Control Device and Method for Controlling an AC Motor
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Abstract
Control device (30) and method for controlling an AC motor (18) by means of a motor control unit (19). The control device (30) includes an AFE unit (33) arranged in parallel with the rectifier unit (12), which AFE unit (33) is arranged for, under normal operation, to work as an active filter and inject super-harmonic current components opposite of the ones generated by the rectifier unit (12) to counteract the current distortion, seen from the grid side. When the motor control unit (19) is running regenerative, the AFE unit (33) will work as a 4-quadrant converter and supply energy back to the supply grid (13). Advantages of the invention are reduced physical size, lower cost and improved efficiency compared to existing solutions of motor drive with frequency converters in weak grids, where the motor drive must handle regenerative operation.
34 Citations
40 Claims
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1-20. -20. (canceled)
- 21. A control device (30) for controlling an AC motor (18) by means of a motor control unit (19), including a rectifier unit (12), an AFE unit (33) which includes one or more LCL filters (35), an AC/DC converter (36), and an Active Front End control (37), which control the device (30) being supplied with energy from a supply source/supply grid (13), wherein the AFE unit (33) is arranged in parallel with the rectifier unit (12), for working as an active filter and injecting super-harmonic current components opposite to those generated by the rectifier unit (12) to counteract the current distortion on the grid side under normal operation, and regeneratively working as a 4-wuadrant converter and supplying energy back to the supply grid (13) when the motor control unit (19) is running.
- 33. A method for controlling an AC motor (18) by means of a motor control unit (19), a control device (30) including a rectifier unit (12), an AFE unit (33) which include one or more LCL filters (35), an AC/DC converter (36), and an Active Front End control (37), wherein the control device (30) is supplied with energy from a supply source/supply grid (13), including by means of the AFE unit (33), which is arranged in parallel with the rectifier unit (12), actively filtering and injecting super-harmonic current components opposite to the ones generated by the rectifier unit (12) to counteract the current distortion, seen from the grid side, when the motor control unit (19) operates an AC motor (18).
Specification