Shared-Leg Voltage Source Inverter for High-Speed Multi-Motor Drive
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Solution Overview
Problem
Existing voltage source inverters (VSIs) for electric motors are bulky and costly when used in miniaturized robotics applications, and sharing a single VSI leg among multiple motors limits their maximum speed due to cumulative back-EMF effects.
Innovation Solution
A system with a voltage source inverter circuit that includes multiple inverter legs, where some legs are shared to drive phases of multiple motors, using a commutation control circuit to transform and modulate voltage signals, ensuring positive phase voltages and reducing the number of required legs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a single common VSI leg is shared among multiple motors, then the physical size of the VSI circuit is reduced, but the maximum speed of the motors is limited
Solution Approach 1:
The patent segments the motor phases into two groups: shared phases (connected to common VSI legs) and unshared phases (connected to dedicated VSI legs). This segmentation allows the system to reduce the number of common VSI legs needed while maintaining sufficient voltage control capability for high-speed operation. By not sharing the unshared phases, the patent avoids the speed limitations that would result from sharing all phases.
Solution Approach 2:
The patent applies different connection strategies to different phases of the motors. Shared phases use a common VSI leg configuration to reduce overall circuit size, while unshared phases use dedicated VSI legs to maintain local voltage control quality and avoid speed limitations. This local differentiation resolves the contradiction between size reduction and speed maintenance.
2Reliability
If multiple VSI legs are used to drive each motor phase, then the motor performance is maintained, but the physical size and cost of the VSI circuit increases
Solution Approach 1:
The common VSI legs are designed to serve multiple motors simultaneously, making them universal components that perform multiple functions. Each common VSI leg can drive shared phases of multiple different motors, reducing the total number of VSI legs needed while maintaining motor performance. This multi-functionality resolves the contradiction between maintaining performance and reducing circuit size.
Solution Approach 2:
The patent merges the control of shared phases from multiple motors into a single common VSI leg, combining multiple functions into one component. This merging reduces the total number of VSI legs required while maintaining the ability to drive multiple motors at full performance, thus resolving the contradiction between motor performance and circuit size.
3Volume of moving object
If a single common VSI leg is shared among multiple motors, then the VSI circuit becomes more compact, but the circuit becomes more susceptible to commutation errors
Solution Approach 1:
By segmenting phases into shared and unshared categories, the patent isolates the potential commutation errors to only the shared phases. The unshared phases with dedicated VSI legs remain immune to commutation errors affecting other motors, thus maintaining overall system reliability while still achieving circuit compactness through the shared phases.
Solution Approach 2:
The patent applies different reliability strategies to different phases: shared phases accept the potential for commutation errors but benefit from size reduction, while unshared phases maintain high reliability through dedicated VSI legs. This local quality differentiation resolves the contradiction between compactness and robustness.
Data Source
AI summary
A system includes a first motor, a second motor, and a third motor, each respective motor comprising three phases. The system further includes a voltage source inverter circuit comprising multiple respective inverter legs. Each respective inverter leg coupled to drive at least one phase of at least one of the respective motors, with a first shared inverter leg coupled to drive a third phase of the first motor and drive a first phase of the second motor. A second shared inverter leg is coupled to drive a third phase of the second motor and a first phase of the third motor.