JP5389221B2 - Vehicle power supply - Google Patents

Description

  The present invention relates to a vehicle power supply device mounted on an electric vehicle or the like.

  Considering environmental problems, vehicles equipped with high voltage batteries and high output motors such as electric vehicles and hybrid vehicles are attracting attention. Such a vehicle has a voltage converter for converting the power of the high voltage battery and supplying it to the second battery, or for converting the power generated by the high output motor and supplying it to the high voltage battery. It is installed. In recent years, synchronous rectification type voltage converters have been widely used for the purpose of improving the conversion efficiency of the voltage converter.

  As a conventional vehicle power supply device using a synchronous rectification type voltage converter, for example, a vehicle power supply device as shown in FIG. 6 is known. FIG. 6 shows only the main part, and the control circuit and the like are omitted. In the first voltage converter 31 constituting the power supply device, a first battery 32 is connected as an input power source on the primary side, and a second battery 33 and an electric load 34 are connected on the secondary side. . The first battery 32 is turned on and off by the main switch 35. A high voltage is applied from the first battery 32 to the input capacitor 36 and the positive and negative input terminals of the inverter circuit unit 37, converted into alternating current by the inverter circuit unit 37, stepped down by the transformer 38, and rectified by the rectifier circuit unit 39. The smoothed DC voltage is smoothed by the smoothing circuit unit 40 and then supplied to the second battery 33 (see, for example, Patent Document 1).

In the case of the circuit as shown in FIG. 6, when the first voltage converter 31 is operating when the main switch 35 is turned off, the input voltage is reduced. Since the output voltage is lower than the voltage of the second battery 33, the current flows backward from the second battery 33 to the first voltage converter 31. This is a phenomenon peculiar to the voltage converter of the synchronous rectification type. If the synchronous rectification is stopped, the backflow phenomenon does not occur even if the output voltage of the first voltage converter 31 is lower than the voltage of the second battery 33.
Depending on the magnitude of the reverse current, the switching element of the first voltage converter 31 may be destroyed, which is dangerous. In order to avoid this, the voltage converter of the synchronous rectification method is provided with a safety function (not shown) that detects the low load state just before the current flows backward and stops the synchronous rectification before the current flows backward. It has been.

  If the electrical load 34 is small when the main switch 35 is switched from on to off, the safety function works, and the occurrence of backflow can be prevented. However, when the electrical load 34 is large, the input voltage of the first voltage converter 31 sharply decreases and the time until the current flows backward is short, so the response of the safety function for stopping the synchronous rectification is not in time, There is a risk that backflow cannot be prevented. In order not to reduce the input voltage of the first voltage converter 31 sharply, it is necessary to increase the capacitance of the input capacitor 36 to change the input voltage gently.

7 includes a second voltage converter 42 for driving the motor 41 in parallel with the first voltage converter 31 of the circuit of FIG. 6, for example, a power supply device mounted on a hybrid vehicle or the like. FIG. The second voltage converter 42 is composed of an inverter circuit unit 44 composed of an input capacitor 43 and a bridge circuit of a switching element. The second voltage converter 42 converts the DC voltage of the first battery 32 into a three-phase AC and supplies it to the motor 41. It comes to supply. In the present circuit, the first voltage converter 31 is always connected in parallel with the second voltage converter 42, so that the capacitance of the input capacitor 36 of the first voltage converter 31 is the second voltage converter 42. Therefore, the capacitance of the input capacitor 43 increases. Since the capacity of the input capacitor 43 of the second voltage converter 42 is sufficiently larger than the capacity of the input capacitor 36 of the first voltage converter 31, the risk of backflow described above can be reduced in the circuit of this configuration.
Regarding the technology for sharing capacitors with a plurality of voltage converters, for example, in a power conversion system in which a plurality of voltage source inverters are connected to a common DC power supply, a common smoothing capacitor is used as a smoothing means for the DC power supply. A technique is disclosed (for example, see Patent Document 2).

JP 2002-171751 A (3rd page, FIG. 1) JP-A-7-143757 (page 3, FIG. 1)

  In the power supply device having the circuit configuration as shown in FIG. 7, since the capacitor is shared, as described above, when the main switch is turned from on to off, current flows from the second battery to the first voltage converter. Backflow can be suppressed. However, in the vehicle power supply device, the terminal screw may be loosened due to vehicle vibration or the like. For example, if the connection between the first voltage converter 31 and the second voltage converter 42 is cut off, the input capacitor of the first voltage converter 31 is shown in FIG. Since the capacitance is only the input capacitor 36, there is a problem that when the electrical load 34 is large, the change in the input voltage becomes steep and the above-described backflow phenomenon may not be prevented.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a highly reliable vehicle power supply device that prevents backflow from the second battery to the first voltage converter. To do.

  A power supply device for a vehicle according to the present invention includes a first battery that supplies power to a high-voltage load mounted on the vehicle, a second battery that supplies power to auxiliary devices mounted on the vehicle, and an output side A second battery is connected to the first voltage converter for stepping down the voltage of the first battery and supplying it to the second battery, and a high voltage load is connected to the output side, and the voltage of the first battery Is converted to a voltage suitable for a high voltage load, and a smoothing circuit connected to the input side of both voltage converters and supplied with power from the first battery. An input capacitor of one voltage converter; an input capacitor of a second voltage converter; and two connection conductors connected to the positive and negative electrodes of both input capacitors, each connection conductor having a first voltage Connected to the terminal connected to the converter and to the second voltage converter. And the terminal that, and a terminal connected to the first battery in which are integrally formed by a single conductive member.

According to the vehicle power supply device of the present invention, the two connection conductors connected to the positive electrode and the negative electrode of the input capacitor of the smoothing circuit connected to the input side of the first voltage converter and the second voltage converter. Each has a terminal connected to the first voltage converter, a terminal connected to the second voltage converter, and a terminal connected to the first battery, and is integrated by a single conductive member. When the main switch of the first battery is switched from on to off, even if the connection between the second voltage converter and the smoothing circuit is disconnected, the first voltage converter becomes a smoothing circuit. Since the input voltage of the first voltage converter decreases due to the action of both input capacitors, the synchronous rectification is stopped before the backflow phenomenon occurs to the first voltage converter. Safety can be ensured. Therefore, a highly reliable vehicle power supply device can be provided.
Also, since the connection conductor of the smoothing circuit is formed integrally with the connection portion with the input capacitor and each terminal portion connected to the outside, the number of connection points is reduced, and the reliability of connection with each component device is improved. improves.

It is a circuit diagram which shows the principal part of the vehicle power supply device by Embodiment 1 of this invention. It is a perspective view which shows an example of the smoothing circuit part of the vehicle power supply device in Embodiment 1 of this invention. It is a perspective view which shows the other example of the smoothing circuit part of the power supply device for vehicles in Embodiment 1 of this invention. It is a perspective view which shows another example of the smoothing circuit part of the vehicle power supply device in Embodiment 1 of this invention. It is a perspective view which shows another example of the smoothing circuit part of the power supply device for vehicles in Embodiment 1 of this invention. It is a circuit diagram which shows the principal part of the conventional vehicle power supply device. FIG. 7 is a circuit diagram in which a second voltage converter is added to the circuit of FIG. 6.

Embodiment 1 FIG.
1 is a circuit diagram showing a main part of a vehicle power supply apparatus according to Embodiment 1 of the present invention. In the figure, a DC-DC converter 4 (hereinafter referred to as a first voltage converter) is connected to a smoothing circuit 3 to which a high voltage first battery 1 as an input power source and a main switch 2 for turning on and off the first battery 1 are connected. Simply referred to as a converter 4) and an inverter 5 as a second voltage converter are connected in parallel. Note that the control circuit and the like are omitted.
A low-voltage second battery 6 is connected to the output side of the converter 4, and the second battery 6 is connected to low-voltage (for example, 12 V) electricity such as auxiliary equipment mounted on the vehicle. A load 7 is connected to supply power to them. A high voltage load mounted on the vehicle is connected to the output side of the inverter 5. As an example of the high voltage load, FIG. 1 shows a case of a three-phase motor 8 that drives a vehicle.

In the smoothing circuit 3, a converter input capacitor 9 for suppressing the oscillation of the converter 4 and an inverter input capacitor 10 for suppressing the oscillation of the inverter 5 are incorporated in parallel, and the positive electrode of the first battery 1 is connected to both terminals thereof. The negative electrode is connected.
The converter 4 includes an inverter circuit unit in which four switching elements 11 are bridge-connected, a step-down transformer 12 that steps down the output voltage, and a pair of secondary coils that are connected in the same direction to the secondary side of the step-down transformer 12. And a smoothing circuit unit composed of two rectifying elements 13 for full-wave rectification, and a smoothing circuit unit composed of a choke coil 14 and a smoothing capacitor 15.
One inverter 5 includes a three-phase bridge circuit including six switching elements 16, converts the direct current of the first battery 1 into a three-phase alternating current, and supplies the three-phase alternating current to the motor 8 that is a high voltage load. .
In FIG. 1, the switching elements mounted on the converter 4 and the inverter 5 are IGBTs or MOSFETs. However, the switching elements are not limited to these and may be configured with other switching functions. Further, although the converter 5 is an insulating type, it may be a non-insulating type.

FIG. 2 is a perspective view showing one structure of the smoothing circuit 3 of FIG. As shown in the figure, the smoothing circuit 3 includes a converter input capacitor 9, an inverter input capacitor 10, and two connection conductors 17 made of thin conductive flat conductors (bus bars) connecting the input capacitors 9, 10. , 18.
Both connection conductors 17, 18 are arranged on the side surfaces of both input capacitors 9, 10, and in the middle of the longitudinal direction of each connection conductor 17, 18, a capacitor connection portion connected to a terminal of each input capacitor 9, 10. 17a and 18a are provided integrally. The capacitor connecting portion 17a is connected to one terminal of both input capacitors 9 and 10, and the capacitor connecting portion 18a is connected to the other terminal of both input capacitors 9 and 10. In addition, illustration of the terminal of each capacitor | condenser is abbreviate | omitted.

In addition, intermediate connection terminals 17b and 18b that are branched and led out in a direction orthogonal to the longitudinal direction are provided at intermediate portions in the longitudinal direction of the connection conductors 17 and 18, respectively.
Further, the end portions of the connection conductors 17 and 18 on the converter input capacitor 9 side in the longitudinal direction are connection terminals 17c and 18c connected to the converter 4, and the other end on the inverter input capacitor 10 side is provided. The parts are connection terminals 17 d and 18 d connected to the inverter 5. As shown in the drawing, each of the connection conductors 17 and 18 is integrally formed of a single conductive member including each terminal portion. That is, there is no connection portion that connects the connection conductors in the middle of the connection conductor.

2 is compared with the circuit diagram of FIG. 1, the connection terminals 17c and 18c of the connection conductors 17 and 18 of FIG. 2 are the terminals on the input side of the converter 4 in the connection portions 19 and 20 of FIG. 2 are connected to the terminals on the input side of the inverter 5 in the connection portions 21 and 22 of FIG. 1, and the intermediate connection terminals 17b and 18b of FIG. 1 and a main circuit 2 are connected in series.
Note that the input capacitors 9 and 10 constituting the smoothing circuit 3 are shown as being composed of film capacitors in FIG. 2, but the present invention is not limited to this. For example, other types of capacitors such as electrolytic capacitors may be used. You may comprise with a capacitor | condenser.
In addition, the two connection conductors 17 and 18 on the positive electrode side and the negative electrode side are arranged in parallel in the drawing, but the present invention is not limited to this. Furthermore, although both the capacitors 9 and 10 are shown adjacently arranged, the present invention is not limited to this, and it is only necessary that they are connected via the same connection conductor.

The operation of the vehicle power supply device configured as described above will be briefly described with reference to FIG.
First, the case where the motor 8 is driven will be described. The direct current of the first battery 1 charged to a high voltage is input to the inverter 5 through the smoothing circuit 3, converted into a three-phase alternating current by the bridge circuit of the switching element 16 of the inverter 5, and then sent to the motor 8. As a result, the motor 8 is driven.
On the other hand, the second battery 6 supplies power to the electric load 7 connected to the circuit. Here, when power is supplied from the first battery 1 to the second battery 6, power is supplied from the first battery 1 to the converter 4 via the smoothing circuit 3, and the AC is exchanged by the bridge circuit of the switching element 11 of the converter 4. After being converted, stepped down by the step-down transformer 12, rectified by the rectifying element 13 of the rectifying circuit unit, smoothed by the choke coil 14 and the smoothing capacitor 15 of the smoothing circuit unit, and then fed to the second battery 6 and charged. . Since the operations of the inverter 5 and the converter 4 are known techniques, detailed description thereof is omitted.

In the above operation, when the main switch 2 is switched from on to off and the converter 4 as the first voltage converter is operating, the input voltage of the converter 4 decreases and the output voltage of the converter 4 decreases to the second voltage. Therefore, the current flows backward from the second battery 6 to the converter 4. For this reason, although not shown in the figure, a safety function is provided that detects a low load state just before the current flows backward and stops synchronous rectification before the current flows backward.
Also, a safety function is provided that immediately stops synchronous rectification even when the converter input capacitor 9 is disconnected.

Next, the operation of the smoothing circuit 3 of the present embodiment will be described.
As described with reference to FIG. 2, both input capacitors 9 and 10 of the smoothing circuit 3 are connected to the flat connecting conductor 1
Since the connection is fixed integrally at 7 and 18, sufficient connection strength can be secured.
As described above, if the main switch 2 is turned from on to off while the converter 4 is operating, a reverse flow phenomenon occurs. However, since both input capacitors 9 and 10 of the smoothing circuit 3 are connected in parallel, the capacitor Since the capacity increases, the speed at which the input voltage decreases becomes slow, and it is possible to operate the safety function before stopping the reverse flow to the converter 4 to stop the synchronous rectification. Therefore, safety can be ensured. .

Here, if it is assumed that the connection is disconnected at the connection portions 21 and 22 (see FIG. 1) between the inverter 5 and the smoothing circuit 3, the connection portions 19 and 20 between the converter 4 and the smoothing circuit 3 are assumed even in this case. Since the capacitors 9 and 10 act in the same manner as described above when the main switch 2 is switched from on to off, the backflow phenomenon is suppressed and safety can be ensured.
Further, when the connection portions 19 and 20 between the converter 4 and the smoothing circuit 3 are disconnected, it is detected by a safety function (not shown) that the converter input capacitor 9 has been disconnected, and the synchronous rectification is immediately stopped. , Can prevent backflow.
Further, since the connection conductors 17 and 18 of the smoothing circuit 3 are integrally formed including a connection portion with both capacitors and a connection terminal with the outside, the reliability of connection with each component device is improved. Can do.

Next, another configuration example of the smoothing circuit will be described.
FIG. 3 is a perspective view showing another configuration example of the smoothing circuit 3. Components equivalent to those in FIG. 2 are denoted by the same reference numerals and description thereof is omitted. In this embodiment, a plurality of converter input capacitors 9 and a plurality of inverter input capacitors 10 are provided. In the figure, each of them is composed of two capacitors 9a, 9b and 10a, 10b. Thus, even if there are a plurality of cases, they can be configured compactly if they are arranged as shown in the figure. The connection conductors 17 and 18 can be accommodated only by changing the lengths of the capacitor connection portions 17a and 18a.

FIG. 4 is a perspective view showing another configuration example of the smoothing circuit 3. Although it is almost the same as FIG. 2, in the case of FIG. 2, the capacitor connecting portions 17 a and 18 a of the connection conductors 17 and 18 have slits for individual connection to the capacitors 9 and 10. However, in the case of FIG. 4, the connecting portions of the capacitors 9 and 10 are integrally formed without providing a slit.
When both the input capacitors 9 and 10 are arranged adjacent to each other, it is easier to process and assemble if they are integrated as shown in FIG.

FIG. 5 is a perspective view showing still another configuration example of the smoothing circuit 3. For example, in the smoothing circuit 3 configured as shown in FIG. 2 described above, both the capacitors 9 and 10 and the conductor main body excluding the connection terminals to the outside of the connection conductors 17 and 18 are made of a mold insulator such as a resin. 23 is molded and integrated.
With such a configuration, when incorporated in a vehicle as a power supply device for a vehicle, it is possible to reliably prevent the connection portion with the capacitor from being loosened due to vibration during use, and reliability is improved.
Needless to say, the present invention can also be applied to the configuration shown in FIGS.

  In the above description, although both the input capacitors 9 and 10 of the smoothing circuit 3 were demonstrated as an individual thing, you may comprise both capacitors together with one input capacitor. In that case, the configuration is further simplified, the number of connection points is reduced, and the reliability is further improved.

  Moreover, in FIG. 1, although the motor 8 which drives vehicles, such as an electric vehicle, was demonstrated as an example as a high voltage load connected to the inverter 5 which is a 2nd voltage converter, it changes to this. An in-vehicle charger or an electric compressor may be used.

As described above, according to the vehicle power supply device of the first embodiment, power is supplied to the first battery that supplies power to the high-voltage load mounted on the vehicle and the auxiliary devices mounted on the vehicle. The second battery is connected to the second battery on the output side, the first voltage converter that steps down the voltage of the first battery and supplies it to the second battery, and the high voltage load is connected to the output side A second voltage converter that converts the voltage of the first battery into a voltage suitable for a high voltage load, and a smoothing circuit that is connected to the input side of both voltage converters and is supplied with power from the first battery, The smoothing circuit includes an input capacitor of the first voltage converter, an input capacitor of the second voltage converter, and two connection conductors connected to the positive electrode and the negative electrode of both input capacitors, The connection conductor includes a terminal connected to the first voltage converter, and a second Since it has a terminal connected to the voltage converter and a terminal connected to the first battery and is integrally formed by a single conductive member, it has excellent connection strength with the input capacitor, When the main switch of the first battery is turned from on to off, even if the connection between the second voltage converter and the smoothing circuit is disconnected, the first voltage converter and the smoothing circuit are connected. Thus, the speed at which the input voltage of the first voltage converter is reduced becomes slow, and the synchronous rectification is stopped before the backflow phenomenon occurs in the first voltage converter, thereby ensuring safety.
Also, since the connection conductor of the smoothing circuit is formed integrally with the connection portion with the input capacitor and each terminal portion connected to the outside, the number of connection points is reduced, and the reliability of connection with each component device is improved. improves.
Even when the terminals of the first voltage converter and the smoothing circuit are disconnected, the function of stopping the synchronous rectification works immediately to prevent backflow.

  In addition, in the case where the input capacitor of the first voltage converter and the input capacitor of the second voltage converter of the smoothing circuit are configured by one input capacitor, the configuration is simplified and the number of connection points is reduced. Compared with this, reliability is further improved.

In addition, since the conductor main body excluding the portion of each terminal of the connection conductor and both input capacitors are integrally formed by molding with a mold insulator, the connection portion with the capacitor against vibration etc. when incorporated in a vehicle Can be prevented and the reliability is improved.
it can.

DESCRIPTION OF SYMBOLS 1 1st battery 2 Main switch 3 Smoothing circuit 4 Converter (1st voltage converter)
5 Inverter (second voltage converter) 6 Second battery 7 Electric load 8 Motor (high voltage load)
DESCRIPTION OF SYMBOLS 9 Input capacitor for converters 10 Input capacitor for inverters 11 Switching element 12 Step-down transformer 13 Rectifier element 14 Choke coil 15 Smoothing capacitor 16 Switching element 17, 18 Connection conductor 17a, 18a Capacitor connection part 17b, 18b Intermediate connection terminal 17c, 17d, 18c , 18d Connection terminal 19, 20, 21, 22 Connection portion 23 Mold insulator.

Claims (3)

A first battery that supplies power to a high-voltage load mounted on the vehicle, a second battery that supplies power to auxiliary devices mounted on the vehicle, and the second battery connected to the output side A first voltage converter for stepping down the voltage of the first battery and supplying the voltage to the second battery; and the high voltage load is connected to the output side, and the voltage of the first battery is changed to the high voltage A second voltage converter for converting to a voltage suitable for a load, and a smoothing circuit connected to the input side of the two voltage converters and powered by the first battery,
The smoothing circuit has an input capacitor of the first voltage converter, an input capacitor of the second voltage converter, and two connection conductors connected to a positive electrode and a negative electrode of the input capacitors.
Each of the connection conductors has a terminal connected to the first voltage converter, a terminal connected to the second voltage converter, and a terminal connected to the first battery. A power supply device for a vehicle, which is integrally formed of one conductive member. The vehicle power supply device according to claim 1,
A power supply device for a vehicle, wherein the input capacitor of the first voltage converter and the input capacitor of the second voltage converter of the smoothing circuit are constituted by one input capacitor. In the vehicle power supply device according to claim 1 or 2,
A power supply device for a vehicle, wherein a conductor main body portion excluding a portion of each terminal of the connection conductor and the two input capacitors are integrally formed by molding with a mold insulator.

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