外文翻譯--pwm整流器中的應(yīng)用自反饋串級(jí)調(diào)速系統(tǒng)-其他專業(yè)(已改無錯(cuò)字)
2023-03-03 09:50:27 本頁面
【正文】 ector V on the circle locus C point, current vector I is lead electromotive force vector 090E and the side of the PWM rectifier shows capacitance characteristic as . When the endpoint of voltage vector V on the circle locus D point, current vector I is parallel and the opposite direction with electromotive force vector E . The side of the PWM rectifier shows negative resistance characteristic as . （ 3） （ 4） （ 5） （ 6） So make sure the output voltage of the DC side isinvariableness, the input current and voltage of the AC side can work on negative resistance or capacitance characteristic, hence QT =0or QT=?Q1 . The power factor is increased. V. DESIGN OF THE PWM RECTIFIER CONTROL SYSTEM As the AC side of threephase PWM rectifier is timevarying, it is difficulty to design the control system. So the method of vector control of asynchronous motor is introduced. The ABC reference frame changes to dq synchronously rotating reference frame bases on the grid voltage frequency. So the sinusoidal variables in ABC reference frame bee DC variables in dq synchronously rotating reference frame. It is easy to design the control system. In the dq synchronously rotating reference frame, the q coordinate axis is coincides with the grid electromotive force vector Edq , so the d axis ponent of the electromotive force vector ed is zero. In the synchronously rotating reference frame, the q axis ponent shows the active power and the d axis shows the reactive power. In dq synchronously rotating reference frame, the model of threephase PWM rectifier is: ??????????????????? ??????????qdqdPqd vviiRLpL LRLee ? ?（ 2） In the equation mentioned above, ed ,eq is the d and q axis ponent of the electromotive force vector Edq , vd ,vq is the d and q axis ponent of the voltage vector in the AC side, id ,iq is the d and q axis ponent of the current vector in the AC side, and p is the differential operator. In the equation (2), because the d and q axis ponent is coupled, it is difficult to design the control system. So a control strategy based on the feedforward decoupling isapplied. The PI regulator is bedded in the current regulators, so the control equation of vd ,vq is: ? ?qdqqiIiPq eLiiisKKv ????????? ??? ? ? ? ?dqddiIiPd eLiiisKKv ????????? ??? ? ? (3) KiP,KiI is the proportion adjustment coefficient and the integral regulation coefficient of the current regulating loop. *, * iq id is the appointed value of iq ,id . In the voltage loop, the needed current is the three phase symmetrical sine current, and it’s the same frequency of grid voltage. So in dq synchronously rotating reference frame, ?qi and ?di are DC quantity. Hence iq and id can be adjusted smoothly by PI regulator. The equation is (4). ? ?dcdciIiPq vvsKKi ??????? ?? ??(4) Introduced the conception of instantaneous power, in the dq synchronously rotating reference frame, the instantaneous active power and reactive power of the PWM rectifier side can shows as （ 5） : ddqq eeiep ?? dqqd eeieq ?? (5) In order to pensate the inductive reactive power absorbed by motor, the PWM rectifier works in capacitive character. So id is: qd eQi ??? (6) Form the equation (3) (4) (6), the control block diagram of PWM rectifier is . VI. SIMULATION RESULTS OF THE PWM RECTIFIER CASCA
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