Inverter device and outdoor unit of heat pump device
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Solution Overview
Problem
Inverter devices struggle to maintain performance at ambient temperatures lower than their operation guarantee temperature, leading to reduced performance and potential failure, especially in cold regions, without the addition of costly heating elements.
Innovation Solution
An inverter device with a temperature sensor and control unit that forces current through the DC link to generate heat, maintaining operational temperatures through electrical losses and controlled heating operations, even when the ambient temperature is below the guarantee threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a heating element is added to warm up the inverter device at low temperatures, then the performance can be maintained, but the number of parts and cost increase
Solution Approach 1:
The inverter device uses its own inverter circuit to generate heat for warming up, rather than requiring an external heating element. The control unit controls the inverter circuit to operate in a state that generates heat, allowing the device to warm itself using its existing components.
Solution Approach 2:
The inverter circuit is made to serve dual purposes: normal operation and heating/warming up. By controlling the inverter circuit to operate in a heat-generating state, the same circuit performs both its primary function and the additional function of warming up the device, eliminating the need for a dedicated heating element.
2Adaptability or versatility
If the inverter device operates below the guaranteed temperature range, then it can start up in cold regions, but performance cannot be guaranteed
Solution Approach 1:
The control unit detects low temperature conditions and initiates a warming-up operation before normal operation begins. By pre-warming the inverter device using the inverter circuit itself, the device ensures it reaches the guaranteed temperature range before attempting normal operation, thus maintaining performance guarantees in cold regions.
Solution Approach 2:
The control unit changes the operating parameters of the inverter circuit to a heat-generating state during the warming-up phase. This parameter change allows the device to raise its temperature to within the guaranteed operating range, ensuring both adaptability to cold environments and maintenance of performance guarantees.
3Device complexity
If electrical loss is used to generate heat for warming up, then no additional parts are needed, but energy is consumed
Solution Approach 1:
The control unit intentionally allows electrical loss in the inverter circuit to be converted into useful heat for warming up the device. What would normally be wasted energy (electrical loss) is harnessed to achieve the beneficial effect of warming up the inverter device, eliminating the need for additional heating components.
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
Ensures the inverter device operates within its guaranteed temperature range, maintaining performance and extending its usability in low-temperature environments without increasing the number of parts or costs.
Implementation Method 1
causes electrical loss (e.g., at least loss by an internal resistor of a soothing capacitor) by forcefully passing a current through the DC link... the inverter device can be warmed up by heat generation resulting from the electrical loss
Implementation Method 2
the heating operation may be performed by the control unit causing switching loss in the inverter circuit by allowing a pulse current to repeatedly and alternately flow through a coil of the motor
Data Source
AI summary
An inverter device converts DC to AC and supplies power to a load (motor), and includes a temperature sensor that directly or indirectly detects a temperature of the inverter device; a DC link including a smoothing capacitor; an inverter circuit provided between the DC link and the load (motor); and a control unit that controls the inverter circuit. The control unit forcefully passes a current through the DC link when an instruction to allow the inverter circuit to operate is not received and when the temperature detected by the temperature sensor is less than or equal to a predetermined temperature.