Power management for electric vehicles
An apparatus for managing power in an electric vehicle includes a control circuit and a first switch. The control circuit is configured to generate a first control signal based on a current of a battery operable for powering the electric vehicle, and to generate a second control signal based on a voltage of the battery. The first switch is configured to control connection of the battery to a power source and a load in the electric vehicle according to the first control signal. The first control signal controls a voltage at a terminal of the first switch to maintain the current of the battery to be substantially equal to a current setting, and the second control signal controls the battery to switch between a first state and a second state.
1. An apparatus for managing power in an electric vehicle, comprising;
a control circuit configured to generate a first control signal based on a current of a battery operable for powering said electric vehicle, and generate a second control signal based on a voltage of said battery; and
a first switch, coupled to said control circuit, configured to control connection of said battery to a power source and a load in said electric vehicle according to said first control signal,
wherein said first control signal controls a voltage at a terminal of said first switch to maintain said current of said battery to be substantially equal to a current setting, and wherein said second control signal controls said battery to switch between a first state and a second state.
2. The apparatus as claimed in claim 1 , wherein
said first switch comprises a transistor, and
a voltage at a gate of said transistor is controlled by said first control signal.
3. The apparatus as claimed in claim 1 , wherein if said current is greater than said current setting, said first control signal controls said voltage at said terminal of said first switch to adjust the conduction of said first switch.
4. The apparatus as claimed in claim 1 , wherein said first state is a charging state and said second state is a discharging state.
5. The apparatus as claimed in claim 4 , wherein
if said voltage of said battery is less than a start-up voltage threshold of said load, then said second control signal controls said battery to operate in said charging state, and
in said charging state, said power source provides said current to charge said battery via said first switch and provides power to said load.
6. The apparatus as claimed in claim 4 , wherein
if said voltage of said battery is greater than an output voltage of said power source, said second control signal controls said battery to operate in said discharging state, and
in said discharging state, a discharging current flows from said battery through said first switch to said load.
7. The apparatus as claimed in claim 1 , further comprising a second switch, coupled to said first switch and said control circuit, configured to control connection of said power source to said battery and said load based on said second control signal.
8. The apparatus as claimed in claim 7 , wherein said second control signal controls said second switch to connect said power source to said battery and said load if said voltage of said battery is less than an output voltage of said power source.
9. The apparatus as claimed in claim 7 , wherein said second control signal controls said second switch to disconnect said power source from said battery and said load if said voltage of said battery is greater than an output voltage of said power source.
10. The apparatus as claimed in claim 4 , wherein
said power source provides power to said battery and said load in said charging state, and
said battery provides power to said load in said discharging state.
11. An electric vehicle comprising:
a load configured to receive power from a power source or a battery;
a control circuit, coupled to said load, configured to manage said power by using a first control signal and a second control signal, said first control signal being generated by said control circuit based on a current of said battery, said second control signal being generated by said control circuit based on a voltage of said battery; and
a first switch, coupled to said control circuit, configured to control connection of said battery to said power source and said load according to said first control signal,
wherein said first control signal controls a voltage at a terminal of said first switch to maintain said current of said battery to be substantially equal to a current setting, and said second control signal controls said battery to switch between a first state and a second state.
12. The electric vehicle as claimed in claim 11 , wherein
said first switch comprises a transistor, and
a voltage at a gate of said transistor is controlled by said first control signal.
13. The electric vehicle as claimed in claim 11 , wherein said control circuit comprises a current monitoring unit, coupled to said first switch, configured to detect said current of said battery and generate said first control signal to control said first switch.
14. The electric vehicle as claimed in claim 13 , wherein said current monitoring unit compares said current of said battery with said current setting and generates said first control signal based on the comparison to maintain said current to be substantially equal to said current setting.
15. The electric vehicle as claimed in claim 11 , wherein said first state is a charging state and said second state is a discharging state.
16. The electric vehicle as claimed in claim 11 further comprising a second switch, coupled to said first switch and said control circuit, configured to control connection of said power source to said battery and said load based on said second control signal.
17. The electric vehicle as claimed in claim 16 , wherein said control circuit comprises a voltage monitor unit, coupled to said second switch, configured to detect said voltage of said battery and generate said second control signal to control said second switch.
18. The electric vehicle as claimed in claim 15 , wherein
if said voltage of said battery is less than a start-up voltage threshold of said load, then said second control signal controls said battery to operate in said charging state, and said power source provides said current to charge said battery via said first switch and provides power to said load; and
if said voltage of said battery is greater than an output voltage of said power source, then said second control signal controls said battery to operate in said discharging state, and said battery provides power via said first switch to said load.
19. The electric vehicle as claimed in claim 15 , wherein
said power source provides power to said battery and said load in said charging state, and
said battery provides power to said load in said discharging state.
20. A method for managing power in an electric vehicle, said method comprising:
generating a first control signal based on a current of a battery operable for powering said electric vehicle;
generating a second control signal based on a voltage of said battery;
controlling, using a control circuit, connection of said battery to a power source and a load in said electric vehicle by controlling a switch based on said first control signal;
maintaining said current of said battery to be substantially equal to a current setting by controlling a voltage at a terminal of said switch according to said first control signal; and controlling said battery to switch between a first state and a second state according to said second control signal.
21. The method as claimed in claim 20 , wherein
said switch comprises a transistor; and
said controlling of said connection comprises controlling a voltage at a gate of said transistor according to said first control signal.
22. The method as claimed in claim 20 , wherein said first state is a charging state and said second state is a discharging state.
23. The method as claimed in claim 22 , further comprising controlling connection of said power source to said battery and said load based on said second control signal to control said battery to switch between said charging state and said discharging state.
24. The method as claimed in claim 20 , wherein said maintaining comprises adjusting the conduction of said switch if said current is greater than said current setting.
25. The method as claimed in claim 23 , wherein said controlling of said battery to switch between said charging state and said discharging state comprises:
controlling said battery to operate in said charging state if said voltage of said battery is less than a start-up voltage threshold of said load, wherein in said charging state, said power source provides said current to charge said battery via said first switch and provides power to said load; and
controlling said battery to operate in said discharging state if said voltage of said battery is greater than an output voltage of said power source, wherein in said discharging state, said battery provides power to said load and a discharging current flows from said battery through said switch to said load.