Abstract: A grid voltage phase detector includes: a d-q transformation unit for receiving a three-phase signal and producing a signal on d axis and a signal on q axis; a phase signal producing unit for producing a signal for phase synchronization of grid voltage from the signal on d axis and the signal on q axis; and a PR filtering unit, with a first filter having no change in magnitude and phase at a rated frequency, a second filter introducing 90° phase lead at a rated frequency, a third filter introducing 90° phase lag, and a fourth filter having no change in magnitude and phase at a rated frequency, for removing unbalanced components and harmonic components from the signal on d axis and the signal on q axis produced by the d-q transformation unit and providing the signals to the phase signal producing unit.

Abstract: A startup method of a semiconductor transformer, according to the present invention, comprises: a link capacitor initiating step in which a control unit controls a link capacitor voltage of a link capacitor between an AC/DC converter and a DC/DC converter connected thereto in series to reach an initial reference value, and stores link power; an output capacitor initiating step in which the control unit controls an output capacitor voltage of an output capacitor configured in an output of the DC/DC converter to reach an initial reference value, and stores output power; a link capacitor stabilizing step in which the control unit controls the link capacitor such that the link capacitor voltage of the link capacitor reaches a stable reference value; and an output capacitor stabilizing step in which the control unit controls the output capacitor such that the output capacitor voltage of the output capacitor reaches a stable reference value.

Abstract: A method for determining a scheme for converting power in every power conversion control period and converting power according to the determined scheme may comprise the steps of: calculating average power in a transformer inductor at the time of power conversion according to an SPWM scheme in a control period; calculating average power in the transformer inductor at the time of power conversion according to a DPWM scheme in a control period; and converting power according to a scheme by means of which the calculated average power of the transformer inductor is greater. Here, in the step of calculating the average power in the transformer inductor at the time of power conversion according to the DPWM scheme, it is possible to select a DPWM scheme with the maximum duty in a step-up or step-down condition given in the control period.

Abstract: Provided are a device and method for SoC balance control for a delta structure semiconductor transformer-based energy storage device, for operating a charging and discharging time of a system by controlling balance of battery SoC of a PCS connected by a delta connection so as to prevent overdischarging and overcharging of a specific battery, controlling a zero-phase-sequence component of the delta connection to balance the battery SoC for each phase, and controlling balance of an individual battery SoC. The device for SoC balance control for a delta structure semiconductor transformer-based energy storage device of the present invention is composed of an SoC balance control device that controls charging and discharging of a battery such that, in a PCS that performs charging and discharging from three-phase AC power, an A-phase, a B-phase, and a C-phase PCS connected by a delta connection, and the battery SoC of the PCS, are balanced.

Abstract: A grid voltage phase detector includes: a d-q transformation unit for receiving a three-phase signal and producing a signal on d axis and a signal on q axis; a phase signal producing unit for producing a signal for phase synchronization of grid voltage from the signal on d axis and the signal on q axis; and a PR filtering unit, with a first filter having no change in magnitude and phase at a rated frequency, a second filter introducing 90° phase lead at a rated frequency, a third filter introducing 90° phase lag, and a fourth filter having no change in magnitude and phase at a rated frequency, for removing unbalanced components and harmonic components from the signal on d axis and the signal on q axis produced by the d-q transformation unit and providing the signals to the phase signal producing unit.

Abstract: A method for determining a scheme for converting power in every power conversion control period and converting power according to the determined scheme may comprise the steps of: calculating average power in a transformer inductor at the time of power conversion according to an SPWM scheme in a control period; calculating average power in the transformer inductor at the time of power conversion according to a DPWM scheme in a control period; and converting power according to a scheme by means of which the calculated average power of the transformer inductor is greater. Here, in the step of calculating the average power in the transformer inductor at the time of power conversion according to the DPWM scheme, it is possible to select a DPWM scheme with the maximum duty in a step-up or step-down condition given in the control period.