Abstract: A vertical heat treatment apparatus includes a heat treatment unit for performing a heat treatment process to a semiconductor wafer using a gas and a gas supply unit for supplying the gas to the heat treatment unit. The gas supply unit includes a plurality of gas controlling instruments having a plurality of gas flow control devices, a gas controlling instruments-storage vessel for storing the instruments, and a plurality of electrical parts arranged outside the storage vessel and belonging to the instruments, and an electrical parts-storage vessel for storing the electrical parts, and the plurality of gas flow control devices are integrated with each other by block-like joints.

Abstract: A power inverter control device is designed to control a neutral point clamped power inverter apparatus including first to fourth self-extinction elements sequentially connected in series between two end terminals of a power supply having an intermediate terminal, four freewheeling diodes connected in parallel with the self-extinction elements in a direction opposite thereto, a series circuit of first and second clamping diodes, connected in parallel with a series circuit of the second and third self-extinction elements in a direction opposite thereto and having a node connected to the intermediate terminal of the power supply.

Abstract: A high frequency link power converter apparatus includes a power source, a circulating current type AC-AC converter having an output terminal connected to the power source, a high frequency phase-advancing capacitor connected to an input terminal of the AC-AC converter, a phase controller for controlling a firing phase of the AC-AC converter, an external oscillator for supplying phase reference signals to the phase controller, a first circuit for controlling a crest value of voltages applied to the phase-advancing capacitor, a second circuit for detecting a phase difference between the reference signals and the voltages applied to the phase-advancing capacitor, and a third circuit for controlling the phase difference, so that the magnitude of the phase difference becomes substantially zero.