Method for operating an electric motor coolant compressor
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Solution Overview
Problem
Existing motor vehicle refrigerant compressors lack effective methods to detect mechanical malfunctions and prevent overloading, which can lead to safety issues and increased manufacturing costs.
Innovation Solution
A method utilizing a power semiconductor switch with pulse width modulation (PWM) and a theoretical model to measure and compare temperatures, detecting deviations that indicate potential malfunctions, and reducing power output or shutting down the electric motor to prevent thermal damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature monitoring is implemented using additional temperature sensors, then reliability is improved, but device complexity and manufacturing costs increase
Solution Approach 1:
The power semiconductor switch monitors its own temperature by measuring its own on-state voltage, eliminating the need for external temperature sensors. The control unit uses the measured on-state voltage to detect temperature changes and identify malfunctioning switches, allowing the system to self-diagnose faults without additional monitoring components.
Solution Approach 2:
The on-state voltage of the power semiconductor switch serves as an intermediary parameter that indirectly indicates temperature conditions. Instead of directly measuring temperature with sensors, the system measures the on-state voltage which changes with temperature, providing a cost-effective indirect measurement method.
2Reliability
If continuous temperature monitoring is implemented, then reliability is improved, but use of energy increases
Solution Approach 1:
The temperature monitoring is performed continuously during normal compressor operation without requiring separate measurement cycles. The on-state voltage is measured throughout the PWM switching process, providing continuous temperature information while utilizing the existing operational energy of the compressor motor.
Solution Approach 2:
The power semiconductor switch provides its own temperature information through its inherent electrical characteristics during normal operation, eliminating the need for separate active sensing systems that would consume additional energy.
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 method allows for early detection of mechanical issues, preventing total compressor failure and thermal damage, while reducing manufacturing costs by eliminating the need for additional temperature sensors and ensuring safety through controlled power reduction.
Implementation Method 1
The power semiconductor is in this case provided and set up to carry, preferably to switch, an electrical current of at least 1 A
Implementation Method 2
a first temperature of the power semiconductor is measured, in particular by means of the temperature sensor
Implementation Method 3
a second temperature of the power semiconductor is determined using a theoretical model of the motor-driven refrigerant compressor, for example using a theoretical model of its electric motor, wherein in particular an operating time, an applied electrical voltage, a switched electric current
Implementation Method 4
The refrigerant compressor is usually driven by a belt drive from an internal combustion engine of the motor vehicle and has a compressor head, which is, for example, a scroll compressor head
Implementation Method 5
The refrigerant is conveyed to the condenser, which is in thermal contact with an environment of the motor vehicle. Here, there is a temperature reduction of the refrigerant
Implementation Method 6
whose pressure is in turn reduced to the original pressure in the downstream evaporator, which is why the temperature of the refrigerant is further reduced
Implementation Method 7
In the downstream heat exchanger, thermal energy is transferred from the component, thermally contacted with the heat exchanger, to the refrigerant, resulting in a cooling of the component
Data Source
AI summary
A method for operating an electric motor-driven refrigerant compressor of a motor vehicle is provided. A first temperature of a power semiconductor is measured, and a second temperature of the power semiconductor is determined using a theoretical model of the motor-driven refrigerant compressor. A difference between the first temperature and second temperature is determined. A fault is detected if the difference is greater than a first threshold. The invention further relates to a motor-driven refrigerant compressor of a motor vehicle, to the use of a motor-driven refrigerant compressor, and to a motor vehicle comprising a refrigerant circuit.