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

Patent · Sun Jan 01 00:00:00 EST 1984

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.

• DOE Contract Number: DEN 3-211
• Assignee: Eaton Corporation (Cleveland, OH)
• Patent Number(s): US 4458194
• OSTI ID: 865073
• Country of Publication: United States
• Language: English

Related Subjects

method
apparatus
pulse
width
modulation
control
induction
motor
inverter
connected
source
dc
power
three-phase
micro-processor-based
circuit
controls
techniques
disclosed
edges
carrier
train
equally
modulated
time
proportional
theta
angular
displacement
center
stator
frequency
fixed
reference
waveform
multiple
applied
phase
inputs
respective
shifts
120
degree
switching
commands
electronic
switches
stored
random
access
memory
locations
successively
cyclic
manner
bit
location
controlling
input
preferably
comprises
rechargeable
batteries
disabled
remaining
switch
flyback
dc-dc
converter
recharging
battery
random access
width modulation
access memory
carrier wave
rechargeable batteries
angular displacement
circuit controls
motor stator
electronic switches
dc-dc converter
disclosed method
induction motor
pulse train
phase shift
dc power
pulse width
power source
preferably comprises
phase shifts
phase input
respective phase
source preferably
modulated pulse
fixed reference
electronic switch
cyclic manner
modulation techniques
modulation control
preferably comprise
/318/363/