CURRENT CLAMPING PARALLEL BATTERY CHARGING SYSTEM TO SUPPLEMENT REGENERATIVE BRAKING IN ELECTRIC VEHICLE

• US 20110089904A1
• Filed: 12/22/2010
• Published: 04/21/2011
• Est. Priority Date: 12/04/2008
• Status: Abandoned Application

• Current Assignee: Thomas Allan Ward
• Original Assignee: Thomas Allan Ward
• Inventors: Ward, Thomas Allan
• Application Number:
  US12/976,269
• Publication Number:
  US 20110089904A1
• Time in Patent Office: Days
• US Class Current: 320/126
• CPC Class Codes: B60L 53/00 Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles
• CPC Class Codes: B60L 58/21 having the same nominal voltage
• CPC Class Codes: B60L 8/003 Converting light into electric energy, e.g. by using photo-voltaic systems
• CPC Class Codes: H02J 2310/48 for electric vehicles [EV] or hybrid vehicles [HEV]
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00304 Overcurrent protection
• CPC Class Codes: H02J 7/00309 Overheat or overtemperature protection
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters
• CPC Class Codes: H02J 7/35 with light sensitive cells
• 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 90/14 Plug-in electric vehicles

Abstract

To provide additional charge storage for an electric vehicle, an additional battery (100) is connected in parallel with a regenerative braking direct charged battery (22) through a current limiting or clamping circuit (104 or 120). The additional battery (100) is charged by an external charger such as a plug-in charger or a solar panel that supply minimal current to prevent generation of battery heat. Current flows from the additional battery (100) to the regenerative braking charged batteries (22) so that both batteries can be charged. However, when excessive charge is drawn to drive the vehicle electric motor (20), the current limiting or clamping circuit (104 or 120) serves to prevent the discharge of additional battery (100) from creating excessive heat in the additional battery (100). Further, when regenerative braking is applied the current clamping circuit (120), or a diode buffer (102) in combination with current limiter (104), serves to prevent charging from creating excessive heat in the additional battery (100) and eliminates the need for a cooling structure in the additional battery (100).

Claims

1. A battery charging system for a vehicle comprising:

electric motor configured to draw current to operate as a drive motor for a vehicle and to supply current for regenerative braking;

a first battery connected to the electric motor;

a second battery;

a battery charger connected to the second battery;

a diode buffer connected between the first battery and the second battery to substantially prevent current flow from the first battery toward the second battery; and

a current clamping circuit connecting the first battery to the second battery, the current clamping circuit limiting current flow to a maximum value from the second battery toward the first battery.

7. The battery charging system of claim 1, wherein the bi-directional current clamping circuit comprises:

a first connecting transistor having a current path connecting the first battery in parallel with the second battery and having a control terminal;

a second connecting transistor having a current path and a control terminal, and

a sensing resistor having a first terminal connected by a current path of the first connecting transistor to the first battery and having a second terminal connected by a current path of the second connecting transistor to the second battery;

a first control transistor having a current path connected from the second terminal of the sensing resistor to the control terminal of the first connecting transistor, and having a control terminal connected to the first terminal of the sensing resistor; and

a second control transistor having a current path connected from the first terminal of the sensing resistor to the control terminal of the second connecting transistor, and having a control terminal connected to the second terminal of the sensing resistor.

8. The battery charging system of claim 7, wherein the first and second connecting transistors and the first and second control transistors each comprise at least one of a BJT transistor and a CMOS transistor.

9. The battery charging system of claim 1, wherein the bi-directional current clamping circuit comprises:

a first connecting transistor having a current path connecting the first battery in parallel with the second battery and having a control terminal;

a second connecting transistor having a current path and a control terminal;

a sensing resistor having a first terminal connected by a current path of the first connecting transistor to the first battery and having a second terminal connected by a current path of the second connecting transistor to the second battery; and

a differential amplifier having a first input connected to the first terminal of the sensing resistor, a second input connected to the second terminal of the sensing resistor, a first output connected to the control terminal of the first connecting transistor and a second output complementary to the first output connected to the control terminal of the second connecting transistor.

2. A battery charging system for a vehicle comprising:

electric motor configured to draw current to operate as a drive motor for a vehicle and to supply current for regenerative braking;

a first battery connected to the electric motor;

a second battery;

a battery charger connected to the second battery; and

a bi-directional current clamping circuit connecting the first battery to the second battery, the bi-directional current clamping circuit limiting current flow to a maximum value both from the second battery toward the first battery and from the first battery toward the second battery.

3. The battery charging system of claim 2, wherein the bi-directional current clamping circuit comprises:

a connecting transistor having a current path connecting the first battery in parallel with the second battery and having a control terminal; and

a sensing resistor having a first terminal connected to the first battery and having a second terminal connected by a current path of the connecting transistor to the second battery;

a control transistor having a current path connected from the second terminal of the sensing resistor to the control terminal of the connecting transistor, and having a control terminal connected to the first terminal of the sensing resistor.

4. The battery charging system of claim 3,

wherein the connecting transistor comprises a CMOS transistor having a source-drain path forming the current path, and a gate forming the control terminal, and

wherein the control transistor comprises a CMOS transistor having a source-drain path forming the current path, and a gate forming the control terminal

5. The battery charging system of claim 3,

wherein the connecting transistor comprises a BJT transistor having a collector-emitter path forming the current path, and a base forming the control terminal, and

wherein the control transistor comprises a BJT transistor having a collector-emitter path forming the current path, and a base forming the control terminal

6. The battery charging system of claim 2, wherein the bi-directional current clamping circuit comprises:

a connecting transistor having a current path connecting the first battery in parallel with the second battery and having a control terminal; and

a sensing resistor having a first terminal connected to the first battery and having a second terminal connected by a current path of the connecting transistor to the second battery; and

a differential amplifier having a first input connected to the first terminal of the sensing resistor, a second input connected to the second terminal of the sensing resistor, and an output connected to the control terminal of the connecting transistor.