Integrated Charger-Motor Circuit With Motor Isolation Switching
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Solution Overview
Problem
Electric vehicle power systems face challenges in achieving universal voltage compatibility, high efficiency under low load conditions, modular design, reliability, and cost-effectiveness, particularly in AC-DC power converters used for charging and motor control.
Innovation Solution
The proposed solution involves a DC to DC converter system with multi-level power converter stages and a resonant converter, connected in parallel with a DC bus and controlled by a processor to manage voltage and power efficiently across different modes (charge and drive) using switches, allowing for flexible voltage conversion and isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a DC to DC converter is connected in parallel with a DC bus to enable voltage conversion for charging and motor control, then voltage compatibility and efficiency are improved, but device complexity increases due to additional components and control circuitry
Solution Approach 1:
The patent combines the charging function and motor control function into a single integrated power conversion system. The DC to DC converter serves dual purposes: charging the battery when connected in parallel mode, and controlling motor voltage when connected in series mode with the DC bus. This merging of functions reduces the need for separate power conversion circuits, thereby managing complexity while achieving voltage compatibility for both charging and motor operation.
Solution Approach 2:
The system dynamically reconfigures the connection topology between the DC to DC converter and DC bus using switching circuitry. The converter can switch between parallel connection (for charging mode) and series connection (for motor control mode), allowing the same hardware to adapt to different operational requirements. This dynamic reconfiguration enables voltage compatibility across modes without requiring duplicate dedicated circuits for each function.
2Reliability
If isolation is implemented between the charger and motor control system to reduce danger and meet safety standards, then reliability and safety are improved, but device complexity increases due to additional isolation components
Solution Approach 1:
The patent merges the isolation function into the existing transformer component of the DC to DC converter rather than adding separate isolation devices. The transformer inherently provides galvanic isolation between the primary (charger) side and secondary (motor control) side, achieving safety requirements while avoiding the need for additional isolation components. This integrated approach maintains reliability through isolation without proportionally increasing device complexity.
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 voltage compatibility, efficiency, and cost-effectiveness by enabling efficient battery charging and motor power delivery across a wide voltage range, reducing component costs and complexity while maintaining high reliability.
Implementation Method 1
The DC to DC converter is a resonant converter having a resonant frequency, the DC to DC converter controlled by a processor to operate in a narrow range about the resonant frequency
Data Source
AI summary
According to one aspect of the present disclosure, there is provided an apparatus that includes a battery, a Direct Current (DC) bus connected to the battery, and a DC to DC converter connected to the battery in parallel with the DC bus. A Motor Control Unit (MCU) is connected between the DC to DC converter and an electric motor. An Alternating Current (AC) port is connected to the electric motor. Switches connect the DC bus and an output of the DC to DC converter in series as an input to the MCU in a drive mode and disconnect the DC bus from the MCU in a charge mode.