Method and apparatus for pulse width modulation control of an AC induction motor

Patent · Sat Dec 31 23:00:00 EST 1983

OSTI ID:865073

Geppert, Steven ^[1]; Slicker, James M ^[2]

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1. Bloomfield Hills, MI
2. Union Lake, MI

An inverter is connected between a source of DC power and a three-phase AC induction motor, and a micro-processor-based circuit controls the inverter using pulse width modulation techniques. In the disclosed method of pulse width modulation, both edges of each pulse of a carrier pulse train are equally modulated by a time proportional to sin .THETA., where .THETA. is the angular displacement of the pulse center at the motor stator frequency from a fixed reference point on the carrier waveform. The carrier waveform frequency is a multiple of the motor stator frequency. The modulated pulse train is then applied to each of the motor phase inputs with respective phase shifts of 120.degree. at the stator frequency. Switching control commands of electronic switches in the inverter are stored in a random access memory (RAM) and the locations of the RAM are successively read out in a cyclic manner, each bit of a given RAM location controlling a respective phase input of the motor. The DC power source preferably comprises rechargeable batteries and all but one of the electronic switches in the inverter can be disabled, the remaining electronic switch being part of a "flyback" DC-DC converter circuit for recharging the battery.

• Assignee: Eaton Corporation (Cleveland, OH)
• Patent Number(s): US 4458194
• OSTI ID: 865073
• Country of Publication: United States
• Language: English

Related Subjects

/318/363/
120
access
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angular
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apparatus
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batteries
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bit
carrier
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center
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circuit controls
commands
comprises
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induction
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modulated
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motor
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pulse width
random
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rechargeable
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stator
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