JP6040845B2 - Power supply voltage control device - Google Patents

Description

  The present invention relates to a power supply voltage control device that controls a power supply voltage supplied to an in-vehicle device.

  When the engine is started, a large amount of power is supplied from the in-vehicle battery to the starter, so that the battery voltage temporarily decreases. Therefore, when the engine is started in a state where the battery is exhausted, the battery voltage drops below the reset voltage, and reset may occur in the electronic control device mounted on the vehicle.

  In order to suppress the occurrence of reset due to such a battery voltage drop, a technique is known in which an electronic control device has a booster circuit that raises the battery voltage to a predetermined value or higher when the battery voltage becomes a predetermined value or lower. (For example, see Patent Document 1).

JP-A-3-294660

  However, in the technique described in Patent Document 1, since the battery voltage is directly supplied to the electronic control device, there is a possibility that heat generation due to power loss increases in the electronic control device. This can be solved by dropping the battery voltage with a step-down circuit. However, since the step-up circuit and the step-down circuit are connected in series, there is a problem that the output ripple voltage is increased, the control stability is deteriorated, and the transient response is also deteriorated.

  The present invention has been made in view of such problems, and an object thereof is to ensure control stability and transient response of a power supply voltage control device.

  In the power supply voltage control apparatus of the present invention made to achieve the above object, the booster circuit boosts the power supply voltage to the boosting set voltage value when the power supply voltage is equal to or lower than a preset boosting voltage value. The operation is performed, and when the power supply voltage is equal to or higher than a preset step-down set voltage value, the step-down circuit executes a step-down operation for dropping the power supply voltage to the step-down set voltage value. Further, the boost setting voltage value is set to be smaller than the step-down setting voltage value, and the booster circuit is configured not to perform the boost operation when the power supply voltage exceeds the boost setting voltage value. The step-down circuit is configured not to perform the step-down operation when the power supply voltage is less than the step-down set voltage value.

  In the power supply voltage control apparatus configured as described above, the booster circuit does not perform the boosting operation when the power supply voltage is equal to or higher than the step-down set voltage value and the step-down circuit is performing the step-down operation. Further, when the booster circuit is performing the boosting operation due to the power supply voltage being equal to or lower than the boosting set voltage value, the step-down circuit does not execute the step-down operation.

That is, in the power supply voltage control apparatus of the present invention, the booster circuit and the step-down circuit do not execute the operation at the same time, so that control stability and transient response can be ensured.
Further, in the power supply voltage control device of the present invention, the boost setting voltage value is set to be smaller than the step-down setting voltage value, so that when the power supply voltage is between the boost setting voltage value and the step-down setting voltage value, Both the step-up circuit and the step-down circuit do not operate. Therefore, by increasing the difference between the boost setting voltage value and the step-down setting voltage value, it is possible to set the power supply voltage region where both the boost circuit and the step-down circuit do not operate. As a result, even when the power supply voltage fluctuates and when the circuit current changes due to load fluctuations, the step-up and step-down exclusive operations can be performed, and control stability and transient response can be ensured.

It is a block diagram which shows ECU1 and the peripheral device of ECU1. 3 is a flowchart showing the operation of the internal power supply circuit 15. 4 is a graph showing battery voltage characteristics of output voltage of a step-down circuit 44.

Embodiments of the present invention will be described below with reference to the drawings.
An electronic control unit (Electronic Control Unit) 1 (hereinafter referred to as ECU 1) of the present embodiment is mounted on a vehicle and controls a starter for starting an engine of the vehicle.

As shown in FIG. 1, a key switch 2, a main relay 3, a battery 4, and fuses 5 and 6 are provided outside the ECU 1 in the vehicle.
The key switch 2 is attached to an ignition key cylinder into which a vehicle key is inserted. The ignition key cylinder rotates the key of the inserted vehicle by the driver, and the four key positions of the off (OFF) position, accessory (ACC) position, ignition (IG) position and starter (ST) position are selected. It is switched to any one of these.

  The key switch 2 includes a battery terminal 21, an off terminal 22, an accessory terminal 23, an ignition terminal 24, and a starter terminal 25. The positive terminal of the battery 4 is connected to the battery terminal 21.

  The key switch 2 is connected to the battery terminal 21, the off terminal 22, and the accessory terminal 23 when the key position is an OFF (OFF) position, an accessory (ACC) position, an ignition (IG) position, and a starter (ST) position, respectively. The ignition terminal 24 and the starter terminal 25 are connected. Thereby, the key switch 2 switches the energization state of the vehicle according to the key position of the ignition key cylinder.

  The main relay 3 includes terminals 31 and 32, the terminal 31 is connected to the positive electrode of the battery 4 through the fuse 5, and the terminal 32 is connected to the ECU 1. The main relay 3 is turned on when the key position of the ignition key cylinder is the ignition position. Thereby, the terminal 31 and the terminal 32 are connected, and the battery voltage VB of the battery 4 is supplied to the ECU 1.

The ECU 1 includes a microcomputer 11, terminals 12 and 13, a starter switch detection circuit 14, and an internal power supply circuit 15.
The microcomputer 11 includes a CPU, a ROM, a RAM, an I / O, a bus line connecting these components, and the like, and executes various control processes based on a program stored in the ROM.

The terminal 12 is connected to the starter terminal 25 of the key switch 2 through the fuse 6. The terminal 13 is connected to the terminal 32 of the main relay 3.
The starter switch detection circuit 14 is connected to the terminal 12 and determines whether the key position is the starter position based on the voltage value applied to the terminal 12. When the starter switch detection circuit 14 determines that the key position is the starter position, the starter switch detection circuit 14 outputs a starter position notification signal indicating that the key position is the starter position.

  The internal power supply circuit 15 steps down the battery voltage VB input from the terminal 13 to generate a power supply voltage (hereinafter referred to as an internal power supply voltage) for operating the microcomputer 11, and outputs the generated internal power supply voltage to the microcomputer 11. To do.

The internal power supply circuit 15 includes a diode 41, a booster circuit 42, a diode 43, a step-down circuit 44, and a constant voltage circuit 45.
The diode 41 is a diode for preventing current backflow, and is installed on the power supply wiring VL <b> 1 connecting the terminal 13 and the step-down circuit 44 so that no current flows from the step-down circuit 44 toward the terminal 13. That is, the diode 41 has an anode connected to the terminal 13 and a cathode connected to the step-down circuit 44.

  The booster circuit 42 is connected to a power supply line VL2 that connects the terminal 13 and the booster circuit 42, and a power supply line VL3 that connects the stepdown circuit 44 and the booster circuit 42. Therefore, the booster circuit 42 boosts the battery voltage VB input via the power supply wiring VL2 to a preset boost setting voltage value V1, and outputs the boosted voltage via the power supply wiring VL3.

  The booster circuit 42 is configured such that a boosting operation is possible when the starter position notification signal is input from the starter switch detection circuit 14, and a boosting operation is prohibited when the starter position notification signal is not input. .

  The diode 43 is a diode for preventing current backflow. The anode is connected to the booster circuit 42 and the cathode is the diode 41 so that no current flows from the step-down circuit 44 to the booster circuit 42 on the power supply wiring VL3. Is connected to the connection point of the step-down circuit 44.

  The step-down circuit 44 inputs the battery voltage VB from the terminal 13 via the power supply line VL1 or the voltage output from the step-up circuit 42 via the power supply line VL3, and sets the input voltage to a preset step-down setting. Step down to voltage value V2 and output.

  The constant voltage circuit 45 further steps down the voltage input from the step-down circuit 44 to generate a power supply voltage (hereinafter referred to as an internal power supply voltage) for operating the microcomputer 11, and outputs the generated internal power supply voltage to the microcomputer 11. To do.

Next, the operation of the internal power supply circuit 15 will be described with reference to FIG.
As shown in FIG. 2, the internal power supply circuit 15 first determines in S10 whether or not the battery voltage VB is equal to or lower than the boost setting voltage value V1. If the battery voltage VB is equal to or lower than the boost setting voltage value V1 (S10: YES), it is determined in S20 whether the battery voltage VB is equal to or higher than the ECU start voltage value V3. The ECU starting voltage value V3 is a lower limit value of the battery voltage VB that can drive the starter to start the engine.

  Here, when the battery voltage VB is less than the ECU start voltage value V3 (S20: NO), both the booster circuit 42 and the step-down circuit 44 are not operated in S30. As a result, the battery voltage VB is supplied to the constant voltage circuit 45 without being boosted by the booster circuit 42 and stepped down by the step-down circuit 44. Then, when the process of S30 ends, the process proceeds to S10.

  On the other hand, if battery voltage VB is equal to or higher than ECU start voltage value V3 (S20: YES), whether the key position is the starter position based on the starter position notification signal from starter switch detection circuit 14 in S40. Judge whether or not. If the key position is the starter position (S40: YES), the step-up circuit 42 is activated and the step-down circuit 44 is not operated in S50. Thereby, the booster circuit 42 boosts the battery voltage VB to the boost set voltage value V1, and the voltage of the boost set voltage value V1 is supplied to the constant voltage circuit 45. Then, when the process of S50 ends, the process proceeds to S10. On the other hand, when the key position is not the starter position (S30: NO), the process proceeds to S30.

  If the battery voltage VB exceeds the boost setting voltage value V1 at S10 (S10: NO), it is determined at S60 whether the battery voltage VB is equal to or lower than the step-down setting voltage value V2. . If the battery voltage VB is equal to or lower than the step-down setting voltage value V2 (S60: YES), the process proceeds to S30.

  On the other hand, when the battery voltage VB exceeds the step-down set voltage value V2 (S60: NO), the step-down circuit 44 is operated and the step-up circuit 42 is not operated in S70. As a result, the battery voltage VB is stepped down to the step-down set voltage value V2 by the step-down circuit 44, and the voltage of the step-down set voltage value V2 is supplied to the constant voltage circuit 45. Then, when the process of S70 ends, the process proceeds to S10.

  In the internal power supply circuit 15 configured as described above, as shown in FIG. 3, when the battery voltage VB exceeds the step-down setting voltage value V2, the voltage of the step-down setting voltage value V2 is supplied to the constant voltage circuit 45. (See broken line L1). On the other hand, when the battery voltage VB exceeds the boost setting voltage value V1 and less than the step-down setting voltage value V2, the battery voltage VB is supplied to the constant voltage circuit 45 (see the solid line L2).

  When the battery voltage VB is equal to or higher than the ECU start voltage value V3 and equal to or lower than the boost setting voltage value V1, and the key position is the starter position, the voltage of the boost setting voltage value V1 is supplied to the constant voltage circuit 45. (Refer to the one-dot chain line L3) When the key position is not the starter position, the battery voltage VB is supplied to the constant voltage circuit 45 (see the dotted line L4).

When battery voltage VB is less than ECU start voltage value V3, battery voltage VB is supplied to constant voltage circuit 45 (see solid line L5).
In the internal power supply circuit 15 configured as described above, the booster circuit 42 boosts the battery voltage VB to the boost set voltage value V1 when the battery voltage VB is equal to or lower than the preset boost set voltage value V1. When the battery voltage VB is equal to or higher than the step-down set voltage value V2, the step-down circuit 44 executes a step-down operation for dropping the battery voltage VB to the step-down set voltage value V2. Further, the boost setting voltage value V1 is set to be smaller than the step-down setting voltage value V2, and the booster circuit 42 performs the boost operation when the battery voltage VB exceeds the boost setting voltage value V1. The step-down circuit 44 is configured not to execute, and is configured not to execute the step-down operation when the battery voltage VB is less than the step-down setting voltage value V2.

  In the internal power supply circuit 15 configured as described above, the booster circuit 42 does not perform the boost operation when the voltage drop circuit 44 is performing the step-down operation because the battery voltage VB is equal to or higher than the step-down set voltage value V2. In addition, when the battery voltage VB becomes equal to or lower than the boost setting voltage value V1 and the booster circuit 42 is performing a boost operation, the step-down circuit 44 does not perform the step-down operation.

That is, in the internal power supply circuit 15, since the booster circuit 42 and the step-down circuit 44 do not execute the operation at the same time, control stability and transient response can be ensured.
Further, in internal power supply circuit 15, since boost setting voltage value V1 is set to be smaller than step-down setting voltage value V2, battery voltage VB is between boost setting voltage value V1 and step-down setting voltage value V2. Both the step-up circuit 42 and the step-down circuit 44 do not operate. Therefore, by increasing the difference between the boost setting voltage value V1 and the step-down setting voltage value V2, it is possible to set so that the battery voltage region where both the booster circuit 42 and the step-down circuit 44 do not operate is widened. As a result, even when the battery voltage VB fluctuates and when the circuit current changes due to load fluctuations, the step-up and step-down exclusive operations can be performed, and control stability and transient response can be ensured.

In the internal power supply circuit 15, the booster circuit 42 is connected in parallel to the power supply wiring VL <b> 1 that is connected to the step-down circuit 44 and supplies the battery voltage VB.
On the power supply line VL1, the diode 41 is connected to the connection point P1 between the power supply line VL2 and the power supply line VL1 for inputting the battery voltage VB to the booster circuit 42, and the power supply line VL3 and the power supply for outputting the battery voltage VB from the booster circuit 42. Provided between the connection point P2 and the wiring VL1, and prevents current from flowing from the connection point P2 toward the connection point P1.

The diode 43 is provided between the connection point P2 and the booster circuit 42 on the power supply wiring VL3, and prevents current from flowing from the connection point P2 toward the booster circuit 42.
As a result, even when the voltage at the connection point P2 becomes larger than the voltage at the connection point P1 due to the boosting circuit 42 performing the boosting operation, the connection is made from the connection point P2 via the power supply line VL1. There is no current flowing toward the point P1, and no current flows from the connection point P2 toward the connection point P1 via the power supply lines VL2 and Vl3.

  For this reason, when the booster circuit 42 is performing the boosting operation, the battery voltage VB is supplied to the step-down circuit 44 via the power supply lines VL2 and VL3. On the other hand, when the booster circuit 42 is not performing the boosting operation, the battery voltage VB is supplied to the step-down circuit 44 through the power supply wiring VL1.

The reason why the booster circuit 42 performs the boosting operation is to prevent the microcomputer 11 from resetting due to a temporary drop in the battery voltage VB when the engine is started.
Therefore, the current flowing in the booster circuit 42 through the power supply wirings VL2 and VL3 may be an amount that can supply power that allows the microcomputer 11 to operate. For this reason, the rating of the components (for example, the boosting coil, the boosting diode, etc.) constituting the booster circuit 42 can be made smaller than usual.

  The booster circuit 42 is configured to perform the boosting operation only when the battery voltage VB is equal to or lower than the boosting set voltage value V1 and the key position is the starter position.

  As a result, when the battery voltage VB is reduced except when the engine is started, the boosting operation is not performed unnecessarily, and the power consumption of the internal power supply circuit 15 can be suppressed.

  In the embodiment described above, the internal power supply circuit 15 is the power supply voltage control device in the present invention, the battery voltage VB is the power supply voltage in the present invention, the power supply wiring VL1 is the first power supply wiring in the present invention, and the power supply wiring VL2 is the first power supply wiring in the present invention. The two power supply wirings, the power supply wiring VL3 are the third power supply wirings in the present invention, the diode 41 is the first backflow prevention unit in the present invention, and the diode 43 is the second backflow prevention unit in the present invention.

As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, As long as it belongs to the technical scope of this invention, a various form can be taken.
For example, in the above-described embodiment, the booster circuit 42 is connected in parallel to the power supply wiring VL1 that inputs the battery voltage VB to the step-down circuit 44, but the power supply wiring that outputs the battery voltage VB from the step-down circuit 44 is shown. Alternatively, the booster circuit 42 may be connected in parallel.

  In the above embodiment, the booster circuit 42 performs the boost operation when the key position of the ignition key cylinder is the starter position. However, the booster circuit 42 performs the boost operation when the starter is operated. For example, the booster circuit may perform the boosting operation when the start button is operated while the brake is depressed in the smart entry system.

  DESCRIPTION OF SYMBOLS 1 ... ECU, 4 ... Battery, 11 ... Microcomputer, 15 ... Internal power supply circuit, 42 ... Booster circuit, 44 ... Step-down circuit

Claims (2)

A power supply voltage control device (15) for controlling a power supply voltage of a power supply (4) for supplying power to equipment mounted on a vehicle,
A booster circuit (42) for performing a boosting operation for raising the power supply voltage to the boosting set voltage value when the power supply voltage is equal to or lower than a preset boosting set voltage value;
A step-down circuit (44) for performing a step-down operation for dropping the power supply voltage to the step-down set voltage value when the power supply voltage is equal to or higher than a preset step-down set voltage value;
The boost setting voltage value is set to be smaller than the step-down setting voltage value,
The booster circuit is configured not to execute the boosting operation when the power supply voltage exceeds the boosting set voltage value;
The step-down circuit is configured not to perform the step-down operation when the power supply voltage is less than the step-down setting voltage value ,
The booster circuit includes:
The boosting operation is performed only when the power supply voltage is equal to or lower than a preset boosting voltage value and when a starter for starting the vehicle engine is activated. Power supply voltage control device. The booster circuit is connected in parallel to a first power supply line (VL1) that is connected to the step-down circuit and supplies the power supply voltage.
On the first power supply line, a first connection point (P1) between the second power supply line (VL2) for inputting the power supply voltage to the booster circuit and the first power supply line, and the power supply voltage from the booster circuit. It is provided between the third power supply wiring (VL3) to be output and the second connection point (P2) between the first power supply wiring, and current flows from the second connection point toward the first connection point. A first backflow blocking portion (41) for blocking;
On the third power supply wiring, a second backflow prevention unit (43) is provided between the second connection point and the booster circuit, and prevents current from flowing from the second connection point to the booster circuit. The power supply voltage control device according to claim 1, further comprising:

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