Multiphase PWM Generation With Ratiometric Frequency Scaling
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Solution Overview
Problem
Existing power conversion technologies face challenges in generating multiphase pulse width modulation (PWM) signals that maintain phase relationships over a range of frequencies, requiring significant processing power and struggling with synchronization issues when external synchronization signals vary widely.
Innovation Solution
The implementation of a programmable modulo arithmetic circuit that generates count enable pulses to PWM generation logic, allowing for variable frequency operation while maintaining ratio-metric duty-cycle and phase relationships, and automatic synchronization with external sync signals by varying the clock pulse rate and using a programmable accumulator threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If standard digital PWM signal generation is used, then fixed frequency operation is achieved, but variable frequency operation capability is lost
Solution Approach 1:
The patent changes the fundamental parameter of time base generation by using ratio-metric scaling where PWM parameters (duty cycle, phase offset, period) are scaled proportionally to the output frequency. This allows the system to adapt to variable frequencies while maintaining correct parameter relationships, resolving the contradiction between frequency adaptability and processing complexity
Solution Approach 2:
The patent replaces complex real-time computational systems with a simpler ratio-metric scaling mechanism. Instead of using processors to calculate and update PWM parameters at each cycle, the system uses proportional scaling based on frequency ratio, substituting mechanical/computational complexity with a more elegant mathematical relationship
2Adaptability or versatility
If processor-based PWM generation is used, then flexibility is improved, but processing power and speed requirements increase
Solution Approach 1:
The ratio-metric scaling system is self-regulating and automatically adjusts PWM parameters based on frequency changes without requiring external processor intervention. The system serves itself by maintaining correct parameter relationships through proportional scaling, eliminating the need for high-power processors to perform real-time calculations
3Ease of operation
If synchronization to external signals is implemented, then signal coordination is improved, but reliability decreases due to sync signal variations
Solution Approach 1:
The patent implements feedback mechanisms that monitor the actual PWM output parameters and adjust the scaling factors accordingly. This feedback loop compensates for variations in external sync signals, preventing runaway duty cycles and distorted signals while maintaining synchronization capability, thus resolving the contradiction between ease of operation and reliability
Data Source
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AI summary
Groups of phase shifted PWM signals are generated that maintain their duty-cycle and phase relationships as a function of the period of the PWM signal frequency. The multiphase PWM signals are generated in a ratio-metric fashion so as to greatly simplify and reduce the computational workload for a processor used in a PWM system. The groups of phase shifted PWM signals may also be synchronized with and automatically scaled to match external synchronization signals.