# US 12,109,913 B2 · Regenerative braking system using reference deceleration during vehicle coasting drive and method thereof

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- Number: US 12,109,913 B2
- Document ID: US12109913B2
- Status: Granted
- Kind: B2
- Application number: 17/409,219
- Filed: 2021-08-23
- Published: 2022-04-14
- Granted: 2024-10-08
- Earliest claimed: 2020-10-08
- Assignees: Hyundai Motor Company; Kia Corporation
- Applicants: Hyundai Motor Company; Kia Corporation
- Inventors: Gyu-Bin Sim; Kyung-Han Min; Seung-Jae Yoo; A-Ram Park
- Web page: https://patentgrep.com/patent/US12109913B2

## CPC

- B60L 3/0015: {Prevention of collisions}
- B60L 7/18: Controlling the braking effect (B60L7/12, B60L7/14, B60L7/16 take precedence)
- B60L 15/2009: {for braking}
- B60L 2240/12: Speed
- B60L 2240/16: longitudinal
- B60L 2240/423: Torque
- B60L 2240/68: Traffic data
- B60L 2250/28: Accelerator pedal thresholds
- B60L 2260/24: Coasting mode
- Y02T 10/60: Other road transportation technologies with climate change mitigation effect
- Y02T 10/64: Electric machine technologies in electromobility
- Y02T 10/72: Electric energy management in electromobility
- B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

A regenerative braking system is provided. The regenerative braking system includes: a preceding vehicle recognition module installed in a vehicle, the preceding vehicle recognition module configured to determine whether a preceding vehicle is present and measure information on a relative distance and a relative velocity to the preceding vehicle; a vehicle sensor installed in the vehicle; and a controller configured to receive information generated from the preceding vehicle recognition module and a sensor signal generated form the vehicle sensor; to generate a reference deceleration to maintain a distance from the preceding vehicle within a safety distance; to generate a driving torque command for outputting regenerative braking torque for following the generated reference deceleration; and to transfer the generated driving torque command to a vehicular driving system.

## Claims

### Claim 1

A regenerative braking system of a vehicle, comprising:
a preceding vehicle recognition module installed in a vehicle, the preceding vehicle recognition module configured to determine whether a preceding vehicle is present and measure information on a relative distance and a relative velocity to the preceding vehicle;
a vehicle sensor installed in the vehicle; and
a controller configured to:
receive information generated from the preceding vehicle recognition module and a sensor signal generated form the vehicle sensor;
generate a reference deceleration (a_ref) to maintain a distance from the preceding vehicle within a safety distance, wherein the reference deceleration (a_ref) is generated based on a constant acceleration model acceleration value (a_ca);
generate a driving torque command for outputting regenerative braking torque for following the generated reference deceleration; and
transfer the generated driving torque command to a vehicular driving system;
wherein the vehicular driving system is configured to receive the driving torque command and to apply regenerative braking torque to a motor of a vehicle according to the driving torque command;
wherein the controller further comprises,
a deceleration requirement determining unit configured to:
determine whether regenerative braking actuation is required according to a sensor signal input from the vehicle sensor; and
when it is determined that the regenerative braking actuation is required, determine whether deceleration of the vehicle is required according to information of the preceding vehicle input from the preceding vehicle recognition module;
a reference deceleration generating unit configured to:
when it is determined that the deceleration of the vehicle is required, generate the reference deceleration (a_ref) depending on a driving situation of the vehicle by using the information of the preceding vehicle input from the preceding vehicle recognition module and the sensor signal input from the vehicle sensor; and
a driving torque amount generating unit configured to:
generate a driving torque command to allow the vehicle to follow the reference deceleration (a_ref) generated by the reference deceleration generating unit; and
transfer the generated driving torque command to the vehicular driving system;
wherein the reference deceleration generating unit is further configured to:
generate the reference deceleration (a_ref) depending on a driving situation of the user vehicle according to the information of the relative distance and the relative velocity between the user vehicle and the preceding vehicle, and velocities and acceleration sensor signals of the user vehicle and the preceding vehicle, respectively; and
calculate the constant acceleration model acceleration value (a_ca) by using a constant acceleration (CA) model based on the information of the relative distance and the relative speed, and the sensor signals of the speed and the acceleration; and
calculate a CTG policy model acceleration value (a_ctg) by using a constant time gap (CTG) policy model based on the information of the relative distance and the relative speed, and the sensor signals of the speed and the acceleration.

### Claim 2 (depends on 1)

The regenerative braking system of claim 1, wherein the deceleration requirement determining unit is configured to:
determine whether the regenerative braking actuation is required according to an input value of an accelerator pedal sensor (ASP) in the vehicle sensor; and
receive, from the preceding vehicle recognition module, information of a relative distance and a relative velocity between a user vehicle and the preceding vehicle to determine whether the deceleration of the vehicle is required.

### Claim 3 (depends on 1)

The regenerative braking system of claim 1, wherein the reference deceleration generation unit is configured to:
calculate the constant acceleration model acceleration value (a_ca) by using Equation 1
(
Equation
⁢
1
)
a
CA
=
v
pre
2
-
v
ego
2
2
⁢
d
,
(
1
)
wherein v_ego is a velocity of the user vehicle, v_pre is a velocity of the preceding vehicle, and dis information on a distance between the user vehicle and the preceding vehicle.

### Claim 4 (depends on 1)

The regenerative braking system of claim 1, wherein the reference deceleration generation unit is configured to:
calculate the CTG policy model acceleration value (a_ctg) by Equation 7
(
Equation
⁢
7
)
a
CTG
=
-
1
h
⁢
(
ε
.
+
λ
⁢
δ
)
,
(
7
)
wherein λ is a tuning parameter and when the value of λ is larger, the relative distance converges to the safety distance faster.

### Claim 5 (depends on 1)

The regenerative braking system of claim 1, wherein the reference deceleration generation unit is configured to:
calculate the CTG policy model acceleration value (a_ctg) by Equation 8,
(
Equation
⁢
8
)
a
CTG
=
-
1
h
⁢
(
v
rel
+
λ
⁢
δ
)
,
(
8
)
wherein v_rel is relative velocities of user vehicle and preceding vehicle.

### Claim 6 (depends on 1)

The regenerative braking system of claim 1, wherein the reference deceleration generation unit is configured to:
calculate the reference deceleration (a_ref) by Equations 9 and 10
(Equation 9)
aref=wCAaCA+wCTGaCTG (9)
wherein w_ca is weight of the constant acceleration model acceleration value (a_ca), and w_ctg is weight of the CTG policy model acceleration value (a_ctg)
(Equation 10)
wCTG=1−wCA (10).

### Claim 7

A regenerative braking method performed by a preceding vehicle recognition module, a vehicle sensor, and a controller installed in a vehicle, comprising:
monitoring, by the controller, a signal input from an accelerator pedal sensor (APS) of the vehicle sensor;
when the signal is monitored, determining, by the controller, whether a value of a sensor signal of the APS is less than a predetermined first reference value to determine whether a user vehicle is being accelerated by stepping on an accelerator pedal;
when it is determined that the value of the sensor signal of the APS is less than the first reference value and the user vehicle is in a coasting driving, monitoring, by the controller, information of the preceding vehicle input from the preceding vehicle recognition module;
determining whether the relative speed between the user vehicle and the preceding vehicle is less than 0 to determine whether deceleration of the user vehicle is required;
when it is determined that the deceleration of the user vehicle is required, generating, by the controller, a reference deceleration (a_ref) to maintain a distance from the preceding vehicle within a safety distance by using information of the preceding vehicle input from the preceding vehicle recognition module and a sensor signal input from the vehicle sensor, wherein the reference deceleration (a_ref) is generated based on a constant acceleration model acceleration value (a_ca);
generating, by the controller, a driving torque command for outputting regenerative braking torque for following the generated reference deceleration; and
transferring the generated driving torque command to a vehicular driving system, wherein the vehicle driving system is configured to receive the driving torque command and to apply regenerative braking torque to a motor of a vehicle according to the driving torque command:
wherein generating the reference deceleration (a_ref) includes:
generating the reference deceleration (a_ref) depending on a driving situation of the user vehicle according to the information of the relative distance and the relative velocity between the user vehicle and the preceding vehicle, and velocities and acceleration sensor signals of the user vehicle and the preceding vehicle, respectively;
calculating the constant acceleration model acceleration value (a_ca) by using a constant acceleration (CA) model based on the information of the relative distance and the relative speed, and the sensor signals of the speed and the acceleration; and
calculating a CTG policy model acceleration value (a_ctg) by using a constant time gap (CTG) policy model based on the information of the relative distance and the relative speed, and the sensor signals of the speed and the acceleration.