PWM Control Signal Segmentation for Voltage Accuracy
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Solution Overview
Problem
Conventional power systems face challenges in accurately adjusting output voltage due to the minimum pulse-width limitation, leading to output energy distortion and potential damage from surge voltages caused by reverse recovery currents in parasitic diodes.
Innovation Solution
A power system and pulse width modulation method that includes a control unit and pulse width modulation unit, which generates driving signals by dividing control signals into positive and negative periodic signals, clamping thresholds, and adjusting signals based on triangular waveforms to minimize distortion and meet minimum pulse-width limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the minimum pulse-width limitation is applied to ensure reverse recovery current becomes zero, then the reliability of the power system is improved, but the manufacturing precision of the output voltage is deteriorated
Solution Approach 1:
The pulse width modulation unit performs preliminary actions by dividing the control signal into positive and negative periodic signals before the minimum pulse-width limitation period, and pre-calculates the required pulse width adjustments. This allows the system to prepare compensation values in advance, ensuring that when the minimum pulse-width limitation is applied, the output voltage can still be accurately controlled without distortion.
Solution Approach 2:
The invention changes the parameter of pulse width dynamically by adjusting it according to the control signal and the minimum pulse-width limitation requirements. The pulse width modulation unit modifies the pulse width parameters in real-time, increasing the pulse width when needed to meet the minimum limitation while maintaining output voltage accuracy, thus resolving the contradiction between reliability and manufacturing precision.
2Object-affected harmful factors
If the minimum pulse-width limitation is applied to prevent surge voltage, then the object-affected harmful factors are reduced, but the loss of information in output energy is increased
Solution Approach 1:
The pulse width modulation unit uses feedback mechanisms to monitor the control signal and adjust the pulse width accordingly. By comparing the desired output with the actual output during the minimum pulse-width limitation period, the system dynamically adjusts the pulse width to compensate for any energy distortion, thus preventing surge voltage while minimizing information loss in the output energy.
Solution Approach 2:
The system performs preliminary division of the control signal into positive and negative periodic signals, allowing the pulse width modulation unit to pre-determine the appropriate pulse width adjustments before the minimum pulse-width limitation takes effect. This preliminary action ensures that the output energy maintains its intended characteristics while still preventing surge voltage.
3Manufacturing precision
If the control signal is divided into positive and negative periodic signals with pulse width adjustment, then the manufacturing precision of output voltage is improved, but the device complexity is increased
Solution Approach 1:
The control signal is segmented into positive and negative periodic signals, allowing independent processing and adjustment of each segment. This segmentation enables the pulse width modulation unit to apply different pulse width adjustments to different parts of the control signal, improving output voltage accuracy while managing device complexity through modular signal processing.
Data Source
AI summary
A power system includes a pulse width modulation device. The pulse width modulation device outputs first, second, third and fourth driving signals. The pulse width modulation device receives a control signal. The control signal is divided into a positive periodic signal and a negative periodic signal. A portion of the positive periodic signal higher than or equal to a maximum threshold voltage is clamped as the maximum threshold voltage to generate a first comparison waveform. The positive periodic signal is clamped as the reference voltage level to generate a second comparison waveform. According to the first comparison waveform, a first ramp signal is generated. According to the second comparison waveform, a first pulse width modulation signal is generated. The first, second, third and fourth driving signals are adjusted according to the first ramp signal and the first pulse width modulation signal.