A GaN compound semiconductor device can be capable of free process design and can have optimum device characteristics. There is included a long side mounting strip coupled to the passageway frame. The controlling of the HF inverter provides a freewheeling period in the HF inverter 3 each time the first freewheeling period is provided in the cyclo-converter. The first member includes a locking region. A stop abutment, mounted on the lower section of the vertical support piece, is firmly abutted to the inner side of the curved section of the horizontal support, so as to prevent it from sliding and fracture. The software instructions, when executed by the processor, cause the processor to cause the reserved quantity to decay based at least in part on at least one of the decay rule, the decay interval, the decay rate, and the decay quantity, and one or more conditions.