Sensorless Gearbox Oil Pump Startup Under Variable Oil Temperature
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Solution Overview
Problem
Existing control methods for brushless oil pumps without position sensors struggle to reliably start the pump across varying oil temperatures, as single PID regulator calibration fails to maintain below diagnostic current thresholds, leading to potential overcurrent issues both hot and cold.
Innovation Solution
Adapting the current regulator parameters by detecting blockages and using the phase current as an estimator for oil temperature, allowing for increased open-loop current calibration above closed-loop thresholds, enabling the pump to operate effectively at low temperatures without an oil temperature sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single PID regulator calibration is used for the brushless motor controller, then the control is simple and cost-effective, but the pump cannot reliably start across varying oil temperatures as the calibration fails to maintain below diagnostic current thresholds
Solution Approach 1:
The patent implements dynamic adaptation of PID regulator parameters based on operating conditions. The controller automatically adjusts the proportional, integral, and derivative gains according to the detected oil temperature and pump operating state, enabling reliable pump starting across the full temperature range while maintaining a single hardware configuration without additional sensors.
Solution Approach 2:
The patent changes the parameters of the PID regulator dynamically according to temperature conditions. By detecting oil temperature and selecting appropriate parameter sets, the system adapts the controller behavior to match varying viscous torques at different temperatures, ensuring reliable pump starting without exceeding diagnostic current thresholds.
2Reliability
If the PID current regulator is calibrated to ensure a good hot start, then the pump starts reliably at high temperatures, but the same PID regulator will cause the current threshold to be exceeded when cold
Solution Approach 1:
The patent applies different PID regulator parameter sets based on detected oil temperature. For hot conditions, parameters are optimized for reliable starting with lower viscous torque. For cold conditions, parameters are adjusted to provide higher initial torque while maintaining current below diagnostic thresholds, thus preventing overcurrent damage while ensuring reliable cold starts.
Solution Approach 2:
The system dynamically adapts the PID parameters in response to temperature changes. The controller monitors operating conditions and automatically switches between pre-calibrated parameter sets or continuously adjusts parameters to optimize performance for the current temperature, preventing both hot and cold start problems.
3Reliability
If the PID current regulator is calibrated to ensure a good cold start, then the pump starts reliably at low temperatures, but the same PID regulator will cause the current threshold to be exceeded when hot
Solution Approach 1:
The patent implements temperature-dependent PID parameter calibration. When cold operating conditions are detected, the controller uses parameter sets that provide sufficient torque to overcome high viscous resistance. When hot conditions are detected, different parameter sets are applied that prevent excessive current while maintaining reliable operation, thus eliminating overcurrent issues at both temperature extremes.
Solution Approach 2:
The system dynamically adjusts PID parameters based on real-time temperature detection. The controller monitors oil temperature and automatically adapts the regulator characteristics to match the viscous torque characteristics at different temperatures, ensuring reliable starting without exceeding current thresholds under any operating condition.
4Measurement precision
If an oil temperature sensor is inserted into the lubrication circuit to adapt PID parameters, then the control accuracy is improved, but the device complexity and cost increase
Solution Approach 1:
The patent enables the brushless motor controller to self-detect oil temperature using existing components within the motor structure. By monitoring back-EMF characteristics, current draw patterns, and rotational speed relationships, the controller infers temperature without requiring external temperature sensors or additional wiring, thus maintaining control accuracy while avoiding increased complexity.
Solution Approach 2:
The patent makes the brushless motor controller perform multiple functions: it controls motor operation, monitors pump performance, detects oil temperature, and adapts PID parameters. By integrating temperature detection capabilities into the existing motor control system, the patent eliminates the need for separate temperature sensing hardware while maintaining the ability to adapt control parameters according to temperature conditions.
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
Ensures independent pump starting across temperature variations, reducing costs, enhancing reliability, and simplifying gearbox architecture by eliminating the need for a temperature sensor, while maintaining lubrication flow reliability.
Implementation Method 1
a method of controlling the start-up of a gearbox oil pump by a brushless electric motor
Implementation Method 2
measuring the back electromotive force of the inactive windings, known as voltage back-EMF
Data Source
Figure 1~2
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AI summary
Method for controlling the start-up of an oil pump (3) of a gearbox (1) by a brushless electric motor that has no position sensor, in which method the stator coils (S) are powered from the off mode in a constant-current open-loop control sequence until the pump reaches a speed threshold at which speed regulation switches over to closed-loop control on a setpoint corresponding to the lubrication flow rate required to ensure the reliability of the gearbox, but without in so doing exceeding a current threshold indicative of pump seizure, at which point motor control switches back over to the constant-current open-loop control sequence. The open-loop current setpoint is higher than the threshold for switching over to closed-loop control so that in the open-loop control mode the motor torque available at the pump is higher than in the closed-loop control mode.