Research & Design Of A Single-Phase Controller With Variable Voltage Variable Frequency

The basic principle of the single-phase SPWM technology is introduced in this paper. It presents an output signal of SPWM and sets up the mathematical model so as to analyze the harmonic distortion of them under ideal conditions. What's more, by using the simulation software tools such as fast fourier transform algorithm (FFT) of Pspice, the principle is verified and proved to be true, so it provided the warrant for the design.Based on one-single-chip integration thoughts, the single-phase controller with variable voltage variable frequency(VVVF) is designed to generate complementary doubled SPWM switch signals for the single-phase DC-AC inverter by using newly structured and digital & analog combined methods .According to the design parameters and design methods, the controller contains three main parts. The first part is to design the frequency modulation circuit which is composed of voltage controlled oscillator (VCO), reversible counter, encoder, etc. The second part is to design the sine wave networks circuits which is composed of sinusoidal current source array and switches, current to voltage converter (I-V converter), two staged LPF, etc. The third part is to design the amplitude modulation circuit which is composed of analog multiplier and two input & one output circuit, etc. Every cell-circuit is designed in transistor level according to the designing request and simulated by Pspice.It can draw a conclusion from the simulation results that the single-phase controller with VVVF can adjust the frequency and amplitude to make U/f equal to a constant so as to achieve the functions of VVVF.