Hybrid vehicle and vehicle-stop power generation control method

Abstract

To provide a hybrid vehicle and a vehicle-stop power generation control method of the same which can attain power generation control properly in a stopped state.SOLUTION: A hybrid vehicle, which comprises a power generator that is driven to generate electric power by an engine, a battery that stores electric power generated by the power generator and a control part that performs power generation control on the basis of SOC of the battery, when SOC drops down to a stop power generation-starting level SOCS when the vehicle is in a stopped state (a step 302:YES), executes vehicle-stop power generation by the power generator that is driven by the engine until the SOC rises to a vehicle-stop power generation finish level SOCT (a step 305) to changes the vehicle-stop power generation finish level SOCT in accordance with average vehicle speed in a predetermined time just before the vehicle is brought into the stopped state (steps 306-308).SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a power generation control technique for a vehicle in which a generator is driven by an engine (internal combustion engine). [Background technology]

[0002] Vehicles equipped with an idle stop function that stops the engine when the vehicle is stopped are becoming widespread. On the other hand, when the generator stops generating power due to the idle stop, the remaining capacity of the battery (hereinafter referred to as SOC (State Of Charge)) decreases due to power consumption by air conditioners, etc. If the SOC decreases too much, it becomes impossible to secure the power required for accelerating. In order to avoid this situation, it is necessary to drive the engine to generate power even while the vehicle is stopped (stationary power generation) and charge the battery. One example of a method for controlling such stationary power generation is disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-116271 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the stationary power generation control disclosed in Patent Document 1, in the case of a hybrid vehicle with a large battery capacity, it is necessary to operate the engine for a long time to charge the battery until the required SOC level is reached. In addition, idling stop is not possible even when the vehicle is stopped for a short time, such as when waiting at a traffic light. It is desirable to avoid such power generation while the vehicle is stopped as much as possible from the viewpoints of NVH (Noise, Vibration, Harshness) and fuel economy.

[0005] The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide a hybrid vehicle capable of achieving appropriate power generation control while the vehicle is stopped, and a method for controlling power generation while the vehicle is stopped. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, according to one embodiment of the present invention, a hybrid vehicle is provided which includes an engine, a generator driven by the engine to generate electricity, a battery for storing electricity generated by the generator, and a control unit which performs power generation control based on the state of charge (hereinafter referred to as SOC) of the battery, wherein the control unit includes a first function which, when the SOC falls to a stationary power generation start level while the vehicle is stopped, executes stationary power generation of the generator by the engine until the SOC rises to a stationary power generation end level, and a second function which changes the stationary power generation end level depending on the average vehicle speed during a predetermined time immediately before the vehicle enters a stationary state. In order to achieve the above-mentioned object, according to one embodiment of the present invention, there is provided a method for controlling power generation while stationary by a control unit in a hybrid vehicle which includes an engine, a generator driven by the engine to generate power, a battery which stores power generated by the generator, and a control unit which controls power generation based on a state of charge (hereinafter referred to as SOC) of the battery, wherein, when the vehicle is stopped, an average vehicle speed for a predetermined time period immediately prior to the vehicle being stopped is calculated, and when the SOC falls to a stationary power generation start level while the vehicle is stopped, a stationary power generation end level is set in accordance with the average vehicle speed, and stationary power generation of the generator is performed by the engine until the SOC rises from the stationary power generation start level to the stationary power generation end level. According to one embodiment of the present invention, the control unit can preliminarily set a map that specifies the direction and amount of change of the stationary power generation end level relative to the average vehicle speed, and change the stationary power generation end level by referring to the map. Furthermore, according to one embodiment of the present invention, the control unit sets a first threshold value and a second threshold value greater than the first threshold value for the average vehicle speed, and in the second function, if the average vehicle speed is less than the first threshold value, the parked vehicle power generation end level is maintained at a normal value, if the average vehicle speed is greater than or equal to the first threshold value and less than the second threshold value, the parked vehicle power generation end level is lowered from the normal value by a predetermined amount, and if the average vehicle speed is greater than or equal to the second threshold value, the parked vehicle power generation end level is raised from the normal value by a predetermined amount. Furthermore, according to one embodiment of the present invention, the control unit sets a first threshold value for the average vehicle speed, a second threshold value greater than the first threshold value, and a third threshold value between the first threshold value and the second threshold value, and in the second function, if the average vehicle speed is less than the first threshold value, the stationary vehicle power generation end level is maintained at a normal value, and between the first threshold value and the third threshold value, the amount by which the stationary vehicle power generation end level is reduced is gradually increased toward a predetermined value as the average vehicle speed increases, between the third threshold value and the second threshold value, the amount by which the stationary vehicle power generation end level is reduced is gradually decreased toward zero as the average vehicle speed increases, and the amount by which the stationary vehicle power generation end level is increased is gradually increased as the average vehicle speed increases above the second threshold value. Furthermore, according to one embodiment of the present invention, when the control unit predicts that the average vehicle speed during driving after the vehicle is stopped will be equal to or greater than the second threshold value while the vehicle is stopped, the control unit can cancel the control of lowering the stationary power generation stop level. Furthermore, according to one embodiment of the present invention, when there is power consumption other than for driving the vehicle to travel, the control unit can raise the stationary power generation end level by a predetermined amount according to the power consumption. Effect of the Invention

[0007] According to one embodiment of the present invention, the stationary power generation end level is changed according to the average vehicle speed during a predetermined time immediately before the vehicle comes to a stop, thereby enabling appropriate power generation control in a stationary state. For example, in stationary power generation control, the balance between the priority of charging and the priority of idling stop can be appropriately set according to the average vehicle speed. Furthermore, according to one embodiment of the present invention, the parked power generation end level can be changed by referring to a map that specifies the direction and amount of change in the parked power generation end level, thereby making it possible to flexibly set a parked power generation control pattern according to the driving conditions. According to one embodiment of the present invention, the stationary power generation end level is lowered if the average vehicle speed is between the first and second thresholds, and is raised if the average vehicle speed is equal to or greater than the second threshold. This shortens the period during which the engine is driven to generate electricity while the vehicle is stationary when charging is expected while driving, and lengthens it when power is required for high-speed driving. According to one embodiment of the present invention, a third threshold is set between the first threshold and the second threshold, and the amount by which the stationary power generation end level is lowered or raised is gradually changed according to the average vehicle speed, thereby enabling highly accurate stationary power generation control. For example, the balance between the priority of charging and the priority of idling stop can be set with high accuracy according to the driving conditions. Furthermore, according to one embodiment of the present invention, when it is predicted that the vehicle will travel at high speed after stopping, the control for lowering the stationary power generation stop level can be cancelled, thereby making it possible to ensure battery capacity. Furthermore, according to one embodiment of the present invention, when there is power consumption other than that required for driving the vehicle, the level at which power generation while the vehicle is parked is increased, thereby making it possible to ensure battery capacity. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram showing an example of a hybrid vehicle to which a stopping control method according to an embodiment of the present invention is applied; [Diagram 2] 1 is a block diagram showing a schematic configuration of a control system in a hybrid vehicle according to an embodiment of the present invention. [Diagram 3] 4 is a schematic diagram showing an example of a change in battery SOC to explain the general operation of the stationary vehicle power generation control according to the present embodiment; FIG. [Figure 4] 4 is a flowchart showing an example of a stationary vehicle power generation control method according to the present embodiment. [Diagram 5] 5 is a graph showing a first example and a second example of a stationary vehicle power generation control map in the stationary vehicle power generation control method according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] 1. Vehicle configuration 1, a hybrid vehicle 10 equipped with a stationary vehicle power generation control function according to an embodiment of the present invention has a control unit 100 that executes stationary vehicle power generation control and other vehicle controls, which will be described later. The control unit 100 controls an engine 102, a generator 103, a drive motor 104, and a clutch CL while monitoring an SOC signal and other signals of a battery 101, as will be described later. The battery 101 is connected to the generator 103 and the motor 104, and stores the generated power of the generator 103 and supplies the stored power to the motor 104.

[0010] The rotor shaft of the generator 103 is mechanically connected to the output shaft of the engine 102, and generates electricity by the rotation of the engine 102. The generator 103 can also function as a motor. Specifically, it can be operated as a starter for starting the engine 102, or the engine 102 can be rotated as a load to be used for waste electricity.

[0011] The clutch CL mechanically disconnects or connects the transmission of the rotational torque of the engine 102 to the gear mechanism 105. By disconnecting the clutch CL, the output shaft of the engine 102 is mechanically connected only to the generator 103, and the hybrid vehicle 10 is in the EV driving mode or the series driving mode. By engaging the clutch CL, the output shaft of the engine 102 is connected not only to the generator 103 but also to the gear mechanism 105. The gear mechanism 105 transmits the driving torque of the motor 104 to the front wheels 106, and can also transmit the driving torque of the engine 102 to the front wheels 106 when the clutch CL is in an engaged state. The rear wheels 107 may be driven by a rear motor separate from the motor 104.

[0012] If the hybrid vehicle 10 is a plug-in hybrid type, the battery 101 may be charged with power supplied from a commercial household power source or a quick-charging power source at a charging station via the external charging unit 108, or, although not shown, power may be supplied from the battery 101 to home appliances via an external power supply unit. Although not shown, the vehicle 10 may be provided with a camera or a navigation system for monitoring the front and / or rear. As will be described later, a monitoring means such as a camera can be used for the stationary power generation control.

[0013] 2. Control System As illustrated in Fig. 2, the control unit 100 controls the overall operation of the hybrid vehicle 10. In detail, the control unit 100 is made up of various control units including an engine control unit 110, a generator control unit 111, a motor control unit 112, a stationary power generation control unit 113, a charging control unit 114, and a vehicle control unit 115. Here, the vehicle control unit 115 inputs various detection amounts and various operation information including the vehicle speed V, the vehicle's power supply power, the air conditioning power, and an SOC signal indicating the charging state of the battery 101, and executes output control of the engine 102, the generator 103, the motor 104, and the like. The engine 102 is controlled by the engine control unit 110. The generator 103 is controlled by the generator control unit 111 through an inverter INV(1). The motor 104 is controlled by the motor control unit 112 through an inverter INV(2).

[0014] A charging control unit 114 detects the state of charge of the battery 101, and outputs an SOC signal to a vehicle control unit 115. A stationary power generation control unit 113 controls the engine 102 based on the vehicle speed V and the SOC value, as described below, to perform stationary power generation control.

[0015] The control unit 100 may include a processor such as a CPU (Central Processing Unit), a ROM (Read-only memory) that stores a control program executed by the processor, a RAM (Random access memory) as an operating area for the control program, and an interface unit with peripheral circuits, etc. The method for controlling power generation when the vehicle is parked according to this embodiment may be implemented by executing a program on the processor of the control unit 100. The method for controlling power generation when the vehicle is parked according to this embodiment will be described in detail below.

[0016] 3. Power generation control while stationary First, normal power generation control according to the SOC value of the battery 101 will be described with reference to FIG.

[0017] As shown in FIG. 3, the control unit 100 has three SOC control levels: Charge-Sustaining SOC (CSSOC), Stationary Power Generation End SOC T and SOC when power generation starts S CSSOC is a control level that makes it easier to drive the engine 102 and maintains the charge level of the battery 101.

[0018] Stopped power generation start SOC S is the control level that can guarantee the minimum amount of power required for starting the engine and accelerating when joining the highway. Therefore, the SOC value is SOC S When the voltage drops to this level, the engine 102 is started and the generator 103 starts generating electricity even if the vehicle is stopped. T is the control level at which stationary power generation can be terminated, and the SOC value frequently changes during normal driving. S The value is set to a value that does not fall below the threshold (here, the normal value).

[0019] 3, if the battery 101 is not charged while driving, the charge level of the battery 101 decreases and the SOC value decreases (arrow 201). If the SOC value falls below the CSSOC, the control unit 100 makes it easier to drive the engine 102, in an attempt to maintain the charge level of the battery 101. In this case, unless the idle stop is released, depending on the driving conditions, the engine 102 may not start even if the SOC value falls below the CSSOC, causing the SOC value to drop further (arrow 202). For example, there are cases where power is consumed when the vehicle is stopped or at a speed close to the CSSOC but the engine is not started due to consideration of NVH, or where power generation is insufficient while driving at high output, such as on a long hill or at high speed.

[0020] The SOC value of the battery 101 is the SOC when the vehicle is stopped and power generation starts. S When the SOC value drops to 0.0000, even if the vehicle is stopped or is stopped at a speed below a predetermined speed, the control unit 100 starts the engine 102 to drive the generator 103 to generate electricity and starts charging the battery 101. This stationary power generation increases the SOC value of the battery 101 (arrow 203), and the stationary power generation end SOC T When this is reached, the control unit 100 ends the stationary power generation.

[0021] In the stationary vehicle power generation control according to this embodiment, the stationary vehicle power generation end SOC T The level of is raised or lowered according to the average vehicle speed in a predetermined time immediately before the vehicle is stopped (arrow 204). In other words, the stationary power generation driving time of engine 102 can be extended or shortened by expanding or contracting the stationary power generation region according to the average vehicle speed. That is, the balance between prioritizing idling stop or battery charging while the vehicle is stopped can be appropriately set according to the driving conditions. The stationary power generation control method according to this embodiment will be described in detail below with reference to FIG. 4. Here, the stationary power generation control unit 113 is configured to set a first threshold value V TH1 and the second threshold V TH2 (V TH1 <V TH2 ) is set in advance.

[0022] In FIG. 4, when the vehicle 10 is stopped in a low SOC state where the SOC value of the battery 101 is below the CSSOC, the stationary vehicle power generation control unit 113 calculates a predetermined time T P Average vehicle speed within V ADV (Step 301). P The length of can be set from the driving history of the vehicle 10, for example, T P =2~5 minutes.

[0023] The stationary vehicle power generation control unit 113 determines whether the SOC value of the battery 101 is a stationary vehicle power generation start SOC S (Step 302), and S If the SOC has not decreased to the SOC value (NO in step 302), the vehicle-parked power generation control is not executed. S If the calculated average vehicle speed V ADV is the first threshold V TH1 Then, it is determined whether the vehicle has exceeded the predetermined threshold (step 303), and the vehicle-parking power generation control described below is executed.

[0024] Average vehicle speed V ADV is the first threshold V TH1 If the result is NO in step 303, the stationary vehicle power generation control unit 113 determines whether the stationary vehicle power generation end SOC T is maintained at a normal value (step 304), and the SOC value of the battery 101 reaches the normal SOC at the end of stationary power generation. T In other words, power generation while the vehicle is stationary is continued until the average vehicle speed V ADV is the first threshold V TH1 In the following cases, it can be determined that the vehicle is in a situation where power generation while driving cannot be expected due to traffic congestion, etc., and it is necessary to proceed with charging sufficiently even when the vehicle is stopped. In order to make such a judgment, the first threshold value V TH1 is set, for example, V TH1 =30km / h.

[0025] Average vehicle speed V ADV is the first threshold V TH1If it exceeds the calculated average vehicle speed V ADV is the second threshold V TH2 It is determined whether the average vehicle speed V ADV is the second threshold V TH2 If so (NO in step 306), the stationary vehicle power generation control unit 113 determines whether the stationary vehicle power generation end SOC T is raised above the normal value (step 307), and the SOC value of the battery 101 is raised to the stationary power generation end SOC T In other words, power generation while the vehicle is stationary is continued until the average vehicle speed V ADV is the second threshold V TH2 In the above cases, it is judged that the vehicle is temporarily stopped while driving at high speed. Therefore, since there is a possibility that electric power will be required when accelerating again, the SOC for stopping the vehicle is set to 0. T It is necessary to set the second threshold value V higher than the normal value and extend the time the engine operates to generate electricity even when the vehicle is stopped in preparation for the demand for electricity. TH2 is set, for example, V TH2 =60~100km / h.

[0026] Average vehicle speed V ADV is the second threshold V TH2 If it is less than 100 msec (YES in step 306), the stationary vehicle power generation control unit 113 determines whether the stationary vehicle power generation end SOC T is lowered below the normal value (step 308), and the SOC value of the battery 101 is lowered to the stationary power generation end SOC T In other words, power generation while the vehicle is stationary is continued until the average vehicle speed V ADV is the first threshold V TH1 and the second threshold V TH2 If the vehicle is stopped within this range, it can be determined that the vehicle is stopped temporarily and power generation during driving can be expected, and the time during which the engine is driven for generating power during the vehicle stop is shortened to prioritize idling stop, and the engine 102 is operated during driving to generate power.

[0027] 4. Working Example In the above-described embodiment, the stationary vehicle power generation control unit 113 controls the average vehicle speed V ADV Stopped power generation end SOCT A stationary power generation control map that specifies how to change the stationary power generation end SOC may be stored. T It is possible to arbitrarily set the manner in which the above change is made. An example of the stationary vehicle power generation control map will be described below.

[0028] The first example of FIG. 5 is a stationary vehicle power generation control map showing one example of the stationary vehicle power generation control method described above. According to the first example of the stationary vehicle power generation control map, the average vehicle speed V ADV is the first threshold V TH1 If it is below, the stop power generation end SOC T is kept at its normal value, and the first threshold V TH1 and the second threshold V TH2 If it is between the time when the train stops and the power generation ends, SOC T is lowered by a certain amount from the normal value, and the second threshold V TH2 If it is equal to or greater than the normal value, it is raised by a predetermined amount. These lowering and raising amounts are each set to a fixed value, and can be set according to the forecast of the power demand in each direction.

[0029] The second example of FIG. 5 is a stationary vehicle power generation control map showing another example of the stationary vehicle power generation control method described above. According to the second example of the stationary vehicle power generation control map, the first threshold value V TH1 and the second threshold V TH2 At least one third threshold value V THM The average vehicle speed V ADV is the first threshold V TH1 If it is below, the stop power generation end SOC T is maintained at its normal value (zero change). The first threshold V TH1 and the third threshold V THM Between the third threshold V THM and the second threshold V TH2 Between the second threshold V TH2 Above this level, the amount of increase from the normal value gradually increases.

[0030] In this way, the SOC at which the vehicle stops generating electricity T The reduction and increase of the average vehicle speed VADV By gradually changing the threshold value V according to the driving conditions, the balance between the priority of charging and the priority of idling can be set with high accuracy according to the driving conditions. THM may be changed according to the driving history and driving conditions, and the first threshold value V TH1 and the second threshold V TH2 A plurality of such electrodes may be provided between the electrodes.

[0031] In addition, if the change in the power demand in the traveling direction can be predicted using the front camera of the vehicle 10, the SOC for stopping the vehicle power generation can be adjusted according to the situation in the traveling direction. T For example, when an entrance to a highway or an uphill section is recognized, the average vehicle speed V ADV is the second threshold V TH2 Therefore, in order to proceed with charging, the first threshold V TH1 and the second threshold V TH2 Stopped power generation end SOC between T Conversely, if an increase in power demand in the direction of travel is predicted, the SOC for stopping and power generation termination can be canceled. T can also be raised.

[0032] Also, the average vehicle speed V ADV The nearest neighbor time T P The length of the time can be set based on the driving history of the vehicle 10, but can also be changed according to the vehicle speed.

[0033] In addition, when there is power consumption other than driving the motor of the vehicle 10, such as use of air conditioning, the stop power generation end SOC T It is desirable to increase the power consumption by a certain amount. [Explanation of symbols]

[0034] 10 Hybrid vehicles 100 Control section 101 Battery 102 Engine 103 Generator 104 Motor 110 Engine control unit 111 Generator control unit 112 Motor control unit 113 Stationary power generation control unit 114 Charging control unit 115 Vehicle control unit

Claims

1. A hybrid vehicle including an engine, a generator driven by the engine to generate electricity, a battery that stores the electricity generated by the generator, and a control unit that performs power generation control based on a state of charge (hereinafter referred to as SOC) of the battery, The control unit: a first function of executing stationary power generation by the generator using the engine when the SOC drops to a stationary power generation start level while the vehicle is stopped, until the SOC rises to a stationary power generation end level; a second function of changing the vehicle-stop power generation end level in response to an average vehicle speed during a predetermined time immediately before the vehicle is brought into a stopped state; Hybrid vehicles, including

2. 2. The hybrid vehicle according to claim 1, wherein the control unit preliminarily sets a map that defines a direction and amount of change in the stationary power generation end level relative to the average vehicle speed, and changes the stationary power generation end level by referring to the map.

3. the control unit sets a first threshold value and a second threshold value greater than the first threshold value for the average vehicle speed, 3. The hybrid vehicle according to claim 1, wherein in the second function, if the average vehicle speed is less than the first threshold, the parked power generation end level is maintained at a normal value, if the average vehicle speed is greater than or equal to the first threshold and less than the second threshold, the parked power generation end level is lowered from the normal value by a predetermined amount, and if the average vehicle speed is greater than or equal to the second threshold, the parked power generation end level is raised from the normal value by a predetermined amount.

4. the control unit sets a first threshold value, a second threshold value that is greater than the first threshold value, and a third threshold value that is between the first threshold value and the second threshold value, for the average vehicle speed; 3. The hybrid vehicle according to claim 1, wherein in the second function, if the average vehicle speed is less than the first threshold, the stationary vehicle power generation end level is maintained at a normal value, the amount of reduction of the stationary vehicle power generation end level is gradually increased toward a predetermined value as the average vehicle speed increases between the first threshold and the third threshold, the amount of reduction of the stationary vehicle power generation end level is gradually decreased toward zero as the average vehicle speed increases between the third threshold and the second threshold, and the amount of increase of the stationary vehicle power generation end level is gradually increased as the average vehicle speed increases above the second threshold.

5. The hybrid vehicle according to claim 3 , wherein the control unit cancels the control of lowering the stationary power generation stop level when, while the vehicle is stopped, an average vehicle speed during traveling after stopping is predicted to be equal to or greater than the second threshold value.

6. The hybrid vehicle according to claim 4 , wherein the control unit cancels the control of lowering the stationary power generation stop level when, in a stationary state, it is predicted that an average vehicle speed during traveling after the vehicle is stopped will be equal to or greater than the second threshold value.

7. 3. The hybrid vehicle according to claim 1, wherein the control unit, when there is power consumption other than that for driving the vehicle, raises the stationary power generation end level by a predetermined amount according to the power consumption.

8. A method for controlling power generation while the vehicle is stopped, the method comprising: an engine; a generator driven by the engine to generate power; a battery for storing power generated by the generator; and a control unit for controlling power generation based on a state of charge (hereinafter referred to as SOC) of the battery, the method comprising: When the vehicle stops, the average vehicle speed during a predetermined period immediately prior to the stop is calculated; When the SOC is decreased to a stationary power generation start level while the vehicle is stopped, a stationary power generation end level is set in accordance with the average vehicle speed; The generator is operated by the engine to generate power while the vehicle is parked until the SOC rises from the parked power generation start level to the parked power generation end level. A method for controlling power generation while stationary.

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