Circuit Configuration and Operation Principle of Electrical Insulation Circuit for AC Fed Transformer-less Electric Vehicles Using High Withstand Voltage Property of SiC Power Module

Experimental verification of isolation power circuit for transformer‐less AC fed electric vehicles

“…As a first step, a flying capacitor circuit was proposed to transmit power between DC input and output without simultaneous conduction (below referred to as "conventional circuit"); the applicability of the circuit to AC trains was demonstrated via mini-model experiments. 11,12 As a second step, capacitive isolation 13 using a nesting capacitor structure was proposed, 14 and a similar circuit was incorporated into the conventional circuit to obtain a basic configuration for insolation between DC input and output 15 (below referred to as "isolation circuit"). In Reference [15], operation principle of the isolation circuit during powering and regeneration was demonstrated, and the feasibility of power transfer was confirmed via circuit response analysis in every mode.…”

“…11,12 As a second step, capacitive isolation 13 using a nesting capacitor structure was proposed, 14 and a similar circuit was incorporated into the conventional circuit to obtain a basic configuration for insolation between DC input and output 15 (below referred to as "isolation circuit"). In Reference [15], operation principle of the isolation circuit during powering and regeneration was demonstrated, and the feasibility of power transfer was confirmed via circuit response analysis in every mode.…”

“…ISOLATION CIRCUIT 15 A configuration example of the transformer-less AC traction circuit is shown in Figure 3 (one-car portion). Using the same approach as shown in fig.…”

“…The diodes connected in antiparallel to the reverse-blocking switches turn off when capacitor currents i a , i b are zero, thus realizing ZCS operation (Figure 5). The same operation principle applies to powering and regeneration; the principle is explained below by an example of powering Mode 3① in Table 1( [15]); terminating voltage v c2 is positive. According to Reference [15], the on-period T 1 of S 1 and S 2 to provide ZCS with i a = 0 is as shown below.…”

“…The same operation principle applies to powering and regeneration; the principle is explained below by an example of powering Mode 3① in Table 1( [15]); terminating voltage v c2 is positive. According to Reference [15], the on-period T 1 of S 1 and S 2 to provide ZCS with i a = 0 is as shown below.…”