# US 9,517,698 B2 · System and method for power management during regeneration mode in hybrid electric vehicles

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- Number: US 9,517,698 B2
- Document ID: US9517698B2
- Status: Granted
- Kind: B2
- Application number: 15/071,521
- Filed: 2016-03-16
- Published: 2016-07-07
- Granted: 2016-12-13
- Earliest claimed: 2013-03-14
- Assignees: Allison Transmission, Inc.
- Applicants: Allison Transmission, Inc.
- Inventors: Jeffrey K. Runde; Stephen T. West
- Web page: https://patentgrep.com/patent/US9517698B2

## CPC

- B60L 7/10: Dynamic electric regenerative braking (B60L7/22 takes precedence)
- B60K 6/26: characterised by the motors or the generators
- B60L 3/12: Recording operating variables {; Monitoring of operating variables}
- B60L 15/2009: {for braking}
- B60W 10/06: including control of combustion engines
- B60W 10/08: including control of electric propulsion units, e.g. motors or generators
- B60W 10/18: including control of braking systems
- B60W 10/26: for electrical energy, e.g. batteries or capacitors
- B60W 20/00: Control systems specially adapted for hybrid vehicles {(hybrid vehicle design, B60K6/00; electric vehicles B60L)}
- B60W 20/11: using model predictive control [MPC] strategies, i.e. control methods based on models predicting performance {(utilising navigation and traffic information in the control strategy B60W20/12)}
- B60W 20/14: in conjunction with braking regeneration
- B60W 30/18127: {Regenerative braking}
- B60W 40/12: related to parameters of the vehicle itself {, e.g. tyre models}
- B60W 50/0097: {Predicting future conditions}
- B60W 40/1005: {Driving resistance}
- B60W 2400/00: Indexing codes relating to detected, measured or calculated conditions or factors
- B60W 2510/1095: Inertia
- B60W 2520/105: Longitudinal acceleration
- B60W 2530/16: Driving resistance
- B60W 2540/10: Accelerator pedal position
- B60W 2540/12: Brake pedal position
- B60W 2710/08: Electric propulsion units
- B60W 2710/086: Power
- B60W 2710/18: Braking system
- B60Y 2200/92: Hybrid vehicles
- B60Y 2300/60: Control of electric machines, e.g. problems related to electric motors or generators
- B60Y 2300/64: Drag run or drag torque compensation, e.g. motor to drive engine with drag torque or engine speed is brought to start speed before injection and firing
- B60Y 2300/91: Battery charging
- Y02T 10/62: Hybrid vehicles
- Y02T 10/72: Electric energy management in electromobility
- Y02T 10/92: Energy efficient charging or discharging systems for batteries, ultracapacitors, supercapacitors or double-layer capacitors specially adapted for vehicles
- Y10S 903/906: Motor or generator
- Y10S 903/93: Conjoint control of different elements
- Y10S 903/947: Characterized by control of braking, e.g. blending of regeneration, friction braking
- 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
- B60K: ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
- B60W: CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60Y: INDEXING SCHEME RELATING TO ASPECTS CROSS-CUTTING VEHICLE TECHNOLOGY
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

A system and method for recovering the optimum power level during regenerative mode is disclosed. Equations for determining the optimum regenerative power level receivable by an energy storage system, for example for any given deceleration event, are derived and disclosed. The equations consider various losses such as the efficiency of the electric motor generator in the generator mode, wind resistance, rolling resistance, transmission losses, engine losses, and losses in the energy storage system. Also disclosed is at least one embodiment of a procedure for controlling a hybrid drive system to achieve the optimum energy recovery.

## Claims

### Claim 1

A method of controlling regenerative braking in a hybrid electric vehicle, comprising:
calculating a predicted vehicle energy loss for a vehicle using a vehicle controller, wherein the vehicle has an electric motor generator and an energy storage system, and wherein the electric motor generator is electrically connected to the energy storage system;
calculating an expected electric motor operating efficiency using the vehicle controller;
calculating a predicted electrical power to supply to the energy storage system using the vehicle controller and the predicted vehicle energy loss; and
generating a regenerative braking power using the electric motor generator operating as a generator, wherein the regenerative braking power is less than or equal to the predicted electrical power to supply to the energy storage system.

### Claim 2 (depends on 1)

The method of claim 1, further comprising detecting a deceleration state of the vehicle.

### Claim 3 (depends on 2)

The method of claim 2, wherein the act of detecting a deceleration state includes detecting a torque provided from a transmission to the electric motor generator, wherein the electric motor generator is coupled to the transmission.

### Claim 4 (depends on 1)

The method of claim 1, wherein the predicted vehicle energy loss includes losses caused by an expected change in vehicle kinetic energy.

### Claim 5 (depends on 1)

The method of claim 1, wherein the predicted electrical power to supply to the energy storage system includes a predicted electrical power loss resulting from an expected transfer of the predicted electrical power to the energy storage system.

### Claim 6 (depends on 1)

The method of claim 1, wherein the act of calculating the predicted vehicle energy loss includes calculating an engine energy loss.

### Claim 7 (depends on 6)

The method of claim 6, wherein the act of calculating the engine energy loss includes calculating an engine compression force loss.

### Claim 8 (depends on 6)

The method of claim 6, wherein the act of calculating the engine energy loss includes calculating an engine frictional force loss.

### Claim 9 (depends on 1)

The method of claim 1, wherein the act of calculating the predicted vehicle energy loss includes calculating a wind resistance loss, wherein the wind resistance loss is calculated by the vehicle controller using a vehicle velocity and a vehicle aerodynamic coefficient.

### Claim 10 (depends on 1)

The method of claim 1, wherein the act of calculating the predicted vehicle energy loss includes calculating a rolling resistance loss, wherein the rolling resistance loss is calculated by the vehicle controller using a vehicle mass, a vehicle velocity, and a vehicle rolling resistance coefficient.

### Claim 11 (depends on 1)

The method of claim 1, wherein the act of calculating the predicted vehicle energy loss includes calculating a vehicle transmission loss.

### Claim 12 (depends on 11)

The method of claim 11, wherein the vehicle transmission loss is calculated using a transmission inertia loss and a transmission friction loss.

### Claim 13 (depends on 1)

The method of claim 1, wherein the act of calculating the predicted vehicle energy loss includes calculating an accessory loss.

### Claim 14 (depends on 1)

The method of claim 1, wherein the act of calculating the expected electric motor operating efficiency includes accessing a previous vehicle activity stored in a memory in the vehicle controller and calculating the expected electric motor operating efficiency based on the previous vehicle activity.

### Claim 15 (depends on 1)

The method of claim 1, wherein the act of calculating the expected electric motor operating efficiency is calculated using an electric motor speed and an electric motor torque.

### Claim 16 (depends on 5)

The method of claim 5 wherein the predicted electrical power loss can be calculated by the equation:
P
heat
=
R
ESS
⁡
(
P
ESS
V
ESS
)
2
wherein:
Pheat is the predicted electrical power loss,
RESS is a resistance of the energy storage system,
PESS is the predicted electrical power to supply to the energy storage system, and
VESS is a voltage supplied to the energy storage system.

### Claim 17 (depends on 1)

The method of claim 1, wherein the predicted electrical power to supply to the energy storage system can be calculated by the equation:
P
ESS
=
efficiency
*
P
Loss
⁡
[
-
1
+
1
+
V
regen
2
efficiency
*
P
Loss
*
R
ESS
]
wherein:
PESS is the predicted electrical power to supply to the energy storage system,
efficiency is the expected electrical motor operating efficiency,
PLoss is a power loss resulting from a predicted vehicle kinetic energy change,
RESS is a resistance of the energy storage system, and
Vregen is a voltage supplied to the energy storage system from the electric motor generator operating in the generator mode.

### Claim 18 (depends on 1)

The method of claim 1, wherein the energy storage system includes one or more battery cells.

### Claim 19 (depends on 2)

The method of claim 2, wherein the act of detecting a deceleration event includes detecting a zero input signal on a brake pedal, and a zero input signal on an accelerator pedal.

### Claim 20

A method of calculating regenerative braking power, comprising:
calculating a predicted vehicle energy loss using a vehicle controller in a vehicle having a hybrid system that includes an electric motor generator, an internal combustion engine, and an energy storage system, the vehicle controller calculating the predicted vehicle energy loss using a current rate of deceleration of the vehicle;
calculating a predicted electrical power supplied to the energy storage system using the vehicle controller, the vehicle controller calculating the predicted electrical power using the predicted vehicle energy loss;
calculating a predicted electrical power loss using the vehicle controller, the vehicle controller calculating the electrical power loss using the predicted electrical power supplied to the energy storage system;
calculating a predicted regenerative braking power using the vehicle controller, the vehicle controller calculating the predicted regenerative braking power using the predicted vehicle energy loss, the predicted electrical power supplied to the energy storage system, and the predicted electrical power loss;
controlling the electric motor generator to generate a regenerative braking power using the controller, the electric motor operating in a generator mode to generate a regenerative braking power that is less than or equal to the predicted regenerative braking power.

### Claim 21 (depends on 20)

The method of claim 20, further comprising calculating an expected electric motor operating efficiency using the vehicle controller.

### Claim 22 (depends on 21)

The method of claim 21, wherein the act of calculating the expected electric motor operating efficiency includes accessing one or more previous electric motor operating efficiency values stored in a memory in the vehicle controller and using the vehicle controller to calculate the expected electric motor operating efficiency using the one or more previous electric motor operating efficiency values.

### Claim 23 (depends on 21)

The method of claim 21, wherein the act of calculating the expected electric motor operating efficiency is calculated by the vehicle controller using an electric motor speed and an electric motor torque.

### Claim 24 (depends on 20)

The method claim 20, wherein the act of calculating the predicted electrical power loss includes calculating a predicted change in the temperature of one or more components within the energy storage system.

### Claim 25 (depends on 20)

The method claim 20, wherein the act of calculating the predicted vehicle energy loss includes calculating a wind resistance loss, wherein the wind resistance loss is calculated by the vehicle controller using a vehicle speed and a vehicle aerodynamic coefficient.

### Claim 26 (depends on 20)

The method claim 20, wherein the act of calculating the vehicle energy loss includes calculating a rolling resistance loss, wherein the rolling resistance loss is calculated by the vehicle controller using a vehicle mass, a vehicle speed, and a vehicle rolling resistance coefficient.

### Claim 27 (depends on 20)

The method claim 20, further comprising detecting a deceleration state.

### Claim 28 (depends on 27)

The method of claim 27, wherein the act of detecting a deceleration state further comprises using the vehicle controller to detect a torque provided from a transmission to the electric motor generator, wherein the electric motor generator is coupled to the transmission.

### Claim 29 (depends on 27)

The method of claim 27, wherein the act of detecting a deceleration state further comprises using the vehicle controller to detect a brake pedal input signal, and an accelerator pedal input signal.

### Claim 30 (depends on 20)

The method of claim 20, wherein the act of calculating the predicted vehicle energy loss includes using the controller to calculate an engine energy loss.

### Claim 31 (depends on 30)

The method of claim 30, wherein the act of calculating the engine energy loss includes using the vehicle controller to calculate an engine compression force loss.

### Claim 32 (depends on 30)

The method of claim 30, wherein the act of calculating the engine energy loss includes using the vehicle controller to calculate an engine frictional force loss.

### Claim 33 (depends on 20)

The method of claim 20, wherein the hybrid system includes a transmission coupled to the electric motor generator, and wherein the act of calculating the vehicle energy loss includes using the vehicle controller to calculate a vehicle transmission loss.

### Claim 34 (depends on 33)

The method of claim 33, wherein the vehicle transmission loss is calculated by the vehicle controller using a transmission inertia resistance and a transmission friction resistance.

### Claim 35

A drive system for a hybrid vehicle comprising:
an energy storage system;
a vehicle drive train including an electric motor generator electrically connected to the energy storage system;
a vehicle controller coupled to the energy storage system and the electric motor generator, the vehicle controller having a memory coupled to a processor, the processor configured to:
detect a deceleration state of the hybrid vehicle;
calculate a predicted vehicle kinetic energy change resulting from one or more vehicle energy losses;
calculate a predicted electrical energy loss resulting from an expected transfer of a predicted electrical energy to the energy storage system;
calculate an expected electric motor operating efficiency;
calculate a predicted maximum electrical power deliverable into the energy storage system based on the predicted vehicle kinetic energy change, the predicted electrical energy loss, and the predicted motor operating efficiency; and
operate the electric motor generator in an electric generator mode to generate a generated energy that is substantially equal to the predicted maximum electrical power.