25-04-2014, 03:00 PM
MPPT and Voltage Balancing ControlWith Sensing Only Inductor Current For PV-Fed Three-Level Boost-Type Converters
MPPT and Voltage Balancing .pdf (Size: 485.88 KB / Downloads: 13)
Abstract
In the literature, both PV voltage and PV current
need to be sensed to perform maximum power point tracking
(MPPT) control. For three-level boost converter, both capacitor
voltages need to be sensed and an additional voltage balancing
control loop is required to balance the capacitor voltages. In this
paper, the MPPT control and the voltage balancing control with
sensing only inductor current is proposed. The provided
simulation and experimental results demonstrate the proposed
method.
INTRODUCTION
he three-level boost-type converters have the advantages of
the low voltage stress, the low inductor current ripple and
the low switching loss [1-2]. Therefore, the three-level boost
converters are widely used in the modern power electronics
applications, such as AC/DC PFC application [1-2], DC/DC
PV applications [3-5], the fuel-cell applications [6-7] and the
wind energy application [8].
For the PV-fed converter, sensing both PV current and PV
voltage is required to achieve the MPPT control. Additionally,
for three-level boost-type converter, sensing additional
capacitor voltages is also required to detect the voltage
imbalance and force both capacitor voltages to be balanced
[1,2,5,7,8].
Experimental Results
The proposed control method has been implemented in a
FPGA-based system with commercial FPGA XC3S200 chip.
The nominal parameters are the same as those in Table II and
Table III, but both capacitors in experiment have the same
nominal values 2200F . In practice, the mismatch of two real
capacitances and two equivalent series resistors (ESR) may
contribute to the voltage imbalance.
The experimental results with the proposed MPPT control
method and with the voltage balancing control loop are plotted
in Fig. 9(a) and Fig. 9(b), respectively. In Fig. 9(a), the initial
voltage imbalance is near 10V.
Conclusions
In this paper, the MPPT and the voltage balancing control
methods for three-level boost-type converter is proposed. By
the proposed sampling strategy, the information of the PV
power and the voltage imbalance can be provided for the
proposed control methods. The simulation and experimental
results show that the proposed methods with only sensing the
inductor current are able to achieve the desired functions. The
proposed methods reduce the sensor count and save the cost. In
addition, the proposed voltage balancing control loop can be
extended to other circuits which needs to avoid voltage
imbalance.