Relay driving circuit and battery system having the same
The present invention relates to a relay driving circuit and a battery system for generating a gate voltage for controlling ON/OFF of a pre-charge relay, and provides a relay driving circuit that controls electrical connection between an external device and a battery pack, including: a transistor that receives a control signal of an enable level to perform an ON operation; a first resistor having a first end connected to a positive electrode of the battery pack and a second end connected to the relay, by the ON operation of the transistor; and a second resistor connected between the second end of the first resistor and the external device, the relay receives power supplied from the battery pack in a ratio of a resistance value of the second resistor to a sum resistance value of the first resistor and the second resistor to perform an ON operation.
1 . A relay driving circuit that controls a relay to control an electrical connection between an external device and a battery pack, comprising:
at least one transistor configured to receive a control signal of an enable level to perform an ON operation;
a first resistor having a first end connected to a positive electrode of the battery pack and a second end connected to the relay, by the ON operation of the at least one transistor; and
a second resistor connected between the second end of the first resistor and the external device,
wherein the relay receives a gate voltage supplied from the battery pack by multiplying a voltage corresponding to power supplied from the battery pack and a ratio of a resistance value of the second resistor to a sum of resistance values of the first resistor and the second resistor to perform the ON operation, and
wherein the at least one transistor includes:
a first transistor including a base configured to receive the control signal from a battery management system (BMS) and an emitter terminal connected to ground; and
a second transistor including a base connected to the first transistor, an emitter terminal connected to the first resistor and a collector terminal connected to the battery pack.
2 . The relay driving circuit of claim 1 , further comprising
a Zener diode connected in parallel to the second resistor to maintain a level of a voltage between first and second ends of the second resistor.
3 . The relay driving circuit of claim 1 , wherein the first transistor is configured to receive the control signal of the enable level to perform on the ON operation, and
wherein the second transistor is configured to receive a voltage of a ground level when the first transistor is turned on to perform on the ON operation to electrically connect the positive electrode of the battery pack and the first resistor.
4 . A battery system, comprising:
a main relay configured to control an electrical connection between an external device and a battery pack;
a pre-charge relay connected in parallel to the main relay and configured to be turned on before the main relay is turned on, and turned off after a predetermined time elapses after the main relay is turned on;
a battery management system (BMS) that generates a control signal to control switching of the main relay and switching of the pre-charge relay; and
a relay driving circuit including a first relay driving circuit controlling ON/OFF of the pre-charge relay, by including at least one transistor that receives a first control signal of an enable level from the BMS to perform an ON operation, a first resistor having a first end connected to a positive electrode of the battery pack and a second end connected to the pre-charge relay by the ON operation of the at least one transistor, and a second resistor connected between the second end of the first resistor and the external device,
wherein the pre-charge relay receives a gate voltage supplied from the battery pack by multiplying a voltage corresponding to power supplied from the battery pack to a ratio of a resistance value of the second resistor to a sum of resistance values of the first resistor and the second resistor to perform the ON operation, and
wherein the at least one transistor includes:
a first transistor including a base configured to receive the control signal from the BMS and an emitter terminal connected to ground; and
a second transistor including a base connected to the first transistor, an emitter terminal connected to the first resistor and a collector terminal connected to the battery pack.
5 . The battery system of claim 4 , wherein the first relay driving circuit further includes a Zener diode connected to the second resistor in parallel to maintain a level of a voltage between respective ends of the second resistor.
6 . The battery system of claim 4 , wherein the first transistor is configured to receive the first control signal of the enable level to perform the ON operation, and
wherein the second transistor is configured to receive a voltage of a ground level when the first transistor is turned on to perform the ON operation to electrically connect the positive electrode of the battery pack and the first resistor.
7 . The battery system of claim 4 , wherein the pre-charge relay includes a MOSFET that receives power supplied from the battery pack through a gate terminal thereof to perform the ON operation.
8 . The battery system of claim 4 , further comprising a second relay driving circuit,
wherein the first relay driving circuit and the second relay driving circuit each receive a control signal from the BMS.
9 . The battery system of claim 8 , wherein the second relay driving circuit includes fewer transistors than the first relay driving circuit.
10 . The battery system of claim 4 , further comprising:
a first protection block located between the battery pack and the pre-charge relay; and
a second protection block located between the battery pack and the main relay.
11 . The battery system of claim 10 , wherein the pre-charge relay is connected in series to a third resistor, and
wherein the third resistor is located between the first protection block and the pre-charge relay.