Magnetic Motor Speed Controller Torque Stability
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Solution Overview
Problem
Existing speed control methods for magnetic motors do not maximize the voltage saturation rate, resulting in suboptimal use of the motor's upper limit torque, leading to instability, inefficiency, and poor response characteristics.
Innovation Solution
A speed controller that limits the phase angle between d-axis and q-axis commanded voltage values, preventing the q-axis commanded current from exceeding its upper limit, thereby allowing the magnetic motor to operate at its maximum torque capacity with high stability, efficiency, and quick response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the voltage saturation rate is set smaller than the preset voltage saturation rate value to prevent current divergence, then the stability of the motor is improved, but the maximum voltage of the power converter cannot be applied to the motor, resulting in loss of torque capability
Solution Approach 1:
The patent applies dynamics by making the q-axis commanded current value dynamically adjustable based on the phase angle condition. Instead of using a fixed current limit, the system adapts the current command in real-time according to the relationship between d-axis and q-axis voltage components, allowing optimal torque output while maintaining stability across different operating conditions.
Solution Approach 2:
The patent changes the parameter of q-axis commanded current value based on the phase angle between d-axis and q-axis commanded voltage values. When the phase angle exceeds a predetermined threshold, the system modifies the current parameter to prevent voltage saturation, thereby resolving the contradiction between stability and power output.
2Power
If the q-axis commanded current value is increased to maximize torque output, then the power and torque of the motor are improved, but the phase angle between d-axis and q-axis commanded voltage values increases, causing voltage saturation and current divergence
Solution Approach 1:
The patent implements feedback by continuously monitoring the phase angle between d-axis and q-axis commanded voltage values and using this information to adjust the q-axis commanded current value. This closed-loop control ensures that the current is optimized for torque production while preventing voltage saturation, thus resolving the contradiction between power output and voltage stability.
Solution Approach 2:
The patent applies preliminary action by proactively limiting the q-axis commanded current value before voltage saturation occurs. By detecting the phase angle condition in advance and adjusting the current command accordingly, the system prevents current divergence while maximizing torque output within safe operating limits.
3Productivity
If the maximum voltage of the power converter is applied to the motor to maximize torque, then the productivity and torque capability are improved, but the phase angle increases causing the q-axis commanded current to exceed the upper limit, resulting in instability
Solution Approach 1:
The patent applies dynamics by dynamically adjusting the q-axis commanded current value based on real-time phase angle measurements. This allows the system to operate at maximum torque capability when conditions permit while automatically reducing current to maintain stability when the phase angle approaches problematic levels, resolving the contradiction between productivity and reliability.
Data Source
Figure 1
Figure 2A~2B
Figure 3~4
AI summary
The invention relates to a speed control method of a magnetic motor (1) and is capable of providing a speed controller of the magnetic motor (1) realizing highly stable, highly efficient and highly responsive control characteristics even around critical torque of the motor (1). When an excessive torque command value (or a q-axis commanded current value) greater than a torque maximum value (or a q-axis current) that can be outputted by the motor (1) is required, an input of speed control is limited so that the q-axis commanded current value does not increase up to a limit value.