Y-junction photonic power splitters are essential in photonic integrated circuits. In this paper, a tunable Y-junction splitter is introduced using a standard silicon-on-insulator platform. It features a single-point control mechanism of both the turnability of power splitting ratios and the non-volatility with optical phase change materials (O-PCMs). This nonvolatile Y-junction splitter has a broadband of 350 nm (from 1300 to 1650 nm) with an about 0.7 dB low insertion loss. Using the direct binary search (DBS) inverse design algorithm, a circular point was identified to fill the phase change material Sb₂S₃ within the coupling area of the Y-junction photonic power splitter. Six example power splitting ratios of 1.86, 1.70, 1.50, 1.34, 1.21, and 1.14 were realized under single-point control using phase changes at 1550 nm with a 0.35 dB low insertion loss. Furthermore, we also implemented a five-stage cascaded array, with the final stage consisting of 16 Y-junction splitters. These results are useful for significantly simplifying the control of photonic circuits.