Multi-Motor Current Sensing with a Shared Phase-Pair Sensor
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Solution Overview
Problem
Existing motor drive systems require multiple current sensors for each motor phase, which can be cumbersome and costly, especially when dealing with multiple motors.
Innovation Solution
A motor drive device that includes a common sensor to detect the total current flowing through a phase pair of two motors, along with individual sensors for each motor phase, allowing for reduced sensor count and enhanced failure detection and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current sensors are provided for each phase of each motor, then accurate current detection is achieved, but the number of sensors increases and system complexity increases
Solution Approach 1:
The patent combines the detection functions for multiple motor phases into a single common sensor that detects the sum of currents. Specifically, one sensor detects the sum of currents from multiple phases, while other sensors detect individual phase currents. This merging approach reduces the total number of sensors needed while maintaining the ability to calculate individual phase currents through computational processing of the sensor data.
2Reliability
If multiple current sensors are used for each motor phase, then reliable current monitoring is achieved, but system cost and complexity increase
Solution Approach 1:
The patent implements a feedback mechanism where the control unit continuously monitors the sensor outputs and calculates individual phase currents based on the sum current from the common sensor and the individual phase currents from other sensors. This feedback loop ensures reliable current monitoring by constantly updating the current state of each phase based on sensor data processing, maintaining system reliability with fewer sensors.
3Device complexity
If a common sensor detects total current for multiple motors, then sensor count is reduced, but individual phase current detection becomes more complex
Solution Approach 1:
The patent introduces a computational intermediary (the control unit) that processes the sensor data to derive individual phase currents. The common sensor provides the sum current as an intermediary measurement, and the control unit uses mathematical processing to extract individual phase current information. This intermediary approach simplifies the physical sensor configuration while handling the measurement complexity through computational means.
Data Source
AI summary
A motor drive device is provided which includes: a first drive unit configured to drive a plurality of first motor phases; a second drive unit configured to drive a plurality of second motor phases; a common sensor configured to detect a total current flowing through a phase pair obtained by selecting one phase from the plurality of first motor phases and one phase from the plurality of second motor phases; at least one first motor phase sensor and at least one second motor phase sensor configured to detect each current flowing through each phase not included in the phase pair among the plurality of first motor phases and the plurality of second motor phases, respectively; and a drive control unit configured to control drive amounts of the first drive unit and the second drive unit for the plurality of first motor phases and the plurality of second motor phases.