Electric Oil Pump Control System for Cold Climate Startup
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Solution Overview
Problem
Existing control systems for electric vehicles face challenges in starting the electric oil pump smoothly, especially in cold climates where high oil viscosity hinders the electric motor's ability to generate sufficient power for the electric oil pump, leading to potential startup issues and inefficiencies.
Innovation Solution
A control system that activates the electric oil pump with a higher duty cycle when starting, using a sensorless motor to ensure smooth startup and reduce the burden on the motor, and optionally continues to drive the electric oil pump during engine startup to avoid interference with the mechanical oil pump's discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric motor is started under high oil viscosity conditions (cold climate), then the electric oil pump may not start smoothly due to insufficient power, but increasing the motor power would increase system complexity and cost
Solution Approach 1:
The patent applies dynamics by making the duty cycle of the electric motor variable rather than fixed. The control device adjusts the duty cycle based on operating conditions: using a first (higher) duty cycle during startup or cold conditions to ensure reliable pump operation, and a second (lower) duty cycle during normal operation to reduce power consumption. This dynamic adjustment resolves the contradiction between ensuring startup reliability and maintaining simple system design.
2Power
If the electric motor runs at high duty cycle continuously, then the electric oil pump can maintain high hydraulic pressure, but power consumption increases unnecessarily during normal operation
Solution Approach 1:
The control device dynamically adjusts the duty cycle based on system needs. During startup or cold conditions, a higher first duty cycle is used to ensure the pump generates sufficient hydraulic pressure. Once the system is warmed up and operating normally, the duty cycle is reduced to a lower second value, maintaining adequate pressure while significantly reducing power consumption. This resolves the contradiction between power output and energy efficiency.
Solution Approach 2:
The patent changes the operating parameter (duty cycle) of the electric motor based on system conditions. By switching between a first duty cycle value (higher) and a second duty cycle value (lower), the system adapts its power output to match actual demands, ensuring sufficient hydraulic pressure when needed while minimizing energy consumption during normal operation.
3Reliability
If the electric oil pump is started before the mechanical oil pump, then the electric pump may interfere with the mechanical pump's discharge, but delaying startup reduces lubrication effectiveness
Solution Approach 1:
The control device uses feedback from the ignition switch state and system temperature to determine the optimal startup timing and duty cycle of the electric oil pump. When the ignition is on and conditions indicate cold operation, the electric pump starts with a higher duty cycle to ensure immediate lubrication. When the system is warm or the mechanical pump is operating normally, the electric pump's duty cycle is reduced or it is delayed in startup, preventing interference with the mechanical pump's discharge while maintaining lubrication effectiveness.
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 reliable and efficient startup of the electric oil pump even in cold conditions by increasing the duty cycle for initial startup and reducing power consumption when not required for lubrication, while avoiding interference with the mechanical oil pump's operation.
Implementation Method 1
an electric oil pump driven by a pumping motor to generate hydraulic pressure
Data Source
AI summary
A control system for electric vehicle is provided. The control system is applied to an electric vehicle (Ve) having a motor (2, 3) and an electric oil pump (19) driven by a pumping motor (20). The control system is configured to activate the electric oil pump (19) with a predetermined duty cycle when a main switch is turned on to bring the vehicle (Ve) into a ready-on state where the vehicle (Ve) is ready to travel.