JP7177005B2 - Power supply system and its control method - Google Patents

Description

The present invention relates to a power supply system mounted on an electric vehicle and a control method thereof.

2. Description of the Related Art In recent years, electric vehicles such as electric transportation equipment having a drive motor as a power generation source and electric vehicles such as hybrid vehicles having a drive motor and an internal combustion engine as power generation sources have been actively developed. In such an electric vehicle, an electric load including a drive motor and a battery are connected via a main contactor.

Further, in order to drive an electric load with power supplied from a battery, it is necessary to precharge a smoothing capacitor included in the electric load in advance. However, if the main contactor is turned on while the smoothing capacitor is not charged, an excessive rush current is generated from the battery side to the electrical load, and the contactor may weld. For this reason, the power supply system mounted on the electric vehicle turns on the precharge contactor connected in parallel with the main contactor to start the connection between the DC power supply and the electric load. The main contactor is turned on after the smoothing capacitor is precharged (see, for example, Patent Document 1).

JP 2015-80332 A

As described above, in the conventional power supply system, the main contactor is turned on after precharging of the smoothing capacitor is completed. , an inrush current of a magnitude corresponding to the potential difference between the voltage across the smoothing capacitor and the voltage across the DC power supply at that time flows. In addition, in recent years, the performance of batteries has improved, and the internal resistance tends to decrease, so the rush current that flows at the moment the main contactor is turned on tends to increase. Therefore, if the main contactor is repeatedly turned on and off and an inrush current exceeds the permissible number of times according to the performance of the main contactor, the main contactor may be welded.

In order to solve this problem, it is conceivable to use a voltage sensor with high detection accuracy so that the main contactor can be turned on at an appropriate timing so that a large inrush current does not flow. cost may increase.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power supply system for an electric vehicle that can prevent welding of a main contactor without using a highly accurate voltage sensor, and a control method thereof.

(1) A control method according to the present invention is a control method for a power supply system (for example, a power supply system 1 to be described later) mounted on an electric vehicle (for example, a vehicle V to be described later), wherein the power supply system includes a DC power supply (For example, a positive electrode power line (for example, a primary A positive electrode main contactor (for example, a positive electrode main contactor 51 to be described later) and a positive electrode precharge contactor (for example, a positive electrode precharge contactor 52 to be described later) provided in parallel with each other on the side positive power line 21); A negative electrode main contactor (for example, a negative electrode main contactor 61 described later) and a negative electrode precharge contactor (for example, a and a negative precharge contactor 62), and the control method closes the positive and negative precharge contactors and starts precharging the smoothing capacitor when starting to connect the DC power supply and the electrical load. (for example, S11 and S12 in FIG. 3 and S31 and S32 in FIG. 5, which will be described later), and a step of closing one of the positive and negative main contactors after the precharging (for example, a step of closing one of the positive and negative main contactors) (for example, S15 in FIG. 3 and S35 in FIG. 5) and a step of closing the other main contactor after closing the one main contactor (for example, S18 in FIG. 3 and S38 in FIG. 5 described later), The order in which the positive and negative main contactors are closed may be changed according to predetermined conditions.

(2) In this case, the DC power supply is a storage battery, and the activation mode of the electric vehicle includes an external charging mode in which the storage battery can be charged with electric power supplied from an external power supply source, and a discharge mode from the storage battery. The order of closing the positive and negative main contactors is changed depending on whether the activation mode is the external charging mode or the vehicle running mode. preferably.

(3) In this case, the power supply system includes an inlet to which a plug of the external power supply source is connected, and whether or not the startup mode is the external charging mode is determined by connecting the plug to the inlet. It is preferable to judge by whether or not there is.

(4) In this case, it is preferable that the order of closing the positive and negative main contactors is the reverse order of the previous connection between the DC power supply and the electrical load.

(5) In this case, after closing the one main contactor, it is preferable to close the other main contactor after the voltage value across the smoothing capacitor becomes equal to or less than a predetermined threshold value.

(6) In this case, the control method includes a welding determination step (for example, a welding determination process in FIG. 6 to be described later) for determining whether or not the positive and negative electrode main contactors are welded. When it is determined that any one of them is welded, it is preferable to close the main contactor that is not welded after the voltage value across the smoothing capacitor becomes equal to or less than the threshold after the precharging is completed.

(7) In this case, the welding determination step includes a step of opening the positive and negative main contactors (for example, S52 in FIG. 6, which will be described later), and a voltage difference between both ends of the smoothing capacitor before and after opening the positive and negative main contactors. a step of determining whether or not the value has decreased (for example, S54 in FIG. 6 described later); is welded (for example, S55 in FIG. 6 to be described later), and after it is determined that the voltage value across the smoothing capacitor has decreased, either one of the positive electrode and the negative electrode precharge contactor A step of closing the pole precharge contactor (for example, S56 in FIG. 6 described later) and a step of determining whether the voltage value across the smoothing capacitor has increased before and after closing the one pole precharge contactor. (for example, S58 in FIG. 6 to be described later); and a step of determining that the main contactor of the other pole is welded when it is determined that the voltage value across the smoothing capacitor has increased (for example, a step to determine S59 in FIG. 6) and after it is determined that the voltage value across the smoothing capacitor has not increased, the step of opening the precharge contactor of the one pole and closing the precharge contactor of the other pole (for example, S60 and S61 in FIG. 6 to be described later) and a step of determining whether or not the voltage value across the smoothing capacitor has increased before and after closing the precharge contactor of the other pole (for example, S63 in FIG. 6 to be described later). ), and a step of determining that the main contactor of one pole is welded when it is determined that the voltage value across the smoothing capacitor has increased (for example, S64 in FIG. 6 described later). preferably included.

(8) A power supply system (for example, a power supply system 1 to be described later) according to the present invention is mounted on an electric vehicle (for example, a vehicle V to be described later), and is a DC power supply (for example, a high voltage battery B to be described later). ) and an electrical load (for example, a load circuit 3 to be described later) including a smoothing capacitor (for example, a smoothing capacitor 35 to be described later). A positive electrode main contactor (for example, a positive electrode main contactor 51 described later) and a positive electrode precharge contactor (for example, a positive electrode precharge contactor 52 described later) provided, and a negative electrode power line ( For example, a negative electrode main contactor (for example, a negative electrode main contactor 61 to be described later) and a negative electrode precharge contactor (for example, a negative electrode precharge contactor 62 to be described later) provided in parallel with each other on a primary side negative electrode power line 22 (to be described later); When starting the connection between the DC power supply and the electric load, after the smoothing capacitor is precharged by closing the positive and negative precharge contactors, either one of the positive and negative main contactors is closed. and then closing the other main contactor (for example, an ECU 8 described later), wherein the control device determines the order of closing the positive and negative main contactors after the precharging is completed in accordance with a predetermined condition. It is characterized by changing accordingly.

(1) A power supply system of the present invention includes a positive main contactor and a positive precharge contactor provided on a positive power line, and a negative main contactor and a negative precharge contactor provided on a negative power line. Further, in the control method of the present invention, when starting connection between the DC power supply and the electric load, precharging of the smoothing capacitor is started by closing both the positive and negative precharge contactors, and this precharging is completed. After that, after closing one of the positive and negative main contactors, the other main contactor is closed. Here, when the positive and negative main contactors are closed in a predetermined order, the main contactor that is closed first has a voltage corresponding to the voltage difference between the DC power supply and the voltage across the smoothing capacitor at the moment it is closed. An inrush current will flow. Therefore, in the control method of the present invention, the order in which the positive and negative main contactors are closed after precharging is changed according to a predetermined condition. As a result, the number of inrush currents flowing at the moment the main contactor is closed can be distributed between the two main contactors, so there is no need to use a highly accurate voltage sensor or a main contactor with high current toughness. , the welding of these main contactors can be prevented.

(2) After the electric vehicle is started in the external charging mode in which the battery is charged with the power supplied from the external power supply source, the electric vehicle is ready to run with the power discharged from the battery. It is often activated under vehicle running mode. Therefore, in the control method of the present invention, the order of closing the positive and negative main contactors is changed depending on whether the start-up mode of the electric vehicle is the external charging mode or the vehicle running mode. As a result, the rush current flowing at the moment the main contactor is closed can be alternately passed through the positive main contactor and the negative main contactor. can be prevented.

(3) In the control method of the present invention, whether or not the activation mode is the external charging mode is determined by whether or not the plug is connected to the inlet. It can be properly determined under which boot mode it was booted.

(4) In the control method of the present invention, the order of closing the positive and negative main contactors is reversed from the previous order of connecting the DC power supply and the electric load. As a result, the main contactor that closes first after precharging is completed can be changed every time the DC power supply and the electric load are connected, so that the load on the two main contactors can be divided in half. , the welding of these main contactors can be prevented.

(5) In the control method of the present invention, after precharging is completed and either one of the positive and negative main contactors is closed, the voltage across the smoothing capacitor becomes equal to or less than a predetermined threshold value, and then the other is closed. main contactor. As a result, when one main contactor is closed and then the other main contactor is closed, the magnitude of the inrush current flowing through the other main contactor can be adjusted according to the threshold value.

(6) In the control method of the present invention, when it is determined that one of the positive electrode and negative electrode main contactors is welded, the voltage across the smoothing capacitor becomes equal to or less than the threshold after precharging. After that, close the main contactor that is not welded. As a result, when the non-welded main contactor is closed, the inrush current flowing through this main contactor can be adjusted to a magnitude corresponding to the threshold, so this non-welded main contactor will also be welded. can be prevented.

(7) In the control method of the present invention, in the welding determination step, the positive and negative main contactors are first opened, and both ends of the smoothing capacitor are checked depending on whether or not the voltage across the smoothing capacitor has decreased before and after the main contactors are opened. is welded or not. After that, in the control method of the present invention, the precharge contactor of either one of the positive and negative precharge contactors is closed, and the main contactor of the other pole is closed depending on whether or not the voltage value across the smoothing capacitor rises before and after that. is welded or not. Furthermore, after that, in the control method of the present invention, the precharge contactor of the other pole of the positive and negative precharge contactors is closed, and the main contactor of one pole is closed depending on whether or not the voltage value across the smoothing capacitor rises before and after that. Determine whether or not there is welding. This makes it possible to determine whether or not both or one of the positive and negative main contactors is welded.

(8) The power supply system of the present invention includes a positive main contactor and a positive precharge contactor provided on a positive power line, a negative main contactor and a negative precharge contactor provided on a negative power line, and connections between a DC power supply and an electric load. At the start of the control, the smoothing capacitor is precharged by closing the positive and negative precharge contactors, then either one of the positive and negative main contactors is closed, and then the other main contactor is closed. And prepare. Further, the control device changes the order of closing the positive electrode and negative electrode main contactors after precharging is completed according to predetermined conditions. As a result, the number of inrush currents flowing at the moment the main contactor is closed can be distributed between the two main contactors, so there is no need to use a highly accurate voltage sensor or a main contactor with high current toughness. , the welding of these main contactors can be prevented.

1 is a diagram showing configurations of a vehicle and an external charger equipped with a power supply system according to an embodiment of the present invention; FIG. 4 is a flowchart showing a specific procedure of battery connection control for connecting a battery, a load circuit, and an external charging circuit; 4 is a flowchart showing a specific procedure of first precharge control; It is a figure which shows an example of the time chart implement|achieved by 1st precharge control. 7 is a flowchart showing a specific procedure of second precharge control; 4 is a flow chart showing a specific procedure of welding determination processing for determining whether or not a positive electrode main contactor and a negative electrode main contactor are welded.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing the configuration of an electric vehicle V (hereinafter simply referred to as "vehicle") equipped with a power supply system 1 according to the present embodiment and an external charger C. As shown in FIG.

The vehicle V includes driving wheels W, a driving motor M connected to the driving wheels W, and a power supply system 1 that transfers electric power between the driving motor M and a high-voltage battery B that is a DC power supply, Prepare. In this embodiment, the vehicle V is described as an example in which the vehicle V is accelerated and decelerated mainly by the power generated by the drive motor M, but the present invention is not limited to this. The vehicle V may be a so-called hybrid vehicle in which a drive motor M and an engine are mounted as power generation sources. Further, in this embodiment, the case of using the high-voltage battery B as the DC power supply will be described, but the present invention is not limited to this. The present invention may use a fuel cell stack as the DC power source.

The drive motor M is connected to drive wheels W via a power transmission mechanism (not shown). Torque generated by the drive motor M by supplying three-phase AC power from the power supply system 1 to the drive motor M is transmitted to the drive wheels W via a power transmission mechanism (not shown), rotates the drive wheels W, and rotates the vehicle. Run V. When the vehicle V decelerates, the drive motor M functions as a generator to generate regenerative electric power and apply regenerative braking torque to the driving wheels W in accordance with the magnitude of the regenerative electric power. The regenerated electric power generated by the drive motor M charges the high-voltage battery B of the power supply system 1 as appropriate.

The power supply system 1 includes a high-voltage battery B as a DC power supply, a load circuit 3 configured by electrical equipment including a drive motor M, and a primary positive power line connecting the positive electrode of the high-voltage battery B and the load circuit 3. 21, a primary negative electrode power line 22 connecting the negative electrode of the high voltage battery B and the load circuit 3, a positive contactor circuit 5 provided on the primary positive power line 21, and a contactor circuit 5 provided on the primary negative power line 22. a negative contactor circuit 6, an external charging circuit 7 connected to power lines 21 and 22, and an electronic control unit 8 (hereinafter abbreviated as "ECU 8") that controls the load circuit 3 and the contactor circuits 5 and 6. And prepare.

The high-voltage battery B is a secondary battery capable of both discharging for converting chemical energy into electrical energy and charging for converting electrical energy into chemical energy. In the following, a case of using a so-called lithium ion storage battery that charges and discharges by moving lithium ions between electrodes as the high voltage battery B will be described, but the present invention is not limited to this.

A primary side voltage sensor 24 is connected to the power lines 21 and 22 on the high voltage battery B side of the contactor circuits 5 and 6 . The primary side voltage sensor 24 generates a voltage detection signal corresponding to the voltage between the electrodes of the high voltage battery B and transmits this voltage detection signal to the ECU 8 . Note that the voltage value detected by the primary voltage sensor 24 is hereinafter referred to as a primary voltage value Vb.

The positive contactor circuit 5 includes a positive main contactor 51 having both ends connected to the primary positive power line 21 and a positive precharge contactor 52 connected to the primary positive power line 21 in parallel with the positive main contactor 51 . and a positive electrode precharge resistor 53 . The positive electrode main contactor 51 and the positive electrode precharge contactor 52 are opened to disconnect the high voltage battery B from the load circuit 3 and the external charging circuit 7 when no command signal is input from the outside. It is of a normally open type in which it is closed when an input is being made to connect the high voltage battery B, the load circuit 3 and the external charging circuit 7 . These contactors 51 and 52 open and close according to command signals transmitted from the ECU 8 .

The negative contactor circuit 6 includes a negative main contactor 61 having both ends connected to the primary negative power line 22 and a negative precharge contactor 62 connected to the primary negative power line 22 in parallel with the negative main contactor 61 . and a negative electrode precharge resistor 63 . These negative electrode main contactor 61 and negative electrode precharge contactor 62 are opened in a state in which no command signal is input from the outside to disconnect the high voltage battery B from the load circuit 3 and the external charging circuit 7, so that the command signal is It is of a normally open type in which it is closed when an input is being made to connect the high voltage battery B, the load circuit 3 and the external charging circuit 7 . These contactors 61 and 62 open and close according to command signals transmitted from the ECU 8 .

The external charger C is a quick charger installed in charging stations, commercial facilities, public facilities, etc., which are facilities mainly intended for charging. The external charger C outputs DC of a predetermined charging voltage to the power supply system 1 of the vehicle V through the charging plug P. As shown in FIG.

The external charging circuit 7 includes an inlet 73 to which the charging plug P of the external charger C is connected, a positive charging power line 71 connecting the positive terminal of the inlet 73 and the primary side positive power line 21, and a negative terminal of the inlet 73. and a negative electrode charging power line 72 connecting the primary side negative electrode power line 22 with the primary side negative electrode power line 22 . These charging power lines 71 and 72 are connected between the contactor circuits 5 and 6 and the load circuit 3 among the positive power lines 21 and 22 . When a user (not shown) connects the charging plug P to the inlet 73, power is supplied from the external charger C to the power lines 21 and 22 on the primary side, whereby the high voltage battery B is charged.

Also, the inlet 73 is provided with a plug sensor (not shown). When the charging plug P is connected to the inlet 73 , the plug sensor generates a signal indicating that the charging plug P is connected and transmits the signal to the ECU 8 .

In the following, the startup mode in which the high-voltage battery B can be charged with the power supplied from the external charger C is referred to as the external charging mode, and the power discharged from the high-voltage battery B enables the vehicle to run. The activation mode is called a vehicle running mode.

The load circuit 3 includes a voltage converter 33, a power converter 34, a secondary positive power line 31 and a secondary negative power line 32 connecting the voltage converter 33 and the power converter 34, and the power converter 34. and a smoothing capacitor 35 having both ends connected to the secondary side positive power line 31 and the secondary side negative power line 32 .

The voltage converter 33 connects the power lines 21 and 22 on the primary side and the power lines 31 and 32 on the secondary side. Convert voltage. The voltage converter 33 is a DCDC converter configured by combining a reactor, a smoothing capacitor, a plurality of switching elements (eg, IGBTs), and the like. The voltage converter 33 turns on/off a plurality of switching elements in accordance with a gate drive signal generated at a predetermined timing from a gate drive circuit (not shown) of the ECU 8, so that the power lines 21 and 22 on the primary side and the power lines 22 on the secondary side The voltage is converted between the power lines 31 and 32 on the side.

The power converter 34 connects the secondary power lines 31 and 32 and the drive motor M, and converts power between the secondary power lines 31 and 32 and the drive motor M. FIG. The power converter 34 is, for example, a pulse-width-modulated PWM inverter equipped with a bridge circuit configured by bridge-connecting a plurality of switching elements (eg, IGBTs), and has a function of converting DC power and AC power. Prepare. The DC input/output side of the power converter 34 is connected to the power lines 31 and 32 on the secondary side, and the AC input/output side of the power converter 34 is connected to the U-phase, V-phase, and W-phase coils of the drive motor M. . The power converter 34 turns on/off the switching elements of each phase in accordance with a gate drive signal generated at a predetermined timing from a gate drive circuit (not shown) of the ECU 8 to generate direct current power in the power lines 31 and 32 on the secondary side. is converted into three-phase AC power and supplied to the drive motor M, and the three-phase AC power supplied from the drive motor M is converted into DC power and supplied to the power lines 31 and 32 on the secondary side.

A secondary side voltage sensor 36 is connected to the power lines 31 and 32 on the secondary side. The secondary voltage sensor 36 generates a voltage detection signal according to the voltage across the smoothing capacitor 35 and transmits this voltage detection signal to the ECU 8 . Note that the voltage value detected by the secondary voltage sensor 36 is hereinafter referred to as a secondary voltage value Vc. In addition, below, although the case where the smoothing capacitor is provided only in the power lines 31 and 32 of the secondary side is demonstrated, this invention is not limited to this. Smoothing capacitors may be provided not only on the power lines 31 and 32 on the secondary side but also on the power lines 21 and 22 on the primary side.

FIG. 2 is a flow chart showing a specific procedure of battery connection control for connecting the high-voltage battery B to the load circuit 3 and the external charging circuit 7. As shown in FIG. The battery connection control shown in FIG. executed.

In S1, the ECU 8 takes in the determination result of the welding determination process (see FIG. 6, which will be described later) for determining whether or not the two main contactors 51 and 61 are welded, and proceeds to S2.

In S2, the ECU 8 determines whether or not the negative electrode main contactor 61 is welded by using the determination result acquired in S1. If the determination result in S2 is YES and the negative electrode main contactor 61 is welded, the ECU 8 removes the high voltage battery B, the primary power line 21, 22, a second precharge control (see FIG. 5, which will be described later) is executed, and the process of FIG. 2 ends. If the determination result of S2 is NO, the ECU 8 proceeds to S3.

In S3, the ECU 8 determines whether or not the positive electrode main contactor 51 is welded by using the determination result obtained in S1. If the determination result in S3 is YES and the positive electrode main contactor 51 is welded, the ECU 8 removes the high voltage battery B, the primary power line 21, 22, a first precharge control (see FIGS. 3 and 4, which will be described later) is executed, and the process of FIG. 2 ends. If the determination result of S3 is NO, the ECU 8 proceeds to S4.

In S4, the ECU 8 determines whether or not a predetermined selection condition is satisfied. When the determination result of S4 is YES, the ECU 8 proceeds to S5 and executes the first precharge control, and when the determination result of S4 is NO, the ECU 8 proceeds to S6 and executes the second precharge control. . Here, as will be described later with reference to FIGS. 3 to 5, the order in which the positive main contactor 51 and the negative main contactor 61 are closed differs between the first precharge control and the second precharge control. Therefore, in the battery connection control of FIG. 2, the ECU 8 changes the order of closing the positive electrode main contactor 51 and the negative electrode main contactor 61 according to predetermined selection conditions.

Here, two specific examples of selection conditions will be described.
A first selection condition is that the activation mode of the vehicle is the external charging mode. In this case, the ECU 8 changes the order in which the positive electrode main contactor 51 and the negative electrode main contactor 61 are closed depending on whether the startup mode of the vehicle is the external charging mode or the vehicle running mode. The ECU 8 determines whether the start-up mode of the vehicle is the external charging mode by determining whether the charging plug is connected to the inlet based on the output signal of the plug sensor provided at the inlet 73. do.

A second selection condition is that the first precharge control was executed in the previous battery connection control. In this case, the ECU 8 reverses the order of closing the positive electrode main contactor 51 and the negative electrode main contactor 61 from the order in the previous battery connection control. That is, when the first precharge control was executed in the previous battery connection control, the second precharge control is executed in the current battery connection control, and the second precharge control is executed in the previous battery connection control. In this case, the first precharge control is executed in the current battery connection control.

FIG. 3 is a flowchart showing a specific procedure of first precharge control. It should be noted that the main contactors 51 and 61 and the precharge contactors 52 and 62 are open when starting the first precharge control.

FIG. 4 is a diagram showing an example of a time chart realized by the first precharge control. 4 shows, in order from the top to the bottom, the positive precharge contactor 52, the negative precharge contactor 62, the positive main contactor 51, the negative main contactor 61, the secondary voltage value Vc, and the precharge current flowing through the high voltage battery B. It shows the change in charge current.

First, in S11, the ECU 8 closes the positive precharge contactor 52, and proceeds to S12. In S12, the ECU 8 closes the negative precharge contactor 62 and proceeds to S13. As a result, the high-voltage battery B, the load circuit 3 and the external charging circuit 7 are connected via the precharge resistors 53 and 63, and precharging of the smoothing capacitor 35 of the load circuit 3 starts. As a result, as shown from time t0 to t1 in FIG. 4, the precharge current begins to flow, and the secondary side voltage value Vc begins to rise so as to asymptotically approach the primary side voltage value Vb.

In S13, the ECU 8 determines whether or not a predetermined precharge required time Tpc has elapsed since precharging of the smoothing capacitor 35 was started for the first time in S11 and S12. If the determination result in S13 is NO, the ECU 8 returns to S11. Also, when the determination result in S13 is YES, the ECU 8 determines that precharging of the smoothing capacitor 35 is completed, and proceeds to S14. Here, the required precharge time Tpc is determined according to the capacity of the smoothing capacitor 35, and is specifically, for example, about 0.5 seconds. When smoothing capacitors are provided in both the power lines 21 and 22 on the primary side and the power lines 31 and 32 on the secondary side as described above, the necessary precharge time Tpc is determined according to the combined capacity of these smoothing capacitors. be done.

In S14, the ECU 8 determines whether or not the positive electrode main contactor 51 is welded. The ECU 8 proceeds to S15 when the determination result of S14 is NO, and proceeds to S16 when the determination result of S14 is YES.

In S15, the ECU 8 closes the positive electrode main contactor 51 and proceeds to S16. As a result, the positive electrode of the high-voltage battery B is connected to the load circuit 3 and the external charging circuit 7 via the positive electrode main contactor 51, so that the precharge current bypasses the positive electrode precharge contactor 52 and the positive electrode precharge resistor 53. and flows through the positive main contactor 51 . Therefore, the rate of increase of the secondary side voltage value Vc increases as shown from time t1 to t2 in FIG.

In S16, the ECU 8 acquires the primary side voltage value Vb and the secondary side voltage value Vc, and proceeds to S17. In S17, the ECU 8 determines whether or not the value obtained by subtracting the secondary voltage value Vc from the primary voltage value Vb is equal to or less than a predetermined threshold value. If the determination result of S17 is NO, the process returns to S14, and if the determination result of S17 is YES, the process moves to S18.

In S18, the ECU 8 closes the negative main contactor 61 and proceeds to S19. As a result, the negative electrode of the high-voltage battery B is connected to the load circuit 3 and the external charging circuit 7 via the negative electrode main contactor 61 , so that the precharge current bypasses the negative electrode precharge contactor 62 and the negative electrode precharge resistor 63 . and flows through the negative main contactor 61 . As described above, in the first precharge control, after the positive main contactor 51 is closed, the high voltage battery B, the load circuit 3 and the external charging circuit 7 are connected to the precharge resistors 53 and 7 at the moment the negative main contactor 61 is closed. 63, the negative electrode main contactor 61 receives an inrush current corresponding to the difference between the primary side voltage value Vb and the secondary side voltage value Vc as shown at time t2 in FIG. flow.

In S19, the ECU 8 opens the positive electrode precharge contactor 52 and proceeds to S20. In S20, the ECU 8 opens the negative precharge contactor 62 and ends the first precharge control of FIG. As described above, in the first precharge control, the positive electrode main contactor 51 is closed, and then the negative electrode main contactor 61 is closed, thereby connecting the high voltage battery B, the load circuit 3 and the external charging circuit 7 .

As described above, the ECU 8 executes the first precharge control when it is determined that the positive electrode main contactor 51 is welded (see S3 in FIG. 2). After precharging the smoothing capacitor 35 (see S13), after the difference between the primary side voltage value Vb and the secondary side voltage value Vc becomes equal to or less than the threshold (see S17), the non-fused negative electrode main contactor 61 is closed (see S18).

FIG. 5 is a flow chart showing a specific procedure of the second precharge control. It should be noted that the main contactors 51 and 61 and the precharge contactors 52 and 62 are open when starting the second precharge control. In the second precharge control shown in FIG. 5, the processes of S31-S33, S36-S37, and S39-S40 are the same as those of S11-S12, S16-S17, and S19-S20 in the first precharge control shown in FIG. Since it is the same as the processing of , the explanation is omitted.

In S34, the ECU 8 determines whether or not the negative electrode main contactor 61 is welded. The ECU 8 proceeds to S35 when the determination result of S34 is NO, and proceeds to S36 when the determination result of S34 is YES.

In S35, the ECU 8 closes the negative electrode main contactor 61 and proceeds to S36. As a result, the negative electrode of the high-voltage battery B is connected to the load circuit 3 and the external charging circuit 7 via the negative electrode main contactor 61 , so that the precharge current bypasses the negative electrode precharge contactor 62 and the negative electrode precharge resistor 63 . and flows through the negative main contactor 61 .

In S38, the ECU 8 closes the positive electrode main contactor 51 and proceeds to S39. As a result, the positive electrode of the high-voltage battery B is connected to the load circuit 3 and the external charging circuit 7 via the positive electrode main contactor 51, so that the precharge current bypasses the positive electrode precharge contactor 52 and the positive electrode precharge resistor 53. and flows through the positive main contactor 51 . As described above, in the second precharge control, after the negative main contactor 61 is closed, the high voltage battery B, the load circuit 3 and the external charging circuit 7 are connected to the precharge resistors 53, 63, a rush current corresponding to the difference between the primary-side voltage value Vb and the secondary-side voltage value Vc flows through the positive main contactor 51 .

As described above, in the second precharge control, the negative electrode main contactor 61 is closed, and then the positive electrode main contactor 51 is closed, thereby connecting the high voltage battery B, the load circuit 3 and the external charging circuit 7 . As described above, the ECU 8 executes the second precharge control when it is determined that the negative electrode main contactor 61 is welded (see S2 in FIG. 2). After precharging the smoothing capacitor 35 (see S33), after the difference between the primary voltage value Vb and the secondary voltage value Vc becomes equal to or less than the threshold value (see S37), the positive electrode main contactor 51 that is not welded is closed (see S38).

FIG. 6 is a flowchart showing a specific procedure of welding determination processing for determining whether or not the positive electrode main contactor 51 and the negative electrode main contactor 61 are welded. The welding determination process shown in FIG. 6 is executed by the ECU 8 in response to a system stop command for stopping the power supply system 1 after the smoothing capacitor 35 is charged by performing the battery connection control shown in FIG. . It should be noted that the main contactors 51 and 61 are closed and the precharge contactors 52 and 62 are opened when starting this welding determination process.

In S51, the ECU 8 acquires the secondary voltage value Vc, and proceeds to S52. In S52, the ECU 8 opens the positive electrode main contactor 51 and the negative electrode main contactor 61, and proceeds to S53. In S53, the ECU 8 again obtains the secondary voltage value Vc after opening the main contactors 51 and 61, and proceeds to S54. In S54, the ECU 8 determines whether or not the secondary voltage value Vc has decreased before and after the main contactors 51 and 61 are opened. Here, when at least one of the main contactors 51 and 62 is opened as instructed, the charge accumulated in the smoothing capacitor 35 is discharged to the load circuit 3, so the secondary voltage value Vc drops. Therefore, the ECU 8 proceeds to S56 when the determination result of S54 is YES, and proceeds to S55 when the determination result of S54 is NO. In S55, the ECU 8 determines that both the positive electrode main contactor 51 and the negative electrode main contactor 61 are welded, and terminates the welding determination process of FIG.

In S56, the ECU 8 closes the positive precharge contactor 52, and proceeds to S57. In S57, the ECU 8 obtains the secondary side voltage value Vc after the positive precharge contactor 52 is closed, and proceeds to S58. In S58, the ECU 8 determines whether or not the secondary side voltage value Vc has increased before and after the positive precharge contactor 52 is closed. If only the negative electrode main contactor 61 of the positive electrode main contactor 51 and the negative electrode main contactor 61 is welded, closing the positive electrode precharge contactor 52 establishes continuity between the high voltage battery B and the load circuit 3, and the secondary side Voltage value Vc rises. Therefore, the ECU 8 proceeds to S60 when the determination result of S58 is NO, and proceeds to S59 when the determination result of S58 is YES. In S59, the ECU 8 determines that the negative electrode main contactor 61 is welded, and terminates the welding determination process of FIG.

In S60, the ECU 8 opens the positive electrode precharge contactor 52 and proceeds to S61. In S61, the ECU 8 closes the negative precharge contactor 62 and proceeds to S62. In S62, the ECU 8 acquires the secondary voltage value Vc after the negative precharge contactor 62 is closed, and proceeds to S63. In S63, the ECU 8 determines whether or not the secondary side voltage value Vc has increased before and after the negative precharge contactor 62 is closed. Here, when only the positive electrode main contactor 51 of the positive electrode main contactor 51 and the negative electrode main contactor 61 is welded, when the negative electrode precharge contactor 62 is closed, the high voltage battery B and the load circuit 3 are electrically connected, and the secondary side Voltage value Vc rises. Therefore, the ECU 8 proceeds to S65 when the determination result of S63 is NO, and proceeds to S64 when the determination result of S63 is YES. In S64, the ECU 8 determines that the positive electrode main contactor 51 is welded, and terminates the welding determination process of FIG.

In S65, the ECU 8 opens the negative electrode precharge contactor 62 and proceeds to S66. In S66, the ECU 8 determines that both the positive electrode main contactor 51 and the negative electrode main contactor 61 are normal, and terminates the welding determination process of FIG.

According to the power supply system 1 and its control method according to the present embodiment, the following effects are obtained.
(1) In the present embodiment, when starting connection between the high voltage battery B and the load circuit 3, precharging of the smoothing capacitor 35 is started by closing both the precharge contactors 52 and 62, and After this precharge is completed, one of the main contactors 51 and 61 is closed, and then the other main contactor is closed. In this embodiment, the order in which the main contactors 51 and 61 are closed after precharging is changed according to a predetermined condition. As a result, the number of inrush currents flowing at the moment the main contactor is closed later can be distributed between the two main contactors 51 and 61, so that a highly accurate voltage sensor can be used, and the main contactor 51 with high current toughness can be used. , 61, the welding of these main contactors 51, 61 can be prevented.

(2) In the present embodiment, the order of closing the main contactors 51 and 61 is changed depending on whether the startup mode of the vehicle V is the external charging mode or the vehicle running mode. As a result, the rush current that flows at the moment the main contactor is closed later can be alternately caused to flow through the positive electrode main contactor 51 and the negative electrode main contactor 61, so that the load on each of the main contactors 51 and 61 can be reduced. It is possible to prevent these main contactors 51 and 61 from welding.

(3) In the present embodiment, whether or not the activation mode is the external charging mode is determined by whether or not the charging plug P is connected to the inlet 73, thereby determining whether the activation mode is the external charging mode or not. It is possible to appropriately determine whether the vehicle is in the driving mode.

(4) In the present embodiment, the order of closing the main contactors 51 and 61 is reversed from the previous order when the high-voltage battery B and the load circuit 3 were connected. As a result, the main contactor to be closed first can be changed each time the high-voltage battery B and the load circuit 3 are connected after precharging is completed, so that the load on the two main contactors 51 and 61 can be substantially reduced. Since it can be divided into two halves, it is possible to prevent these main contactors 51 and 61 from being welded together.

(5) In the present embodiment, after precharging is completed and one of the main contactors 51 and 61 is closed, the difference between the primary side voltage value Vb and the secondary side voltage value Vc becomes a predetermined value. is below the threshold of the other main contactor. As a result, when one main contactor is closed and then the other main contactor is closed, the magnitude of the inrush current flowing through the other main contactor can be adjusted according to the threshold value.

(6) In the present embodiment, when it is determined that one of the main contactors 51 and 61 is welded, the primary side voltage value Vb and the secondary side voltage value Vc after the difference is below the threshold, the unwelded main contactor is closed. As a result, when the non-welded main contactor is closed, the inrush current flowing through the main contactor can be adjusted to a magnitude corresponding to the threshold value, so that the non-welded main contactor is also welded. can prevent

(7) In the present embodiment, in the welding determination process, the main contactors 51 and 61 are first opened, and the main contactors 51 and 61 are determined depending on whether or not the secondary voltage value Vc has decreased before and after the main contactors 51 and 61 are opened. It is determined whether or not both 51 and 61 are welded. After that, in this embodiment, the precharge contactor of either one of the precharge contactors 52 and 62 is closed, and the main contactor of the other pole is welded depending on whether or not the secondary voltage Vc rises before and after that. determine whether or not After that, in the present embodiment, the precharge contactor of the other pole of the precharge contactors 52 and 62 is closed, and depending on whether or not the secondary voltage value Vc rises before and after that, the main contactor of one pole is welded. determine whether or not This makes it possible to determine whether or not both or one of the main contactors 51 and 61 is welded.

As mentioned above, although one Embodiment of this invention was described, this invention is not limited to this. Detailed configurations may be changed as appropriate within the scope of the present invention.

V... vehicle (electric vehicle)
M... drive motor (electric load)
1... Power supply system B... High voltage battery (DC power supply, capacitor)
21... Primary side positive power line (positive power line)
22... Primary side negative power line (negative power line)
3 ... load circuit (electrical load)
33... Voltage converter 34... Power converter 35... Smoothing capacitor (capacitor)
5 Positive electrode contactor circuit 51 Positive electrode main contactor 52 Positive electrode precharge contactor 6 Negative electrode contactor circuit 61 Negative electrode main contactor 62 Negative electrode precharge contactor 7 External charging circuit 8 ECU (control device)

Claims (8)

A control method for a power supply system mounted on an electric vehicle, comprising:
The power system is
a positive electrode main contactor provided on a positive electrode power line connecting a positive electrode of a DC power supply and an electrical load including a smoothing capacitor;
a positive precharge contactor and a positive precharge resistor connected to the positive power line in parallel with the positive main contactor;
a negative electrode main contactor provided on a negative electrode power line that connects the negative electrode of the DC power supply and the electrical load;
a negative precharge contactor and a negative precharge resistor connected to the negative power line in parallel with the negative main contactor ;
The control method is
closing the positive and negative precharge contactors to start precharging the smoothing capacitor when starting to connect the DC power supply to the electrical load;
a step of closing either one of the positive and negative main contactors after the precharging is completed;
closing the other main contactor after closing the one main contactor;
A method of controlling a power supply system, wherein the order of closing the positive and negative main contactors is changed according to a predetermined condition. The DC power supply is a capacitor,
The startup modes of the electric vehicle include an external charging mode in which the battery can be charged with power supplied from an external power supply source, and a vehicle running mode in which the battery can run with power discharged from the battery. , divided into
2. The power system control method according to claim 1, wherein the order of closing the positive and negative main contactors is changed depending on whether the start mode is the external charging mode or the vehicle running mode. The power system comprises an inlet to which the plug of the external power supply is connected,
3. The method of controlling a power supply system according to claim 2, wherein whether or not said startup mode is said external charging mode is determined based on whether or not said plug is connected to said inlet. 2. The control method of a power supply system according to claim 1, wherein the order of closing the positive and negative main contactors is the reverse order of the previous connection between the DC power supply and the electrical load. 5. The method according to any one of claims 1 to 4, wherein after the one main contactor is closed, the other main contactor is closed after the voltage across the smoothing capacitor has become equal to or less than a predetermined threshold value. How to control the power system. a welding determination step for determining whether or not the positive and negative electrode main contactors are welded;
When it is determined that one of the positive electrode and negative electrode main contactors is welded, the welding is not performed after the voltage value across the smoothing capacitor becomes equal to or lower than the threshold value after the precharging is completed. 6. The method of claim 5, wherein the main contactor is closed. The welding determination step includes:
opening the positive and negative main contactors;
determining whether the voltage across the smoothing capacitor has decreased before and after the positive and negative main contactors are opened;
determining that both the positive electrode and negative electrode main contactors are welded when it is determined that the voltage across the smoothing capacitor has not decreased;
Closing the precharge contactor of either one of the positive and negative precharge contactors after it is determined that the voltage across the smoothing capacitor has decreased;
determining whether the voltage across the smoothing capacitor has increased before and after closing the one pole precharge contactor;
a step of determining that the main contactor of the other pole is welded when it is determined that the voltage value across the smoothing capacitor has increased;
opening the precharge contactor of the one pole and closing the precharge contactor of the other pole after determining that the voltage value across the smoothing capacitor has not increased;
determining whether the voltage across the smoothing capacitor has increased before and after closing the precharge contactor of the other pole;
7. The power supply according to claim 6, further comprising a step of determining that the one pole of the main contactor is welded when it is determined that the voltage across the smoothing capacitor has increased. How the system is controlled. A power supply system mounted on an electric vehicle,
a positive electrode main contactor provided on a positive electrode power line connecting a positive electrode of a DC power supply and an electrical load including a smoothing capacitor;
a positive precharge contactor and a positive precharge resistor connected to the positive power line in parallel with the positive main contactor;
a negative electrode main contactor provided on a negative electrode power line connecting the negative electrode of the DC power supply and the electrical load;
a negative precharge contactor and a negative precharge resistor connected to the negative power line in parallel with the negative main contactor;
When starting the connection between the DC power supply and the electric load, after the smoothing capacitor is precharged by closing the positive and negative precharge contactors, one of the positive and negative main contactors is precharged. a controller that closes the contactor and then closes the other main contactor;
The power supply system according to claim 1, wherein the control device changes the order of closing the positive and negative main contactors after the precharging is completed according to a predetermined condition.

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