1、外文原文 Principle, Modeling and Control of DC-DC Convertors for EV ZHAN G Cheng-ning , SUN Feng-chun , ZHAN G Wang (School of Vehicle and Transportation Engineering , Beijing Institute of Technology , Beijing 100081) Abstract : DC-DC convertors can convert the EV s high-voltage DC power supply into the
2、 lowvoltage DC power supply. In order to design an excellent convertor one must be guided by theory of automatic control. The principle and the method of design, modeling and control for DC-DC convertors of EV are introduced. The method of the system-response to a unit step-function input and the fr
3、equency-response method are applied to researching the convertors mat- hematics model and control characteristic. Experiments show that the designed DC-DC convertor s output voltage precision is high , the antijamming ability is strong and the adjustable performance is fast and smooth. Key words: EV
4、 ； DC-DC convertors ； automatic control ； mathematics model ； Bode drawing CLC number : U 469-72 Document code : A Generally there are two power supplies in EV. One is the DC high-voltage power supply that is used by high power devices such as traction motors and air conditioners etc. The other is t
5、he DC low-voltage power supply that is usually used in some control circuit and low-voltage electrical devices such as the inst- rument and lighting. It s rating voltage is 24 V or 12 V. The low-voltage power supply can be gained from the high-voltage power supply by a DC-DC conver- tor. In this pap
6、er, the main performance of the designed convertor is that the input voltage range is from DC 250 V to DC 450 V , the output voltage is DC 24 V , the maximum output current is DC 20 A , and the output precision is 1 %. 1 Principle of the Convertor 1.1 The Block Diagram of the DC-DC Convertor The blo
7、ck diagram of the DC-DC convertor is showed in Fig. 1. The battery series provide the DC high-voltage input Us. The low-voltage output of the con- vertor is Uo. The setting value Ui of the convertor is equal to or is in proportion to the demanded output voltage Uo. The convertor is a closed-loop neg
8、ative feedback-system with voltage feedback. 1.2 Power Switch Circuit The power switch circuit with semi-bridge mode is showed in Fig. 2. L1 and C1 constitute an input filter to avoid high-frequency impulses flowing bac- kwards. Capacitors C2and C3 constitute the partial-voltage circuit while resist
9、- ances R1 and R2do so. IGBT1 and IGBT2 are semiconductor switch devices. C6 is a separation DC capacitor. T1 is a transformer that reduces the voltage. L2 and C7 constitute an output filter. RL is the load resistance. When the PWM signals in the reverse semi-waves are inputted onto IGBT1 and IGBT2
10、s control poles , the corresponding DC voltage can be yielded from the convertor. Fig. 2 Principle circuit of power switch with semi-bridge mode 1.3 Control Circuit The chip SG3525 is used in the PWM control circuit showed in Fig. 3. V cc is the power voltage applied to the chip, it is 12.0 V. A bas
11、e-voltage of 5.1 V is yielded on pin16 of the chip that is partially used as parameter voltage input Ui. The chip includes a sawtooth-wave generator. Rt and Ct are the external resis- tance and capacity that determine the sawtooth-wave s frequency.Pin2 of the chip is a positive-phase input port. Voltage input Ui is putted to the port, here Ui =2. 5 V. Pin1 of the chip is the negative-phase input port where the feedback voltage is inputted.Pin9 of the chip is the output end of the inside amplifier of the chip. The proper resistance and capacitor are connected between the pin1 and
