DE102018206269A1 - DC-DC converter, vehicle electrical system with a DC-DC converter - Google Patents

Abstract

Disclosed is a DC-DC converter (GW), comprising: - a primary-side power connection (SA1) for connecting the DC-DC converter (GW) to a first voltage (U1), - a secondary-side electrical connection (SA2) for connecting the DC-DC converter (GW) to a second voltage (U2), - a ground power terminal (MA) for connecting the DC-DC converter (GW) to an electrical ground (GND), - a converter circuit (WS) between the primary-side (SA1) and secondary-side (SA2) power terminals for converting between the first (SA) U1) and the second (U2) voltage, - a single ground-side reverse-connection protection switch (K5) which is electrically connected in a ground current path (MP) between the converter circuit (WS) and the ground power connection (MA), - a single primary-side disconnecting switch (K1) and / or a single secondary-side disconnect switch (K2), wherein the single primary-side disconnect switch (K1) in a primary-side converter current path (WP1) between the primary-side power terminal (SA1) and the converter circuit (WS), and / or the single secondary-side disconnect switch (K2) in a secondary-side converter current path (WP2) between the converter circuit (WS) and the secondary-side power terminal (SA2) electrically connected are.

Description

Technical area:

The present invention relates to a DC-DC converter and a vehicle electrical system, esp. Of a motor vehicle, with a DC-DC converter.

State of the art and object of the invention:

DC-DC converters for unidirectional / bidirectional conversion between different voltages of multi-voltage systems are known and are used, inter alia, in multi-voltage on-board networks of motor vehicles, especially of hybrid electric / electric vehicles, for converting between different on-board voltages.

The aim is to perform with the DC-DC converters in addition to the voltage conversion additional protection functions to z. B. circuit components of multi-voltage systems or multi-voltage systems to protect against damage caused by surges, overcurrents and / or reverse polarity.

In addition, it is generally desired to manufacture the DC-DC converter as inexpensively as possible.

Thus, the object of the invention is to provide a cost-effective and at the same time safe DC-DC converter.

Description of the invention:

This object is solved by subject matters of the independent claims. Advantageous embodiments are the subject of the dependent claims.

According to a first aspect of the invention, a unidirectional / bidirectional DC-DC converter, in particular for a multi-voltage vehicle electrical system of a motor vehicle, especially a hybrid electric / electric vehicle, is provided.

The DC-DC converter comprises a primary-side power connection for connecting the DC-DC converter to a first voltage, for example to a first vehicle electrical system voltage of a first electrical system branch of the multi-voltage vehicle electrical system.

The DC-DC converter further comprises a secondary-side power connection for connecting the DC-DC converter to a second voltage, for example to a second vehicle electrical system voltage of a second vehicle electrical system branch of the multi-voltage vehicle electrical system.

The DC-DC converter also includes a ground power connection for connecting the DC-DC converter to an electrical ground, for example, to the mass KL31 of the motor vehicle.

The DC-DC converter further includes a converter circuit for converting between the first and second voltages electrically connected between the primary side and the secondary side power terminals.

The DC-DC converter further comprises a, in particular single, ground-side controllable reverse polarity reversal protection switch for reverse polarity protection, which is electrically connected in a ground current path between the converter circuit and the ground power connection.

The DC-DC converter further comprises a single, primary-side disconnect switch and / or a single, secondary-side disconnect switch, the primary-side disconnect switch being electrically connected in a primary-side converter current path between the primary-side power terminal and the converter circuit, and / or the secondary-side disconnect switch in a secondary-side converter current path between the converter circuit and the secondary side power connector is electrically connected.

Here, the converter circuit is, for example, as one of the known in the art converter stages, esp. With one or more half-bridge circuit units formed.

The two circuit breakers and the polarity reversal protection switch are not concerned with switches of a half-bridge circuit unit, which are cyclically, eg. With pulse width modulated control signals, switched on / off for voltage conversion. Rather, the two circuit breaker and the reverse polarity switch act around switches, which are controlled by a dedicated protection unit of the DC-DC converter or an external protection device and usually only in case of failure in the DC-DC converter, such. B. in the case of an electrical short circuit, an overvoltage, an overcurrent or a reverse polarity, are turned off according to the determined type of interference and thus separate corresponding electrical connections from the DC-DC converter to external circuit components.

By the term "only" is meant that the DC-DC converter in each case only a single primary-side circuit breaker in said primary-side converter current path and / or only a single secondary-side disconnector in the secondary-side converter current path. Preferably, the DC-DC converter also includes only one polarity reversal protection switch in said ground current path.

The two circuit breakers protect each of the primary side or the secondary side connected external circuit components from damage caused by the interference in the DC-DC converter, such. As electrical short circuits, surges or overcurrents. In the case of one of the above disturbances, one of the two or both disconnecting switches is opened in a controlled manner, so that the external circuit components are electrically isolated from the DC-DC converter and thus protected from being damaged by the aforementioned disturbance.

The polarity reversal protection protects both the primary side and the secondary side connected external circuit components from damage caused by the polarity reversal on or in the DC-DC converter. In the case of a reverse polarity, the single reverse-polarity protection switch is opened in a controlled manner and the DC-DC converter is disconnected from the electrical ground, so that the circuit is interrupted by the DC-DC converter.

In this case, the only polarity reversal protection switch replaces further isolating shears in the primary-side and / or secondary-side transformer current path, which are otherwise required in addition to the above-mentioned disconnectors. Without the single polarity reversal circuit breaker, for example, in each case an additional circuit breaker required, which in each case in the primary side and / or secondary side Wandlerstrompfad must be connected in pairs and anti-serial with the respective circuit breaker above to allow adequate protection against possible reverse polarity.

As a result, the only polarity reversal protection switch replaces two otherwise required disconnectors. In this case, the polarity reversal protection switch connects the converter circuit to the ground electrically in the fault-free state of the DC-DC converter. In the case of a reverse polarity, this separates the converter circuit from the ground and thus protects the DC-DC converter and the external circuit components from damage caused by the reverse polarity.

The fact that two otherwise required Trennschater have been replaced in the converter current path with a single reverse-circuit breaker in the ground current path, the DC-DC converter can be produced more cheaply.

This provides a cost-effective and at the same time safe DC-DC converter. Since the DC-DC converter comprises fewer switches, it also has comparatively low power loss and is thus energy-efficient.

For example. the polarity reversal protection switch is designed as a semiconductor switch and antiserially connected to the primary-side and / or the secondary-side disconnector, which is or are also designed as a semiconductor switch or are.

The term "antiserially connected" means that the transmission directions of two or more anti-serially connected switches, ie the current flow directions of the switches (or in their respective load current path), lie in opposite directions. If the switches are designed, for example, as a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) switch, the forward directions of these MOSFET switches are the directions of flow of the respective drain-source currents of the MOSFET switches.

The fact that the circuit breakers are connected antiserially to each other, it is sufficient for each of the Wandlerstrompfade between the converter circuit and one of the ground power connection and the primary-side or the secondary side power connection only a single circuit breaker (a reverse polarity protection switch and at least one of the two disconnectors) and thus only in total two or a maximum of three circuit breakers to protect the DC-DC converter and the external circuit components from damage by reverse polarity or other electrical interference on or in the DC-DC converter. Due to the small number of circuit breakers can thus be saved on manufacturing costs. In addition, the small number of the circuit breakers has a positive effect on power loss lines, since these few circuit breakers cause a correspondingly low power loss.

For example. The DC-DC converter comprises both the primary-side and the secondary-side disconnector. In this case, the primary-side and the secondary-side disconnector are mutually connected antiserially to the reverse polarity reversal switch.

For example. are the reverse polarity switch, the primary-side and / or the secondary-side disconnector each designed as a MOSFET switch.

For example. The DC-DC converter furthermore comprises a primary-side electromagnetic filter which is electrically connected (or its filter path) in the primary-side converter current path between the primary-side disconnecting switch and the converter circuit. Alternatively or in addition to the primary-side filter comprises the DC-DC converter, for example. A secondary-side electromagnetic filter (or its filter section) is electrically connected in the secondary-side converter current path between the converter circuit and the secondary-side disconnector.

For example. are the primary-side and / or the secondary-side filter negative voltage output side (ie via their respective ground terminal) electrically connected directly to the ground power connection.

For example. the primary-side and / or the secondary-side filter negative voltage output side (ie via their respective ground terminal) are electrically connected directly to an electrical connection point, wherein the connection point is in the ground current path between the converter circuit and the reverse polarity protection switch. This prevents that caused by a capacitor in the filter electrical short circuit can not bypass the reverse-circuit breaker, or that the reverse polarity reverser switch in the case of caused by a capacitor in the filter electrical short circuit by controlled opening the DC-DC converter and the external circuit components connected to damage can protect the short circuit.

For example. The DC-DC converter further comprises a primary-side current meter for measuring a primary-side current of the DC-DC converter. In this case, the primary-side current meter is electrically connected in the primary-side converter current path between the primary-side disconnecting switch and the primary-side filter. Alternatively or in addition to the primary-side current meter, the DC-DC converter comprises, for example, a secondary-side current meter for measuring a secondary-side current of the DC-DC converter. In this case, the secondary-side current meter is electrically connected in the secondary-side converter current path between the converter circuit and the secondary-side filter.

By using in each case a single circuit breaker, in particular in the form of a MOSFET switch in each case, in the primary-side or in the secondary-side converter current path, the maximum switchover power loss occurring across the possible operating points of the DC-DC converter is reduced. In addition, there is a more homogeneous power loss distribution over all possible operating points of the DC-DC converter. In addition, the manufacturing cost of the DC-DC converter can be reduced.

According to a further aspect of the invention, a (multi-voltage) vehicle electrical system, in particular a motor vehicle, especially a hybrid electric / electric vehicle, is provided.

The electrical system comprises a first electrical system branch with a first vehicle electrical system voltage and a second vehicle electrical system branch with a second vehicle electrical system voltage.

The electrical system further comprises a DC-DC converter described above, which is electrically connected to the first electrical system branch via the primary-side power connection and to the second electrical system branch via the secondary-side electrical connection.

For example. are the first vehicle electrical system voltage at about 48 volts and / or the second electrical system voltage at about 12 volts.

Advantageous embodiments of the DC-DC converter described above are, as far as the rest, transferable to the above-mentioned electrical system, to be regarded as advantageous embodiments of the electrical system.

Description of the drawing:

In the following, an exemplary embodiment of the invention with reference to the accompanying drawings is explained in more detail. The single figure shows a schematic representation of a vehicle electrical system BN an electric vehicle with a DC-DC converter GW according to an embodiment of the invention.

The electrical system BN comprises a first electrical system branch BZ1 with a first vehicle electrical system voltage U1 of 48 volts and a second board branch BZ2 with a second vehicle electrical system voltage U2 from 12 volts.

The electrical system BN further comprises the DC-DC converter GW , which is between the two electrical system branches BZ1 . BZ2 is arranged and set up, the first vehicle electrical system voltage U1 in the second vehicle electrical system voltage U2 and / or vice versa.

The DC-DC converter GW includes a primary-side power connection SA1 and is on this at the first electrical system branch BZ1 or at its positive current path and thus at the first vehicle electrical system voltage U1 electrically connected.

The DC-DC converter GW further includes a secondary side power connection SA2 and is on this at the second electrical system branch BZ2 or at its positive current path and thus at the second vehicle electrical system voltage U2 electrically connected.

The DC-DC converter GW also includes a ground power connection MA and is above this on an electrical ground GND or at the vehicle mass KL31 electrically connected to the electric vehicle.

The two electrical systems branches BZ1 . BZ2 are negative voltage side also with the electrical ground GND and thus with the ground power connection MA of the DC-DC converter GW electrically connected.

The DC-DC converter GW further comprises a converter circuit WS for converting between the first and the second vehicle electrical system voltage U1 . U2 , whose converter stage between the primary side and the secondary side power connection SA1 . SA2 electrically connected.

In this embodiment, the converter circuit comprises WS as the converter stage, a half-bridge HB with two switches connected in series with each other K1 and K2 , which with their respective load current paths in a current path between the primary-side power connection SA1 and the ground power connection MA are electrically connected. Here are the two switches K1 and K2 designed as a MOSFET switch.

The converter circuit WS further includes a coil L which is in a current path between the center tap MG the half bridge HB and the secondary side power connector SA2 electrically connected.

The DC-DC converter GW also includes a primary side disconnect switch K1 in the form of a MOSFET switch, which with its load current path in a primary-side converter current path WP1 between the primary-side power connection SA1 and the converter circuit WS or the positive voltage side switch K1 the half bridge HB the converter circuit WS electrically connected.

The DC-DC converter GW further comprises a primary-side ammunition meter SM1 known type, such. B. in the form of a Hall sensor, and a primary-side electromagnetic filter FT1 known type. Here are the primary-side ammunition SM1 and the primary-side filter FT1 in the primary-side converter current path WP1 between the primary-side disconnector K1 and the converter circuit WS and the positive voltage side switch K1 electrically connected in series.

On the secondary side includes the DC-DC converter GW analogous to a secondary-side disconnector K2 in the form of a MOSFET switch, which with its load current path in a secondary-side converter current path WP2 between the coil L the converter circuit WS and the secondary side power connector SA2 electrically connected.

Here are the primary-side and the secondary-side disconnector K1 . K2 connected antiserially to each other.

The DC-DC converter GW further comprises a secondary-side ammeter SM2 the known type, such. B. in the form of a Hall sensor, and a secondary-side electromagnetic filter FT2 the known type. Here are the secondary-side ammunition SM2 and the secondary-side filter FT2 secondary-side transformer current path WP2 between the coil L of the converter circuit WS and the secondary side disconnector K2 electrically connected.

The DC-DC converter GW further includes a reverse voltage protection switch K5 in the form of a MOSFET switch connected to its load current path in a ground current path MP between the negative voltage side switch K1 the half bridge HB the converter circuit WS and the ground power connection MA electrically connected.

In this case, the reverse polarity protection switch K5 antiserial to the primary-side and the secondary-side disconnector K1 . K2 connected.

The primary-side disconnector is used here K1 to protect the first electrical system branch BZ1 from damage due to electrical interference in the DC-DC converter GW , such as As electrical short circuits, overvoltages or overcurrents, which disturbances or even defects in the first electrical system branch BZ1 being able to lead. For this purpose, the circuit breaker K1 in the case of a fault detected in the DC-DC converter in a manner known to those skilled in the art GW controlled open in a manner known to those skilled in the art, whereby the electrical connection from the DC-DC converter GW to the first electrical system branch BZ1 is disconnected and thus the first electrical system branch BZ1 is protected.

The secondary-side disconnector K2 serves ananlog for the protection of the second electrical system branch BZ2 from damage caused by the mentioned electrical disturbances in the DC-DC converter GW , which cause disturbances or even defects in the second electrical system branch BZ2 being able to lead. For this purpose, the circuit breaker K2 in the case of the detected fault in the DC-DC converter GW controlled open, eliminating the electrical connection from the DC-DC converter GW to the second electrical system branch BZ2 is disconnected and thus the second electrical system branch BZ2 is protected.

The polarity reversal protection switch K5 serves to protect the two electrical system branches BZ1 . BZ2 against reverse polarity in or on the DC-DC converter GW , In the case of reverse polarity detected in a manner known to the person skilled in the art, the polarity reversal protection switch becomes K5 controlled controlled in a manner known to those skilled in the art, whereby the circuits of the DC-DC converter GW to the two Bordnetzzweigen BZ1 . BZ2 be interrupted and thus the two electrical system branches BZ1 . BZ2 be protected against damage by reverse polarity.

In that the two circuit breakers K1 . K2 and the polarity reversal protection switch K5 connected antiserially to each other, is sufficient for each of the two transformer current paths WP1 . WP2 and the mass flow path MP in each case only a single circuit breaker K1 . K2 or. K5 , which together the DC-DC converter GW and the two electrical system branches BZ1 . BZ2 reliable protection.

This can be dispensed with further switches, which are otherwise in the two Wandlerstrompfaden WP1 . WP2 in each case serially and antiserially to the primary-side or the secondary-side disconnector K1 . K2 must be connected to the two electrical systems branches BZ1 . BZ2 from damage caused by the aforementioned interference.

Due to the small number of circuit breakers K1 . K2 and K5 can the DC-DC converter GW be produced inexpensively. In addition, the DC-DC converter has GW with the small number of circuit breakers K1 . K2 and K5 accordingly a low total power loss.

The two filters FT1 . FT2 are negative voltage side via their respective ground terminal at an electrical connection point VP in a ground current path MP between the negative voltage side switch K1 the half bridge HB the converter circuit WS and the ground power connection MA electrically connected and the reverse voltage circuit breaker K5 electrically connected.

Alternatively, the filters FT1 . FT2 negative voltage side via their respective ground connection directly to the ground power connection MA be connected.

Claims (10)

DC-DC converter (GW), comprising: - A primary-side power connection (SA1) for connecting the DC-DC converter (GW) to a first voltage (U1); - A secondary-side power connection (SA2) for connecting the DC-DC converter (GW) to a second voltage (U2); - A ground power terminal (MA) for connecting the DC-DC converter (GW) to an electrical ground (GND); a converter circuit (WS) for converting between the first (U1) and the second (U2) voltage electrically connected between the primary-side (SA1) and secondary-side (SA2) power terminals; - One, esp. Single, ground-side reverse polarity protection switch (K5), which is electrically connected in a ground current path (MP) between the converter circuit (WS) and the ground power terminal (MA); a single primary-side disconnecting switch (K1) and / or a single secondary-side disconnecting switch (K2), the single primary-side disconnecting switch (K1) being electrically connected in a primary-side transformer current path (WP1) between the primary-side power terminal (SA1) and the converter circuit (WS) , and / or the single secondary-side disconnecting switch (K2) is electrically connected in a secondary-side transformer current path (WP2) between the converter circuit (WS) and the secondary-side power terminal (SA2). DC-DC converter (GW) according to Claim 1 , wherein the reverse polarity protection switch (K5) is designed as a semiconductor switch and antiserial to the primary-side (K1) and / or the secondary-side (K2), designed as a semiconductor switch disconnector is connected. DC-DC converter (GW) according to Claim 1 or 2 comprising the primary-side (K1) and secondary-side (K2) circuit breakers, the primary-side (K1) and secondary-side (K2) circuit breakers being antiserially connected to each other and to the reverse-connection protection switch (K5). DC-DC converter (GW) according to one of the preceding claims, wherein the reverse polarity protection switch (K5), the primary-side (K1) and / or the secondary-side (K2) disconnector are each formed as a MOSFET switch. A DC-DC converter (GW) according to one of the preceding claims, further comprising: - a primary-side electromagnetic filter (FT1) electrically connected in the primary-side converter current path (WP1) between the primary-side disconnecting switch (K1) and the converter circuit (WS); and / or - a secondary-side electromagnetic filter (FT2), which in the secondary side Transducer current path (WP2) between the converter circuit (WS) and the secondary-side disconnector (K2) is electrically connected. DC-DC converter (GW) according to Claim 5 , wherein the primary-side (FT1) and / or the secondary-side (FT2) filter negative voltage output side are electrically connected directly to the ground power connection (MA). DC-DC converter (GW) according to Claim 5 in which the primary-side (FT1) and / or the secondary-side (FT2) filter are electrically connected directly to an electrical connection point (VP) on the negative voltage output side, the connection point (VP) in the ground current path (MP) between the converter circuit (WS) and the polarity reversal protection switch ( K5) is located. DC-DC converter (GW) according to one of Claims 5 to 7 further comprising: - a primary-side current meter (SM1) electrically connected in the primary-side converter current path (WP1) between the primary side cutoff switch (K1) and the primary side filter (FT1); and / or a secondary-side current meter (SM2) which is electrically connected in the secondary-side converter current path (WP2) between the converter circuit (WS) and the secondary-side filter (FT2). On-board network (BN) for a motor vehicle, comprising: - A first electrical system branch (BZ1) with a first vehicle electrical system voltage (U1); - A second electrical system branch (BZ2) with a second vehicle electrical system voltage (U2); - A DC-DC converter (GW) according to one of the preceding claims; - Wherein the DC-DC converter (GW) via the primary-side power connector (SA1) on the first electrical system branch (BZ1) and the secondary-side power connector (SA2) is electrically connected to the second electrical system branch (BZ2). Electrical system after Claim 9 , wherein the first vehicle electrical system voltage (U1) is about 48 volts, and / or the second vehicle electrical system voltage (U1) is about 12 volts.

Images