The popularity of smaller AC induction motors in lower cost and higher volume markets (appliances, vending machines, etc.) has fostered its use in VSDs in industrial and factory automation markets.
The AC induction motor is a brushless AC motor with demonstrated longer life and lower maintenance performance. Power electronics packages continue to drop in price as quantities begin to climb and the semiconductor industry’s manufacturing processes shrink electronic device size and package more components on a smaller volume of silicon. Of the many types of VSDs used, the inverter driven threephase VSD and the singlephase control VSD are currently the most popular.
Benefits and disadvantages of the brushless AC VSD versus the brush DCVSD can be seen in the following comparison. The 90-watt, single-phase ES01+VS1590A VSD and the 200-watt, three-phase BHF62AT VSD from Oriental Motor represent two different AC closed-loop control schemes. The ES01 AC VSD uses a pulse generator to control speed regulation over a 17.8 to 1 speed range. The larger three-phase BHF62AT AC VSD uses a sensorless vector closed-loop control with inverter drive. The two AC VSDs show similar regulation capabilities to the 90-watt brush DC VSD using a closed-loop back EMF control scheme. The DC motor has a wider speed range and better power efficiency, but its major limitations are in life cycle costs and EMI performance. (The brush DC motor generates large amounts of EMI.) While the DC VSD has lower acquisition, installation, and operating costs, the unit life expectancy is much shorter (due primarily to motor brush life). The lower performance AC induction motors achieve the same acquisition costs as the brush DC VSD at a longer life expectancy and much lower EMI levels.
The AC induction motor is a brushless AC motor with demonstrated longer life and lower maintenance performance. Power electronics packages continue to drop in price as quantities begin to climb and the semiconductor industry’s manufacturing processes shrink electronic device size and package more components on a smaller volume of silicon. Of the many types of VSDs used, the inverter driven threephase VSD and the singlephase control VSD are currently the most popular.
Benefits and disadvantages of the brushless AC VSD versus the brush DCVSD can be seen in the following comparison. The 90-watt, single-phase ES01+VS1590A VSD and the 200-watt, three-phase BHF62AT VSD from Oriental Motor represent two different AC closed-loop control schemes. The ES01 AC VSD uses a pulse generator to control speed regulation over a 17.8 to 1 speed range. The larger three-phase BHF62AT AC VSD uses a sensorless vector closed-loop control with inverter drive. The two AC VSDs show similar regulation capabilities to the 90-watt brush DC VSD using a closed-loop back EMF control scheme. The DC motor has a wider speed range and better power efficiency, but its major limitations are in life cycle costs and EMI performance. (The brush DC motor generates large amounts of EMI.) While the DC VSD has lower acquisition, installation, and operating costs, the unit life expectancy is much shorter (due primarily to motor brush life). The lower performance AC induction motors achieve the same acquisition costs as the brush DC VSD at a longer life expectancy and much lower EMI levels.
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