Sensorless Brushless Motor Control for Low-Temperature Oil Discharge
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Solution Overview
Problem
Existing electric pumps using sensorless brushless motors face inefficiencies at low temperatures due to increased viscosity of oil, leading to reduced rotary speed and insufficient oil discharge, which requires larger motors and is costly in terms of space, weight, and efficiency.
Innovation Solution
An electric pump with a control unit that switches from constant current control to constant voltage control at a higher motor applied voltage when the temperature drops below a predetermined level, ensuring the necessary oil discharge amount is maintained by increasing the motor applied voltage, thereby enhancing torque output and oil supply efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the motor is upsized to generate large torque at low temperature, then the necessary oil discharge amount can be maintained, but the space, weight and cost of the motor increase
Solution Approach 1:
The patent applies dynamics by switching the motor control mode from constant current control to constant voltage control when the temperature drops below a predetermined level. This dynamic control strategy adjustment allows the motor to operate efficiently across different temperature conditions without requiring an oversized motor design, thereby maintaining oil discharge requirements while avoiding increased motor weight and cost.
Solution Approach 2:
The patent changes the control parameters based on temperature conditions. By detecting temperature and switching between constant current control and constant voltage control modes, the system optimizes motor performance for low-temperature operation without requiring physical changes to the motor size, thus maintaining productivity while avoiding weight and cost penalties.
2Productivity
If the motor is upsized to generate large torque at low temperature, then the necessary oil discharge amount can be maintained, but the space occupied by the motor increases
Solution Approach 1:
The control mode dynamically switches based on temperature conditions, allowing a compact motor to deliver required performance across different operating conditions. The dynamic adjustment between constant current and constant voltage control enables the motor to maintain necessary oil discharge at low temperatures without requiring increased motor volume.
Solution Approach 2:
By changing control parameters (from constant current to constant voltage control) based on temperature detection, the system enables a compact motor to achieve the required torque output at low temperatures through optimized electrical control rather than physical size increase, thus maintaining space efficiency.
3Reliability
If constant current control is used at low temperature, then the motor can operate, but the inductive voltage decreases and the motor may step out when rotary position is not detected
Solution Approach 1:
The control strategy dynamically switches from constant current control to constant voltage control when temperature drops below a predetermined level. This dynamic adjustment prevents the inductive voltage from decreasing to problematic levels, ensuring that rotary position detection remains effective and the motor does not step out, thereby maintaining reliable operation at low temperatures.
Solution Approach 2:
The system uses temperature detection as feedback to determine when to switch control modes. By monitoring temperature and switching to constant voltage control when it drops below a threshold, the system proactively prevents the conditions that would cause inductive voltage decrease and loss of synchronism, ensuring continuous reliable operation with proper position detection.
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
The solution ensures the electric pump can consistently supply the required amount of oil to the transmission even at low temperatures, improving efficiency and preventing motor synchronization loss by adjusting the control strategy based on temperature changes.
Implementation Method 1
The sensorless brushless motor detects a rotary position of a rotor by using an inductive voltage which is induced by a coil wound on a stator
Implementation Method 2
a sensorless brushless motor (hereinafter referred to as a motor) driving the pump body
Data Source
AI summary
An electric pump includes a pump body, a sensorless brushless motor, and a control portion controlling the motor to perform a constant current control and a constant voltage control to discharge a necessary discharge amount of an operation fluid from the pump body, the control portion controlling the motor to switch from the constant current control to the constant voltage control at a predetermined temperature of the operation fluid and at a predetermined motor applied voltage. The control portion controls the motor to switch from the constant current control to the constant voltage control at a motor applied voltage which is higher than the predetermined motor applied voltage when a temperature of the operation fluid is lower than the predetermined temperature to discharge the necessary discharge amount of the operation fluid from the pump body.