Scroll Compressor Inverter Deceleration Control
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Solution Overview
Problem
Existing scroll compressors experience noise due to reverse rotation of the orbiting scroll when stopping, and the use of check valves to prevent backflow complicates control and increases costs.
Innovation Solution
A scroll compressor with an inverter-controlled motor that decelerates in two steps, a first deceleration when stopping compression and a second, slower deceleration until the compressor stops, to prevent reverse rotation and backflow without additional devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a check valve is provided to prevent backflow of compressed air, then reverse rotation of the orbiting scroll is prevented, but control becomes complicated and the price increases
Solution Approach 1:
The patent replaces the mechanical check valve system with an inverter-based motor control system. The inverter controls the rotational speed of the motor driving the orbiting scroll, preventing reverse rotation through electronic control rather than mechanical means. This substitution eliminates the need for check valves and associated complex control mechanisms, reducing overall device complexity while maintaining reliability.
Solution Approach 2:
The patent utilizes parameter changes by controlling the rotational speed of the motor through the inverter. By adjusting the speed parameter of the motor, the system prevents the orbiting scroll from rotating in reverse during compression and stopping phases. This parameter-based control approach replaces the need for mechanical check valves and simplifies the overall system architecture.
2Device complexity
If the inverter controls motor speed in two steps, then reverse rotation is prevented without additional devices, but the deceleration control becomes more complex
Solution Approach 1:
The patent applies dynamics by implementing a two-step deceleration control strategy. During the first step, the inverter controls the motor to decelerate at a first deceleration rate when the stop command is issued and compression is ongoing. During the second step, when compression stops, the inverter switches to a second deceleration rate (lower than the first) to bring the motor to a complete stop. This dynamic, phase-based control prevents reverse rotation while maintaining system simplicity.
Solution Approach 2:
The inverter performs preliminary action by controlling the deceleration profile before the motor comes to a stop. By pre-planning the two-step deceleration sequence based on the compression state, the system prevents reverse rotation from occurring in the first place, rather than correcting it after it happens. This proactive control approach simplifies the overall system design.
Data Source
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AI summary
An object of the present invention is to provide a scroll compressor with a simple configuration which is capable of preventing the occurrence of noise induced due to compressed air remaining in a discharge pipe flow backward and an orbiting scroll rotating reversely when stopping the compressor. To this end, there is provided a scroll compressor including a scroll type compressor body provided with an orbiting scroll and a fixed scroll; a motor that drives the compressor body; an inverter that drives the motor; a discharge pipe that connects a discharge port of the compressor body to an air tank storing air compressed by the compressor body; and a check valve that shuts off the compressed air flowing backward from the air tank in the discharge pipe, in which, when stopping the compressor body, the inverter controls a rotational speed of the motor driving the compressor body, in two steps at a first deceleration and a second deceleration lower than the first deceleration, from when a stop command is output until the compressor body stops.