Brushless Motor Control Noise Reduction via Voltage Smoothing
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Solution Overview
Problem
High-frequency noise in the rotation angle speed and motor electric current values leads to vibrations and abnormal noise in brushless motor control systems, degrading the user experience and responsiveness in electric power steering applications.
Innovation Solution
A motor control device with a correction value computing unit that smooths the basic voltage values using a correction value smoothing unit, reducing high-frequency noise and improving responsiveness by computing voltage command values based on smoothed values, independent of rotation angle speed and motor electric current values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If non-interference control is implemented using rotation angle speed and motor electric current values, then responsiveness and following capability are improved, but high-frequency noise causes vibrations and abnormal noise
Solution Approach 1:
The patent applies preliminary action by computing the non-interference control amount in advance based on rotation angle speed and motor electric current values, then smoothing this computed amount before applying it to the voltage command value. This preliminary smoothing action prevents high-frequency noise from propagating to the motor control output, thereby reducing vibrations and abnormal noise while maintaining the responsiveness benefits of non-interference control.
2Speed
If high-frequency components are used in motor control computation, then responsiveness is improved, but user experience degrades due to physical disorder feeling
Solution Approach 1:
The patent introduces an intermediary smoothing computation step between the detection of rotation angle speed and motor electric current values and the application of non-interference control to the voltage command value. This intermediary smoothing function acts as a mediator that filters out high-frequency noise components while preserving the essential control signals, thereby eliminating the feeling of physical disorder in steering without sacrificing responsiveness.
Data Source
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AI summary
A motor control device of the present invention includes: target electric current value setting units (15 and 16) that set target electric current values that should be supplied to a motor (1), basic voltage value computing units (511, 521, 51a, and 52a) that compute basic voltage values for driving the motor, a rotation angle speed computing unit (23) that computes a rotation angle speed of the motor, correction value computing units (50, 512, 515, 516, 522, 525, and 526) that compute correction values for correcting the basic voltage values based on motor electric current values and a rotation angle speed of the motor, correcting units (513 and 523) that obtain voltage command values by correcting the basic voltage values by the correction values computed by the correction value computing units, and a driving unit (13) that drives the motor by using voltage command values. The correction value computing units include correction value smoothing units (50, 515, 516, 525, and 526) for obtaining smoothed correction values.