Time-Based Boost DC-DC Converter Control for RHP Zero Mitigation
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Solution Overview
Problem
The maximum achievable bandwidth of boost DC-DC converters is limited by the presence of a Right-Half-Plane (RHP) zero, which restricts the use of time-based control loops due to increased area occupation and power consumption.
Innovation Solution
The introduction of a time-based control loop that performs a voltage-to-time conversion of the voltage error, using an integral and proportional branch with current-controlled oscillators and delay lines, and injecting the AC component of the inductor current to compensate for the DC part, effectively mitigates the RHP zero.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a time-based control loop is used in boost DC-DC converter, then bandwidth and switching frequency are improved, but area occupation and power consumption increase due to RHP zero compensation requirements
Solution Approach 1:
The control loop is segmented into two independent paths: a proportional path handling AC components and an integral path handling DC components. This segmentation allows each path to be optimized independently, with the proportional path using delay lines for AC compensation and the integral path using integrators for DC regulation, thereby reducing the overall area requirement while maintaining high bandwidth performance
Solution Approach 2:
The patent transitions from traditional voltage-based control to time-based control by introducing delay lines that operate in the time domain. This dimensional change from voltage to time allows the system to achieve higher bandwidth without proportionally increasing area, as time-based operations can be implemented with smaller, faster circuit elements
2Productivity
If a time-based control loop is used in boost DC-DC converter, then bandwidth and switching frequency are improved, but power consumption increases due to RHP zero compensation requirements
Solution Approach 1:
By segmenting the control loop into proportional and integral paths, each with dedicated compensation mechanisms, the system avoids the need for high-gain amplifiers that would consume excessive power. The proportional path uses delay lines with minimal power consumption for AC compensation, while the integral path handles DC regulation efficiently, collectively reducing overall power consumption while maintaining high bandwidth
Solution Approach 2:
The patent replaces traditional voltage-based compensation mechanisms with time-based delay lines and phase detectors. This substitution eliminates the need for high-power operational amplifiers and complex compensation networks, achieving the same bandwidth enhancement with significantly lower power consumption through time-domain signal processing
3Area of stationary object
If voltage-based control loop is used, then area occupation is reduced, but bandwidth is limited and error-Amplifier power consumption increases at high frequencies
Solution Approach 1:
The patent transitions from voltage-based control to time-based control by introducing delay lines that operate in the time domain. This dimensional change allows the system to achieve higher bandwidth without proportionally increasing area, as time-based operations can be implemented with smaller, faster circuit elements that consume less power at high frequencies
4Productivity
If delay lines with large gains are used to compensate RHP zero in time-based implementation, then bandwidth is improved, but area occupation and power consumption increase
Solution Approach 1:
The control loop is segmented into proportional and integral paths, allowing AC and DC components to be handled separately. This segmentation eliminates the need for large-gain delay lines, as the proportional path uses moderate-gain delay lines for AC compensation while the integral path handles DC regulation, thereby reducing the area occupation while maintaining high bandwidth performance
Data Source
AI summary
A time based boost DC-DC converter generates an output voltage using an inductor. A voltage error between the output voltage and a reference voltage is determined and processed in a) an integral control branch which converts the voltage error into an integral control current signal used to control a current controlled oscillator, and b) a proportional branch which converts the voltage error into a proportional control current signal used to control signal a delay line. Current flowing in the inductor is sensed, attenuated and used to apply adjustment to the integral and proportional control current signals. The output from the current controlled oscillator is passed through the delay line and phase detected in order to generate pulse width modulation (PWM) control signaling driving switch operation in the converter.