【正文】 An individual power supply is needed if an optocoupler is used, which increases the plexity of the system. So the isolationcircuit adopt s a pulsetransformer showed in Fig. 4. Transistors BG1 and BG2 in Fig. 4 pose a plementation power amplification circuit. T2 is the pulsetransformer that isolates the power circuit from the control circuit. R5 and C8 pose the acceleration circuit. The diode D6 eliminates negative impulses. The diode D7 and transistor BG3 pose the rapid discharge circuit of the distributing capacitor at the control pole of IGBT. Fig. 4 Principle circuit for IGBT drive 2 Modeling and Control Modeling The DCDC convertor is a voltage negative feedbacksystem. Aiming to obtain the better dynamic and static characteristic we must model and analyse it in theory. According to Ref. [ 1 ] ,DCDC convertors are the approximate secondorder systems. In order to obtain accurate parameters , the method of the systemresponse to a unit stepfunction input is adopted in this paper. Measuring the OpenLoop System’ s Response to a Unit StepFunction Input The block diagram for measuring is shown in Fig. 5. The concrete method is described as follows : ① The voltage feedback signal is cut off 。 自動控制 。變頻器的調(diào)定值 Ui 等于或者是按比例到要求的輸出電壓 Uo。 C8 是積分電容，采用整體補償系統(tǒng)的補償制度， PWM 脈沖從腳 11 和腳 4產(chǎn)生，當 PWM 控制電路正常運行時，腳 2 上的 Ui 和腳 1上的 Ub應該平衡，當 Ui 不等于 Ub時， PWM 技術寬度可自動調(diào)節(jié) PWM 控制電路使 Ui 等于 Ub，通過這種方法我們可以控制變壓器的輸出電壓。 輸出和輸入的增量的比 Ko=dUo/ dUi=10/ 1=10. 圖 5 開環(huán)系統(tǒng)測量原理框圖 圖 6 對單位階躍函數(shù)輸入系統(tǒng)響應 2曲線③和⑥分別獲得頻率特性和對數(shù)相頻特性的開環(huán)系統(tǒng)的補償。它的初始階段 ω c = 1 016 rad/ s，相位邊緣 γ = 176。 2 開環(huán)傳遞函數(shù)的確定 根據(jù)參考 【 3】， 我們有阻尼 比ξ、被控制對象 Gp ( s)、固有頻率 ω n 無阻尼自由振動微分方程： 為了確保輸出電壓 Uo= 電壓反饋給 SG3525 腳 1 的為，來平衡輸出電壓 Ui= 時，我們采用反饋和測量的參數(shù) Kb = Ub/ Uo = ( 4 ) 2 4 驅動電路 IGBT 驅動電路通常采用脈沖變壓器或光耦合器通過控制電路隔離電源電路 ，如果光耦合器需要使用個人電源，就會增加系統(tǒng)的復雜度，所以隔離電路采用脈沖變壓器如圖 4 所示，如圖 4中晶體管 BG1 和 BG2 組成一個互補的功率放大電路， T2 是控制電路中的脈沖變壓器隔離電路， R5和 C8 組成加速電路，二極管 D6消除負脈沖，二極管 D7和晶體管 BG3 在 IGBT 的控制下組成快速放電電路分布電容。 1 Bode 圖 中圖分類號 U 469172 文獻標識碼 A 通常有兩種電源電動汽車。 ③ Ui0 is superimposed with d Ui that is posed by positive and negative rectangle wave impulses. The amplitude of d Ui is taken to be equal to . It should make d Uo be easy to be observed to select the rectangle wave frequency , adopting f 1 = 400 Hz 。 DCDC convertors 。 output and input’ s incremental ratio K0 = d Uo/ d Ui = 10/ 1 = 10. The measuring block diagram of the openloop system Fig. 6 The systemresponse to a unit stepfunction input Determining the OpenLoop Transfer Function According to Ref s. [2,3 ] , we have the damping ratio ξ , undamped natural frequency ω n and transfer function of controlled object Gp ( s) as follows : In order to ensure that when the output voltage Uo =24 V the feedback voltage to pin1 of the SG3525 is V to balance the in