Switching power supply unit

A switching power supply unit, comprising:

• a transformer including a first transformer coil, a second transformer coil, and a third transformer coil, the transformer coils being magnetically coupled with one another,
• a first switching circuit disposed between the first transformer coil and a first DC power supply,
• a rectifier circuit disposed between the second transformer coils and a second DC power supply,
• a second switching circuit disposed between the third transformer coil and AC voltage input terminals,
• a power factor correction circuit disposed between the second switching circuit and the AC voltage input terminals, and configured to include a switching element, and
• a switching control section performing control such that when the first DC power supply is assigned higher priority in charging based on a AC input voltage inputted from the AC voltage input terminals, a switching duty ratio in the second switching circuit is set to be fixed, and a switching duty ratio in the first switching circuit is set to be variable, and when the second DC power supply is assigned higher priority in charging based on the AC input voltage, at least one of the switching duty ratio in the second switching circuit and a switching duty ratio in the switching element in the power factor correction circuit is set to be variable based on amount of charge of the second DC power supply, and the first switching circuit performs switching operation.

A switching power supply unit, comprising:

• a transformer including a first transformer coil, a second transformer coil, and a third transformer coil, the transformer coils being magnetically coupled with one another,
• a first switching circuit disposed between the first transformer coil and a first DC power supply, and configured to include bidirectional switches,
• a rectifier circuit disposed between the second transformer coil and a second DC power supply,
• a second switching circuit disposed between the third transformer coil and AC voltage input terminals, and
• a switching control section performing control such that when the first DC power supply is assigned higher priority in charging based on a AC input voltage inputted from the AC voltage input terminals, a switching duty ratio in the second switching circuit which acts as an inverter circuit is set to be fixed, and a switching duty ratio in the first switching circuit which acts as a rectifier circuit is set to be variable, thereby charge operation is performed to the first DC power supply while a DC voltage outputted from the first switching circuit is changed and amount of charge of the first DC power supply is adjusted, and limited charge operation is performed to the second DC power supply compared with the first DC power supply while a DC voltage outputted from the rectifier circuit is fixed, and when the second DC power supply is assigned higher priority in charging based on the AC input voltage, the switching duty ratio in the second switching circuit which acts as an inverter circuit is set to be variable, and when the first switching circuit which acts as a rectifier circuit performs switching operation, thereby charge operation is performed to the second DC power supply while a DC voltage outputted from the rectifier circuit is changed and amount of charge of the second DC power supply is adjusted, and charge operation is performed to the first DC power supply based on the DC voltage outputted from the first switching circuit.

A switching power supply unit, comprising:

• a transformer including a first transformer coil, a second transformer coil, and a third transformer coil, the transformer coils being magnetically coupled with one another,
• a first switching circuit disposed between the first transformer coil and a first DC power supply,
• a rectifier circuit disposed between the second transformer coils and a second DC power supply,
• a second switching circuit disposed between the third transformer coil and AC voltage input terminals,
• a power factor correction circuit disposed between the second switching circuit and the AC voltage input terminals, and configured to include a switching element, and
• a switching control section performing control such that when the first DC power supply is assigned higher priority in charging based on a AC input voltage inputted from the AC voltage input terminals, a switching duty ratio in the second switching circuit which acts as an inverter circuit is set to be fixed, and a switching duty ratio in the first switching circuit which acts as a rectifier circuit is set to be variable, thereby charge operation is performed to the first DC power supply while a DC voltage outputted from the first switching circuit is changed and amount of charge of the first DC power supply is adjusted, and limited charge operation is performed to the second DC power supply compared with the first DC power supply while a DC voltage outputted from the rectifier circuit is fixed, and when the second DC power supply is assigned higher priority in charging based on the AC input voltage, at least one of the switching duty ratio in the second switching circuit which acts as an inverter circuit and a switching duty ratio in the switching element in the power factor correction circuit is set to be variable, and when the first switching circuit which acts as a rectifier circuit performs switching operations, thereby charge operation is performed to the second DC power supply while a DC voltage outputted from the rectifier circuit is changed and amount of charge of the second DC power supply is adjusted, and charge operation is performed to the first DC power supply based on the DC voltage outputted from the first switching circuit.