A non-electrolytic capacitor variable frequency drive control system and control method

Abstract

The invention relates to a control method of a variable frequency drive system without electrolytic capacitors, comprising: collecting the phase angle of the network side and the real-time current of any two phases in the three-phase power supply of the motor; performing Clark transformation and Park transformation on the real-time current to obtain α Axis current, β-axis current, d-axis real-time current and q-axis real-time current; calculate q-axis given current and d-axis given current; calculate d-axis error current and q-axis error current, respectively for d-axis error current and q-axis The error current is adjusted to obtain the given voltage of the d-axis and the given voltage of the q-axis; the Park inverse transformation is performed on it to obtain the given voltage of the α-axis and the given voltage of the β-axis; the inverter is pulse-width modulated, and passed The inverter controls the motor. The invention can realize the high-speed operation of the motor in the magnetic field weakening area, can obtain high power factor on the grid side, can optimize the phase current of the motor, improves system reliability, and has simple and effective control, and is suitable for application in the field of household appliances.

Description

technical field [0001] The invention relates to the field of variable frequency drives, in particular to a control system and a control method for a variable frequency drive without an electrolytic capacitor. Background technique [0002] As energy and environmental issues become more and more prominent, single-phase AC input variable frequency drive schemes are widely used in household appliances such as air conditioners, refrigerators, and washing machines because of their huge advantages in energy saving. Because the permanent magnet synchronous motor has the characteristics of high efficiency, simple structure, large overload capacity, small moment of inertia and small torque ripple, it is very suitable for the drive system of household appliances. [0003] In the case of single-phase AC input variable frequency drive, due to the imbalance of input and output instantaneous power, large electrolytic capacitors have to be widely used on the bus side to buffer energy, and b...

AI Technical Summary

Problems solved by technology

However, large electrolytic capacitors have the following disadvantages: 1) The capacity of electrolytic capacitors fluctuates greatly with changes in temperature and frequency, especially when electrolytic capacitors are used at high temperatures, the electrolyte will volatilize, resulting in a decrease in capacitance

When the capacitance drops to 60% of the initial value, it is generally regarded as the end of the capacitor life, which seriously affects the system efficiency and stability and reliability; 3) The electrolytic capacitor used for power decoupling is usually large in size, which limits the power converter. Increased Power Density

4) The busbar adopts a large electrolytic capacitor, and the current quality of the input side is poor

However, the actual direct zero vector adjustment range is limited, and it is difficult to achieve the desired effect

Moreover, the topology is complex and additional switching devices increase energy consumption

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