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參數(shù)資料
| 型號(hào)： | AD7874SQ |
| 廠商： | Analog Devices Inc |
| 文件頁(yè)數(shù)： | 4/16頁(yè) |
| 文件大?。?/td> | 0K |
| 描述： | IC DAS 12BIT 4CH 5V 28-CDIP |
| 標(biāo)準(zhǔn)包裝： | 1 |
| 類型： | 數(shù)據(jù)采集系統(tǒng)（DAS） |
| 分辨率（位）： | 12 b |
| 采樣率（每秒）： | 116k |
| 數(shù)據(jù)接口： | 并聯(lián) |
| 電壓電源： | 雙 ± |
| 電源電壓： | ±5V |
| 工作溫度： | -55°C ~ 125°C |
| 安裝類型： | 通孔 |
| 封裝/外殼： | 28-CDIP（0.600"，15.24mm） |
| 供應(yīng)商設(shè)備封裝： | 28-CDIP |
| 包裝： | 管件 |
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AD7874
REV. C
–12–
APPLICATIONS
Vector Motor Control
The current drawn by a motor can be split into two compo-
nents: one produces torque and the other produces magnetic
flux. For optimal performance of the motor, these two compo-
nents should be controlled independently. In conventional
methods of controlling a three-phase motor, the current (or
voltage) supplied to the motor and the frequency of the drive are
the basic control variables. However, both the torque and flux
are functions of current (or voltage) and frequency. This cou-
pling effect can reduce the performance of the motor because,
for example, if the torque is increased by increasing the fre-
quency, the flux tends to decrease.
Vector control of an ac motor involves controlling phase in addi-
tion to drive and current frequency. Controlling the phase of the
motor requires feedback information on the position of the rotor
relative to the rotating magnetic field in the motor. Using this
information, a vector controller mathematically transforms the
three phase drive currents into separate torque and flux compo-
nents. The AD7874, with its four-channel simultaneous sam-
pling capability, is ideally suited for use in vector motor control
applications.
A block diagram of a vector motor control application using the
AD7874 is shown in Figure 17. The position of the field is de-
rived by determining the current in each phase of the motor.
Only two phase currents need to be measured because the third
can be calculated if two phases are known. Channel 1 and
Channel 2 of the AD7874 are used to digitize this information.
Simultaneous sampling is critical to maintain the relative phase
information between the two channels. A current sensing isola-
tion amplifier, transformer or Hall effect sensor is used between
the motor and the AD7874. Rotor information is obtained by
measuring the voltage from two of the inputs to the motor.
Channel 3 and Channel 4 of the AD7874 are used to obtain this
information. Once again the relative phase of the two channels
is important. A DSP microprocessor is used to perform the
mathematical transformations and control loop calculations on
the information fed back by the AD7874.
VOLTAGE
ATTENUATORS
DAC
TORQUE
SETPOINT
IN1
V
VIN4
V
IN3
V
IN2
*ADDITIONAL PINS OMITTED FOR CLARITY
TORQUE & FLUX
CONTROL LOOP
CALCULATIONS &
TWO TO THREE
PHASE
INFORMATION
TRANSFORMATION
TO TORQUE &
FLUX CURRENT
COMPONENTS
FLUX
SETPOINT
DRIVE
CIRCUITRY
ISOLATION
AMPLIFIERS
AD7874*
DSP
MICROPROCESSOR
I
C
I
B
I
A
V
B
V
A
3
PHASE
MOTOR
Figure 17. Vector Motor Control Using the AD7874
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| AD7875BQ | 功能描述:IC ADC 12BIT SAMPLING 5V 24CDIP RoHS:否 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉(zhuǎn)換器 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 位數(shù):14 采樣率（每秒）:83k 數(shù)據(jù)接口:串行，并聯(lián) 轉(zhuǎn)換器數(shù)目:1 功率耗散（最大）:95mW 電壓電源:雙 ± 工作溫度:0°C ~ 70°C 安裝類型:通孔 封裝/外殼:28-DIP（0.600"，15.24mm） 供應(yīng)商設(shè)備封裝:28-PDIP 包裝:管件 輸入數(shù)目和類型:1 個(gè)單端，雙極 |
| AD7875CQ | 功能描述:IC ADC 12BIT SAMPLING 5V 24CDIP RoHS:否 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉(zhuǎn)換器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:250 系列:- 位數(shù):12 采樣率（每秒）:1.8M 數(shù)據(jù)接口:并聯(lián) 轉(zhuǎn)換器數(shù)目:1 功率耗散（最大）:1.82W 電壓電源:模擬和數(shù)字 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-LQFP 供應(yīng)商設(shè)備封裝:48-LQFP（7x7） 包裝:管件 輸入數(shù)目和類型:2 個(gè)單端，單極 |
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