Abstract: A three-phase UPS control method and apparatus, and a three-phase uninterruptible power supply resolve a problem that after a zero wire is lost, when a current control method is applied to a three-phase UPS using a three-level topology, a 0-axis direct-current modulated wave results in that positive and negative buses are unbalanced. The method includes: determining that a zero wire of a three-phase uninterruptible power supply is lost; using an alternating current whose frequency is a harmonic frequency of mains as a 0-axis reference current; and generating a 0-axis modulated wave according to a difference between the 0-axis reference current and a 0-axis sampling current, to control a rectifier in the three-phase uninterruptible power supply to convert a received alternating current to a direct current.

Abstract: An inverter power supply system includes an inverter circuit and a feedback circuit, where the inverter circuit is configured to convert a first alternating current voltage into a second alternating current voltage, and convert a first alternating current into a second alternating current; the feedback circuit determines whether a value of the second alternating current voltage exceeds a preset threshold; and when the value of the second alternating current voltage exceeds the preset threshold, the feedback circuit acquires a feedback current, compensates for a reference value of the first alternating current according to the feedback current, generates a control signal according to a reference value, after compensation, of the first alternating current, and outputs the control signal to the inverter circuit to adjust the value of the second alternating current voltage.

Abstract: A three-phase UPS control method and apparatus, and a three-phase uninterruptible power supply resolve a problem that after a zero wire is lost, when a current control method is applied to a three-phase UPS using a three-level topology, a 0-axis direct-current modulated wave results in that positive and negative buses are unbalanced. The method includes: determining that a zero wire of a three-phase uninterruptible power supply is lost; using an alternating current whose frequency is a harmonic frequency of mains as a 0-axis reference current; and generating a 0-axis modulated wave according to a difference between the 0-axis reference current and a 0-axis sampling current, to control a rectifier in the three-phase uninterruptible power supply to convert a received alternating current to a direct current.

Abstract: An inverter power supply system includes an inverter circuit and a feedback circuit, where the inverter circuit is configured to convert a first alternating current voltage into a second alternating current voltage, and convert a first alternating current into a second alternating current; the feedback circuit determines whether a value of the second alternating current voltage exceeds a preset threshold; and when the value of the second alternating current voltage exceeds the preset threshold, the feedback circuit acquires a feedback current, compensates for a reference value of the first alternating current according to the feedback current, generates a control signal according to a reference value, after compensation, of the first alternating current, and outputs the control signal to the inverter circuit to adjust the value of the second alternating current voltage.