Overcurrent protection device and charging device
An overcurrent protection device includes a first input terminal, a second input terminal, a first output terminal, a second output terminal, a breaker, a current sensor, and a comparator. A positive terminal and a negative terminal of a power source are connected to the first input terminal and the second input terminal. The second output terminal is connected to the second input terminal. The breaker includes a switch connected between the first input terminal and the first output terminal and opening upon reception of an interrupt command signal. The current sensor measures a difference between a current flowing between the first input terminal and the first output terminal, and a current flowing between the second input terminal and the second output terminal. The comparator sends the interrupt command signal to the breaker when a measurement value of the current sensor exceeds a first current threshold value.
1 . An overcurrent protection device comprising:
a first input terminal that is connected to one of a positive terminal and a negative terminal of a power source;
a second input terminal that is connected to the other one of the positive terminal and the negative terminal;
a first output terminal;
a breaker including a switch that is connected between the first input terminal and the first output terminal and that is configured to open when receiving an interrupt command signal;
a second output terminal that is connected to the second input terminal;
a current sensor that is configured to measure a difference between a current flowing between the first input terminal and the first output terminal, and a current flowing between the second input terminal and the second output terminal; and
a comparator that is configured to send the interrupt command signal to the breaker when a measurement value of the current sensor exceeds a first current threshold value,
wherein the breaker includes a protection circuit that is configured to open the switch when a current that exceeds a second current threshold value that is higher than the first current threshold value flows through the switch, and
the protection circuit is separate and distinct from the current sensor and from the comparator.
2 . The overcurrent protection device according to claim 1 , wherein a response speed of the protection circuit is faster than a response speed of the comparator.
3 . The overcurrent protection device according to claim 1 , further comprising a sub-breaker including a sub-switch that is connected between the second input terminal and the second output terminal and that is configured to open when receiving the interrupt command signal, and a sub-protection circuit that is configured to open the sub-switch when a current that exceeds the second current threshold value flows, wherein
the comparator is configured to send the interrupt command signal to the breaker and the sub-breaker when the measurement value of the current sensor exceeds the first current threshold value.
4 . The overcurrent protection device according to claim 3 , wherein:
the protection circuit of the breaker is configured to send the interrupt command signal to the sub-breaker when detecting a current exceeding the second current threshold value; and
the sub-protection circuit of the sub-breaker is configured to send the interrupt command signal to the breaker when detecting a current exceeding the second current threshold value.
5 . A charging device comprising:
the overcurrent protection device according to claim 1 ;
a boost converter that includes a low voltage terminal and a high voltage terminal, and that is configured to boost a voltage of electric power input to the low voltage terminal, in which the first output terminal and the second output terminal are connected to a positive terminal and a negative terminal of the low voltage terminal, respectively, and in which a battery to be charged is connectable to the high voltage terminal; and
a protection ground line that connects a ground terminal of a device equipped with the battery, and a ground terminal of the power source.
6 . The overcurrent protection device according to claim 1 , wherein the comparator is an analog-to-digital circuit component performing a single task of comparing the measurement value of the current sensor and the first current threshold value, and an output of the comparator is the same node as a gate of the switch.