Grid voltage imbalance easily leads to three phases of unequal active power output of delta-connected power conversion system (PCS). This further intensifies the imbalance of State-of-charge (SOC) of battery pack among three phases. Therefore

an inter-phase SOC equalization control strategy based on zero-sequence current is proposed. The active and reactive components of zero-sequence current are defined based on current split-phase control. Then

the linear correspondence between SOC deviation values and zero-sequence active power is established by the proportional controller

and based on this

the relationship matrix between the active and reactive components of the zero-sequence current and the SOC deviation values is constructed. Therefore

the zero-sequence current can be solved according to the SOC deviation values to achieve SOC phase-to-phase equalization control. The method only needs two SOC deviation values and the positive and negative sequence voltage amplitude of grid to obtain zero-sequence current directly. Therefore

the zero sequence current can be calculated in real-time and efficiently according to the unbalance degree of the power grid

to realize the phase- to-phase balance of SOC. Moreover

all quantities are DC components

and there are no complex calculations

such as triangular functions

so it is easy to realize in practical engineering. Meanwhile

the corresponding control methods are proposed for the inner-phase SOC equalization and battery second-order ripple current suppression. Finally

a 380V/100kW/15kW·h prototype was built

and the experimental results verify the effectiveness of the proposed control strategy. realize the phase-to-phase balance of SOC. Moreover

all quantities are DC components

and there is no complex calculations such as triangular function

so it is easy to realize in practical engineering. Meanwhile

the corresponding control methods are proposed for the inner-phase SOC equalization and the suppression of battery second-order ripple current. Finally

a 380V/100kW/15kW·h prototype was built and the experimental results verify the effectiveness of the proposed control strategy.