Protection circuit in inverter for refrigerators
First Claim
1. A refrigerator adapted to be connected to a source of DC voltage, said refrigerator comprising:
- a housing;
a compressor disposed within said housing;
a motor operably connected to said compressor; and
inverter means for driving said motor, said inverter means adapted to be coupled to the DC voltage source and including means for generating a multiple phase AC output from the DC voltage source and means for providing said multiple phase AC output to said motor, said inverter means further including timing means for regulating the frequency of said generating means, said timing means causing said multiple phase AC output to be at a frequency which is proportional to the voltage level of the DC voltage source, said generating means being responsive to said timing means so that changes in the voltage level of the DC voltage source change the frequency of said multiple phase AC output, said inverter means further including means for minimizing the time delay in starting operation of said inverter when DC voltage is supplied.
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Abstract
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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Citations
43 Claims
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1. A refrigerator adapted to be connected to a source of DC voltage, said refrigerator comprising:
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a housing; a compressor disposed within said housing; a motor operably connected to said compressor; and inverter means for driving said motor, said inverter means adapted to be coupled to the DC voltage source and including means for generating a multiple phase AC output from the DC voltage source and means for providing said multiple phase AC output to said motor, said inverter means further including timing means for regulating the frequency of said generating means, said timing means causing said multiple phase AC output to be at a frequency which is proportional to the voltage level of the DC voltage source, said generating means being responsive to said timing means so that changes in the voltage level of the DC voltage source change the frequency of said multiple phase AC output, said inverter means further including means for minimizing the time delay in starting operation of said inverter when DC voltage is supplied. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A refrigerator adapted to be connected either to a first source of DC voltage which provides a first voltage, or to a second source of DC voltage which provides a second voltage, said refrigerator comprising:
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a compressor; a motor operably connected to said compressor, said motor including three windings capable of being arranged in a delta or a wye configuration; and inverter means for driving said motor, said inverter means adapted to be coupled either to the first or second DC voltage source and including means for generating a multiple phase AC output from the coupled DC voltage source and means for regulating said multiple phase AC output to said windings, said inverter means including means for converting said inverter means between first and second arrangements, said converting means includes a power regulating circuit for providing power to said first arrangement of said inverter means when said inverter means is coupled to the first DC voltage source and said motor is arranged in said delta configuration, said power regulating circuit also for providing power to said second arrangement of said inverter means when said inverter means is coupled to the second DC voltage source and said motor is arranged in said wye configuration; said power regulating circuit including first voltage control means for controlling the voltage supplied to said first arrangement, said first voltage control means including first clipping means for limiting the voltage supplied to said inverter means to a first predetermined voltage level and resistance means for limiting the amount of power delivered to said generating means; said power regulating circuit including second storage control means for controlling the voltage supplied to said second arrangement, said second voltage control means being removably connected to said power regulating circuit and including second clipping means for limiting the voltage supplied to said inverter means to a second predetermined voltage level and means for disconnecting said resistance means from said power regulating circuit. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A refrigerator comprising:
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a housing; a compressor disposed within said housing; a motor operably connected to said compressor; a power supply means for providing DC voltage; inverter means for receiving said DC voltage and driving said motor, said inverter means including means for generating a multiple phase AC output from said DC voltage and means for providing said multiple phase AC output to said motor, said inverter means further including timing means for regulating the frequency of said generating means, said timing means causing said multiple phase AC output to be at a frequency which is proportional to the voltage level of said DC voltage, said generating means being responsive to said timing means so that changes in the voltage level of said power supply means change the frequency of said multiple phase AC output; and cut off means for stopping said inverter when said cut off means determines that said DC voltage falls below a predetermined voltage, said cut off means including a Zener diode having a predetermined voltage threshold, a switching means connected to said Zener diode, and a means for de-energizing said multiple phase AC output providing means, said Zener diode being coupled to said power supply means, said power supply means normally providing a DC voltage which exceeds said predetermined voltage threshold of said Zener diode, said switching means being triggered by an absence of voltage apparent at said Zener diode and activating said de-energizing means when said DC voltage falls below said predetermined threshold to thereby turn off said inverter means. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43)
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Specification