Integrated Motor Drive Charger With Isolated Multilevel Conversion
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Solution Overview
Problem
Current on-board battery chargers for electric vehicles face challenges in integrating with motor drive units, leading to increased size and weight, and inefficiencies in power conversion, which affect the performance and reliability of electric vehicle systems.
Innovation Solution
An integrated motor drive and isolated battery charger system that utilizes a power conversion apparatus with an insulation-type DC-DC circuit, inverter circuits, and control mechanisms to suppress output current changes and reduce high-frequency components, allowing for a downsized smoothing capacitor and efficient power conversion, while also sharing power electronic conversion circuits with the motor drive to minimize space and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If separate motor drive and battery charger systems are used, then functional reliability is maintained, but system size and weight increase
Solution Approach 1:
The patent combines the motor drive unit and battery charger into a single integrated power conversion system. The inverter circuit serves dual purposes: driving the motor during operation and functioning as the charger during charging mode. This merging eliminates the need for separate charger hardware, reducing overall system weight and size while maintaining functional reliability through unified control architecture
Solution Approach 2:
The inverter circuit is designed with multi-functionality, capable of operating in both motor drive mode and battery charging mode. The same power electronic components and control system perform different functions based on operational requirements, thereby eliminating redundant components and reducing system weight without compromising the reliability of either function
2Loss of energy
If traditional AC/DC stage with EMI filters and bridge rectifier is used, then EMI compliance is achieved, but power conversion efficiency decreases
Solution Approach 1:
The patent extracts and eliminates the traditional AC/DC stage components including EMI filters and bridge rectifier from the power conversion system. By removing these components that cause energy losses, the system achieves higher power conversion efficiency while managing EMI through alternative means in the integrated architecture
Solution Approach 2:
The patent replaces the traditional mechanical/electrical power conversion architecture (with physical EMI filters and rectifier circuits) with a controlled power electronics-based AC/DC conversion system. The AC/DC conversion is achieved through coordinated switching of the inverter circuit, eliminating the need for separate EMI filtering hardware and reducing power conversion losses
3Stability of the object's composition
If large smoothing capacitor is used, then output current stability is improved, but device size and cost increase
Solution Approach 1:
The patent implements a control mechanism that monitors the output current of the inverter circuit and adjusts the driving of the DC/DC circuit accordingly. This feedback control stabilizes the output current by compensating for variations, eliminating the need for large smoothing capacitors and thereby reducing device volume and cost
4Volume of stationary object
If integrated motor drive and charger system is used, then system size and weight are reduced, but control complexity increases
Solution Approach 1:
The control system is designed with universality, using the same control architecture to manage both motor drive and battery charging functions. The control circuit identifies operational mode and adjusts parameters accordingly, reducing the need for separate control circuits and thereby limiting the increase in control complexity despite the integrated design
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 solution enables a compact, high-efficiency power conversion system that reduces the capacitance of smoothing capacitors, enhances power factor correction, and integrates motor drive and charging functions, improving the performance and reliability of electric vehicle systems by minimizing size, weight, and harmonic content.
Implementation Method 1
an insulation-type DC-DC circuit for converting a voltage supplied from a DC power supply
Implementation Method 2
an inverter circuit for converting an output voltage of the DC-DC circuit into an AC voltage
Data Source
Figure 1~2
Figure 3A
Figure 3B
AI summary
A system includes a first power conversion device connected to a first power source, a first isolated power conversion device connected to the first power source, and a second power conversion device connected to the first isolated power conversion device, wherein outputs of the first power conversion device and outputs of the second power conversion device are connected in series, and series-connected outputs of the first power conversion device and the second power conversion device are configured to drive a motor.