Motor-drive compressor

Abstract

A motor-driven compressor includes a compression portion, which compresses a fluid, an electric motor, which drives the compression portion, a drive circuit, which drives the electric motor, a temperature obtaining section, which obtains the temperature of the drive circuit, and a drive mode controller, which controls the drive mode of the drive circuit. The drive mode controller controls the drive mode based on the temperature obtained by the temperature obtaining section and at least one of the rotational speed and the modulation factor of the electric motor.

1 . A motor-driven compressor comprising:
 a compression portion, which compresses a fluid;   an electric motor, which drives the compression portion;   a drive circuit, which drives the electric motor and includes switching elements;   a temperature obtaining section, which obtains a temperature of the drive circuit; and   a drive mode controller, which controls a drive mode of the drive circuit, wherein   the drive mode includes   a first drive mode, the modulation method of which is three-phase modulation,   a second drive mode, the modulation method of which is two-phase modulation, and   a third drive mode, which has a carrier frequency lower than a carrier frequency of the first drive mode, the modulation method of the third drive mode being three-phase modulation, and   the drive mode controller controls the drive mode based on a temperature obtained by the temperature obtaining section and at least one of a rotational speed and a modulation factor of the electric motor.   
     
     
         2 . The motor-driven compressor according to  claim 1 , wherein
 in a situation in which the drive mode is the first drive mode, the drive mode controller shifts the drive mode from the first drive mode to the second drive mode based on the fact that a two-phase modulation condition, which is defined by at least one of the rotational speed and modulation factor, is met, and   in a situation in which the drive mode is the first drive mode, the drive mode controller shifts the drive mode from the first drive mode to the third drive mode based on the fact that the obtained temperature is higher than a predetermined third drive mode initiating temperature.   
     
     
         3 . The motor-driven compressor according to  claim 2 , wherein
 the third drive mode initiating temperature is a primary third drive mode initiating temperature,   in a situation in which the drive mode is the second drive mode, the drive mode controller shifts the drive mode from the second drive mode to the third drive mode based on the fact that a predetermined third drive mode shifting condition is met,   the third drive mode shifting condition includes the obtained temperature being higher than a predetermined secondary third drive mode initiating temperature, and   the secondary third drive mode initiating temperature is higher than the primary third drive mode initiating temperature.   
     
     
         4 . The motor-driven compressor according to  claim 3 , further comprising a field weakening controller, which executes field weakening control on the electric motor when a predetermined field weakening condition is met, and
 the third drive mode shifting condition is met when the obtained temperature is higher than the secondary third drive mode initiating temperature and the field weakening controller is not executing the field weakening control.   
     
     
         5 . The motor-driven compressor according to  claim 3 , wherein
 in a situation in which the drive mode is the third drive mode, the drive mode controller shifts the drive mode from the third drive mode to the first drive mode based on the fact that the obtained temperature is lower than a predetermined first drive mode initiating temperature,   in a situation in which the drive mode is the third drive mode, the drive mode controller shifts the drive mode from the third drive mode to the second drive mode based on the fact that the obtained temperature is lower than a predetermined second drive mode initiating temperature and the two-phase modulation condition is met, and   the first drive mode initiating temperature is lower than the second drive mode initiating temperature.   
     
     
         6 . The motor-driven compressor according to  claim 2 , wherein, in a situation in which the drive mode is the first drive mode, the drive mode controller shifts the drive mode from the first drive mode to the second drive mode when the two-phase modulation condition is met and the obtained temperature is higher than the third drive mode initiating temperature. 
     
     
         7 . The motor-driven compressor according to  claim 1 , wherein
 the electric motor is a three-phase motor, and   the drive circuit is a three-phase inverter.