Electric motor and electrical apparatus equipped with same
View Patent ↗An electric motor includes a magnet rotor which is placed with an air gap interposed between it and a stator and has a magnetic pole portion formed from a plastic magnet which swells by hydrogen bonds, an inverter circuit, a DC-voltage conversion portion, a driving logic control portion, a supply current value control portion, a current value designation portion, a reference current value designation portion, and a correlation designation portion, wherein the correlation designation portion determines an average current value by changing the average current value linearly or non-linearly with respect to a reference current value, and the magnetic pole portion absorbs moisture to swell, thereby making the air gap smaller, at higher humidity than a reference humidity.
1. An electric motor comprising:
a magnet rotor which is rotatably placed with an air gap interposed between the magnet rotor and a stator around which a driving coil is wound, the magnet rotor having a magnetic pole portion formed from a plastic magnet which swells by a hydrogen bond;
an inverter circuit including an upper-stage switching device and a lower-stage switching device which are connected to each other in a bridge manner;
a DC-voltage conversion portion which is formed from a chopper circuit adapted to apply a DC voltage to the inverter circuit;
a driving logic control portion adapted to supply the DC voltage generated by the DC-voltage conversion portion to the driving coils through the inverter circuit, in a successive full-wave energization manner according to a predetermined direction and in a predetermined order;
a supply current value control portion adapted to control an average current supplied to the inverter circuit to be constant;
a current value designation portion adapted to designate an average current value for which the supply current value control portion controls to be constant;
a reference current value designation portion adapted to set a reference current value to be designated by the current value designation portion, when the DC voltage generated by the DC-voltage conversion portion is a predetermined voltage; and
a correlation designation portion adapted to provide the current value designation portion with designation of a correlation between the reference current value and the average current value according to a voltage value of the DC voltage generated by the DC-voltage conversion portion, wherein
the correlation designation portion determines the average current value by changing the average current value linearly or non-linearly with respect to the reference current value, and
the magnetic pole portion absorbs moisture to swell to make the air gap smaller, at a higher humidity than a reference humidity.
2. The electric motor according to claim 1 , further comprising:
a reference current value designation change portion adapted to change designation of the reference current value designation portion; and
a torque-characteristic change portion adapted to designate a plurality of torque characteristics and to control the reference current value designation change portion.
3. The electric motor according to claim 2 , wherein the torque-characteristic change portion controls the reference current value designation change portion.
4. The electric motor according to claim 2 , further comprising a plurality of AC power-supply connection portions for connecting an AC power supply, wherein
the torque-characteristic change portion changes the torque characteristic depending on a position of connection to the AC power-supply connection portions.
5. The electric motor according to claim 1 , wherein
the magnetic pole portion is a plastic magnet containing polyamide 6 resin as a main binder.
6. The electric motor according to claim 5 , wherein
the plastic magnet is a polar anisotropic magnet.
7. The electric motor according to claim 1 , wherein
the driving logic control portion further includes a current waveform control portion for controlling the upper-stage switching device and the lower-stage switching device in a manner to bring the switching devices into a non-saturated state close to saturation.
8. The electric motor according to claim 1 , wherein
the DC-voltage conversion portion generates a designation voltage which designates an ON/OFF duty for performing PWM control of the switching devices, and
the driving logic control portion further includes a PWM control portion for performing PWM control of one of the upper-stage switching device and the lower-stage switching device based on the designation voltage.
9. An electrical apparatus equipped with the electric motor according to claim 1 .
10. The electrical apparatus according to claim 9 , being any one of a ventilation apparatus, dehumidifier, humidifier, air conditioning unit, hot-water supply machine, fan-filter unit and cooling unit.