DAB converters are used to build the power exchange converter circuits. Several of these may be connected on the primary side that connects to the DC bus. The secondary side is connected to either batteries or supercapacitors connected in parallel through the DAB. Asymmetric operation of the individual modules is allowed as long as the primary side voltage limits are not exceeded.
The control variable is the phase difference between the primary and secondary sides of the bridge. The power goes from the leading phase side to the lagging phase side. A PI controller is used to control the power flow between the DC bus and the power bank. A resonance can be triggered due to the inductance and capacitance in parallel, therefore you need state-feedbak is used for the capacitance-voltage. The transfer function is
$$\frac{\theta(s)}{I_L(s)}=\frac{K_{DAB}}{LCs^2+K_{DAB}K_CLs+1}$$
As the damping term appears in the denominator, active damping is achieved without resistance. This avoids losses.
[[Stern-Tafel Supercapaitor Model]] – used in this system
- chenComprehensiveRealTimeHardwareIntheLoop2020
Backlinks:
[[Battery Modeling]]
[[Battery System]]
[[LC Circuit]]
Phase Lag
[[PI Controller]]
[[Second-Order Systems]]
State Feedback
[[Submarine Energy Storage System]]
[[Supercapacitor]]