Dsp-based Variable Frequency Power Supply Design

This dissertation presents the structure, the principle and the design of frequency-variable power system with the application of DSP (Digital Signal Processor )and IPM (Intelligent Power Module) . The system consists of the AC input stage, single phase PFC, main inverter, output low-pass filter, auxiliary power supply, etc.The power supply extremely has an important position in the electronics equipments. According to the following design theory: the DSP calculates in real time and produces three phases SPWM waves to control the on or off of the 6 IGBTs in IPM respectively. IPM then inverts the commutated single phase direct current (Insulated Gate Bipolar Transistor)into three phases alternating current. When modulated signals of SPWM are changed, the on-off time of switches also changes, so as to the voltage and frequency of output signals. The hard core of this device is the TMS320F240 DSP chip and the 6MBP25RA120 IPM chip. The foundation theory is SPWM.In the design, adopt TMS320F240DSP chip to perform real-time calculation and control. DSP chip's high calculating speed guarantees not only the real-time output of SPWM waves but also the respondence to the intelligent interface and the communication with PC. The intelligent power module inverts the direct current and also it protects the system for its safe protectfunction-short-circuit protection, over heat protection, over-current protection etc. Theadoption of a real-time SPWM calculational methods used a combination of lookup-table and interpolation guarantees the accuracy of the output alternating current. Intelligent interface and the communication between the DSP and PC make the power supply device friendly to the user. The whole system adopts close-loop control. The adoption of special arithmetic guarantees the frequency and the voltage of the output alternating current to be more accurate.This design has compact structure and maturing function. Furthermore, it is easy to upgrade and expand with function. The design fully expresses the switching power supply device's developmental tendency of high frequency, digitization and modularization that makes it more practical in reality.