Patent ID: 9136788
Filing Date: 2015-09-15
Classification: B60L,F04C,H02P,Y02T

Abstract:
1. An air compressor comprising: a compressor main body including a rotor for compressing air; a synchronous motor for driving the compressor main body; a motor control section for controlling a rotational speed of the synchronous motor; and an oil supply section for supplying oil to the compressed air, wherein the air compressor includes a temperature sensor for detecting a temperature of the oil; wherein the motor control section is programmed to perform a positioning operation for causing a DC current to start rotation of the rotor by flowing through a given phase of an armature winding included in the synchronous motor at the time of the startup of the compressor main body; wherein, in the positioning operation, a magnitude of the DC current is changed so that a first DC current flows in the synchronous motor if a temperature detected by the temperature sensor is equal to or less than a preset temperature and a second DC current flows in the synchronous motor if the temperature detected by the temperature sensor is more than the preset temperature; wherein, after the positioning operation, a synchronous operation is performed with either the first DC current or the second DC current that flows in the positioning operation until the rotational speed which can stabilize a position-sensor-free control of the synchronous motor is reached; and wherein the position-sensor-free control is performed after the synchronous operation is performed.