Topology of converter power supplies in electrical climate compressors
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Solution Overview
Problem
The existing control devices for electric compressors in motor vehicles face issues with electromagnetic compatibility (EMC) due to interference signals transmitted between the high-voltage and low-voltage domains through the use of flyback transformers, which cause parasitic coupling and require complex countermeasures.
Innovation Solution
The control device employs galvanically isolated voltage supplies for both domains, eliminating the need for flyback transformers and using a switching regulator with pulse width modulation (PWM) control, along with a start-up unit, discharge unit, and overvoltage unit to manage voltage and prevent interference, ensuring reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a flyback transformer is used to bridge the insulation barrier between high-voltage and low-voltage domains, then voltage transmission is achieved, but switching interferences and EMC interference signals are transmitted between domains
Solution Approach 1:
The patent divides the voltage supply system into two completely separate and isolated voltage domains: a high-voltage domain with its own voltage supply connected to the high-voltage battery, and a low-voltage domain with its own voltage supply connected to the vehicle battery. This segmentation eliminates the need for a flyback transformer to bridge the domains, thereby preventing switching interferences and EMC interference signals from being transmitted between domains while maintaining independent voltage transmission capability in each domain.
Solution Approach 2:
The patent extracts and removes the flyback transformer from the system architecture. By eliminating this component that caused parasitic coupling capacitance and interference transmission, the system achieves better EMC performance. The voltage transmission function previously performed by the flyback transformer is replaced by domain-isolated voltage supplies that do not create interference pathways.
2Power
If a flyback transformer is used to supply voltage across the insulation barrier, then voltage transmission is achieved, but complex EMC countermeasures are required
Solution Approach 1:
By segmenting the voltage supply into two isolated domains, each with its own voltage supply unit, the patent eliminates the need for complex EMC countermeasures. The segmentation prevents interference generation at the source rather than requiring additional filtering or shielding components, thereby reducing overall system complexity while maintaining voltage transmission functionality.
3Object-affected harmful factors
If galvanically isolated voltage supplies are used for high-voltage and low-voltage domains, then EMC is improved by preventing interference, but the system requires separate voltage supply units for each domain
Solution Approach 1:
The patent extracts the problematic coupling element (flyback transformer) and replaces it with independent voltage supply units for each domain. While this increases the number of supply units, it eliminates the need for complex EMC countermeasures and interference filtering, resulting in a cleaner overall system architecture with better EMC performance.
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 configuration significantly improves EMC by preventing interference between the high-voltage and low-voltage domains, allowing for more reliable and interference-free operation of the electric compressor.
Implementation Method 1
The second voltage supply comprises a switching regulator with a pulse width modulation (PWM) control
Implementation Method 2
The microcontroller 8 in the low-voltage domain 11 and the microcontroller 10 in the high-voltage domain 12 communicate across an optocoupler 9
Implementation Method 3
The microcontroller 10 in the high-voltage domain 12 is supplied with voltage from the low-voltage source 14 across a flyback transformer 15
Data Source
AI summary
The invention relates to an electric compressor control device comprising a low-voltage domain. The low-voltage domain comprises a first control unit set up to process control commands for the control of the electric compressor, and a first voltage supply set up to supply the first control unit and connected to a low-voltage source. The low-voltage domain comprises furthermore a high-voltage domain. The high-voltage domain comprises a second control unit set up to control a power output stage, wherein the power output state inverts a dc voltage from a high-voltage source into an ac voltage in order to supply a motor of the electric compressor with the ac voltage. The high-voltage domain comprises furthermore a second voltage supply set up to supply the second control unit and connected to the high-voltage source.