Three-Phase AC Motor Drive Control Device Phase Command Calculation
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Solution Overview
Problem
Existing three-phase AC motor drive control devices face challenges in maintaining reliable rectangular wave voltage control at high-speed rotation ranges, where calculation time constraints lead to potential loss of synchronism and inadequate inverter control.
Innovation Solution
A three-phase AC motor drive control device that employs a phase command calculating section for torque feedback calculation and a pulse pattern output section to generate a switching command based on a phase command, which is phase-shifted from a basic phase, ensuring continuous pulse pattern generation and accurate torque control even at high rotation speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If rectangular wave voltage phase control is used to improve three-phase AC motor output, then motor output is improved, but calculation time increases and control reliability deteriorates at high-speed rotation ranges
Solution Approach 1:
The control device is divided into two independent functional sections: a phase command calculating section that executes torque feedback calculation and stores phase commands, and a pulse pattern output section that generates switching commands based on stored phase commands. This segmentation allows the calculation and output functions to operate independently and simultaneously, resolving the timing conflict at high rotation speeds.
Solution Approach 2:
The phase command calculating section executes torque feedback calculation and stores the phase command in advance before the pulse pattern output section needs it. By performing the calculation ahead of time and maintaining a stored phase command, the system ensures that switching commands can be generated immediately without waiting for calculation completion, thus maintaining control reliability at high speeds.
2Measurement precision
If torque feedback calculation is executed in real-time to maintain accurate torque control, then torque control precision is improved, but calculation time consumption increases and may cause loss of synchronism
Solution Approach 1:
The phase command calculating section performs torque feedback calculation and stores the phase command in advance. This preliminary action ensures that the calculation is completed before the pulse pattern output section requires the data, eliminating timing delays and preventing loss of synchronism while maintaining accurate torque control.
Solution Approach 2:
The phase command calculating section continuously executes torque feedback calculation and updates the stored phase command without interruption. This continuous operation ensures that the latest torque control data is always available to the pulse pattern output section, maintaining both precision and timing synchronization at all rotation speeds.
3Speed
If switching commands are generated based on real-time calculation to maintain control responsiveness, then control responsiveness is improved, but calculation load increases and may exceed processing capacity at high speeds
Solution Approach 1:
By dividing the control device into a phase command calculating section and a pulse pattern output section, the system separates the heavy calculation task from the command generation task. The calculating section focuses on torque feedback computation while the output section handles switching command generation using pre-calculated phase commands, reducing the processing burden on any single component.
Solution Approach 2:
The phase command calculating section completes torque feedback calculation and stores the phase command in advance, so the pulse pattern output section can generate switching commands without performing complex calculations. This preliminary calculation approach maintains control responsiveness while significantly reducing the real-time processing load during high-speed operation.
Data Source
AI summary
A three-phase AC motor drive control device has a phase command calculation unit. When driving a three-phase AC motor by a three-phase alternating square-wave voltage that is converted in power according to a switching command corresponding to one cycle of the electrical angle obtained from a rotational position of the rotor of the three-phase AC motor, the phase command calculation unit performs a torque feedback calculation based on a torque deviation, obtains, based on this calculation result, a phase command that is the lead or lag angle amount of a phase to be corrected, and stores and updates this obtained phase command. To generate the switching command, the three-phase AC motor drive control device outputs a pulse pattern to an inverter, the pulse pattern being shifted in phase by the amount of the phase command with respect to the basic phase of the three-phase alternating square-wave voltage uniquely determined with respect to the one cycle of the electrical angle.