A DC link capacitor minimization method through direct capacitor current control

Bon-gwan Gu, Kwanghee Nam
Conference Record of the 2002 IEEE Industry Applications Conference. 37th IAS Annual Meeting (Cat. No.02CH37344)  
If we make the converter side dc link current the same as the inverter side dc link current in a PWM converter-inverter system, no current will flow through the dc link capacitor and as a result, no dc link voltage variation occurs. This leads to the possibility of reducing extremely small the size of dc link capacitors which are expensive, bulky, and have a lifetime limit, if we can manage to match inverter and converter currents at the dc link. However, a converter inherently involves a delay
more » ... ly involves a delay in supplying the required current. Therefore, matching the converter current to the inverter current necessitates the use of differentiator to meet the requirements of a fast dynamic response. But in practice, differentiating the measured value is almost impossible. In this paper, we propose a new differentiation method that utilizes a one-step predictor developed from converter and inverter dynamics. In the model, the dc link voltage is regarded a variable. Since the inverter current compensation term is applied in terms of voltage, the response is fast. Simulation and experiments are performed with only 40µF dc link capacitance for a 9kW motor, and the results support the validity of the proposed scheme. 811 0-7803-7420-7/02/$17.00 © 2002 IEEE
doi:10.1109/ias.2002.1042652 fatcat:k2ztrylqqrerfif3qjic6rbmwy