Three-Phase Inverter Control for Uniform Compressor Heating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing heating methods for compressors in heat pump devices face challenges such as non-uniform heating due to open-phase currents, difficulty in maintaining required heating levels, and limitations in high-frequency operation, which result in inefficiencies and noise generation.
Innovation Solution
A heat pump device configuration that includes a compressor, a three-phase inverter with parallel-connected switching elements, and a control unit that generates high-frequency AC voltage by correcting voltage command values based on detected voltages and switching between phases, ensuring uniform heating and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If open-phase current is caused to flow to warm the motor winding, then the compressor can be heated, but the heating is non-uniform and the compressor cannot be uniformly heated
Solution Approach 1:
The patent segments the heating process by applying high-frequency voltage to each phase winding separately through the three-phase inverter, ensuring all windings are uniformly heated rather than relying on open-phase current which only heats specific phases
Solution Approach 2:
The patent changes the voltage frequency parameter to high-frequency (several kHz or higher) to generate sufficient iron loss and ohmic loss for uniform heating of the motor winding, resolving the non-uniform heating issue
2Use of energy by moving object
If high-frequency operation is implemented to improve heating efficiency, then power efficiency is improved, but noise is generated and system speed-up is required
Solution Approach 1:
The patent applies periodic high-frequency voltage through the three-phase inverter to generate continuous iron loss and ohmic loss for heating, achieving efficient heating without requiring mechanical speed-up of the system
Solution Approach 2:
The patent replaces mechanical heating methods with electromagnetic heating by applying high-frequency voltage, eliminating the need for mechanical speed-up while achieving efficient heating
3Temperature
If the current flowing to the winding is increased to maintain heating, then heating efficiency is improved, but the current value becomes difficult to maintain and required heating may not be secured
Solution Approach 1:
The patent uses a voltage command correction unit that detects the actual voltage and corrects the voltage command value to maintain stable high-frequency voltage output, ensuring reliable and maintainable heating current
Solution Approach 2:
The patent changes the voltage command value dynamically based on detected voltage to maintain stable current flow, ensuring the required heating amount is consistently achieved
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
The solution enables efficient heating of refrigerant in compressors, preventing breakage and improving power efficiency while minimizing noise and power consumption.
Implementation Method 1
heat generation due to ohmic loss
Implementation Method 2
heat generation due to hysteresis loss
Data Source
AI summary
A voltage-command correction-value computation unit outputs a correction value for correcting a voltage command value according to a bus voltage. A multiplier calculates a voltage command value acquired by correcting the voltage command value based on the correction value. A voltage-command generation unit generates and outputs three-phase voltage command values based on the corrected voltage command value calculated by the multiplier and a phase. A PWM-signal generation unit generates six drive signals corresponding to switching elements of an inverter based on the three-phase voltage command values outputted by the voltage-command generation unit and a carrier signal. The PWM-signal generation unit outputs the generated drive signals to the corresponding switching elements of the three-phase inverter, to cause the inerter to generate a high-frequency AC voltage.