Single Inverter Driving Multiple PMSMs via Phase Current Ratio
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Solution Overview
Problem
Conventional methods for driving multiple permanent magnet synchronous motors (PMSMs) with a single inverter face challenges due to differences in speed and rotor position, requiring multiple current sensors and unable to generate varying voltage levels needed by motors with different parameters and loads.
Innovation Solution
A motor driving apparatus with a power conversion apparatus and control system that adjusts phase current ratios for multiple motors using a single inverter, reducing the number of current sensors needed by connecting motors in a specific configuration and using a DC link with a neutral point to generate the required voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple current sensors are used to monitor each motor in a conventional parallel structure, then measurement precision of current for each motor is improved, but device complexity and cost increase due to requiring 2N current sensors for N motors
Solution Approach 1:
The patent combines current measurement for multiple motors into a single measurement point at the inverter output. By measuring the total current after the inverter and using control algorithms to distribute this current among multiple motors based on their individual requirements, the system achieves accurate current monitoring for each motor without requiring separate sensors for each motor phase.
Solution Approach 2:
A single current sensor at the inverter output serves multiple functions: it measures the total current supplied to all motors, enables calculation of individual motor currents through control algorithms, and provides feedback for adjusting voltage levels and current ratios for each motor. This universal measurement approach replaces the need for multiple dedicated sensors.
2Device complexity
If a single inverter is used to drive multiple PMSMs with different parameters and loads, then device complexity is reduced, but the ability to generate various voltage levels required by different motors is lost
Solution Approach 1:
The patent implements dynamic voltage and current ratio adjustment for each motor phase. The control system continuously monitors motor parameters, load conditions, and rotor positions, then dynamically adjusts the voltage levels and current ratios supplied to each motor through the single inverter. This dynamic adaptation allows the inverter to provide customized voltage levels to multiple motors with different requirements.
Solution Approach 2:
The system changes electrical parameters (voltage levels, current ratios, frequency) based on motor-specific requirements. By adjusting these parameters dynamically according to each motor's load, speed, and rotor position, the single inverter can effectively drive multiple motors with different parameters without requiring multiple inverters.
3Device complexity
If the same voltage level is applied to all motors in parallel, then device complexity is reduced, but motor performance deteriorates when motors have different parameters and loads
Solution Approach 1:
The patent applies different voltage levels and current ratios to different motor phases based on their specific requirements. Instead of uniform voltage application, the control system tailors the electrical parameters locally to each motor's load, speed, and rotor position conditions, ensuring optimal performance for each motor while using a single inverter.
Solution Approach 2:
The system dynamically adjusts voltage levels and current ratios for each motor based on real-time operating conditions. This dynamic parameter adjustment ensures that each motor receives the appropriate voltage level for its current load and speed requirements, maintaining reliable performance across all motors with different parameters.
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
Enables efficient driving of multiple PMSMs with different parameters and loads using a single inverter, minimizing current sensors and maintaining motor performance by adjusting current ratios and voltage levels according to each motor's requirements.
Implementation Method 1
a single inverter configured to convert DC power of the DC link to Alternating Current (AC) power required by the plurality of motors
Implementation Method 2
a power conversion apparatus configured to supply power to a plurality of motors
Data Source
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AI summary
A motor driving apparatus and a method of driving a plurality of permanent magnet synchronous motor (PMSM) using a single inverter is described. The motor driving apparatus includes a single power conversion apparatus configured to supply power to a plurality of motors and a control apparatus configured to control the power conversion apparatus to adjust a phase current ratio supplied to the plurality of motors from the single power conversion apparatus according to a requirement of each of the plurality of motors.