Parallel Inverter Motor Layout for Loop Current Balance
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Solution Overview
Problem
Existing electric motor systems require additional reactors to attenuate loop current and eliminate current unbalance, leading to increased size, weight, and cost.
Innovation Solution
The electric motor system includes a direct-current power supply, a power conversion device with series-connected switching elements, and a star-connected electric motor with two coils per phase, allowing for parallel output of alternating-current power to effectively attenuate loop current and balance current distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reactor is added between the two inverters and the motor to attenuate loop current and eliminate current unbalance, then the current balance is improved, but the size and weight of the system increase
Solution Approach 1:
The invention extracts and eliminates the unnecessary reactor component from the system. By reconfiguring the power conversion device to output parallel alternating-current power and utilizing the motor's existing coil structure, the system achieves loop current attenuation and current balance without requiring the additional reactor, thereby reducing system weight and size.
Solution Approach 2:
The invention enables the motor's coils to serve a dual function: both driving the motor and attenuating loop current. By configuring two sets of switching elements to output parallel alternating-current power to the motor's coils, the system uses the motor's own components to achieve current balance, eliminating the need for external reactors.
2Power
If the size of the reactor is increased to handle large current, then the current handling capability is improved, but the size and weight of the system increase
Solution Approach 1:
The invention makes the motor's coils multi-functional by having them serve both as the driving element and as the loop current attenuation element. The parallel alternating-current power output from the two sets of switching elements utilizes the coils' inherent impedance to attenuate loop current, eliminating the need for separate reactor components regardless of current magnitude.
Solution Approach 2:
The invention merges the function of the reactor with the motor's coil structure. By configuring the power conversion device to output parallel alternating-current power that flows through the motor's coils, the system combines the motor's driving function with the loop current attenuation function into a single integrated structure.
3Reliability
If additional components are added to eliminate current unbalance, then the current balance is improved, but the device complexity increases
Solution Approach 1:
The invention segments the power conversion device into two independent sets of switching elements that each output alternating-current power in parallel. This segmentation allows each set to independently control current flow to the motor's coils, achieving current balance through distributed control rather than requiring a complex centralized reactor-based solution.
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 minimizes the necessary system components, reducing the size and weight of the electric motor system while efficiently eliminating current unbalance and loop current, thus enhancing system efficiency and reducing costs.
Implementation Method 1
a power conversion device (16) including a plurality of switching elements (28) and configured to convert a direct-current power output from the direct-current power supply (14) into an alternating-current power by turning on and off the plurality of switching elements (28)
Data Source
AI summary
In an electric motor system, a power conversion device includes, for each phase, two sets each of which includes an upper arm and a lower arm that are connected in series, the two sets being connected in parallel to a direct-current power supply. The electric motor is a star-connected electric motor. The electric motor includes two coils for each phase.