U.S. Variable Frequency Drive Market Size, By Voltage (Low, Medium), By Drive (AC, DC, Servo), By Application (Pump, Fan, Conveyor, Compressor, Extruder), By End-use (Oil & Gas, Power Generation, Mining & Metals, Pulp & Paper, Marine), COVID-19 Impact Analysis, Country Outlook, Application Potential, Competitive Market Share & Forecast, 2022 – 2028