# US 2010/0168946 A1 · Electric Vehicle Control

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- Number: US 2010/0168946 A1
- Document ID: US20100168946A1
- Status: Published application
- Kind: A1
- Application number: 12/651,292
- Filed: 2009-12-31
- Published: 2010-07-01
- Earliest claimed: 2008-12-31
- Inventors: Mark Snyder
- Web page: https://patentgrep.com/patent/US20100168946A1

## CPC

- H02P 6/182: using back-emf in windings
- B60L 15/2009: {for braking}
- B60L 2240/16: longitudinal
- B60L 2240/18: lateral
- B60W 2520/105: Longitudinal acceleration
- B60W 2520/125: Lateral acceleration
- F16H 59/48: Inputs being a function of acceleration
- F16H 59/66: Road conditions, e.g. slope, slippery
- F16H 61/0213: {characterised by the method for generating shift signals}
- F16H 2059/663: {Road slope}
- Y02T 10/64: Electric machine technologies in electromobility
- Y02T 10/72: Electric energy management in electromobility
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- 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
- 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
- F16H: GEARING
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

A method for controlling an electric vehicle includes computing an electric motor RPM based on a computed Back Electromotive Force (BEMF). Modern electric vehicle designs include intelligent control of the electric motors and transmissions to respond to operator controls and provide efficient operation to extend battery life. An accurate measure of motor RPM is required for such control. Various methods are available for obtaining motor RPM, but most require external sensors susceptible to damage from road debris and the like. The BEMF is proportional to motor speed and independent of motor load. The BEMF may further be computed from the difference between IR loss and motor voltage. The motor RPM is them computed from BEMF using data recorded for the individual motor.

## Claims

### Claim 1

A method for estimating electric motor RPM based on a computed Back Electromotive Force (BEMF) of the electric motor, the method comprising:
obtaining RPM verus the BEMF data for the electric motor comprising:
rotating the motor shaft of the electric motor over an RPM range covering the normal operating range of the electric motor;
measuring BEMF versus RPM over the RPM range; and
recording the BEMF versus RPM data for later real time use;
estimating a real time BEMF of the electric motor during the later use of the electric motor, comprising:
measuring a motor voltage at electric motor terminals;
measuring a motor current through the electric motor corresponding to the motor voltage measurement;
computing IR loss by multiplying the motor current times a dynamic internal resistance of the electric motor; and
computing the BEMF by subtracting the IR loss from the motor voltage;
estimating the electric motor RPM by comparing the real time BEMF to the recorded BEMF versus RPM data; and
providing the estimated RPM to an intelligent controller to optimally control the motor.

### Claim 2 (depends on 1)

The method of claim 1, further including providing the estimated RPM to an intelligent controller to optimally control a transmission.

### Claim 3

A method for obtaining an adjusted operator signal to an electronic controller to provide power and regenerative braking which mimic the position of a power control operator interface and a braking control operator interface, the method comprising:
measuring positions of a power actuator and/or a braking actuator;
converting the positions to a power signal and a braking signal;
processing the power signal and the braking signal to obtain adjusted power and braking signal to provide a desired acceleration or braking compensating for vehicle speed, transmission gearing, road incline, etc.; and
providing current to a motor based on the adjusted power and braking signal.

### Claim 4

A method for determining optimal shift points, the method comprising:
measuring X, Y, and Z accelerometers to obtain Xm, Ym, and Zm accelerometer measurements;
computing a vehicle incline from the Y and Z accelerometer measurements;
using the vehicle incline to correct the X accelerometer measurement for the vehicle incline to obtain actual fore-aft vehicle acceleration; and
determining whether or not to shift the transmission based on the incline and for-aft acceleration.