛA' (Fig. 4e) and the current 1A increases from the minimum value IAU to the maximum value AIA (FIG. 4f).

In the following period t4 'tat1' all transistors are again locked. The voltage U1 has the value UE, the voltage U2 has the value 3/4 UE increased, the voltage U3 has the value 1/2 UE and the voltage U4 the value 1/4 UE on (Fig. 4c).

The voltage UA 'has the value 0 (FIG. 4e) and the transformer demagnetizing current IA falls from the value IA to the value IAU (FIG. 4f). The current IA flows in turn via the diodes D1, D2 acting as free-wheeling diodes.

The individual collector-emitter voltages UCE1, UCE2, UGE3, UCE4 oscillate between the values UCE = 0 and UcE = 1/2 UE, i.e. the transistors must can only be designed for a reverse voltage of 1/2 UE.

In the following periods the described ones are repeated Current and voltage curves. This results in an average current flowing on the output side from IAM.

The voltages and currents for / of interest are given below the power supply unit with double flow converter according to Fig. 2.3 considered.

In Fig. 4a the control signal ST5 for the transistor T5 and in Fig. 4b shows the control signal ST6 for the transistor T6. The transistor T5 is then in the period tl 't't2 in the conductive state, the transistor T6 is switched through in the period t3 t t4. In the remaining periods there are the transistors T5, T6 each in the blocking state.

In Fig. 4d are the time curves of the voltages between the Collectors of transistors T5, T6 and terminal 13 of the double forward converter power supply shown in Fig. 2,3.

In the period t1 t tt2, the voltage U5 (solid line) their minimum value 0 (transistor T5 is in the conductive state) and the Voltage U6 (shown in dashed lines) has the value UE. The falling in front of the throttle 24 Voltage UA 'has its peak value UA' (FIG. 4e). The one across the diode D5 and the output terminal 14 flowing current 1A increases from its minimum value IAU to Time t1 to its maximum value 1A at time t2 (FIG. 4f).

In the subsequent period t2 f tct3, both transistors T5, T6 are locked. The voltages U5 and U6 both have the value UE (FIG. 4d). The voltage UA 'has dropped to the value 0 (FIG. 4e) and the current 1A' in this pre-run phase flows through the conductive diode D7, decreases from the value iA to the value 1AU (Fig. 4c).

The during the previous conduction phase of the transistor T5 from Transformer 18 absorbed magnetization energy is over the demagnetization winding 17 to the one between the input terminals 12, 13 during this blocking phase DC power source returned.

In the period t3 = t-t4, transistor T5 blocks, while transistor T6 is in the control state. The voltages U5 and U6 UE have the value 2 (Fig. 4d). The voltage UA 'has again reached its peak value UA t (FIG. 4e) and the now over Diode D6 flowing current 1 increases from its minimum value IAU AA to its maximum value 1A (Fig. 4f).

In the following period of time t4 X tut 'both are again Tran-UE sistors T5, T6 blocked. The voltage U5 retains the value E while the voltage U6 has reached its maximum value 3/2 UE (Fig. 4d). The voltage UA 'has again the value 0 (FIG. 4e) and the value flowing through the diode D7 in this freewheeling phase Current 1A drops from the value IA to the value IAU (FIG. 4f).

The during the previous conduction phase of the transistor T6 from Transformer 21 absorbed magnetization energy is over the demagnetization winding 20 during this blocking phase to the one between the input terminals 12, 13 DC power source returned.

In the following periods the described ones are repeated Current and voltage curves. This results in an average current flowing on the output side I AM.

The collector-emitter voltages UCES, UcE6 oscillate between the values UCE = 0 and UCE = UE, i.e. the transistors must for a reverse voltage be interpreted by UE.

The different wiring shown in FIGS. 2 and 3 of the demagnetizing windings 17 and 20 is expressed in that according to FIG Reverse magnetization winding 17 over the Diode D3 on the capacitor C6 and the back magnetization winding 20 via the diode D4 to the capacitor C7 feeds, while, as shown in FIG. 3, the reverse magnetization winding 17 via the diode D3 to the capacitor C7 and the reverse magnetization 'winding 20 via the diode D4 feeds to the capacitor C6.

The switching power supplies according to the invention are particularly useful in power supply systems higher power can be used with success, in particular from about 1 KW output power the solution with a double flow converter is more advantageous.

If the switching power supply is connected to input voltages even higher than approx. 650 V is to be connected, the principle according to the invention of the series connection of primary windings of half-bridge converters or the series connection of individual ones : Continue flow converters as desired.

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Claims (4)

Claims 1. Circuit arrangement for supplying loads with Half-bridge converter as DC voltage converter, between the input terminals Capacitors are connected in series, each of which is a series connection Primary winding of a transformer with a switching transistor are in parallel and in which a secondary winding of the transformer is wired with diodes and a choke is that at least two half-bridge converters are connected in series on a common transformer core of the transformer (9) work, with successive primary windings (5, 6, 7, 8) of the transformer (9) have the same winding direction and are not adjacent Switching transistors (T1, T3; T2, T4) can be controlled in common mode. 2. Circuit arrangement for consumer supply with double flow converter as a DC voltage converter, each in series with a primary winding one Transformer is a switching transistor and the secondary windings of the transformers are connected with diodes and a choke, characterized in that the individual Flow converters are connected in series, with clamps in series between inlets (12,13) lying capacitors (C6, C7) are provided, each of which is connected in series from the primary winding (16,19) of a transformer (18,21) with a switching transistor (T5, T6) is connected in parallel. 3. Switching power supply according to claim 2, characterized in that the Demagnetization windings (17, 20) of the transformers (18, 21) on the corresponding one Feed the primary winding (16, 19) parallel capacitors (C6, C7). 4. Switching power supply according to claim 2, characterized in that the Demagnetization windings (17, 20) of the transformers (18, 21) on those of the neighboring ones Feed the primary winding (19, 16) parallel capacitor (C7, C6).