Abstract
This paper presents a robust control technique for three-phase chargers under unbalanced grid conditions. The control method consists of inner-loop robust grid-current control and outer-loop proportional integral control for constant current (CC) and constant voltage (CV) control. A dual-current control for the inner-loop positive and negative sequence is employed to eliminate the unbalanced current caused by the grid so that a constant current and voltage can be provided to the batteries. The inner-loop robust controllers utilize state feedback with integral action in the dq-synchronous frame. A linear matrix inequality-based optimization scheme is used to determine stabilizing gains of the controllers to maximize the convergence rate to steady state in the presence of uncertainties. The uncertainties of the system are described as the potential variation range of the inductance and resistance in the L-filter.
Highlights
With the emergence of enormous amounts of plug-in hybrid electric vehicles (PHEVs) and electric vehicles (EVs) and the flourishing of renewable energy, the development of power storage has become an interesting topic
The control method consists of inner-loop robust grid-current control and outer-loop proportional integral control for constant current (CC) and constant voltage (CV) control
A dual-current control for the inner-loop positive and negative sequence is employed to eliminate the unbalanced current caused by the grid so that a constant current and voltage can be provided to the batteries
Summary
With the emergence of enormous amounts of plug-in hybrid electric vehicles (PHEVs) and electric vehicles (EVs) and the flourishing of renewable energy, the development of power storage has become an interesting topic. Model predictive control (MPC) has been proposed in [3] for a bidirectional three-phase charger This method could provide bidirectional power transfer with instantaneous mode charging capability and fast dynamic response. The controller outputs the optimum pulse width modulation (PWM) switching signal to provide the nearest output reference with fast convergence rate to the equilibrium point whose power factor is unity This method requires a DC/DC converter to maintain the CC/CV charging stage. In [7,10], three operational modes for bidirectional chargers i.e., grid-to-vehicle (G2V), vehicle-to-grid (V2G), and vehicle-to-home (V2H) were considered to provide a full bidirectional charger capability for electric vehicles These methods adopt classical controllers such as PI which require multi-loop gain tunings. The conventional phase-locked loop (PLL) method is considered in this paper to obtain the grid voltage phase angle
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