Motor Control During Overmodulation With Carrier Phase Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional motor control systems during overmodulation fail to appropriately control motor performance due to varying phase differences between the carrier wave and voltage command, leading to amplitude and phase changes in the voltage output from the inverter.
Innovation Solution
A motor control device with a current control unit, carrier wave frequency adjusting unit, and gate signal generation unit that adjusts the carrier wave frequency to change the phase difference and corrects the amplitude and phase of the voltage command based on the phase of the carrier wave, ensuring appropriate motor control during overmodulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If synchronous PWM control with overmodulation is used to maintain voltage output when modulation rate exceeds predetermined value, then the voltage amplitude can be maintained at desired value, but the phase difference between carrier wave and voltage command varies causing amplitude and phase changes in voltage output
Solution Approach 1:
The control device calculates the phase difference between the voltage command and carrier wave, and uses this feedback to determine corrected amplitude and phase values for the voltage command during overmodulation, ensuring accurate motor control
Solution Approach 2:
The system dynamically adjusts the amplitude and phase parameters of the voltage command based on the calculated phase difference, transforming the control approach from fixed parameter to adaptive parameter adjustment to maintain control accuracy during overmodulation
2Measurement precision
If carrier wave frequency is adjusted to change phase difference during overmodulation, then accurate voltage control is achieved, but control complexity increases
Solution Approach 1:
The carrier wave frequency is dynamically adjusted to maintain the desired phase relationship between voltage command and carrier wave, enabling adaptive phase control without requiring complex additional hardware
Data Source
AI summary
The present invention addresses the problem of properly performing motor control during overmodulation. In a motor control device 1, a carrier wave frequency adjusting unit 16 adjusts a carrier wave frequency fc so as to change a voltage phase error Δθv representing the phase difference between three-phase voltage commands Vu*, Vv*, Vw* and a triangular wave signal Tr. When a modulation factor H in accordance with the voltage amplitude ratio between the DC power supplied from a high voltage battery to an inverter and AC power output from the inverter to a motor exceeds a predetermined value, for example, 1.15, a current control unit 14 corrects the amplitudes and phases of a d-axis voltage command Vd* and a q-axis voltage command Vq* on the basis of a carrier wave phase difference Δθcarr representing the phase of the triangular wave signal Tr.