| 摘要 |
<p>The present invention is an inverter (12) for a portable refrigerator (8). The inverter includes a square wave generator (30) operable by a DC voltage source (10). A timer (28) is also included which, in conjunction with the square wave generator, provides a multiple phase waveform for operating a compressor motor (14). For conventional three winding compressor motors, the inverter provides a six-step waveform for operation of the portable refrigerator. The inverter can also drive the motor using either a first or second DC voltage level, by minor changes in the inverter and using either a wye (22) or delta (24) winding configuration. The inverter also includes a protection circuit (74) which protects against locked rotor and overload current, as well as a shut-off circuit (50) to guard against operating at low speeds and completely draining the battery. <IMAGE></p> |
