JPH10503360A - Power supply with improved amplitude limiting circuit - Google Patents

Abstract

(57) [Summary] The power supply device serves to convert an electric DC voltage acting as an input voltage into an output voltage, and has positive and negative input terminals (1, 3) arranged to receive the input voltage. I have it. The power supply also comprises a first series connection (7) of at least a first coil (9) and a controllable switching element (11) interconnecting the two input terminals (1,3) and a first capacitor (31). ) And an amplitude limiting circuit (29) comprising at least a second coil (35), a second series connection (33) of a first rectifying element (37) and a second rectifying element (39); A connection is connected in parallel with the first series connection such that the cathodes of the first and second rectifying elements are directed towards the positive input terminal (1); one electrode of the first capacitor is connected to the second rectifying element. The other electrode is connected to the anode and the junction of the first coil and the switching element. Said second series connection also comprises an auxiliary voltage source arranged to supply a series voltage approximately equal to half the input voltage, the positive pole of which is directed to the positive input terminal (1). The presence of this auxiliary voltage source (55) is such that when the switching element (11) is switched off, voltage jumps that cause undesirably high energy waste and disturbances (electromagnetic interference, EMI) at the switching element cross the switching element. Prevent it from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION                  Power supply with improved amplitude limiting circuit   The present invention relates to a power supply for converting an electric DC voltage acting as an input voltage to an output voltage. Source device; positive and negative input terminals arranged to receive an input voltage; At least a first coil interconnecting both input terminals and a controllable switch A first series connection of the switching elements, a first capacitor, at least a second coil, and a first rectifier. And a second series connection of the element and a second rectifying element. The two series connection is such that the cathodes of the first and second rectifying elements are oriented towards the positive input terminal. Connected in parallel with the first series connection; one electrode of the first capacitor is connected to the second Connected to the anode of the flow element, while the other electrode is connected to the first coil and the switching element. The present invention relates to a power supply device connected to a junction.   Such devices are described, for example, in Elektronik Industrie 1 (1986), 44, 46, 48, particularly notably from FIG. This amplitude limiting circuit is switched To prevent very fast buildup of voltage across the switching element immediately after turning off work. After the switching element is opened, the magnetic energy stored in the first coil is first It is used initially to charge a first capacitor via a second rectifying element. Sui To the extent that the voltage across the switching element reaches a value that is no longer negligible. When the first capacitor is charged at To the extent that no or little power is consumed by the switching elements Reduced. The charge stored in the first capacitor then returns to the input voltage source. Applied to the load connected to the force terminal. After closing the switching element, the first The polarity of the charge of the sensor is transmitted through the switching element, the first rectifying element and the second coil. And inverted. In the most favorable case, the voltage across the switching element Must be equal to zero after the polarity of the sensor voltage is inverted. Should start from exactly zero. However, when switching off Voltage jumps can occur through the switching elements, and these voltage jumps It causes power waste and disturbance (EMI: electromagnetic interference).   It is therefore an object of the present invention to provide a voltage jump when a switching element is switched off. To provide a power supply of the kind mentioned at the outset, so that no longer occurs Things. In order to achieve this object, the power supply according to the present invention includes the second series Auxiliary in which the connection is also arranged to supply a DC voltage equal to approximately half the input voltage A voltage source, the positive electrode of which is directed to a positive input terminal Things. As a result of this action, voltage jumps no longer occur via the switching element. It is shown in principle and experimentally that it does not occur. The auxiliary voltage source is preferably a second It is located at one of two terminals in series.   Various possibilities exist for the implementation of the auxiliary voltage source. The first embodiment is a A second capacitor having an auxiliary voltage source connected between the cathode of the second rectifying element and the positive input terminal Wherein the electrode of the second capacitor connected to the cathode of the second rectifying element also has a third Connected to the anode of the rectifying element, the cathode of the third rectifying element being approximately halfway It is characterized by being connected to a tap of a first coil located. Second In an embodiment, the auxiliary voltage source is connected between the negative input terminal and the second coil and the first Voltage pulse applied to the input terminal in the third coil A third coil magnetically connected to the first coil to induce a pressure pulse; The number of turns of the third coil is approximately half of the number of turns of the first coil. Is what you do. The construction of these two embodiments is simple and uses few additional components. It is not used and therefore inexpensive.   These and other aspects of the invention are described in detail below by way of example with reference to the accompanying drawings. Explained.   Referenced drawings:   1A and 1B are a schematic diagram and a related circuit diagram of a first embodiment of a power supply device according to the present invention. Show each route map,   FIG. 2 shows the variation of some voltages of the circuit shown in FIG. 1 as a function of time;   FIGS. 3A, 3B and 3C show some examples illustrating the operation of the power supply according to the invention. Shows a diagram,   4A and 4B are a schematic diagram and a related circuit diagram of a power supply device according to a second embodiment of the present invention. Each route map is shown.   The circuit diagram of FIG. 1A whose circuit diagram is shown in FIG. 1B has a positive input terminal 1 and a negative input terminal. It has input terminals 3 to which, for example, batteries or power line rectifiers (not shown) An electrical DC voltage is applied. Input capacitor placed between both input terminals 1 and 3 5 acts to smooth the ripple voltage, if any. Further In addition, the two input terminals 1, 3 are in this case a first coil 9 and a controllable switching element 1 1 via a first series connection 7. The first coil 9 is a secondary coil A primary coil of the transformer 13 also comprising an il 15. Controllable in this embodiment Switching element 11 is formed by an NPN-type bipolar transistor . Sometimes other known switching elements, such as PNP transistors or MOS FETs are also used. The control circuit 17 electrically switches the switching elements 11 alternately. Switch to the element's control electrode to set it to conductive and non-conductive states Pulses are supplied periodically. The secondary coil 15 of the transformer 13 includes a diode 19 and And the output capacitor 21 in series. The output capacitor 21 is a load 27 A positive output terminal 23 and a negative output terminal 25 (shown by dashed lines) are connected. Connected to   The power supply also comprises an amplitude limiting circuit 29, which comprises a first capacitor 31 and a The second series connection is, inter alia, a second coil 35, a first rectifier. An element 37 and a second rectifying element 39 are provided. The second series connection 33 includes the first and The second rectifying elements 37, 39 are arranged such that their cathodes are oriented towards the positive input terminal 1. One series connection 7 is connected in parallel. One electrode of the first capacitor 31 is connected to the second It is connected to the anode of the rectifying element 39. In this embodiment, the anode of the second rectifying element 39 is Is also connected to the cathode of the first rectifying element 37, this junction being indicated by reference numeral 41. I have. However, instead of this, the positions of the second coil 35 and the first rectifying element 37 are exchanged. It is also possible to exchange. The other electrode of the first capacitor 31 is connected to the first coil 9 It is connected to the junction 43 of the switching element 11. The power supply that has been described The device is the same as a known power supply, for example the power supply described in the introduction. However Thus, the circuit shown in FIG. 1 is well known in that the second series connection 33 also includes an auxiliary voltage source. Unlike the circuit, the auxiliary voltage source is connected between the cathode of the second rectifying element 39 and the positive input terminal. The second rectifying element is formed by the connected second capacitor 45 and connected to the cathode of the second rectifying element. The electrode of the second capacitor is also connected to the first coil 9 via the third rectifying element 47. Connected to the power supply 49. The third rectifying element 47 has an anode connected to the second capacitor 45. Oriented to be connected.   In the circuit diagram of FIG. 1B, the transformer 13 includes the primary coil 9 and the distributed inductance 51. Shown as a combination with Connected to both input terminals 1 and 3 of input capacitor 5 The combination with the voltage source to be used is shown as a power supply battery 53, and the second capacitor 45, the third The auxiliary voltage source formed by the rectifying element 47 and the tap 49 is an auxiliary battery 55. Shown.   The illustrated power supply mainly operates as follows. Switching element 11 Is electrically conducted, the current switches from the positive input terminal 1 to the first coil 9. It starts flowing through element 11 to the negative input terminal 3. As a result, the magnetic energy is 13 is stored. When the switching element 11 is opened, this energy is A current is generated in the output capacitor 2 via a diode 19. 1 is charged and power is supplied to the load 27. The current through the primary coil is the switching element 1 This coil and the switching element, since they only decrease slowly after 1 The voltage at the junction 43 of this will increase quite rapidly if no further action is taken will do. The current in the switching element 11 is Since it decreases only slowly after being turned off, the switching element Consumes a lot of energy, so it is severely damaged. In addition, Sui The jump in voltage that occurs across the switching element 11 causes electromagnetic interference. this The drawback is that the current of the first coil 9 passes through the first capacitor 31 and the second rectifying element 39. Avoided by being discharged. The energy is then stored in the capacitor 31.   The operation of this circuit will be described in more detail below with reference to FIG. Where No. used: V_i: Input voltage (voltage across power supply battery 53) V_o: Output voltage (voltage across output capacitor 21) n: conversion ratio of transformer 13 V_c: Voltage across the first capacitor 31 V_x: Voltage across auxiliary battery 55 V₄₁And V₄₃: Voltage at junctions 41 and 43 ΔV: voltage across distributed inductance 51   If necessary, the polarity of these voltages is indicated by the symbols + and-near the relevant components in FIG. 1B. Have been. FIG. 2 shows the voltage V as a function of time t.₄₃, V_cAnd V₄₁Each change Three curves 57, 59 and 61, which indicate the transformation, are shown one after the other.   Energy stored in first capacitor 31 when switching element 11 is open Is the output voltage V_oAnd the energy of the distributed inductance 51 of the transformer 13 Depends on. If this maximum amount of energy is stored in the first capacitor 31 No, the second rectifying element 39 will not reduce this energy. Sui Immediately after the opening of the switching element 11 (instantaneous t_o), The voltage at junction 43 (see curve 57 in FIG. 2). ) Is the input voltage V_iAnd the output voltage nV converted to the primary side of the transformer 13_oValue and distribution It is equal to the sum of the voltage ΔV across the conductance 51. After the degaussing phase (instantaneous t₁rear This voltage is V_i+ NV_oAnd the energy existing in the first coil 9 is reduced to the load 2 7 (the instant t_TwoAfter) is V₄₃Is V_iTo decrease. Dead time After (dead time, instant t_ThreeAfter) the switching element 11 closes again and V₄₃Is to zero Decrease. As the voltage at the junction 41 increases, the second rectifying element 39 becomes conductive. I'm starting to do it at most V_i-V_x(See curve 61 in FIG. 2). 1st conden Voltage V across_cInstantaneous t_oAnd V₄₃-V₄₁= NV_o+ ΔV + V_xBecomes (See curve 59 in FIG. 2). The voltage across the first capacitor 31 is then Maintain a constant value until the battery can discharge. As a result, the voltage jump at the junction 43 is at the point 41. Will cause voltage jumps. As soon as the voltage at point 41 becomes negative, the first rectification Element 37 will be conductive. Depending on the instantaneous phase of the circuit, at least the first An oscillation circuit including the capacitor 31 and the second coil 35 is formed. During demagnetization (t₁ ), Energy is applied to the output and between the degaussing phase and the dead time (t_Three Energy) returns to the input. Switching element 11 is instantaneous t_ThreeAnd closed T_TwoIn the case of discontinuous operation in which dead time occurs after The voltage across the element is V_iIs equal to This is the situation shown in Figure 2. It is. Operate continuously or after degaussing then t₁And t_TwoShort-time switching element between It is also possible to close 11. In that case V₄₃Just before closing To V_i+ NV_oIs equal to V in any case₄₃Means the switching element 11 is closed At least V just before_iIs equal to V₄₁At best V_i-V_xEqual to Therefore, the voltage across the first capacitor 31 is at least     V_c= V₄₃-V₄₁= V_i− (V_i-V_x) = V_x                 (1) be equivalent to. After the switching element 11 is closed, it crosses the first capacitor 31 The polarity of the voltage will be reversed. This means that the voltage across the first capacitor 31 -V when the switching element 11 is open_xMeans equal to Then switch Jumps across the switching element 11     V₄₃= V₄₁+ V_c= V_i-V_x+ V_c= V_i-2V_x              (2) be equivalent to. From equation (2), the voltage across switching element 11 is V_xTo 1 / 2V_iWhen It can be made equal to zero by choosing. First after switching element 11 is opened Current I of coil 9_pPart flows first through the first capacitor 31, so that Voltage V across switching element 11_TWill only grow relatively slowly On the other hand, the current through the switching element will decrease relatively quickly. See FIG. The voltage across the switching element 11 starts at zero, as explained below. Is advantageous.   FIG. 3 shows the current I for three cases immediately after the opening of the switching element 11._TAnd voltage V_T Where t = 0 corresponds to the instant of opening. FIG. 3A shows the amplitude limit times. The case where the road 29 does not exist is shown. In this case V_TIs immediately after switching element 11 is opened Increases very rapidly while the current I_TJust then begins to decrease. Both current and voltage As long as the power is greater than zero, energy is wasted in the switching element 11. Wasted The amount of energy applied is proportional to the shaded area in the figure. FIG. 3B shows a known circuit. When the amplitude limiting circuit 29 is present but the auxiliary voltage source 55 is not provided, Voltage source is substantially 1 / 2V_iFigure 4 illustrates a situation that occurs when having a smaller value. t = 0 to V_TIncreases substantially more slowly than in FIG. I_pIs partially discharged to the first capacitor 31. However When switching off, V_TIs V in FIG. 3B._oThe jump indicated by Realize. From equation (2), this jump is V_iIt can't seem to get bigger You. The shade area, which is a measure of energy waste, is smaller than that of FIG. There is no. FIG. 3C shows the situation reached by the circuit shown in FIG. Jump V_oIs a shadow It has completely disappeared so that the area becomes negligibly small.   In the diagram shown in FIG. 1B, not only the auxiliary voltage but also the input voltage V_iEven from batteries Occur. This is appropriate for power supplies that must operate independently of the power line. It is a solution. However, if the device is connected to the power line, the power line voltage rectifier ( (Not shown) can be connected to the input terminals 1, 3 (FIG. 1A) and then rectified The transmission line voltage is smoothed by the input capacitor 5. In that case, the auxiliary voltage V_xIs re And from the battery, the solution shown in FIG. 1A is better. there Are the second capacitor 45, the third rectifying element 47 and the And the tap 49 of the third coil 9. Tap 49 is first Located approximately halfway through the coil 9 so that the voltage V across the second capacitor 45_x Is the voltage V across the input capacitor 5_iIs approximately equal to half.   FIG. 4 shows a second embodiment of the power supply device according to the present invention, and FIG. 4A is similar to FIG. 1A. , FIG. 4B is a circuit diagram similar to FIG. 1B. The corresponding parts are the corresponding references. Control numbers. In the circuit diagram of FIG. 4B, the auxiliary voltage source 55 is a power battery. It is arranged between the negative terminal 53 and the second coil 35. The situation of the first embodiment and Similarly, the voltage at the junction 43 is again at least the closed state of the switching element 11. V in state_ibe equivalent to. However, the voltage at junction 41 is now at most V_iTo Equally, because the second rectifying element 39 starts conducting at a higher voltage. This means that immediately before the switching element 11 closes, the voltage V_cIs equal to 0V Means lower. As soon as switching element 11 is closed, V₄₃Is 0V Become. V_c≤0V, so V₄₁≤V₄₃So that the switching element 11 is closed. Ruya V₄₁≦ 0V. Thus, at least V_xIs equal to the second coil 35 And this is at least V_xThe oscillation with the amplitude equal to And between the first capacitors 31. The voltage at junction 41 is Result from 0V to at least 2V_xWill increase. Therefore, the first capacitor 3 The voltage across 1 is then -2V_xIs equal to This means that the switching element Jumping voltage jumps again to V_i-2V_xMeans that it will be. V_xIs 1 / 2V_iThe voltage across the switching element 11 is thus again It will be zero at the switching off. Therefore, the same effect as in the first embodiment is exhibited. right.   In the circuit diagram shown in FIG. 4B, the auxiliary voltage source 55 is formed by a battery as shown in FIG. 1B. It is. FIG. 4A shows a third coil 65 connected between the negative input terminal 3 and the second coil 35. FIG. 2 shows a diagram of a specific embodiment in which an auxiliary voltage source is provided. The third coil 65 is For example, both coils are wound around the same soft magnetic core and magnetically connected to one coil 9. ing. This core may for example be formed by the core of the transformer 13. 3rd carp The connection between the coil 65 and the first coil 9 is given to the input terminals 1 and 3 of the first coil. Voltage pulses of the same polarity induce voltage pulses of the same polarity in the third coil. Selected. This is done in a conventional manner by the plurality of points in FIG. Is shown. The polarity of the voltage pulse induced in the second coil 15 of the transformer 13 is also It is shown in the same way. The number of turns of the third coil 65 is the number of turns of the first coil 9 And the voltage induced in the third coil is approximately half of the value of the input voltage. Halve.   The auxiliary voltage source is one of the two terminals of the second series connection 33 of the two embodiments described. Is provided for. This is the simplest solution from a connection technology point of view. However, placing the auxiliary voltage source in a different position in the second series connection 33 Is also possible.

────────────────────────────────────────────────── ─── [Continuation of summary] Undesirably high energy waste and disturbances in the switching element Voltage jumps that cause disturbances (electromagnetic interference, EMI) Prevents crossing of switching elements.

Claims (1)

[Claims] 1. A power supply device that converts an electrical DC voltage acting as an input voltage to an output voltage Positive and negative input terminals (1,3) arranged to receive an input voltage; At least a first coil (9) interconnecting both input terminals and a controllable switch. A first series connection (7) of the switching element (11) and a first capacitor (31). At least a second coil (35), a first rectifying element (37) and a second rectifying element (39). An amplitude limiting circuit (29) comprising: a second series connection (33); The column connection is such that the cathodes of the first and second rectifying elements are oriented towards the positive input terminal (1). Connected in parallel with the first series connection; one electrode of the first capacitor is connected to the second Connected to the anode of the rectifying element, while the other electrode is connected to the first coil and the switching element A power supply connected to the junction (43) of     The second series connection (33) also provides a series voltage equal to approximately half the input voltage. An auxiliary voltage source (55) arranged to supply a positive input terminal (1). A power supply device characterized in that it is directed to: 2. 2. The device according to claim 1, wherein the auxiliary voltage source is connected in a second series connection. 3) A power supply device located in one of the two terminals. 3. Device according to claim 2, wherein the auxiliary voltage source (55) is connected to a second rectifying element (3). 9) a second capacitor 45 connected between the cathode and the positive input terminal (1); The electrode of the second capacitor, which is connected to the cathode of the second rectifying element, also has a third rectifying element ( 47), and the cathode of the third rectifying element is located approximately in the middle of the first coil. Power supply device connected to the tap (49) of the first coil (9) to be placed. Place. 4. 3. The device according to claim 2, wherein the auxiliary voltage source (55) has a negative input terminal (3). ) And the second coil (35), and the first coil is connected to the input terminals (1, 3). A voltage pulse of a given polarity will induce a voltage pulse of the same polarity in the third coil. And a third coil (65) magnetically connected to the first coil (9). Characterized in that the number of turns of the coil is approximately half of the number of turns of the first coil. Source equipment.