VOLTAGE DIVIDING VEHICLE HEATER SYSTEM AND METHOD

• US 20090021221A1
• Filed: 06/23/2008
• Published: 01/22/2009
• Est. Priority Date: 07/18/2007
• Status: Active Grant

• Current Assignee: Tesla Inc.
• Original Assignee: Tesla Motors Incorporated (Tesla Inc.)
• Inventors: Krauer, Jean-Pierre, Straubel, Jeffrey Brian, Hebert, Arthur Joseph, Nergaard, Troy Adam, Craven, Ian
• Granted Patent: US 8,049,460 B2
• Time in Patent Office: Days
• US Class Current: 320/153
• CPC Class Codes: B60L 1/08 Methods and devices for control or regulation
• CPC Class Codes: B60L 2200/26 Rail vehicles
• CPC Class Codes: B60L 2240/545 Temperature
• CPC Class Codes: B60L 2240/549 Current
• CPC Class Codes: B60L 2240/662 Temperature
• CPC Class Codes: B60L 2240/80 Time limits
• CPC Class Codes: B60L 50/64 Constructional details of batteries specially adapted for electric vehicles
• CPC Class Codes: B60L 53/14 Conductive energy transfer
• CPC Class Codes: B60L 58/21 having the same nominal voltage
• CPC Class Codes: B60L 58/27 by heating
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility
• CPC Class Codes: Y02T 90/14 Plug-in electric vehicles
• CPC Class Codes: Y02T 90/16 Information or communication technologies improving the operation of electric vehicles

Abstract

An apparatus comprising battery pack installed in an electric vehicle, a power supply coupled to the rechargeable battery pack, the power supply operable to provide a charge voltage to perform charging operations on the rechargeable battery pack;, a heater to heat a fluid to be circulated through the rechargeable battery pack, the fluid thermally coupled to a plurality of battery cells within the rechargeable battery pack, a switching circuit, the switching circuit coupled to the heater and to the power supply, the switching circuit operable in a first mode to couple the source of electrical power to the heater without coupling the source of electrical power to the rechargeable battery pack, the switching circuit operable in a second mode to couple a source of electrical power external to the electric vehicle to the power supply to form a recharging circuit in order to perform charging operations on the rechargeable battery pack.

Claims

1. An apparatus comprising:

a rechargeable battery pack installed in an electric vehicle;

a power supply coupled to the rechargeable battery pack, the power supply operable to provide a charge voltage to perform charging operations on the rechargeable battery pack;

a heater to heat a fluid to be circulated through the rechargeable battery pack, the fluid thermally coupled to a plurality of battery cells within the rechargeable battery pack;

a switching circuit, the switching circuit coupled to the heater and to the power supply,

the switching circuit operable in a first mode to couple the source of electrical power to the heater without coupling the source of electrical power to the rechargeable battery pack,

the switching circuit operable in a second mode to couple a source of electrical power external to the electric vehicle to the power supply to form a recharging circuit in order to perform charging operations on the rechargeable battery pack, wherein the switching circuit is operable to couple the heater in the recharging circuit during at least some portion of the recharging operations, or to perform the charging operation in the first mode without coupling the heater in the recharging circuit during any portion of the recharging operations.

2. The apparatus of claim 1, wherein in the second mode and if the heater is coupled in the recharging circuit during at least some portion of the charging operation, the switching circuit is operable to bypass the heater during another portion of the charging operation.

3. The apparatus of claim 1, including:

a charging control circuit coupled to the switching circuit, the charging control circuit operable to configure one or more switches within the switching circuit in order to provide either the first mode or the second mode.

4. The apparatus of claim 1, wherein in the second mode the switching circuit is operable to connect the heater in the recharging circuit by connecting the heater in series with one connection to the switching circuit, the one connection to the switching circuit connected to one input connection to the power supply.

5. The apparatus of claim 1, wherein in the second mode the switching circuit is operable to connect the heater in the recharging circuit by connecting the heater in series with one output connection of the power supply and with one terminal of the rechargeable battery pack.

6. The apparatus of claim 1, wherein in the first mode the switching circuit is operable to connect the heater directly across the source of electrical power as the source of electrical power is provided at a set of input connections to the switching circuit and without connecting the source of electrical power to a set of input terminals of the power supply.

7. The apparatus of claim 1, wherein in a third mode the switching circuit is operable to disconnect the heater from the source of electrical power and from the power supply, and to connect the heater directly across the terminals of the rechargeable battery pack in order to power the heater using electrical power provided by the rechargeable battery pack.

8. The apparatus of claim 1, wherein the source of electrical power includes an alternating current (AC) voltage source provided at the set of input connections to the switching circuit.

9. The apparatus of claim 1, further including:

a comparator circuit to compare a battery voltage of the rechargeable battery pack to a source of electrical power coupled to input connections of the power supply, the comparator circuit operable to compare a battery voltage of the rechargeable battery pack to a voltage of the source of electrical power, and to provide an output signal when the battery voltage is less than a line voltage offset value, the line voltage offset value calculated based on a value added to a determined voltage level for the line source voltage; and

the charging control circuit coupled to receive the output signal of the comparator, the charging control circuit operable include or to not include the heater in the recharging circuit during a charging operation based on the output signal from the comparator.

10. The apparatus of claim 9, wherein the comparator includes a microcontroller, and wherein the value added is stored in software accessible by the microcontroller.

11. The apparatus of claim 9, wherein the comparator includes a digital signal processor.

12. The apparatus of claim 1, wherein the battery cells are a plurality of 18650 form-factor lithium-ion cell.

13. A method comprising:

determining in a first mode that a rechargeable battery pack in an electric vehicle needs to be heated, and coupling electrical power from a source external to the electric vehicle across a heater that is thermally coupled to the rechargeable battery pack;

determining in a second mode that a charge operation on a rechargeable battery pack is to be performed by comparing a supply voltage to a battery voltage of the rechargeable battery pack to determine a line voltage offset value;

generating in the second mode a charging voltage from the supply voltage; and

initiating in the second mode a charging operation of the rechargeable battery pack by coupling the charging voltage to the rechargeable battery pack, wherein coupling the charging voltage to the rechargeable battery pack includes coupling the heating element in series between the supply voltage and a set of power inputs to a power supply providing the charge voltage to the rechargeable battery pack when the battery voltage is less than a line voltage offset value, and bypassing the heating element when the battery voltage is not less than the line voltage offset value.

14. The method of claim 13, wherein coupling power from a source external to the electric vehicle across the heater includes providing an alternating current power source to a set of inputs of a switching circuit, and configuring the switching circuit to couple the alternating current power source across the heater without coupling the alternating current power source to a set of inputs to a power supply coupled to the rechargeable battery pack.

15. The method of claim 13, including determining in a third mode that the rechargeable battery pack needs to be heated, and coupling power from the rechargeable battery pack across the heating element to heat the rechargeable battery pack.

16. The method of claim 15, wherein coupling power from the rechargeable battery pack across the heater includes coupling the heating element across a set of terminals of the rechargeable battery pack.

17. The method of claim 16, wherein coupling power from the rechargeable battery pack across the heating element includes configuring the switches in the switching circuit to disconnect a power supply used to recharge the rechargeable battery pack from the terminals of the rechargeable battery pack.

18. The method of claim 13, further including:

circulating the fluid through the rechargeable battery pack during the charging while the heating element is coupled between the supply voltage and the set of power inputs to the power supply.

19. The method of claim 18, further including:

monitoring a temperature of rechargeable battery pack; and

cooling the fluid circuited through the recharge battery pack when the monitored temperature exceeds a predetermined temperature level.

20. The method of claim 13, further including:

comparing the supply voltage to the battery voltage while charging the rechargeable battery pack and having the heating element between the supply voltage and a set of power inputs to a power supply to determine if the battery voltage exceeds a bypass threshold value, wherein the bypass threshold level is calculated based on the line voltage offset value; and

bypassing the heating element and continuing the charging when the battery voltage exceeds a bypass threshold value.

21. The method of claim 13, wherein determining that a charge operation on a rechargeable battery pack is to be performed includes determining that the rechargeable battery pack is to be charged to one of a plurality of predetermined battery charge levels.

22. The method of claim 13, further including:

controlling a current provided during the charging operation, both when the heating element is coupled between the supply voltage and a set of power inputs and when the heating element is bypassed.

23. The method of claim 13, wherein generating a charging voltage from the supply voltage includes the supply voltage being an alternating current power source having a sinusoidal voltage waveform.

24. A system comprising:

a vehicle including a rechargeable battery pack, the rechargeable battery pack to provide at least a portion of the power used to propel the vehicle;

a heating element to heat a fluid to be circulated through the rechargeable battery pack, the fluid thermally coupled to battery cells within the rechargeable battery pack;

a charger operable to couple to a line source of electrical power and to be detachably coupled to the vehicle, the charger to provide electrical power from the line source for performing charging operations of the rechargeable battery pack;

a comparator circuit to compare a battery voltage of the rechargeable battery pack to a line source voltage coupled to inputs of the power supply, the comparator circuit operable to compare the battery voltage to the line source voltage and to provide an output signal when the battery voltage is less than a line voltage offset value, the line voltage offset value calculated based on a value added to a determined voltage level for the line source voltage; and

a control circuit coupled to receive the output signal of the comparator, and when a charge operation of the rechargeable battery pack is to be initiated, the control circuit operable to couple the line source voltage to the power supply, wherein the control circuit is to couple the heating element in series between the line source voltage and the power supply when the comparator circuit is providing the output signal indicating that the battery voltage is less than the line voltage offset value, and to bypass the heating element if the comparator is not providing the output signal indicating that the battery voltage is less than the line voltage offset value.

25. The system of claim 24, wherein the comparator circuit is operable to monitor the battery voltage while the rechargeable battery pack is coupled to the heating element and the voltage source during a recharging operation, and to provide a bypass signal when the battery voltage exceeds a bypass threshold value, wherein the bypass threshold level is calculated based on the line voltage offset value;

and

wherein the control circuit is coupled to receive the bypass signal and to bypass the heating element and continue the charging operation.

26. The system of claim 24, wherein the control circuit is operable to charge the rechargeable battery pack to one of a plurality of predetermined battery charge levels.

27. The system of claim 24, wherein the heating element, when coupled between the voltage source and the rechargeable battery pack, is coupled in series with the rechargeable battery pack to form a voltage divider for a voltage provided from the voltage source.