DE102019218893B4 - Step-up converter and method for operating a step-up converter - Google Patents

Abstract

Boost converter (1), comprising a voltage connection (2) for a positive potential and a voltage connection (3) for a negative potential of an energy store (40) and a voltage connection (4) for a positive potential and a voltage connection (5) for a negative potential an energy source (50), the two voltage connections (3, 5) for the negative potential being connected to one another, the step-up converter (1) having at least two half-bridge circuits (10) connected in parallel, each half-bridge circuit (10) having at least one upper circuit breaker (T1) and at least one lower circuit breaker (T2), a first overcurrent fuse (F1) being arranged between the upper circuit breaker (T1) and the voltage connection (2) for the positive potential and between the lower circuit breaker (T2) and a second overcurrent fuse (F2) is arranged on the voltage connection (3) for the negative potential, wherein the center taps (M) of the half-bridge circuits (10) are connected via at least one inductance (L) to the voltage connection (4) for the positive potential of the energy source (50), being parallel to the series connection of the upper circuit breaker (T1) and the lower circuit breaker (T2) and second overcurrent fuse (F2) a further first circuit breaker (Th1) is arranged in series with a capacitor (C) and parallel to the series connection of the first overcurrent fuse (F1), upper circuit breaker (T1) and lower circuit breaker (T2) another second power switch (Th2) is arranged in a row with a capacitor (C).

Description

The invention relates to a step-up converter and a method for operating a step-up converter.

Boost converters are required to convert a low input voltage into a higher output voltage. One area of application is, for example, charging a high-voltage battery in a traction network of a motor vehicle from a fuel cell, an external charging station or a battery with a lower nominal voltage than the high-voltage battery.

There are various topologies for boost converters, with half-bridge circuits being used in one embodiment. Such designs have the advantage, on the one hand, that they can be easily parallelized, so that the ripple that occurs when converting can be better compensated for. Furthermore, versions are possible where the half-bridge circuits can take on several functions. For example, from the US 2016/0 226 396 A1 a step-up converter is known which consists of two half bridges with semiconductor power switches, the lower and upper branches of each half bridge being equipped with a fuse, and the connection point of the two semiconductor power switches of each half bridge being connected to the positive pole of an energy source via an inductance . Furthermore, from de DE 11 2013 007 105 T5 r a boost converter is known that boosts a voltage of an energy source and delivers it to an energy storage device, the boost converter consisting of a single half-bridge circuit of semiconductor power switches and the half-bridge circuit having a fuse between the lower semiconductor switch and ground, and the connection point of the two semiconductor Circuit breaker is connected to the positive pole of an energy source via an inductance. Finally it's over WELCHKO, BA et al .: Fault tolerant threephase AC motor drive topologies: a comparison of features, cost, and limitations. In: IEEE Transactions on Power Electronics, Vol. 19, July 2004, No. 4, pp. 1108-1116 known to supply an inverter with a direct voltage energy source, the inverter having several half-bridge circuits that are connected in parallel, each half-bridge circuit having at least one upper power switch and at least one lower power switch, wherein between the upper power switch and the voltage connection for the positive potential of the Energy source is a first overcurrent fuse and a second overcurrent fuse is arranged between the lower circuit breaker and the voltage connection for the negative potential of the energy source, a further first circuit breaker being arranged in series with a capacitor parallel to the series connection of the upper circuit breaker, lower circuit breaker and second overcurrent fuse and parallel to the series connection of the first overcurrent fuse, upper circuit breaker and lower circuit breaker, another second circuit breaker in one Series is arranged with a capacitor.

One problem with such half-bridge circuits is that in the event of a short circuit between positive potential and negative potential in a half-bridge circuit, the entire step-up converter must be switched off.

The invention is based on the technical problem of creating a step-up converter in which the availability is improved, as well as providing a method for operating a step-up converter.

The solution to the technical problem results from a step-up converter with the features of claim 1 and a method for operating a step-up converter with the features of claim 8. Further advantageous embodiments of the invention emerge from the subclaims.

For this purpose, the step-up converter comprises a voltage connection for a positive potential and a voltage connection for a negative potential of an energy store as well as a voltage connection for a positive potential and a voltage connection for a negative potential of an energy source, the two voltage connections for the negative potential being connected to one another. The step-up converter has at least two half-bridge circuits that are connected in parallel, each half-bridge circuit having at least one upper circuit breaker and at least one lower circuit breaker, a first overcurrent fuse being arranged between the upper circuit breaker and the voltage connection for the positive potential and between the lower circuit breaker and A second overcurrent fuse is arranged on the voltage connection for the negative potential, the center taps of the half-bridge circuits being connected via at least one inductance to the voltage connection for the positive potential of the energy source. In parallel to the series connection of the upper circuit breaker, lower circuit breaker and second overcurrent fuse, another first circuit breaker is arranged in series with a capacitor and, parallel to the series circuit of the first overcurrent fuse, upper circuit breaker and lower circuit breaker, another second circuit breaker is arranged in series with a capacitor. By the further first circuit breaker or the further second Circuit breakers can specifically generate an overcurrent that triggers the assigned overcurrent fuse quickly and reliably, so that a faulty half-bridge circuit is galvanically isolated from the potential line.

By means of the capacitor connected in series, parasitic inductances are specifically compensated so that the current rise is very fast, so that energy is converted in the overcurrent protection sufficiently quickly to trigger it. This means that the overcurrent protection can be triggered within one clock cycle. The capacitance of the capacitor is designed for the characteristic values of the overcurrent protection and the parasitic inductances. The capacity is designed to be as low as possible in order to save chip space. It should be noted that tripping can take place in a targeted manner without another overcurrent fuse having already tripped. The overcurrent fuse is designed, for example, as a fuse, bonding wire or conductor track.

In this case, the half-bridge circuits connected in parallel are preferably actuated offset, so that the ripples of the output voltage partially compensate each other.

In one embodiment, each half-bridge circuit is connected to the voltage connection for the positive potential of the energy source via its own inductance, so that even individual faults in an inductance do not lead to total failure.

In an alternative embodiment, the step-up converter comprises at least four half-bridge circuits, the center taps of two half-bridge circuits having a common inductance being connected to the voltage connection for the positive potential of the energy source. This halves the number of inductances, and the step-up converter can continue to operate even if one inductance fails. This makes use of the fact that the failure of a passive inductance is very unlikely. In principle, more than two half-bridge circuits can also share one inductance, with all half-bridge circuits sharing only a single inductance in the extreme case.

In a further embodiment, a capacitor is arranged parallel to the voltage connections for the energy store and / or parallel to the voltage connections for the energy source. The capacitor on the energy store serves as an intermediate circuit capacitor and smooths the output voltage. The capacitor at the energy source serves primarily as a filter against high-frequency interfering components.

The upper and lower power switches are preferably designed as MOSFETs.

In a further embodiment, the upper circuit breakers and the lower circuit breakers are each assigned a current and / or temperature sensor, so that an impending defect can be detected at an early stage. Both sensors are preferably used. Current and temperature sensors can be integrated into the circuit breakers or they can be separate sensors. A current sensor is also preferably assigned to a center tap of the half-bridge.

In a further embodiment, the further first power switch and the further second power switch are designed as thyristors. These have a good blocking ability and can switch large currents quickly.

In a further embodiment, the half-bridge modules are each designed as an integrated chip.

In a further embodiment, the first and second overcurrent fuses are designed as a conductor track or bonding wire, so that these can be implemented particularly easily in one chip.

The method for operating a step-up converter includes that in the event of a fault or an impending fault in a circuit breaker, the associated additional circuit breaker is switched through in order to trigger the associated overcurrent protection in order to galvanically separate the defective circuit breaker from the potential of the energy store within one clock cycle. The affected half-bridge circuit can then be switched off and the step-up mode can be continued with the remaining half-bridge circuits. It can be provided that the step-up converter is operated with a correspondingly reduced power. Alternatively, it can be provided that the remaining half-bridge circuits are operated at least temporarily with increased power in order to compensate for the failure of one half-bridge circuit. This can be signaled to the motor vehicle driver so that he can, for example, drive to a workshop to replace the defective half-bridge circuit.

In a further embodiment, after the overcurrent fuse has been triggered, the other overcurrent fuse of the half-bridge circuit is also triggered as a precaution.

• 1 eine Schaltungsanordnung eines Hochsetzstellers in einer ersten Ausführungsform,
• 2 eine Schaltungsanordnung eines Hochsetzstellers in einer zweiten Ausführungsform und
• 3 einen Leistungsschalter mit Sensoren.

The invention is explained in more detail below on the basis of preferred exemplary embodiments. The figures show:

• 1 a circuit arrangement of a step-up converter in a first embodiment,
• 2 a circuit arrangement of a step-up converter in a second embodiment and
• 3 a circuit breaker with sensors.

In the 1 is a boost converter 1 shown in a first embodiment. The boost converter 1 includes a voltage connection 2 for a positive potential and a voltage connection 3 for a negative potential of an energy store 40 as well as a voltage connection 4th for a positive potential and a voltage connection 5 for a negative potential of an energy source 50 , the two voltage connections 3 , 5 for the negative potential are connected to each other. Here is the nominal voltage of the energy source 50 less than the nominal voltage of the energy storage 40 . The energy storage 40 is for example a high-voltage battery with a nominal voltage of 800 V and the energy source 50 is for example a fuel cell or a battery with a nominal voltage between 200 V to 300 V. Furthermore, the step-up converter 1 still connections 6th for other high-voltage components 60 on.

The boost converter 1 has six half-bridge circuits 10 which are connected in parallel, each half-bridge circuit 10 at least one upper circuit breaker T1 and at least one lower circuit breaker T2 having. These are also known as high-side and low-side switches. In parallel with the circuit breakers T1 , T2 are each free wheeling diodes D. arranged. Between the upper circuit breaker T1 and the voltage connection 2 A first overcurrent protection is required for the positive potential F1 arranged, which is preferably designed as a correspondingly dimensioned conductor track or bonding wire. Correspondingly is between the lower circuit breaker T2 and the connection 3 a second overcurrent fuse for the negative potential F2 arranged, which is also preferably designed as a conductor track or bonding wire. The tapping of funds M. the half-bridge circuit 10 is in each case via an inductance L. with the voltage connection 4th for the positive potential of the energy source 50 connected. Next is parallel to the series connection of the upper circuit breaker T1 , lower circuit breaker T2 and a second overcurrent fuse, a further first circuit breaker Th ₁ in series with a capacitor C. arranged and parallel to the series connection of the first overcurrent fuse F1 , upper circuit breaker T1 and lower circuit breaker T2 another second circuit breaker Th ₂ in series with a capacitor C. arranged. Parallel to the voltage connections 2 , 3 of the energy storage 40 is at least one capacitor C _dc and parallel to the voltage connections 4th , 5 the energy source is at least one capacitor C _LS arranged. The upper circuit breakers can then be controlled by a control unit (not shown) T1 and lower circuit breaker T2 can be controlled in such a way that the voltage between the voltage connections 4th , 5 to a higher voltage between the voltage connections 2 , 3 is converted. Thereby the half-bridge circuits 10 preferably controlled at a time offset from one another, so that ripples appearing on the capacitor C _dc do not overlay.

The circuit breakers T1 , T2 are current sensors 7th and temperature sensors 8th assigned their data from the control unit 30th or another unit, so that an error or an impending error (such as a failure) can be detected at an early stage (see also 3 ). This is for example in 1 by a cross on the upper circuit breaker T1 the left half-bridge circuit 10 symbolizes. In this case the control unit controls 30th or another unit the associated further first circuit breaker Th ₁ so that a large tripping current flows, which is the first overcurrent protection F1 triggers, the current flow is shown in dashed lines. Then the second overcurrent protection can be used F2 be triggered by the further second circuit breaker Th ₂ is controlled, but this is not mandatory. The left half-bridge circuit 10 can then be switched off or is no longer activated, with the defective half-bridge circuit due to the galvanic separation 10 no effect on the rest of the step-up converter 1 has. The remaining half-bridge circuits 10 can then be controlled as before, or they are controlled in a modified manner so that the time offset in the control is constant again. It can also be provided that the current via the individual half-bridge circuits 10 is increased, so as to reduce the power loss of the disconnected half-bridge circuit 10 to compensate.

In the 2 is an alternative embodiment for a boost converter 1 shown, wherein the same elements are provided with the same reference numerals. In contrast to 1 share two half-bridge circuits 10 an inductance L. , including the two center taps M. are connected to each other. Thus, the number of passive inductances can be halved. This makes use of the fact that the probability of failure of passive inductances is considerably lower than that of semiconductor electronic components.

The half-bridge circuits 10 are preferably designed as integrated chips, so that in the event of a defect in a half-bridge circuit 10 only the chip has to be replaced.

List of reference symbols

1

Boost converter

2

Voltage connection

3

Voltage connection

4th

Voltage connection

5

Voltage connection

6th

connections

7th

Current sensors

8th

Temperature sensors

10

Half-bridge circuit

30th

Control unit

40

Energy storage

50

Energy source

60

High-voltage component

T1

upper circuit breaker

T2

lower circuit breaker

F1

first overcurrent protection

F2

second overcurrent protection

Th1

another first circuit breaker

Th2

another second circuit breaker

C.

capacitor

Cdc

capacitor

CLS

capacitor

L.

Inductance

M.

Fund tapping

D.

Freewheeling diode

Claims (9)

Boost converter (1), comprising a voltage connection (2) for a positive potential and a voltage connection (3) for a negative potential of an energy store (40) and a voltage connection (4) for a positive potential and a voltage connection (5) for a negative potential an energy source (50), the two voltage connections (3, 5) for the negative potential being connected to one another, the step-up converter (1) having at least two half-bridge circuits (10) connected in parallel, each half-bridge circuit (10) having at least one upper circuit breaker (T1) and at least one lower circuit breaker (T2), a first overcurrent fuse (F1) being arranged between the upper circuit breaker (T1) and the voltage connection (2) for the positive potential and between the lower circuit breaker (T2) and a second overcurrent fuse (F2) is arranged on the voltage connection (3) for the negative potential, wherein the center taps (M) of the half-bridge circuits (10) are connected via at least one inductance (L) to the voltage connection (4) for the positive potential of the energy source (50), being parallel to the series connection of the upper circuit breaker (T1) and the lower circuit breaker (T2) and second overcurrent fuse (F2) a further first circuit breaker (Th ₁ ) is arranged in series with a capacitor (C) and parallel to the series connection of the first overcurrent fuse (F1), upper circuit breaker (T1) and lower circuit breaker (T2) a further second power switch (Th ₂ ) is arranged in a row with a capacitor (C). Boost converter after Claim 1 , characterized in that each half-bridge circuit (10) is connected to the voltage connection (4) for the positive potential of the energy source (50) via its own inductance (L). Boost converter after Claim 1 , comprising at least four half-bridge circuits (10), the center taps (M) of the second half-bridge circuits (10) being connected with a common inductance (L) to the voltage connection (4) for the positive potential of the energy source (50). Step-up converter according to one of the preceding claims, characterized in that a capacitor (C _dc , C _LS ) is arranged. Step-up converter according to one of the preceding claims, characterized in that the upper power switch (T1) and the lower power switch (T2) are each assigned a current sensor (7) and / or temperature sensor (8). Step-up converter according to one of the preceding claims, characterized in that the further first power switch (Th ₁ ) and the further second power switch (Th ₂ ) are designed as thyristors. Step-up converter according to one of the preceding claims, characterized in that the half-bridge circuits (10) with the associated further power switches (Th ₁ , Th ₂ ) are each designed as an integrated chip. Method for operating a step-up converter (1) with the features of Claim 1 , thereby characterized in that in the event of a fault or an impending fault in a circuit breaker (T1, T2) of a half-bridge circuit (10), the associated additional circuit breaker (Th ₁ , Th ₂ ) is switched through in order to trigger the associated overcurrent fuse (F1, F2). Procedure according to Claim 8 , characterized in that then the other overcurrent fuse (F2, F1) of the half-bridge circuit (10) is triggered.

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