Brushless DC Motor Blockage Detection Without Speed Sensors
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Solution Overview
Problem
Existing methods for detecting blockages in brushless DC motors are inefficient and require speed sensors, making them costly and unreliable.
Innovation Solution
A blockage detector that determines power consumption at two different rotating field speeds and calculates a power quotient, comparing it to a threshold value to determine if the motor is blocked, without the need for a speed sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a speed sensor is used to detect blockages, then detection reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical speed sensor with an electrical measurement system that monitors power consumption at different rotating field speeds. By applying voltages at two different speeds and comparing the power consumption ratio, the system detects blockages without any mechanical sensors, thus resolving the contradiction between reliability and device complexity.
Solution Approach 2:
The electrical machine itself provides the detection mechanism through its own power consumption characteristics. The system uses the machine's inherent electrical properties (power consumption at different speeds) to detect blockages, eliminating the need for external sensing devices and making the system self-diagnostic.
2Reliability
If test signals are applied to detect blockages, then detection capability is improved, but energy consumption increases
Solution Approach 1:
The patent applies partial test signals at two different rotating field speeds rather than continuous full-power testing. By using a quotient comparison method with threshold values, the system achieves reliable blockage detection with minimal energy input, avoiding excessive energy consumption while maintaining detection capability.
3Ease of manufacture
If power consumption quotient method is used, then cost-effectiveness is improved, but measurement precision requirements increase
Solution Approach 1:
The patent transforms the measurement approach by using a quotient ratio of power consumptions at two different speeds rather than absolute power measurements. This parameter transformation reduces sensitivity to measurement errors and eliminates the need for high-precision absolute power measurement, making the system both cost-effective and sufficiently precise.
Data Source
AI summary
A blockage detector for detecting a blocked state of an electrical machine has: a first power determiner and a second power determiner for determining a first power consumption and a second power consumption of the electrical machine while a first phase voltage and a second phase voltage for operating at a first rotating field speed and a second rotating field speed are applied to the electrical machine, a quotient former for producing a power quotient between the first power consumption and the second power consumption; and a comparator for comparing the power quotient with a threshold value for the power quotient. The invention also relates to an inverter controller, an inverter, a drive, ventilation or air-conditioning system and a vehicle having a blockage detector according to the invention. In addition, the invention relates to a corresponding method for detecting a blocked state of an electrical machine.