Motor Speed Damping Control for Braking Disturbance Separation
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Solution Overview
Problem
In vehicles with low resonance frequency, distinguishing motor speed variations caused by torsional vibrations from those caused by disturbance components like braking is difficult, leading to insufficient correction and potential erroneous calculation of correction torque.
Innovation Solution
A motor control device and method that include a controller outputting a first torque instruction signal and a damping control unit with a first high-pass filter for the motor speed signal, a second high-pass filter for the estimated motor speed signal, and a low-pass filter for the motor speed deviation signal, which together reduce error components and improve motor speed estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-pass filter is used to detect torsional vibrations in motor speed, then vibration detection capability is improved, but in vehicles with low resonance frequency, disturbance components like braking cannot be distinguished from vibrations leading to erroneous correction torque calculation
Solution Approach 1:
The patent segments the correction torque calculation into two distinct parts: a vibration correction torque component (using high-pass filter) and a disturbance correction torque component (using low-pass filter). This segmentation allows separate handling of vibration suppression and disturbance compensation, preventing erroneous calculation by directing different signal components to appropriate correction paths.
Solution Approach 2:
The patent introduces an intermediary disturbance observer that estimates disturbance torque components (such as braking forces) separately from the vibration detection path. This intermediary observer acts as a mediator that identifies and isolates disturbance signals before they can be mistakenly interpreted as torsional vibrations, thereby improving reliability of the overall control system.
2Measurement precision
If the high-pass filter cutoff frequency is reduced to detect low-frequency torsional vibrations, then vibration detection sensitivity is improved, but the ability to distinguish from disturbance components deteriorates
Solution Approach 1:
The patent segments the frequency spectrum handling by using a high-pass filter specifically for vibration detection while employing a separate low-pass filter for disturbance estimation. This segmentation allows the high-pass filter to operate at lower cutoff frequencies for improved vibration sensitivity without compromising disturbance discrimination, as the disturbance path uses complementary filtering.
Solution Approach 2:
The disturbance observer serves as an intermediary that specifically targets low-frequency disturbance components (such as braking forces) before they can contaminate the vibration detection signal. This intermediary processing step enables the system to maintain high vibration detection sensitivity while effectively distinguishing and separately handling disturbance components.
3Stability of the object's composition
If correction torque is applied to suppress torsional vibrations, then motor control smoothness is improved, but erroneous correction due to disturbance misidentification reduces control accuracy
Solution Approach 1:
The patent segments the torque correction into two independent components: vibration correction torque (for smoothness) and disturbance correction torque (for accuracy). By calculating these separately using different filtering approaches, the system maintains control smoothness through vibration suppression while preserving estimation accuracy through proper disturbance compensation, preventing erroneous corrections.
Solution Approach 2:
The disturbance observer acts as an intermediary that accurately estimates disturbance torque components before they affect the motor speed estimation. This intermediary estimation allows the system to apply appropriate disturbance correction torque separately, ensuring that vibration suppression actions are not mistakenly applied to disturbance-induced speed variations, thereby maintaining both smoothness and accuracy.
Data Source
AI summary
Provided is a motor control device that can reduce an error component resulting from braking or the like to bring an estimated motor speed closer to an actual motor speed, thereby improving the accuracy of control of a motor. The motor control device includes a controller 6 that outputs a first torque instruction signal that is an instruction to specify a torque of an electric motor 1, and a damping control unit 500. The damping control unit 500 includes a first high-pass filter 50f that receives input of a motor speed signal indicating a speed of the electric motor 1, the first high-pass filter 50f outputting a first signal, a second high-pass filter 50d that receives input of an estimated motor speed signal obtained from the first torque instruction signal, the second high-pass filter 50d outputting a second signal, and a low-pass filter 50g that receives input of a motor speed deviation signal indicating a deviation between the first signal and the second signal, the low-pass filter 50g obtaining a low-frequency component from the motor speed deviation signal and outputting the low-frequency component as a third signal.