Introduce for DC Inverter Type Micro Refrigeration Cooling System (MRCS) |
Mar 09, 2009 |
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What is Inverter technology?
Inverter is a device which supplies variable frequency of power supply on equipments. Because of the speed of motor is determined by the frequency of the power and the number of poles in stator winding , according to the relation. |
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where
RPM = Revolutions per minute
p = Number of poles
f = Frequency
By change the frequency of the voltage applied to the motor, the speed will be changed.
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Function of Inverter
The inverter is made up primarily of modules that are each made up of a transistor and diode in combination with each other which inverts the DC energy back to AC |
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By switching the inverter-transistor devices on and off many times per half cycle, a AC-similar current waveform is approximated. At the same time we can input variable frequency that determined by system requirement.
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Fig 1. Electronic diagram of Inverter
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So it is possible that we can control the speed of motor by changing frequency by inverter technology. That is to say, in the situation of Xpressar system, the temperature of CPU can be maintain at some level we want by it’s PWM signal that output to the inverter module of driver board.
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Fig 2. Control mechanism of inverter
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Fig 3. Speed control of compressor
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Why use DC motor?
First of all, we need to know what’s the difference between the DC & AC Motor.
【The AC Motor】: |
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(1) Current goes through the coil on the stator and the rotating magnetic field is generated.
(2) Being induced by the rotating magnetic field, induced current is generated on the rotor (squirrel cage).
(3)
According to the interaction force between current and magnetic field, the squirrel on which the induced current goes through turns around. |
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Fig 6. Squirrel Cage Rotor
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【The DC Motor】:
First of all, we need to know what’s the difference between the DC & AC Motor.
【The AC Motor】: |
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The biggest and only difference is that rotor is made of permanent magnet, but the principle of the operation is completely different from that of an AC motor.. |
Fig 7. Stator and Rotor of DC Motor
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(1) Current goes through the coil on the stator and rotating magnetic field is generated (same as AC)
(2) By the interaction of the pole of the magnet, rotor will rotate. |
Fig 8. The motion of DC motor
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Advantage of DC Motor
- Less loss and better efficiency than AC motor, because of no motor slip & no induced current loss.
- Less noise than AC motor, because there is no induction effect between stator and rotor.
- Low friction loss , because there is no brush in the motor. |
‧In order to attain better efficiency, it will be reduce the compressor speed, than reduce energy consumption when In partial load conditions. DC motor has been known as much more efficient motor than AC, and its efficiency is roughly double compared to AC. (it means energy consumption becomes half at the same condition.)
‧In conclusion, DC Inverter type compressor is a good solution for reducing energy consumption, this is so called “Eco-Friendly” technology. |
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| For more information, please check www.xpressar.com |
