Relay welding detection device, power supply control device including same, and welding detection method

A relay welding detection device to be applied to a vehicle, the vehicle including:

• a direct-current power supply including a first terminal and a second terminal both connected to a load;
• a first relay disposed on a first wiring line connecting the first terminal to the load;
• a second relay disposed on a second wiring line connecting the second terminal to the load;
• a first resistor including a first end connected to a portion of the first wiring line between the first relay and the load, and a second end connected to a ground;
• and
• a second resistor including a first end connected to a portion of the second wiring line between the second relay and the load, and a second end connected to the ground;
• the relay welding detection device comprising:
• a voltage generator configured to generate a voltage, the voltage generator connected to the ground;
• a first resistor string including two resistors connected to each other in series at a first connection point, the first resistor string being connected in series to the voltage generator and the first terminal of the direct-current power supply between the voltage generator and the first terminal of the direct-current power supply;
• a second resistor string including two resistors connected to each other in series at a second connection point, the second resistor string being connected in series to the voltage generator and the second terminal of the direct-current power supply between the voltage generator and the second terminal of the direct-current power supply;
• a first switch configured to switch between a first connected state and a first disconnected state, the first resistor string being connected to the first terminal in the first connected state, and the first resistor string being disconnected from the first terminal in the first disconnected state;
• a second switch configured to switch between a second connected state and a second disconnected state, the second resistor string being connected to the second terminal in the second connected state, and the second resistor string being disconnected from the second terminal in the second disconnected state;
• and
• a relay welding detector connected to the ground, and configured to detect a first potential at the first connection point of the first resistor string and a second potential at the second connection point of the second resistor string,
• wherein the relay welding detector is configured to detect the first potential at the first connection point of the first resistor string in a case where the first switch is in the first connected state and the second switch is in the second disconnected state, and detect presence or absence of welding in the first relay and the second relay based on the first potential, a first determination value using a resistance value of the first resistor, and a second determination value using a resistance value of the second resistor.