Research On Dead-time Issues In SPWM Inverter Control By DSP

With the development of the technology, the application of AC drive system becomes more and more popular. In order to protect the power in DC side, dead-time is often added into the drive signals of the switches, while the dead-time added would bring many negative effects in the AC drive system during its practical running. Therefore, the compensation of the dead-time becomes one of the most popular and difficult problems in the AC drive system.The issue of the dead-time in the voltage-fed inverters under the control of the DSP in the AC drive system is studied in paper. After the concise introduction of the SPWM and the derivation of the problem of the dead-time, the causation of the dead-time and the voltage error wave of the output of the inverter which is caused by the dead-time are study in the paper. From the result of the study, the relationship between the voltage error wave which is caused by the added dead-time and the parameters of the inverter is clarified.To sum up, in this paper the problem of the dead-time in the inverter controlled by DSP is studied. First of all, the theory of the PWM and the method of the addition of the dead-time are clarified. Then the distortion of the voltage wave which would be caused by the dead-time is analyzed. Basic on of summarizing the methods in common use of the dead-time compensation, there are two more practical dead-time compensation methods offered. One is based on the invalid apparatus principle, and the other is based on integration of the invalid apparatus principle and current feedback. The result of the simulation indicates that comparing the stator current before the compensation with the stator current of motor which used the two methods to compensation the dead-time, its aberration is obviously improved. In order to validate the practical trial effect of the two methods, some preparations have been done for the testing.