JP2015159642A - Power supply circuit for vehicle and control method of power supply circuit for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method of a power supply circuit for vehicle, in which voltage supply to the internal circuit of an electronic controller is not interrupted.SOLUTION: A control method of a power supply circuit for vehicle including a switching regulator for stepping down the input voltage to an electronic controller, and a series regulator connected in series with the switching regulator and stepping down the voltage that is stepped down by the switching regulator includes a determination step for determining whether or not the electronic controller is in sleep state, a determination step for determining whether or not the input voltage goes above a threshold, and a switching step for switching the switching regulator from stop state to operation state when the electronic controller is in sleep state, and the input voltage goes above a threshold.

Description

  The present invention relates to a vehicle power supply circuit and a control method for a vehicle power supply circuit.

  Conventionally, the input voltage from an external power supply is stepped down by a switching regulator, further stepped down by a series regulator connected in series with the switching regulator, and a desired constant voltage is generated to supply voltage to each circuit. Power supply circuits are known.

  A power supply circuit that can ensure system safety by stopping driving of a series regulator by a control circuit when an input voltage exceeds a predetermined voltage value is disclosed (for example, see Patent Document 1).

  In addition, a power supply circuit that can reduce the burden on the on-vehicle battery by controlling the operation start or operation stop of the switching regulator according to the load current is disclosed (for example, see Patent Document 2).

JP2013-156874A Japanese Patent Laid-Open No. 05-038138

  In order to improve engine startability at an extremely low temperature (for example, −40 ° C.), two batteries may be connected in series to intentionally increase the input voltage to the electronic control unit (for example, 24 V).

  However, since the switching regulator does not perform a switching operation when the engine is started, in this case, a high voltage is input to the series regulator.

  If the driving of the series regulator is stopped to protect the circuit, the voltage supply to the internal circuit (for example, a microcomputer) of the electronic control unit is cut off, making it difficult to start the engine.

  Accordingly, an object of the present invention is to provide a control method for a vehicle power supply circuit in which voltage supply to an internal circuit of an electronic control device is not interrupted.

In order to achieve the above object, according to one aspect,
A control method for a vehicle power supply circuit comprising: a switching regulator that steps down an input voltage to an electronic control device; and a series regulator that is connected in series with the switching regulator and steps down a voltage stepped down by the switching regulator. And
A determination step of determining whether or not the electronic control device is in a sleep state;
A determination step of determining whether or not the input voltage is greater than or equal to a threshold;
A switching step of switching the switching regulator from a stopped state to an operating state when the electronic control unit is in a sleep state and the input voltage is equal to or higher than the threshold;
A control method for a vehicle power supply circuit is provided.

  According to one aspect, it is possible to provide a control method for a vehicle power supply circuit in which voltage supply to an internal circuit of the electronic control device is not interrupted.

It is a figure which shows an example of a structure of the power supply circuit which concerns on this embodiment. It is a figure which shows an example of operation | movement of the power supply circuit which concerns on this embodiment. It is a figure which shows an example of operation | movement of the power supply circuit which concerns on this embodiment.

  Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant description may be omitted.

  The “IG-switch (ignition switch)” refers to a switch for starting or stopping the engine of the vehicle.

  The “switching regulator stop state” means a state where the switching element included in the switching regulator is not switched and the switching element is always turned on. This means that the switching element included in the regulator is in a switching operation.

<Configuration of power supply circuit for vehicle>
FIG. 1 shows an example of a schematic configuration of a power supply circuit 100 according to the present embodiment.

  The power supply circuit 100 includes a battery 1, an IG-switch 2, an in-vehicle ECU (electronic control unit) 3, and the like. The vehicle-mounted ECU 3 includes a filter circuit 4, a switching regulator 5, a series regulator 6, a power supply control circuit 7, a voltage monitor circuit 8, an input circuit 9, a microcomputer (microcomputer) 10, and the like. A node between the output side of the switching regulator 5 and the input side of the series regulator 6 is referred to as a node A. A node on the output side of the series regulator 6 is a node B.

  The status signal 11 is a signal indicating whether the in-vehicle ECU 3 is in a standby (sleep) state or the in-vehicle ECU 3 is in a normal (wake-up) state, and is a signal output from the microcomputer 10.

  The battery 1 is a known secondary battery (storage battery) mounted in an engine room, a trunk, or the like, and examples thereof include a 12V lead battery, a nickel metal hydride battery, and a lithium ion battery. One battery 1 is usually mounted on a vehicle.

  The IG-switch 2 is a switch that is disposed in the vicinity of the driver's seat of the vehicle and activates the vehicle engine or stops the vehicle engine. By turning on the switch position of the IG-switch 2 from off, the vehicle is powered on.

  The in-vehicle ECU 3 is an ECU that performs state transition between the standby state and the normal state in conjunction with the IG-switch 2. For example, when the IG-switch 2 is on, the in-vehicle ECU 3 is in a normal state.

  The filter circuit 4 is disposed on the input side of the switching regulator 5 and absorbs noise in the power supply line. Since the filter circuit 4 is disposed close to the battery 1, it is preferable that the filter circuit 4 is configured by a circuit having a high withstand voltage (for example, a withstand voltage of 35 V). For example, a π-type filter circuit composed of a capacitor, a coil, or the like may be used, or a smoothing circuit composed of an aluminum electrolytic capacitor or the like may be used.

  The switching regulator 5 is a power supply circuit that includes a switching element (for example, MOSFET), a coil, a diode, and the like, and steps down and outputs an input voltage to the in-vehicle ECU 3. The voltage output from the switching regulator 5 (node A voltage) is stepped down so as not to exceed the threshold.

  For example, when the in-vehicle ECU 3 is in a normal state, the switching regulator 5 is in an operating state. The switching regulator 5 steps down the input voltage (for example, 12V) and outputs it by switching the switching element (for example, a frequency of 400 kHz). In this case, the voltage of the node A is, for example, 6.0V.

  Further, when the in-vehicle ECU 3 is in a standby state and the input voltage (for example, 12 V) is smaller than the threshold value, the switching regulator 5 is in a stopped state. The switching regulator 5 outputs the input voltage (for example, 12V) as it is by always turning on the switching element without switching the switching element. In this case, the voltage of the node A is, for example, 12V.

  Further, when the in-vehicle ECU 3 is in a standby state and the input voltage (for example, 24V) is equal to or higher than a threshold value, the switching regulator 5 is in an operating state. The switching regulator 5 steps down and outputs an input voltage (for example, 24 V) by switching the switching element. In this case, the voltage of the node A is, for example, 6.0V.

  Since the switching operation of the switching element is controlled according to the state of the in-vehicle ECU 3 and the magnitude of the input voltage, the voltage at the node A can be kept below the threshold value.

  The threshold value varies depending on the specification, configuration, etc. of the power supply circuit, and the value is not particularly limited. In the power supply circuit 100, the threshold may be at least equal to or higher than the voltage of the battery 1.

  The series regulator 6 is a power supply circuit that is connected in series with the switching regulator 5 and that steps down and outputs the voltage at the node A (for example, 6.0 V, 12 V). The voltage output from the series regulator 6 (node B voltage) is step-down controlled so as to be constant (at least 5.0 V or higher). 5.0 V is a minimum voltage required to continue various processes (for example, memory retention in the ECU) performed in each circuit in the microcomputer 10 and the in-vehicle ECU 3. The voltage to be stepped down is adjusted in accordance with the fluctuation of the voltage output from the switching regulator 5 (node A voltage).

  For example, when the in-vehicle ECU 3 is in a normal state, the series regulator 6 further reduces the voltage of the node A (for example, 6.0 V) and outputs it. In this case, the voltage to be stepped down is, for example, 5.0V.

  Further, when the in-vehicle ECU 3 is in a standby state and the input voltage (for example, 12V) is smaller than the threshold value, the series regulator 6 steps down the voltage of the node A (for example, 12V) and outputs it. In this case, the voltage to be stepped down is, for example, 5.0V.

  When the in-vehicle ECU 3 is in a standby state and the input voltage (for example, 24V) is equal to or higher than the threshold value, the series regulator 6 further reduces the voltage of the node A (for example, 6.0V) and outputs the voltage. . In this case, the voltage to be stepped down is, for example, 5.0V.

  The series regulator 6 can generate a regulated voltage (for example, ± 35 mV) more accurately than the switching regulator 5. For this reason, each circuit in the microcomputer 10 and the vehicle-mounted ECU 3 can perform a stable operation by using the voltage of the node B.

  The power supply control circuit 7 determines whether the in-vehicle ECU 3 is in a standby state or the in-vehicle ECU 3 is in a normal state based on ON / OFF of the IG-switch 2 (output from the input circuit 9), the status signal 11, and the like. judge. Furthermore, the power supply control circuit 7 controls the switching operation of the switching regulator 5 based on the state of the in-vehicle ECU 3 and the input voltage (notification from the voltage monitor circuit 8).

  For example, if the IG-switch 2 is turned on or the status signal 11 of the microcomputer 10 is a signal indicating that the in-vehicle ECU 3 is in a normal state, the power supply control circuit 7 sets the switching regulator 5 in an operating state. That is, the switching element included in the switching regulator 5 is switched.

  For example, if the IG-switch 2 is off and the status signal 11 of the microcomputer 10 is a signal indicating that the in-vehicle ECU 3 is in a standby state, and the input voltage is smaller than a threshold value, the power supply control circuit 7 5 is set to the stop state. That is, the switching element included in the switching regulator 5 is not switched and the switching element is always turned on. By always turning on the switching element, it is possible to reduce current consumption in the power supply circuit 100.

  For example, if the IG-switch 2 is off and the status signal 11 of the microcomputer 10 is a signal indicating that the in-vehicle ECU 3 is in a standby state, and if the input voltage is equal to or higher than a threshold value, the power supply control circuit 7 The regulator 5 is put into an operating state. As a result, when the in-vehicle ECU 3 is in a standby state, even if an unexpectedly (or intentionally) high voltage is input, the voltage is appropriately stepped down and the voltage at the node A can be kept below the threshold value. . Therefore, the series regulator 6 is always operated (without being stopped), and a stable constant voltage can be supplied to each circuit in the microcomputer 10 and the in-vehicle ECU 3.

  The voltage monitor circuit 8 includes a comparator and the like, detects an input voltage to the switching regulator 5, and notifies the detection result to the power supply control circuit 7. For example, the voltage monitor circuit 8 notifies the power supply control circuit 7 of a detection result that the input voltage is equal to or higher than a threshold (for example, 18 V or higher).

  The voltage monitor circuit 8 can detect the input voltage even when the IG-switch 2 is off. When the IG-switch 2 is off, the voltage of the battery 1 is input to the filter circuit 4 and the switching regulator 5 via the diode (upper side of the drawing), and further, the voltage monitor circuit via the diode (upper side of the drawing). This is because it is input to 8. In this case, the path from the IG-switch 2 to the filter circuit 4 via the diode (lower side of the drawing), the path from the IG-switch 2 to the voltage monitor circuit 8 via the diode (lower side of the drawing), and IG− The path from the switch 2 to the input circuit 9 is blocked.

  The input circuit 9 converts a signal (for example, a 12V system signal) indicating whether the IG-switch 2 is on or the IG-switch 2 is off, and converts the signal (for example, a 5V system signal). Is output to the power supply control circuit 7 and the microcomputer 10. For example, the input circuit 9 outputs 5.0 V to the power supply control circuit 7 and the microcomputer 10 when the IG-switch 2 is on, and to the power supply control circuit 7 and the microcomputer 10 when the IG-switch 2 is off. Outputs 0V.

  The microcomputer 10 generates a status signal 11 based on a signal input from the input circuit 9 and outputs the status signal 11 to the power supply control circuit 7. For example, when the IG-switch 2 is on, the microcomputer 10 outputs a status signal 11 indicating that the in-vehicle ECU 3 is in a normal state to the power supply control circuit 7. Further, the microcomputer 10 executes various controls of the in-vehicle ECU 3 by being supplied with the voltage (the voltage at the node B) output from the series regulator 6. The microcomputer 10 controls driving of the engine, and starts the engine when the IG-switch 2 is on, and stops the engine when the IG-switch 2 is off. When the IG-switch 2 is off, the microcomputer 10 is in a low current consumption mode.

<Flowchart of power supply circuit>
FIG. 2 is a flowchart illustrating an example of a method for controlling the switching regulator 5 when the in-vehicle ECU 3 is in a normal state or a standby state. The flowchart of FIG. 2 is executed by the power supply control circuit 7.

  In step S10, the power supply control circuit 7 monitors on / off of the IG-switch 2 and determines whether the IG-switch 2 is off. When the IG-switch 2 is off (YES), the power supply control circuit 7 performs the process of step S20. When the IG-switch 2 is on (NO), the power supply control circuit 7 performs the process of step S40.

  In step S20, the power supply control circuit 7 monitors the status signal 11 and determines whether or not the in-vehicle ECU 3 is in a standby state. When the in-vehicle ECU 3 is in a standby state (YES), the power supply control circuit 7 performs the process of step S30. When the vehicle-mounted ECU 3 is in a normal state (NO), the power supply control circuit 7 performs the process of step S40.

  In step S30, the power supply control circuit 7 determines that the in-vehicle ECU 3 is in a standby state (when the IG-switch 2 is off and the status signal 11 indicates that the in-vehicle ECU 3 is in a standby state), the switching regulator 5 is switched on. Set to the stop state.

  In step S40, the power supply control circuit 7 determines that the in-vehicle ECU 3 is in the normal state (when the IG-switch 2 is on or the status signal 11 indicates that the in-vehicle ECU 3 is in the normal state), the switching regulator 5 is switched on. Activated.

  After the processes in step S30 and step S40, the power supply control circuit 7 performs the process of step S10 again (return).

  According to the above-described processing, when the on-vehicle ECU 3 determines that the in-vehicle ECU 3 is in the normal state based on the on / off state of the IG-switch 2 and the status signal 11, the power supply control circuit 7 sets the switching regulator 5 in the operating state, The voltage can be stepped down to a desired voltage.

  FIG. 3 is a flowchart showing an example of a switching control method of the switching regulator 5 based on the input voltage when the in-vehicle ECU 3 is in a standby state. The flowchart of FIG. 3 is executed by the power supply control circuit 7.

  In step S210, the power supply control circuit 7 determines whether or not the in-vehicle ECU 3 is in a standby state. When the in-vehicle ECU 3 is in a standby state (YES), the power supply control circuit 7 performs the process of step S220. When the in-vehicle ECU 3 is not in the standby state (NO), the power supply control circuit 7 performs the process of step S210 again (return).

  In step S <b> 220, the power supply control circuit 7 determines whether or not the voltage monitor circuit 8 detects a voltage that is equal to or higher than a threshold (for example, 18 V or higher) as the input voltage. When a voltage equal to or higher than the threshold is detected as the input voltage (YES), the power supply control circuit 7 performs the process of step S230. When a voltage smaller than the threshold is detected as the input voltage (NO), the power supply control circuit 7 performs the process of step S210 again (return).

  In step S230, the power supply control circuit 7 switches the switching regulator 5 from the stop state to the operation state based on the determination that the in-vehicle ECU 3 is in the sleep state and a voltage equal to or higher than the threshold is detected as the input voltage.

  According to the above-described processing, when the on-vehicle ECU 3 is in a standby state and a voltage equal to or higher than the threshold value is detected as the input voltage, the power supply control circuit 7 sets the switching regulator 5 in the operating state and sets the input voltage as desired. The voltage can be stepped down to

  According to the control method of the power supply circuit according to the present embodiment, even if a high voltage is input when the in-vehicle ECU 3 is in a standby state, the voltage supply to each circuit or the like in the in-vehicle ECU 3 is not cut off. Further, it becomes possible to easily start the engine at an extremely low temperature.

  As mentioned above, although the form for implementing this invention was explained in full detail, this invention is not limited to this specific embodiment, In the range of the summary of this invention described in the claim, various Can be modified or changed.

  For example, in the above-described embodiment, as an example of the switching element, a MOSFET that is a semiconductor element that performs an on / off operation is described. However, the switching element may be, for example, a voltage-controlled power element using an insulated gate such as IGBT or MOSFET, or a bipolar transistor.

2 IG-switch 3 On-vehicle ECU (an example of an electronic control unit)
5 Switching regulator 6 Series regulator 7 Power supply control circuit (control circuit)
100 Power supply circuit

Claims (8)

A control method for a vehicle power supply circuit comprising: a switching regulator that steps down an input voltage to an electronic control device; and a series regulator that is connected in series with the switching regulator and steps down a voltage stepped down by the switching regulator. And
A determination step of determining whether or not the electronic control device is in a sleep state;
A determination step of determining whether or not the input voltage is greater than or equal to a threshold;
And a switching step of switching the switching regulator from a stopped state to an operating state when the electronic control device is in a sleep state and the input voltage is equal to or higher than the threshold value.   2. The method of controlling a vehicle power supply circuit according to claim 1, wherein the voltage of a node between the output side of the switching regulator and the input side of the series regulator is stepped down so as not to exceed the threshold value.   The vehicle power supply circuit control method according to any one of claims 1 and 2, wherein a voltage at a node on an output side of the series regulator is controlled to be constant.   4. The vehicle power supply circuit according to claim 1, wherein the electronic control device determines whether or not the electronic control device is in a sleep state based on on / off of an IG-switch and a status signal of the microcomputer. 5. Control method. A switching regulator that steps down the input voltage to the electronic control unit;
A series regulator connected in series with the switching regulator to step down the voltage stepped down by the switching regulator;
A control circuit for controlling the switching operation of the switching regulator, and a vehicle power supply circuit comprising:
The control circuit includes:
A vehicle power supply circuit that switches the switching regulator from a stopped state to an activated state when the electronic control unit is in a sleep state and the input voltage is detected to be greater than or equal to a threshold value. The control circuit includes:
6. The vehicle power supply circuit according to claim 5, wherein a switching operation of the switching regulator is controlled so that a voltage of a node between the output side of the switching regulator and the input side of the series regulator does not exceed the threshold value. . The control circuit includes:
The vehicle power supply circuit according to any one of claims 5 and 6, wherein a voltage at a node on an output side of the series regulator is made constant. The control circuit includes:
The vehicle power supply circuit according to any one of claims 5 to 7, wherein whether or not the electronic control device is in a sleep state is determined based on an on / off state of an IG-switch and a status signal of a microcomputer.

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