Heat pump device, air conditioner, and freezer
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Solution Overview
Problem
Existing heat pump devices face inefficiencies in heating the compressor, leading to refrigerant stagnation and increased power consumption, as they rely on high-frequency low voltage and DC current preheating methods that do not accurately detect refrigerant state, resulting in inadequate heat generation and potential compressor failure.
Innovation Solution
A heat pump device with an inverter control unit that applies a high-frequency voltage to the compressor motor based on temperature sensors' readings, determining the amplitude and phase of the voltage command to efficiently heat the compressor and prevent refrigerant stagnation, using a three-phase motor and silicon carbide switching elements to enhance heating efficiency and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high-frequency low voltage is applied to the compressor during shutdown to improve rising speed, then the compressor heating effect is improved, but the heating stability is insufficient due to rotor stop position variations
Solution Approach 1:
The patent applies dynamic control by switching between different voltage frequencies based on operational requirements. During shutdown, high-frequency voltage is applied for rapid heating, while during operation, normal frequency maintains stable compression. This dynamic switching resolves the contradiction between rapid heating and stable operation.
Solution Approach 2:
The patent changes the voltage frequency parameter from normal operating frequency to high-frequency during shutdown conditions. This parameter change enables the compressor to receive adequate heating during idle periods without affecting normal compression performance, thereby resolving the heating stability issue.
2Temperature
If locked energization is used to heat the compressor during shutdown, then the compressor is preheated effectively, but power consumption increases continuously
Solution Approach 1:
Instead of continuous locked energization, the patent implements periodic high-frequency voltage application during shutdown periods. This periodic action provides necessary heating while allowing energy-saving intervals, thereby reducing overall power consumption compared to continuous heating methods.
Solution Approach 2:
The patent applies high-frequency voltage during shutdown periods as a preliminary heating action before normal operation begins. This preliminary heating prevents refrigerant stagnation and ensures ready-to-start conditions without requiring continuous energy input, thus reducing overall power consumption.
3Object-affected harmful factors
If high-frequency single-phase AC power supply is used to heat the compressor, then noise is reduced and vibration is suppressed, but heating efficiency deteriorates due to fast current decay during off-period
Solution Approach 1:
The patent ensures continuous useful action by applying high-frequency voltage specifically during shutdown periods when the compressor is idle. During these periods, continuous heating is required without the need for rapid current decay that occurs during operational PWM cycles. This timing strategy maintains heating efficiency while still achieving noise and vibration reduction benefits.
Solution Approach 2:
The patent dynamically adjusts the voltage application strategy based on operational state. During shutdown, high-frequency voltage is applied continuously for effective heating. During operation, normal frequency is used with PWM control. This dynamic adaptation resolves the contradiction between noise reduction and heating efficiency.
4Temperature
If DC current is applied to the motor winding for preheating, then the compressor is heated, but inverter loss increases and reliability decreases
Solution Approach 1:
The patent replaces the conventional DC current-based heating method with high-frequency AC voltage application. This substitution eliminates the need for DC injection circuits and associated inverter losses, while achieving effective compressor heating through high-frequency electromagnetic induction in the motor windings, thereby improving system reliability.
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 stably and efficiently heats the compressor, preventing refrigerant stagnation, reducing energy consumption, and improving reliability by accurately detecting the refrigerant state and adjusting heating output, while minimizing noise and inverter losses.
Implementation Method 1
the inverter control unit determines an amplitude and a phase of a voltage command for generating the high-frequency voltage... efficiently heat the compressor
Data Source
AI summary
A heat pump device includes: a compressor including a compression mechanism compressing a refrigerant and a motor driving the compression mechanism; an inverter unit applying a voltage for driving the motor; an inverter control unit generating a driving signal for driving the inverter unit; and temperature sensors detecting temperatures of the compressor, wherein the inverter control unit includes a normal operation mode in which a refrigerant is compressed by performing a normal operation of the compressor and a heating operation mode in which a heating operation of the compressor is performed by applying, to the motor, a high-frequency voltage, and in the heating operation mode, the inverter control unit determines an amplitude and a phase of a voltage command for generating the high-frequency voltage on a basis of a temperatures detected by the temperature sensors and a necessary amount of heat specified in advance.