Electric power conversion apparatus

An electric power conversion apparatus comprising:

• a rectifier circuit configured to rectify an alternating current output from a single phase AC power source;
• an inverter circuit including a plurality of switches and being configured to
• convert a direct current output by the rectifier circuit into an alternating current by a switching operation of the switches and
• supply the alternating current to a load;
• a DC link capacitor connected between input nodes of the inverter circuit and having a capacitance value set so as to
• allow a fluctuation in an output voltage of the rectifier circuit and
• suppress a ripple voltage caused by the switching operation;
• a reactor connected between the rectifier circuit and the inverter circuit or between the AC power source and the rectifier circuit;
• a control unit including a microcomputer and a memory, the control unit being configured to control the inverter circuit so as to have a non conduction period during which a current does not flow from the AC power source to the rectifier circuit;
• and
• a resonance suppression unit including one of the first inverter circuit and a resonance suppression circuit, the resonance suppression unit
• being connected in parallel to the DC link capacitor,
• including at least one switch, and
• being configured to suppress LC resonance of a circuit including the DC link capacitor and the reactor,
• the control unit being configured to operate the resonance suppression unit to attenuate a physical quantity correlated with a pulsation of magnetic energy of the reactor due to the LC resonance by more than 80% in a resonance suppression period of three cycles of the LC resonance starting from a transition timing for a transition from the non conduction period to a conduction period during which the current flows from the AC power source to the rectifier circuit.

An electric power conversion apparatus comprising:

• a rectifier circuit configured to rectify an alternating current output from an AC power source of three phases;
• an inverter circuit including a plurality of switches and being configured to
• convert a direct current output by the rectifier circuit into an alternating current by a switching operation of the switches and
• supply the alternating current to a load;
• a DC link capacitor connected between input nodes of the inverter circuit and having a capacitance value set so as to
• allow a fluctuation in an output voltage of the rectifier circuit and
• suppress a ripple voltage caused by the switching operation;
• a reactor connected between the rectifier circuit and the inverter circuit or between the AC power source and the rectifier circuit;
• a control unit including a microcomputer and a memory, the control unit being configured to control the inverter circuit so as to have a non conduction period during which a current of a predetermined phase among the three phases does not flow from the AC power source to the rectifier circuit;
• and
• a resonance suppression unit including one of the first inverter circuit and a resonance suppression circuit, the resonance suppression unit
• being connected in parallel to the DC link capacitor,
• including at least one switch, and
• being configured to suppress LC resonance of a circuit including the DC link capacitor and the reactor,
• the control unit being configured to operate the resonance suppression unit to attenuate a physical quantity correlated with a pulsation of magnetic energy of the reactor due to the LC resonance by more than 80% in a resonance suppression period of three cycles of the LC resonance starting from a transition timing for a transition from the non conduction period to a conduction period during which the current of the predetermined phase flows from the AC power source to the rectifier circuit.