Motor Torque Control via Voltage Phase Angle Modulation
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Solution Overview
Problem
Current methods for controlling AC motor torque in hybrid or electric vehicles face challenges in determining optimal voltage amplitude and phase angle to maximize torque while ensuring high DC bus voltage utilization, with existing approaches struggling to quickly and continuously calculate and control motor torque due to nonlinear torque changes with respect to the voltage phase angle.
Innovation Solution
A method and system that fix the voltage amplitude and vary the voltage phase angle to control motor torque, using a calculating component to calculate the optimal voltage phase angle based on command torque, motor torque, angular velocity, and voltage amplitude, ensuring motor torque changes linearly with respect to the voltage phase angle within a certain range, thereby stabilizing and maximizing torque control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If both voltage amplitude and voltage phase angle are regulated to control motor torque, then motor torque control flexibility is improved, but it becomes difficult to determine optimal parameters to maximize torque and DC bus voltage utilization
Solution Approach 1:
The patent extracts the voltage phase angle control from the combined amplitude-phase control system, fixing the voltage amplitude at its maximum value and using only voltage phase angle modulation to control motor torque. This separation simplifies the control parameters from two variables (amplitude and phase) to one variable (phase only), making it easier to determine optimal parameters while maintaining torque control flexibility.
Solution Approach 2:
The patent changes the control parameter from voltage amplitude modulation to voltage phase angle modulation. By fixing the voltage amplitude at its maximum value and varying only the phase angle, the system achieves torque control with a single parameter, resolving the complexity of determining optimal values for both amplitude and phase simultaneously.
2Productivity
If voltage amplitude is fixed and voltage phase angle is varied to control motor torque, then DC bus voltage utilization rate is improved, but motor torque changes nonlinearly with voltage phase angle making quick and continuous calculation difficult
Solution Approach 1:
The patent operates within a specific monotonous range of voltage phase angles (0 to π/2 or 0 to 90 degrees) where the motor torque changes linearly with the voltage phase angle. By constraining the phase angle to this linear range, the system maintains high DC bus voltage utilization while enabling quick and continuous torque calculation through simple linear relationships rather than complex nonlinear computations.
3Speed
If voltage phase angle is varied within a monotonous range to linearize torque changes, then torque control speed is improved, but voltage utilization range is limited
Solution Approach 1:
The patent dynamically adjusts the operating point within the linear monotonous range of voltage phase angles based on the required torque. By using feedback control and appropriately selecting the phase angle within the 0 to π/2 range, the system achieves both fast linear torque control and adequate torque coverage for typical operating conditions, balancing control speed with operational versatility.
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 approach allows for quick and continuous control of motor torque, improving DC bus voltage utilization by maintaining a constant voltage amplitude and adjusting the voltage phase angle, ensuring motor torque stability and maximizing utilization while simplifying torque control by linearizing torque changes with respect to the voltage phase angle.
Implementation Method 1
converting via the inverter a direct current voltage to the voltage vector according to the switching signal
Data Source
Figure 1
Figure 2~3
AI summary
A method and system are provided for controlling a motor 10. The method includes obtaining via a signal unit 60 electrical signals of the motor. The electrical signals include a motor torque and an angular velocity. The method further includes calculating via the calculating component a voltage phase angle of a voltage vector. A command torque, the motor torque, the angular velocity and a voltage amplitude of the voltage vector are inputs of the calculating component. The method further modulating via a modulator 40 the voltage phase angle and the voltage amplitude to a switching signal controlling an inverter 20. The method further includes converting via the inverter a direct current voltage to the voltage vector according to the switching signal and applying the voltage vector to the motor 10.