Power supply device and power supply system

A power supply device, comprising:

• a transformer that has a primary winding and a secondary winding, a first voltage being intermittently applied to the primary winding, a second voltage being induced at the secondary winding in accordance with the applied first voltage;
• a rectification smoothing circuit that is located at a secondary side of the transformer, that has a positive output end and a negative output end, and that rectifies and smoothes the second voltage so as to generate a direct current voltage between the positive output end and the negative output end;
• a positive output terminal and a negative output terminal that are located at the secondary side of the transformer and that output the direct current voltage;
• a serial connection terminal to which another power supply device is connectable, the serial connection terminal being located at the secondary side of the transformer;
• a reverse flow prevention rectifying device that is located at the secondary side of the transformer;
• and
• a bypass rectifying device that is located at the secondary side of the transformer, wherein
• the serial connection terminal is connected to the negative output end,
• the positive output terminal is connected to the positive output end,
• the reverse flow prevention rectifying device is connected between the negative output end and the negative output terminal, and a forward direction of the reverse flow prevention rectifying device is toward the negative output end, and
• the bypass rectifying device is connected between the positive output end and the negative output end, and a forward direction of the bypass rectifying device is toward the positive output end.

A power supply device, comprising:

• a transformer that has a primary winding and a secondary winding, a first voltage being intermittently applied to the primary winding, a second voltage being induced at the secondary winding in accordance with the applied first voltage;
• a switching element that performs a switching operation so as to intermittently apply the first voltage to the primary winding;
• a rectification smoothing circuit that is located at a secondary side of the transformer, that has a positive output end and a negative output end, and that rectifies and smoothes the second voltage so as to generate a direct current voltage between the positive output end and the negative output end;
• a positive output terminal and a negative output terminal that are located at the secondary side of the transformer and that output the direct current voltage;
• an auxiliary power supply circuit to which the first voltage is input, the auxiliary power supply circuit generating an auxiliary voltage based on the first voltage;
• a bypass rectifying device that is connected between the positive output end and the negative output end, a forward direction of the bypass rectifying device being toward the positive output end;
• a factor detection circuit that is operated by using the auxiliary voltage as an operation power source and that detects a factor of the bypass rectifying device;
• a cooling device that is operated by using the auxiliary voltage as an operation power source and that cools an inside of the power supply device;
• and
• a control circuit that is operated by using the auxiliary voltage as an operation power source and that controls the cooling device, wherein
• when the factor being detected is equal to or less than a predetermined threshold value, the control circuit stops an operation of the cooling device, and
• when the factor being detected is more than the predetermined threshold value, the control circuit starts the operation of the cooling device.