DQ current control of a bidirectional, isolated, single-stage AC-DC converter for vehicle-to-grid applications

Abstract

Electric vehicles can provide a viable network of distributed energy storage and provide ancillary services to the grid, (Vehicle-to-Grid, V2G), but Electric Vehicle chargers need to be bidirectional in order to provide power back to the grid. In this paper, dq current control is proposed using a novel bidirectional, isolated, single stage AC-DC converter. Unity open loop power factor has been achieved in previous work using the novel topology but relies on a non-distorted voltage waveform to achieve unity power factor and lacks control of reactive power. The single phase input filter equations are transformed into the rotating dq reference frame by generating an imaginary beta axis. The filter dynamics are analyzed and controllers are designed for dq input currents. A phase shift component is added to the modulation scheme allowing control of the phase and magnitude of the converters input current. The topology and control scheme is simulated in PLECS. Simulation results are presented for various operating points and validate the theoretical analysis. The proposed control strategy implements real and reactive power control which is essential for V2G applications and the topology has the advantages of high switching frequency, isolation, voltage matching, high power density, and reduced size compared to the conventional cascaded isolated AC-DC topologies.

DQ current control of a bidirectional, isolated single-stage AC-DC converter

“…In order to control the phase shift of the input current, φ m (t) is introduced into the duty ratio equation and (3) becomes (5) [11]. The constants are combined into a gain term, K b (6).…”

“…By substituting (9) into (8) for i m (t), i s (t), and v s (t) the rotating reference frame equations for the active current, i md (t), and reactive current, i mq (t), are achieved, (10) and (11). The rotating reference frame is locked to the input voltage angular frequency, w s , which results in the voltage, v sq (t), equaling zero.…”

DC ripple current rejection in a bidirectional SiC single-phase AC-DC converter for V2G application

“…(1) From [14], the duty cycle d of the full bridge inverter is shown in (2) with a controllable phase angle 1Yi. The average source current Zi with a constant gain K b (3) is shown in (4).…”

“…Fig. 1: Topology of AC-DC Converter (9) The inverter leg a and leg b (10) are operated with a fixed duty cycle at 50% and phase shifted from the modulation used in [14]. The inverter leg c is operated with a duty cycle de (11) to modulate the magnitude and angle of the voltage Vz applied across the energy storage element.…”

“…The matrix converter applies Vi for the first 5/-ls interval and then applies -Vi for the next 5/-ls interval. The half-bridge leg a and leg b operate at a fixed 50% duty cycle with phase shift modulation [14]. The magnitude Vz and the phase angle cPv are calculated from (14), (15) and the half bridge inverter leg c is operated with duty cycle de (16).…”