DC-DC Converter Loss Estimation via Auto-Zero Circuit
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Solution Overview
Problem
Existing DC-DC converters lack an effective method to measure losses, which hinders the implementation of power reduction methods to maximize efficiency, as traditional methods require additional sensors, incur power loss, or are limited by noise and measurement errors.
Innovation Solution
The implementation of an auto-zero circuit within the feedback loop of the control system to estimate power losses using the auto-zero gain value, allowing for efficient mode switching and optimization without direct loss measurement, and employing feedforward control to achieve zero steady-state error and robust compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If input current sensing is employed to measure converter efficiency, then efficiency measurement capability is improved, but additional sensors are required and power loss increases
Solution Approach 1:
The patent uses an intermediary approach by measuring the output current and using it as a proxy to estimate input current and converter losses. Instead of directly sensing the input current, the system measures output current and combines it with duty cycle information to calculate equivalent input current, thereby avoiding the need for additional input current sensors and reducing power loss.
Solution Approach 2:
The patent replaces direct electrical current sensing with a computational approach. Instead of using physical current sensors to measure input current, the system substitutes mechanical/electrical measurement with mathematical calculation based on output current measurements and duty cycle data, eliminating the need for additional sensing hardware.
2Loss of energy
If duty cycle minimization is employed to reduce power loss, then switching losses are reduced, but measurement noise increases and absolute power estimation becomes inaccurate
Solution Approach 1:
The patent implements feedback by continuously monitoring output current and duty cycle, then using this information to calculate and adjust the estimated power losses. The system feeds back the calculated losses to the control algorithm, which uses this information to make informed decisions about mode switching and operation optimization, thereby improving measurement accuracy while maintaining low switching losses.
Solution Approach 2:
The patent changes the measurement parameters from direct input current sensing to a combination of output current and duty cycle measurements. By transforming the measurement approach and using calculated parameters instead of direct sensing, the system achieves accurate power loss estimation without the noise and accuracy problems associated with direct duty cycle measurement.
3Ease of operation
If predefined set points are used for mode switching, then implementation simplicity is improved, but efficiency optimization is limited due to estimation errors
Solution Approach 1:
The patent transitions from static predefined set points to dynamic mode switching thresholds. Instead of using fixed current thresholds for switching between single-phase and dual-phase modes, the system dynamically calculates the optimal switching point based on real-time measurements of output current and duty cycle, and the calculated power losses in each mode. This allows the switching thresholds to adapt to changing operating conditions, improving efficiency optimization while maintaining implementation simplicity.
Data Source
AI summary
The present application provides a method of calculating DC-DC converter power losses without the requirement for a measurement of input current. The application also describes the use of such a calculation to determine the optimum point for switchover between a single phase mode or dual phase mode in a two phase DC-DC power supply.