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Claims  |
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What is claimed:
1. An AC motor drive system for driving an AC motor having a first winding
and a second winding, the first winding having first and second ends and a
first winding impedance, the second winding having first and second ends
and a second winding impedance that is greater than the first impedance,
said drive system comprising:
two-phase power supply means for inverting an inputted DC power supply
voltage into a two-phase AC output voltage, said two-phase power supply
means having a common terminal, a first phase output terminal, and a
second phase output terminal;
said common terminal for connection to the respective first ends of the
first and second windings; and
said first phase terminal and said second phase terminal for connection to
the second ends of said first and second windings, respectively;
whereby said two-phase power supply means converts the inputted power
supply voltage to a two-phase voltage provided on said first, second and
common terminals to drive the motor.
2. An AC motor drive system for driving an AC motor having a first winding
and a second winding, the first winding having first and second ends and a
first winding impedance, the second winding having first and second ends
and a second winding impedance that is greater than the first impedance,
said drive system comprising:
two-phase power supply means for converting an inputted power supply
voltage into a two-phase AC output voltage, said two-phase power supply
means having a common terminal, a first phase output terminal, and a
second phase output terminal;
said common terminal for connection to the respective first ends of the
first and second windings; and
said first phase terminal and said second phase terminal for connection to
the second ends of said first and second windings, respectively;
wherein said two-phase power supply means generates the two-phase AC output
voltage having a first phase voltage between said first phase output and
common terminals, a second phase voltage between said second phase output
and common terminals, and a preselected phase angle relationship between
the first and second phase voltages;
whereby said two-phase power supply means converts the inputted power
supply voltage to a two-phase voltage provided on said first, second and
common terminals to drive the motor.
3. An AC motor drive system for driving an AC motor having a first winding
and a second winding, the first winding having first and second ends and a
first winding impedance, the second winding having first and second ends
and a second winding impedance that is greater than the first impedance,
said drive system comprising:
two-phase power supply means for converting an inputted power supply
voltage into a two-phase AC output voltage, said two-phase power supply
means having a common terminal, a first phase output terminal, and a
second phase output terminal;
said common terminal for connection to the respective first ends of the
first and second windings; and
said first phase terminal and said second phase terminal for connection to
the second ends of said first and second windings, respectively;
wherein said two-phase power supply means generates the two-phase AC output
voltage having a first phase voltage between said first phase output and
common terminals, a second phase voltage between said second phase output
and common terminals, a ratio of respective magnitudes of the second phase
voltage to the first phase voltage having a preselected value greater than
1;
whereby said two-phase power supply means converts the inputted power
supply voltage to a two-phase voltage provided on said first, second and
common terminals to drive the motor.
4. An AC motor drive system for driving an AC motor having a first winding
and a second winding, the first winding having first and second ends and a
first winding impedance, the second winding having first and second ends
and a second winding impedance that is greater than the first impedance,
said drive system comprising:
two-phase power supply means for converting an inputted power supply
voltage into a two-phase AC output voltage, said two-phase power supply
means having a common terminal, a first phase output terminal, and a
second phase output terminal;
said common terminal for connection to the respective first ends of the
first and second windings; and
said first phase terminal and said second phase terminal for connection to
the second ends of said first and second windings, respectively;
wherein said two-phase power supply means is responsive to an externally
applied speed control signal to vary the frequency of the two-phase AC
output voltage to thereby vary a rotational speed of the AC motor in
accordance with the speed control signal;
whereby said two-phase power supply means converts the inputted power
supply voltage to a two-phase voltage provided on said first, second and
common terminals to drive the motor.
5. The AC motor drive system of claim 4 wherein said two-phase power supply
means generates the two-phase AC output voltage having a first phase
voltage between said first phase output and common terminals and a second
phase voltage between said second phase output and common terminals; and
wherein said two-phase power supply means is further responsive to the
speed control signal to vary respective magnitudes of the first and second
phase voltages to maintain substantially constant ratios of voltage to
frequency for the respective first and second windings of the AC motor.
6. The AC motor drive system of claim 5 wherein said two-phase power supply
means maintains a preselected ratio of the respective magnitudes of the
second phase voltage to the first phase voltage, the preselected ratio
being greater than 1.
7. An AC motor drive system, for connection to a single-phase power supply
having a line conductor and a neutral conductor, for driving an AC motor
having a first winding and a second winding, the first winding having
first and second ends and a first winding impedance, the second winding
having first and second ends and a second winding impedance that is
greater than the first impedance, said drive system comprising:
two-phase power supply means, including a line terminal for coupling to the
line conductor of the single-phase power supply, for rectifying the
single-phase power supply and for inverting the rectified single-phase
power supply into a two-phase output voltage, said two-phase power supply
means having a first phase output terminal and a second phase output
terminal;
a neutral terminal for connection to the neutral conductor of the
single-phase power supply and for connection to the respective first ends
of the first and second windings; and
said first and second phase terminals for connection to the second ends of
said first and second windings, respectively;
whereby said two-phase power supply means converts power received from the
single-phase power supply to a two-phase voltage to drive the motor.
8. An AC motor drive system, for connection to a single-phase power supply
having a line conductor and a neutral conductor, for driving an AC motor
having a first winding and a second winding, the first winding having
first and second ends and a first winding impedance, the second winding
having first and second ends and a second winding impedance that is
greater than the first impedance, said drive system comprising:
two-phase power supply means, including a line terminal for coupling to the
line conductor of the single-phase power supply, for converting the
single-phase power supply into a two-phase output voltage, said two-phase
power supply means having a first phase output terminal and a second phase
output terminal;
a neutral terminal for connection to the neutral conductor of the
single-phase power supply and for connection to the respective first ends
of the first and second windings; and
said first and second phase terminals for connection to the second ends of
said first and second windings, respectively;
wherein said two-phase power supply means generates the two-phase AC output
voltage having a first phase voltage between said first phase output and
neutral terminals, a second phase voltage between said second phase output
and neutral terminals, and a preselected phase angle relationship between
the first and second phase voltages;
whereby said two-phase power supply means converts power received from the
single-phase power supply to a two-phase voltage to drive the motor.
9. An AC motor drive system, for connection to a single-phase power supply
having a line conductor and a neutral conductor, for driving an AC motor
having a first winding and a second winding, the first winding having
first and second ends and a first winding impedance, the second winding
having first and second ends and a second winding impedance that is
greater than the first impedance, said drive system comprising:
two-phase power supply means, including a line terminal for coupling to the
line conductor of the single-phase power supply, for converting the
single-phase power supply into a two-phase output voltage, said two-phase
power supply means having a first phase output terminal and a second phase
output terminal;
a neutral terminal for connection to the neutral conductor of the
single-phase power supply and for connection to the respective first ends
of the first and second windings; and
said first and second phase terminals for connection to the second ends of
said first and second windings, respectively;
wherein said two-phase power supply means generates the two-phase AC output
voltage having a first phase voltage between said first phase output and
neutral terminals, a second phase voltage between said second phase output
and neutral terminals, a ratio of respective magnitudes of the second
phase voltage to the first phase voltage having a preselected value
greater than 1;
whereby said two-phase power supply means converts power received from the
single-phase power supply to a two-phase voltage to drive the motor.
10. An AC motor drive system, for connection to a single-phase power supply
having a line conductor and a neutral conductor, for driving an AC motor
having a first winding and a second winding, the first winding having
first and second ends and a first winding impedance, the second winding
having first and second ends and a second winding impedance that is
greater than the first impedance, said drive system comprising:
two-phase power supply means, including a line terminal for coupling to the
line conductor of the single-phase power supply, for converting the
single-phase power supply into a two-phase output voltage, said two-phase
power supply means having a first phase output terminal and a second phase
output terminal;
a neutral terminal for connection to the neutral conductor of the
single-phase power supply and for connection to the respective first ends
of the first and second windings; and
said first and second phase terminals for connection to the second ends of
said first and second windings, respectively;
wherein said two-phase power supply means is responsive to an externally
applied speed control signal to vary the frequency of the two-phase AC
output voltage to thereby vary a rotational speed of the AC motor in
accordance with the speed control signal;
whereby said two-phase power supply means converts power received from the
single-phase power supply to a two-phase voltage to drive the motor.
11. The AC motor drive system of claim 10 wherein said two-phase power
supply means generates the two-phase AC output voltage having a first
phase voltage between said first phase output and neutral terminals and a
second phase voltage between said second phase output and neutral
terminals; and
wherein said two-phase power supply means is further responsive to the
speed control signal to vary respective magnitudes of the first and second
phase voltages to maintain substantially constant ratios of voltage to
frequency for the respective first and second windings of the AC motor.
12. The AC motor drive system of claim 11 wherein said two-phase power
supply means maintains a preselected ratio of the respective magnitudes of
the second phase voltage to the first phase voltage, the preselected ratio
being greater than 1.
13. An AC motor drive system, comprising:
two-phase power supply means for inverting an inputted DC power supply
voltage into a two-phase AC output voltage, said two-phase power supply
means having a common terminal, a first phase output terminal, and a
second phase output terminal;
an AC motor having a first winding and a second winding;
said first winding having first and second ends and a first winding
impedance;
said second winding having first and second ends and a second wining
impedance that is greater than said first impedance;
the respective first ends of said first and second windings being connected
to the common terminal of said two-phase power supply means; and
the second ends of said first and second windings being respectively
connected to said first phase terminal and said second phase terminal of
said two-phase power supply means;
whereby said two-phase power supply means converts the inputted power
supply voltage to a two-phase voltage provided on said first, second and
common terminals to drive said motor.
14. An AC motor drive system, comprising:
two-phase power supply means for converting an inputted power supply
voltage into a two-phase AC output voltage, said two-phase power supply
means having a common terminal, a first phase output terminal, and a
second phase output terminal;
an AC motor having a first winding and a second winding;
said first winding having first and second ends and a first winding
impedance;
said second winding having first and second ends and a second winding
impedance that is greater than said first impedance;
the respective first ends of said first and second windings being connected
to the common terminal of said two-phase power supply means; and
the second ends of said first and second windings being respectively
connected to said first phase terminal and said second phase terminal of
said two-phase power supply means;
wherein said two-phase power supply means comprises a pulse width modulated
(PWM) inverter system;
whereby said two-phase power supply means converts the inputted power
supply voltage to a two-phase voltage provided on said first, second and
common terminals to drive said motor.
15. The AC motor drive system of claim 14, wherein the inputted power
supply is an AC power supply;
said drive system including means for rectifying the inputted AC power
supply to provide a DC supply voltage; and
said pulse width modulated inverter system comprising
a three-phase inverter circuit including input terminals coupled to receive
the DC voltage and three output terminals respectively corresponding to
said common, first phase and second phase terminals,
switching means, included in said three-phase inverter circuit, for
inverting the DC voltage into the two-phase output voltage, and
voltage control means for generating switching control signals for
controlling the operation of said switching means such that a first phase
of said two-phase output voltage is generated between said first phase and
common terminals and a second phase of said two-phase output voltage is
generated between said second phase and common terminals.
16. The AC motor drive system of claim 15, wherein said three-phase
inverter circuit includes first, second and third inverter bridge legs
connected in parallel;
said switching means comprising a first power switching device and a second
power switching device connected in series in each of said first, second
and third bridge legs, said three output terminals respectively disposed
between the first and second series connected power switching devices of
said first, second and third bridge legs.
17. The AC motor drive system of claim 16, wherein said voltage control
means comprises:
oscillator means for generating a pulse signal having a pulse signal
frequency representative of a desired operating speed of said motor;
means, coupled to said oscillator means, for generating a memory address
signal in response to the pulse signal;
memory means, coupled to said address signal generating means, for
providing a digital data signal in response to each address signal;
waveform signal generating means, responsive to the digital data signals,
for generating a first analog sinusoidal waveform signal and a second
analog sinusoidal waveform signal, said first and second sinusoidal
waveform signals each having a frequency determined by the pulse signal
frequency;
means for inverting the first sinusoidal waveform signal to generate a
third sinusoidal waveform signal;
means for generating a fixed frequency comparison signal;
comparator means, coupled to receive the fixed frequency comparison signal
and the respective first, second and third sinusoidal waveform signals,
for providing first second, and third sinusoidally weighted pulse width
modulated PWM) switching signals; and
output means for providing said first, second and third PWM signals and
respective logical complements thereof as said switching control signals
and for applying said first, second and third PWM signals and their
logical complements to control the operation of said first and second
power switching devices of said first, second and third inverter legs,
respectively.
18. The AC motor drive system of claim 17, wherein said voltage control
means is responsive to an externally generated speed control signal,
representative of the desired motor operating speed, to control the
operating speed of said motor;
said oscillator means generating the pulse signal with the pulse signal
frequency determined by the speed control signal; and
said waveform signal generating means generating the first and second
analog sinusoidal waveform signals each with an amplitude determined by
the speed control signal such that each phase of said two-phase output
voltage has a substantially constant predetermined volts/hertz ratio.
19. The AC motor drive system of claim 18, wherein said waveform signal
generating means is a multiplying dual digital-to-analog converter; and
wherein said comparison signal generating means is a triangular wave
generator.
20. The AC motor drive system of claim 16, wherein said voltage control
means comprises:
oscillator means for generating a pulse signal having a pulse signal
frequency representative of a desired operating speed of said motor;
means, coupled to the oscillator means, for generating an address signal in
response to the pulse signal;
memory means, coupled to said address generating means, for generating a
digital data signal in response to each address signal;
waveform signal generating means, responsive to the digital data signals,
for generating a first, a second and a third sinusoidal waveform signal,
the first, second and third sinusoidal waveform signals each having a
frequency determined by the pulse signal frequency;
means for generating a fixed frequency comparison signal;
comparator means, coupled to receive the fixed frequency comparison signal
and the respective first, second and third sinusoidal waveform signals,
for providing first, second, and third sinusoidally weighted pulse width
modulated (PWM) switching signals; and
output means for providing said first, second and third PWM signals and
respective logical complements thereof as said switching control signals
and for applying said first, second and third PWM signals and their
logical complements to control the operation of said first and second
power switching devices of said first, second and third inverter legs,
respectively;
21. The AC motor drive system of claim 20, wherein said voltage control
means is responsive to an externally generated speed control signal,
representative of the desired motor operating speed, to control the
operating speed of said motor;
said oscillator means generating the pulse signal with the pulse signal
frequency determined by the speed control signal; and
said waveform signal generating means generating the first, second and
third analog sinusoidal waveform signals each with an amplitude determined
by the speed control signal such that said two-phase output voltage has a
substantially constant predetermined volts/hertz ratio.
22. The AC motor drive system of claim 21, wherein said waveform signal
generating means is a multiplying digital-to-analog converter; and
wherein said comparison signal generating means is a triangular wave
generator.
23. The AC motor drive system of claim 17 or 20, wherein said output means
further includes underlap means for providing said first, second and third
PWM signals and their respective logical complements such that each PWM
signal and its logical complement cannot cause the first and second power
switching devices to which they are respectively applied to turn on at the
same time.
24. An AC motor drive system for connection to a single-phase AC power
supply having a line conductor and a neutral conductor, said drive system
comprising:
two-phase power supply means, including a line terminal for coupling to the
line conductor of the single-phase power supply, for rectifying the
single-phase power supply and for inverting the rectified single-phase
power supply into a two-phase output voltage, said two-phase power supply
means having a first phase output terminal and a second phase output
terminal;
a neutral terminal for connection to the neutral conductor of the
single-phase power supply;
an AC motor having a first winding and a second winding;
said first winding having first and second ends and a first winding
impedance;
said second winding having first and second ends and a second winding
impedance that is greater than said first impedance;
the respective first ends of said first and second windings being connected
to said neutral terminal; and
the second ends of said first and second windings being respectively
coupled to said first and second phase terminals of said two-phase power
supply means.
25. An AC motor drive system, for connection to a single-phase AC power
supply having a line conductor and a neutral conductor, said drive system
comprising:
two-phase power supply means, including a line terminal for coupling to the
line conductor of the single-phase power supply, for converting the
single-phase power supply into a two-phase output voltage, said two-phase
power supply means having a first phase output terminal and a second phase
output terminal, said two-phase power supply means including
means for rectifying the single-phase power supply to provide a DC supply
voltage on positive and negative polarity terminals, and
pulse width modulated inverter means, coupled to the positive and negative
polarity terminals, for inverting the DC supply voltage to provide the
two-phase output voltage;
a neutral terminal for connection to the neutral conductor of the
single-phase power supply;
an AC motor having a first winding and a second winding;
said first winding having first and second ends and a first winding
impedance;
said second winding having first and second ends and a second winding
impedance that is greater than said first impedance;
the respective first ends of said first and second windings being connected
to said neutral terminal; and
the second ends of said first and second windings being respectively
coupled to said first and second phase terminals of said two-phase power
supply means.
26. The AC motor drive system of claim 25, said pulse width modulated
inverter means including:
a first half bridge circuit including
a first power switching device and a second power switching device coupled
in series between the positive and negative polarity terminals, and
a first tap node between the series connected first and second power
switching devices, said first tap node being coupled to said first phase
output terminal;
a second half bridge circuit including
a third power switching device and a fourth power switching device coupled
in series between the positive and negative polarity terminals, and
a second tap node between the series connected third and fourth power
switching devices, said second tap node being connected to the second
phase terminal; and
voltage control means for generating switching control signals for
controlling the operation of said first, second, third and fourth power
switching devices to provide the two-phase output voltage on said first
and second phase terminals.
27. The AC motor drive system of claim 26, wherein the voltage control
means includes:
means for generating a fixed frequency comparison signal;
waveform signal generating means for generating a first sinusoidal waveform
signal and a second sinusoidal waveform signal to have a predetermined
phase angle difference therebetween and a common frequency that
corresponds to a desired operating speed of said motor;
first comparator means, coupled to receive said first sinusoidal waveform
signal and the fixed frequency signal, for providing a first sinusoidally
weighted pulse width modulated (PWM) switching signal;
second comparator means, coupled to receive the second sinusoidal waveform
signal and the fixed frequency signal, for providing a second sinusoidally
weighted pulse width modulated (PWM) switching signal; and
output means for providing said first and second PWM signals and respective
logical complements thereof as said switching control signals, for
applying said first PWM signal and its logical complement to respectively
control said first and second power switching devices of said first half
bridge, and for applying said second PWM signal and its logical complement
to respectively control said third and fourth power switching devices of
said second half bridge.
28. The AC motor drive system of claim 27, wherein said voltage control
means is responsive to an externally generated speed control signal,
representative of the desired motor operating speed, to control the
operating speed of said motor;
said waveform signal generating means generating said first and second
sinusoidal waveform signals with the common frequency determined by the
speed control signal;
said voltage control means further comprising:
first filter means, coupled between said waveform signal generating means
and said first comparator means, for varying an amplitude of the first
sinusoidal waveform signal in accordance with the common frequency thereof
in a manner effective to maintain a substantially constant ratio between
the amplitude and the common frequency of the first sinusoidal waveform
signal applied to said first comparator means; and
second filter means, coupled between said waveform signal generating means
and said second comparator means, for varying an amplitude of the second
sinusoidal waveform signal in accordance with the common frequency thereof
in a manner effective to maintain a substantially constant ratio between
the amplitude and the common frequency of the second sinusoidal waveform
signal applied to said second comparator means.
29. The AC motor drive system of claim 28 wherein said first filter means
includes means for adjusting a filter setpoint so that by adjusting the
filter set point the amplitude of the first sinusoidal waveform signal can
be attenuated by a greater amount than an amount by which said second
filter means attenuates the second sinusoidal waveform signal.
30. The AC motor drive system of claim 28 wherein the predetermined phase
angle between the first and second sinusoidal waveform signals is
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