Motor Stator Coil Charging Circuit for Low-AC-Loss Voltage Boosting
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Solution Overview
Problem
The electrical characteristics of stator coils in motors are not optimal for use in boost circuits, leading to increased AC loss due to low inductance, which is necessary for efficient voltage boosting during battery charging.
Innovation Solution
A charging system that connects stator coils in series to increase inductance, using a charging switch to connect one or more stator coils to a power receiving terminal, and incorporates a cooler to manage heat generation, with optional sub-inverter and neutral point switching elements for enhanced control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If stator coils are used as boost circuit inductors, then the charging system can utilize motor components for voltage boosting, but the inductance is insufficient leading to increased AC loss
Solution Approach 1:
The patent combines multiple stator coils in series configuration to achieve higher equivalent inductance. By connecting the first stator coil and second stator coil in series through the neutral point, the total inductance becomes L1 + L2, which sufficiently reduces AC loss while still utilizing the motor's stator coils for boost circuit functionality.
Solution Approach 2:
The patent introduces switching elements that dynamically reconfigure the stator coil connections during charging operation. The switching elements can connect stator coils in series to increase inductance when needed, and can switch between different configurations to optimize performance under varying operating conditions, thereby reducing AC loss dynamically.
2Loss of energy
If multiple stator coils are connected in series to increase inductance, then AC loss is reduced, but the device complexity increases
Solution Approach 1:
The neutral point of the motor's stator coil system serves multiple functions: it is both the electrical neutral point for motor operation and the connection point for series-connecting stator coils in the boost circuit. This multi-functionality eliminates the need for separate connection components, reducing device complexity while achieving series connection for higher inductance.
Solution Approach 2:
The stator coils themselves provide the inductance needed for the boost circuit without requiring external inductors or additional magnetic components. By utilizing the existing stator coil inductance and connecting them in series, the system serves its own inductance requirement, eliminating the need for separate inductor components and reducing overall device complexity.
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
Reduces AC loss during voltage boosting by increasing the inductance of the boost circuit, allowing efficient charging with reduced heat generation and improved torque output.
Implementation Method 1
a power supply having a lower output voltage than the battery by using stator coils of a motor and lower switching elements of an inverter as a boost circuit
Implementation Method 2
incorporates a cooler to manage heat generation
Implementation Method 3
cooler configured to cool the stator coil with a liquid cooling medium
Data Source
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AI summary
A charging system (2; 102; 202) includes: an inverter (10) including a direct current positive end (10p), a direct current negative end (10η), and alternating current ends (14u, 14v, 14w), the direct current positive end (10p) and the direct current negative end (10n) being connected to a battery (60); a motor (20) including N stator coils (21) each having a first end connected to a corresponding one of the alternating current ends (14u, 14v, 14w) and a second end connected to a neutral point (22); a power receiving terminal (40) including a power receiving positive end (40p) and a power receiving negative end (40n), the power receiving negative end (40n) being connected to a battery negative end (60n) of the battery (60); and a charging switch (31; 131) configured to connect the first end of each of one or more and less than N of the stator coils (21) to the power receiving positive end (40p).