In-Vehicle Charging Circuit Using Motor Coils for Low-Loss DC Charging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing in-vehicle charging devices face challenges in efficiently charging a DC power supply using coils of a rotating electrical machine with high power density and small inductance, leading to increased system cost and efficiency losses due to high control frequencies and the need for additional components like inductors and smoothing capacitors.
Innovation Solution
An in-vehicle charging device configuration that includes an AC-DC converter connected to an active decoupling circuit using the inverter and coils of the rotating electrical machine, eliminating the need for additional passive components and allowing for appropriate inductance setting, thereby reducing switching element losses and circuit complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the control frequency of the inverter or DC-DC converter is increased to suppress harmonic current and ripple, then the power conversion performance is improved, but switching element losses increase and system efficiency decreases
Solution Approach 1:
The patent applies preliminary action by adding an inductor between the external AC power supply and the neutral point of the coils before the AC-DC conversion process. This inductor pre-regulates the current waveform, suppressing harmonic currents at the source. As a result, the inverter and DC-DC converter can operate at lower control frequencies while still achieving effective ripple and harmonic suppression, thereby reducing switching element losses and improving overall system efficiency.
2Reliability
If an inductor is added between the external AC power supply and the neutral point of coils to suppress harmonic current, then the power factor correction is improved, but the device complexity and cost increase
Solution Approach 1:
The patent applies universality by designing the inductor to serve multiple functions simultaneously: it suppresses harmonic currents, improves power factor correction, and reduces ripple on the DC-DC converter side. By consolidating these functions into a single component rather than requiring separate circuits for each function, the overall device complexity is minimized while achieving comprehensive power quality improvement.
3Reliability
If a smoothing capacitor with large capacity is used to reduce ripple on the DC-DC converter side, then the power conversion stability is improved, but the device size and cost increase
Solution Approach 1:
The patent applies preliminary action by placing an inductor upstream in the circuit, between the AC power supply and the coil neutral point. This inductor pre-suppresses harmonic currents and reduces the magnitude of ripple generated during AC-DC conversion. Consequently, the smoothing capacitor on the DC-DC converter side requires a smaller capacity to achieve the same level of ripple reduction, thereby decreasing the capacitor size and associated costs while maintaining power conversion stability.
4Reliability
If the control cycle is shortened to enable high-frequency switching for ripple suppression, then the power conversion performance is improved, but the device complexity and cost increase due to high-speed microcomputer requirements
Solution Approach 1:
The patent applies preliminary action by introducing an inductor that passively suppresses harmonic currents and reduces ripple at the source. This passive preprocessing of the current waveform eliminates the need for high-frequency switching control, allowing the system to maintain effective ripple suppression with a longer control cycle. As a result, a standard-speed microcomputer suffices, avoiding the complexity and cost associated with high-speed processing requirements.
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 configuration enhances system efficiency by reducing the need for high control frequencies and additional components, minimizing system cost and size while maintaining power factor improvement and AC-DC conversion performance.
Implementation Method 1
an inverter that converts power between a direct current and an alternating current of multiple phases
Implementation Method 2
an AC-DC converter that converts power between AC power on an external AC power supply side and first DC power
Data Source
AI summary
An in-vehicle charging device charges a vehicle driving device DC power supply including: a rotating electrical machine including coils of multiple phases connected at a neutral point, and serving as a driving power source of a wheel; an inverter converting power between direct and alternating currents of multiple phases; and the DC power supply connected to the inverter, the in-vehicle charging device including: an AC-DC converter converts power between AC power and first DC power; an active decoupling circuit that includes the inverter, the coils of multiple phases, and an output capacitor, and generates second DC power for charging the DC power supply from the first DC power, in which a DC side terminal of the AC-DC converter and a DC side terminal of the inverter are connected without another passive component, and the output capacitor is connected between the neutral point of the coils and a DC negative electrode.