Air-Spring Compressor Mode Switching for BLDC Current Limits

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Solution Overview

Problem

Existing compressed-air supply systems in vehicles face challenges in efficiently managing power consumption by brushless direct-current motors (BLDC) in compressor modules, particularly under varying operating conditions, leading to potential overconsumption and the need for oversized motors to handle rare worst-case scenarios.

Innovation Solution

Implementing a compressed-air supply system with mode switching based on mean motor current, transitioning from closed to open operating modes when maximum current is reached, ensuring constant speed and reducing load without speed reduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the motor is oversized to handle rare worst-case scenarios, then reliability is improved, but device complexity and cost increase

Engineering Contradiction:

ImprovereliabilityVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies dynamics by switching the motor operating mode between closed-loop and open-loop control based on real-time current conditions. The control unit monitors motor current and dynamically adjusts the control strategy, transitioning from field-oriented control (closed-loop) to sine-wave commutation (open-loop) when current limits are approached, thereby enabling a smaller motor to reliably handle varying load conditions without requiring oversizing for rare worst-case scenarios.

Inventive Principle:

Principle #15Dynamics

2Use of energy by moving object

If the motor current is limited to avoid overconsumption, then energy efficiency is improved, but power output decreases

Engineering Contradiction:

Improvepower consumptionVSAvoidpower output

Core Design Contradiction:

Use of energy by moving objectVSPower

Solution Approach 1:

The patent applies parameter changes by monitoring motor current as a key parameter and adjusting control strategy based on current thresholds. When the mean motor current approaches the maximum allowable current, the control unit transitions from closed-loop field-oriented control to open-loop sine-wave commutation, effectively changing the operational parameters to maintain power consumption within limits while preserving adequate power output for normal operations.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The control system dynamically adapts between different control modes based on real-time current measurements. By switching between closed-loop and open-loop control strategies, the system optimizes energy efficiency during normal operation while maintaining the capability to deliver required power output, thus resolving the contradiction between limiting power consumption and maintaining power output.

Inventive Principle:

Principle #15Dynamics

3Use of energy by moving object

If speed control is implemented to reduce current consumption, then energy efficiency is improved, but speed stability deteriorates

Engineering Contradiction:

Improvecurrent consumptionVSAvoidspeed stability

Core Design Contradiction:

Use of energy by moving objectVSSpeed

Solution Approach 1:

The patent maintains constant motor speed throughout operation while dynamically switching control strategies based on current conditions. Rather than reducing speed to limit current consumption, the system uses field-oriented control for precise current management at constant speed, and transitions to sine-wave commutation when current limits are approached, thereby maintaining both energy efficiency and speed stability without compromising either parameter.

Inventive Principle:

Principle #15Dynamics

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 optimizes power usage by avoiding short-term peaks and allowing the system to operate efficiently across all conditions, maintaining performance while adhering to current limits without overdesigning the motor.

Implementation Method 1

the motor controller controls the current supply to the coils of the stator such that the 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

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

compressors are required for generating compressed air

Methodology Applied

Scientific EffectCompression: Compression

Data Source

PatentUS20260063120A1Operating strategy for limiting the power consumption of a brushless motor for electrically driven passenger-car air-spring compressors through mode switching

Publication Date: 2026.03.05 ZF CV SYST EURO BV

AI summary

A compressed-air supply system includes at least one compressed-air consumer, compressed-air lines, electrically controllable valves, a compressed-air controller for actuating the valves, a compressor having an electric motor as a drive, and a pressure reservoir. The compressed-air consumer can be pneumatically connected to the compressor and/or the pressure reservoir via the lines and the valves such that the compressed-air supply system can be operated either in an open or in a closed operating mode. The controller has an input for a current signal, which represents a motor current drawn or to be drawn by the electric motor. The controller is configured to actuate the valves in accordance with the open operating mode when a current signal is present at the current signal input, the current signal representing a mean motor current, the magnitude of which is equal to or greater than a maximum value for the motor current.