Drive Unit Torque Control via Inner Effective Torque
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Solution Overview
Problem
Current test stand control methods struggle to accurately control dynamic rotational speed and torque profiles of drive units, particularly in internal combustion engines, due to limited adjustment dynamics and the inability to independently control torque during dynamic test runs, leading to poor control results and high demands on test stand systems.
Innovation Solution
The method involves controlling the inner effective torque of the drive unit using a feed-forward control approach, accounting for actuating dynamics through a transfer function and observer algorithms, which decouples rotational speed and torque control, allowing for improved accuracy by compensating for different torque build-up delays across various drive units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the conventional control method N/MEFF is used where the load machine controls rotational speed and the drive unit controls torque, then the control system is simple to implement, but during dynamic test runs the torque cannot be controlled independently of rotational speed due to mass inertia coupling, leading to poor control accuracy
Solution Approach 1:
The control system is segmented into two independent control loops: one for rotational speed (controlled by the load machine) and one for inner effective torque (controlled by the unit controlling unit). This segmentation allows each variable to be controlled independently, breaking the coupling effect of mass inertia that plagues the conventional N/MEFF method. The inner effective torque is calculated by subtracting the inertia torque from the effective torque, enabling separate control of torque and speed during dynamic test runs.
Solution Approach 2:
The concept of 'inner effective torque' serves as an intermediary variable that bridges the gap between the measurable effective torque and the controllable torque parameter. By introducing this intermediate concept and calculating it through the relationship MINT_EFF = MEFF - IA*dω/dt, the system can control torque independently while accounting for the dynamic coupling effects through the observer algorithm that estimates the inertia torque.
2Adaptability or versatility
If dynamic test runs with rapid changes in rotational speed and torque are performed, then the test stand can meet modern requirements for drive unit testing, but the actuating dynamics of the drive unit cannot keep up with the rapid changes, resulting in delayed torque response
Solution Approach 1:
The feed-forward control mechanism performs preliminary action by calculating the required manipulated variable changes in advance based on the desired inner effective torque profile. The control system anticipates the torque requirements and prepares the appropriate control signals before the actual torque changes are needed, compensating for the inherent delays in the drive unit's actuating dynamics. This allows the system to track dynamic torque profiles more accurately despite the slow response of the drive unit.
3Ease of manufacture
If the manipulated variable is determined from a static characteristic map based on stationary operating points, then the control implementation is straightforward, but during dynamic operation the measured effective torque does not match the characteristic map values, leading to incorrect manipulated variable values
Solution Approach 1:
The control system transitions from static characteristic maps to dynamic control by continuously calculating the inner effective torque based on real-time measurements of effective torque and rotational speed, along with the known mass inertia. The observer algorithm dynamically estimates the inner effective torque by compensating for inertia effects, allowing the system to adapt to changing operating conditions during dynamic test runs rather than relying on pre-measured stationary data points.
Data Source
AI summary
Aspects of the present disclosure are directed to controlling an inner effective torque or an effective torque of a drive unit via a unit controlling unit. In some embodiments, the control method may include providing desired values for the inner effective torque or the effective torque and determining actual values for the inner effective torque or the effective torque during operation of the drive unit on a test stand, and in that actuating dynamics of the drive unit are taken into account in the control by means of a transfer function by correcting the desired values of the control with the transfer function or in that for controlling the inner effective torque or the effective torque of the drive unit, a feed forward control of a manipulated variable of the drive unit is used.