Abstract
Small capacitor motor drive systems have received increased attention due to higher reliability and longer lifespan. However, small capacitor motor drive systems suffer from poor dynamic performance and larger torque ripple. In this paper, a combined control method is presents to improve the performance of small capacitor motor drive systems. On the one hand, this combined control strategy adopts injected harmonic current to reduce the fluctuation voltage on the DC-link, which provide better conditions for high-performance operation of permanent magnet synchronous motor. To satisfy the harmonic standard of IEC61000-3-2, the guideline of injected harmonic current is deduced according to motor power and the input power factor. On the other hand, an improved repetitive control in parallel with PI control is applied into motor control to effectively suppress motor torque ripple under the condition of the periodic pulsation voltage on the DC-link. In addition, this control method has good dynamic motor performance. Experiments are conducted, and the results verify the feasibility and effectiveness of the combined control strategy.
Highlights
Nowadays, motor drive systems have been widely applied in industrial production and home application
For existing motor drive systems powered by the grid, a bulky electrolytic capacitor is used to absorb the grid pulsating power to keep the DC-link voltage stable, which is the basis for high motor performance [1,2]
Electrolytic capacitors are the least reliable components in drive systems, and 60% of the failures of drive systems is caused by electrolytic capacitors [3]
Summary
Motor drive systems have been widely applied in industrial production and home application. In [23,24,25], the torque-producing reference current is modified according the characteristic of DC-bus voltage or grid power, which dynamically changes the impedance of the load In these methods, the negative impedance of the motor drive system is converted into positive damping characteristics, and improve the stability of the SC motor drive system. The above analysis shows that when the reasonable 3rd harmonic current is injected into SC motor drive systems, the voltage fluctuation on the DC-link can be greatly reduced, which improve the motor performance. This system can still meet the current harmonic and input PF of IEC61000-3-2
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