In this study, an analysis was performed on the AC PWM chopper technology, enabling speed control of single-phase induction motors by varying the supplied voltage. Based on the results of the analysis, program algorithms to operate the power supply unit, motor driver unit, phase detection unit, current detection unit, communications and micro-controller necessary for controlling the speed of AC motors were conceived, and the controller design method was examined.
The CE (European Conformity) marking application procedure for the controller designed in this study was proceeded for the purpose of ensuring its stability and reliability. This would secondarily enable the controller to satisfy the conditions necessary to be sold in the domestic and overseas markets including Europe.
In the conception stage, the CE mark testing standards and LVD electrical safety and EMC testing checklist were examined so as to reflect the issues in the early phase of the design stage. Afterwards, the controller was additionally improved and supplemented through a series of related tests before proceeding with the application for the CE marking.
In the test, a power meter was used to measure the power factor when operating the motor of the AC PWM chopper controller in order to confirm that the power factor, which is the most critical aspect of the AC PWM chopper-based AC-AC conversion technology, is near 1. Also, the waveforms of the current and the output voltage during motor operation were measured.
For the purpose of proving the stability and reliability of the controller, an LVD electrical safety test and an EMC test required for the CE marking were performed through SGS, a domestic company that specializes in CE certification procedures.
The defect quantity compared to the sales volume of the product was analyzed so as to prove the reliability and stability after completing the CE certification procedure and the related tests.
In conclusion, the CE marking was acquired, which verified the capacity to design a controller that satisfies the certification requirements and showed that the controller incorporated with the AC PWM chopper technology met the conditions necessary to be sold overseas.
The AC PWM chopper method controls the voltage to control the motor speed, and compared to the phase control method, the input power factor is near 1, which means that it is more efficient than its counterpart.
The quantity of defects compared to the sales volume of the product was analyzed, and the defect quantity was reduced after the CE certification procedure and the related tests, which in turn helped guarantee the product reliability and showed an improvement in stability.