Parallel Low-Voltage Motor Drive Layout for Back-EMF Limits
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-voltage electric motor systems for electric vehicles face inefficiencies and safety concerns due to high voltage requirements, leading to increased losses, insulation challenges, and EMI issues, while low-voltage switches are not capable of handling the necessary voltages for high-speed operation.
Innovation Solution
The electric motor system employs a parallel configuration of low-voltage power electronics and motor elements, with each phase group receiving current independently, utilizing multiple low-voltage power sources and drive modules to reduce losses and enhance redundancy, allowing for efficient operation at lower voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high voltage is used to achieve desired motor top speed and torque, then voltage headroom is sufficient, but power electronics losses increase and efficiency decreases
Solution Approach 1:
The motor system is divided into multiple independent phase groups (e.g., 6 phase groups instead of 3), with each phase group having its own dedicated low-voltage inverter. This segmentation allows the use of lower voltage switches while maintaining the ability to deliver high power through parallel current paths.
Solution Approach 2:
Multiple low-voltage power sources and inverter modules are combined in parallel to collectively deliver the high power required for motor operation. The parallel configuration of multiple phase groups working together achieves the same power output as a single high-voltage system but with reduced losses.
2Speed
If high voltage is used to overcome series coil back emf, then motor speed capability is achieved, but insulation requirements increase and space for conductor copper decreases
Solution Approach 1:
The winding system is segmented into multiple parallel phase groups, each operating at lower voltage. This eliminates the need for high-voltage insulation while maintaining the ability to generate the required back EMF through increased current capacity and parallel paths.
3Power
If high voltage is used to achieve motor performance, then voltage headroom is sufficient, but capacitive coupling to ground increases causing more losses and EMI issues
Solution Approach 1:
The system changes the voltage parameter from high voltage to low voltage operation. By operating each phase group at lower voltage, the capacitive coupling to ground is significantly reduced, thereby minimizing EMI and capacitive losses while maintaining motor performance through parallel current paths.
4Loss of energy
If low voltage switches are used instead of high voltage devices, then efficiency improves and losses reduce, but voltage headroom is insufficient for high speed operation
Solution Approach 1:
Multiple low-voltage inverter modules are merged in parallel to collectively provide the voltage headroom and power capability required for high-speed motor operation. Each module operates independently at low voltage with high efficiency, while their combined output achieves the necessary voltage and power levels.
5Device complexity
If series winding configuration is used to reduce number of inverters, then device count is reduced, but high voltage requirements increase
Solution Approach 1:
The motor system is segmented into multiple independent phase groups, each with its own inverter. This segmentation allows the use of low-voltage inverters instead of requiring a high-voltage inverter, reducing the voltage stress on individual devices while distributing the power handling across multiple units.
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 achieves significant reductions in losses, improved efficiency, and enhanced safety by minimizing high current transmission and utilizing more efficient low-voltage switches, potentially reducing losses by up to 8 times compared to conventional systems.
Implementation Method 1
Each power electronics drive module 150 is operative to activate a different subset of the plurality of motor coil elements 140... each of the plurality of activatable motor coil elements 140 being operative when activated by application of an electric current thereto to apply a magnetic flux across active air gap 115 for creating relative movement between the rotor 130 and stator 120
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
An electric motor system (100), comprising: a motor unit (110) comprising: a first part (120); a second part (130) movable relative to the first part (120); a plurality of spaced activatable motor elements (140) provided on the first part (120), each activatable motor element (140) being operative when activated by application of an electric current thereto for creating relative movement between the first and second parts (120, 130); and a plurality of power electronics drive modules (150), each power electronics drive module (150) being operatively associated with a different subset of the plurality of activatable motor elements (140) and comprising a power converter (155) operative to convert direct current into a periodic current for powering the activatable motor elements (140); and a power supply arrangement (170) comprising: at least one direct current power source (180); and a plurality of n parallel direct current power supply lines (190), each of the parallel direct current power supply lines (190) being operative to transmit direct current from the at least one direct current power sources (180) to a different subset of the plurality of power electronics drive modules (150).