Compressor Motor Winding Switching to Cut Conduction Loss
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Solution Overview
Problem
Existing motor control devices for compressors face efficiency reduction due to conduction loss and reliability issues, particularly when using semiconductor switches for winding changeover in high-speed and low-speed operations.
Innovation Solution
A motor control device with bidirectional switches made of semiconductor devices, such as triacs or reverse blocking IGBT elements, that switch the number of turns of three-phase motor windings to manage conduction loss and enhance reliability by reducing the number of semiconductor devices through which current flows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a mechanical switch is used as a winding changeover unit, then the structure is simple, but structural wear and deterioration occur at the contact and movable part, making it difficult to obtain higher reliability
Solution Approach 1:
The patent replaces the mechanical switch with a semiconductor switch (specifically a triac or IGBT element) to eliminate mechanical wear and deterioration. The semiconductor switch performs the same winding changeover function without moving parts, thereby significantly improving reliability and durability while maintaining structural simplicity.
2Reliability
If a semiconductor switch is used as the winding changeover unit, then reliability is improved, but it is necessary to combine semiconductor devices such as a diode bridge and transistor, causing large conduction loss
Solution Approach 1:
The patent merges the functions of multiple semiconductor devices into a single triac or IGBT element. The bidirectional switch integrates switching and current handling capabilities that previously required separate diode bridges and transistors, thereby reducing the number of devices and minimizing conduction loss while maintaining high reliability.
Solution Approach 2:
The triac or IGBT element serves multiple functions simultaneously: it acts as a bidirectional switch, handles current in both directions, and performs winding changeover. This multi-functionality eliminates the need for separate diode bridges and transistors, reducing conduction loss while improving reliability.
3Speed
If the number of turns of stator winding is reduced to suppress voltage induced by inverter, then field-weakening control becomes possible at high-speed rotation, but the current required to obtain equivalent torque increases and efficiency at low-speed rotation deteriorates
Solution Approach 1:
The patent implements dynamic switching between different winding configurations (high turn and low turn) based on the motor's operating speed. The bidirectional switch enables real-time reconfiguration of the stator windings, allowing the system to adapt to varying speed requirements and maintain high efficiency across the entire operating range, from low-speed to high-speed rotation.
Solution Approach 2:
The patent changes the electrical parameters of the motor by switching between different numbers of stator winding turns. At low-speed rotation, the high turn configuration provides higher efficiency, while at high-speed rotation, the low turn configuration enables field-weakening control. The bidirectional switch facilitates this parameter change dynamically, optimizing efficiency at each operating point.
4Productivity
If an external switch is connected to switch between high turn and low turn configurations, then high efficiency is achieved in wide operation range, but the device complexity increases
Solution Approach 1:
The patent replaces complex mechanical switching mechanisms with a solid-state bidirectional switch (triac or IGBT element). This substitution maintains the ability to switch between high turn and low turn configurations for wide operation range efficiency, while significantly simplifying the device structure by eliminating mechanical components and reducing the number of separate semiconductor devices required.
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
The solution effectively suppresses efficiency reduction caused by conduction loss while achieving high reliability by optimizing the switching of motor windings and minimizing semiconductor device usage, thereby improving durability and operational efficiency across a wide range of speeds.
Implementation Method 1
a low turn side switch connected between a first neutral point of the three-phase motor and a low turn side connection point of at least two of the three motor windings; and a high turn side switch connected between a second neutral point of the three-phase motor and a high turn side connection point of at least two of the three motor windings
Implementation Method 2
In the permanent magnet synchronous motor, an induced voltage (counter electromotive force) proportional to the number of turns of the stator winding × the rotational speed of the motor is generated
Data Source
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AI summary
The present invention relates to a motor control device and a compressor capable of suppressing efficiency reduction due to conduction loss, while obtaining high reliability. A motor control device (1) configured to switch the number of turns of three motor windings (20, 21, 22) incorporated in a three-phase motor (2) operating with three-phase AC power includes a low turn side switch (120) connected between a first neutral point (Y0) of the three-phase motor (2) and low turn side connection points (N200, N220) of the two motor windings; and a high turn side switch (121) connected between a second neutral point (Y1) of the three-phase motor (2) and high turn side connection points (N201, N221) of two motor windings. The low turn side switch (120) and the high turn side switch (121) are bidirectional switches made up of semiconductor devices.