Simulated energy-efficient voltage frequency ratios of Variable-frequency drives on induction motors

Gang Wang, Koosha Kiamehr

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

Variable-frequency drives (VFDs) are widely applied on induction motors that drive fans, pumps, and compressors. 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. Traditionally, VFD manufacturers recommend controlling the voltage so that it is proportional to the square of the frequency for variable torque motor loads on fans and pumps and proportional to the frequency for constant torque motor loads on compressors. The purpose of this paper is to investigate energy-efficient voltage frequency ratios of VFDs using the motor equivalent circuit method. First, the motor load and speed correlation are derived for different applications. Then, VFD voltage is optimized for a given VFD frequency to maximize motor efficiency. Finally, the motor efficiency is simulated and compared under the optimal voltage and different preset voltages. The simulation results show that the motor efficiency with the ratio of voltage to frequency to the power of 1.5 is mostly close to the optimal efficiency for variable torque motor loads, and the motor efficiency with the ratio of voltage to frequency to the power of O. 5 is mostly close to the optimal efficiency for constant torque motor loads with efficiency improvement by up to 3% over traditional ratios.

Original languageEnglish (US)
Title of host publicationASHRAE Transactions - 2016 ASHRAE Annual Conference
PublisherAmer. Soc. Heating, Ref. Air-Conditoning Eng. Inc.
Pages149-159
Number of pages11
Volume122
ISBN (Electronic)9781939200464
StatePublished - 2016
Event2016 ASHRAE Annual Conference - St. Louis, United States
Duration: Jun 25 2016Jun 29 2016

Other

Other2016 ASHRAE Annual Conference
CountryUnited States
CitySt. Louis
Period6/25/166/29/16

ASJC Scopus subject areas

  • Building and Construction
  • Mechanical Engineering

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    Wang, G., & Kiamehr, K. (2016). Simulated energy-efficient voltage frequency ratios of Variable-frequency drives on induction motors. In ASHRAE Transactions - 2016 ASHRAE Annual Conference (Vol. 122, pp. 149-159). Amer. Soc. Heating, Ref. Air-Conditoning Eng. Inc..