Abstract：The traditional dual-output converter has two identical configuration converters in parallel, using twice the number of switches and driving circuits. It can lead to an increase in size and cost. Therefore, compact dual-output converters for reducing the switch number are getting more and more attention, which couple the circuits of two converters and share some branches or switches. The dual-output converter topology comprises the existing common-parallel-phase approach or the switch-multiplexing method. However, connecting two output terminals in series has a limited modulation index of two outputs, resulting in low utilization of the DC link voltage and a complicated control scheme. Therefore, based on the ANPC-TLC topology, this paper proposes a dual-output active-neutral-point-clamped three-level converter (DO-ANPC-TLC) topology. This topology has two three-phase AC voltage output ports by adding two extra switches per phase. The proposed converter changes the traditional series connection of the two output terminals to a parallel connection so that the modulation index of two outputs does not affect each other. Both sets of outputs can achieve the maximum modulation index under the same or different frequency conditions, which improves the DC link voltage utilization. Firstly, the DO-ANPC-TLC topology is described in detail. Based on the ANPC-TLC topology, the proposed topology utilizes only two extra switches per phase to form the second output port of the converter, and its modulation index is not affected by the first output port. The operating principle of the converter is analyzed, and its current paths, output phase voltage levels, and blocking voltages of each switch in different switching states are studied. Secondly, considering the structure characteristics and operating principle of DO-ANPC-TLC, a dual-output virtual space vector pulse-width modulation (DO-VSVPWM) method is investigated, which can control two sets of AC outputs independently and keep the neutral point voltage balance. To further simplify the control process, a carrier-based simplified dual-output virtual space vector pulse width modulation (CB-VSVPWM) strategy is studied. The CB-VSVPWM simplifies the modulation by avoiding the small zone judgment, duty ratio calculation, and switching sequence listing process in each small zone. Finally, the device loss distribution and the total voltage and current harmonic distortion (THD) of the proposed DO-ANPC-TLC are analyzed. The DO-ANPC-TLC prototype is built and tested in common frequency (CF) and different frequency (DF) modes. The results indicate that (1) The line-voltage of the two outputs is five-level, and the line-voltage harmonics are mainly distributed around the switching frequency and its multiples. (2) The voltages of two capacitors can be balanced and stable at around 100V in different modes. (3) The conversion efficiency of the converter reaches its maximum value of 96.6% at the modulation index of 1. The proposed topology’s feasibility and the modulation scheme’s effectiveness are verified.
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2024, Vol. 39 
