The parallel multiplex matrix converter couples in parallel at least two matrix converters, each of which PWM-controls bidirectional switches coupling input phases from an AC power supply to each output phases so as to output an arbitrary AC voltage or DC voltage. The method includes forming a plurality of housings. A voltage signal collecting unit is provided on a top of the main beam for directly collecting the measured voltage signals to obtain a voltage state of the fuel cell. The bridge vias correspond to adjacent discontinuous sections of the data line or the gate line. The solvent, which is caustic to the photomasks, removes the contaminants from the adhesive ring.