Bipolar Pulse Modulation in Switching Amplifiers With Lower Switching Loss
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Solution Overview
Problem
Existing switching amplifiers suffer from substantial switching power losses due to high switching rates, particularly in high peak-to-average-power-ratio signals, leading to low long-term average efficiency and short operating lifetimes in battery-powered applications.
Innovation Solution
A novel pulse frequency modulation (PFM) system using bipolar pulses, known as bipolar PFM (BPFM), which employs controllable positive and negative pulses with independent frequencies, combined with quasi-resonant conversion (QRC) to minimize switching losses and electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PWM is used with high switching rate, then signal fidelity is improved, but switching power losses increase
Solution Approach 1:
The patent applies dynamics by making the switching frequency variable rather than fixed. The switching frequency is dynamically adjusted based on the input signal amplitude - higher frequencies are used when the signal amplitude is large to maintain signal fidelity, while lower frequencies are used when the signal amplitude is small to reduce switching power losses. This dynamic adaptation resolves the contradiction between maintaining signal fidelity and minimizing energy loss.
2Measurement precision
If SDM is used to generate on-off switching pattern, then signal resolution is improved, but switching rate increases causing higher power losses
Solution Approach 1:
The patent applies parameter changes by modifying the switching frequency parameter based on signal conditions. Instead of using a fixed high switching rate as in traditional SDM, the switching frequency is changed dynamically according to the input signal amplitude. This parameter adaptation maintains the signal resolution benefits of SDM while reducing the switching power losses that occur at excessively high frequencies.
3Loss of energy
If QRC is used to reduce per-pulse switching energy loss, then efficiency is improved, but switching rate increases outweighing the benefits
Solution Approach 1:
The patent applies dynamics by making the switching frequency variable rather than fixed. The switching frequency is dynamically adjusted based on the input signal amplitude - higher frequencies are used when the signal amplitude is large to maintain signal fidelity, while lower frequencies are used when the signal amplitude is small to reduce switching power losses. This dynamic adaptation resolves the contradiction between maintaining signal fidelity and minimizing energy loss.
4Measurement precision
If high switching rate is used, then signal accuracy is improved, but long-term average efficiency decreases
Solution Approach 1:
The patent applies parameter changes by modifying the switching frequency parameter based on signal conditions. Instead of using a fixed high switching rate as in traditional SDM, the switching frequency is changed dynamically according to the input signal amplitude. This parameter adaptation maintains the signal resolution benefits of SDM while reducing the switching power losses that occur at excessively high frequencies.
Data Source
AI summary
A switching amplifier includes a modulator, which includes a pulse generator. The pulse generator generates positive and negative pulses, in response to an input signal, and the frequency of the negative pulses can be controlled independently of the frequency of the positive pulses. The positive pulses and negative pulses are combined to form a composite pulse stream, which can be low-pass filtered such that the filter output is an amplified version of the input signal.