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Claims  |
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What is claimed is:
1. A protection apparatus of a brushless motor comprising:
a brushless motor;
commutation signal detecting means for detecting a position of a movable
member of said brushless motor;
speed detecting means for detecting a rotation speed of the movable member
of said brushless motor, involving a rotation direction thereof, in
response to the detection signal outputted from said commutation signal
detecting means;
a drive circuit for producing a commutation signal used to drive the
movable member of said brushless motor in response to the detection signal
outputted from said commutation signal detecting means and for driving
said brushless motor based upon said commutation signal;
output voltage instructing means for supplying to said drive circuit, an
output voltage instruction signal for instructing an output voltage of
said drive circuit, which constitutes a drive voltage when said brushless
motor is driven;
voltage limit level setting means for setting an upper limit value of the
output voltage of said drive circuit; and
voltage limiter means for limiting the output signal of said output voltage
instructing means based on the setting value of said voltage limit level
setting means to thereby limit an upper limit value of the output voltage
of said drive circuit; wherein:
the setting value of said voltage limit level setting means is set in
accordance with the detecting signal outputted from said speed detecting
means in such a manner that the higher the rotation speed of the movable
member of said brushless motor, said setting value becomes a large value;
the lower the rotation speed of the movable member of said brushless
motor, said setting value becomes a small value; and when the rotation
speed becomes near zero and the rotation direction is reversed, said
setting value becomes a preset constant value.
2. A protection apparatus of a brushless motor as claimed in claim 1,
wherein:
the setting value of said voltage limit level setting means is corrected in
such a manner that a fluctuation and a variation contained in the induced
voltage internally produced from said brushless motor are grasped based
upon the drive current of the brushless motor in order to compensate for
the fluctuation and the variation contained in the induced voltage of said
brushless motor.
3. A protection apparatus of a brushless motor comprising:
a DC (direct current) main power supply;
a brushless motor;
commutation signal detecting means for detecting a position of a movable
member of said brushless motor;
speed detecting means for detecting a rotation speed of the movable member
of said brushless motor, involving a rotation direction thereof, in
response to the detection signal outputted from said commutation signal
detecting means;
a drive circuit for producing a commutation signal used to drive the
movable member of said brushless motor in response to the detection signal
outputted from said commutation signal detecting means and for driving
said brushless motor based upon said commutation signal, said drive
circuit outputting the output voltage of said DC main power supply in a
ratio responding to an output voltage instruction signal as a drive
voltage used when said brushless motor is driven;
output voltage instructing means for supplying said output voltage
instruction signal to said drive circuit;
voltage limit level setting means for setting an upper limit value of the
output voltage of said drive circuit, the setting value of said voltage
limit level setting means being set in accordance with the detecting
signal outputted from said speed detecting means in such a manner that the
higher the rotation speed of the movable member of said brushless motor,
said setting value becomes a large value; the lower the rotation speed of
the movable member of said brushless motor, said setting value becomes a
small value; and when the rotation speed becomes near zero and the
rotation direction is reversed, said setting value becomes a preset
constant value; voltage limiter means for limiting the output signal of
said output voltage instructing means based on the setting value of said
voltage limit level setting means to thereby supply the limited output
signal to said drive circuit and limit an upper limit value of the output
voltage of said drive circuit;
voltage variation detecting means for detecting a variation contained in
the output voltage of said DC main power supply in a direct manner, or
based upon any one of an output current of said DC main power supply and a
drive current of said brushless motor; and
voltage correcting means for applying said output voltage instruction
signal to said drive circuit by conversely changing the output signal of
said voltage limiter means in order to compensate for the variation
contained in the output voltage of said DC main power supply based upon
the detection output from said voltage variation detecting means.
4. A protection apparatus of a brushless motor comprising:
a brushless motor;
commutation signal detecting means for detecting a position of a movable
member of said brushless motor;
speed detecting means for detecting a rotation speed of the movable member
of said brushless motor, involving a rotation direction thereof, in
response to the detection signal outputted from said commutation signal
detecting means;
a drive circuit for producing a commutation signal used to drive the
movable member of said brushless motor in response to the detection signal
outputted from said commutation signal detecting means and for driving
said brushless motor based upon said commutation signal;
output voltage instructing means for supplying to said drive circuit, an
output voltage instruction signal for instructing an output voltage of
said drive circuit, which constitutes a drive voltage when said brushless
motor is driven;
voltage limit level setting means for setting an upper limit value of the
output voltage of said drive circuit; and
voltage limiter means for limiting the output signal of said output voltage
instructing means based on the setting value of said voltage limit level
setting means to thereby limit an upper limit value of the output voltage
of said drive circuit;
normal rotation limiter means for detecting as to whether or not the
rotation speed of said brushless motor reaches a preset maximum limit
level based upon the detection signal of said speed detecting means, and
for outputting a first power supply interrupting signal when said rotation
speed reaches said preset maximum limit level; and
reverse rotation limiter means for detecting as to whether or not a reverse
rotation speed of said brushless motor reaches a preset reverse rotation
limit level based upon the detection signal of said speed detecting means,
and for outputting a second power supply interrupting signal when said
reverse rotation speed reaches said preset reverse rotation limit level;
wherein:
the setting value of said voltage limit level setting means is set in
accordance with the detecting signal outputted from said speed detecting
means in such a manner that the higher the rotation speed of the movable
member of said brushless motor, said setting value becomes a large value;
the lower the rotation speed of the movable member of said brushless
motor, said setting value becomes a small value; and when the rotation
speed becomes near zero and the rotation direction is reversed, said
setting value becomes a preset constant value; and also when said first
power supply interrupting signal outputted from said normal rotation
limiter means is produced, or said second power supply interrupting signal
outputted from said reverse rotation limiter means is produced, said drive
circuit is electrically opened from said brushless motor.
5. A protection apparatus for a brushless motor as claimed in claim 4
wherein:
said normal rotation limiter means includes hysteresis means operable in
such a manner that the first power supply interrupting signal is outputted
when the rotation speed of the brushless motor reaches the preset maximum
limit level; outputting of said first power supply interrupting signal is
maintained during a time period such that after said first power supply
interrupting signal is outputted, the rotation speed of said brushless
motor reaches a power supply interrupting signal release level equal to a
rotation speed slightly lower than said maximum limit level; outputting of
said first power supply interrupting signal is released when the rotation
speed of said brushless motor reaches said power supply interrupting
signal release level; and thereafter said first power supply interrupting
signal is not outputted until the rotation speed of said brushless motor
reaches said maximum limit level.
6. A protection apparatus of a brushless motor comprising:
a DC (direct current) main power supply;
a brushless motor;
commutation signal detecting means for detecting a position of a movable
member of said brushless motor;
speed detecting means for detecting a rotation speed of the movable member
of said brushless motor, involving a rotation direction thereof, in
response to the detection signal outputted from said commutation signal
detecting means;
a drive circuit for producing a commutation signal used to drive the
movable member of said brushless motor in response to the detection signal
outputted from said commutation signal detecting means and for driving
said brushless motor based upon said commutation signal, said drive
circuit outputting the output voltage of said DC main power supply in a
ratio responding to an output voltage instruction signal as a drive
voltage used when said brushless motor is driven;
output voltage instructing means for supplying said output voltage
instruction signal to said drive circuit;
voltage limit level setting means for setting an upper limit value of the
output voltage of said drive circuit, the setting value of said voltage
limit level setting means being set in accordance with the detecting
signal outputted from said speed detecting means in such a manner that the
higher the rotation speed of the movable member of said brushless motor,
said setting value becomes a large value; the lower the rotation speed of
the movable member of said brushless motor, said setting value becomes a
small value; and when the rotation speed becomes near zero and the
rotation direction is reversed, said setting value becomes a preset
constant value; voltage limiter means for limiting the output signal of
said output voltage instructing means based on the setting value of said
voltage limit level setting means to thereby supply the limited output
signal to said drive circuit and limit an upper limit value of the output
voltage of said drive circuit;
normal rotation limiter means for detecting as to whether or not the
rotation speed of said brushless motor reaches a preset maximum limit
level based upon the detection signal of said speed detecting means, and
for outputting a first power supply interrupting signal when said rotation
speed reaches said preset maximum limit level;
reverse rotation limiter means for detecting as to whether or not a reverse
rotation speed of said brushless motor reaches a preset reverse rotation
limit level based upon the detection signal of said speed detecting means,
and for outputting a second power supply interrupting signal when said
reverse rotation speed reaches said preset reverse rotation limit level;
in which when said first power supply interrupting signal outputted from
said normal rotation limiter means or said second power supply
interrupting signal outputted from said reverse rotation limiter means is
produced, said drive circuit is electrically opened from said brushless
motor;
voltage variation detecting means for detecting a variation contained in
the output voltage of said DC main power supply in a direct manner, or
based upon any one of an output current of said DC main power supply and a
drive current of said brushless motor; and
voltage correcting means for applying said output voltage instruction
signal to said drive circuit by conversely changing the output signal of
said voltage limiter means in order to compensate for the variation
contained in the output voltage of said DC main power supply based upon
the detection output from said voltage variation detecting means.
7. A protection apparatus of a brushless motor comprising:
a brushless motor;
commutation signal detecting means for detecting a position of a movable
member of said brushless motor;
speed detecting means for detecting a rotation speed of the movable member
of said brushless motor, involving a rotation direction thereof, in
response to the detection signal outputted from said commutation signal
detecting means;
a drive circuit for producing a commutation signal used to drive the
movable member of said brushless motor in response to the detection signal
outputted from said commutation signal detecting means and for driving
said brushless motor based upon said commutation signal;
output voltage instructing means for supplying to said drive circuit, an
output voltage instruction signal for instructing an output voltage of
said drive circuit, which constitutes a drive voltage when said brushless
motor is driven;
voltage limit level setting means for setting an upper limit value of the
output voltage of said drive circuit;
voltage limiter means for limiting the output signal of said output voltage
instructing means based on the setting value of said voltage limit level
setting means to thereby limit an upper limit value of the output voltage
of said drive circuit;
normal rotation limiter means for detecting as to whether or not the
rotation speed of said brushless motor reaches a preset maximum limit
level based upon the detection signal of said speed detecting means, and
for outputting a first power supply interrupting signal when said rotation
speed reaches said preset maximum limit level;
reverse rotation limiter means for detecting as to whether or not a reverse
rotation speed of said brushless motor reaches a preset reverse rotation
limit level based upon the detection signal of said speed detecting means,
and for outputting a second power supply interrupting signal when said
reverse rotation speed reaches said preset reverse rotation limit level;
low speed failure detecting means for detecting as to whether or not the
rotation speed of said brushless motor becomes below a preset low speed
failure sensing level, and for outputting a low speed failure signal when
said rotation speed becomes below said preset low speed failure sensing
level; and low speed overload detecting means containing said low speed
failure sensing means, for latch-processing a third power supply
interrupting signal to thereby output the latch-processed third power
supply interrupting signal in the case that such a condition that said low
speed failure signal is outputted from said low speed failure sensing
means and also said second power supply interrupting signal is not
outputted from said reverse rotation limiter means is continued for a
predetermined time period; wherein:
the setting value of said voltage limit level setting means is set in
accordance with the detecting signal outputted from said speed detecting
means in such a manner that the higher the rotation speed of the movable
member of said brushless motor, said setting value becomes a large value;
the lower the rotation speed of the movable member of said brushless
motor, said setting value becomes a small value; and when the rotation
speed becomes near zero and the rotation direction is reversed, said
setting value becomes a preset constant value; and also when said first
power supply interrupting signal outputted from said normal rotation
limiter means, said second power supply interrupting signal outputted from
said reverse rotation limiter means, or said third power supply
interrupting signal outputted from said low speed overload detecting means
is produced, said drive circuit is electrically opened from said brushless
motor.
8. A protection apparatus of a brushless motor comprising:
a DC (direct current) main power supply;
a brushless motor;
commutation signal detecting means for detecting a position of a movable
member of said brushless motor;
speed detecting means for detecting a rotation speed of the movable member
of said brushless motor, involving a rotation direction thereof, in
response to the detection signal outputted from said commutation signal
detecting means;
a drive circuit for producing a commutation signal used to drive the
movable member of said brushless motor in response to the detection signal
outputted from said commutation signal detecting means and for driving
said brushless motor based upon said commutation signal, said drive
circuit outputting the output voltage of said DC main power supply in a
ratio responding to an output voltage instruction signal as a drive
voltage used when said brushless motor is driven;
output voltage instructing means for supplying said output voltage
instruction signal to said drive circuit;
voltage limit level setting means for setting an upper limit value of the
output voltage of said drive circuit, the setting value of said voltage
limit level setting means being set in accordance with the detecting
signal outputted from said speed detecting means in such a manner that the
higher the rotation speed of the movable member of said brushless motor,
said setting value becomes a large value; the lower the rotation speed of
the movable member of said brushless motor, said setting value becomes a
small value; and when the rotation speed becomes near zero and the
rotation direction is reversed, said setting value becomes a preset
constant value; voltage limiter means for limiting the output signal of
said output voltage instructing means based on the setting value of said
voltage limit level setting means to thereby supply the limited output
signal to said drive circuit and limit an upper limit value of the output
voltage of said drive circuit;
normal rotation limiter means for detecting as to whether or not the
rotation speed of said brushless motor reaches a preset maximum limit
level based upon the detection signal of said speed detecting means, and
for outputting a first power supply interrupting signal when said rotation
speed reaches said preset maximum limit level;
reverse rotation limiter means for detecting as to whether or not a reverse
rotation speed of said brushless motor reaches a preset reverse rotation
limit level based upon the detecting signal of said speed detecting means,
and for outputting a second power supply interrupting signal when said
reverse rotation speed reaches said preset reverse rotation limit level;
low speed failure detecting means for detecting as to whether or not the
rotation speed of said brushless motor becomes below a preset low speed
failure sensing level, and for outputting a low speed failure signal when
said rotation speed becomes below said preset low speed failure sensing
level;
low speed overload detecting means containing said low speed failure
sensing means, for latch-processing a third power supply interrupting
signal to thereby output the latch-processed third power supply
interrupting signal in the case that such a condition that said low speed
failure signal is outputted from said low speed failure sensing means and
also said second power supply interrupting signal is not outputted from
said reverse rotation limiter means is continued for a predetermined time
period;
voltage variation detecting means for detecting a variation contained in
the output voltage of said DC main power supply in a direct manner, or
based upon any one of an output current of said DC main power supply and a
drive current of said brushless motor, in which when said first power
supply interrupting signal outputted from said normal rotation limiter
means, said second power supply interrupting signal outputted from said
reverse rotation limiter means, or the third power supply interrupting
signal outputted from said low speed overload detecting means is produced,
said drive circuit is electrically opened from said brushless motor; and
voltage correcting means for applying said output voltage instruction
signal to said drive circuit by conversely changing the output signal of
said voltage limiter means in order to compensate for the variation
contained in the output voltage of said DC main power supply based upon
the detection output from said voltage variation detecting means.
9. A protection apparatus of a brushless motor comprising:
a brushless motor;
commutation signal detecting means for detecting a position of a movable
member of said brushless motor;
speed detecting means for detecting a rotation speed of the movable member
of said brushless motor, involving a rotation direction thereof, in
response to the detection signal outputted from said commutation signal
detecting means;
a drive circuit for producing a commutation signal used to drive the
movable member of said brushless motor in response to the detection signal
outputted from said commutation signal detecting means and for driving
said brushless motor based upon said commutation signal;
output voltage instructing means for supplying to said drive circuit, an
output voltage instruction signal for instructing an output voltage of
said drive circuit, which constitutes a drive voltage when said brushless
motor is driven;
voltage limit level setting means for setting an upper limit value of the
output voltage of said drive circuit;
voltage lower limit level setting means for setting a lower limit value of
the output voltage of said drive circuit;
voltage limiter means for limiting the output signal of said output voltage
instructing means based on the setting value of said voltage limit level
setting means to thereby limit an upper limit value of the output voltage
of said drive circuit, and also for limiting the output signal of said
output voltage instructing means based upon the setting value of said
voltage lower limit level setting means to thereby limit the lower limit
value of the output voltage of said drive circuit; and
reverse rotation limiter means for detecting as to whether or not a reverse
rotation speed of said brushless motor reaches a preset reverse rotation
limit level based upon the detection signal of said speed detecting means,
and for outputting a second power supply interrupting signal when said
reverse rotation speed reaches said preset reverse rotation limit level;
wherein,
when said second power supply interrupting signal outputted from said
reverse rotation limiter means is produced, the connection between said
drive circuit and said brushless motor is electrically opened, and also
the setting value of said voltage limit level setting means is set in
accordance with the detecting signal outputted from said speed detecting
means in such a manner that the higher the rotation speed of the movable
member of said brushless motor, said setting value becomes a large value;
the lower the rotation speed of the movable member of said brushless
motor, said setting value becomes a small value; and when the rotation
speed becomes near zero and the rotation direction is reversed, said
setting value becomes a preset constant value and further the setting
value of said voltage lower limit level setting means is set in response
to the output signal of said speed detecting means in such a manner that
said setting value is such a value lower than the setting value of said
voltage limit level setting means, and also such a value higher than a
value corresponding to an induced voltage internally produced from said
brushless motor.
10. A protection apparatus of a brushless motor as claimed in claim 9,
wherein:
either one or both the setting value of said voltage limit level setting
means and said setting value of said voltage lower limit level setting
means is corrected in such a manner that a fluctuation and a variation
contained in the induced voltage internally produced from said brushless
motor are grasped based upon the drive current of the brushless motor in
order to compensate for the fluctuation and the variation contained in the
induced voltage of said brushless motor.
11. A protection apparatus of a brushless motor comprising:
a DC (direct current) main power supply;
a brushless motor;
commutation signal detecting means for detecting a rotation speed of the
movable member of said brushless motor, involving a rotation direction
thereof, in response to the detection signal outputted from said
commutation signal detecting means;
a drive circuit for producing a commutation signal used to drive the
movable member of said brushless motor in response to the detection signal
outputted from said commutation signal detectiong means and for driving
said brushless motor based upon said commutation signal, said drive
circuit outputting the output voltage of said DC main power supply in a
ratio responding to an output voltage instruction signal as a drive
voltage used when said brushless motor is driven;
output voltage instructing means for supplying said output voltage
instruction signal to said drive circuit;
voltage linit level setting means for setting an upper limit value of the
output voltage of said drive circuit, the setting value of said voltage
limit level setting means being set inaccordance with the detecting signal
outputted from said speed detecting means in such a manner that the higher
the rotation speed of the movable member of said brushless motor, said
setting value becomes a large value; the lower the rotation speed of the
movable member of said brushless motor, said setting value becomes a small
value; and when the rotation speed becomes near zero and the rotation
direction is reversed, said setting value becomes a preset value;
voltage lower limit level setting means for setting a lower limit value of
the output voltage of said drive circuit, the setting value of said
voltage lower limit level setting means being set in response to the
output signal of said speed detecting means in such a manner that said
setting value fo this voltage lower limit level setting means becomes a
value lower than the setting value of said voltage limit level setting
means and also a value higher than a value corresponding to the induced
voltage internally produced from said brushless motor;
voltage limiter means for limiting the output signal of said output voltage
instucting means based on the setting value of said voltage limit level
setting means and the setting value of said voltage lower limit level
setting means to thereby supply said output voltage instruction signal to
said drive circuit, and for limiting the upper limit value and the lower
limit value of the output voltage of said drive circuit;
reverse rotation limiter means for detecting as to whether or not a reverse
rotation speed of said brushless motor reaches a preset reverse rotation
limit level based upon the detection signal of said speed detecting means,
and for outputting a second power supply interrupting signal when said
reverse rotation speed reaches said preset reverse rotation limiter means
is produced, the connection between said drive circuit and said brushless
motor is electrically opened;
voltage variation detecting means for detecting a variation contained in
the output voltage of said DC main power supply in a direct manner, or
based upon anyd one of an output current of said DC main power supply and
a drive current of said brushless motor; and
voltage correcting means for applying said output voltage instruction
signal to said drive circuit by conversely changing the output signal of
said voltage limiter means in order to compensate for the variation
contained in the output voltage of said DC main power supply based upon
the detection output from said voltage variation detecting means.
12. A protection apparatus of a brushless motor as claimed in claim 11
wherein:
either one or both the setting value of said voltage limit level setting
means and said setting value of said voltage lower limit level setting
means is corrected in such a manner that both a fluctuation and a
variation contained in the induced voltage internally produced from said
brushless motor, or a variation contained in the output voltage of said DC
main power supply is grasped based upon either the output current of said
DC main power supply, or the drive current of said brushless motor in
order to compensate for the fluctuation and the variation contained in the
induced voltage of said brushless motor, or the variation contained in the
output voltage of said DC main power supply.
13. A protection apparatus of a brushless motor comprising:
a brushless motor;
commutation signal detecting means for detecting a position of a movable
member of said brushless motor;
speed detecting means for detecting a rotation speed of the movable member
of said brushless motor, involving a rotation direction thereof, in
response to the detection signal outputted from said commutation signal
detecting means;
a drive circuit for producing a commutation signal used to drive the
movable member of said brushless motor in response to the detection signal
outputted from said commutation signal detecting means and for driving
said brushless motor based upon said commutation signal;
output voltage instructing means for supplying to said drive circuit, an
output voltage instruction signal for instructing an output voltage of
said drive circuit, which constitutes a drive voltage when said brushless
motor is driven;
voltage limit level setting means for setting an upper limit value of the
output voltage of said drive circuit;
voltage lower limit level setting means for setting a lower limit value of
the output voltage of said drive circuit;
voltage limiter means for limiting the output signal of said output voltage
instructing means based on the setting value of said voltage limit level
setting means to thereby limit an upper limit value of the output voltage
of said drive circuit, and also for limiting the output signal of said
output voltage instructing signal based on the setting value of said
voltage lower limit level setting means to thereby limit the lower limit
value of the output voltage of said drive circuit;
reverse rotation limiter means for detecting as to whether or not a reverse
rotation speed of said brushless motor reaches a preset reverse rotation
limit level based upon the detection signal of said speed detecting means,
and for outputting a second power supply interrupting signal when said
reverse rotation speed reaches said preset reverse rotation limit level;
low speed failure detecting means for detecting as to whether or not the
rotation speed of said brushless motor becomes below a preset low speed
failure sensing level, and for outputting a low speed failure signal when
said rotation speed becomes below said preset low speed failure sensing
level; and
low speed overload detecting means containing said low speed failure
sensing means, for latch-processing a third power supply interrupting
signal to thereby output the latch-processed third power supply
interrupting signal in the case that such a condition that said low speed
failure signal is outputted from said low speed failure sensing means and
also said second power supply interrupting signal is not outputted from
said reverse rotation limiter means is continued for a predetermined time
period; wherein:
the setting value of said voltage limit level setting means is set in
accordance with the detecting signal outputted from said speed detecting
means in such a manner that the higher the rotation speed of the movable
member of said brushless motor, said setting value becomes a large value;
the lower the rotation speed of the movable member of said brushless
motor, said setting value becomes a small value; and when the rotation
speed becomes near zero and the rotation direction is reversed, said
setting value becomes a preset constant value;
the setting value of said voltage lower limit level setting means is set in
response to the output signal of said speed detecting means in such a
manner that said setting value of this voltage lower limit level setting
means becomes a value lower than the setting value of said voltage limit
level setting means, and also a value higher than a value corresponding to
the induced voltage internally produced from the brushless motor; and
also;
when said second power supply interrupting signal outputted from said
reverse rotation limiter means, or said third power supply interrupting
signal outputted from said reverse rotation limiter means is produced,
said drive circuit is electrically opened from said brushless motor.
14. A protection apparatus of a brushless motor comprising:
a DC (direct current) main power supply;
a brushless motor;
commutation signal detecting means for detecting a position of a movable
member of said brushless motor;
speed detecting means for detecting a rotation speed of the movable member
of said brushless motor, involving a rotation direction thereof, in
response to the detection signal outputted from said commutation signal
detecting means;
a drive circuit for producing a commutation signal used to drive the
movable member of said brushless motor in response to the detection signal
outputted from said commutation signal detecting means and for driving
said brushless motor based upon said commutation signal, said drive
circuit outputting the output voltage of said DC main power supply in a
ratio responding to an output voltage instruction signal as a drive
voltage used when said brushless motor is driven;
output voltage instructing means for supplying said output voltage
instruction signal to said drive circuit;
voltage limit level setting means for setting an upper limit value of the
output voltage of said drive circuit, the setting value of said voltage
limit level setting means being set in accordance with the detecting
signal outputted from said speed detecting means in such a manner that the
higher the rotation speed of the movable member of said brushless motor,
said setting value becomes a large value; the lower the rotation speed of
the movable member of said brushless motor, said setting value becomes a
small value; and when the rotation speed becomes near zero and the
rotation direction is reversed, said setting value becomes a preset
constant value;
voltage lower limit level setting means for setting a lower limit value of
the output voltage of said drive circuit, in which the setting value of
said voltage lower limit level setting means is set in response to the
output signal of said speed detecting means in such a manner that said
setting value of this voltage lower limit level setting means becomes a
value lower than the setting value of said voltage limit level setting
means, and also becomes a value higher than a value corresponding to the
induced voltage internally produced from the brushless motor;
voltage limiter means for limiting the output signal of said output voltage
instructing means based upon the setting value of said voltage limit level
setting means and the setting value of said voltage lower limit level
setting means to thereby supply said output voltage instruction signal to
said drive circuit;
reverse rotation limiter means for detecting as to whether or not a reverse
rotation speed of said brushless motor reaches a preset reverse rotation
limit level based upon the detecting signal of said speed detecting means,
and for outputting a second power supply interrupting signal when said
reverse rotation speed reaches said preset reverse rotation limit level;
low speed failure detecting means for detecting as to whether or not the
rotation speed of said brushless motor becomes below a preset low speed
failure sensing level, a | | |
