Heat Pump Inverter Current Filtering for Compressor Heating Protection
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Solution Overview
Problem
Existing heating techniques for compressors in heat pump devices that use high-frequency AC voltage to prevent motor and inverter damage from large currents are ineffective due to noise interference, leading to potential damage despite high current detection.
Innovation Solution
A heat pump device with a current detection unit that filters out high-frequency noise from current values and a drive-signal stop unit that halts voltage output when current exceeds a predetermined level, ensuring the motor and inverter are protected from excessive currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high-frequency AC voltage is supplied to the compressor for heating, then the compressor can be kept warm and lubricating action facilitated, but the current detection system fails to detect the large current due to noise, leading to potential motor and inverter damage
Solution Approach 1:
A current detection unit is introduced as an intermediary component between the inverter and the control system. This unit specifically detects current flowing through the inverter and provides accurate feedback signals to the inverter control unit, enabling reliable detection of large currents during high-frequency heating operations without being affected by noise interference
Solution Approach 2:
The system implements a feedback mechanism where the current detection unit continuously monitors current flow and feeds this information back to the inverter control unit. When the feedback signal indicates current exceeds a predetermined threshold, the control unit automatically stops voltage application, preventing motor and inverter damage while maintaining safe heating operations
2Ease of operation
If high-frequency AC voltage is applied to the compressor, then lubricating action is improved, but the current value is removed as noise by the detection system, preventing proper protection
Solution Approach 1:
The current detection unit serves as a specialized intermediary that accurately measures current flow during high-frequency operations. It is positioned to directly monitor inverter current and provide clean, noise-free detection signals to the control system, ensuring measurement precision is maintained even when high-frequency voltage is applied for lubricating action
Solution Approach 2:
The system changes the detection parameters by using a dedicated current detection unit that is specifically tuned to detect current flow characteristics during high-frequency heating. This detection unit provides accurate current value feedback even when the voltage frequency is high, preventing the current signal from being removed as noise
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
Effectively prevents motor and inverter damage by accurately detecting large currents and stopping voltage application, thereby ensuring reliable operation and extending the lifespan of components.
Implementation Method 1
an inverter that applies a predetermined voltage to the motor
Implementation Method 2
a current detection unit that detects a current value flowing in the inverter
Implementation Method 3
when the current value output from the current detection unit is equal to or larger than a predetermined current value, stops an output of a drive signal from the inverter control unit to the inverter
Data Source
AI summary
A heat pump device includes an inverter control unit outputting PWM signals to an inverter; a current detection unit detecting a current value flowing in the inverter and outputting the current value after reducing a current value having a first frequency or higher in detected current value; and a drive-signal stop unit that, when the current value output from the current detection unit is equal to or larger than an interruption level, stops output of PWM signals to the inverter. Particularly, the inverter control unit generates a voltage command value such that the voltage command value becomes a value equal to or larger than a lower limit determined according to the first frequency and generates PWM signals based on generated voltage command value and a carrier signal, thereby causing a voltage output time to the motor to be a predetermined time or longer.