Shared Current Sensing Across Inverter Legs for Multi-Motor Drives
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Solution Overview
Problem
In multi-inverter and multi-motor systems, the large number of current sense devices required for accurate current measurements increases circuit complexity, costs, and power losses, necessitating a more efficient and cost-effective solution for current sensing.
Innovation Solution
A current sensor is shared by at least two inverter legs from different inverters, allowing for precise current measurement across multiple phases while reducing the number of devices needed, thereby minimizing space, cost, and power losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current sense devices are used for each phase winding in multi-inverter and multi-motor system, then accurate current measurements are achieved, but device complexity and cost increase
Solution Approach 1:
A single current sense device is designed to serve multiple inverter legs across different inverters simultaneously. The device measures currents from multiple phases by sequentially connecting to different inverter legs through switching mechanisms, enabling one device to perform the function of multiple devices would otherwise be required in a multi-inverter multi-motor system
Solution Approach 2:
The patent combines multiple current measurement functions into a single current sense device. By merging the measurement capabilities for multiple phases and multiple inverters into one device, the system reduces the total number of current sense devices required, thereby simplifying the circuit and reducing complexity while maintaining accurate current measurement across all phases
2Measurement precision
If multiple current sense devices are deployed in multi-inverter and multi-motor system, then precise current measurements are obtained, but power losses increase
Solution Approach 1:
The current sense device is designed with multi-functional capability to measure currents across multiple inverter legs sequentially. By using one device for multiple measurement tasks instead of dedicating separate devices to each leg, the total power consumption and associated losses are reduced while maintaining the ability to accurately measure all phase currents
3Measurement precision
If current sense devices are added to each inverter leg, then accurate current sensing is achieved, but space occupation increases
Solution Approach 1:
The patent merges multiple current sensing functions into a single physical device. Instead of placing separate current sense devices at each inverter leg location, one consolidated device is used that can sequentially connect to and measure currents from multiple inverter legs, significantly reducing the space required for current sensing components in the multi-inverter multi-motor system
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 approach effectively reduces the number of current sense devices required, lowering costs and space usage while maintaining accurate current measurement capabilities, thereby simplifying the system and reducing power losses.
Implementation Method 1
The voltage drop across the resistor is used to determine the current flowing through the phase winding
Data Source
AI summary
An apparatus includes a first inverter configured to drive a first motor having a plurality of phases, the first inverter comprising a plurality of inverter legs, each of which is coupled to a corresponding phase of the first motor, a second inverter configured to drive a second motor having a plurality of phases, the second inverter comprising a plurality of inverter legs, each of which is coupled to a corresponding phase of the second motor, and a first current sensor configured to sense currents flowing in the first inverter and the second inverter, wherein the first current sensor is shared by at least by two inverter legs.