Modular DC-DC Converter Circuit for Constant Boost Under Switch Failure
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Solution Overview
Problem
Existing non-isolated high-order DC-DC converters face challenges with complex configurations, high electrical losses, large component size, reduced compactness, and reliability issues due to failure of control switches, which affect their efficiency and operational stability.
Innovation Solution
A DC-DC converter design comprising multiple DC voltage converter circuits connected in series and parallel, with parallel control diodes and a control circuit that maintains a constant boost factor K even when one or more control switches fail, using a proportional integral (PI) algorithm to adjust the control signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If non-isolated high-order DC-DC converters are used to achieve high conversion ratio, then the voltage step-up capability is improved, but the circuit complexity and control difficulty increase significantly
Solution Approach 1:
The converter is divided into multiple identical modular units (first converter unit, second converter unit, third converter unit, fourth converter unit), each containing the basic components (inductor, switch, diode, capacitor). This segmentation allows the system to achieve high conversion ratio through modular cascading while simplifying the design and control of each individual unit.
Solution Approach 2:
Multiple converter units are merged in a specific configuration where their outputs are combined to achieve the overall voltage step-up function. The parallel connection of diodes and coordinated switching of multiple units merges their individual contributions to produce the high conversion ratio effect without requiring each unit to be overly complex.
2Ease of operation
If low switching frequency is used to control the switches, then the control simplicity is improved, but the inductor size increases and compactness is reduced
Solution Approach 1:
The system uses dynamic coordinated switching control where multiple switches (S1, S2, S3, S4) are operated in different phases and sequences. This dynamic switching strategy allows the use of higher switching frequencies while maintaining control simplicity through standardized control signals, thereby reducing inductor size without sacrificing ease of operation.
Solution Approach 2:
The converter employs periodic switching cycles with specific duty ratios for each switch within a switching period. This periodic action enables high-frequency operation with simplified control logic, as each switch follows a repeating pattern that can be generated by standard PWM controllers, thus reducing component size while maintaining operational simplicity.
3Power
If cascaded booster circuits are used to achieve high boost ratio, then the voltage multiplication is improved, but the reliability decreases when capacitor or control switch fails
Solution Approach 1:
The circuit incorporates parallel diodes (D1 parallel with C1, D2 parallel with C2, etc.) as protective elements connected across each converter unit's capacitor. These diodes provide alternative current paths in advance, cushioning against the effects of capacitor or switch failure. When a switch or capacitor fails, the parallel diode allows the unit to continue operating in a degraded mode, maintaining system reliability while preserving the high boost ratio capability through the remaining functional units.
4Measurement precision
If complex control algorithms are used to maintain constant boost factor, then the control precision is improved, but the programming complexity and microcontroller compatibility requirements increase
Solution Approach 1:
The system maintains constant boost factor by dynamically adjusting the duty ratios of multiple switches (S1, S2, S3, S4) in a coordinated manner. By changing the timing parameters and duty cycles of these switches according to predetermined relationships, the system achieves precise control of the overall conversion ratio. This parameter-based control approach simplifies programming compared to complex algorithms, as it relies on standard PWM control techniques that are widely supported by microcontrollers.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design ensures a constant conversion ratio and control range, reduces losses, and maintains operational efficiency even when control switches fail, enhancing reliability and adaptability.
Implementation Method 1
The circuit operates on the principle of storing energy in the form of a magnetic field in an inductor
Implementation Method 2
The circuit operates on the principle of storing energy in the form of a magnetic field in an inductor and an electric field in a capacitor
Data Source
AI summary
The invention discloses a DC-DC voltage converter, which includes: i) a plurality of DC voltage converter circuits connected in series and in parallel, wherein each DC voltage converter circuit includes an inductor, a control switch, a diode, and a capacitor; and a plurality of control diodes arranged in parallel with the capacitor in the DC voltage converter circuit, wherein the number of diodes ND=2N−1 where N is the number of DC voltage converter circuits and N is a positive integer; and ii) a control circuit coupled to the control switch to operate the voltage converter when one or more control switches in the DC voltage converter circuit fail; and adjusting the conversion factor (boost factor) to always be a constant k.