Parallel DC/DC Converter Current Balancing With Auxiliary Voltage Compensation
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Solution Overview
Problem
Existing electrical DC/DC converters, when operated in parallel with fixed modulation parameters, experience unequal current distribution leading to overloading and reduced output power due to passive current distribution influenced by electric and thermal losses and parasitic elements.
Innovation Solution
A method and controller for a converter arrangement that includes auxiliary voltage sources in series with each converter, adjusting compensation voltages to equalize current distribution by sending compensation signals to balance currents across parallel converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If several electrical converters are operated in parallel with fixed modulation parameters, then the available output power is increased, but the current distribution becomes unequal leading to overloading of some converters
Solution Approach 1:
The patent implements a feedback control mechanism where the actual current of each parallel converter is measured and compared with a reference current. Based on the current deviation, compensation values are calculated and applied to adjust the modulation parameters of each converter dynamically. This closed-loop feedback ensures equal current distribution while maintaining high output power capability.
Solution Approach 2:
The patent dynamically changes modulation parameters (such as duty cycle or switching frequency) of each parallel converter based on its actual current measurement. By adapting these parameters in real-time according to the current deviation from the reference value, the system achieves balanced current distribution across all parallel converters, resolving the contradiction between high power output and equal current sharing.
2Ease of operation
If electrical converters are operated in open-loop with fixed modulation parameters, then the operation is simplified, but the current distribution is determined solely by losses and parasitic elements causing unequal loading
Solution Approach 1:
The patent introduces a feedback control loop that measures the actual current of each converter and uses this information to dynamically adjust modulation parameters. This transforms the open-loop simplified operation into a closed-loop system that maintains operational simplicity while achieving reliable current distribution control through automatic compensation based on measured deviations.
3Loss of energy
If parallel converters have different electric and thermal losses, then the current distribution is passively determined by these losses, but this leads to significant deviations in loading and reduced available output power
Solution Approach 1:
The patent compensates for different electric and thermal losses by dynamically adjusting modulation parameters of each converter based on measured current deviations. This parameter adaptation allows the system to overcome the passive current distribution caused by losses and parasitic elements, ensuring equal loading and maximizing the available output power of the parallel converter arrangement.
Data Source
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AI summary
A method for operating a converter arrangement (20) is described. The converter arrangement (20) being configured for converting a first DC bus voltage into a second DC bus voltage and comprising a first electrical converter (22), a second electrical converter (24) being electrically arranged in parallel with the first electrical converter (22), and a first auxiliary voltage source (26) electrically arranged in series with the first electrical converter (22). The method comprises: receiving a first current value (I1) being representative of a first current through the first electrical converter (22); receiving a second current value (I2) being representative of a second current through the second electrical converter (24); determining a difference between the first and second current values (I1, I2); determining a first compensation voltage value (VC1) depending on the difference such that the first current corresponds to the second current when a first compensation voltage corresponding to the first compensation voltage (VC1) is added to the first DC bus voltage applied to the first electrical converter (22) or when the first compensation voltage is added to a first output voltage generated by the first electrical converter (22); and sending a first compensation signal to the first auxiliary voltage source (26), wherein the first auxiliary voltage source (26) is configured to add the first compensation voltage (VC1) to the first DC bus voltage applied to the first electrical converter (22) or, respectively, to the first output voltage generated by the first electrical converter (22) upon receiving the first compensation signal.