Dual-Bridge DC/DC Converter Phase Shift Control
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Solution Overview
Problem
Double-bridge DC/DC converters face challenges in maintaining optimal operation as input and output voltages evolve, leading to unequal voltages across the inductive circuit, which results in increased AC current and reduced power factor, with existing solutions like resonant circuits or high reactance inductors being insufficient or limiting power transmission.
Innovation Solution
A control method that determines an optimal phase shift angle between alternating voltages and adjusts the switching frequency to minimize current phase shift, ensuring the current is in phase with one voltage and has minimal phase shift with the other, using a processing unit to implement a main regulation loop and adjust the switching frequency based on calculated optimal phase shift angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resonant circuit is used to maintain optimal operation, then the current phase shift is reduced, but the solution does not achieve optimum operation for all operating points
Solution Approach 1:
The patent implements a dynamic control method that continuously adjusts the phase shift angle between primary and secondary alternating voltages based on real-time operating conditions. The control unit modifies the phase shift angle dynamically to maintain optimal operation across varying input voltages, output voltages, and power levels, resolving the contradiction between maintaining optimal operation and adapting to different operating points.
Solution Approach 2:
The patent changes the phase shift angle parameter dynamically to optimize performance. By adjusting this electrical parameter based on operating conditions rather than using a fixed resonant circuit configuration, the system achieves optimal operation across all operating points including different power levels and voltage conditions.
2Reliability
If a high reactance leakage inductor is used, then the current phase shift is reduced, but the transmissible power is limited and power factor is reduced
Solution Approach 1:
Instead of using a fixed high reactance leakage inductor, the patent dynamically changes the effective phase shift angle parameter through control of the alternating voltage phases. This allows the system to achieve current phase alignment without the power-limiting effects of a fixed high reactance inductor, thereby maintaining both good power factor and high transmissible power capability.
Solution Approach 2:
The patent replaces the passive mechanical/electrical solution of using a high reactance inductor with an active control system that electronically adjusts phase relationships. This substitution eliminates the need for large physical inductors while achieving the same current alignment benefit without power transmission limitations.
3Reliability
If trapezoidal or triangular modulation is used, then the current phase shift is optimized, but additional processing capabilities are required
Solution Approach 1:
The patent implements a feedback control system where the control unit continuously monitors operating conditions and adjusts the phase shift angle accordingly. This feedback mechanism optimizes current phase alignment while using standard processing capabilities, avoiding the need for complex trapezoidal or triangular modulation schemes by employing a more straightforward phase-angle control approach.
4Loss of energy
If the transformer transformation ratio is adjusted to equalize voltages V1 and V2, then the AC current is minimized, but the choice of transformation ratio is fixed and cannot adapt to evolving voltages
Solution Approach 1:
The patent replaces the fixed transformation ratio approach with a dynamic phase shift angle control mechanism. Instead of relying on a fixed transformer ratio that cannot adapt to voltage changes, the system dynamically adjusts the phase relationship between primary and secondary voltages, maintaining optimal current conditions even as input and output voltages evolve during operation.
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5B
AI summary
The invention relates to a method of control used in a processing unit (PU) to control a DC/DC converter with a dual-bridge topology comprising two conversion stages. The said DC/DC converter is controlled by the processing unit (PU) to convert a first DC voltage (Vin) into a second DC voltage (Vout) while using a main regulating circuit (B1). The said method is characterized in that it is adapted to: - Determine an optimal phase angle (ø') from the first DC voltage (Vin) and the second DC voltage (Vout), Determine a switching frequency or act upon the switching frequency to be applied to the switches, in such a way as to make a current phase angle (ø) from the main regulating circuit correspond with the optimal phase angle (ø').