Motor Winding Switching Between Star and Delta for Wide-Speed Efficiency
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Solution Overview
Problem
Permanent magnet motors face inefficiencies in both low and high speed rotations due to limitations in stator winding configurations, where increasing turns for low speed efficiency prevents high speed operation and vice versa, and existing motor driving devices fail to adequately address these issues, especially in terms of energy savings.
Innovation Solution
A motor driving device with a connection switching unit that uses mechanical switches and an excitation coil to switch between star and delta connections, allowing for efficient high speed operation and reduced power consumption by controlling the energization of the excitation coil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the number of turns of stator winding is increased, then motor efficiency in low speed rotation is improved, but inductive voltage rises and motor cannot operate at higher rotational speeds
Solution Approach 1:
The patent applies the dynamics principle by making the stator winding connection configuration changeable between star and delta connections based on operating conditions. The connection switching unit dynamically reconfigures the stator windings: star connection for low speed high efficiency operation, and delta connection for high speed operation, allowing the motor to adapt to different speed requirements while maintaining optimal performance in each regime.
Solution Approach 2:
The patent applies parameter changes by altering the electrical connection parameters of the stator windings. By switching between star and delta connections, the effective number of turns and impedance characteristics of the stator winding are changed, which adjusts the inductive voltage and current characteristics to match different operating speed requirements.
2Speed
If the number of turns of stator winding is decreased, then motor can operate at higher rotational speeds, but current increases and inverter loss increases reducing efficiency
Solution Approach 1:
The connection switching unit dynamically changes the stator winding configuration from delta to star connection when high speed operation is required. This dynamic reconfiguration reduces the inductive voltage and allows the motor to operate at higher speeds while the control system adjusts to maintain efficiency by optimizing the current path through the windings.
Solution Approach 2:
By switching from delta to star connection, the patent changes the electrical parameters of the stator winding, specifically reducing the line-to-neutral voltage and adjusting the current characteristics. This parameter change enables high speed operation while managing the current levels to minimize inverter losses.
3Adaptability or versatility
If mechanical switches are used for connection switching, then switching between star and delta connections is achieved, but electric power consumption for maintaining switch status is not considered reducing overall efficiency improvement
Solution Approach 1:
The patent replaces the traditional mechanical switch system with an electromagnetic relay-based connection switching unit. The electromagnetic relay uses an excitation coil to open or close the mechanical switch contacts, allowing for controlled switching between star and delta connections. This substitution enables remote and automated control of the connection configuration while reducing the power consumption associated with maintaining switch status, as the relay can be energized only during switching transitions rather than continuously.
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
Enables efficient operation of motors at both high and low speeds, achieving high cooling/heating capacity and energy savings by appropriately switching the stator winding connections and managing excitation coil energization.
Implementation Method 1
an excitation coil opening or closing the mechanical switch by being energized or non-energized with excitation current
Data Source
AI summary
A motor driving device that is a device for driving a motor including stator windings, includes: a connection switching unit that includes relays as mechanical switches connected to the stator windings and excitation coils opening or closing the relays by being energized or non-energized with excitation current and switches connection condition of the stator windings to either of first connection condition (star connection) and second connection condition (delta connection) different from the first connection condition by opening or closing the relays; and an inverter that supplies AC drive voltages to the stator windings.