Motor Controller Circuit for Bidirectional 12V-48V Energy Flow
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Solution Overview
Problem
Existing circuit assemblies for linking different electrical voltage levels in motor vehicles are complex and costly, particularly due to the need for large and heavy bidirectional DC/DC converters, and require a second switching unit to tap into the first voltage level for bidirectional energy flow.
Innovation Solution
A second switching unit with two series-connected switching elements in an additional switching branch is connected in parallel to the first voltage level, allowing for a simpler structure and bidirectional energy flow, with the first switching unit extended as an asymmetrical half-bridge, comprising four half-bridges arranged on a common carrier, and controlling switching elements to manage energy flow between voltage levels independently of the electric machine's operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bidirectional DC/DC converter is used to link different electrical voltage levels, then bidirectional energy flow between voltage levels is achieved, but the device volume and weight increase significantly
Solution Approach 1:
The patent merges the DC/DC conversion function with the existing motor controller by integrating a second switching unit into the controller's circuit board. The motor controller's power circuit already includes a first switching unit with six switching elements connected to the motor's phase windings. By adding a second switching unit with two switching elements that connects to the motor controller's neutral point, the system achieves bidirectional energy flow between 12V and 48V batteries without requiring a separate, heavy DC/DC converter.
Solution Approach 2:
The motor controller is designed to perform multiple functions: it controls the motor through the first switching unit while simultaneously managing bidirectional energy flow between different voltage levels through the second switching unit. This multi-functionality eliminates the need for dedicated DC/DC conversion hardware, reducing overall system weight and complexity.
2Adaptability or versatility
If a second switching unit is added to enable bidirectional energy flow, then voltage level adaptation is improved, but the circuit complexity increases
Solution Approach 1:
The second switching unit is integrated into the existing motor controller circuit board rather than being implemented as a separate device. The controller's housing and circuit board serve as the mounting structure for both switching units, eliminating the need for additional mounting hardware and reducing overall system complexity.
Solution Approach 2:
The patent utilizes the motor controller's neutral point (zero-potential point) as a common reference for both the first and second switching units. The neutral point connects to the star point of the motor windings and also serves as a connection point for the second switching unit, creating an equipotential reference that simplifies the circuit design and reduces the number of isolation requirements.
3Volume of moving object
If switching elements are arranged in an asymmetrical half-bridge configuration, then space utilization is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent employs dynamic control of the switching elements through control signals that adjust their switching states based on operational requirements. The control unit generates control signals that coordinate the switching of elements in both the first and second switching units, enabling flexible voltage level adaptation and energy flow direction control while maintaining stable operation despite the asymmetrical configuration.
Data Source
AI summary
A circuit assembly for linking different electrical voltage levels in a motor vehicle, comprising: an electric machine containing induction coils in a star circuit connection with a star point; a first switch unit containing switch elements for generating an AC voltage for the electric machine from a DC voltage of a first voltage level; a DC voltage of a second voltage level; and a second switch unit for a bidirectional electrical energy flow between the DC voltage of the first voltage level and the DC voltage of the second voltage level, wherein the second switch unit has two switch elements arranged in series in an auxiliary switch branch, wherein the auxiliary switch branch is connected in parallel to the DC voltage of the first voltage level, and each connection of the switch elements is connected to the star point.