JP5125155B2 - Power supply control device and power supply control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power control device capable of instantly judging the completion of operation of an electric load and the stoppage of power supply to the electric load on a system to supply power to the electric load from a battery etc. and a power control method. <P>SOLUTION: This power control device supplies power to the electric load of a vehicle. The power control device is furnished with a voltage transformation circuit, an electric current detection part and a control part. The voltage transformation circuit transforms power supplied from at least one battery to prescribed voltage and supplies it to the electric load. The electric current detection part detects an output electric current to the electric load from the voltage transformation circuit. The control part controls movement of the voltage transformation circuit. The control part judges finish of the movement of the electric load in accordance with electric current value detected by the electric current detection part and stops voltage transforming movement of the voltage transformation circuit after finishing the movement of the electric load. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a power supply control device and a power supply control method for supplying power to an electric load, and more particularly, to a power supply control device and a power supply control method for stopping power supply to the electric load in response to the operation stop of the electric load.

  Conventionally, a vehicle equipped with a hybrid system combining an internal combustion engine and an electric motor has been put into practical use. In such a hybrid system, a battery that supplies electric power of a high potential (for example, about 288 V) to an electric motor is used. This battery uses a high-voltage nickel metal hydride battery or the like, and is generally called a main battery.

In addition, an electric power steering device that assists the rotational operation force by the electric motor in accordance with the rotational operation given to the steering wheel is also mounted on the vehicle equipped with the hybrid system. For example, a power supply control device that supplies electric power lower than the high potential (medium potential, for example, about 42 V) to an electric power steering device is disclosed (for example, see Patent Document 1). The power supply control device disclosed in Patent Document 1 is a vehicle equipped with the hybrid system, in which a high potential from a main battery is stepped down to a middle potential by a DC-DC converter and power is supplied to the electric power steering device. Done.
JP 2006-213273 A

  However, the power supply control device disclosed in Patent Document 1 does not consider the power supply when the ignition switch of the vehicle is turned off (that is, the current supplied to the ignition device or the like of the internal combustion engine is turned off). For example, when the ignition switch is turned off, if the energization of the electric motor of the electric power steering device is immediately stopped, the assisting force (assisting force) to the steering wheel suddenly disappears.

  In order to prevent such deterioration of the steering feeling, a gradual change process may be performed in a general vehicle not equipped with a hybrid system. This gradual change process is a control for gradually decreasing the amount of current supplied to the electric motor during a period from when the ignition switch is switched from ON to OFF until the energization of the electric motor of the electric power steering device is stopped. The assist force will change gradually. As a result, the steering feeling after turning off the ignition switch is improved.

  However, when the above-described gradual change process is simply applied to a vehicle equipped with the hybrid system, information indicating that the gradual change process is completed is necessary to stop the power supply to the electric power steering apparatus. .

  For example, as shown in the timing chart of FIG. 8, in response to the ignition switch being changed from ON to OFF, the gradual change process of the electric power steering device is started (arrow F in the drawing). Next, when the gradual change process is completed, the electric power steering apparatus notifies the DC-DC converter of a notification indicating that (the illustrated arrow G). Then, the DC-DC converter stops the step-down operation and notifies that the use of power from the main battery is stopped. In response to this notification, the system main relay provided on the power supply line of the main battery is shut off (arrow H in the figure).

  Thus, when the above-described gradual change process is simply applied to a vehicle equipped with the hybrid system, information indicating that the gradual change process is complete may be notified from the electric power steering apparatus to the DC-DC converter. Necessary. Therefore, a communication line between the electric power steering device and the DC-DC converter is also required, which causes a cost increase.

  SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a power supply control device and a power supply that can immediately determine the end of operation of an electric load and the stop of power supply to the electric load in a system that supplies electric power from a battery or the like. It is to provide a control method.

In order to achieve the above-described object, the present invention has the following features.
1st invention is a power supply control apparatus which supplies electric power with respect to the electric load of a vehicle. The power supply control device includes a transformer circuit, a current detection unit, and a control unit. The transformer circuit transforms electric power supplied from at least one battery into a predetermined voltage and supplies it to an electric load. The current detection unit detects an output current from the transformer circuit to the electric load. The control unit controls the operation of the transformer circuit. The control unit determines the end of the operation of the electric load based on the current value detected by the current detection unit, and stops the transformation operation of the transformer circuit after the end of the operation.

  According to a second invention, in the first invention, an ignition switch state detecting means is further provided. The ignition switch state detection means detects the on / off state of the ignition switch of the vehicle. The control unit determines the end of the operation of the electric load based on the current value detected by the current detection unit after the ignition switch is switched from on to off.

  In a third aspect based on the first aspect, the transformer circuit is constituted by a step-down circuit. The step-down circuit steps down the power supplied from the high-voltage battery to a predetermined voltage and supplies it to the electric load. The control unit further controls the operation of a relay for connecting / disconnecting a contact provided on the power supply line between the high voltage system battery and the step-down circuit. A control part interrupts | blocks a relay after completion | finish of operation | movement of an electrical load, and cuts a contact.

  According to a fourth invention, in the first invention, further provided with an ignition switch state detecting means and an energization control unit. The ignition switch state detection means detects the on / off state of the ignition switch of the vehicle. The energization control unit performs energization control of electric power supplied from the transformer circuit to the electric load. The energization control unit performs energization control by gradually decreasing the amount of current to the electric load from the detection time point when the ignition switch state detecting means detects that the ignition switch has been switched from on to off.

  A fifth invention is the electric power steering device according to the fourth invention, wherein at least one of the electric loads supplied with electric power by the power supply control device applies an assisting force to a rotation operation of a steering wheel of the vehicle. The energization control unit performs energization control by gradually decreasing the amount of current to the electric power steering device so that the assist force of the electric power steering device gradually decreases from the time of detection.

In a sixth aspect based on the first aspect, the transformer circuit includes a step-down circuit and a step-up circuit. The step-down circuit steps down the power supplied from the high-voltage battery to a predetermined voltage and supplies it to the electric load. The booster circuit boosts the power supplied from the low voltage system battery to a predetermined voltage and supplies it to the electric load. When operating the step-down circuit and supplying power to the electric load, the control unit stops the step-down operation of the step-down circuit after the operation of the electric load is completed. When operating the booster circuit and supplying electric power to the electrical load, the control unit stops the boosting operation of the booster circuit after the operation of the electrical load is completed.

  In a seventh aspect based on the first aspect, at least one of the electric loads to which the power supply control device supplies electric power is an electric power steering device for a vehicle.

  The eighth invention is a power supply control method for supplying electric power to an electric load of a vehicle. The power supply control method includes a voltage transformation step, a current detection step, and an operation determination step. In the voltage transformation step, the supplied electric power is transformed to a predetermined voltage and supplied to the electric load. The current detection step detects an output current to the electric load. The operation determination step determines the end of the operation of the electric load based on the current value detected in the current detection step. In the transforming step, the transforming operation is stopped after the operation determining step determines that the operation of the electric load has been completed.

  According to the first aspect of the present invention, since the operation of the electric load is judged based on the output current output to the electric load and the transformation operation is stopped, the state notification from the electric load becomes unnecessary and the power supply is stopped. Judgment can be made immediately.

  According to the second aspect of the invention, since the operation end of the electric load is determined based on the output current after the ignition switch is turned off from ON, it is erroneously recognized that the output current changes when the ignition switch is on. Can be prevented. Further, it is possible to immediately determine the end of the operation of the electric load by limiting the electric load to continue the operation even after the ignition switch is turned off.

  According to the third aspect of the invention, a relay such as a system main relay provided on the power supply line from the high voltage system battery is in a connected state for a period in which power supply is required for the electric load to operate. Therefore, stable power supply from the high-voltage battery to the electric load can be performed. Further, since the step-down circuit is in a stopped state when the relay is shut off, it is possible to prevent the contact of the relay from being welded and to improve the durability of the relay.

  According to the fourth aspect, when the ignition switch is turned from ON to OFF, the electric load is changed from ON to OFF after the ignition switch is changed from ON to OFF by performing a gradual change process of the electric load. It is possible to improve the operational feeling when performing.

  According to the fifth aspect of the invention, when the ignition switch is turned from ON to OFF, the steering feeling after the ignition switch is changed from ON to OFF is improved by performing a gradual change process of the electric power steering device. Can do.

  According to the sixth aspect of the invention, in the power supply system that is supplied with power from the high-voltage system battery and the low-voltage system battery, the end of the operation of the electrical load is determined based on each output current that is output to the electrical load. Thus, the transformation operation is stopped, so that the state notification from the electric load is unnecessary, and it is possible to immediately determine the stop of the power supply.

  According to the seventh aspect of the present invention, since the operation stop of the electric power steering device mounted on the vehicle is determined based on the output current, the state notification from the electric power steering device becomes unnecessary, and the rotational operation force is assisted. It is possible to immediately determine the power supply stop without sudden disappearance.

Moreover, according to the power supply control method of the present invention, the same effects as those of the power supply control device described above can be obtained.

(First embodiment)
Hereinafter, with reference to FIGS. 1-4, the electric power supply system containing the power supply control device which concerns on the 1st Embodiment of this invention is demonstrated. Typically, the power supply system is installed in a vehicle equipped with a hybrid system. FIG. 1 is a schematic configuration diagram illustrating an example of a partial configuration of the power supply system. FIG. 2 is a flowchart showing an example of the operation of the HV-ECU 3 included in the power supply system. FIG. 3 is a flowchart showing an example of the operation of the microcomputer 55a included in the power supply system. FIG. 4 is a timing chart of power supply control in the power supply system.

  In FIG. 1, the power supply system supplies power from the high voltage system battery 1 to each electric load provided in the vehicle. Typically, there are an inverter and an air conditioner (not shown) as an electric load to which power from the high voltage battery 1 is supplied. Here, the inverter converts the DC power supplied from the high voltage system battery 1 into three phases, and controls energization of the electric motor (main motor) for driving the vehicle. Moreover, there is an electric power steering device as an electric load to which electric power from the high voltage system battery 1 is supplied. In the example of FIG. 1, electric power from the high-voltage battery 1 is supplied to an electric motor 7 via an EPS-ECU (Electric Power Steering-Electronic Control Unit) 6. The high-voltage battery 1 supplies power to electric loads other than the above-described examples of electric loads, but detailed description thereof is omitted here.

  The high-voltage battery 1 is a battery that supplies electric power of a high potential (for example, about 288 V) mainly to an electric motor in a hybrid system. The high voltage battery 1 is a high voltage nickel metal hydride battery or the like, and is generally called a main battery. Further, a system main relay (hereinafter referred to as SMR) 2 is provided on the power supply line of the high voltage battery 1, and power is supplied from the high voltage battery 1 by turning the SMR 2 on and off. Or power interruption is switched. The power supply line of the high voltage battery 1 is branched and connected to the load of the SMR 2 such as the above-described inverter and air conditioner.

  The vehicle is equipped with an electric power steering device that assists the rotational operation force by the electric motor 7 in accordance with the rotation operation given to the steering wheel by the driver. The electric motor 7 generates a driving force in the rotation direction of the steering shaft according to the rotation operation, and applies an assist force according to the rotation operation applied to the steering wheel. For example, the electric motor 7 is constituted by a three-phase motor, and its driving is controlled by the EPS-ECU 6.

  The EPS-ECU 6 calculates an energization amount to the electric motor 7 and drives and controls the electric motor 7 according to the energization amount. For example, the EPS-ECU 6 includes a three-phase inverter to which power from the DC-DC converter 5a is supplied, and power is supplied to each phase of the electric motor 7 from the three-phase inverter. The EPS-ECU 6 controls the amount of current supplied to the electric motor 7 based on information such as the motor rotation angle of the electric motor 7, the amount of current flowing through each phase of the electric motor 7, the steering torque, and the vehicle speed of the vehicle.

Specifically, the EPS-ECU 6 includes a control circuit and a drive circuit that controls energization of the electric motor 7. The electric motor 7 applies an assisting force in accordance with a rotational operation applied to the steering wheel, and is attached to the steering shaft through a speed reduction mechanism or the like so as to transmit torque. A torque sensor is attached to the steering shaft, and the torque sensor detects a steering torque acting on the steering shaft and outputs a steering torque signal indicating the steering torque to the control unit.

  The control unit includes a microcomputer, various interfaces, and a memory. The control unit is connected to a torque sensor, a vehicle speed sensor, an engine speed sensor, and a shift position sensor via an interface. The control unit is connected to the drive circuit via an interface, and controls the conduction state of the drive circuit based on a command.

  The drive circuit includes a plurality of switching elements (for example, six MOSFETs) whose gates are connected to the control unit, and receives power supply from the high-voltage battery 1 and the low-voltage battery 8. And according to control of the said control part, a switching element is selectively made into a conduction state, an electric current flows into any phase of the electric motor 7, and the electric motor 7 rotates to one direction or the other direction. In the above description, the example in which the electric motor 7 is configured by a three-phase brushless motor and is driven and controlled by a three-phase inverter is used. However, the present invention can employ various motors and driving circuits.

  The control unit of the EPS-ECU 6 calculates a target assist torque to be applied to the steering wheel using, for example, operation torque information obtained from the torque sensor and vehicle speed information obtained from the vehicle speed sensor. Specifically, the control unit sets a target assist torque corresponding to the operation torque for each vehicle speed range (low speed, medium low speed, medium high speed, high speed, etc.). Then, the control unit sets the target assist torque to increase as the operation torque increases, and to decrease the target assist torque as the vehicle speed increases with respect to the same operation torque.

  The control unit obtains the energization time (for example, duty ratio) of each switching element of the drive circuit so that the electric motor 7 generates the calculated target assist torque, and the switching element is turned ON− according to the energization time. Perform OFF control.

  Here, when the ignition switch 10 of the vehicle is changed from ON to OFF, the control unit of the EPS-ECU 6 does not immediately set the target assist torque to 0, but uses the operation torque information and the vehicle speed information. Thus, the target assist torque is set to gradually decrease. With this setting, when the ignition switch 10 is changed from ON to OFF, the assist force applied to the steering wheel gradually decreases to zero. Specifically, during the period from when the ignition switch 10 is switched from ON to OFF until the energization of the electric motor 7 of the electric power steering device is stopped, the amount of current supplied to the electric motor 7 is gradually reduced, and electric The energization to the motor 7 is stopped (gradual change process). This gradual change process improves the steering feeling after the ignition switch 10 is turned off.

  The electric power steering device has a medium potential (for example, about 42 V) between the high potential and the potential of the power supplied from the low voltage battery 8 (for example, about 12 V, hereinafter referred to as a low potential). Power is supplied. In the power supply system of the present embodiment, a power storage mechanism dedicated to medium potential is not provided, and the high potential from the high-voltage system battery 1 is increased to the above-described medium potential in consideration of the power consumption of the electric power steering device. The electric power is supplied to the electric power steering apparatus.

  The DC-DC converter 5a includes an inverter 51, a transformer 52, a rectifier circuit 53, a current sensor 54, and a microcomputer 55a. As described above, the DC-DC converter 5a steps down the high potential from the high voltage battery 1 to the intermediate potential and supplies power to the electric load.

  The high potential DC power output from the high voltage battery 1 is input to the DC-DC converter 5a. The high potential power input to the DC-DC converter 5 a is converted into alternating current by the inverter 51 and output to the transformer 52 via the current sensor 54. The transformer 52 steps down the electric power converted by the inverter 51 from a high potential to a medium potential and outputs it to the rectifier circuit 53. Then, the rectifier circuit 53 converts the medium potential AC power into DC and outputs it to the EPS-ECU 6. The current sensor 54 detects a primary current supplied to the primary side of the transformer 52 and outputs the current value AH to the microcomputer 55a.

  The microcomputer 55a monitors the output voltage of the DC-DC converter 5a and feedback-controls the operation of the step-down circuit (inverter 51, transformer 52, rectifier circuit 53) so that the output voltage becomes the target voltage. Further, the microcomputer 55a receives power supply from the auxiliary battery. For example, the microcomputer 55a monitors the output voltage of the DC-DC converter 5a and feedback-controls the operation of the step-down circuit so that the output voltage becomes a predetermined voltage (the intermediate potential). Further, the microcomputer 55a monitors the current in the DC-DC converter 5a based on the current value detected by the current sensor 54, and prevents overcurrent or the like in the DC-DC converter 5a or an electric load. Further, the microcomputer 55a monitors the ON / OFF operation of the ignition switch 10. Note that the microcomputer 55a performs information notification (specifically, notification indicating the state of the DC-DC converter 5a) to the hybrid control device (HV-Electronic Control Unit; hereinafter referred to as HV-ECU) 3. A communication line from the microcomputer 55a to the HV-ECU 3 is provided.

  The HV-ECU 3 is configured by a microcomputer or the like. The HV-ECU 3 calculates the engine output and motor torque according to the driving state of the vehicle, and controls the output of the inverter for the main motor. The HV-ECU 3 also performs ON / OFF control of the SMR 2 in addition to the vehicle hybrid system.

  Hereinafter, the operation of the power supply system will be described with reference to FIGS. 2 and 3. FIG. 2 is a flowchart showing an example of the operation of the HV-ECU 3 included in the power supply control device, and is stored as a control program in a storage area (not shown) used by the HV-ECU 3. Then, in response to the ignition switch 10 being turned on, the HV-ECU 3 executes the control program, thereby realizing a power supply operation described later. FIG. 3 is a flowchart showing an example of the operation of the microcomputer 55a included in the power supply control device, and is stored as a control program in a storage area (not shown) used by the microcomputer 55a. Then, when the ignition switch 10 is turned on, the microcomputer 55a executes the control program, thereby realizing a power supply operation described later. In the following description, the power supply operation to the electric power steering apparatus according to the change of the ignition switch 10 from ON to OFF will be mainly described, and detailed description of other operations will be omitted.

  In FIG. 2, the HV-ECU 3 determines whether or not the ignition switch 10 has been changed from ON to OFF (step S51). Then, when the ignition switch 10 is changed from ON to OFF, the HV-ECU 3 advances the process to the next step S52. On the other hand, the HV-ECU 3 repeats the process of step S51 when the ignition switch 10 is in the ON state.

  In step S52, the HV-ECU 3 stops the electrical load connected to the power supply line of the high voltage battery 1 and advances the process to the next step. For example, the electric load to be stopped in step S52 is the main motor inverter or the air conditioner described above.

Next, the HV-ECU 3 waits to receive a high voltage power supply use stop notification from the microcomputer 55a (step S53). Here, the high-voltage power supply use stop notification is a command that the microcomputer 55a transmits to the HV-ECU 3 through the signal line by a process in step S65 described later. And HV-ECU3 advances a process to following step S54, when a high voltage power supply use stop notification is received.

  In step S54, the HV-ECU 3 shuts off the SMR 2 and ends the process according to the flowchart. By shutting off the SMR 2, the power from the high voltage battery 1 is switched to the shut off state.

  On the other hand, in FIG. 3, the microcomputer 55a determines whether or not the ignition switch 10 has been changed from ON to OFF (step S61). Then, when the ignition switch 10 is changed from ON to OFF, the microcomputer 55a advances the process to the next step S62. On the other hand, the microcomputer 55a repeats the process of step S61 when the ignition switch 10 is in the ON state.

  In step S62, the microcomputer 55a acquires the current value AH detected by the current sensor 54. Next, the microcomputer 55a determines whether or not the current value AH acquired in step S62 is 0 A (ampere) (step S63). Then, when the current value AH is 0 A, the microcomputer 55a proceeds to the next step S64. On the other hand, if the current value AH is not 0A, the microcomputer 55a returns to step S62 and repeats the process.

  In step S64, the microcomputer 55a stops the step-down operation by the inverter 51, the transformer 52, and the rectifier circuit 53, and advances the processing to the next step. By stopping the step-down operation by the inverter 51, the transformer 52, and the rectifier circuit 53, the power supply from the high voltage system battery 1 to the electric power steering apparatus is stopped.

  Next, the microcomputer 55a transmits to the HV-ECU 3 a high voltage power supply use stop notification indicating that the DC-DC converter 5a has finished using the power from the high voltage system battery 1 (step S65), and the flowchart shown in FIG. The process by is terminated. Specifically, the microcomputer 55a transmits a high-voltage power supply use stop notification to the HV-ECU 3 via the signal line between the HV-ECU 3 and the microcomputer 55a.

  Next, the operation timing of the power supply system based on the flowcharts shown in FIGS. 2 and 3 will be described with reference to FIG. FIG. 4 is a timing chart showing an example of operation timing in the power supply system according to the present embodiment. Note that the timing chart shown in FIG. 4 shows that the ignition switch 10 is turned on when the high potential power supplied from the high potential power supply system is stepped down to the middle potential by the step-down circuit 51 and supplied to the electric load. The operation timing when changed to OFF is shown.

  In FIG. 4, the ignition switch 10 is changed from ON to OFF. Then, the control unit of the EPS-ECU 6 gradually sets the assist force by setting the target assist torque to gradually decrease in response to the ignition switch 10 being changed from ON to OFF (shown arrow A). A gradual change process is performed to reduce it to 0%.

Here, when the EPS-ECU 6 performs a gradual change process for gradually reducing the assist force to 0%, the DC-DC converter is accompanied by a decrease in the amount of electric power according to the progress of the gradual change process. The output current from 5a to the EPS-ECU 6 also gradually decreases, and when the gradual change process ends, the output current becomes 0A. More specifically, as described above, the DC-DC converter 5a controls the output voltage to the EPS-ECU 6 to be a medium potential, and when the amount of power required by the EPS-ECU 6 decreases, the EPS-ECU 6 decreases. -The output current to the ECU 6 also decreases. In response to the gradual decrease in the output current, the secondary current of the transformer 52 gradually decreases, and when the gradual change process is completed, the secondary current also becomes 0A. Then, the primary current of the transformer 52 gradually decreases according to the current transformation ratio between the primary current and the secondary current of the transformer 52 (the reciprocal of the turns ratio of the transformer 52), and when the above-described gradual change processing is completed. Therefore, the primary current also becomes 0A. On the other hand, the current sensor 54 detects the primary current of the transformer 52 and outputs the detection result to the microcomputer 55a as the current value AH. That is, the microcomputer 55a can know that the gradual change process performed by the EPS-ECU 6 has ended by detecting that the current value AH acquired from the current sensor 54 indicates 0A (Yes in step S63). .

  The microcomputer 55a of the DC-DC converter 5a stops the step-down operation by the inverter 51, the transformer 52, and the rectifier circuit 53 in response to the current value AH being reduced to 0A (arrow B in the figure). As a result, power supply from the DC-DC converter 5a to the electric power steering apparatus is stopped. Here, since the step-down operation is stopped after the gradual change processing of the EPS-ECU 6 is completed, stable power supply is performed during a period in which power supply to the electric power steering apparatus is necessary.

  Next, the microcomputer 55a notifies the HV-ECU 3 that the use of the high-voltage power source is stopped, which indicates that the use of the electric power from the high voltage system battery 1 is finished. In response to this high-voltage power supply stoppage, the HV-ECU 3 shuts off the SMR 2 (arrow C in the figure). By shutting off the SMR 2, the power from the high voltage battery 1 is switched to the shut off state.

  As is apparent from a comparison between FIG. 4 and the conventional operation timing (see FIG. 8), there is no need for a process of notifying the DC-DC converter 5a of a notification indicating that the gradual change process has been completed. is there. Therefore, it is conceivable that the responsiveness from when the ignition switch 10 is turned off for the time required for the above process until the SMR 2 is shut off is improved. In this case, since the timing at which the hybrid system can be restarted becomes earlier, it can be expected that the startability of the hybrid system is improved.

  As described above, according to the power supply control device according to the first embodiment, it is determined whether or not to stop supplying power to the electric load based on the output current output to the electric load. It is possible to immediately determine the power supply stoppage. In addition, since the status notification from the electric load is not required, if the information notification between these is unnecessary in other processes, the process for transmitting the communication line for transmitting these notifications and the contents of the notification is performed. It becomes unnecessary. Furthermore, since the gradual change process of the electric power steering device is reliably performed when the ignition switch is turned from ON to OFF, the steering feeling after the ignition switch is changed from ON to OFF can be improved.

  Note that the process of stopping the step-down operation in step S64 described above is performed immediately when the current value AH becomes 0 A, but the operation may be performed at another timing. For example, the step-down operation may be stopped a predetermined time after the current value AH becomes 0A. As described above, by stopping the step-down operation after a predetermined time from the time when the current value AH becomes 0 A, the gradual change processing due to the manufacturing variation of each device (for example, the variation in detection accuracy of the current sensor 54) or the like. The variation in the end determination can be absorbed in the predetermined time.

In the above description, an example in which the current sensor 54 is installed between the inverter 51 and the transformer 52 is used. This is because the existing current sensor 54 provided for monitoring an overcurrent in the DC-DC converter 5a, an overcurrent to the electric load, or the like is used. When it is not expected to suppress the cost increase by using such an existing circuit, the current sensor 54 may be installed at another position. For example, it goes without saying that the present invention can be realized even if the current sensor 54 is installed at another position such as between the transformer 52 and the rectifier circuit 53, immediately after the rectifier circuit 53, or immediately before the EPS-ECU 6.

(Second Embodiment)
Hereinafter, with reference to FIGS. 5-7, the electric power supply system containing the power supply control apparatus which concerns on the 2nd Embodiment of this invention is demonstrated. Typically, the power supply system is installed in a vehicle equipped with a hybrid system. FIG. 5 is a schematic configuration diagram illustrating an example of a partial configuration of the power supply system. FIG. 6 is a flowchart showing an example of the operation of the microcomputer 55b included in the power supply system. FIG. 7 is a timing chart of power supply control in the power supply system.

  In FIG. 5, the power supply system supplies the electric power from the high voltage system battery 1 and the low voltage system battery 8 to each electric load provided in the vehicle. Typically, there are an inverter and an air conditioner as the electric load to which the electric power from the high voltage battery 1 is supplied, as in the first embodiment. In addition, there is an electric power steering device as an electric load to which power from the high voltage system battery 1 or the low voltage system battery 8 is supplied. In the example of FIG. 5, the electric power from the high voltage system battery 1 or the low voltage system battery 8 is supplied to the electric motor 7 via the EPS-ECU 6. In addition, although the high voltage system battery 1 and the low voltage system battery 8 supply electric power also to electric loads other than the example of the electric load mentioned above, detailed description is abbreviate | omitted here.

  In the power supply system according to the second embodiment, the low-voltage power supply can be further performed as compared with the first embodiment. Hereinafter, in the description of the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The low-voltage system battery 8 is a battery that mainly supplies low-potential (for example, about 12 V) power to the auxiliary equipment of the vehicle. The low voltage battery 8 uses a lead storage battery or the like, and is generally called an auxiliary battery. The low voltage battery 8 supplies power to various electric loads provided in the vehicle, but detailed description thereof is omitted here. The power supply line of the high voltage battery 1 is connected to a step-down circuit (not shown) that steps down the high potential to the low potential, and the power stepped down by the step-down circuit is supplied to the low voltage battery 8. Charged. Similarly to the other electric loads, the step-down circuit is branched and connected from the load side of the SMR 2 in the power supply line of the high voltage battery 1.

  The EPS-ECU 6 is supplied with electric power having a medium potential (for example, about 42 V) between the high potential and the low potential. Even in the power supply system according to the present embodiment, a power storage mechanism dedicated to the intermediate potential is not provided, and the high potential from the high-voltage battery 1 is mainly DC- The voltage is stepped down by the DC converter 5b, and electric power is supplied to the electric power steering apparatus. In this case, when the high potential power system is abnormal, the low potential from the low voltage system battery 8 is boosted to the middle potential by the DC-DC converter 5b as a temporary backup power source and supplied to the electric power steering device. Supply.

  The DC-DC converter 5b includes a microcomputer 55b, a booster circuit 56, and a current sensor 57 in addition to the inverter 51, the transformer 52, the rectifier circuit 53, and the current sensor 54 described above. As described above, the DC-DC converter 5b steps down the high potential from the high voltage system battery 1 to the intermediate potential or boosts the low potential from the low voltage system battery 8 to the intermediate potential and supplies the electric load to the electric load. .

When the high potential power system is abnormal, power is supplied from the low voltage system battery 8 to the EPS-ECU 6. The low potential direct current power output from the low voltage system battery 8 is input to the booster circuit 56 of the DC-DC converter 5b. Typically, the booster circuit 56 includes a booster coil and a diode provided on the power supply line, a switching element (for example, a MOS) that is grounded between the booster coil and the diode, and the like. Then, by causing intermittent current from the low voltage battery 8 to flow through the booster coil, electric power is generated in the booster coil to boost the low potential power to the middle potential. The boosted medium potential power is rectified by a diode and output to the EPS-ECU 6. A current sensor 57 is provided on the power supply line between the boosting coil of the boosting circuit 56 and the diode. Current sensor 57 detects the current flowing from the boost coil to the diode, and outputs the current value AL to microcomputer 55b.

  The microcomputer 55b monitors the output voltage of the DC-DC converter 5b and controls the operation of the step-down circuit (inverter 51, transformer 52, rectifier circuit 53) and step-up circuit 56 so that the output voltage becomes the target voltage. Further, the microcomputer 55b receives power supply from the low voltage system battery 8. For example, the microcomputer 55b monitors the output voltage of the DC-DC converter 5b, and feedback-controls the operation of the step-down circuit or the step-up circuit 56 so that the output voltage becomes a predetermined voltage (the intermediate potential). In addition, the microcomputer 55b monitors the output current of the DC-DC converter 5b based on the current values detected by the current sensor 54 and the current sensor 57, and prevents overcurrent to the EPS-ECU 6 and the like. Further, the microcomputer 55b monitors the ON / OFF operation of the ignition switch 10. A communication line from the microcomputer 55b to the HV-ECU 3 is provided in order to notify the HV-ECU 3 (specifically, a notification indicating the state of the DC-DC converter 5b).

  Hereinafter, the operation of the power supply system will be described with reference to FIG. FIG. 6 is a flowchart showing an example of the operation of the microcomputer 55b included in the power supply control device, and is stored as a control program in a storage area (not shown) used by the microcomputer 55b. When the ignition switch 10 is turned on, the microcomputer 55b executes the control program, thereby realizing a power supply operation described later. In the following description, it is assumed that power is being supplied from the low voltage system battery 8 to the EPS-ECU 6 due to an abnormality in the high potential power system. In the power supply state, the power supply operation to the electric power steering apparatus according to the change of the ignition switch 10 from ON to OFF will be mainly described, and detailed description of the other power supply operations will be omitted. To do. Here, in a state where electric power is supplied from the low voltage system battery 8 to the EPS-ECU 6, the SMR 2 is already cut off, and the power supply from the high voltage system battery 1 is cut off.

  In FIG. 6, the microcomputer 55b determines whether or not the ignition switch 10 has been changed from ON to OFF (step S71). Then, when the ignition switch 10 is changed from ON to OFF, the microcomputer 55b advances the processing to the next step S72. On the other hand, the microcomputer 55b repeats the process of step S71 when the ignition switch 10 is in the ON state.

  In step S72, the microcomputer 55b acquires the current value AL detected by the current sensor 57. Next, the microcomputer 55b determines whether or not the current value AL acquired in step S72 is 0 A (step S73). Then, when the current value AL is 0 A, the microcomputer 55b proceeds to the next step S74. On the other hand, if the current value AL is not 0A, the microcomputer 55a returns to step S72 and repeats the process.

In step S74, the microcomputer 55b stops the boosting operation by the booster circuit 56, and ends the processing according to the flowchart. By stopping the boosting operation by the booster circuit 56, the power supply from the low voltage system battery 8 to the electric power steering device is stopped, and the power supply to the electric power steering device is stopped.

  Next, the operation timing of the power supply system based on the flowchart shown in FIG. 6 will be described with reference to FIG. FIG. 7 is a timing chart showing an example of operation timing in the power supply system according to the second embodiment. Here, the timing chart shown in FIG. 7 shows that the ignition switch 10 is ON when the low-potential power supplied from the low-potential power supply system is boosted to the middle potential by the booster circuit 56 and supplied to the electric load. The operation timing when changed from OFF to OFF is shown. That is, the microcomputer 55b has already stopped the boosting operation by the boosting circuit and has already notified the HV-ECU 3 that the high-voltage power supply has been stopped. Therefore, SMR2 is also in a cut-off state.

  In FIG. 7, the ignition switch 10 is changed from ON to OFF. Then, the control unit of the EPS-ECU 6 gradually sets the assist force by setting the target assist torque to gradually decrease in response to the ignition switch 10 being changed from ON to OFF (shown arrow D). A gradual change process is performed to reduce it to 0%.

  As described above, when the EPS-ECU 6 performs the gradual change process that gradually decreases the assist force to 0%, the DC-DC decreases with the reduction in the amount of electric power according to the progress of the gradual change process. The output current from the converter 5b to the EPS-ECU 6 also gradually decreases, and when the gradual change process is finished, the output current becomes 0A. On the other hand, the current sensor 57 detects the current between the boosting coil of the boosting circuit 56 and the diode, and outputs the detection result to the microcomputer 55b as the current value AL. That is, the microcomputer 55b can know that the gradual change process performed by the EPS-ECU 6 has ended by detecting that the current value AL acquired from the current sensor 57 indicates 0A (Yes in step S73). .

  The microcomputer 55b of the DC-DC converter 5b stops the step-up operation by the step-up circuit 56 in response to the decrease in the current value AL to 0 A (arrow E in the figure). As a result, power supply from the DC-DC converter 5b to the electric power steering apparatus is stopped. Here, since the step-up operation is stopped after the gradual change process of the EPS-ECU 6 is completed, stable power supply is performed during a period in which power supply to the electric power steering apparatus is necessary.

  As described above, according to the power supply control device according to the second embodiment, even when power is supplied from a low-potential battery, power is supplied to the electric load based on the output current output to the electric load. Since the stop is determined, the state notification from the electric load is not required, and the stop of the power supply can be immediately determined. In addition, since the status notification from the electric load is not required, if the information notification between these is unnecessary in other processes, the process for transmitting the communication line for transmitting these notifications and the contents of the notification is performed. It becomes unnecessary. Furthermore, since the gradual change process of the electric power steering device is reliably performed when the ignition switch is turned from ON to OFF, the steering feeling after the ignition switch is changed from ON to OFF can be improved.

  Note that the process of stopping the boosting operation in step S74 described above is performed immediately when the current value AL becomes 0 A, but the operation may be performed at another timing. For example, the boosting operation may be stopped after a predetermined time from when the current value AL becomes 0A. As described above, by stopping the step-up operation after a predetermined time from the time when the current value AL becomes 0 A, a gradual change process caused by manufacturing variations of each device (for example, variations in detection accuracy of the current sensor 57) or the like. The variation in the end determination can be absorbed in the predetermined time.

  In the above description, an example in which the current sensor 57 is installed between the boosting coil of the boosting circuit 56 and the diode is used. This is because the existing current sensor 57 provided for monitoring an overcurrent in the DC-DC converter 5b, an overcurrent to the electric load, or the like is used. If it is not expected to suppress the cost increase by using such an existing circuit, the current sensor 57 may be installed at another position. For example, it goes without saying that the present invention can be realized even if the current sensor 57 is installed in the DC-DC converter 5b or other position outside the DC-DC converter 5b, such as immediately after the booster circuit 56 or immediately before the EPS-ECU 6.

  In the power supply control device according to the second embodiment, the current sensor 54 is provided in the same manner as the power supply control device according to the first embodiment described above. Therefore, in the power supply control device according to the second embodiment, the high potential power supplied from the high potential battery (that is, the high voltage battery 1) is stepped down to the middle potential and supplied to the electric load. In this case, needless to say, if the current value AH output from the current sensor 54 is used, the same processing as in the first embodiment is possible. It is also possible to stop the power supply from the high potential system and stop the power supply from the low potential system based on the output from one current sensor. In this case, by providing the current sensor at a position where the current value by each power supply can be detected, such as immediately before the EPS-ECU 6, the present invention can be realized by one current sensor for any power supply. .

  In the above description, the electric power steering device is used as an example of the electric load that supplies the medium potential power. However, another electric load that needs to be supplied for a predetermined time after the ignition switch is turned off is supplied. It does not matter as a target.

  In the operation of step S52, the HV-ECU 3 stops the electric load connected to the power supply line of the high voltage battery 1, but the other control unit mounted on the vehicle stops the electric load. It doesn't matter. In the above description, an example in which a plurality of control units, each of which uses the HV-ECU 3, the microcomputer 55, and the EPS-ECU 6 as an example operates, may be operated according to other modes. For example, any one control unit of the HV-ECU 3, the microcomputer 55, and the EPS-ECU 6 may perform all the operations of the HV-ECU 3, the microcomputer 55, and the EPS-ECU 6 described above. In addition, a single control unit different from the HV-ECU 3, the microcomputer 55, and the EPS-ECU 6 may perform at least a part of the operations of the HV-ECU 3, the microcomputer 55, and the EPS-ECU 6 described above. In this case, the single control unit may be provided inside the DC-DC converter 5 or may be provided outside the DC-DC converter 5. Further, another control unit already installed in the vehicle may perform the operations of the HV-ECU 3, the microcomputer 55, and the EPS-ECU 6 described above.

  Moreover, although the example installed in the vehicle carrying a hybrid system was used in the description mentioned above, you may install in vehicles, such as an electric vehicle.

  Although the present invention has been described in detail above, the above description is merely illustrative of the present invention in all respects and is not intended to limit the scope thereof. It goes without saying that various improvements and modifications can be made without departing from the scope of the present invention.

  The power supply control device and the power supply control method according to the present invention are applicable to a system that supplies power to an electrical load from at least one battery because it is not necessary to notify the status from the electrical load and can immediately determine whether to stop power supply. it can.

1 is a schematic configuration diagram showing a partial configuration of a power supply system including a power supply control device according to a first embodiment of the present invention. The flowchart which shows an example of operation | movement of HV-ECU3 of FIG. The flowchart which shows an example of operation | movement of the microcomputer 55a of FIG. Timing chart of power supply control in the power supply system of FIG. The schematic block diagram which shows the structure of a part of electric power supply system containing the power supply control apparatus which concerns on the 2nd Embodiment of this invention. The flowchart which shows an example of operation | movement of the microcomputer 55b of FIG. Timing chart of power supply control in the power supply system of FIG. Timing chart of power supply control in a conventional power supply system

Explanation of symbols

1 ... High voltage battery 2 ... SMR
3 ... HV-ECU
5 ... DC-DC converter 51 ... Inverter 52 ... Transformer 53 ... Rectifier circuit 54, 57 ... Current sensor 55 ... Microcomputer 56 ... Booster circuit 6 ... EPS-ECU
7 ... Electric motor 8 ... Low voltage battery 10 ... Ignition switch

Claims (7)

A power supply control device for supplying power to an electric load of a vehicle,
A transformer circuit that transforms electric power supplied from at least one battery into a predetermined voltage and supplies the electric load to the electric load;
A current detector for detecting an output current from the transformer circuit to the electrical load;
A control unit for controlling the operation of the transformer circuit,
The transformer circuit includes a step-down circuit that steps down power supplied from a high-voltage battery to the predetermined voltage and supplies the electric load to the electric load.
The control unit determines the end of operation of the electric load based on the current value detected by the current detection unit, stops the transformation operation of the transformer circuit after the end of the operation ,
The control unit further controls the operation of a relay for connecting / disconnecting a contact provided on a power supply line between the high-voltage battery and the step-down circuit,
The said control part is a power supply control apparatus which interrupts | blocks the said relay and cut | disconnects the said contact after the transformation operation | movement of the said transformation circuit stops . Ignition switch state detecting means for detecting an on / off state of the ignition switch of the vehicle, further comprising:
The power supply control device according to claim 1, wherein the control unit determines the end of the operation of the electric load based on a current value detected by the current detection unit after the ignition switch is switched from on to off. An ignition switch state detecting means for detecting an on / off state of the ignition switch of the vehicle;
An energization control unit that performs energization control of electric power supplied from the transformer circuit to the electrical load;
2. The energization control unit performs energization control by gradually decreasing the amount of current to the electric load from a detection time point when the ignition switch state detection unit detects that the ignition switch has been switched from on to off. The power supply control device described in 1. At least one of the electric loads to which the power supply control device supplies electric power is an electric power steering device that applies an assisting force to a rotation operation of the steering wheel of the vehicle,
The power supply control device according to claim 3 , wherein the energization control unit performs energization control by gradually decreasing a current amount to the electric power steering device so that the assist force of the electric power steering device gradually decreases from the detection time point. The transformer circuit is:
A step-down circuit that steps down power supplied from a high-voltage battery to the predetermined voltage and supplies the electric load;
A voltage boosting circuit configured to boost the power supplied from the low-voltage battery to the predetermined voltage and to supply the electric load;
The control unit, when operating the step-down circuit and supplying power to the electric load, stops the step-down operation of the step-down circuit after the operation of the electric load,
2. The power supply control device according to claim 1, wherein the control unit stops the boosting operation of the boosting circuit after the operation of the electrical load ends when the boosting circuit is operated to supply power to the electrical load.   The power supply control device according to claim 1, wherein at least one of the electric loads to which the power supply control device supplies electric power is an electric power steering device of the vehicle. A power supply control method for supplying electric power to an electric load of a vehicle,
Transforming supplied power to a predetermined voltage and supplying the electric load to the electric load;
A current detection step of detecting an output current to the electrical load;
An operation determination step of determining the end of the operation of the electric load based on the current value detected in the current detection step,
In the step of transforming, the power supplied from the high-voltage battery is stepped down to the predetermined voltage by a step-down circuit and supplied to the electric load.
In the transformation step, after the operation judging step judges that the operation of the electric load is finished, the transformation operation is stopped .
The power supply control method further includes a relay control step of controlling a relay for connecting / disconnecting a contact provided on a power supply line between the high voltage battery and the step-down circuit,
The relay control step is a power supply control method in which the relay is disconnected and the contact is disconnected after the transformation operation in the transformation step is stopped .

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