# US 2015/0149014 A1 · Method of controlling a mild hybrid electric vehicle

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- Number: US 2015/0149014 A1
- Document ID: US20150149014A1
- Status: Published application
- Kind: A1
- Application number: 14/542,044
- Filed: 2014-11-14
- Published: 2015-05-28
- Earliest claimed: 2013-11-26
- Assignees: Ford Global Technologies, LLC
- Applicants: Ford Global Technologies, LLC
- Inventors: Donatus Andreas Josephine KEES; Cayetano David Fuente SAN JUAN
- Web page: https://patentgrep.com/patent/US20150149014A1

## CPC

- B60L 58/12: responding to state of charge [SoC]
- B60L 1/00: Supplying electric power to auxiliary equipment of vehicles (circuit arrangements for charging batteries H02J7/00)
- B60L 1/12: Methods and devices for control or regulation
- B60L 15/2045: {for optimising the use of energy}
- B60L 50/16: with provision for separate direct mechanical propulsion
- B60L 58/10: for monitoring or controlling batteries
- B60L 58/20: having different nominal voltages
- H02J 7/1423: {with multiple batteries}
- H02J 7/1438: {in combination with power supplies for loads other than batteries}
- H02J 7/1446: {in response to parameters of a vehicle}
- H02J 7/34: Parallel operation in networks using both storage and other DC sources, e.g. providing buffering (H02J7/14 takes precedence)
- H02J 7/342: {The other DC source being a battery actively interacting with the first one, i.e. battery to battery charging (with circuits for polarity protection H02J7/68)}
- B60K 6/485: Motor-assist type
- B60L 2210/10: DC to DC converters
- B60L 2240/44: related to combustion engines
- B60L 2240/526: Operating parameters
- B60L 2240/547: Voltage
- B60W 20/40: Controlling the engagement or disengagement of prime movers, e.g. for transition between prime movers {(power-up or power-down of the driveline B60W30/192)}
- H02J 1/082: DC supplies with two or more different DC voltage levels
- H02J 2105/37: exchanging power with electric vehicles [EV] or with hybrid electric vehicles [HEV]
- Y02T 10/62: Hybrid vehicles
- Y02T 10/64: Electric machine technologies in electromobility
- Y02T 10/70: Energy storage systems for electromobility, e.g. batteries
- Y02T 10/7072: Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
- 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 903/903: having energy storing means, e.g. battery, capacitor
- Y10S 903/93: Conjoint control of different elements
- 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
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- 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
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

A method is disclosed for controlling the operation of a mild hybrid electric vehicle having an engine and high and low voltage power systems selectively connectable via a DC to DC converter. The method comprises whenever possible using only a low voltage battery forming part of the low voltage power system to power low voltage loads during an engine E-stop performed automatically to save fuel and reduce emissions and whenever possible using only a high voltage battery forming part of the high voltage power system to recharge the low voltage battery when the engine is restarted following the E-stop.

## Claims

### Claim 1

A method of controlling a mild hybrid electric vehicle comprising:
in response to an automatic engine stop, using a low voltage battery forming part of a low voltage power system to provide power to one or more low voltage loads forming part of the low voltage power system during the automatic engine stop irrespective of a state of charge of a high voltage battery forming part of a high voltage power system.

### Claim 2 (depends on 1)

A method as claimed in claim 1 wherein the method further comprises, if a state of charge of the low voltage battery drops to a predefined minimum allowable limit while the engine remains stopped, connecting the high voltage power system to the low voltage power system via a DC to DC converter and using the high voltage battery to power the low voltage loads.

### Claim 3 (depends on 1)

A method as claimed in claim 1 wherein the method further comprises, if a state of charge of the low voltage battery drops to a predefined minimum allowable limit while the engine remains stopped and the state of charge of the high voltage battery is below a predefined limit, connecting the high voltage power system to the low voltage power system via a DC to DC converter, restarting the engine and using a high voltage integrated electrical starter-generator driven by the engine forming part of the high voltage power system to power the low voltage loads.

### Claim 4 (depends on 1)

A method as claimed in claim 1 wherein the method further comprises disabling a DC to DC converter during the automatic engine stop so as to isolate the high voltage battery from the low voltage power system.

### Claim 5 (depends on 1)

A method as claimed in claim 1 wherein the method further comprises using a DC to DC converter to transfer energy from the high voltage battery to the low voltage battery after termination of the automatic engine stop to recharge the low voltage battery.

### Claim 6 (depends on 1)

A method as claimed in claim 1 wherein the high voltage system further comprises a belt driven integrated starter-generator driveably connected to the engine and the method further comprises using the belt driven integrated starter-generator as a motor to assist the engine to reduce fuel consumption of the engine.

### Claim 7 (depends on 1)

A method as claimed in claim 1 wherein the high voltage system further comprises a belt driven integrated starter-generator driveably connected to the engine and the method further comprises using the belt driven integrated starter-generator as a high voltage electrical generator to recharge the high voltage battery when energy can be recuperated from the engine with no fuel penalty.

### Claim 8

A mild hybrid electric vehicle having an engine driveably connected to an integrated starter-generator forming part of a high voltage power system that also includes a high voltage battery, a low voltage power system having a low voltage battery and at least one low voltage load, a DC to DC converter to selectively connect the high and low voltage systems together and an electronic controller to control operation of the engine, the high and low voltage power systems and the DC to DC converter wherein the electronic controller is operable to isolate the high voltage power system from the low voltage power system when the engine is automatically stopped in order to save fuel and use the low voltage battery to power the at least one low voltage load irrespective of a state of charge of the high voltage battery.

### Claim 9 (depends on 8)

A vehicle as claimed in claim 8 wherein the electronic controller is further operable to use the DC to DC converter to connect the high voltage system to the low voltage system and use the high voltage battery to recharge the low voltage battery when the engine is restarted after termination of an automatic engine stop.

### Claim 10 (depends on 8)

A vehicle as claimed in claim 8 wherein the electronic controller is operable to use the integrated starter generator as a motor to assist the engine to reduce fuel consumption of the engine.

### Claim 11 (depends on 8)

A vehicle as claimed in claim 8 wherein the electronic controller is operable to use the integrated starter generator as a generator to recharge the high voltage battery when energy can be recuperated from the engine with no fuel penalty.

### Claim 12 (depends on 8)

A vehicle as claimed in claim 8 wherein the electronic controller is operable to connect the high voltage power system to the low voltage power system via the DC to DC converter and use the high voltage battery to power the loads if a state of charge of the low voltage battery drops to a predefined minimum allowable limit while the engine remains stopped.

### Claim 13 (depends on 8)

A vehicle as claimed in claim 8 wherein the electronic controller is operable to connect the high voltage power system to the low voltage power system via the DC to DC converter, restart the engine and use the integrated starter-generator to power the low voltage loads if the state of charge of the low voltage battery drops to a predefined minimum allowable limit while the engine remains stopped and the state of charge of the high voltage battery is below a predefined limit.

### Claim 14

A vehicle comprising:
a traction battery;
an auxiliary battery;
a DC to DC converter configured to selectively electrically connect the traction and auxiliary batteries; and
a controller operable to, during an engine auto stop, isolate the traction battery from the auxiliary battery and use the auxiliary battery to power an auxiliary load irrespective of a state of charge of the traction battery.