Open-End Winding Motor Inverter Control for Common Mode Current
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Solution Overview
Problem
The open end winding type motor driving technique struggles to control zero-phase component voltage to zero on average, leading to the generation of common mode current, which causes losses and potential damage to the motor system.
Innovation Solution
A motor driving apparatus is designed to control the zero-phase component voltage by setting the same common mode voltage between two inverters, ensuring that the difference in zero-phase component voltages between the two inverters is zero, thereby removing circulating currents and minimizing total switching loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If open end winding type motor driving technique is used to increase phase voltage and improve voltage utilization rate, then output power is increased, but zero-phase component voltage cannot be controlled to zero on average, causing common mode current generation and motor efficiency reduction
Solution Approach 1:
The patent changes the control parameters of the inverters by introducing a zero-phase component voltage control mechanism. By adjusting the duty ratios of switching elements and controlling the common mode voltage, the system maintains the high output power capability of open end winding configuration while eliminating the harmful zero-phase component voltage that causes common mode current and energy losses.
2Ease of operation
If common mode voltage is not controlled between two inverters, then open end winding configuration can operate, but difference in zero-phase component voltages causes circulating current and total switching loss increase
Solution Approach 1:
The patent implements a feedback control mechanism where the controller continuously monitors the zero-phase component voltages of both inverters and adjusts the common mode voltage accordingly. This feedback loop ensures that the difference in zero-phase component voltages is minimized, thereby reducing circulating currents and switching losses while maintaining ease of operation.
3Device complexity
If Y connection is used to short-circuit one end of motor winding, then device complexity is reduced, but voltage utilization rate decreases and fuel efficiency deteriorates
Solution Approach 1:
The patent segments the motor winding control into two independent inverter systems, each controlling one end of the winding. This segmentation allows for higher voltage utilization and improved fuel efficiency compared to Y connection, while the controller integrates these segmented systems to manage the overall complexity, achieving a balance between device complexity and energy efficiency.
Data Source
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AI summary
A motor driving apparatus of driving a motor including a plurality of windings respectively corresponding to a plurality of phases is disclosed The motor driving apparatus includes a first inverter including a plurality of first switching elements and connected to a first end of each of the windings, a second inverter including a plurality of second switching elements and connected to a second end of each of the windings, and a controller connected to the first switching elements and the second switching elements and configured to determine an effective vector closest to a voltage vector corresponding to a preset voltage command of the motor as a duty of the plurality of second switching elements and to control pulse width modulation of the first switching elements using a value obtained by adding the effective vector corresponding to the duty of the second switching elements to the voltage command of the motor as a voltage command of the first inverter.