Rotating Electrical Machine Control System Voltage Boosting
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Solution Overview
Problem
The existing rotating electrical machine control systems face challenges in managing power consumption and preventing overcurrents due to response delays in voltage measurement and feedback control, leading to excessive current draw from the battery, especially during high torque and high rotational speed operations.
Innovation Solution
A rotating electrical machine control system that includes a frequency converting portion and a voltage converting portion, with a control portion that limits the increase in boost command values when power consumption exceeds a predetermined electric-power limitation value, thereby suppressing voltage output and preventing overcurrents by setting the electric-power limitation value based on the delay time in voltage measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the boost command value is increased to raise the voltage output for high torque operation, then the power consumption increases, but this causes excessive current draw from the battery due to response delay in voltage measurement
Solution Approach 1:
The control device performs preliminary action by predicting future power consumption based on the rate of change of the boost command value and the known delay time. This allows the system to anticipate excessive power consumption before it actually occurs, enabling preventive control actions to be taken in advance rather than reacting after the overcurrent condition arises.
Solution Approach 2:
The control device applies preliminary anti-action by limiting the rate of change of the boost command value when prediction indicates that power consumption will exceed the allowable limit. This counteracts the tendency toward excessive current draw before it can occur, preventing the harmful effect rather than merely responding to it after detection.
2Device complexity
If the voltage measurement and feedback control are performed with normal response time, then the control system is simpler, but the voltage output lags behind the actual voltage causing torque mismatch
Solution Approach 1:
The control device uses feedback by continuously monitoring the actual power consumption and comparing it with the predicted power consumption. This feedback loop allows the system to adjust the boost command value's rate of change in real-time, compensating for the inherent delay in voltage measurement and ensuring accurate torque control without requiring a more complex control architecture.
3Speed
If the field-weakening control is performed to reduce counter electromotive force at high rotational speed, then the motor can be controlled, but the magnetic field intensity is reduced resulting in lower maximum torque
Solution Approach 1:
The control device changes the parameter of voltage output dynamically by adjusting the boost command value's rate of change based on predicted power consumption. This allows the system to optimize the voltage output for high-speed operation without unnecessarily reducing the magnetic field strength, thereby maintaining higher maximum torque capability compared to traditional field-weakening control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively reduces power consumption and prevents overcurrents by limiting the boost command value, ensuring the DC power source does not exceed its allowable electric power, thus improving the control system's efficiency and preventing battery overcurrents.
Implementation Method 1
a voltage converting portion that boosts an output of the DC power source
Implementation Method 2
a frequency converting portion that converts an output of the DC power source to an AC output
Implementation Method 3
A motor as a rotating electrical machine (a motor and a generator) operates based on a principle of generating a force (torque) by a magnetic field and a current
Implementation Method 4
during rotation of the motor, the force is applied in the magnetic field, causing a so-called counter electromotive force. The counter electromotive force is generated in a direction that prevents the current flow
Data Source
AI summary
A rotating electrical machine control system includes a frequency converting portion that is interposed between a rotating electrical machine for driving a vehicle and a DC power source for supplying electric power to the rotating electrical machine, and that converts an output of the DC power source to an AC output at least during powering operation of the rotating electrical machine; a voltage converting portion that is interposed between the DC power source and the frequency converting portion, and that boosts the output of the DC power source based on a boost command value which is set according to a target torque and a rotational speed of the rotating electrical machine; and a control portion for controlling the frequency converting portion and the voltage converting portion.