WO2009067810A1

WO2009067810A1 - Apparatus, method and memory for improving the performance and charging of hybrid electric vehicles

Info

Publication number: WO2009067810A1
Application number: PCT/CA2008/002093
Authority: WO
Inventors: Neil S. Simmonds; Piotr Drozdz; Lorne Gettel
Original assignee: Advanced Lithium Power Inc.
Priority date: 2007-11-30
Filing date: 2008-12-01
Publication date: 2009-06-04

Abstract

Disclosed herein are a method, apparatus and memory for charging or discharging a powertrain battery of a hybrid electric or plug-in hybrid electric vehicle. The method includes obtaining driving conditions along a route to be travelled by the vehicle; projecting a driving period during which the vehicle will be subject to the driving conditions; determining whether the powertrain battery will fully discharge during the driving period; and charging the powertrain battery, prior to the driving period, when it is determined that the powertrain battery will fully discharge during the driving period. Alternatively, the method includes obtaining a current cost of electricity; and charging the powertrain battery when the current cost of electricity is below a certain threshold.

Description

APPARATUS, METHOD AND MEMORY FOR IMPROVING THE PERFORMANCE AND CHARGING OF HYBRID ELECTRIC VEHICLES

Field of the Invention

The present invention relates to an apparatus, method and memory for improving at least one of the performance and charging of hybrid electric vehicles ("HEVs") and plug-in hybrid electric vehicles ("PHEVs").

Background of the Invention

In recent years, the use of wireless communication systems in automobiles has become more popular. Such systems can be used, for example, to track automobiles using the Global Positioning System ("GPS") and to provide feedback in the form of real-time traffic and other road conditions; to distribute real-time television and other data services to automobile passengers; to collect from and transmit to automobiles road safety information; and to control automobile security systems remotely. An example of one such system is disclosed in US 2007/0239354 to Kwon. Another example of such a system is disclosed in US 2007/0233342 to DiCroce et al.

None of the above-mentioned prior art, however, uses wireless communications to address concerns that are specific to HEVs and PHEVs.

Accordingly, there is a need for a wireless communication system designed to address concerns specific to one or both of HEVs and PHEVs.

Summary of the Invention

According to a first aspect of the invention, there is provided a method for charging or discharging a powertrain battery of a hybrid electric or plug-in hybrid electric vehicle. The method includes obtaining driving conditions along a route to be travelled by the vehicle; projecting a driving period during which the vehicle will be subject to the driving conditions; determining whether the powertrain battery will fully discharge during the driving period; and charging the powertrain battery, prior to the driving period, when it is determined that the powertrain battery will fully discharge during the driving period.

The method may further include determining whether the powertrain battery will fully charge during the driving period; and discharging the powertrain battery, prior to the driving period, when it is determined that the powertrain battery will fully charge during the driving period.

The powertrain battery may be charged such that it will not fully discharge during the driving period. Analogously, the powertrain battery may be discharged such that it will not fully charge during the driving period.

Determining whether the powertrain battery will fully discharge during the driving period may include determining whether expected torque and rotations-per- minute of an electric motor of the vehicle will increase and decrease, respectively, past pre-set discharge thresholds during the driving period, and wherein determining whether the powertrain battery will fully charge during the driving period comprises determining whether expected torque and rotations-per- minute of an electric motor of the vehicle will decrease and increase, respectively, past pre-set charge thresholds during the driving period.

Obtaining driving conditions along a route to be travelled by the vehicle may include accessing a map database to obtain a map that includes a destination of the vehicle; accessing a global positioning satellite system to determine a current position of the vehicle; and obtaining the driving conditions for a portion of the route between the current position and destination of the vehicle.

The driving conditions may be obtained wirelessly and include information on traffic conditions and topographical information.

According to a further aspect of the invention, there is provided a memory having encoded thereon steps and instructions for execution by a controller to carry out the above method. According to a still further aspect of the invention, there is provided an apparatus for charging or discharging a powertrain battery of a hybrid electric or plug-in hybrid electric vehicle. The apparatus may include a controller; a memory, in communication with the controller, having encoded thereon steps and instructions for execution by the controller the above method; and a charger/discharger, in communication with the controller, for charging and discharging the powertrain battery.

The apparatus may further include a map database, in communication with the controller, for storing a map; an input unit, in communication with the controller, for obtaining information concerning a destination of the vehicle from a user; and a display unit, in communication with the controller, for displaying the map to the user; a global positioning satellite system receiver, in communication with the controller, for obtaining a current position of the vehicle; or a cellular transceiver, in communication with the controller, for wirelessly obtaining driving conditions.

According to a still further aspect of the invention, there is provided a method for charging a powertrain battery of a plug-in hybrid electric vehicle. The method may include obtaining a current cost of electricity; and charging the powertrain battery when the current cost of electricity is below a certain threshold. The method may further include ceasing charging the powertrain battery when the current cost of electricity is above the certain threshold. The current cost of electricity may be obtained wirelessly.

According to another aspect of the invention, there is provided a memory having encoded thereon steps and instructions for execution by a controller to carry out the above method for charging a powertrain battery of a plug-in hybrid electric vehicle.

According to another aspect of the invention, there is provided an apparatus for charging a powertrain battery of a plug-in hybrid electric vehicle. The apparatus includes a controller; a memory, in communication with the controller, having encoded thereon steps and instructions for execution by the controller the method for charging a powertrain battery of a plug-in hybrid electric vehicle; and a charger, in communication with the controller, for charging the powertrain battery. The apparatus may also include a cellular transceiver, in communication with the controller, for obtaining the current cost of electricity.

Brief Description of the Drawings

Figure 1 depicts an automobile in communication with a base station according to a first embodiment of the present invention;

Figure 2 is a schematic illustrating a controller in communication with various components according to the first embodiment;

Figure 3 is a flowchart depicting an algorithm for improving the performance of a powertrain of an HEV/PHEV according to the first embodiment; and

Figure 4 is a flowchart depicting the determination of a relatively inexpensive time during which to recharge a powertrain battery of a PHEV, according to a second embodiment of the present invention.

Detailed Description of an Exemplary Embodiment of the Invention

Both HEVs and PHEVs utilize an internal combustion engine in conjunction with an electric motor/generator. Generally, internal combustion engines are more efficient than electric motors/generators during periods of low-torque, high-RPM vehicle operation; similarly, electric motors/generators are more efficient than internal combustion engines during periods of high-torque, low-RPM vehicle operation. Consequently, one concern faced by a driver of an HEV/PHEV that is not faced by a driver of a traditional automobile is how to efficiently use both the internal combustion engine and electric motor/generator when the HEV/PHEV is to be driven along a roadway that will result in both low-torque, high-RPM and high-torque, low-RPM driving conditions. It would be advantageous to know when long periods of high-torque, low-RPM driving are forthcoming so as to be able to charge the battery in preparation for use during these periods. Furthermore, and related specifically to PHEVs, it can be relatively expensive to charge a PHEV when general demand for electricity is high, as the cost of electricity can vary directly with demand. Consequently, one concern faced by a driver of a PHEV is how to determine when the PHEV can be inexpensively charged. It would also be advantageous to know when, during a day, demand for and therefore the cost of power is relatively low, so as to be able to recharge the battery during such periods.

The embodiments discussed below address these concerns.

Referring now to Figures 1 and 2, there is shown an apparatus 10 for improving the performance of an HEV/PHEV 12. The powertrain of the HEV/PHEV 12 includes an electric motor/generator, a motor controller/inverter, an internal combustion engine or a fuel cell, and a battery. This battery, which provides energy to the electric motor for moving the HEV/PHEV 12 and which is charged using methods such as, for example, regenerative braking, is hereinafter referred to as the "powertrain battery". Exemplary types of batteries that can be used include Nickel Metal Hydride and Lithium Ion batteries. In the embodiment depicted in Figure 1 , the HEV/PHEV 12 has installed therein a controller or processor 20 that controls various elements of the apparatus 10. The elements of the apparatus 10 include a GPS receiver 22 for communication with a GPS satellite A; a memory or other computer readable medium having stored thereon a map database 28 for displaying maps overlaid with location information obtained via the GPS receiver 22; an input unit 24 for accepting a driver's input related to, for example, destination; a display unit, which can, for example, graphically indicate a driver's position on a map; memory 26, for storing instructions and data for execution and use, respectively, by the controller 20; a wireless transceiver 32, capable of communicating with a base station B such that the apparatus 10 can access the Internet; and a charger/discharger 34, for charging and discharging the powertrain battery of the HEV/PHEV 12. The charger/discharger 34 may be, for example, a vehicle engine control unit. Referring now to Figures 3 and 4, there are depicted algorithms stored in the memory 26 that are implemented by the controller 20. Figure 3 depicts an algorithm used to increase the efficiency of a powertrain of the HEV/PHEV 12 during driving. Typically, the efficiency of the electric motor/generator is greater than that of an internal combustion engine during high-torque and low-RPM periods. Periods of high-torque and low-RPM often encountered by drivers include those periods during which the HEV/PHEV 12 is in heavy traffic or engaged in relatively steep ascents. In contrast, during periods of low-torque and high-velocity, the HEV/PHEV 12 is ideally charging the powertrain battery using a method such as regenerative braking. During prolonged periods that are conducive to either powertrain battery charging or use, the powertrain battery may become fully charged or fully depleted, respectively, notwithstanding that the period of high-torque/low-RPM or low-torque/high velocity may be continuing. If this occurs, the powertrain battery is not being used as efficiently as it could be.

Accordingly, the algorithm depicted in Figure 3 seeks to pre-emptively charge or discharge the powertrain battery by using information about projected driving conditions gathered wirelessly from the Internet. At step 110, the driver first inputs a travel destination to which the driver wishes to drive in the HEV/PHEV 12. At step 140 the map database 28 is accessed to obtain a map that includes the start and destination locations, and a planned route is calculated and plotted on the map. At step 120, the apparatus 10 obtains the HEV/PHEV 12's position from the GPS satellite 16 via the GPS receiver 22 and then plots the position on the map. At step 130, driving conditions to which the HEV/PHEV 12 will be subject for a certain time ("driving period") and which are pertinent to determining whether the powertrain battery should be charged or discharged are obtained from the Internet via the cellular transceiver 32. In this exemplary embodiment, these conditions include topographical information and real-time traffic conditions along the planned route. Topographical information can be obtained, for example, from a service such as Google™ Earth. Such conditions affect the projected torque, RPM, and velocity of the HEV/PHEV 12. At step 150, the planned route and map are displayed on the display unit 30. At step 160, the controller 20 determines whether the projected driving conditions along the planned route are such that the expected torque and RPM are to increase and decrease, respectively, past pre-set discharge thresholds for a prolonged period of time (the "Discharge Period"). The Discharge Period can be equal to or less than the driving period. If the expected torque and RPM are such that the current powertrain battery charge is expected not to be sufficient to power the HEV/PHEV 12 during the Discharge Period, the powertrain battery is pre-emptively charged at step 190 and the controller 20 returns to step 120. If the controller 20 determines that the powertrain battery is not to be so charged, the controller 20 proceeds to step 170 and determines whether the expected torque and velocity are to decrease and increase, respectively, past pre-set charge thresholds for a prolonged period of time (the "Charge Period"). The Charge Period can be equal to or less than the driving period. If the expected torque and velocity are such that the current powertrain battery charge is so high that it will become fully charged during the Charge Period, the powertrain battery is pre-emptively discharged at step 200 (e.g. the electric motor/generator is used to accelerate the HEV/PHEV 12 when it otherwise wouldn't be so used) and the controller 20 then returns to step 120. If projected driving conditions do not dictate deviating from a standard charge/discharge algorithm (not shown), then the controller 20 merely loops back to step 120 via step 180 until the driver reaches the destination.

For example, presume that the planned route is such that the HEV/PHEV 12 is about to begin traveling steeply uphill for a Discharge Period of about 30 minutes. The Discharge Period can be calculated by, for example, presuming the current speed of the HEV/PHEV 12 is intended to be maintained over the portion of the driving period during which the powertrain battery will be discharged. The controller may access a look-up table in the memory 26 which states that given the topographical information and driving conditions obtained via the transceiver 32, the powertrain battery will be required to supply about 1.5 kW of power over 30 minutes to propel the HEV/PHEV 12 during the Discharge Period, or about 0.75 kWH of energy. If the powertrain battery is charged such that it is only able to supply about 0.5 kW of power over 30 minutes (0.25 kWH of energy), then the controller 20 instructs the charger/discharger 34 to charge the powertrain battery by an additional 0.50 kWH such that the powertrain battery will be able to power the HEV/PHEV 12 during the entirety of the Discharge Period.

While to "fully" discharge the powertrain battery can mean to discharge the powertrain battery to 0%, this is not the case for all embodiments. In certain embodiments, to "fully" discharge the powertrain battery can mean to discharge the powertrain battery as much as is chemically safe to do so, for example. In the case of a spinel or manganese dioxide based cell, a "fully discharged" cell may have a voltage reading of 2.5 Volts per cell; a "fully discharged" iron phosphate based cell may have a voltage reading of 2.0 Volts per cell.

Referring now to Figure 4, there is depicted an algorithm used to inexpensively charge the powertrain battery in the PHEV 12. The PHEV 12 is first plugged into an electrical outlet that is typically coupled to a local power grid. The cost of electricity varies with demand, with the cost higher at times of high, rather than low, demand. Following plugging in the PHEV 12, at step 330, the controller 20 determines whether the powertrain battery is charged. If so, no charging is required, and the controller 20 performs no further steps. If charging is required, the controller 20 obtains the current cost of electricity from the Internet via the cellular transceiver 32 at step 310. The cost of electricity can be obtained from the electricity provider, for example. If the cost of electricity is above a certain price (the "Charging Price"), as set by the driver, then the controller 20 does not charge the powertrain battery because the Charging Price is too high to justify charging the powertrain battery. It may be cheaper, for example, to operate the PHEV 12 using gasoline, or it may be expected that the price of electricity will decrease later on in the period during which the PHEV 12 is plugged in. If the cost of electricity is below the Charging Price, then the controller 20 charges the powertrain battery at step 330 and periodically checks the current price of electricity by looping back to step 300. If the price increases above the Charging Price, charging ceases until the price again decreases below the Charging Price, or until the PHEV 12 is unplugged. Examples of alternative embodiments of the algorithm depicted in Figure 4 include using interrupts, as opposed to polling, to alert the controller 20 to changes in electricity prices, and include variations in the algorithm used to determine whether to charge the powertrain battery or not (e.g.: also obtaining the current price of gas to determine the Charging Price). In this manner, the controller 20 can use information wirelessly obtained via the cellular transceiver 32 to initiate, cease, or re-initiate charging of the powertrain battery in an economical and efficient fashion. Another advantage to charging the powertrain battery during times of relatively low demand is that the load on the local power grid is better distributed over time, which can aid in the prevention of brownouts or blackouts.

The present invention has been described with regard to a plurality of illustrative embodiments. However, it will be apparent to persons skilled in the art that a number of variations and modifications can be made without departing from the scope of the invention as defined in the claims.

Claims

Claims:

1. A method for charging or discharging a powertrain battery of a hybrid electric or plug-in hybrid electric vehicle, the method comprising:

(a) obtaining driving conditions along a route to be travelled by the vehicle;

(b) projecting a driving period during which the vehicle will be subject to the driving conditions;

(c) determining whether the powertrain battery will fully discharge during the driving period; and

(d) charging the powertrain battery, prior to the driving period, when it is determined that the powertrain battery will fully discharge during the driving period.

2. A method as claimed in claim 1 further comprising:

(a) determining whether the powertrain battery will fully charge during the driving period;

(b) discharging the powertrain battery, prior to the driving period, when it is determined that the powertrain battery will fully charge during the driving period.

3. A method as claimed in claim 2 wherein the powertrain battery is charged such that it will not fully discharge during the driving period.

4. A method as claimed in claim 3 wherein the powertrain battery is discharged such that it will not fully charge during the driving period.

5. A method as claimed in claim 4 wherein determining whether the powertrain battery will fully discharge during the driving period comprises determining whether expected torque and rotations-per-minute of an electric motor of the vehicle will increase and decrease, respectively, past pre-set discharge thresholds during the driving period, and wherein determining whether the powertrain battery will fully charge during the driving period comprises determining whether expected torque and rotations-per-minute of an electric motor of the vehicle will decrease and increase, respectively, past pre-set charge thresholds during the driving period.

6. A method as claimed in claim 5 wherein obtaining driving conditions along a route to be travelled by the vehicle comprises:

(a) accessing a map database to obtain a map that includes a destination of the vehicle;

(b) accessing a global positioning satellite system to determine a current position of the vehicle; and

(c) obtaining the driving conditions for a portion of the route between the current position and destination of the vehicle.

7. A method as claimed in claim 6 wherein the driving conditions are obtained wirelessly and include information on traffic conditions and topographical information.

8. A memory having encoded thereon steps and instructions for execution by a controller to carry out the method of any one of claims 1 to 7.

9. An apparatus for charging or discharging a powertrain battery of a hybrid electric or plug-in hybrid electric vehicle, the apparatus comprising:

(a) a controller;

(b) a memory, in communication with the controller, having encoded thereon steps and instructions for execution by the controller the method of any one of claims 1 to 7; and (c) a charger/discharger, in communication with the controller, for charging and discharging the powertrain battery.

10. An apparatus as claimed in claim 9 further comprising a map database, in communication with the controller, for storing a map.

11. An apparatus as claimed in claim 10 further comprising an input unit, in communication with the controller, for obtaining information concerning a destination of the vehicle from a user; and a display unit, in communication with the controller, for displaying the map to the user.

12. An apparatus as claimed in claim 11 further comprising a global positioning satellite system receiver, in communication with the controller, for obtaining a current position of the vehicle.

13. An apparatus as claimed in claim 12 further comprising a cellular transceiver, in communication with the controller, for wirelessly obtaining driving conditions.

14. A method for charging a powertrain battery of a plug-in hybrid electric vehicle, the method comprising:

(a) obtaining a current cost of electricity; and

(b) charging the powertrain battery when the current cost of electricity is below a certain threshold.

15. A method as claimed in claim 14 further comprising ceasing charging the powertrain battery when the current cost of electricity is above the certain threshold.

16. A method as claimed in claim 15 wherein obtaining a current cost of electricity is performed wirelessly.

17. A memory having encoded thereon steps and instructions for execution by a controller to carry out the method of any one of claims 14 to 17.

18. An apparatus for charging a powertrain battery of a plug-in hybrid electric vehicle, the apparatus comprising:

(a) a controller;

(b) a memory, in communication with the controller, having encoded thereon steps and instructions for execution by the controller the method of any one of claims 14 to 17; and

(c) a charger, in communication with the controller, for charging the powertrain battery.

19. An apparatus as claimed in claim 18 further comprising a cellular transceiver, in communication with the controller, for obtaining the current cost of electricity.