A method and system for suppressing grid-side current harmonics in a motor drive system without electrolytic capacitors

Abstract

A method and system for suppressing current harmonics on the grid side of a motor drive system without electrolytic capacitors belong to the field of variable frequency drives. Including one: processing the grid-side current signal, extracting the grid-side current harmonic component, after the difference between 0 and the current harmonic component is adjusted by the PI regulator and absolute valued, the inverter input power waveform correction value is generated; The phase loop obtains the phase information of the grid-side voltage. After processing, the initial value of the inverter input power waveform with twice the frequency of the grid voltage waveform is obtained. The initial value of the inverter input power waveform is corrected with the inverter input power waveform in step 1 The actual amount of the inverter input power waveform is obtained after the difference of the amount; 3: The speed loop is adjusted by the PI regulator and the output is multiplied by the actual amount of the power waveform in step 2 to obtain the inverter power given amount; 4: The inverter After the difference between the given power and the power feedback of the inverter is adjusted by the PR regulator, the given q-axis current is obtained; 5. The residual control method is the same as the traditional motor vector control method.

Description

technical field [0001] The invention belongs to the field of variable frequency drive, and in particular relates to a method and system for suppressing grid-side current harmonics of a motor drive system without electrolytic capacitors. Background technique [0002] As energy and environmental issues become more and more prominent, single-phase AC input variable frequency drive solutions have great advantages in energy saving, and are more and more widely used in household appliances such as air conditioners, refrigerators, and washing machines. The permanent magnet synchronous motor has the characteristics of high efficiency, simple structure, large overload capacity, small moment of inertia and small torque ripple, and is very suitable for the drive system of household appliances. [0003] In the traditional permanent magnet synchronous motor drive system, a large-capacity electrolytic capacitor is usually used to maintain a constant bus voltage, and a power factor correct...

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Problems solved by technology

[0004] However, due to the small bus capacitance, the bus voltage fluctuates greatly, and the removal of the power factor correction (PFC) circuit will also cause LC resonance between the grid-side filter reactor and the DC bus capacitor, which will lead to grid-side The input current has large harmonics and low power factor, which will cause pollution to the grid current

[0005] At present, the method to improve the power factor of the permanent magnet synchronous motor drive system without electrolytic capacitors is mainly to adopt the inverter power control strategy, but this control strategy does not significantly improve the grid-side power factor of the small-power motor drive system, and the grid-side current harmonics still larger

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