| 摘要 |
The present invention is an inverter for a portable refrigerator. The inverter includes a square wave generator operable by a DC voltage source. A timer is also included which, in conjunction with the square wave generator, provides a multiple phase waveform for operating a compressor motor. 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 or delta winding configuration. The inverter also includes a protection circuit which protects against locked rotor and overload current conditions, as well as a shut-off circuit to guard against operating at low speeds and completely draining the battery.
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