For the cascaded power electronic transformer used in the battery energy storage system

this paper proposes the battery balancing and coordinated control strategies on the basis of multi-level hybrid pulse width modulation(HPWM). By using HPWM

the bidirectional power in submodule of cascaded H-bridge(CHB)can be regulated independently. Taking advantage of this feature

the proposed strategy can control different charging or discharging for the battery units

and thus state of charge(SOC)balancing can be achieved. Meanwhile

the total power reference requirement and low distortion of AC waveforms are satisfied. In order to reduce the DC-link voltage fluctuations caused by the nonlinear time-varying switching functions in HPWM and the varying power commands

a coordinated control strategy with feedforward of power reference and switching function of rectifier stage is presented for the DC-link voltage controller of isolated bidirectional DC/DC converter. Simulation and experimental results show that the proposed control strategy can achieve fast converging and balancing of battery SOC curves

high-performance control of bidirectional power and effective suppression of DC-link voltage ripple.