Electric Motor Control Apparatus for Torque Responsiveness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric motor control technologies face challenges in achieving both stability and torque responsiveness, particularly during sharp changes in rotational speed and torque, which can occur during skid or grip events in electric vehicles.
Innovation Solution
A control apparatus for electric motors that includes a voltage command generation unit and a rate-of-change restriction unit, which generates a phase-controlled rectangular-wave voltage command and adjusts the rate of change based on predetermined values for rotational speed and torque changes, lessening restrictions on phase shifts during abrupt changes to prioritize torque responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the voltage phase of the rectangular-wave voltage is controlled based on torque command to improve torque responsiveness, then the torque responsiveness is improved, but the control stability deteriorates during abrupt rotational speed changes
Solution Approach 1:
The patent applies dynamics by making the rate-of-change restriction value variable based on operating conditions. The controller dynamically adjusts the restriction level on voltage phase change rate according to the current rotational speed and torque command, allowing flexible adaptation between stability and responsiveness requirements in different operating states
Solution Approach 2:
The patent changes the parameter of voltage phase change rate restriction based on operating conditions. By monitoring rotational speed and torque command, the system adjusts the restriction value to allow faster phase changes when needed for responsiveness while maintaining stricter restrictions under normal conditions for stability
2Measurement precision
If the voltage phase of the rectangular-wave voltage is controlled based on torque deviation to reduce torque deviation, then the torque accuracy is improved, but the controllability against sharp changes in rotational speed and torque deteriorates
Solution Approach 1:
The system dynamically switches between control strategies based on operating conditions. During abrupt rotational speed changes or torque variations, the controller prioritizes phase change responsiveness over torque accuracy, while under normal conditions it maintains strict torque accuracy through deviation-based control
Solution Approach 2:
The controller performs preliminary detection of abrupt changes in rotational speed or torque command, and in advance adjusts the rate-of-change restriction to allow faster voltage phase changes before the actual torque deviation becomes significant, preventing loss of controllability
Data Source
AI summary
A PI calculation unit (230) of a rectangular-wave voltage control unit (200) calculates a control deviation by performing a PI calculation on a torque deviation (ΔTrq) relative to a torque command value (Trqcom), and outputs a voltage phase (φv) of a rectangular-wave voltage in accordance with the control deviation. A rate-of-change limiter (235) imposes a restriction on the rate of change of the voltage phase (φv). Here, the rate-of-change limiter (235) lessens the restriction on the rate of change of the voltage phase (φv), when the rate of change of the rotational speed of an electric motor (M1) is larger than a predetermined value representing an abrupt change of the rotational speed of the electric motor (M1).