JP2015146690A - Power supply unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an electrical shock during maintenance by rapidly discharging a Y capacitor.SOLUTION: In the power supply unit, a series circuit of a first and a second Y capacitors is connected in parallel to a smoothing capacitor on a load circuit side from a contactor. In this case, between the load circuit side of the contactor and a ground node, there is provided a Y capacitor discharge circuit formed to have a series circuit of a discharge switch and a discharge resistance. In discharging the smoothing capacitor, the discharge switch is turned on, thereby executing discharge of the first and the second Y capacitors.

Description

  The present invention relates to a technical field of a power supply device that supplies power from a battery to a load circuit.

JP 2012-65503 A JP 2006-42459 A JP2013-92396A JP 2008-58085 A

For example, in each of the above-mentioned patent documents, a technique regarding a power supply device that supplies power from a battery to a load circuit in an electric vehicle, a hybrid vehicle, or the like is described.
Patent Document 1 discloses a technique for discharging the remaining energy of a capacitor by supplying power stored in a smoothing capacitor provided between a battery and a motor to another device. Patent Document 2 discloses a technique for discharging a smoothing capacitor when an inverter casing of a power converter is opened.
Patent Documents 3 and 4 describe circuit configurations for detecting battery leakage.

  A capacitor included in a high-voltage device mounted on a hybrid vehicle or an electric vehicle has a risk of electric shock if it is accidentally contacted with a high-voltage circuit when the housing of the high-voltage device is opened during maintenance. This capacitor is roughly classified into an X capacitor and a Y capacitor. Generally, a capacitor connected between the positive and negative power supply lines is called an X capacitor (Across the Line Capacitor), and a capacitor connected between the power supply line and the chassis ground is called a Y capacitor (Line Bypass Capacitor). The smoothing capacitor whose discharge method is described in Patent Documents 1 and 2 is an X capacitor.

Now consider the discharge of the Y capacitor. There is a possibility that electric charge remains in the Y capacitor even after the discharge of the X capacitor is completed. If electrification remains in the Y capacitor, the operator may get an electric shock during maintenance.
Accordingly, an object of the present invention is to provide a power supply device that quickly discharges not only the X capacitor but also the Y capacitor when the power supply from the battery to the load circuit is stopped.

1stly, the power supply device which concerns on this invention is the positive electrode side contactor which connects / disconnects the positive electrode side of a battery and the positive electrode side of a load circuit, The negative electrode side contactor which connects / disconnects the negative electrode side of the said battery, and the negative electrode side of the said load circuit, A smoothing capacitor connected between the positive electrode side and the negative electrode side of the load circuit, and a first Y capacitor and a second capacitor connected in parallel with the smoothing capacitor in a state where they are connected in series with a ground node as a connection point Y capacitor, a smoothing capacitor discharge circuit connected in parallel with the smoothing capacitor, at least one of the load circuit side of the positive contactor and the load circuit side of the negative contactor, and between the ground node, And a Y capacitor discharge circuit formed to have a series circuit of a discharge switch and a discharge resistor.
Even when the smoothing capacitor (X capacitor) is discharged by the smoothing capacitor discharge circuit, electric charge may remain in the Y capacitor. The discharge of the Y capacitor is performed by the Y capacitor discharge circuit. If a discharge circuit is provided for at least one of the first and second Y capacitors and the potential is set to the ground node potential, the other Y capacitor is also discharged.

Second, in the power supply device according to the present invention described above, as the Y capacitor discharge circuit, the first Y capacitor discharge circuit formed between the load circuit side of the positive contactor and the ground node, and the negative electrode It is desirable to include a second Y capacitor discharge circuit formed between the load circuit side of the side contactor and the ground node.
That is, a discharge circuit is formed corresponding to each of the first and second Y capacitors.

Thirdly, in the power supply device according to the present invention, when the power supply from the battery to the load circuit is stopped, the first contactor and the negative contactor are turned off before the first contact. It is desirable to provide a control unit for controlling each discharge switch in the second Y capacitor discharge circuit to be on.
Prior to turning off the contactor, the first and second Y capacitor discharge circuits function so that the voltage dividing states of the first and second Y capacitors are set by the discharge resistors in the first and second Y capacitor discharge circuits. It will be ready. By equalizing the voltages at both ends of the first and second Y capacitors, the discharge is performed with the same time constant as that of the smoothing capacitor when the contactor is turned off.

Fourthly, in the power supply device according to the present invention described above, a series circuit of a first leakage detection switch and a first detection resistor is provided between the high voltage side connection point of the battery and the ground node, A leakage detecting circuit formed so as to have a series circuit of a second leakage detection switch and a second detection resistor between the low-voltage side connection point of the battery and the ground node; and all of the first detection resistors Alternatively, it is desirable that one or both of a part and one part or both of all or part of the second detection resistor also serve as all or part of the discharge resistor of the Y capacitor discharge circuit.
Thus, a part of the leakage detection circuit can be used to form the Y capacitor discharge circuit with a small number of additional parts.
Fifth, it is preferable that the power supply device according to the present invention further includes a voltage detection unit that detects a voltage across the detection resistor that also serves as a discharge resistor of the Y capacitor discharge circuit.
In this case, the voltage detector performs voltage detection for detecting leakage, and the voltage detector can detect the discharge state of the Y capacitor.

  According to the present invention, when power supply from the battery to the load circuit is stopped, not only the X capacitor but also the Y capacitor can be discharged quickly. This can prevent an electric shock during maintenance.

It is explanatory drawing of the power supply device structure of the comparative example of the process leading to this invention. It is explanatory drawing of the voltage change of the Y capacitor at the time of X capacitor discharge. It is explanatory drawing of the power supply device structure of the 1st Embodiment of this invention. It is explanatory drawing of the discharge operation of 1st Embodiment. It is a flowchart of the control processing for the discharge operation of 2nd Embodiment. It is explanatory drawing of the power supply device structure of 2nd Embodiment. It is explanatory drawing of the discharge operation of 2nd Embodiment. It is a flowchart of the control processing for the discharge operation of 2nd Embodiment.

  Embodiments of the present invention will be described below. However, in order to understand the embodiment, the configuration of the power supply apparatus (comparative example) in the process leading to the present invention will be described with reference to FIGS. 1 and 2, and then the first and second embodiments of the present invention in which FIG. 1 is further improved will be described. A power supply device as an embodiment will be described with reference to FIG.

<1. Power supply configuration assumed in the process leading to the present invention>
The power supply device described in FIG. 1 and FIGS. 3 and 6 described later is a power supply device mounted on, for example, an electric vehicle, a hybrid vehicle, or the like, and is a power supply device that supplies power from the battery 1 to the load circuit side. Although not shown in each of FIGS. 1, 3, and 6, the terminals 15 and 16 in the positive and negative power lines on the load circuit side are, for example, inverters for supplying driving power to the motor of the vehicle, A DC / DC converter that generates a power supply voltage for each electrical system is connected.

In FIG. 1, the positive electrode of the battery 1 is connected to the positive terminal 15 side of the load circuit via a positive contactor SWp configured by, for example, a relay. Further, the negative electrode of the battery 1 is connected to the terminal 16 side of the load circuit via a negative contactor SWn constituted by, for example, a relay.
Both contactors SWp and SWn are turned on in response to, for example, an ignition operation, thereby starting power supply from the battery 1 to the load circuit side. Further, both contactors SWp and SWn are turned off in response to an ignition off operation or vehicle collision detection, and the power supply from the battery 1 is stopped.

On the load circuit side of both contactors SWp and SWn, a smoothing capacitor (X capacitor) Cx is connected between the positive and negative power supply lines.
A discharge resistor Rd is connected in parallel with the smoothing capacitor Cx. In this example, the discharge resistor Rd is always connected to the smoothing capacitor Cx. However, a switch may be provided in series with the discharge resistor Rd so that it is normally disconnected from the smoothing capacitor Cx.
A first Y capacitor Cp is connected between the positive power line and the chassis ground potential (ground node GN), and a second Y capacitor Cn is connected between the negative power line and the ground node GN. The two Y capacitors Cp and Cn constitute a series circuit and are connected in parallel with the smoothing capacitor Cx.

  A precharge switch SWpre and a precharge resistor Rpre are connected in parallel with the contactor SWp. The smoothing capacitor Cx is charged when the contactor SWp is turned on, but it is not preferable to apply a high voltage with the charge almost empty. Therefore, it is preferable to perform precharge immediately before the contactor SWp is turned on. For this purpose, the precharge switch SWpre is turned on so that the smoothing capacitor Cx can be preliminarily charged while the current is limited by the precharge resistor Rpre.

FIG. 1 shows an example in which a leakage detection circuit 10 is provided on the battery 1 side. In the leakage detection circuit 10, for example, a leakage detection switch SW1 and detection resistors R1p and R2p are connected in series between the high voltage side connection point Na of the battery 1 and the ground node GN. In addition, a leakage detection switch SW2 and detection resistors R1n and R2n are connected in series between the low voltage side connection point Nb of the battery 1 and the ground node GN. The positions of the high-pressure side connection point Na and the low-pressure side connection point Nb are not limited to the illustrated positions. For example, the positive electrode terminal and the negative electrode terminal of the entire battery 1 may be used as the high voltage side connection point Na and the low voltage side connection point Nb.
In addition, a voltage detection unit 11 is provided to detect, for example, a voltage Vrp across the detection resistor R2p and a voltage Vrn across the detection resistor R2n.
In the power supply device of FIG. 1, the high voltage point by the battery 1 is electrically insulated from the chassis ground. When performing leakage detection, the voltage detection unit 11 detects the voltage Vrp across the detection resistor R2p with the leakage detection switch SW1 turned on, and the voltage detection unit 11 with the leakage detection switch SW2 turned on. A voltage Vrn across the detection resistor R2n is detected. The insulation resistance is calculated from the detection voltages Vrp and Vrn. The leakage detection switches SW1 and SW2 may be turned on simultaneously. For example, the control unit 12 can detect a leakage situation by performing a predetermined calculation using the voltage detection result of the voltage detection unit 11 and determining the insulation resistance.

  The control unit 12 performs processing for detecting leakage, processing related to the notification, and on / off control of each switch of the power supply device. A switch control signal SG is output for on / off control. For example, the contactors SWp and SWn are on / off controlled by the switch control signals SGp and SGn. The precharge switch SWpre is turned on / off by the switch control signal SGpre. Further, the leakage control switches SW1 and SW2 are turned on / off by the switch control circuits SG1 and SG2 in order to detect leakage.

The resistor Rp is shown as a plus side insulation resistance on the load circuit side (high voltage device side).
The resistor Rn is shown as a minus side insulation resistance on the load circuit side (high voltage device side).
The resistor Rpb is shown as a plus-side insulation resistance inside the battery 1.
The resistor Rnb is shown as a negative side insulation resistance inside the battery 1.

In such a power supply device, voltage changes of the Y capacitors Cp and Cn when the smoothing capacitor Cx is discharged will be described with reference to FIG.
In FIG. 2, the vertical axis represents voltage and the horizontal axis represents time. The voltage V1 is the voltage Vcx of the smoothing capacitor Cx when the contactors SWp and SWn are on. In this case, since the smoothing capacitor Cx is charged to a voltage equal to the voltage of the battery 1, the voltage V1 = the battery voltage.
The voltage Vcp of the Y capacitor Cp and the voltage Vcn of the Y capacitor Cn are voltages obtained by dividing the voltage Vcx by the insulation resistances Rp and Rn. Therefore, it is determined by the ratio of the insulation resistances Rp and Rn. In the example of FIG. 2, Vcp is not equal to Vcn when the voltage balance of the Y capacitors Cp and Cn is lost, and the voltage Vcp = V2 and the voltage Vcn = V3. V2 + V3 = V1.
In the case of the configuration shown in FIG. 1, when the contactors SWp and SWn are turned on, the voltages Vcp and Vcn of the Y capacitors Cp and Cn are affected by the leakage detection circuit 10, but the leakage detection switches SW1 and SW2 are turned on. Therefore, it can be considered that the period is determined by the ratio of the insulation resistances Rp and Rn.

Here, it is assumed that the contactors SWp and SWn are turned off at time t0. From this point of time, discharge of the smoothing capacitor Cx using the discharge resistor Rd as a discharge path is started, and the voltage Vcx of the smoothing capacitor Cx decreases toward 0 V with a predetermined time constant as indicated by a solid line.
Along with this, the voltages Vcp and Vcn of the Y capacitors Cp and Cn also decrease as indicated by the dashed line and the alternate long and short dash line, but the voltage balance of the Y capacitors Cp and Cn before the start of discharge is broken as shown in the figure. The voltages Vcp and Vcn when the discharge of the smoothing capacitor Cx is completed do not become 0V, but become the voltage Vcp = V2 ′ and the voltage Vcn = V3 ′. | V2 ′ | = | V3 ′ |.
The voltages Vcp, Vcn of the Y capacitors Cp, Cn remaining in this way are then slowly discharged over time by the insulation resistances Rp, Rn, which generally have a value of several MΩ or more.

When the contactors SWp and SWn are turned off, the voltage state of the Y capacitors Cp and Cn becomes like this. For example, immediately after turning off the ignition at the time of maintenance or inspection of the automobile, the electric charge of the Y capacitors Cp and Cn It can happen that the operator is electrocuted.
Therefore, in the present embodiment to be described later, discharge circuits for Y capacitors Cp and Cn are provided in the configuration of FIG. 1 so that the Y capacitors Cp and Cn are appropriately discharged. In addition, this can be realized only by adding a very simple configuration.

<2. First Embodiment>
FIG. 3 shows the configuration of the power supply device according to the first embodiment. Note that the same parts as those in FIG.
The configuration of FIG. 3 is obtained by adding a discharge switch SW3 and a discharge resistor R3p to the configuration of FIG. One end of the discharge resistor R3p is connected to the load circuit side terminal of the plus side contactor SWp, and the other end is connected to one end of the discharge switch SW3. The other end of the discharge switch SW3 is connected to the connection point of the detection resistors R1p and R2p. The discharge switch SW3 is on / off controlled by a switch control process SG3 from the control unit 12.

  In this case, the discharge resistor R3p, the discharge switch SW3, and the detection resistor R2p form the discharge circuit 20 of the Y capacitors Cp and Cn. That is, when the contactors SWp and SWn are off, the precharge switch SWpre is off, and the leakage detection switches SW1 and SW2 are off, the switch SW3 is turned on so that the discharge resistor R3p and the detection resistor R2p are connected to the Y capacitor Cp. A discharge path is formed.

With this configuration, it is possible to quickly discharge the Y capacitors Cp and Cn as shown in FIG. FIG. 4 shows the state after the discharge of the smoothing capacitor Cx in FIG. 2 is completed. That is, the voltage Vcp of the Y capacitor Cp = V2 ′ and the voltage Vcn of the Y capacitor Cn = V3 ′. Here, when the discharge switch SW3 is turned on at time t1, the discharge path of the Y capacitor Cp is formed, and the voltage Vcp of the Y capacitor Cp decreases toward 0 V as shown by the broken line. Since the discharge of the smoothing capacitor Cx is completed, | Vcp | = | Vcn | and Vcp + Vcn = 0V. Accordingly, the Y capacitor Cn is also discharged. Specifically, the Y capacitor Cn is discharged through the path of the smoothing capacitor Cx, the discharge resistor R3p, and the detection resistor R2p, and the voltage Vcn also goes to 0V.
Eventually, by turning on the discharge switch SW3 for a certain period as shown in FIG. 4, the voltage Vcp = Vcn = 0V and the discharge is completed. Then, the discharge switch SW3 may be turned off at time t2 after the discharge is completed.

For the above operation, the control unit 12 performs the process of FIG. As an emergency response such as ignition off or collision, the control unit 12 proceeds from step S101 to S102 when the power supply to the load circuit is stopped, and first confirms that the leakage detection switches SW1 and SW2 are off. As described above, the leakage detection switches SW1 and SW2 for detecting leakage are not necessarily turned on at this time, but for the operation of the discharge circuit 20, the leakage detection switches SW1 and SW2 are turned off. It is necessary to be. Therefore, off control is performed by the switch control signals SG1 and SG2 (or the off state is continued).
In step S103, the control unit 12 turns off the contactors SWp and SWn by the switch control processes SGp and SGn. As a result, discharging of the smoothing capacitor Cx is started as shown in FIG. 2 (time point t0). In this state, the control unit 12 waits for a predetermined time as step S104. The predetermined time may be slightly longer than the time when the smoothing capacitor Cx is expected to be completely discharged from the time constant of the smoothing capacitor Cx and the discharge resistance Rd.

When the discharge of the smoothing capacitor Cx is completed, the voltages of the Y capacitors Cp and Cn are not necessarily 0V as described above, and it is assumed that charges remain as the voltages V2 ′ and V3 ′. Therefore, after waiting for a predetermined time, the control unit 12 turns on the discharge switch SW3 by the switch control signal SG3 in step S105. As a result, the Y capacitors Cp and Cn are discharged as after time t1 in FIG.
The controller 12 waits for completion of discharge in step S106, and then turns off the discharge switch SW3 in step S107.
The determination of the completion of the discharge in step S106 may be made on the condition that a predetermined time set in consideration of the discharge time assumed from the discharge time constant is used. In addition, it has been described that the detection resistor R2p can detect the voltage Vrp by the voltage detection unit 11 for detecting leakage, but this detection resistor R2p is also used as a part of the discharge resistor. Then, the discharge state can be monitored by detecting the voltage Vrp of the detection resistor R2p. Therefore, the control unit 12 may monitor the voltage Vrp detected by the voltage detection unit 11 and determine the completion of discharge as step S106.

<3. Second Embodiment>
FIG. 6 shows the configuration of the power supply device according to the second embodiment. Note that the same parts as those in FIG.
The configuration of FIG. 6 is obtained by adding a discharge switch SW4 and a discharge resistor R4n to the configuration of FIG. One end of the discharge resistor R4n is connected to the load circuit side terminal of the minus side contactor SWn, and the other end is connected to one end of the discharge switch SW4. The other end of the discharge switch SW4 is connected to the connection point of the detection resistors R1n and R2n. The discharge switch SW4 is on / off controlled by a switch control process SG4 from the control unit 12.

  In this case, in addition to the discharge circuit 20 described in the first embodiment, the discharge resistor R4n, the discharge switch SW4, and the detection resistor R2n form the discharge circuit 30 of the Y capacitor Cn. That is, when the contactors SWp and SWn are turned off, the precharge switch SWpre is turned off, and the leakage detection switches SW1 and SW2 are turned off, the switches SW3 and SW4 are turned on, so that the discharge resistor R3p and the detection resistor R2p become the Y capacitor. The discharge path of Cp is formed, and the discharge resistance R4n and the detection resistance R2n form the discharge path of the Y capacitor Cn.

Also in this configuration, the Y capacitors Cp and Cn can be discharged quickly as shown in FIG. For example, by performing the control sequence described in FIG. 5 (however, in step S105, both the discharge switches SW3 and SW4 are turned on), the discharge of the Y capacitors Cp and Cn can be quickly performed as in the first embodiment. It can be carried out. In that case, the residual charge of the Y capacitor Cp is discharged through the discharge circuit 20, and the charge of the Y capacitor Cn is discharged through the discharge circuit 30.
However, in the case of the second embodiment, a discharge operation as described in FIGS. 7 and 8 below can also be performed.

As shown in FIG. 7, the discharge switches SW3 and SW4 are turned on at time t10 prior to time t11 when the contactors SWp and SWn are turned off.
Before time t10, the voltage Vcx = V1, the voltage Vcp = V2, and the voltage Vcn = V3 of the smoothing capacitor Cx are set as in the case before time t0 in FIG. V2 + V3 = V1.
When the discharge switches SW3 and SW4 are turned on in this state, the voltage Vcp = Vcn = V4 can be obtained as shown by the broken line and the alternate long and short dash line in FIG. V4 = V1 / 2 As described above, the voltages Vcp and Vcn of the Y capacitors Cp and Cn have voltage values obtained by dividing the resistances of the insulation resistors Rp and Rn. However, when the discharge switches SW3 and SW4 are turned on when the contactors SWp and SWn are on, the voltages Vcp and Vcn of the Y capacitors Cp and Cn are (discharge resistance R3p + detection resistance R2p) and (discharge resistance R4n + detection resistance R2n). ).

Of course, this is based on the premise that (discharge resistance R3p + detection resistance R2p) is sufficiently small with respect to insulation resistance Rp, and (discharge resistance R4n + detection resistance R2n) is sufficiently small with respect to insulation resistance Rn.
Further, in order to set the voltage Vcp = Vcn, it is necessary that (discharge resistance R3p + detection resistance R2p) = (discharge resistance R4n + detection resistance R2n).
By designing the circuit so as to satisfy these conditions, it is possible to balance the voltages of the Y capacitors Cp and Cn by turning on the discharge switches SW3 and SW4 at time t10.

Then, when the contactors SWp and SWn are subsequently turned off at time t11, the discharge of the smoothing capacitor Cx is started, but the Y capacitors Cp and Cn can also be discharged with the same time constant as the smoothing capacitor Cx. Then, after the discharge of the Y capacitors Cp and Cn is completed, the discharge switches SW3 and SW4 may be turned off.
In this case, the discharge of the Y capacitors Cp and Cn is considered to be performed via the discharge resistor Rd.

For the above operation, the control unit 12 performs the process of FIG. In response to an emergency such as an ignition off or a collision, the control unit 12 proceeds from step S201 to S202 when the power supply to the load circuit is stopped. First, the leakage detection switches SW1 and SW2 are turned off (or continued off). To do.
In step S203, the control unit 12 turns on the discharge switches SW3 and SW4 by the switch control signals SG3 and SG4. As a result, the voltage balance of the Y capacitors Cp and Cn is achieved as shown after time t10 in FIG.
It waits until voltage balance is taken in step S204. The determination in step S204 may be based on the elapse of a predetermined time set in consideration of the expected time until the voltages Vcp and Vcn match, or the voltage may be actually detected. That is, the control unit 12 may monitor the voltages Vrp and Vrn detected by the voltage detection unit 11 to determine voltage matching.

When the voltage balance is achieved, in step S205, the control unit 12 turns off the contactors SWp and SWn by the switch control processes SGp and SGn. As a result, the discharge of the smoothing capacitor Cx and the discharge of the Y capacitors Cp and Cn are started as shown as the time t11 in FIG. In this state, the control unit 12 waits for a predetermined time as step S206. The predetermined time may be slightly longer than the time when the smoothing capacitor Cx is expected to be completely discharged from the time constant of the smoothing capacitor Cx and the discharge resistance Rd. Alternatively, in this case as well, the control unit 12 may monitor the voltages Vrp and Vrn detected by the voltage detection unit 11 to determine the completion of discharge.
In step S207, the control unit 12 turns off the discharge switches SW3 and SW4.

<4. Effects and Modifications of Embodiment>
According to the above first and second embodiments, the following effects can be obtained.
The power supply apparatus according to the embodiment includes a positive contactor SWp that connects and disconnects the positive electrode side of the battery 1 and the positive electrode side of the load circuit, a negative contactor SWn that connects and disconnects the negative electrode side of the battery 1 and the negative electrode side of the load circuit, and a load circuit The smoothing capacitor Cx connected between the positive electrode side and the negative electrode side of the first Y capacitor Cp and the second Y capacitor Cp connected in parallel with the smoothing capacitor Cx in a state where they are connected in series with the ground node as a connection point. A Y capacitor Cn, a discharge resistor Rd (smoothing capacitor discharge circuit) connected in parallel with the smoothing capacitor Cx, and a Y capacitor discharge circuit (discharge circuit 20, or discharge circuits 20 and 30) are included.
Discharge circuit 20 is formed to have a series circuit of discharge switch SW3 and discharge resistors (R3p, R2p) between plus side contactor SWp and ground node GN. Discharge circuit 30 is composed of minus side contactor SWn and ground node. It is formed so as to have a series circuit of a discharge switch SW4 and discharge resistors (R4p, R2n) between GN.

By providing at least the discharge circuit 20 as in the first embodiment, when the smoothing capacitor Cx is discharged, that is, when the contactors SWp and SWn are turned off, the Y capacitors Cp and Cn are also reliably within a predetermined time. It is possible to discharge quickly. Accordingly, it is possible to prevent a situation in which the operator is in an electric shock during maintenance.
Also, by providing the first and second discharge circuits 20 and 30 as in the second embodiment, the Y capacitors Cp and Cn can be reliably and quickly discharged.
Note that a configuration example in which only the discharge circuit 30 is provided without the discharge circuit 20 is also considered as a modified example, and in that case as well, the Y capacitors Cp and Cn can be reliably and quickly discharged.

  Further, as described in the control sequence of the second embodiment, when the control unit 12 stops the power supply from the battery 1 to the load circuit, the discharge is performed before the timing when the contactors SWp and SWn are turned off. The discharge switches SW3 and SW4 in the circuits 20 and 30 can be controlled to be turned on. In this case, the voltage dividing state of the Y capacitors Cp and Cn can be set by the discharge resistors (R3p + R2p) (R4p + R2n) in the discharge circuits 20 and 30. Accordingly, when the voltages at both ends of the Y capacitors Cp and Cn are equalized and then the contactors SWp and SWn are turned off, the Y capacitors Cp and Cn can be discharged with the same time constant as the smoothing capacitor. Thereby, quicker discharge becomes possible.

The above embodiment is an example in which the leakage detection circuit 10 is provided. Further, by connecting a part of the leakage detection circuit 10 to the load circuit side of the contactors SWp and SWn, the discharge circuits 20 and 30 can be realized with a very small number of additional elements.
Specifically, in the first embodiment, part of the detection resistance (R2p) of the leakage detection circuit 10 also serves as part of the discharge resistance of the discharge circuit 20. In the second embodiment, a part (R2n) of the detection resistance of the leakage detection circuit 10 also serves as a part of the discharge resistance of the discharge circuit 30. Thereby, a discharge path can be easily formed using the existing leakage detection circuit 10.
A configuration in which all of the positive side detection resistors (R1p and R2p) of the leakage detection circuit 10 also serve as a part of the discharge resistance of the discharge circuit 20 is conceivable. For example, there is a configuration in which the terminal of the discharge switch SW3 is connected to the connection point between the leakage detection switch SW1 and the detection resistor R1p. Similarly, a configuration in which all of the negative side detection resistors (R1n and R2n) of the leakage detection circuit 10 also serve as a part of the discharge resistance of the discharge circuit 30 is conceivable. For example, the terminal of the discharge switch SW4 is connected to the connection point between the leakage detection switch SW2 and the detection resistor R1n.
Furthermore, a configuration example in which the discharge resistor R3p (or R4n) is not provided and the discharge resistor of the discharge circuit 20 (or 30) is formed only by the detection resistor R2p (or R2n) is also conceivable.

In addition, by using the detection resistor R2p (R2n) as a discharge resistor, it is possible to detect a voltage during discharge using the voltage detection unit 11 for detecting leakage. Thereby, the control part 12 can confirm completion of discharge.
Furthermore, since the voltage can be detected, the control unit 12 determines that there is a residual voltage in the Y capacitors Cp and Cn, for example, when the discharge circuit 20 (30) does not complete the discharge even if it functions for a predetermined time. A warning can be given to maintenance personnel. For example, warning display on a vehicle display, warning sound output, or the like may be performed. As a result, electric shock can be prevented even when discharge is not performed properly for some reason.

Although the embodiment and the modified examples have been described above, various modified examples of the present invention can be considered.
A power supply device that does not include the leakage detection circuit 10 is also assumed. In that case, for example, the discharge circuit 20 may be formed such that a series circuit of the discharge R3p and the discharge switch SW3 is connected to the ground node GN.
Further, although the embodiment assumes a power supply device for a vehicle such as an electric vehicle or a hybrid vehicle, the present invention can be widely applied to power supply devices other than those for vehicles.

  DESCRIPTION OF SYMBOLS 1 ... Battery, 10 ... Electric leakage detection circuit, 11 ... Voltage detection part, 12 ... Control part, 20, 30 ... Discharge circuit, Cx ... Smoothing capacitor, Cp, Cn ... Y capacitor, SWp ... Positive side contactor, SWn ... Negative side Contactor, SW3, SW4 ... discharge switch, R3p, R4n ... discharge resistance, R2p, R2n ... detection resistance

Claims (5)

A positive contactor for connecting and disconnecting the positive side of the battery and the positive side of the load circuit;
A negative contactor for connecting and disconnecting the negative electrode side of the battery and the negative electrode side of the load circuit;
A smoothing capacitor connected between a positive electrode side and a negative electrode side of the load circuit;
A first Y capacitor and a second Y capacitor connected in parallel with the smoothing capacitor in a state of being connected in series to each other with a ground node as a connection point;
A smoothing capacitor discharge circuit connected in parallel with the smoothing capacitor;
A Y capacitor discharge circuit formed to have a series circuit of a discharge switch and a discharge resistor between at least one of the load circuit side of the positive contactor and the load circuit side of the negative contactor and the ground node. And a power supply unit. As the Y capacitor discharge circuit,
A first Y capacitor discharge circuit formed between the load circuit side of the positive contactor and the ground node;
The power supply device according to claim 1, further comprising: a second Y capacitor discharge circuit formed between a load circuit side of the negative contactor and the ground node. When stopping the power supply from the battery to the load circuit, the discharge switches in the first and second Y capacitor discharge circuits are turned on before the timing when the positive contactor and the negative contactor are turned off. With a control unit to control
The power supply device according to claim 2. A series circuit of a first leakage detection switch and a first detection resistor between the high voltage side connection point of the battery and the ground node; and a second circuit between the low voltage side connection point of the battery and the ground node. A leakage detection circuit formed to have a series circuit of a leakage detection switch and a second detection resistor;
The whole or part of the first detection resistor and one or both of the whole or part of the second detection resistor also serve as all or part of the discharge resistance of the Y capacitor discharge circuit. The power supply device according to claim 3. The power supply device according to claim 4, further comprising a voltage detection unit that detects a voltage across the detection resistor that also serves as a discharge resistor of the Y capacitor discharge circuit.

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