Permanent magnet motor and washing machine provided therewith

A washing machine comprising:

• a permanent magnet motor;
• and
• a control unit which controls drive of the permanent magnet motor,
• wherein the permanent magnet motor includes a rotor including a rotor core and a plurality of permanent magnets provided inside the rotor core and establishing a plurality of magnetic poles;
• the permanent magnets include a plurality of types of permanent magnets having different coercive forces;
• said plurality of types of permanent magnets is disposed so that each one type constitutes one magnetic pole;
• one or more of the permanent magnets having relatively smaller coercive forces have:
• a first magnetic characteristic that when a magnetizing magnetic field is caused to act on the permanent magnets from a point in a second quadrant in a hysteresis loop showing a relationship between magnetic polarization and field intensity, a magnetic susceptibility is substantially at 0 until reaching an inflection point thereof during magnetization, and when exceeding the inflection point of the magnetic susceptibility during the magnetization to the magnetization side, the magnetic susceptibility enters a loop approximating to the hysteresis loop in a first quadrant;
• and
• a second magnetic characteristic that when a demagnetizing magnetic field is caused to act on the permanent magnets from a point in the first quadrant in said hysteresis loop, a magnetic susceptibility is substantially at 0 until reaching an inflection point thereof during demagnetization, and when exceeding the inflection point of the magnetic susceptibility during the demagnetization to a demagnetization side, the magnetic susceptibility enters a loop approximating to the hysteresis loop in a second quadrant;
• and
• the control is arranged so as to change a magnetization state of the permanent magnets having a relatively smaller coercive force.

A control unit that controls a permanent magnet motor, wherein:

• the permanent magnet motor includes a rotor including a rotor core and a plurality of permanent magnets provided inside the rotor core and establishing a plurality of magnetic poles;
• the permanent magnets include a plurality of types of permanent magnets having different coercive forces;
• said plurality of types of permanent magnets is disposed so that said one type constitutes one magnetic pole;
• one or more of the permanent magnets having relatively smaller coercive forces have:
• a first magnetic characteristic that when a magnetizing magnetic field is caused to act on the permanent magnets from a point in a second quadrant in a hysteresis loop showing a relationship between magnetic polarization and field intensity, a magnetic susceptibility is substantially at 0 until reaching an inflection point thereof during magnetization, and when exceeding the inflection point of the magnetic susceptibility during the magnetization to the magnetization side, the magnetic susceptibility enters a loop approximating to the hysteresis loop in a first quadrant;
• and
• a second magnetic characteristic that when a demagnetizing magnetic field is caused to act on the permanent magnets from a point in the first quadrant in said hysteresis loop, a magnetic susceptibility is substantially at 0 until reaching an inflection point thereof during demagnetization, and when exceeding the inflection point of the magnetic susceptibility during the demagnetization to a demagnetization side, the magnetic susceptibility enters a loop approximating to the hysteresis loop in a second quadrant;
• and
• the control unit is arranged so as to change a magnetization state of the permanent magnets having a relatively smaller coercive force.