Electric power conversion apparatus and electric power conversion system

An electric power conversion apparatus comprising:

• a first electric power terminal;
• a switching circuit coupled to the first electric power terminal;
• a transformer including a first winding and a second winding, the first winding being led to the switching circuit;
• a rectifying circuit coupled to the second winding and including one or more rectification switching devices;
• a smoothing circuit including a first inductor and a first capacitor, the first inductor having a first end and a second end, the first capacitor having a first end coupled to the second end of the first inductor, and a second end coupled to a reference node;
• an electric power regeneration circuit coupled to the rectifying circuit and configured to allow energy of a surge voltage that occurs in the rectifying circuit to be regenerated in the first capacitor;
• a control circuit configured to control an operation of each of the switching circuit, the rectifying circuit, and the electric power regeneration circuit;
• and
• a second electric power terminal including a first coupling terminal and a second coupling terminal, the first coupling terminal being coupled to the second end of the first inductor and the first end of the first capacitor, the second coupling terminal being coupled to the reference node, wherein
• the electric power regeneration circuit includes
• a diode circuit provided on a path coupling the rectifying circuit and a first node to each other, the diode circuit being configured to allow a current to flow toward the first node,
• a second capacitor having a first end coupled to the first node, and a second end coupled to the reference node,
• a first regeneration switching device having a first end coupled to the first node, and a second end coupled to a second node,
• a second regeneration switching device having a first end coupled to the second node, and a second end coupled to the reference node, and
• a second inductor and a first diode provided on a path coupling the second node and the first end of the first capacitor to each other,
• the control circuit is configured to, when a voltage at the first node increases and exceeds a threshold voltage, cause the first regeneration switching device to switch from off to on and cause the second regeneration switching device to switch from on to off,
• a first positive voltage and a first negative voltage are to alternately occur across the second winding, when an input voltage inputted to the first electric power terminal is within a normal operation voltage range, and
• the threshold voltage is higher than each of a voltage at the rectifying circuit corresponding to an average value of the first positive voltage and a voltage at the rectifying circuit corresponding to an average value of the first negative voltage.