G. Wang’s research while affiliated with University of Oklahoma and other places

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Publications (1)


Experimental Investigation on the Energy Performance of Variable Frequency Drives in HVAC Systems
  • Conference Paper

April 2017

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24 Reads

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1 Citation

K. Kiamehr

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S. Shahahmadi

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G. Wang

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Variable frequency drives (VFDs) are widely applied on induction motors that drive fans and pumps in heating, ventilation and air conditioning systems. Under partial loads, VFDs not only adjust frequency to reduce motor speed and mechanical output power (load) but also adjust voltage to reduce motor electrical input power. The ratio of voltage to frequency affects the motor efficiency. On the other hand, VFDs not only consume energy, but also create harmonics, which can cause additional motor energy losses and interfere with sensitive electronic equipment. So far, not enough studies have been done to identify the motor losses and the effects of harmonics on system energy consumption. The purpose of this paper is to experimentally investigate the additional energy loss resulted by VFDs and the optimal ratio of voltage to frequency of VFDs. First the energy consumption with different voltage-frequency ratio settings under different loads is measured on the same system to identify the optimal voltage-frequency ratio. Then the additional energy loss is identified by comparing power difference of a chilled water system with and without a VFD. The measurement results show that the VFD results in 2.5% energy loss and the optimal voltage-frequency ratio is not always the flux optimization mode.

Citations (1)


... Extra motor core losses come from voltage harmonics in VFDs, and additional motor copper losses in the stator and rotor windings result from current harmonics in VFDs (13), (9). When the motor is running at rated load, Manz and Morgan estimated an additional 5-10% more heating in the motor due to the usage of a VFD (14)(15). WEG demonstrated that at the rated speed and load, a frame 315 IEC motor operated by a PWM VFD results in 15% extra motor power losses (16), (9). ...

Reference:

Harmonic Mitigation in VFD Controlled Chiller Compressor Using AC Line Reactor and DC Link Choke Combination
Experimental Investigation on the Energy Performance of Variable Frequency Drives in HVAC Systems
  • Citing Conference Paper
  • April 2017