Integrated DC Choke for Parallel Motor Drives
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Solution Overview
Problem
Power conversion systems, particularly motor drives, face issues with common mode voltage stresses and harmonics, leading to degradation and potential damage to motor loads, and existing solutions require transformers which increase size, weight, and cost.
Innovation Solution
A power conversion system utilizing multiple rectifiers and inverters with a shared common mode choke, where the rectifier inputs and inverter outputs are coupled, and a single choke is used to connect the rectifier DC outputs to the inverter DC inputs, with synchronized switching control signals to mitigate common mode voltage stresses and reduce system size, weight, and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transformers are used to mitigate common mode voltage stresses, then motor protection is improved, but system size, weight, and cost increase
Solution Approach 1:
The patent extracts the common mode choke function from the transformer-based solution and implements it as a separate, dedicated component in the DC link. This allows achieving motor protection through common mode voltage control without requiring heavy transformers, thereby reducing system weight while maintaining reliability
Solution Approach 2:
The patent changes the approach from voltage transformation (transformers) to common mode voltage control (DC link choke). By controlling the common mode voltage parameters through the choke and coordinated switching, the system achieves motor protection without the weight penalty of transformers
2Reliability
If transformers are used to mitigate common mode voltage stresses, then motor protection is improved, but system cost increases
Solution Approach 1:
The patent extracts the common mode choke function from the transformer-based solution and implements it as a separate, dedicated component in the DC link. This allows achieving motor protection without requiring expensive transformers, thereby reducing system cost while maintaining reliability
Solution Approach 2:
The patent replaces expensive transformers with a more cost-effective DC link choke configuration combined with coordinated switching control. This cheaper solution achieves the same motor protection function without the high cost of transformer components
3Power
If separate motor drives are connected in parallel to increase drive capability, then power output is improved, but system size and weight increase
Solution Approach 1:
The patent merges multiple rectifier-inverter units into a single integrated system sharing a common DC link and common mode choke. This consolidation achieves increased drive capability through parallel operation while sharing common components, thereby reducing overall system weight compared to separate drives
Solution Approach 2:
The common mode choke serves multiple functions: it controls common mode voltages for motor protection, provides DC link inductance for multiple rectifier-inverter units, and enables coordinated switching operation. This multi-functionality reduces the need for separate components in each drive unit, reducing overall system weight
4Power
If separate motor drives are connected in parallel to increase drive capability, then power output is improved, but system size increases
Solution Approach 1:
The patent merges multiple rectifier-inverter units into a single integrated system sharing a common DC link and common mode choke. This consolidation achieves increased drive capability through parallel operation while sharing common components, thereby reducing overall system size compared to separate drives
Solution Approach 2:
The common mode choke serves multiple functions: it controls common mode voltages for motor protection, provides DC link inductance for multiple rectifier-inverter units, and enables coordinated switching operation. This multi-functionality reduces the need for separate components in each drive unit, reducing overall system size
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 configuration effectively reduces common mode voltage stresses, minimizes the need for transformers, and enhances drive capability while reducing the overall size, weight, and cost of the power conversion system compared to parallel connections of separate drives.
Implementation Method 1
a single choke is provided, including one or more coils coupled between the first rectifier DC output and the first inverter DC input, as well as one or more further coils coupled between the second rectifier DC output and the second inverter DC input
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A power conversion system with multiple parallel connected motor drives including a plurality of rectifiers and a corresponding inverters connected by windings of a single common mode choke.