Current limiting parallel battery charging system to enable plug-in or solar power to supplement regenerative braking in hybrid or electric vehicle
First Claim
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; and
a current limiting buffer connecting the first battery in parallel with second battery, the current limiting buffer comprising;
a connecting transistor having a current path connecting the first battery in parallel with the second battery and having a control terminal; and
a control circuit connected between the first battery and the second battery, and to the control terminal of the connecting transistor, the control circuit for determining a voltage difference between the first and the second batteries, and applying a voltage to the control terminal to control the amount of current flow between the first battery and the second battery.
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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 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 limiter 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 limiter 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).
43 Citations
14 Claims
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1. A battery charging system for a vehicle comprising:
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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 current limiting buffer connecting the first battery in parallel with second battery, the current limiting buffer comprising; a connecting transistor having a current path connecting the first battery in parallel with the second battery and having a control terminal; and a control circuit connected between the first battery and the second battery, and to the control terminal of the connecting transistor, the control circuit for determining a voltage difference between the first and the second batteries, and applying a voltage to the control terminal to control the amount of current flow between the first battery and the second battery. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for charging a battery charging for a vehicle comprising:
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providing an electric motor configured to draw current to operate as a drive motor for a vehicle and to supply current for regenerative braking; providing a first battery connected to the electric motor; providing a second battery; providing a battery charger connected to the second battery; and providing a transistor with a current path connecting the first battery in parallel with the second battery, the transistor having a current control terminal; and controlling voltage on the control terminal of the transistor to limit the amount of current flow between the first battery and the second battery. - View Dependent Claims (12, 13, 14)
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Specification