Brushless Compressor Speed Control for On-Board Current Limits
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Solution Overview
Problem
Compressor modules in motor vehicles face challenges in providing reliable and environmentally friendly operation, particularly under unfavorable conditions, where increased mechanical load leads to higher current consumption, risking overloading of the on-board electrical system.
Innovation Solution
A compressor module with a speed-controlled brushless electric motor and an electronic control unit that adjusts target speeds based on mean motor current, switching to a lower speed when a predefined current limit is reached, using existing motor electronics to manage current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mechanical load on the brushless direct-current motor is increased to provide sufficient compressed air under unfavorable conditions, then the compressed air supply capability is improved, but the current consumption increases and risks overloading the on-board electrical system
Solution Approach 1:
The patent implements dynamic speed control of the brushless direct-current motor by specifying different target speeds (first target speed and second target speed) based on operating conditions. The electronic control unit dynamically adjusts the motor speed to match the actual compressed air demand and electrical system capabilities, rather than operating at a fixed high speed. This dynamic adjustment allows the system to provide sufficient compressed air when needed while reducing current consumption during normal operation or when electrical load is a concern.
2Use of energy by moving object
If the motor speed is reduced to limit current consumption, then the electrical system is protected from overloading, but the compressed air supply capability may be insufficient under unfavorable conditions
Solution Approach 1:
The patent changes the operating parameters of the brushless direct-current motor by specifying different target speeds (first target speed n1,soll and second target speed n2,soll) depending on the mean motor current. The electronic control unit monitors the mean motor current and adjusts the target speed parameter accordingly - maintaining the first target speed when current is within limits, and switching to the second target speed when the current approaches the maximum permissible value. This parameter change ensures both electrical system protection and adequate compressed air supply.
3Use of energy by moving object
If frequent speed changes are implemented to optimize current consumption, then the electrical system is protected, but the acoustic output and operational smoothness are degraded
Solution Approach 1:
The patent implements a feedback control mechanism where the electronic control unit continuously monitors the mean motor current and adjusts the target speed accordingly. The feedback is based on the mean (averaged) current value rather than instantaneous fluctuations, which smooths the control responses and prevents excessive frequency of speed changes. This feedback approach protects the electrical system from overloading while minimizing acoustic disturbances and maintaining operational smoothness by responding only to sustained current trends rather than transient fluctuations.
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 approach ensures efficient operation by preventing overloading of the motor and electrical system while maintaining performance, reducing frequent speed changes, and optimizing acoustic output.
Implementation Method 1
a stator fitted with electromagnetic coils—that is, to a coil-wound stator—, a rotor fitted with permanent magnets... the stator coils are in turn periodically supplied with current in such a way that a rotating magnetic field is produced, this causing synchronous rotation of the rotor fitted with permanent magnets due to magnetic forces
Implementation Method 2
compressor generating the compressed air... assemblies which compress air
Data Source
AI summary
A compressor module has a compressor and a speed-controlled brushless electric motor for driving the compressor. A motor current is produced during operation of the electric motor. The electric motor is assigned a motor electronics system with an electronic commutator and a speed controller. The compressor module is connected to or has an electronic control unit. The control unit is configured to specify, depending on the mean motor current, one of at least two different target speeds for the electric motor, specifically at least a predefined first target speed and a predefined second target speed, which is lower than the predefined first target speed, and to change over from specifying the predefined first target speed to specifying the predefined second target speed when the mean motor current reaches or exceeds a specified motor current limit value. The compressor module can be for a compressed-air supply system of a vehicle.