Power Converter Slope Parameter Calculation for Low Sampling Frequency
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Solution Overview
Problem
Conventional power converting systems face challenges in achieving high-accuracy current control due to the difficulty in measuring actual inductance and obtaining accurate slope parameters for inductor current, especially at low sampling frequencies, which results in phase lag and increased costs with high sampling frequencies.
Innovation Solution
A driving control device and method that includes an analog/digital converter, a measuring unit, and a control module to automatically calculate the slope parameters of inductor current using equations based on collected data, allowing for high-accuracy digital control at low sampling frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sampling frequency is raised to observe more data and minimize error, then measurement precision is improved, but converting time increases and phase lag increases
Solution Approach 1:
The system performs preliminary calculation of the slope parameter using previously obtained inductor current values and duty cycle information. By pre-calculating the slope parameter based on historical data, the system avoids the need for high-frequency real-time conversion, thus reducing converting time while maintaining measurement precision.
Solution Approach 2:
The patent introduces an intermediate calculation step where the slope parameter is derived as a mediator between raw current measurements and final control decisions. This intermediate parameter encapsulates the essential dynamic characteristics of the inductor current, allowing the system to make accurate control decisions without requiring continuous high-frequency conversions.
2Measurement precision
If sampling frequency is raised to minimize error, then measurement precision is improved, but extra phase lag is caused
Solution Approach 1:
The slope parameter is calculated in advance using previous sampling data before the actual control decision is made. This preliminary calculation allows the system to anticipate current trends without introducing additional phase lag, as the calculation uses historical rather than real-time data.
Solution Approach 2:
The system uses its own historical measurement data to self-determine the slope parameter, eliminating the need for external high-frequency sensing. The controller serves itself by deriving necessary parameters from its existing data resources, thus avoiding the phase lag associated with external high-speed sensing systems.
3Measurement precision
If high sampling frequency analog/digital convertor is used to minimize error, then measurement precision is improved, but cost increases
Solution Approach 1:
Instead of using expensive high-frequency analog/digital converters, the system creates a computational model (slope parameter) that replicates the essential dynamic behavior of the inductor current. This computational copy allows the system to achieve accurate control using lower-frequency, lower-cost hardware.
Solution Approach 2:
The patent transforms the problem from one requiring high-frequency voltage/current measurements to one solved by calculating a derived parameter (slope) from lower-frequency measurements. By changing the measurement parameter from instantaneous voltage/current to a derived slope parameter, the system can use cheaper components while maintaining control accuracy.
4Manufacturing precision
If actual inductance is measured to obtain accurate slope parameter, then manufacturing precision is improved, but measurement difficulty increases
Solution Approach 1:
The system determines the slope parameter using its own operational data (inductor current values and duty cycle information) without requiring external measurement equipment or separate inductance measurement procedures. The controller calculates the slope parameter autonomously from data already available in its operation, eliminating the difficulty of direct inductance measurement.
Solution Approach 2:
Instead of directly measuring the difficult-to-obtain inductance parameter, the system uses an intermediate approach by calculating the slope parameter from easily measurable quantities (current and duty cycle). This intermediate calculation method bypasses the measurement difficulty while achieving the same control objective.
Data Source
AI summary
A driving control device and method for power converting system includes power converting circuit and driving control device. The driving control device has an analog/digital convertor, a measuring device, and a control module. The driving control method is the analog/digital convertor receives a inductor current and the parameters of the inductor current from the measuring device, measures the slope parameter of the inductor current according the parameters from Equation 1 and Equation 2, then calculates a duty cycle parameter from the slope parameter of the inductor current and use the duty cycle parameter to generate pulse control signal to perform driving control.