Control strategy for the front-end DC-DC converter to reduce the second-order harmonic current in the two-stage inverter

Abstract

The instantaneous output power of the two-stage single-phase inverter pulsates at twice the output voltage frequency, generating second-order harmonic current (SHC) in the front-end DC-DC converter. To reduce the SHC, this paper proposes a control strategy based on the virtual impedance. For the case that adopting a resistor as the virtual impedance, a closed-loop parameter design method is presented, indicating that this instance is not beneficial to increasing the voltage loop crossover frequency (VLCF). To overcome this problem, a control strategy with inner inductor current feedback through the band-pass filter(BPF) is put forward and a damping resistor is added into the BPF in order to improve the stability margin. The proposed control strategy can not only reduce the SHC significantly, but also improve the dynamic performance of the front-end DC/DC converter effectively while guarantee the converter working in stability. Finally, an 1kVA prototype is built and tested in the lab. The experimental results are given to verify the effectiveness of the proposed control strategy.

Second Ripple Current Suppression by Two Bandpass Filters and Current Sharing Method for Energy Storage Converters in DC Microgrid

“…From Fig. 5, the virtual resistances R droopj can change into the fine tuning virtual resistances R' droopj by using (17) to (21). Meanwhile, the output voltages of parallel ESCs are equivalent when the fine tuning virtual resistances are introduced into parallel ESCs.…”

“…In [20], an advanced active control technique has been proposed to incorporate a current control loop in the DC/DC converter for ripple reduction, but the dynamic performance needs to be further improved. The inductance current feedback control method by single BPF has been proposed in [21], which can reduce the closed-loop impedance of the ESC at non-double output voltage frequency and improve the dynamic performance of the system at the load mutation by the BPF, but due to select range limitation of the quality factor, the closed-loop impedance of the ESC at double output voltage frequency in [21] is lower than that in [22]. So, the SRC is less reduced.…”

“…So, the SRC is less reduced. The capacitance voltage feedback control method by single BPF has been proposed in [22], it effectively reduces the SRC, but there is no single BPF in the inductance current feedback, the closed-loop impedance of the ESC at non-double output voltage frequency in [22] is higher than that in [21], weakening the dynamic performance of the system at the load mutation.…”

Control Strategies and Power Decoupling Topologies to Mitigate 2ω-Ripple in Single-Phase Inverters: A Review and Open Challenges

“…According to [28], a current ripple more than 8% may badly affect the electrodes and electrolyte of the battery and reduces the performance and efficiency of the system. Moreover, ripple increases the voltage/current stress on the system components [34], [35].…”

A Bandpass Filter Incorporated Into the Inductor Current Feedback Path for Improving Dynamic Performance of the Front-End DC–DC Converter in Two-Stage Inverter

“…The SHC will lead to increased current stress in power switches and increased conduction losses in both power switches and magnetic components [5], [6]. If soft-switching technique is adopted in the dc-dc converter, the SHC will narrow down the soft-switching range, thus adversely reducing the overall system efficiency.…”