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參數(shù)資料
| 型號： | M51971 |
| 廠商： | Mitsubishi Electric Corporation |
| 英文描述： | MOTOR SPEED CONTROL |
| 中文描述： | 電機轉(zhuǎn)速控制 |
| 文件頁數(shù)： | 12/13頁 |
| 文件大?。?/td> | 387K |
| 代理商： | M51971 |
MOTOR SPEED CONTROL
M51971L/FP
MITSUBISHI <CONTROL / DRIVER IC>
4. Necessity for stable control
Stable control requires the gain of G
C
(S)
G
M
(S) to be the phase
characteristics of 180 or less in a frequency area of 1 or more.
The relation of the phase and the gain is determined according to
the Baud’s theorem when all poles and zero points of the transfer
function are placed at the left side of the complex sphere.
If G
C
(j
ω
)
G
M
(j
ω
) follows the Baud’s theorem, in a frequency area
of | G
C
(j
ω
)
G
M
(j
ω
) |
≥
1 the inclination of gain of G
C
(j
ω
)
G
M
(j
ω
)
must be -12dB/oct or more for stable control.
For the reason above, when the circuit constant is selected to
achieve
ω
F1
≈ ω
M
, and the inclination of the gain of each of G
C
(j
ω
)
and G
M
(j
ω
) is -6dB/oct, that is, the following formula must be
established with respect to the frequency of
ω
F2
where the
inclination of the gain of G
C
(j
ω
)
G
M
(j
ω
) begins to be -12dB/oct.
| G
C
(j
ω
F2
)
G
M
(j
ω
F2
)
| < 1
(8)
To make a precise control, the gain of open-loop transfer function
must be large in the entire area of frequency.
The variation of the motor rotating speed attenuates due to
disturbance at an inclination of -6dB/oct with the frequency of
ω
M
or more.
The capability of rotating speed control in the frequency area from
ω
F1
to
ω
F2
is determined by the gain of open-loop transfer function
at
ω
F1
(
≈ω
M
). The following formula is established with
| G
C
(j
ω
F2
)
G
M
(j
ω
F2
)
| < 1 and when the inclination of the gain of
G
C
(j
ω
)
G
M
(j
ω
)
is almost equal to -6dB/oct with the frequency of
ω
F2
or less.
| G
C
(j
ω
M
)
G
M
(j
ω
M
)
| <
ω
F1
Improvement of control precision in the frequency area from
ω
F1
to
ω
F2
requires the following conditions.
ω
F1
≈ ω
M
(10)
ω
F2
>>
1
The K
CP
or C
F1
+ C
F2
value must be set to satisfy formulae (4) and
(5).
5. Influence on the Stability of Tacho-generator
Frequency
The control system that is controlled with tacho-generator frequ-
ency, i.e. period, is a kind of sample hold system controlled with
discrete information in the time axis.
Addition of extra phase delay to sample hold operation makes the
system more unstable.
More precise transfer function H*(
j
ω
) (G
C
*(
j
ω
)
G
M
*(
j
ω
)) taking the
above operation into account is as follows, when H(
j
ω
)(G
C
(
j
ω
)
G
M
(
j
ω
)) is assumed to be the transfer function where this opera-
tion is not taken into account:
Where:
ω
G
: Set value of tacho-generator frequency
That is, extra phase delay of 2
πω
/
ω
G
(radian) must be taken into
account.
That is, if the angular frequency satisfying | G
C
*(
j
ω
)
G
M
*(
j
ω
)
| = 1
is assumed to be
ω
od
B
, the following relation must be established.
ω
G
> 4
ω
od
B
(13)
When this determines
ω
G
, the possible gain of open-loop transfer
function with
ω
M
can be obtained.
This formula (14) must be satisfied in the control system using the
frequency of the tacho-generator regardless of the control system
and indicates that the upper limit value of the control gain with
ω
M
is inevitably determined when the motor and tacho-generator are
determined.
Improvement of the control precision in the rotating speed requires
| Gc(
j
ω
M
)
G
M
(
j
ω
M
)
| >> 1. The following formula must be there-
fore established.
ω
G
(15)
>> 1
6. Conclusion
According to the theoretical consideration above, the design of
speed control system making the best use of the characteristics of
the motor is described as follows:
If
ω
M
sharply changes with motor load changed, a circuit constant
is desirable to be set around minimum
ω
M
.
As C
F1
is smaller, influence by
ω
F2
becomes smaller, but the
peak-to-peak value of the output pin waveform becomes larger and
the drive waveform becomes closer to pulse shape.
In most of design cases, both sides are therefore desirable to be
equal.
(3) Selection of gain constant
Keeping the relation satisfying formulae (16) and (17) above,
obtain a value for stable control by changing the K
CP
or C
F1
+C
F2
value.
If the motor set speed is divided into several stages, stage of lower
speed is less stable. In this case, experiment must be made at
lower speeds.
ω
F2
≈ω
M
F2
(9)
ω
F1
(11)
H*(
j
ω
) =
π
(
ω
/
ω
G
)
si
n
π
(
ω
/
ω
G
)
e
– j
ω
G
2
πω
∞
H(
j
ω
+ jn
ω
G
)
n = –
∞
(12)
| G
C
(
j
ω
M
)
G
M
(
j
ω
M
)
| < 0.357 x
ω
M
ω
G
(14)
0.357
ω
M
(1)
ω
F1
≡
R
F
C
F2
1
(16)
≈ ω
M
(2)
ω
F2
≡
R
F
C
F1
C
F2
C
F1
+C
F2
(17)
ω
G
≥
4
1
相關PDF資料 |
PDF描述 |
|---|---|
| M51971FP | MOTOR SPEED CONTROL |
| M51971L | MOTOR SPEED CONTROL |
| M51977FP | SWITCHING REGULATIR CONTROL |
| M51977P | SWITCHING REGULATIR CONTROL |
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| M51971FP | 制造商:MITSUBISHI 制造商全稱:Mitsubishi Electric Semiconductor 功能描述:MOTOR SPEED CONTROL |
| M51971L | 制造商:MITSUBISHI 制造商全稱:Mitsubishi Electric Semiconductor 功能描述:MOTOR SPEED CONTROL |
| M51977FP | 制造商:MITSUBISHI 制造商全稱:Mitsubishi Electric Semiconductor 功能描述:SWITCHING REGULATIR CONTROL |
| M51977P | 制造商:Panasonic Industrial Company 功能描述:IC SUBBING WITH PQVIM51977P |
| M51978FP | 制造商:MITSUBISHI 制造商全稱:Mitsubishi Electric Semiconductor 功能描述:SWITCHING REGULATOR CONTROL |
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