Modular Power Converter With High-Frequency Transformer Stages
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Solution Overview
Problem
Conventional power converters for hydrogen production facilities are bulky, expensive, and difficult to transport and install due to the use of semiconductor switches and transformers that handle high grid input voltages, requiring on-site assembly and specialized labor, and are limited by the availability and cost of high-power semiconductor switches.
Innovation Solution
A power converter design with multiple converter single-phase string arrangements, each comprising an active rectifier portion, DC/DC converter, inverter portion, and passive diode rectifier, using semiconductor switches for flexible control and a compact transformer operating at elevated frequencies, allowing for efficient, cost-effective, and reliable DC power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a common conventional transformer is used to handle high grid input voltages, then the transformer can transform AC grid input power to internal supply AC power, but the transformer becomes extremely bulky and heavy, making the power converter very bulky and difficult to transport
Solution Approach 1:
The patent changes the operating frequency parameter from grid frequency (50/60 Hz) to elevated frequency (e.g., 400 Hz or higher). This parameter change allows the transformer to achieve the same power transformation capability with significantly reduced size and weight, as transformer dimensions are inversely proportional to operating frequency for a given power rating.
Solution Approach 2:
The patent divides the single high-power transformation stage into multiple lower-power stages: active rectification stage, DC-DC conversion stage, and inverted AC stage. Each stage handles a portion of the total power, allowing the use of smaller, lighter transformers in each stage rather than one large transformer handling all power at grid frequency.
2Loss of energy
If semiconductor switches are used in active rectifiers for generating DC output power, then efficiency is improved and control is better, but semiconductor switches are very expensive or not available for very high DC output powers
Solution Approach 1:
The patent segments the high-power rectification task across multiple parallel active rectifier modules, each handling a fraction of the total power. This segmentation allows the use of available, cost-effective semiconductor switches in each module while collectively achieving the required high total output power.
Solution Approach 2:
The patent introduces an intermediate DC-DC conversion stage between the active rectifier and the final output. This intermediary stage allows the active rectifier to operate at lower, more economical power levels where suitable semiconductor switches are available, while the DC-DC converter handles the power scaling to the required output level.
3Power
If conventional transformers handle high total currents at low grid frequency, then the transformer can process the required power, but the transformer becomes extremely bulky and heavy
Solution Approach 1:
The patent changes the frequency parameter from low grid frequency to elevated frequency operation. Since transformer volume is inversely proportional to frequency for a given power and current rating, this parameter change dramatically reduces the required transformer volume while maintaining the same current handling capability.
Solution Approach 2:
The patent divides the high current handling requirement into multiple parallel current paths through modular active rectifier modules. Each module handles a portion of the total current, allowing the use of smaller transformers in each module rather than one large transformer, thereby reducing total volume.
4Reliability
If the power converter is pre-assembled in the factory for testing, then testing can be completed, but partial disassembly is needed for transportation and final assembly at the installation site, causing defects or problems
Solution Approach 1:
The patent designs the power converter as modular active rectifier units that can be independently assembled and tested. These modules can be pre-assembled and tested in the factory, then transported as complete modules and simply connected at the installation site, eliminating the need for partial disassembly and reducing the risk of assembly defects.
5Reliability
If specialized trained staff are used for on-site assembly, then proper assembly can be achieved, but the implementation requires significant effort and specialized labor
Solution Approach 1:
The patent divides the power converter into standardized modular active rectifier units with uniform connection interfaces. This segmentation with standardization allows simple plug-and-play assembly at the installation site, reducing the skill level and training required for assembly personnel while maintaining assembly quality through standardized procedures.
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 reduces the converter's size and weight by two to three times, enabling easy transportation and installation, reduces material costs, and provides flexible control with minimal downtime, suitable for high-power applications like electrolyzer stacks and DC chargers.
Implementation Method 1
an individual active rectifier portion for rectifying single-phase AC input power to intermediate DC power, the active rectifier portion including an active bridge, e.g. a H-bridge, with semiconductor switches
Implementation Method 2
an inverter portion for inverting the intermediate DC power to first intermediate AC power with an elevated frequency, wherein the inverter portion includes an active bridge, e.g. a H-bridge, with semiconductor switches
Implementation Method 3
a transformer for transforming the first intermediate AC power to second intermediate AC power
Implementation Method 4
a passive diode rectifier for rectifying the second intermediate AC power to the output DC power of the converter single-phase string arrangement, wherein the passive diode rectifier includes a diode bridge
Data Source
AI summary
A power converter (100) for converting multi-phase AC grid input power (GIV, GIC) to DC output power. For allowing efficient, cost-effective, easy installable, and reliable power supply to a DC power consumer with high power requirements, it includes at least one phase block (106A, 106B), each having at least two separate converter single-phase string arrangements (1), each of them including an individual active rectifier portion (10), including a H-bridge with semiconductor switches (12), for rectifying single-phase AC input power (SInV, SInC) to intermediate DC power and an individual DC/DC converter (20). The latter includes an inverter portion (30), having a H-bridge with semiconductor switches (32), for inverting the intermediate DC power to first intermediate AC power (PAC1) with an elevated frequency (f1), a transformer (40, 240) for transforming the first intermediate AC power (PAC1) to second intermediate AC power (PAC2, PAC2A, PAC2B), and a passive diode rectifier (50, 150, 250), including a diode bridge (51), for rectifying the second intermediate AC power (PAC2, PAC2A, PAC2B). The disclosure further discloses a hydrogen production facility (200) with an electrolyzer stack (20) and such a power converter (100).