JP2017094832A - Hybrid vehicle and control method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hybrid vehicle that improves fuel consumption by increasing the amount of regenerative power generation of a motor generator without giving a driver a feeling of strangeness during deceleration of the hybrid vehicle, and a control method for the same.SOLUTION: When a deceleration command C1 is issued so that a total braking force B1 can be set to be a required braking force B2 based on the deceleration command C1, a control apparatus performs control for making the total braking force B1 greater than the required braking force B2 by increasing only a regenerative braking force B5 generated by a motor generator, on the basis of a relative relationship R1 acquired by a relative relationship acquisition device.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a hybrid vehicle and a control method therefor, and more particularly, to a hybrid vehicle and a control method therefor that increase a regenerative power generation amount of a motor generator during deceleration of the hybrid vehicle and improve fuel efficiency.

  2. Description of the Related Art In recent years, a hybrid vehicle (hereinafter referred to as “HEV”) including a hybrid system having an engine and a motor generator that are controlled in combination according to the driving state of the vehicle has been attracting attention from the viewpoint of improving fuel efficiency and environmental measures. ing. In this HEV, driving force is assisted by a motor generator when the vehicle is accelerated or started, while regenerative power generation is performed by the motor generator during inertial traveling or deceleration.

  In order to efficiently increase the amount of regenerative power generation of the motor generator, cooperative regeneration is known in which the regenerative braking force of the motor generator is coordinated with the friction braking force by the brake system that applies braking force to each wheel.

  In this regard, an apparatus has been proposed that increases the amount of regenerative power generated by a motor generator in accordance with the inter-vehicle distance and relative speed from the preceding vehicle (see, for example, Patent Document 1).

  However, according to this device, the regenerative braking force by the motor generator can be increased according to the inter-vehicle distance and relative speed with the preceding vehicle without waiting for the deceleration command from the driver or the deceleration command from the control device running in the auto cruise mode. Will be generated.

  Therefore, depending on the driver, there is a problem that the driver feels uncomfortable because he / she feels unintended HEV deceleration, and drivability deteriorates.

JP 2001-054203 A

  An object of the present invention is to provide a hybrid vehicle and a control method thereof that can improve fuel efficiency by increasing the regenerative power generation amount of the motor generator without causing the driver to feel uncomfortable during deceleration of the hybrid vehicle. It is.

The hybrid vehicle of the present invention that achieves the above object includes a hybrid system having a motor generator connected to an output shaft that transmits engine power, a brake system that applies friction braking force to each wheel, the host vehicle, and a preceding vehicle. In a hybrid vehicle including a relative relationship acquisition device that acquires a relative relationship of a vehicle and a control device, a resistance braking force by an engine brake that has issued a deceleration command and stopped fuel injection of the engine, and the brake system In the case where the total braking force obtained by combining the friction braking force by the motor generator and the regenerative braking force by the motor generator or some combination thereof is set to the required braking force based on the deceleration command, the control device includes: Based on the relative relationship acquired by the relative relationship acquisition device, the motor Increasing only the regenerative braking force by the aerator, it is characterized in that the total braking force is configured to perform control of larger than the required braking force.

  In addition, the hybrid vehicle control method of the present invention that achieves the above object includes a resistance braking force by an engine brake that stops the fuel injection of the engine, a friction braking force applied to each wheel by the brake system, and a motor generator. In a hybrid vehicle control method in which braking is performed with a total braking force obtained by combining any one of the regenerative braking force or a combination of several, the total braking force is determined based on the deceleration command after the deceleration command is issued. The step of obtaining the required braking force based on the deceleration command, the step of acquiring the relative relationship with the preceding vehicle, and the regenerative braking based on the acquired relative relationship while maintaining the resistance braking force and the friction braking force. Increasing only the power to make the total braking force larger than the required braking force. A method characterized by and.

  Examples of the deceleration command include an operation command by a driver's deceleration operation and a control command of the control device in the auto cruise mode. Specifically, examples of the operation command include an accelerator-off command indicating that the accelerator pedal is turned off, a brake operation command indicating the amount of operation of the brake pedal, and the control command includes the engine in order to maintain the target vehicle speed. Examples include coasting commands for setting an idling state, brake system operation commands, and the like.

  The relative relationship between the host vehicle and the preceding vehicle is a relative relationship between the host vehicle and the preceding vehicle, and the distance between the host vehicle and the preceding vehicle and the relative speed of the preceding vehicle viewed from the host vehicle can be exemplified. .

  Increasing only the regenerative braking force by the motor generator based on this relative relationship is based on the assumption that the total braking force is maintained at the required braking force by the deceleration command, that is, the current vehicle braking force is maintained. In addition, only the regenerative braking force by the motor generator is increased so that the relative relationship does not become a close relationship.

  Note that the proximity relationship is a relationship in which the friction braking force by the brake system is expected to increase due to the proximity of the host vehicle and the preceding vehicle. That is, the fact that the relative relationship is a close relationship indicates that the distance between the host vehicle and the preceding vehicle has become shorter, or the relative speed has become negative and the preceding vehicle has approached the host vehicle.

  According to this hybrid vehicle and its control method, when the total braking force is set to the required braking force based on the deceleration command during deceleration after the deceleration command is issued, the relative relationship between the host vehicle and the preceding vehicle is set. Based on this, only the regenerative braking force of the motor generator is increased so that the total braking force is greater than the required braking force, so that the relative relationship between the host vehicle and the preceding vehicle can be appropriately maintained.

  This control causes the hybrid vehicle to decelerate more than the degree of deceleration generated by the deceleration command, but only increases the regenerative braking force of the motor generator based on the relative relationship after the deceleration command is issued. Thus, the deceleration command can give an impression that the relative relationship between the host vehicle and the preceding vehicle is properly maintained. As a result, the driver does not feel unintended deceleration, and drivability can be improved.

  Further, by this control, only the regenerative braking force of the motor generator can be increased, whereby the regenerative power generation amount of the motor generator can be increased. In addition, by converting the energy lost due to the frictional braking force by the brake system into electrical energy through regeneration, the opportunity to charge the high voltage battery using fuel can be reduced. Further, the amount of charge of the high voltage battery increases, so that the opportunity to assist with the motor generator can be increased.

  Therefore, according to the hybrid vehicle and the control method thereof, the regenerative power generation amount of the motor generator can be increased and the fuel consumption can be improved without causing the driver to feel uncomfortable during the deceleration of the hybrid vehicle.

It is a block diagram of the hybrid vehicle which consists of embodiment of this invention. It is a flowchart which illustrates the control method of the hybrid vehicle of FIG. FIG. 6 is a correlation diagram between a brake opening degree (instruction operation amount) and a required braking force. It is a correlation diagram of the gradient of a travel path and the increase / decrease amount of a request | requirement braking force. FIG. 6 is a correlation diagram between the inter-vehicle distance and the increase / decrease amount of the regenerative braking force. FIG. 5 is a correlation diagram between relative speed and the amount of increase / decrease in regenerative braking force. FIG. 5 is a correlation diagram between a deceleration command and a total braking force after increasing a regenerative braking force.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a hybrid vehicle according to an embodiment of the present invention.

  The hybrid vehicle (hereinafter referred to as “HEV”) is a vehicle including not only a normal passenger car but also a bus, a truck, a pickup truck, and the like, and an engine 10 and a motor generator that are controlled in combination according to the driving state of the vehicle. A hybrid system 30 having 31 is provided. The HEV also includes a drum brake 92 as a brake system that applies a friction braking force to each wheel. In addition, the HEV includes a relative relationship acquisition device 85 that acquires the relative relationship between the host vehicle and the preceding vehicle.

  In the engine 10, the crankshaft 13 is rotationally driven by thermal energy generated by the combustion of fuel in a plurality (four in this example) of cylinders 12 formed in the engine body 11. The engine 10 is a diesel engine or a gasoline engine. The rotational power of the crankshaft 13 is transmitted to the transmission 20 through a clutch 14 (for example, a wet multi-plate clutch) connected to one end of the crankshaft 13.

  The transmission 20 uses an AMT or an AT that automatically shifts to a target shift speed determined based on the HEV operating state and preset map data using the shift actuator 21. The transmission 20 is not limited to the automatic transmission type such as AMT, and may be a manual type in which the driver manually changes gears.

  The rotational power changed by the transmission 20 is transmitted to the differential 23 through the propeller shaft 22 and distributed to each of the pair of drive wheels 24 as drive power.

  The hybrid system 30 includes a motor generator 31, an inverter 35 that is electrically connected to the motor generator 31 in order, a high voltage battery 32 (for example, 48V), a DC / DC converter 33, and a low voltage battery 34 (for example, 12V). ).

  Preferred examples of the high voltage battery 32 include a lithium ion battery and a nickel metal hydride battery. The low voltage battery 34 is a lead battery. The DC / DC converter 33 has a function of controlling the charge / discharge direction and the output voltage between the high voltage battery 32 and the low voltage battery 34. The DC / DC converter 33 can supply power to various vehicle electrical components 36 from the high voltage battery 32 in addition to the low voltage battery 34.

  Various parameters in the high voltage battery 32 of the hybrid system 30 such as internal temperature, current value, voltage value and remaining capacity (SOC) are managed by a BMS (battery management system) 39.

  In this embodiment, the DC / DC converter 33 and the vehicle electrical component 36 are illustrated as auxiliary machines that consume the power of the high-voltage battery 32, but the auxiliary machines are electrically connected to the high-voltage battery 32. An electric air conditioner, an electric hydraulic pump, etc. can also be illustrated.

  The motor generator 31 is an endless shape wound around a first pulley 15 attached to the rotating shaft 37 and a second pulley 16 attached to the other end of the crankshaft 13 which is an output shaft of the engine body 11. Power is transmitted to and from the engine 10 via the belt-shaped member 17. Note that power can be transmitted using a gear box or the like instead of the two pulleys 15 and 16 and the belt-like member 17. Further, the output shaft of the engine main body 11 connected to the motor generator 31 is not limited to the crankshaft 13, and may be a transmission shaft or the propeller shaft 22 between the engine main body 11 and the transmission 20, for example.

  The motor generator 31 has a function of cranking instead of a starter motor (not shown) that starts the engine body 11.

  The engine 10 and the hybrid system 30 are controlled by the control device 80. Specifically, at the time of HEV start or acceleration, the hybrid system 30 assists at least a part of the driving force by the motor generator 31 supplied with power from the high voltage battery 32, while at the time of inertia traveling or braking. Performs regenerative power generation by the motor generator 31, converts surplus kinetic energy into electric power, and charges the high voltage battery 32.

  The drum brake 92 is a device that applies a friction braking force to each wheel including the drive wheels 24, and a disc brake may be used instead. Examples of the brake system using the drum brake 92 as an example include an air brake using compressed air and a hydraulic brake using hydraulic pressure.

  The relative relationship acquisition device 85 is a device that acquires the relative relationship R1 between the HEV and the preceding vehicle. Examples of the relative relationship R1 include an inter-vehicle distance L1 between the HEV and a preceding vehicle traveling on the same lane as the HEV, and a relative speed ΔV1 of the preceding vehicle as viewed from HEV. Examples of the relative relationship acquisition device 85 include a device that estimates a relative relationship from an image captured by a camera, and a device that measures a relative relationship using a millimeter wave radar, and more specifically, a lane departure prevention support system and the like. it can. The relative speed ΔV1 is the relative speed of the preceding vehicle as viewed from HEV, and the traveling direction is positive. That is, when the vehicle speed of HEV is faster than the vehicle speed of the preceding vehicle, the relative speed ΔV1 is a negative value.

  In such HEV, when the deceleration command C1 is issued and the total braking force B1 is set to the required braking force B2 based on the deceleration command C1, the control device 80 acquires the relative relationship acquired by the relative relationship acquisition device 85. Based on R1, only the regenerative braking force B5 by the motor generator 31 is increased, and the total braking force B1 is controlled to be larger than the required braking force B2.

The control device 80 includes a CPU that performs various processes, an internal storage device that can read and write programs and processing results used to perform the various processes, and various interfaces.

  The control device 80 is connected to the hybrid system 30 (the engine 10 and the inverter 35), the drum brake 92, and the relative relationship acquisition device 85 via signal lines. The control device 80 also includes an accelerator opening sensor 96 that detects the amount of depression of the accelerator pedal 95 (accelerator opening) via a signal line, and a brake opening that detects the amount of depression of the brake pedal 90 (brake opening). The sensor 97 is connected to a vehicle speed sensor 99 that detects the vehicle speed V1.

  In the control device 80, a plurality of execution programs are stored in the internal storage device. As the execution programs, a program for changing the total braking force B1 to the required braking force B2 based on the deceleration command C1, and a relative relationship R1. A program for increasing the regenerative braking force B5 by the motor generator 31 can be exemplified.

  Next, the HEV control method in which the above program is executed will be described below as a function of the control device 80 with reference to the flowchart of FIG. This control method is assumed to be triggered by the fact that the deceleration command C1 is started while the HEV is running.

  First, in step S10, the control device 80 receives a deceleration command C1. Examples of the deceleration command C1 include an operation command by the driver's deceleration operation and a control command of the control device 80 in the auto cruise mode.

  Specifically, as an operation command by the driver's deceleration operation, an accelerator off command C2 indicating that the accelerator pedal 95 of the accelerator opening sensor 96 is turned off, or a brake indicating an operation amount of the brake pedal 90 of the brake opening sensor 97 is displayed. An operation command C3 can be exemplified. Further, examples of the control command include a coasting command C4 for setting the engine 10 in an idling state on a downhill road to maintain the target vehicle speed, a brake operation command C5 for the drum brake 92 when the vehicle speed exceeds the target vehicle speed, and the like. In addition, when the engine 10 includes an auxiliary brake such as an exhaust brake or a compression release brake, an operation command thereof can be exemplified.

  The auto-cruise mode is used especially when traveling on a highway, and the program stored in the control device 80 automatically schedules HEV when an unillustrated auto-cruise switch is turned on by the driver. It is a mode that runs on the street.

  In this auto-cruise mode, engine travel, assist travel, motor travel, and inertia travel are selected in a timely manner based on parameters such as the gradient of the travel path and the weight of the HEV, and the HEV vehicle speed is set in advance. Examples include a mode in which the HEV is automatically driven while maintaining the speed range, and a mode in which the HEV is made to follow the preceding vehicle by appropriately selecting to follow the preceding vehicle.

  Next, in step S20, the control device 80 calculates the required braking force B2 based on the deceleration command C1. Specifically, the required braking force B2 is calculated with reference to map data that has been created in advance through experiments and tests and stored in the internal storage device using the deceleration command C1 as a parameter.

  For example, when the accelerator-off command C2 and the coasting command C4 are received in step S10, the required braking force B2 is set to a braking force corresponding to the engine brake according to the HEV vehicle speed. Further, when the brake operation command C3 or the brake operation command C5 is received in step S10, the braking force is set according to the brake opening degree or the instructed instruction operation amount.

  FIG. 3 is map data illustrating the correlation between the brake opening (instructed operation amount) and the required braking force B2. As shown in FIG. 3, the brake opening degree (instructed operation amount) and the required braking force B2 have a positive correlation.

  In this step S20, the required braking force B2 may be increased or decreased in accordance with the HEV vehicle weight or the traveling road gradient. Specifically, the vehicle weight and the gradient are acquired as parameters, and the increase / decrease amount of the required braking force B2 is calculated with reference to map data that is created in advance by experiments and tests and stored in the internal storage device.

  FIG. 4 is map data illustrating the correlation between the gradient of the traveling road and the increase amount of the required braking force B2 when the vehicle weight is a predetermined value. In the drawing, the solid line is set to a predetermined vehicle weight M1, the dotted line is set to a vehicle weight M2 that is lighter than the vehicle weight M1, and the alternate long and short dash line is set to a vehicle weight M3 that is heavier than the vehicle weight M1. As shown in FIG. 4, the vehicle weight and the increase amount thereof, and the gradient and the increase amount thereof have a positive correlation at a balance gradient θ or more.

  The balance gradient θ is based on the HEV vehicle weight, and has a negative correlation with the vehicle weight. As the vehicle weight increases, the balance gradient θ decreases. The balance gradient θ is a gradient in which the forward speed due to the gravitational acceleration applied to the HEV is equal to or greater than the running resistance, and the vehicle speed V1 does not decelerate even if the driving force of the engine 10 and the motor generator 31 is not applied. As the balance gradient θ, for example, when the vehicle weight of HEV is 25 t, a gradient of 2% can be exemplified.

  In addition, especially when the HEV is a vehicle such as a bus, a truck, or a pickup truck, the vehicle weight varies greatly depending on the load and the number of passengers. Therefore, a balance gradient θ and an increase amount corresponding to the vehicle weight should be set. Is desirable.

  By performing such control, when the vehicle weight is relatively heavy, the amount of regenerative electric power of the motor generator 31 can be increased, which is advantageous in improving fuel consumption. Further, when the vehicle weight is relatively light, it is possible to avoid that the hybrid vehicle is excessively decelerated due to excessive braking force due to regeneration, which is advantageous in improving drivability.

  As a means for acquiring the HEV vehicle weight, a program for estimating the vehicle weight on the assumption that the driving force transmitted to the drive wheels 24 at the time of starting or shifting is equal to the running resistance can be exemplified. In addition, as means for acquiring the gradient of the traveling road, a program that is calculated based on detection values of various sensors such as an acceleration sensor (G sensor), a wheel speed sensor, and a gyro sensor (not shown) and a navigation system (not shown) are registered. An example of a program that refers to current gradient information.

  Next, in step S30, the control device 80 performs control to change the total braking force B1 to the required braking force B2. The total braking force B1 is any one or some of a resistance braking force B3 by the engine brake that stops the fuel injection of the engine 10, a friction braking force B4 by the drum brake 92, and a regenerative braking force B5 by the motor generator 31. This is the total braking force. The total braking force B1 may include braking force by an auxiliary brake such as an exhaust brake, a compression release brake, and a retarder.

In this step S30, for example, when the accelerator off command C2 or the coasting command C4 is received in step S10, the regenerative braking force B5 is added to the resistance braking force B3 when the gradient of the travel path is larger than the balancing gradient θ. Thus, the total braking force B1 is set to the required braking force B2. Further, when the brake operation command C3 or the brake operation command C5 is received in step S10, the friction braking force B4 corresponding to the brake opening degree (instructed operation amount) is added to the resistance braking force B3, and the total braking force B1 is obtained as the required braking force. Set to B2. When the HEV brake system is equipped with a cooperative regeneration system, the regenerative braking force B5 is added to the resistance braking force B3, and the friction braking force B4 corresponding to the difference between them and the required braking force B2 is added. The braking force B1 is set to the required braking force B2.

  Next, in step S40, the relative relationship acquisition device 85 acquires the relative relationship R1 between the HEV and the preceding vehicle.

  Next, in step S50, the control device 80 determines whether or not a condition is satisfied. This condition is established when the relative relationship R1 becomes the proximity relationship R2 where the friction braking force B4 by the drum brake 92 is expected to increase, assuming that the total braking force B1 is maintained at the required braking force B2.

  The proximity relationship R2 is a relationship in which the friction braking force B4 by the drum brake 92 is expected to increase as the HEV and the preceding vehicle approach each other. Examples of the proximity relationship R2 include a relationship in which the inter-vehicle distance L1 between the HEV and the preceding vehicle becomes the proximity distance L2, or the relative speed ΔV1 between the HEV and the preceding vehicle becomes the proximity speed ΔV2.

  The proximity distance L2 is set according to the HEV vehicle speed V1, and when the vehicle speed V1 is 60 km / h or less, a distance obtained by subtracting a predetermined value from the value of the vehicle speed V1 (for example, the vehicle speed is 40 km / h, the predetermined speed). When the vehicle speed V1 exceeds 60 km / h, the proximity distance L2 is approximately the same as the vehicle speed V1 (for example, the vehicle speed is 80 km / h). Can be exemplified by 80 km).

  An example of the proximity speed ΔV2 is −10 km / h or less when the inter-vehicle distance L1 is equal to or less than the proximity distance L2. The proximity speed ΔV2 is preferably increased or decreased according to the inter-vehicle distance L1. For example, the proximity speed ΔV2 is decreased (approached to zero) each time the inter-vehicle distance L1 is equal to or smaller than the proximity distance L2 and the inter-vehicle distance L1 is reduced.

  If it is determined in step S50 that the condition is not satisfied, the process returns to the start. On the other hand, when the condition is satisfied, that is, when it is determined that the relative relationship R1 becomes the proximity relationship R2 when the total braking force B1 is maintained in the current state, the process proceeds to step S60.

  Next, in step S60, the control device 80 calculates the increase amount ΔB of the regenerative braking force B5 by the motor generator 31. Specifically, the increase amount ΔB is calculated with reference to map data that has been created in advance through experiments and tests using the vehicle speed V1, the inter-vehicle distance L1, and the relative speed ΔV1 as parameters, and stored in the internal storage device.

  FIG. 5 is map data illustrating the relationship between the inter-vehicle distance L1 and the increase amount ΔB when the vehicle speed V1 is a predetermined speed. FIG. 6 is map data illustrating the relationship between the relative speed ΔV1 and the increase amount ΔB when the inter-vehicle distance L1 is equal to or less than the proximity distance L2.

  As described above, the vehicle speed V1 and the inter-vehicle distance L1 have a positive correlation. According to these map data, the inter-vehicle distance L1 and the increase amount ΔB have a negative correlation, and the relative speed ΔV1 and the increase amount ΔB. And negative correlation.

  Next, in step S70, the control device 80 increases the regenerative braking force B5 of the motor generator 31 by the calculated increase amount ΔB. When step S70 is completed, the process returns to the start, and steps S10 to S70 are repeated until the HEV travel stops.

  FIG. 7 illustrates the relationship between each deceleration command C1 and the total braking force B1 after increasing the regenerative braking force B5.

  As shown in FIG. 7, by performing the above control, when it is determined that the relative relationship R1 between the HEV and the preceding vehicle becomes the proximity relationship R2 during deceleration after the deceleration command C1 is issued, the motor Only the regenerative braking force B5 of the generator 31 increases, and the total braking force B1 becomes larger than the required braking force B2. Then, by the increase in the regenerative braking force B5, the relative relationship R1 between the HEV and the preceding vehicle can be appropriately maintained so as not to become the proximity relationship R2.

  By this control, the HEV is decelerated more than the degree of deceleration generated by the deceleration command C1, but after the deceleration command C1 is issued, only the regenerative braking force B5 of the motor generator 31 is increased based on the relative relationship R1. By doing so, the deceleration command C1 can give an impression that the relative relationship R1 between the HEV and the preceding vehicle is appropriately maintained so as not to become the proximity relationship R2. As a result, the driver does not feel unintended deceleration, and drivability can be improved.

  Further, the regenerative power generation amount of the motor generator 31 can be increased by increasing only the regenerative braking force B5 of the motor generator 31. In addition, when the relative relationship R1 between the HEV and the preceding vehicle becomes the proximity relationship R2, the energy lost due to the friction braking force B4 by the drum brake 92 is converted into electric energy by amendment, so that high fuel is used. Opportunities for charging the voltage battery 32 can be reduced. Furthermore, since the amount of charge of the high voltage battery 32 increases, the opportunity to assist the motor generator 31 can be increased.

  From these results, according to the HEV described above, the regenerative power generation amount of the motor generator 31 can be increased without causing the driver to feel uncomfortable during the deceleration of the HEV, so that the fuel consumption can be improved.

  In the above-described control method, the regenerative braking force B5 by the motor generator 31 can be increased even in an HEV that does not have a coordinated regenerative system that is complicated in control and high in cost. The amount can be increased.

DESCRIPTION OF SYMBOLS 10 Engine 30 Hybrid system 31 Motor generator 80 Control apparatus 85 Relative relationship acquisition apparatus 92 Drum brake (brake system)
B1 Total braking force B2 Required braking force B3 Resistance braking force B4 Friction braking force B5 Regenerative braking force C1 Deceleration command R1 Relative relationship

Claims (3)

A hybrid system having a motor generator connected to an output shaft for transmitting engine power; a brake system for applying friction braking force to each wheel; and a relative relationship acquisition device for acquiring a relative relationship between the host vehicle and a preceding vehicle; A hybrid vehicle comprising a control device,
Any one or some combination of a resistance braking force by an engine brake that has issued a deceleration command and stopped fuel injection of the engine, a friction braking force by the brake system, and a regenerative braking force by the motor generator When the total braking force combined is a required braking force based on the deceleration command,
The control device performs control to increase only the regenerative braking force by the motor generator based on the relative relationship acquired by the relative relationship acquisition device and to make the total braking force larger than the required braking force. A hybrid vehicle characterized by being configured as described above.   When the control device assumes that the total braking force is maintained at the required braking force, the relative relationship becomes a proximity relationship where the friction braking force by the brake system is expected to increase. The hybrid vehicle according to claim 1, wherein only the regenerative braking force by the motor generator is increased. Comprehensive synthesis of either one or some combination of the resistance braking force by the engine brake that stopped the fuel injection of the engine, the friction braking force applied to each wheel by the brake system, and the regenerative braking force by the motor generator In a control method of a hybrid vehicle that brakes by a braking force,
After the deceleration command is issued,
Based on the deceleration command, the step of making the total braking force a required braking force based on the deceleration command;
Obtaining a relative relationship with the preceding vehicle;
Maintaining the resistance braking force and the friction braking force, and increasing only the regenerative braking force based on the acquired relative relationship to make the total braking force larger than the required braking force. A control method of a hybrid vehicle characterized by the above.