Comparison VSI and PWM drives in an aluminum rolling mill ingot preheating application

Rising concern about work environments and power system efficiency has prompted careful evaluation of adjustable speed drive applications. A case study is presented from data collected in a large industrial facility. A brief description of the process precedes comparisons of pulsewidth modulated (PWM) variable frequency drives to six-step voltage source (VSI) variable frequency drives on a variable torque load. The two types of drive are installed in similar systems. Motor acoustical noise and harmonic current injection into the power distribution system are examined. Test methods and results are discussed.<
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