PWMfree

PWMfree is a term used in power electronics to describe techniques for regulating electrical power without relying on traditional pulse-width modulation. It encompasses a family of approaches that seek to produce a desired average output without the discrete switching pattern of PWM, aiming to reduce switching losses, EMI, and filtering requirements while maintaining control precision.

The concept emerged in discussions about alternatives to PWM for motor drives, power supplies, and audio amplifiers. Rather than varying the width of switching pulses, PWMfree approaches aim to shape the output using continuous-time regulation, high-frequency shaping, sigma-delta modulation, or high-resolution digital control to approximate an intended waveform.

Among the proposed methods are linear or quasi-linear regulators that operate in a continuous-time regime, digital controllers with oversampled frames and dithering, and hybrid techniques that combine small, fast changes with slower, large-scale adjustments. The goal is to achieve smooth output with reduced audible or radiated noise and potentially simpler output filtering.

Applications include motor control, LED drivers, and precision power supplies where EMI or audible noise from PWM is a concern. Performance considerations include trade-offs between response speed, efficiency, and complexity; in some operating regions PWMfree may be less efficient than PWM at high loads or with certain topologies.

Critics note that eliminating PWM can require more complex control algorithms and tighter component tolerances; practical adoption depends on gains in EMI, noise, or system simplicity outweighing added design challenges.

Related topics include pulse-width modulation, linear regulation, and modulation techniques such as sigma-delta and hysteretic control.