# US 2017/0282902 A1 · System and method for coordinated operation of integrated starter generator and power converter in a vehicle

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- Number: US 2017/0282902 A1
- Document ID: US20170282902A1
- Status: Published application
- Kind: A1
- Application number: 15/085,037
- Filed: 2016-03-30
- Published: 2017-10-05
- Earliest claimed: 2016-03-30
- Assignees: Ford Global Technologies, LLC
- Applicants: Ford Global Technologies, LLC
- Inventors: Marvin Paul KRASKA; Mark Steven YAMAZAKI; Mark J. FERREL
- Web page: https://patentgrep.com/patent/US20170282902A1

## CPC

- 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)}
- B60L 50/16: with provision for separate direct mechanical propulsion
- B60L 58/12: responding to state of charge [SoC]
- B60L 58/20: having different nominal voltages
- B60W 10/06: including control of combustion engines
- B60W 10/08: including control of electric propulsion units, e.g. motors or generators
- B60L 2210/12: Buck converters
- B60L 2210/14: Boost converters
- B60L 2240/427: Voltage
- B60L 2240/429: Current
- B60L 2240/441: Speed
- B60L 2240/527: Voltage
- B60L 2240/529: Current
- B60L 2240/80: Time limits
- B60W 2710/087: Power change rate
- 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
- 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
- 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 vehicle includes a hybrid powertrain with a motor/generator electrically coupled to a high-voltage bus to provide propulsion. The vehicle also includes an integrated starter/generator electrically copulated to a low-voltage bus and configured to start the engine. A vehicle power system includes a power converter electrically coupled between the high-voltage bus and the low-voltage bus. During engine start events, operation of the integrated starter/generator is coordinated with operation of the power converter to reduce voltage sag on the low-voltage bus. An increase rate of current supplied to the integrated starter/generator is limited such that a current output of the power converter does not saturate at a maximum current output for a period of time after initiating the engine start event.

## Claims

### Claim 1

A vehicle comprising:
an electric machine electrically coupled to a low-voltage bus and coupled to an engine;
a power converter electrically coupled between a high-voltage bus and the low-voltage bus; and
a controller programmed to, in response to an increase in current demand for the electric machine, limit a current increase rate of the electric machine to a rate that prevents saturation of a power converter current output for at least a predetermined time.

### Claim 2 (depends on 1)

The vehicle of claim 1 wherein the controller is further programmed to receive a remaining current capacity from the power converter, and wherein the rate is based on the remaining current capacity and the predetermined time.

### Claim 3 (depends on 1)

The vehicle of claim 1 wherein the controller is further programmed to, in response to a remaining current capacity of the power converter being less than a predetermined amount, limit the current increase rate to a predetermined minimum rate.

### Claim 4 (depends on 1)

The vehicle of claim 1 wherein the controller is further programmed to, in response to the power converter current output exceeding a predetermined current indicative of the power converter current output being saturated, limit the current increase rate to a predetermined rate.

### Claim 5 (depends on 1)

The vehicle of claim 1 wherein the controller is further programmed to, in response to the engine remaining in a non-running condition after a predetermined engine cranking time has expired, cease limiting the current increase rate.

### Claim 6 (depends on 1)

The vehicle of claim 1 wherein the predetermined time increases as a state of charge of a low voltage battery decreases.

### Claim 7

A vehicle power system comprising:
a power converter electrically coupled between a high-voltage bus and a low-voltage bus; and
a controller programmed to, in response to an increase in current demand of an electric machine for engine cranking powered from the low-voltage bus exceeding a predetermined amount, limit a current increase rate of the electric machine to a predetermined rate to limit a power converter output current increase rate.

### Claim 8 (depends on 7)

The vehicle power system of claim 7 wherein the controller is further programmed to receive a signal indicative of a remaining current capacity of the power converter and the predetermined amount is the remaining current capacity.

### Claim 9 (depends on 7)

The vehicle power system of claim 7 wherein the controller is further programmed to receive a signal indicative of a remaining current capacity of the power converter and the predetermined rate is based on the signal.

### Claim 10 (depends on 7)

The vehicle power system of claim 7 wherein the predetermined rate is based on a rate of current increase for the electric machine to increase an engine speed to a predetermined speed within a predetermined time.

### Claim 11 (depends on 7)

The vehicle power system of claim 7 wherein the predetermined rate is based on a predetermined duration for engine cranking.

### Claim 12 (depends on 7)

The vehicle power system of claim 7 wherein the controller is further programmed to, in response to signals indicative of an engine not running after a predetermined duration, cease limiting the current increase rate.

### Claim 13 (depends on 7)

The vehicle power system of claim 7 wherein the controller is further programmed to, in response to current output of the power converter being saturated at a rated current output, limit the current increase rate of the electric machine to a second predetermined rate.

### Claim 14

A method comprising:
limiting by a controller a rate of current increase of an integrated starter generator coupled to a low-voltage bus to a rate that is less than a demanded increase rate such that saturation of a current output of a power converter coupled to the low-voltage bus is prevented for at least a predetermined time.

### Claim 15 (depends on 14)

The method of claim 14 further comprising receiving by the controller a signal indicative of a remaining current capacity from the power converter.

### Claim 16 (depends on 15)

The method of claim 15 wherein the rate is based on the signal indicative of the remaining current capacity.

### Claim 17 (depends on 14)

The method of claim 14 further comprising limiting by the controller the rate of current increase to a predetermined minimum rate in response to the current output becoming saturated.

### Claim 18 (depends on 14)

The method of claim 14 further comprising increasing by the controller a current to the integrated starter generator at the demanded increase rate in response to receiving signals indicative of an engine not running after a predetermined duration.

### Claim 19 (depends on 14)

The method of claim 14 further comprising outputting by the controller a signal indicative of the rate of current increase to the power converter.

### Claim 20 (depends on 19)

The method of claim 19 further comprising receiving by the power converter the signal and controlling the current output according to the signal.