JP7149128B2 - vehicle power supply - Google Patents

Description

The present invention relates to a vehicle power supply device mounted on a vehicle.

A vehicle power supply device mounted on a vehicle is provided with a storage body such as a lead battery or a lithium ion battery, and is provided with a generator motor such as a motor generator or an ISG (Integrated Starter Generator) (Patent Document 1 or 2).

JP-A-10-23604 JP-A-2008-29071

In order to charge the power storage body without impairing the energy efficiency of the vehicle, it is desirable to regeneratively generate power by the generator motor when the vehicle decelerates. However, when the state of charge SOC of the power storage body is low, it is required to control the generator motor to the power generation state without waiting for the opportunity to decelerate the vehicle. In other words, it is required to control the generator-motor to generate power while rotating the generator-motor by the engine.

By the way, driving the generator-motor in the generating state by the engine causes an increase in the engine load, so there is a possibility that the engine may stall depending on the engine speed, the fuel supply situation, the ignition situation, and the like. Therefore, it is required to prevent engine stall when the generator motor is driven by the engine.

An object of the present invention is to prevent engine stall.

A vehicle power supply device according to the present invention is a vehicle power supply device mounted on a vehicle, and includes a first power supply system including a first power storage body and an electric load connected to the first power storage body; and a second power storage unit connected to the generator motor; and a second power system provided between the first power system and the second power system, wherein the first an energization path that connects a power storage body and the second power storage body in parallel; an ON state that is provided in the energization path and connects the first power supply system and the second power supply system; an OFF state for disconnecting from a second power supply system; an ON state provided in the second power supply system for connecting the generator motor and the second power storage unit; and the generator motor. a second switch that is controlled to be in an off state for disconnecting from the second power storage body; and the generator motor is driven by the engine , the first switch is controlled to be in an on state, and the second switch is in an off state. a generator-motor control unit for executing engine power generation control for controlling the generator-motor to a power generation state under a controlled state, wherein the generator-motor control unit controls the state in which the engine power generation control is executed; When the rotation speed of the engine falls below the auxiliary start threshold, the switch control unit switches the generator motor from the power generation state to the power running state and controls the second switch so that the engine power generation control is executed. Under the above conditions, the second switch is switched from the off state to the on state when the rotation speed of the engine is below the auxiliary start threshold.
A vehicle power supply device according to the present invention is a vehicle power supply device mounted on a vehicle, and includes a first power supply system including a first power storage body and an electric load connected to the first power storage body; and a second power storage unit connected to the generator motor; and a second power system provided between the first power system and the second power system, wherein the first An energization path that connects a power storage body and the second power storage body in parallel, and a generator motor that executes engine power generation control to control the generator motor to a power generation state while the generator motor is driven by the engine. and a control unit, wherein the generator-motor control unit causes the generator-motor to power run from a power generation state when the rotational speed of the engine falls below an auxiliary start threshold under a state in which the engine power generation control is executed. state, and after switching the generator motor from the power generation state to the power running state, if the rotation speed of the engine exceeds an auxiliary end threshold that is higher than the auxiliary start threshold, the generator motor is switched from the power running state to the power generation state. the generator-motor control unit increases the power running torque of the generator-motor at a first rate of change when the rotation speed of the engine falls below the auxiliary start threshold and the generator-motor is switched from the power generation state to the power running state; When the rotation speed of the engine exceeds the auxiliary end threshold and the generator motor is switched from the power running state to the power generation state, the power running torque of the generator motor is decreased at a second change speed slower than the first change speed.

According to the present invention, the generator motor is switched from the power generation state to the power running state when the rotation speed of the engine falls below the auxiliary start threshold under the state where the engine power generation control is executed. As a result, the rotation speed of the engine can be increased, and engine stall can be prevented.

1 is a schematic diagram showing a configuration example of a vehicle equipped with a vehicle power supply device according to an embodiment of the present invention; FIG. 1 is a circuit diagram simply showing an example of a power supply circuit; FIG. FIG. 4 is a diagram showing an example of a current supply state when the starter generator is controlled to a combustion power generation state; FIG. 4 is a diagram showing an example of a current supply state when the starter generator is controlled to a power generation halt state; FIG. 4 is a diagram showing an example of a current supply state when the starter generator is controlled to a regenerative power generation state; FIG. 4 is a diagram showing an example of a current supply state when the starter generator is controlled to a power running state; FIG. 4 is a diagram showing an example of a current supply state when the starter generator is controlled to a power running state; FIG. 4 is a diagram showing an example of a current supply situation in engine initial start control; FIG. 4 is a diagram showing an example of a current supply situation in lead battery supplementary charging control; 4 is a timing chart showing an example of changes in engine speed, ISG torque, etc. when engine stall prevention control 1 is executed; (A) and (B) are diagrams showing an example of a current supply state when engine stall prevention control 1 is executed. 4 is a flowchart showing an example of an execution procedure of engine stall prevention control 1; 4 is a timing chart showing an example of changes in engine speed, ISG torque, etc. when engine stall prevention control 2 is executed; (A) and (B) are diagrams showing an example of a current supply situation when engine stall prevention control 2 is executed. 4 is a flowchart showing an example of an execution procedure of engine stall prevention control 2;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Vehicle configuration]
FIG. 1 is a schematic diagram showing a configuration example of a vehicle 11 equipped with a vehicle power supply device 10 according to an embodiment of the present invention. As shown in FIG. 1, a vehicle 11 is equipped with a power unit 13 using an engine 12 as a power source. A starter generator (generator motor) 16 is connected to a crankshaft 14 of the engine 12 via a belt mechanism 15 . A transmission mechanism 18 is connected to the engine 12 via a torque converter 17, and wheels 20 are connected to the transmission mechanism 18 via a differential mechanism 19 and the like.

A starter generator 16 connected to the engine 12 is a so-called ISG (Integrated Starter Generator) that functions as a generator and an electric motor. The starter generator 16 functions not only as a generator driven by the crankshaft 14 but also as an electric motor that drives the crankshaft 14 . For example, when restarting the engine 12 in idling stop control, or when assisting the engine 12 during starting or accelerating, the starter generator 16 is controlled to a power running state and the starter generator 16 functions as an electric motor.

The starter generator 16 has a stator 30 with stator coils and a rotor 31 with field coils. The starter generator 16 is also provided with an ISG controller 32 comprising an inverter, a regulator, a microcomputer, various sensors, etc., in order to control the energization of the stator coil and field coils. By controlling the energized states of the field coils and stator coils with the ISG controller 32, the power generation voltage, power generation torque, power running torque, etc. of the starter generator 16 can be controlled.

The power unit 13 is also provided with a starter motor (electrical load) 33 that starts and rotates the engine 12 . The pinion 34 of the starter motor 33 is movable between a projecting position where it meshes with the ring gear 35 of the torque converter 17 and a retracted position where it disengages from the ring gear 35 . As will be described later, when the starter button 36 is pushed by the passenger, the starter relay 37 that controls the energization of the starter motor 33 is turned on. As a result, the starter motor 33 is energized via the starter relay 37, and the pinion 34 of the starter motor 33 moves to the projecting position and rotates. In order to control the starter motor 33 via the starter relay 37, the vehicle 11 is provided with an engine controller 38 comprising a microcomputer or the like. The engine controller 38 not only controls the starter relay 37, but also controls engine accessories 39 such as a throttle valve, injectors and an ignition device.

As described above, the illustrated vehicle 11 is provided with the starter generator 16 and the starter motor 33 as electric motors for starting and rotating the engine 12 . When the engine 12 is restarted by the idling stop control, that is, when the stop condition is satisfied while the engine is running, the engine 12 is stopped, and when the start condition is satisfied while the engine is stopped, the engine 12 is restarted. , the starter generator 16 is used to start the engine 12 . On the other hand, when the control system of the vehicle 11 is started and the engine 12 is started first, that is, when the engine 12 is started by the passenger's operation of the starter button, the starter motor 33 is used to start the engine 12. .

[Power supply circuit]
The power supply circuit 50 included in the vehicle power supply device 10 will be described. FIG. 2 is a circuit diagram simply showing an example of the power supply circuit 50. As shown in FIG. As shown in FIG. 2, the power supply circuit 50 includes a lead battery (first power storage unit) 51 electrically connected to the starter generator 16 and a lithium ion battery electrically connected to the starter generator 16 in parallel. (second power storage body) 52; In order to discharge the lithium ion battery 52 positively, the terminal voltage of the lithium ion battery 52 is designed to be higher than the terminal voltage of the lead battery 51 . Moreover, the internal resistance of the lithium ion battery 52 is designed to be smaller than the internal resistance of the lead battery 51 in order to actively charge and discharge the lithium ion battery 52 .

A positive line 53 is connected to the positive terminal 16a of the starter generator 16, a positive line 54 is connected to the positive terminal 52a of the lithium ion battery 52, and a positive line 55 is connected to the positive terminal 51a of the lead battery 51. 56 are connected. These positive lines 53 , 54 , 56 are connected to each other via a connection point 57 . A negative line 58 is connected to the negative terminal 16b of the starter generator 16, a negative line 59 is connected to the negative terminal 52b of the lithium ion battery 52, and a negative line 60 is connected to the negative terminal 51b of the lead battery 51. be. These negative lines 58 , 59 , 60 are connected to each other via a reference potential point 61 .

As shown in FIG. 1 , a positive electrode line 62 is connected to the positive electrode line 55 of the lead battery 51 . An electric device group 64 including electric devices (electric loads) 63 such as various actuators and various controllers is connected to the positive electrode line 62 . A battery sensor 65 is provided on the negative electrode line 60 of the lead battery 51 . The battery sensor 65 has a function of detecting the charge/discharge status of the lead battery 51 . The charge/discharge status of the lead battery 51 includes, for example, charge current, discharge current, terminal voltage, state of charge SOC, and the like of the lead battery 51 .

Further, the power supply circuit 50 is provided with a first power supply system 71 consisting of the lead battery 51, the starter motor 33 and the electrical equipment 63, and is provided with a second power supply system 72 consisting of the lithium ion battery 52 and the starter generator 16. ing. The lead battery 51 and the lithium ion battery 52 are connected in parallel with each other via a positive electrode line (energization path) 56 provided between the first power supply system 71 and the second power supply system 72 . The positive electrode line 56 is provided with a power fuse 73 that is blown by an excessive current, and a first switch SW1 that is controlled to be turned on and off. A positive electrode line 54 of the lithium ion battery 52 is provided with a second switch SW2 that is controlled to be turned on and off.

By controlling the switch SW1 to the ON state, the first power system 71 and the second power system 72 can be connected to each other. The two power supply systems 72 can be separated from each other. By controlling the switch SW2 to the ON state, the starter generator 16 and the lithium ion battery 52 can be connected to each other. can be separated from each other.

These switches SW1 and SW2 may be switches composed of semiconductor elements such as MOSFETs, or may be switches that mechanically open and close contacts using electromagnetic force or the like. The ON state of the switches SW1 and SW2 means a energized state or conductive state in which they are electrically connected. means state. The switches SW1 and SW2 are also called relays or contactors.

As shown in FIG. 1, the power supply circuit 50 is provided with a battery module 74 . This battery module 74 has a lithium ion battery 52 and switches SW1 and SW2. Also, the battery module 74 has a battery controller 75 comprising a microcomputer, various sensors, and the like. The battery controller 75 has a function of monitoring the state of charge SOC, charging current, discharging current, terminal voltage, cell temperature, internal resistance, etc. of the lithium ion battery 52, and a function of controlling the switches SW1 and SW2. The state of charge SOC (State Of Charge) is the ratio of the amount of charge to the design capacity of the battery.

[Control system]
As shown in FIG. 1, the vehicle power supply device 10 has a main controller 80 such as a microcomputer for controlling the power unit 13, the power supply circuit 50, and the like in cooperation with each other. The main controller 80 controls an engine control unit 81 that controls the engine 12, an ISG control unit (generator motor control unit) 82 that controls the starter generator 16, a first switch control unit 83 that controls the switch SW1, and a switch SW2. It has a second switch control section (switch control section) 84 that The main controller 80 also has a starter control section 85 that controls the starter motor 33, an idling control section 86 that executes idling stop control, which will be described later, and an assist control section 87 that executes motor assist control, which will be described later.

The main controller 80 and the controllers 32, 38, 42, 75 described above are connected to each other so as to be communicable via an in-vehicle network 88 such as CAN or LIN. The main controller 80 controls the power unit 13, power supply circuit 50, etc. based on information from various controllers and various sensors. The main controller 80 controls the starter generator 16 via the ISG controller 32 and controls the switches SW1 and SW2 via the battery controller 75 . The main controller 80 also controls the engine 12 and the starter motor 33 via the engine controller 38 . An engine speed sensor 89 for detecting the engine speed Ne is also connected to the engine controller 38 . The engine rotation speed Ne is the rotation speed of the engine 12 , that is, the rotation speed of the crankshaft 14 provided in the engine 12 .

[Starter generator power generation control]
Next, power generation control of the starter generator 16 by the main controller 80 will be described. The ISG control unit 82 of the main controller 80 outputs a control signal to the ISG controller 32 to control the starter generator 16 to the power generation state or the power running state. For example, when the state of charge SOC of the lithium ion battery 52 decreases, the ISG control unit 82 increases the power generation voltage of the starter generator 16 and controls the combustion power generation state. The power generation voltage of the generator 16 is lowered to control the power generation halt state. In addition, in each drawing after FIG. 3 which will be described later, “ISG” means the starter generator 16 .

FIG. 3 is a diagram showing an example of the current supply state when the starter generator 16 is controlled to the combustion power generation state. The combustion power generation state of the starter generator 16 is a state in which the starter generator 16 generates power with engine power, that is, a state in which the starter generator 16 generates power by burning fuel in the engine. For example, when the state of charge SOC of the lithium ion battery 52 is below a predetermined lower limit, the starter generator 16 is caused to generate power by the engine power in order to charge the lithium ion battery 52 and increase the state of charge SOC. Thus, when the starter generator 16 is controlled to the combustion power generation state, the generated voltage of the starter generator 16 is increased to exceed the terminal voltages of the lead battery 51 and the lithium ion battery 52 . As a result, as indicated by black arrows in FIG. is slowly charged.

FIG. 4 is a diagram showing an example of the current supply state when the starter generator 16 is controlled to the power generation suspension state. For example, when the state of charge SOC of the lithium ion battery 52 exceeds a predetermined upper limit value, the power generation of the starter generator 16 using engine power is suspended in order to actively discharge the lithium ion battery 52 . In this way, when the starter generator 16 is controlled to the power generation suspended state, the generated voltage of the starter generator 16 is lowered to be lower than the terminal voltages of the lead battery 51 and the lithium ion battery 52 . As a result, current is supplied from the lithium-ion battery 52 to the electrical equipment group 64, as indicated by the black arrow in FIG. can be done. It should be noted that the voltage generated by the starter generator 16 in the power generation suspension state may be any voltage that discharges the lithium ion battery 52 . For example, the generated voltage of the starter generator 16 may be controlled to 0V, or the generated voltage of the starter generator 16 may be controlled to be higher than 0V.

As described above, the ISG control unit 82 of the main controller 80 controls the starter generator 16 to the combustion power generation state or the power generation suspension state based on the state of charge SOC. It is required to improve the performance. Therefore, when the vehicle decelerates, the power generation voltage of the starter generator 16 is raised, and the starter generator 16 is controlled to the regenerative power generation state. As a result, since the power generated by the starter generator 16 can be increased, the kinetic energy can be positively converted into electrical energy and recovered, and the energy efficiency of the vehicle 11 can be enhanced to improve fuel efficiency. can. Whether or not to execute such regenerative power generation is determined based on the operating conditions of the accelerator pedal and the brake pedal. That is, the starter generator 16 is controlled to the regenerative power generation state during deceleration when the accelerator pedal is released or when the brake pedal is depressed.

Here, FIG. 5 is a diagram showing an example of the current supply state when the starter generator 16 is controlled to the regenerative power generation state. When the starter generator 16 is controlled to the regenerative power generation state, the power generation voltage of the starter generator 16 is raised above that in the combustion power generation state described above. As a result, a large current is supplied from the starter generator 16 to the lithium ion battery 52 and the lead battery 51, as indicated by black arrows in FIG. charged. Moreover, since the internal resistance of the lithium ion battery 52 is smaller than the internal resistance of the lead battery 51 , most of the generated current is supplied to the lithium ion battery 52 .

As shown in FIGS. 3 to 5, the switches SW1 and SW2 are kept on when the starter generator 16 is controlled in the combustion power generation state, the regenerative power generation state, and the power generation suspension state. In other words, in the vehicle power supply device 10, charging and discharging of the lithium ion battery 52 can be controlled only by controlling the voltage generated by the starter generator 16 without performing switching control of the switches SW1 and SW2. As a result, not only can the charging and discharging of the lithium ion battery 52 be easily controlled, but also the durability of the switches SW1 and SW2 can be improved.

[Engine restart under idling stop control]
An idling control unit 86 of the main controller 80 executes idling stop control to automatically stop and restart the engine 12 . The idling control unit 86 stops the engine 12 by performing a fuel cut or the like when a predetermined stop condition is satisfied while the engine is running. 16 to restart the engine 12. The conditions for stopping the engine 12 include, for example, that the vehicle speed is below a predetermined value and that the brake pedal is depressed. Further, the conditions for starting the engine 12 include, for example, that the brake pedal is released and that the accelerator pedal is started to be depressed. The idling control unit 86 outputs control signals to the engine control unit 81 and the ISG control unit 82 to control the engine 12 and the starter generator 16 when executing the idling stop control.

Further, the idling control unit 86 controls the starter generator 16 to the power running state to start and rotate the engine 12 when the starting condition is satisfied while the engine is stopped by the idling stop control. Here, FIG. 6 is a diagram showing an example of the current supply state when the starter generator 16 is controlled to the power running state. As shown in FIG. 6, when the starter generator 16 is controlled to be in the power running state when the engine is restarted under the idling stop control, the switch SW1 is switched from the ON state to the OFF state. That is, when the engine 12 is started and rotated by the starter generator 16, the switch SW1 is switched to the OFF state, and the first power supply system 71 and the second power supply system 72 are disconnected from each other. As a result, even when a large current is supplied from the lithium-ion battery 52 to the starter generator 16, it is possible to prevent a momentary voltage drop in the electrical equipment group 64 of the first power supply system 71. 64 etc. can function normally.

[Motor assist control]
The assist control unit 87 of the main controller 80 controls the starter generator 16 to the power running state at the time of start or acceleration, and executes motor assist control for assisting the engine 12 with the starter generator 16 . Note that the assist control unit 87 outputs a control signal to the ISG control unit 82 to control the starter generator 16 when executing the motor assist control.

Here, FIG. 7 is a diagram showing an example of the current supply state when the starter generator 16 is controlled to the power running state. As shown in FIG. 7, when the starter generator 16 is controlled to the power running state with the motor assist control, both the switches SW1 and SW2 are kept on. In this way, when the engine 12 is assisted by the starter generator 16, both the lead battery 51 and the lithium ion battery 52 are connected to the electric device group 64 by turning on the switches SW1 and SW2. there is As a result, the power supply voltage of the electric device group 64 can be stabilized, and the reliability of the vehicle power supply device 10 can be improved.

As described above, when the engine is restarted by the starter generator 16, the switch SW1 is switched off, while when the starter generator 16 assists the motor, the switch SW1 is kept on. In other words, engine restart is a situation in which the stopped engine 12 is started to rotate by the starter generator 16, and the power consumption of the starter generator 16 is likely to increase. On the other hand, the motor-assisted state is a state in which the rotating engine 12 is auxiliary driven by the starter generator 16, and a state in which the power consumption of the starter generator 16 is suppressed. As described above, in the motor assist control, since the power consumption of the starter generator 16 is suppressed, even if the switch SW1 is kept on, a large current does not flow from the lead battery 51 to the starter generator 16. The power supply voltage of the electrical equipment group 64 can be stabilized.

[Engine initial start control, lead battery supplementary charge control]
Subsequently, the engine initial start control for starting the engine 12 using the starter motor 33 will be described, and then the lead battery supplementary charge control by the starter generator 16 after the engine initial start will be described. Here, FIG. 8 is a diagram showing an example of the current supply state in the engine initial start control. Also, FIG. 9 is a diagram showing an example of a current supply state in the lead battery auxiliary charging control.

When the control system of the vehicle 11 is activated and the engine 12 is first started, that is, when the engine 12 is started by operating the starter button, the starter motor 33 performs starting rotation of the engine 12 . In this engine initial start control, as shown in FIG. 8, the switch SW1 is controlled to be off, the switch SW2 is controlled to be off, and the starter relay 37 is controlled to be on. As a result, current is supplied from the lead battery 51 to the starter motor 33, and the engine 12 is started by rotating the starter motor 33. As shown in FIG.

When the engine 12 is started by the starter motor 33 in this manner, the starter relay 37 is switched off, the switch SW1 is switched on, and the starter generator 16 enters the combustion power generation state, as shown in FIG. controlled. That is, when the engine 12 is started, the switch SW1 is switched to the ON state while the switch SW2 is kept OFF, and the starter generator 16 is controlled to the combustion power generation state. As a result, the lead battery 51 can be positively charged by the starter generator 16, and the state of charge SOC of the lead battery 51, which decreases when the vehicle is stopped or when the engine is first started, can be restored.

That is, dark current flows from the lead battery 51 to the electrical equipment group 64 while the vehicle is stopped, and a large current flows from the lead battery 51 to the starter motor 33 when the engine is first started. The state of charge SOC gradually decreases. For this reason, the reduced state of charge SOC of the lead battery 51 is restored by executing the lead battery auxiliary charging control after the engine is first started. The lead battery supplementary charge control may be continued for a predetermined period of time, or may be continued until the state of charge SOC of the lead battery 51 recovers to a predetermined value.

[Engine stall prevention control 1]
The engine stall prevention control 1 executed by the vehicle power supply device 10 will be described below. As described above, in the combustion power generation state of the starter generator 16, the starter generator 16 is driven by the engine 12, so there is a risk that the engine load will increase and cause an engine stall. Therefore, when the starter generator 16 is controlled to the combustion power generation state, that is, when the engine power generation control for generating power using the engine power is executed, the main controller 80 performs the engine stall prevention control 1 for preventing the engine stall. Run.

FIG. 10 is a timing chart showing an example of changes in the engine rotation speed Ne, ISG torque, etc. when the engine stall prevention control 1 is executed. Note that the ISG torque shown in FIG. 10 is the power generation torque and power running torque of the starter generator 16 . FIGS. 11A and 11B are diagrams showing an example of current supply conditions when the engine stall prevention control 1 is executed. In FIGS. 11A and 11B, black arrows indicate current supply conditions, and white arrows indicate torque transmission conditions.

First, the execution state of the engine power generation control shown in FIG. 10 is a state in which the engine 12 is operated in an idling state while the vehicle is stopped or during deceleration just before the vehicle is stopped, and the starter generator 16 is controlled to a combustion power generation state. It is a situation where As shown in FIG. 10, in the engine power generation control, the engine speed Ne is controlled to a predetermined idling speed (idling speed) Nid (symbol a1), and the starter generator 16 is controlled to a combustion power generation state (power generation state). (symbol b1). Here, the idling speed Nid is the speed maintained by the engine 12 overcoming the engine load, mechanical loss, etc. under the condition that the accelerator pedal is not operated by the occupant. The idling speed Nid changes according to the power generation torque of the starter generator 16, the cooling water temperature of the engine 12, the operating condition of the compressor (not shown), and the like.

For example, when the power generation torque of the starter generator 16 is large, the idling speed Nid is set high, while when the power generation torque of the starter generator 16 is small, the idling speed Nid is set low. Further, when the cooling water temperature of the engine 12 is low, the idling speed Nid is set high, and when the cooling water temperature of the engine 12 is high, the idling speed Nid is set low. When the compressor of the air conditioner (not shown) operates, the idling speed Nid is set high. When the compressor of the air conditioner stops, the idling speed Nid is set low.

As shown in FIG. 11A, in the engine power generation control, the starter generator 16 is controlled to the combustion power generation state while the starter generator 16 is being driven by the engine 12 . Both switches SW1 and SW2 are controlled to be on, and the generated current from the starter generator 16 is supplied to the lead battery 51, the lithium ion battery 52 and the electrical equipment group 64. At this time, the load acting on the engine 12, that is, the power generation torque of the starter generator 16 varies depending on the internal resistance of the batteries 51 and 52, current consumption of the electrical equipment group 64, and the like. Moreover, since the engine torque output in the idling state is small, there is a possibility that the engine may stop, that is, the engine may stall depending on the fluctuations in the engine load and the engine torque.

Therefore, as shown in FIG. 10, the main controller 80 controls the engine speed Ne to decrease due to fluctuations in the engine load and engine torque under the condition that the engine power generation control is executed (symbol a2). falls below the assistance start threshold value N1 (reference a3), it is determined that there is a risk of engine stall. Then, the main controller 80 rapidly increases the power running torque of the starter generator 16 (symbol b2), and switches the starter generator 16 from the combustion power generation state to the power running state (symbol b3).

As a result, the engine speed Ne can be increased using the starter generator 16 (reference a4), and engine stall can be avoided. That is, as shown in FIG. 11(B), current is supplied from the lithium ion battery 52 to the starter generator 16 , and the engine 12 is driven by the starter generator 16 . As a result, engine stall can be avoided and the operating state of the engine 12 can be continued. Since the internal resistance of the lithium ion battery 52 is smaller than the internal resistance of the lead battery 51 , most of the consumption current of the starter generator 16 is supplied from the lithium ion battery 52 .

In this manner, when the engine 12 is assist-driven by the starter generator 16 and the engine speed Ne exceeds the assistance end threshold value N2 higher than the assistance start threshold value N1 (reference a5), the main controller 80 eliminates the possibility of engine stall. It is determined that Then, the main controller 80 gently decreases the power running torque of the starter generator 16 toward "0" (reference b4), and switches the starter generator 16 from the power running state to the combustion power generation state (reference b5). When the engine stall is avoided in this way, the starter generator 16 is again controlled to the combustion power generation state, and the engine power generation control for charging the batteries 51 and 52 is continued as shown in FIG. 11(A). .

As described above, in the engine stall prevention control 1, the starter generator 16 is switched to the power running state when the engine speed Ne falls below the assistance start threshold value N1, and when the engine speed Ne exceeds the assistance end threshold value N2, the starter generator 16 is switched to the power generation state. Here, the assistance start threshold N1 and the assistance end threshold N2 are set based on the idling rotation speed Nid of the engine 12, and are set lower than the idling rotation speed Nid. For example, the auxiliary start threshold value N1 is set by multiplying the idling speed Nid by a predetermined coefficient (for example, 0.5) (N1=Nid×0.5). Further, the auxiliary termination threshold value N2 is set by multiplying the idling speed Nid by a predetermined coefficient (for example, 0.65) (N2=Nid×0.65). By setting the auxiliary start threshold value N1 and the auxiliary end threshold value N2 based on the idling speed Nid in this way, even if the idling speed Nid fluctuates according to the power generation torque, etc., the auxiliary start threshold value N1 can be appropriately set. and the auxiliary end threshold value N2 can be set.

Further, by setting the auxiliary start threshold value N1 lower than the idling speed Nid, the power running start timing of the starter generator 16 can be delayed. As a result, the power consumption of the starter generator 16 can be suppressed without unnecessarily controlling the starter generator 16 to the power running state in a situation where engine stall does not occur. Further, by setting the auxiliary end threshold value N2 lower than the idling speed Nid, the power running stop timing of the starter generator 16 can be advanced. As a result, when the engine stall is avoided, power consumption of the starter generator 16 can be suppressed without continuing the power running state of the starter generator 16 unnecessarily.

Further, as shown in FIG. 10, when the engine speed Ne falls below the auxiliary start threshold value N1 and the starter generator 16 is switched from the power generation state to the power running state, the power running torque of the starter generator 16 is rapidly increased at the first change speed. It is increased (symbol b2). By quickly increasing the power running torque of the starter generator 16 in this way, engine stall can be prevented while delaying the power running start timing of the starter generator 16 . On the other hand, when the engine speed Ne exceeds the assistance end threshold value N2 and the starter generator 16 is switched from the power running state to the power generation state, the power running torque of the starter generator 16 is gradually changed at a second change speed slower than the first change speed. It is decreased (symbol b4). By gently reducing the power running torque of the starter generator 16 in this manner, the starter generator 16 can be controlled without giving the passenger a sense of discomfort due to torque fluctuations.

Next, the aforementioned engine stall prevention control 1 will be described along a flowchart. FIG. 12 is a flow chart showing an example of the execution procedure of the engine stall prevention control 1. In FIG. LiB shown in FIG. 12 is the lithium ion battery 52 .

As shown in FIG. 12, in step S10, the starter generator 16 is controlled to the combustion power generation state. In this combustion power generation state, the switches SW1 and SW2 are controlled to be on. In subsequent step S11, it is determined whether or not the engine speed Ne is below the assistance start threshold value N1. If it is determined in step S11 that the engine speed Ne is less than the auxiliary start threshold value N1, that is, if it is determined that there is a risk of engine stall, the process proceeds to step S12, and the lithium ion battery 52 can be discharged. It is determined whether or not In step S12, the state in which the lithium ion battery 52 can be discharged means, for example, that the battery module 74 is operating normally and the temperature of the lithium ion battery 52 is within a predetermined range (eg, −10° C. or higher, 60° C. below), and the state of charge SOC of the lithium ion battery 52 is maintained at a predetermined value (for example, 20%) or higher.

When it is determined in step S12 that the lithium ion battery 52 can be discharged, the process proceeds to step S13, in which the starter generator 16 is switched from the power generation state to the power running state. In this way, after determining that the lithium ion battery 52 can be discharged, the starter generator 16 is controlled to the power running state, so that current can be appropriately supplied from the lithium ion battery 52 to the starter generator 16. As a result, the engine 12, which is likely to stall, can be appropriately assisted driven by the starter generator 16. FIG.

In subsequent step S14, it is determined whether or not the engine speed Ne, which is increased by the assist drive of the starter generator 16, exceeds the assistance end threshold value N2 higher than the assistance start threshold value N1. When it is determined in step S14 that the engine speed Ne exceeds the assistance termination threshold value N2, the situation is such that the possibility of engine stall has been eliminated. lowered to

Then, in step S16, it is determined whether or not the power running state of the starter generator 16 has stopped, that is, whether or not the power running torque has decreased to "0". When it is determined in step S16 that the starter generator 16 is in the power running state, the process returns to step S14, and the reduction of the power running torque is continued. On the other hand, when it is determined in step S16 that the power running state of the starter generator 16 has stopped, the process proceeds to step S17, and the starter generator 16 is controlled to the combustion power generation state.

On the other hand, if it is determined in step S14 that the engine rotation speed Ne is equal to or lower than the assistance termination threshold value N2 under the condition that the starter generator 16 is assisted, the process proceeds to step S18, in which the power running of the starter generator 16 is performed. It is determined whether or not the elapsed time Ta from the start exceeds a predetermined time limit T1 (for example, 3 seconds). When it is determined in step S18 that the elapsed time Ta is equal to or shorter than the time limit T1, the process returns to step S13 and the power running state of the starter generator 16 is continued. On the other hand, if it is determined in step S18 that the elapsed time Ta has exceeded the time limit T1, the assist driving by the starter generator 16 is difficult. be done.

[Engine stall prevention control 2]
In the above-described engine stall prevention control 1, as shown in FIG. 3, when both switches SW1 and SW2 are controlled to be in the ON state and the starter generator 16 is controlled to be in the combustion power generation state, the engine stall prevention control is executed. However, it is not limited to this. For example, as shown in FIG. 9, the engine stall prevention control may be executed when the switch SW1 is controlled to be ON, the switch SW2 is controlled to be OFF, and the starter generator 16 is controlled to be in the combustion power generation state. .

The engine stall prevention control 2 executed by the vehicle power supply device 10 will be described below. As described above, in the combustion power generation state of the starter generator 16, the starter generator 16 is driven by the engine 12, so there is a risk that the engine load will increase and cause an engine stall. Therefore, when the starter generator 16 is controlled to the combustion power generation state, that is, when the engine power generation control for generating power using the engine power is executed, the main controller 80 performs the engine stall prevention control 2 for preventing the engine stall. Run.

FIG. 13 is a timing chart showing an example of changes in the engine rotation speed Ne, ISG torque, etc. when the engine stall prevention control 2 is executed. Note that the ISG torque shown in FIG. 13 is the power generation torque and power running torque of the starter generator 16 . Also, FIGS. 14A and 14B are diagrams showing an example of current supply conditions when the engine stall prevention control 2 is executed. In FIGS. 14A and 14B, black arrows indicate current supply conditions, and white arrows indicate torque transmission conditions.

First, the execution state of the engine power generation control shown in FIG. 13 is a state in which the engine 12 is operated in an idling state and the starter generator 16 is controlled to a combustion power generation state during lead battery supplementary charging after the engine is first started. It is a situation where As shown in FIG. 13, in the engine power generation control, the engine speed Ne is controlled to a predetermined idling speed (idling speed) Nid (symbol a1), and the starter generator 16 is controlled to a combustion power generation state (power generation state). (symbol b1). Here, the idling speed Nid is the speed maintained by the engine 12 overcoming the engine load, mechanical loss, etc. under the condition that the accelerator pedal is not operated by the occupant. The idling speed Nid changes according to the power generation torque of the starter generator 16, the cooling water temperature of the engine 12, the operating condition of the compressor (not shown), and the like.

For example, when the power generation torque of the starter generator 16 is large, the idling speed Nid is set high, while when the power generation torque of the starter generator 16 is small, the idling speed Nid is set low. Further, when the cooling water temperature of the engine 12 is low, the idling speed Nid is set high, and when the cooling water temperature of the engine 12 is high, the idling speed Nid is set low. When the compressor of the air conditioner (not shown) operates, the idling speed Nid is set high. When the compressor of the air conditioner stops, the idling speed Nid is set low.

As shown in FIG. 14A, in the engine power generation control, the starter generator 16 is controlled to the combustion power generation state while the starter generator 16 is being driven by the engine 12 . Switch SW1 is controlled to be on, while switch SW2 is controlled to be off. At this time, the load acting on the engine 12, that is, the power generation torque of the starter generator 16 varies depending on the internal resistance of the lead battery 51, current consumption of the electrical equipment group 64, and the like. Moreover, since the engine torque output in the idling state is small, there is a possibility that the engine may stop, that is, the engine may stall depending on the fluctuations in the engine load and the engine torque.

Therefore, as shown in FIG. 13, the main controller 80 controls the engine rotation speed Ne to decrease due to fluctuations in the engine load and engine torque under the condition that the engine power generation control is executed (symbol a2). falls below the assistance start threshold value N1 (reference a3), it is determined that there is a risk of engine stall. Then, the main controller 80 switches the switch SW2 from the OFF state to the ON state (symbol c1), rapidly increases the power running torque of the starter generator 16 (symbol b2), and switches the starter generator 16 from the combustion power generation state to the power running state. (symbol b3).

As a result, the engine speed Ne can be increased using the starter generator 16 (reference a4), and engine stall can be avoided. That is, as shown in FIG. 14(B), current is supplied from the lithium ion battery 52 to the starter generator 16 , and the engine 12 is driven by the starter generator 16 . As a result, engine stall can be avoided and the operating state of the engine 12 can be continued. Since the internal resistance of the lithium ion battery 52 is smaller than the internal resistance of the lead battery 51 , most of the consumption current of the starter generator 16 is supplied from the lithium ion battery 52 .

In this manner, when the engine 12 is assist-driven by the starter generator 16 and the engine speed Ne exceeds the assistance end threshold value N2 higher than the assistance start threshold value N1 (reference a5), the main controller 80 eliminates the possibility of engine stall. It is determined that Then, the main controller 80 gradually decreases the power running torque of the starter generator 16 toward "0" (symbol b4), switches the switch SW2 from the ON state to the OFF state (symbol c2), and places the starter generator 16 in the power running state. to the combustion power generation state (symbol b5). When the engine stall is avoided in this way, the starter generator 16 is again controlled to the combustion power generation state, and the engine power generation control for charging the batteries 51 and 52 is continued as shown in FIG. 14(A). .

As described above, in the engine stall prevention control 2, the switch SW2 is switched to the ON state and the starter generator 16 is switched to the power running state when the engine speed Ne falls below the assistance start threshold value N1. On the other hand, when the engine speed Ne exceeds the auxiliary termination threshold value N2, the switch SW2 is switched to the OFF state, and the starter generator 16 is switched to the power generation state. Here, the assistance start threshold N1 and the assistance end threshold N2 are set based on the idling rotation speed Nid of the engine 12, and are set lower than the idling rotation speed Nid. For example, the auxiliary start threshold value N1 is set by multiplying the idling speed Nid by a predetermined coefficient (for example, 0.5) (N1=Nid×0.5). Further, the auxiliary termination threshold value N2 is set by multiplying the idling speed Nid by a predetermined coefficient (for example, 0.65) (N2=Nid×0.65). By setting the auxiliary start threshold value N1 and the auxiliary end threshold value N2 based on the idling speed Nid in this way, even if the idling speed Nid fluctuates according to the power generation torque, etc., the auxiliary start threshold value N1 can be appropriately set. and the auxiliary end threshold value N2 can be set.

Further, by setting the auxiliary start threshold value N1 lower than the idling speed Nid, the power running start timing of the starter generator 16 can be delayed. As a result, the power consumption of the starter generator 16 can be suppressed without unnecessarily controlling the starter generator 16 to the power running state in a situation where engine stall does not occur. Further, by setting the auxiliary end threshold value N2 lower than the idling speed Nid, the power running stop timing of the starter generator 16 can be advanced. As a result, when the engine stall is avoided, power consumption of the starter generator 16 can be suppressed without continuing the power running state of the starter generator 16 unnecessarily.

Further, as shown in FIG. 13, when the engine speed Ne falls below the auxiliary start threshold value N1 and the starter generator 16 is switched from the power generation state to the power running state, the power running torque of the starter generator 16 is rapidly increased at the first change speed. It is increased (symbol b2). By quickly increasing the power running torque of the starter generator 16 in this way, engine stall can be prevented while delaying the power running start timing of the starter generator 16 . On the other hand, when the engine speed Ne exceeds the assistance end threshold value N2 and the starter generator 16 is switched from the power running state to the power generation state, the power running torque of the starter generator 16 is gradually changed at a second change speed slower than the first change speed. It is decreased (symbol b4). By gently reducing the power running torque of the starter generator 16 in this manner, the starter generator 16 can be controlled without giving the passenger a sense of discomfort due to torque fluctuations.

Next, the aforementioned engine stall prevention control 2 will be described along a flowchart. FIG. 15 is a flow chart showing an example of the execution procedure of the engine stall prevention control 2. As shown in FIG. LiB shown in FIG. 15 is the lithium ion battery 52 .

As shown in FIG. 15, in step S20, the starter generator 16 is controlled to the combustion power generation state. In this combustion power generation state, the switch SW1 is controlled to be on, and the switch SW2 is controlled to be off. In subsequent step S21, it is determined whether or not the engine speed Ne is below the assistance start threshold value N1. If it is determined in step S21 that the engine speed Ne is lower than the auxiliary start threshold value N1, that is, if it is determined that there is a risk of engine stall, the process proceeds to step S22, and the lithium ion battery 52 can be discharged. It is determined whether or not In step S22, the state in which the lithium ion battery 52 can be discharged means, for example, that the battery module 74 is operating normally and the temperature of the lithium ion battery 52 is within a predetermined range (eg, −10° C. or higher, 60° C. below), and the state of charge SOC of the lithium ion battery 52 is maintained at a predetermined value (for example, 20%) or higher.

When it is determined in step S22 that the lithium ion battery 52 can be discharged, the process proceeds to step S23, where the switch SW2 is switched from the off state to the on state, and the process proceeds to step S24, where the starter generator 16 changes from the power generation state to the power running state. can be switched to Thus, after determining that the lithium ion battery 52 can be discharged, the switch SW2 is switched to the ON state and the starter generator 16 is controlled to the power running state. can be supplied. As a result, the engine 12, which is likely to stall, can be appropriately assisted driven by the starter generator 16. FIG.

In subsequent step S25, it is determined whether or not the engine speed Ne, which is increased by the assist drive of the starter generator 16, exceeds the assistance end threshold value N2 higher than the assistance start threshold value N1. If it is determined in step S25 that the engine speed Ne exceeds the assistance end threshold value N2, the situation is such that the possibility of engine stall has been eliminated. lowered to

Then, in step S27, it is determined whether or not the power running state of the starter generator 16 has stopped, that is, whether or not the power running torque has decreased to "0". When it is determined in step S27 that the starter generator 16 is in the power running state, the process returns to step S25, and the reduction of the power running torque is continued. On the other hand, when it is determined in step S27 that the power running state of the starter generator 16 has stopped, the process proceeds to step S28, the switch SW2 is switched to the OFF state, and the process proceeds to step S29, in which the starter generator 16 enters the combustion power generation state. controlled.

On the other hand, if it is determined in step S25 that the engine speed Ne is equal to or lower than the assistance end threshold value N2 under the condition that the starter generator 16 is assisted, the process proceeds to step S30, and the power running of the starter generator 16 is performed. It is determined whether or not the elapsed time Ta from the start exceeds a predetermined time limit T1 (for example, 3 seconds). When it is determined in step S30 that the elapsed time Ta is equal to or less than the time limit T1, the process returns to step S24, and the power running state of the starter generator 16 is continued. On the other hand, if it is determined in step S30 that the elapsed time Ta has exceeded the time limit T1, the situation is such that assist driving by the starter generator 16 is difficult. be done.

It goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. In the examples shown in FIGS. 10 and 13, the engine 12 is controlled to the idling state, but the present invention is not limited to this. The operating state of may be other than the idling state. Also, in the above description, the lead battery 51 is used as the first power storage body, but the present invention is not limited to this, and other types of batteries and capacitors may be used as the first power storage body. Moreover, although the lithium ion battery 52 is used as the second power storage body, the present invention is not limited to this, and other types of batteries and capacitors may be used as the second power storage body. Further, in the example shown in FIGS. 1 and 2, the switch SW2 is provided in the positive electrode line 54 of the lithium ion battery 52, but it is not limited to this. For example, a switch SW2 may be provided in the negative electrode line 59 of the lithium ion battery 52, as indicated by a dashed line in FIG. Further, in the above description, the main controller 80 is provided with various control units 81 to 87, but the present invention is not limited to this. Some or all of the various control units 81 to 87 may be provided in another controller.

10 vehicle power supply device 11 vehicle 12 engine 16 starter generator (generator motor)
33 starter motor (electrical load)
51 lead battery (first power storage body)
52 Lithium ion battery (second storage body)
56 positive electrode line (energization path)
63 Electrical Equipment (Electrical Load)
71 first power supply system 72 second power supply system 80 main controller 82 ISG control section (generator motor control section)
84 second switch control unit (switch control unit)
Ne Engine speed (engine speed)
N1 Auxiliary start threshold N2 Auxiliary end threshold Nid Idling speed (idling speed)
SW1 First switch SW2 Second switch

Claims (5)

A vehicle power supply device mounted on a vehicle,
a first power supply system including a first power storage body and an electric load connected to the first power storage body;
a second power supply system comprising: a generator motor connected to an engine; and a second power storage unit connected to the generator motor;
an energization path provided between the first power supply system and the second power supply system and connecting the first power storage body and the second power storage body in parallel;
A first power supply system provided in the conducting path and controlled to be in an ON state for connecting the first power supply system and the second power supply system and an OFF state for separating the first power supply system from the second power supply system. a switch;
a second switch provided in the second power supply system and controlled to be in an ON state for connecting the generator motor and the second power storage unit and to be controlled for an OFF state for disconnecting the generator motor from the second power storage unit; ,
Engine power generation control for controlling the generator motor to generate power in a state in which the generator motor is driven by the engine, the first switch is controlled to be on, and the second switch is controlled to be off. a generator motor controller that executes
has
The generator-motor control unit switches the generator-motor from a power generation state to a power running state when the rotational speed of the engine falls below an auxiliary start threshold under the state in which the engine power generation control is executed,
A switch control unit that controls the second switch turns the second switch from an off state to an on state when the rotational speed of the engine falls below the auxiliary start threshold under the state in which the engine power generation control is executed. switch to state
Vehicle power supply. A vehicle power supply device mounted on a vehicle,
a first power supply system including a first power storage body and an electric load connected to the first power storage body;
a second power supply system comprising: a generator motor connected to an engine; and a second power storage unit connected to the generator motor;
an energization path provided between the first power supply system and the second power supply system and connecting the first power storage body and the second power storage body in parallel;
a generator-motor control unit that executes engine power generation control for controlling the generator-motor to generate power while the generator-motor is driven by the engine;
has
The generator motor control unit
switching the generator motor from a power generation state to a power running state when the rotation speed of the engine falls below an auxiliary start threshold under the state in which the engine power generation control is executed ;
After switching the generator motor from the power generation state to the power running state, if the rotation speed of the engine exceeds an auxiliary end threshold higher than the auxiliary start threshold, switching the generator motor from the power running state to the power generation state;
The generator motor control unit
increasing the power running torque of the generator motor at a first rate of change when the rotation speed of the engine falls below the auxiliary start threshold and the generator motor is switched from the power generation state to the power running state;
When the rotation speed of the engine exceeds the auxiliary end threshold and the generator motor is switched from the power running state to the power generation state, the power running torque of the generator motor is decreased at a second change speed slower than the first change speed,
Vehicle power supply. In the vehicle power supply device according to claim 1 or 2 ,
wherein the auxiliary start threshold is lower than the idling speed of the engine;
Vehicle power supply. In the vehicle power supply device according to claim 2 ,
A first power supply system provided in the conducting path and controlled to be in an ON state for connecting the first power supply system and the second power supply system and an OFF state for separating the first power supply system from the second power supply system. a switch;
a second switch provided in the second power supply system and controlled to be in an ON state for connecting the generator motor and the second power storage unit and to be controlled for an OFF state for disconnecting the generator motor from the second power storage unit; ,
has
The generator motor control unit executes the engine power generation control under a state in which the first switch is controlled to be on and the second switch is controlled to be off.
Vehicle power supply. In the vehicle power supply device according to claim 1 ,
The generator motor control unit
After switching the generator-motor from the power generation state to the power running state when the rotation speed of the engine falls below the auxiliary start threshold under the state where the engine power generation control is executed,
switching the generator motor from a power running state to a power generation state when the rotation speed of the engine exceeds an auxiliary end threshold higher than the auxiliary start threshold;
Vehicle power supply.

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