Electrical Machine Unit With Added Inductance for 400V/800V Charging
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Solution Overview
Problem
The existing electrical machine units in vehicles face challenges in charging infrastructure compatibility due to different voltage support levels, with 400 V and 800 V being common, and insufficient inductances leading to high DC input current at low switching frequencies, limiting the ability to efficiently charge batteries across various charging stations.
Innovation Solution
Incorporating an additional inductance connected to the regular phase windings of the electrical machine, allowing for bidirectional power flow and voltage conversion between 400 V and 800 V systems, enabling efficient energy transfer and charging through a power converter that can operate as both a boost and step-up converter, reducing the need for external DC-DC converters and enhancing system compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an electrical machine unit is designed with standard phase windings for 400V or 800V charging, then it can operate at the corresponding voltage level, but it cannot efficiently charge from charging stations with different voltage levels
Solution Approach 1:
The patent applies universality by enabling the electrical machine unit to perform multiple functions: it can operate as a motor, as a generator, and as a bidirectional DC-DC converter. The power converter is designed to handle both motor control and battery charging functions, while the phase windings serve both motor operation and inductance requirements for DC-DC conversion, eliminating the need for separate dedicated components for each function.
Solution Approach 2:
The patent applies dynamics by making the electrical machine unit adaptable to different operating modes and voltage levels. The control system dynamically switches between motor operation, generator operation, and DC-DC converter modes based on the charging requirements and grid conditions. The bidirectional power flow capability allows the system to dynamically adjust power direction and magnitude to match different charging station voltage levels.
2Loss of energy
If the electrical machine unit operates as a DC-DC converter at low switching frequencies, then efficiency is improved, but insufficient inductance leads to high DC input current
Solution Approach 1:
The patent applies universality by using the existing phase windings of the electrical machine for dual purposes: motor operation and providing inductance for DC-DC conversion. This eliminates the need for separate inductors while satisfying the inductance requirements for efficient low-frequency DC-DC operation. The phase windings' inductance is sufficient to limit DC input current when used in the DC-DC converter mode.
Solution Approach 2:
The patent merges the function of separate inductors with the phase windings of the electrical machine. Instead of having dedicated inductance components for DC-DC conversion, the phase windings themselves provide the necessary inductance. This consolidation reduces component count and allows the system to achieve efficient low-frequency operation without requiring additional inductance elements that would increase device complexity.
3Adaptability or versatility
If a bidirectional power converter is integrated into the electrical machine unit for flexible power flow, then charging flexibility is improved, but the device complexity increases
Solution Approach 1:
The patent applies universality by designing the power converter to handle multiple functions: motor control, regenerative braking, and bidirectional DC-DC conversion for battery charging. The same power converter switches and control circuitry are used for all these functions, eliminating the need for separate dedicated converters for each operation mode. This multi-functional design achieves charging flexibility without proportionally increasing device complexity.
Solution Approach 2:
The patent merges the bidirectional DC-DC converter functionality into the existing power converter structure. The power converter that normally handles motor control also performs battery charging and discharging operations. The switching elements and control system are configured to enable bidirectional power flow, combining multiple power management functions into a single integrated unit rather than using separate dedicated converters for each function.
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
This solution allows for flexible charging across different voltage levels, reduces interfering current ripples, and eliminates the need for external access to the neutral point, making the system more efficient and cost-effective by supporting various charging station voltages and improving power quality.
Implementation Method 1
In particular, the additional inductance is designed as an additional winding, to which a magnetic coupling to at least one of the multiple regular phase windings is provided
Data Source
AI summary
An electrical machine unit includes an electrical machine and a power converter, the electrical machine having a plurality of regular phase windings and an additional inductance, the additional inductance being connected to at least one of the plurality of regular phase windings. The power converter includes a plurality of half-bridges, each of which is connected to one of the plurality of regular phase windings of the electrical machine, the electrical machine unit having DC voltage terminals (B+, B−) for connection to an energy storage (150) and DC side switches (180+, 180−), wherein DC side terminals (146+, 146−) of the plurality of half-bridges are each connected to each other and are each connectable to or disconnectable from a respective one of the DC voltage terminals via one of the DC side switches.