Fuel Pump Pressure Control via Phase Current Analysis
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Solution Overview
Problem
Existing closed-loop feedback systems for fuel pumps are costly due to the need for pressure sensors, while open-loop systems are inaccurate and do not fully utilize energy savings, especially under varying conditions.
Innovation Solution
A closed-loop control system for fuel pumps that measures characteristic phase current as a function of speed, allowing for error compensation without a pressure sensor, using a calibration valve to maintain constant pressure and account for changes in viscosity and wear over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a closed-loop feedback system with pressure sensor is used, then pressure control accuracy is improved, but system cost and complexity increase
Solution Approach 1:
The patent extracts the pressure measurement function from a dedicated pressure sensor and implements it through the existing motor's phase current measurements. By analyzing the relationship between phase current and pump pressure, the system achieves pressure monitoring without adding a separate pressure sensing component, thereby reducing system complexity while maintaining control accuracy.
Solution Approach 2:
The patent introduces phase current as an intermediary parameter to indirectly measure pump pressure. Instead of directly measuring pressure with a sensor, the system uses phase current characteristics (which are already available for motor control) as a mediator to infer pressure conditions, thus avoiding the need for additional pressure sensing hardware.
2Device complexity
If an open-loop control system is used, then system complexity is reduced, but pressure control accuracy and energy efficiency deteriorate
Solution Approach 1:
The patent implements a feedback mechanism using phase current measurements to monitor pump pressure conditions. The controller compares actual phase current characteristics against expected values to detect pressure deviations and adjusts motor operation accordingly, providing closed-loop control without requiring external pressure sensors. This maintains pressure control accuracy while keeping the system relatively simple.
Solution Approach 2:
The patent enables the motor control system to serve dual purposes: both controlling motor operation and monitoring pump pressure conditions. The existing phase current measurement infrastructure is utilized for both torque control and pressure feedback, allowing the system to self-monitor and self-adjust without additional dedicated sensing or control components.
3Device complexity
If phase current measurement is used for pressure control, then pressure sensor cost is eliminated, but measurement precision under varying conditions may be affected
Solution Approach 1:
The patent compensates for variations in phase current characteristics caused by changing operating conditions (temperature, viscosity, wear) by dynamically adjusting the reference values and calibration parameters. The system adapts the phase current-to-pressure relationship based on actual operating conditions, maintaining measurement accuracy despite environmental variations without requiring additional sensors.
Data Source
AI summary
A closed loop control system for a fuel pump based on characteristics of speed, pressure, and current. The pressure generated by the pump system is increased at the point in time when the pump system is working against a dead head system (i.e., coasting) to a level that a calibration valve is opened to a determined working point. By measuring the characteristic phase current as a function of the speed, the characteristic is able to be compared, with the pre-calibrated value of the hardware to perform an error compensation algorithm. The error compensation is overlaid with the standard pressure characteristic as a function of speed and phase current, and uses the pre-calibrated opening pressure value (i.e., the inflection point) of the calibration valve and/or in addition the change of the speed to the initial (first calibration), or to a sliding average therefrom.