DE102009028243A1 - Rectifier bridge circuit - Google Patents

Abstract

The invention relates to a rectifier bridge circuit (1), in particular for a motor vehicle generator, which has at least: a rectifier circuit (16) with at least two rectifying elements, between at least one phase connection (2, 3, 4) and two DC voltage connections (5, 6) are connected to output a DC voltage (B +), the rectifying elements Schottky diodes (10, 11; 12, 13; 14, 15) and / or active switches, e.g. B. are transistors, and a voltage limiting circuit (17) which contains a reverse-connected Zener diode (20). According to the invention, the voltage limiting circuit (17) has at least one series circuit (17-1, 17-2) comprising at least two Z diodes (20, 21; 22, 23). All diodes can be designed as press-in diodes.

Description

State of the art

Rectifier bridge circuits serve to rectify three-phase or multi-phase alternating current output by a generator. In motor vehicles in particular three-phase generators are used, whose output is below for the on-board voltage of z. B. 12 V is rectified. Rectifier bridges typically use B6 AC bridges with six silicon pn-type semiconductor diodes, commonly designed as Zener diodes, to provide a regulated breakdown for voltage limiting between the operating voltage terminals. In addition, other circuit elements are usually provided, for. B. an interference suppression capacitor and a voltage regulator, the rectified voltage to a certain value, for. B. 14.3 V stops. The Zener diodes are suitable for operation at high currents, eg. B. at current densities up to about 500 A / cm ² and designed at high temperatures. The falling at the Zener diodes in the flow direction forward voltage is at the high currents used about 1 V, the reverse current in the reverse direction up to the breakdown voltage, however, is very small and increases from the breakdown voltage sharply to prevent a voltage increase of the operating voltage above this value ,

The Breakdown voltages of those used in the rectifier bridge Z diodes are located above a 12 V electrical system of a vehicle the generator voltage in a range of z. B. 19 to 26 V, wherein the zener diodes are designed so that they briefly with very high Currents can be loaded in breakthrough and thereby the on-board net against surges at suddenly Protect increasing generator voltage. In addition to voltage fluctuations at the operating voltage terminals is in particular a Incident caused by a load dump (load dump) problematic in which the generator voltage of the connected generator at a sudden load change then rises sharply when a big one Load change occurs when the battery is disconnected or defective. As a result, very high voltages occur at the phase terminals or between the phase terminals and the operating voltage lines on.

disadvantageous At the pn-type semiconductor diodes, the forward voltage is too relative high passage losses and thus to a deterioration of the efficiency the bridge circuit and thus the entire generator assembly leads. As in the rectifier bridge in the middle always two diodes are connected in series, are the middle Leakage losses in a 100 A generator at about 200 W, where this power loss to a heating of the diodes and the rectifier leads and through costly cooling measures is to be reduced.

From the US 2005/0146309 A1 a generator arrangement for a vehicle is known, in which a B6 bridge of Schottky diodes is used as the rectifier bridge. The voltage is limited by a reverse-connected diode, which may be designed as a Zener diode. The Zener diode thus limits the operating voltage both against faults originating from the generator and against interference pulses which originate from the vehicle electrical system. Schottky diodes allow a smaller adjustment of the forward voltage than pn-diodes. A disadvantage, however, are their relatively high reverse currents, which contribute to a battery discharge and continue to increase sharply at high temperature. Thus, the maximum allowable power loss in breakthrough, z. B. in a load dump limited.

One further disadvantage when using an additional Zener diode for limiting the voltage is the temperature dependence their breakdown voltage. This dependence is particular relevant to the Avalance effect, where the breakdown voltage in Result of the temperature increase can increase sharply and thus also the positive operating voltage increases, which may be Damage to the electronics in the electrical system and the controller IC can lead to voltage regulation. Also, the training and integration of a correspondingly dimensioned Zener diode in the entire generator arrangement partly not without problems.

Disclosure of the invention

According to the invention in the voltage limiting circuit at least one series circuit used from at least two Zener diodes or Zener diodes. advantageously, This series circuit contains exactly two Zener diodes. in this connection can advantageously according to the invention Also, several such series circuits may be connected in parallel to to achieve appropriate dimensioning and, where appropriate to be able to catch higher currents. Consequently can be inventively z. B. four Zener diodes be used to dissipate sufficient power in the breakthrough to be able to, or more than four Z-diodes, z. Six or eight Zener diodes. The zener diodes themselves are in common Way as pn semiconductor diodes with a defined breakdown voltage educated. Preferably, its breakdown voltage is the same, in particular the Z diodes are designed identically to be as similar as possible To train properties.

The rectifier circuit according to the invention has rectifying elements which are formed by Schottky diodes and / or active switches. In particular, active switches can be used Transistors, preferably power MOSFETs are used. According to the invention thus z. B. a bridge circuit of six Schottky diodes possible, but it can also be one or more, in principle, all Schottky diodes are replaced by active switch.

According to the invention some advantages: Compared to the use of a single Z-diode allows the series connection that the breakdown voltage each Z-diode is about half smaller can be. According to the invention is advantageously exploited that for physical reasons, the temperature dependence or the temperature coefficient of the diodes with decreasing breakdown voltage sinks. In the series connection according to the invention of two Z-diodes with smaller, z. B. only half as big Breakdown voltages of the individual diodes can their temperature coefficients their breakdown voltage are kept low, so that the reverse current low in breakthrough, even at higher power losses remains. Thus, at a high load, for. B. a load dump or load shedding, the voltage increase of the series connection lower fail than with a single diode. Furthermore, the leakage current set lower between the operating voltage terminals than when using a single diode.

Though results according to the invention an additional Effort, because at least one additional Zener diode in the Voltage limiting circuit is provided. It is recognized, however, that this in a mounting situation using cooling plates and Einpressdioden also to simplify the circuit complexity can lead. When the operating voltage connections designed as cooling plates or with cooling plates can be connected according to the invention both the Schottky diodes of the rectifier device or rectifier bridge as also the Z-diodes of the voltage limiting circuit as Einpressdioden be formed. Thus, the bridge circuit by six trained as Einpressdioden Schottky diodes and the additional Voltage limiting circuit formed by two or four Zener diodes be used as Einpressdioden in the same metal plates as the Schottky diodes are pressed. This results in an advantageous Contacting or wiring situation in which the Z-diodes each Series connection in corresponding holes of the plus or minus metal plate be pressed and contacted in the same way become like the Schottky diodes of the bridge circuit. Here can a circuit board, which is for contacting the center taps the bridge circuit with the phase connections is provided, are also used for contacting the connection wires of the Z-diodes designed as Einpressdioden.

A Although such interconnection situation thus requires in principle a Z-diodes more, but allows a direct and simple wiring and contacting both the bridge circuit as well as the voltage limiting circuit.

By doing According to the invention, the two Zener diodes of each series circuit each used as Einpressdioden, results in a better Heat coupling and electrical contact. Especially can the performance occurring in the breakthrough case on the two press-in diodes dissipated better than heat are called z. B. via a single press-in diode.

Consequently comes with relatively little additional hardware overhead and production costs a good heat coupling and advantageous Installation situation achieved.

The Center taps of the series circuits of the Z diodes can also be contacted with each other, creating in this area a additional cooling mass is formed for temperature absorption. Furthermore, this is a contact with z. B. a star point of the connected alternator possible.

Brief description of the drawings

1 shows a circuit diagram of a rectifier bridge circuit according to the invention according to a first embodiment;

2 shows a circuit diagram of a rectifier bridge circuit according to another embodiment;

3 shows a cross section through a portion of the rectifier bridge circuit to illustrate the installation situation of the diodes;

4 shows a corresponding cross-section in a simplified representation by the rectifier bridge circuit 1 ,

Description of the embodiments

A rectifier bridge circuit 1 according to 1 respectively. 101 according to 2 has three phase connections 2 . 3 and 4 for the phases U, V, W of an example in 2 shown alternator 40 with three alternating voltage sources 40-1 . 40-2 . 40-3 on, wherein the phases U, V, W are phase-shifted in a conventional manner by 120 °. The alternator 40 forms with the rectifier bridge circuit 1 or 101 thus a generator arrangement 41 to issue a match voltage B + from z. B. 12 V DC voltage connections 5 and 6 , in particular for use in a vehicle, eg. B. motor vehicle, which, unlike shown here, more than three phases U, V, W can be provided.

The rectifier bridge circuit 1 . 101 thus provides a positive terminal or an operating voltage connection 5 the DC voltage B + to a ground terminal 6 to disposal. Advantageously, in addition, a voltage regulator, not shown, as well as a suppression capacitor between the operating voltage connection 5 and the ground connection 6 switched, which are known as such and therefore will not be further described here.

The rectifier bridge circuits 1 and 101 each have a rectifier circuit 16 and a voltage limiting circuit 17 respectively. 117 on, the rectifier circuit 16 each as a B6 bridge 16 with six rectifying Schottky diodes 10 to 15 is formed, as the rectifier diodes between the operating voltage terminal 5 and the ground connection 6 are switched and their center taps 9-1 . 9-2 . 9-3 to the phase connections 2 . 3 . 4 are connected. The Schottky diodes 10 . 12 and 14 put here plus diodes, according to the Schottky diodes 11 . 13 and 15 Minus diodes in the usual bridge circuit is.

The breakdown voltage UD of the Schottky diodes 12 to 15 is z. B. at about 40 V. The Schottky diodes 10 to 15 contain in addition to the actual Schottky contact or metal semiconductor contact advantageously further structures for reducing the reverse current. In particular, they can be designed as trench MOS Schottky Barrier Diodes (TMBS).

According to the invention, the voltage limiting circuit 17 of the 1 at least one series circuit 17-1 . 17-2 of at least two Zener diodes 20 . 21 respectively. 22 . 23 between the operating voltage connection 5 and the ground connection 6 on. Advantageously, each series connection 17-1 and 17-2 exactly two Z-diodes 20 . 21 such as 22 . 23 on. As in 1 and 2 shown according to the invention a parallel connection of two or more series circuits 17-1 and 17-2 from two Z-diodes each 20 . 21 such as 22 . 23 be provided. The Z-diodes 20 . 21 . 22 . 23 are in the usual way in the reverse direction between the operating voltage connection 5 and the ground connection 6 switched, ie in the same direction as the Schottky diodes 10 to 15 , The total breakdown voltage of the voltage limiting circuit 17 thus becomes for each of the series circuits 17-1 and 17-2 by the sum of the breakdown voltages UZ of the individual Zener diodes 20 . 21 respectively. 22 . 23 educated. Advantageously, the Z-diodes 20 to 23 designed identically, so that correspondingly the breakdown voltage of the two series circuits 17-1 and 17-2 is equal to and is twice the breakdown voltage UZ of a Zener diode 20 to 23 results. The breakdown voltage UZ of each Zener diode 20 to 23 can z. B. between 10 and 14 V, z. B. 12 V amount.

In normal operation of the generator 40 the rectification of the three-phase current or the alternating current of the three phases U, V and W takes place via the B6 bridge 16 from the six Schottky diodes 10 to 15 , Through the Z-diodes 20 . 21 . 22 . 23 only a small reverse current flows.

In case of failure of a sudden overvoltage, the voltage limiting circuit 17 to become active. In the most relevant case of a sudden load dump (load dump), the current I flows in the B6 bridge 16 still some time of z. B. 100 to 400 ms on. But since no current flow through the loads is more possible, which increases at the phases or at one of the phases U, V, W and thus at least one of the phase terminals 2 . 3 . 4 applied generator voltage up to the total breakdown voltage 2 * UZ of the voltage limiting circuit 17 at. When reaching 2 * UZ, the voltage is applied through the voltage limiting circuit 17 limited. During this period, a high current flows through the Z-diodes 20 to 23 while through the Schottky diodes 10 to 13 furthermore only one flow current IS flows.

In the embodiment of the 1 are the two series connections 17-1 and 17-2 the voltage limiting circuit 17 only via the two DC voltage connections 5 and 6 , but not connected in center taps. In the embodiment of the 2 are in the voltage limiting circuit 117 otherwise unchanged structure, the two series circuits 17-1 and 17-2 in their middle taps 18-1 and 18-2 interconnected so that the cathodes of the zener diodes 20 and 22 and correspondingly the anodes of the Z-diodes 21 and 23 with each other through a connection 19 are contacted. By this additional contact on the one hand, the mass or current-carrying ground of the voltage limiting circuit 117 increased, so that more mass to reduce the temperature is present. Furthermore, if necessary, the safety in case of impairment of a Zener diode 20 to 23 be elevated.

When in the embodiment of the 2 the alternator 40 as Stemschaltung of three AC sources 40-1 . 40-2 and 40-3 is switched, the common center tap 18-1 and 18-2 or the connection 19 the four Zener diodes 20 to 23 the current limiting circuit 117 to the star point 42 of the alternator 40 be connected.

Furthermore, in all embodiments, one or more Schottky diodes 10 to 15 be replaced by active switches, in particular power MOSFETs.

According to the invention, in particular also further series connections corresponding 17-1 and 17-2 each of two Zener diodes are connected in parallel, ie, three or more series circuits of two Zener diodes each are selected. In particular, the number of Zener diodes or of the series circuits can be selected to such an extent that the power expected in a breakdown case can be dissipated by the Z diodes in each case. According to the invention, the power in the breakdown, in particular in a load shedding or even when interference voltages from the electrical system on all Z-diodes 20 to 23 and optionally further Z diodes distributed, so that the heat dissipation distributed over several locations and in particular the heat dissipation through the heat sink is facilitated.

The reverse current of the entire rectifier bridge circuit 1 results from the sum of the reverse currents through the B6 bridge 16 and the voltage limiting circuit 17 respectively. 117 , The breakdown voltage UZ of the Z diodes is half the breakdown voltage of the entire voltage limiting circuit 17 respectively. 117 , so that the temperature coefficient of the breakdown voltage UZ and thus the increase of the breakdown voltage UZ at a temperature increase in particular in the Avalance effect is low, so that at the operating voltage connection 5 applied Bebtriebsspannung B + even at a temperature increase not z. B. rises above 33 volts. According to the invention, the reverse currents through the voltage limiting circuit 17 or 117 low, since the Z-diodes used in the invention 20 to 23 have low reverse currents due to their low breakdown voltage UZ.

The 3 and 4 show advantageous installation situations. According to the invention, all diodes, ie both the Schottky diodes 10 to 15 as well as the Z-diodes 20 to 23 , as press-fit diodes 24 and 34 be formed. According to 3 becomes a first press-in diode 24 in the plus metal plate 5a pressed in, the operating voltage connection 5 represents or is connected to this, and corresponding to a second press-in diode 34 in a minus metal plate 6a Pressed in, the ground connection 6 represents or is connected to this.

One connection of the respective press-in diode 24 and 34 is as a connecting wire 25 respectively. 35 led out and the other connection as a round or cylindrical diode housing, in particular as a metal base 26 . 36 formed into a hole 27 . 37 the respective metal plate 5a . 6a is pressed. This will provide a good thermal and electrical connection between the metal base 26 . 36 and the respective metal plate 5a . 6a reached. In principle, both the anode and the cathode of each diode can be used as a metal base 26 . 36 form. Thus, as the first press-in diode 24 the plus Schottky diodes 10 . 12 . 14 as well as the Z-diodes 21 and 23 be formed, with their cathodes through the connecting wire 25 are formed, and accordingly as a second press-in diode 24 the minus Schottky diodes 11 . 13 . 15 as well as the Z-diodes 20 . 22 , their anodes through the connecting wire 35 are formed. The symbols on the right in 3 show these two interconnections. According to 3 can the connecting wires 25 and 35 the two series-connected press-in diodes 25 . 35 each be contacted with each other, which is relevant for all Z-diodes and Schottky diodes. Furthermore, the connecting wires 25 and 35 in a center tap with a lead wire 30 Being contacted on a circuit board 32 is guided; this is for the Schottky diodes 10 to 15 as well as the Z-diodes 20 to 23 of the 2 relevant.

According to 4 can according to the invention, the entire diode array, ie all Schottky diodes 10 to 15 the B6 bridge 16 as well as all Z-diodes 20 to 23 the voltage limiting circuit 17 or 117 , as press-in diodes between the common plus metal plate 5a and the common minus metal plate 6a be switched, which also serve as a heat sink. The three center taps 9-1 . 9-2 . 9-3 the B6 bridge 16 are over lead wires 30a . 30b . 30c contacted in 4 schematized and in the common wiring plate 32 are guided. The connecting wires 25 and 35 the Z-diodes 20 to 23 are like in 4 shown according to the embodiment of the 1 not contacted further; nevertheless, the wiring board can 32 the connecting wires 25 . 35 record in isolation. In the embodiment of the 2 is corresponding in the wiring plate 32 between the center taps 18-1 and 18-2 ie on the connecting wires 25 and 35 the four Zener diodes 20 to 22 , a lead wire as a connection 19 connected.

Thus, according to 4 a very compact and cost-effective, robust construction with very good cooling and electrical contacting of all diodes.

The rectifier bridge circuit according to the invention is particularly advantageous for the three-phase generator 40 suitable for rectification to an on-board voltage B + of 12 V. Farther However, it can also be used for other purposes or connected to other generators, eg. B. 28 V generators. In this case, the relationship that is advantageous for all temperatures and currents advantageously applies UZ <0.5 · (UD-UFS), where UZ is the breakdown voltage of the Z diodes, UD is the breakdown voltage of the Schottky diodes, and UFS is the forward voltage of the Schottky diodes.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• US 2005/0146309 A1 [0004]

Claims (15)

Rectifier bridge circuit ( 1 . 101 ), in particular for a motor vehicle generator ( 40 ) comprising at least: a rectifier circuit ( 16 ) with at least two rectifying elements ( 10 . 11 ; 12 . 13 ; 14 . 15 ) between at least one phase connection ( 2 . 3 . 4 ) and two DC connections ( 5 . 6 ) are connected to the output of a DC voltage (B +), wherein the rectifying elements Schottky diodes ( 10 . 11 ; 12 . 13 ; 14 . 15 ) and / or active switches, and a voltage limiting circuit ( 17 . 117 ), which is a reverse-connected Zener diode ( 20 ), characterized in that the voltage limiting circuit ( 17 . 117 ) at least one series circuit ( 17-1 . 17-2 ) of at least two Z-diodes ( 20 . 21 ; 22 . 23 ) having. Rectifier bridge circuit according to claim 1, characterized in that the voltage limiting circuit ( 17 . 117 ) at least two series connections ( 17-1 . 17-2 ) each having at least two Z-diodes ( 20 . 21 ; 22 . 23 ) exhibit. Rectifier bridge circuit according to claim 2, characterized in that center taps ( 18-1 . 18-2 ) between the at least two Zener diodes ( 20 . 21 ; 22 . 23 ) of the series circuits ( 17-1 . 17-2 ) of the voltage limiting circuit ( 117 ) via a connection ( 19 ) are contacted. Rectifier bridge circuit according to one of the preceding claims, characterized in that it comprises three phase connections ( 2 . 3 . 4 ) for phases (U, V, W) of a three-phase generator ( 40 ) and the rectifier device as a bridge of at least six rectifying elements ( 10 . 11 . 12 . 13 . 14 . 15 ) are formed, each between a phase terminal ( 2 . 3 . 4 ) and one of the two DC voltage connections ( 5 . 6 ) are switched. Rectifier bridge circuit according to one of the preceding claims, characterized in that it is designed such that the sum of the breakdown voltages (UZ) of the Z diodes ( 20 . 21 ; 22 . 23 ) of a series circuit ( 17-1 . 17-2 ) of the voltage limiting circuit ( 17 . 117 ) for all current values and temperature values of an operating region of the rectifier bridge circuit is in each case smaller than the breakdown voltage (UD) of the rectifying elements (UD) which is reduced by one forward voltage (UFS) ( 10 . 11 . 12 . 13 . 14 . 15 ), Rectifier bridge circuit according to one of the preceding claims, characterized in that the Z-diodes ( 20 . 21 ; 22 . 23 ) are formed identically. Rectifier bridge circuit according to one of the preceding claims, characterized in that a breakdown voltage (UD) of the rectifying elements (UD) 10 . 11 . 12 . 13 . 14 . 15 ) of the rectifier bridge ( 16 ) in the range of 34 to 46 V and the breakdown voltages (UZ) of the Z-diodes ( 20 . 21 ; 22 . 23 ) of the voltage limiting circuit ( 17 . 117 ) are between 11 and 14 V, whereby at the DC voltage connections ( 5 . 6 ) is output a DC voltage (B +) of 12 V for a vehicle electrical system of a vehicle. Rectifier bridge circuit according to one of the preceding claims, characterized in that at least one Schottky diode ( 10 . 11 . 12 . 13 . 14 . 15 ) is designed as a TMBS diode. Rectifier bridge circuit according to one of the preceding claims, characterized in that as an active switch of the rectifier circuit ( 16 ) between a phase connection ( 2 . 3 . 4 ) and a DC voltage connection ( 5 . 6 ) at least one transistor, in particular a power MOS field effect transistor is provided. Rectifier bridge circuit according to one of the preceding claims, characterized in that at least one diode ( 10 . 11 . 12 . 13 . 14 . 15 ; 20 . 21 ; 22 . 23 ) as a press-in diode ( 24 . 34 ) is formed, the two terminals as a diode housing ( 26 . 36 ), in particular metal base ( 26 . 36 ), and as a connecting wire ( 25 . 35 ) are formed, wherein the diode housing ( 26 . 36 ) into a hole ( 27 . 37 ) as a DC voltage connection ( 5 . 6 ) or with a DC voltage connection ( 5 . 6 ) connected metal plate ( 5a . 6a ) is pressed. Rectifier bridge circuit according to claim 10, characterized in that the Schottky diodes ( 10 . 11 . 12 . 13 . 14 . 15 ) of the rectifier circuit ( 16 ) and at least the Z-diodes ( 20 . 21 . 22 . 23 ) of a series circuit ( 17-1 . 17-2 ) of the voltage limiting circuit ( 17 . 117 ) as press-in diodes ( 24 . 34 ) are formed, each in a plus-metal plate ( 5a ) or in a minus metal plate ( 6a ) are pressed in, with their connecting wires ( 25 . 35 ) in at least one interconnection plate ( 32 ) are contacted with each other, wherein at least the center taps ( 9-1 . 9-2 . 9-3 ) of the rectifier circuit ( 16 ) via one in or on the interconnection plate ( 32 ) guided line ( 30a , b, c) to a respective phase connection ( 2 . 3 . 4 ) connected. Rectifier bridge circuit according to claim 11, characterized in that all Schottky diodes ( 10 . 11 . 12 . 13 . 14 . 15 ) the same judge circuit ( 16 ) and all Z-diodes ( 20 . 21 ; 22 . 23 ) of the voltage limiting circuit ( 17 . 117 ) in each case in the common Plus metal plate ( 5a ) or the common negative metal plate ( 6a ) are pressed. Rectifier bridge circuit according to claim 12, characterized in that the connecting wires ( 25 . 35 ) of the Z-diodes ( 20 . 21 ; 22 . 23 ) of the at least one series circuit ( 17-1 . 17-2 ) in the circuit board ( 32 ) are contacted with each other. Rectifier bridge circuit according to claim 13 and claim 3, characterized in that the center taps ( 18-1 . 18-2 ) of the at least two series circuits ( 17-1 . 17-2 ) in the circuit board ( 32 ) are contacted with each other. Generator arrangement ( 41 ), in particular for a motor vehicle, comprising: an alternator ( 40 ) with three alternating voltage sources ( 40-1 . 40-2 . 40-3 ) in star connection, and a rectifier bridge circuit ( 101 ) according to claim 3 or 14, characterized in that the center taps ( 18-1 . 18-2 ) of the at least two series circuits ( 17-1 . 17-2 ) with a star point ( 42 ) of the alternator ( 40 ) are connected.

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