Single-Phase Full-Bridge Inverter with Bipolar PWM Modulation

Single-phase full-bridge inverter with bipolar PWM modulation is a widely adopted power electronics conversion technology for DC-to-AC transformation. This technique employs specific modulation schemes to achieve precise output voltage control, making it suitable for applications like variable-frequency drives, uninterruptible power supplies (UPS), and renewable energy systems. From a code implementation perspective, the PWM generation algorithm typically involves comparing a high-frequency carrier wave (triangular/sawtooth) with a modulating signal (sine wave) to produce switching pulses.

In bipolar PWM modulation, the two switching devices in each bridge leg operate in complementary states, causing the output voltage to alternate between positive and negative DC bus voltages. This modulation strategy effectively reduces harmonic content and enhances output voltage quality. Code implementation involves dynamically adjusting the PWM duty cycle to control AC output voltage amplitude, while modifying the carrier frequency impacts waveform smoothness—typically implemented through microcontroller timer modules and interrupt service routines.

The single-phase full-bridge inverter comprises four switching devices (commonly IGBTs or MOSFETs) in an H-bridge configuration. Bipolar PWM modulation enables simultaneous switching of diagonal transistor pairs, generating alternating voltage across the load. Compared to unipolar modulation, this approach features simpler control logic—often implemented through basic XOR operations or complementary PWM channel assignments in MCUs. However, higher switching losses necessitate trade-offs between efficiency and output performance, requiring thermal management algorithms in practical implementations.

Key advantages include excellent dynamic response, low harmonic distortion, and strong noise immunity. Design considerations must address switching losses and electromagnetic interference (EMI), typically mitigated through integrated filtering circuits and software-based dead-time insertion algorithms to prevent shoot-through currents. System optimization often involves implementing PID controllers for voltage regulation and FFT-based harmonic analysis routines for performance monitoring.