外文翻譯--三相電壓型pwm整流器建模和仿真研究-wenkub.com
2025-01-04 09:19 本頁(yè)面
【正文】 rqqqrddduRidtdiLuRidtdiL?????? We can see from equation that the two axis current are totally decoupled. urd’ and urq, are only related with id and iq simple proportionalintegral(PI)controllers are adopted in the current and voltage regulation. Design of outer voltage square loop Equation (3) describes the dynamics of vdc. Power balance equation can be used to derive an alternate equation for vdc dynamics. The active power absorbed from the ac source(Pac) and the active power delivered to the converter dcside (Pdc) are expressed by: ? ?? ?91823232 ?。小 cLdcdcdcdcdcqqddacVRVdtdCViViuiuP????? The relationship between Pac and Pdc is: Pac=Pdc+Ploss (10) Where Ploss includes the power loss in the resistor R as well as the switching and conduction losses in the VSR. The resistance R is always very small and thus it is practically reasonable to neglect its power loss. The rectifier losses are larger than the power loss in R but still they count for a small portion of the total power. Therefore,the rectifier losses can also be neglected without noticeable loss of accuracy. If better accuracy is desired the rectifier losses can be represented by a small resistor in series with RL. The total equivalent dcside resistance is still represented by RL. From Pac=Pdc,the following dynamic results: ? ?1123231 2 qqdddcLdcdc iuiuVRVdtdCV ??? Which can be rearranged in following form: ? ? ? ?12332 22 qqdddcLdc iCuiCuVCRVdtdV ???? Due to unidirectional nature of vdc ,Taking vdo2 as the variable,(12) will bee linear. Putting equation (8) into equation(12), ? ? ? ?1322 22 acdcLdc PCVCRVdtd ??? This is a firstorder dynamic equation with vdc2 as the state variable as well as the output,and Pac as the input. A simple PI controller can be designed to regulate the DC voltage with no steady state error. Since ud is measurable,the actual input variable id can be derived from Pac. The result is actually the reference value of id for the current inner control loop. displays inner current loop with state feedback decoupling and outer voltage square loop control system for VSR. Block diagram of double closeloop control for threephase VSR 2 Voltage Spacevector Synthesization When the urd and urq acquired the SVPWM method is realized through dq to α βtransformation to trace the AC current mand exactly and regulate the DC bus voltage. Depending on the switching state on the circuit the bridge rectifier leg voltages can assume 8 possible distinct states represented as voltage vectors (V0 to V7). V1 to V6 are six fixed nonzero vectorsV0 and V7 are two zero vectors as shown in the input three phase voltage are divided into six 60176。simulation Introduction Diode and phasecontrolled converters constitute the largest segment of power electronics that interface to the electric utility system today. These converter circuits are simple but the disadvantages are large distortion in line current and poor power factor. To bat these problems the PWM rectifier various power factor correction(PFC) techniques based on active wave shaping of the line current have been proposed. The PWM rectifier offers several advantages such as: control of DC bus voltage,bidirectional power flow unity power factor and sinusoidal line current. Many control techniques have been adopted for these rectification devices
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