The core characteristics of SPWM inverters are reflected in the following aspects:
Simplified control structure: The main circuit of this type of inverter usually only contains one controllable power link, with fewer switching elements, which greatly simplifies the structure of the control circuit. In addition, an uncontrollable rectifier is used on the rectification side, which makes the power factor of the grid close to 1 and independent of the output voltage of the inverter.
Optimized dynamic response: In SPWM inverters, variable voltage and variable frequency (VVVF) control is implemented in the same link, without relying on intermediate energy storage components, thereby accelerating the dynamic response speed of the inverter.
Harmonic suppression: By precise control of the PWM control method, SPWM inverters can effectively suppress or eliminate high (low) order harmonics, achieving output AC voltage waveforms close to sinusoidal shapes, which is crucial for reducing motor losses and noise.
2、 Working principle of SPWM inverter
The working principle of SPWM inverter involves several key components and steps:
Rectification and filtering: The three-phase AC voltage is first converted into DC voltage through an uncontrollable rectification unit, and then filtered through capacitors to provide smooth DC input for the inverter.