PMSM Control Circuit for Load-Adaptive Washing Machine Start-Up
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Solution Overview
Problem
Permanent magnet synchronous motors in washing machines experience excessive energy consumption and reduced lifespan due to hard start-ups and unnecessary current delivery during frequent stop-start operations, which are not efficiently managed by existing control methods.
Innovation Solution
A control circuit utilizing a microcontroller to implement field-oriented control, separating motor currents into torque and flux components, and adjusting current values based on measured load conditions to minimize start-up currents and optimize energy usage, preventing hard start-ups and overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If maximum start current is applied at every start-stop operation, then the motor can start up at maximum load, but energy consumption increases and the motor overheats due to excessive current delivery
Solution Approach 1:
The control circuit dynamically adjusts the start current based on the actual load conditions detected during each startup event. Instead of applying a fixed maximum current, the system modifies the current magnitude according to the measured load, enabling reliable startup while preventing excessive current delivery and energy waste.
Solution Approach 2:
The control circuit incorporates feedback mechanisms that monitor motor performance and load conditions during startup operations. This feedback enables the system to adjust the start current in real-time, ensuring sufficient current for startup while avoiding unnecessary energy consumption and overheating from excessive current delivery.
2Reliability
If maximum start current is applied at every start-stop operation, then the motor can start up at maximum load, but the working life of the motor decreases due to overheating in hard start-ups
Solution Approach 1:
The control circuit dynamically adjusts the start current based on the actual load conditions detected during each startup event. Instead of applying a fixed maximum current, the system modifies the current magnitude according to the measured load, enabling reliable startup while preventing excessive current delivery and energy waste.
Solution Approach 2:
The control circuit prepares for potential overheating by implementing current limiting measures before they become problematic. By detecting load conditions in advance and adjusting the start current accordingly, the system prevents hard start-ups that would cause overheating and extend motor working life.
3Reliability
If constant torque current is applied regardless of laundry load, then the motor can start up at maximum load, but excessive current is delivered unnecessarily when load is less than maximum
Solution Approach 1:
The control circuit changes the current parameter based on the detected load conditions. Instead of maintaining a constant torque current, the system adjusts the current magnitude to match the actual laundry load, ensuring sufficient current for startup while avoiding excessive current delivery when the load is less than maximum.
Solution Approach 2:
The control circuit applies different current levels to different load conditions. Instead of a uniform constant torque current, the system tailors the current delivery to the specific load present, providing maximum current only when necessary and reducing current when the load is lighter, thereby eliminating unnecessary energy loss.
Data Source
Figure 1
Figure 2~3
AI summary
The present invention relates to a control circuit (1) that controls the permanent magnet synchronous motor (M) used in driving the drum in washing machines, that comprises a converter (2) that converts AC mains voltage to DC voltage, a three-phase inverter (3) that inverts the direct current received from the converter (2) to three phase current (la, lb, lc), a speed and position estimator (4) that detects the data relating to position and speed of rotor by means of voltage sensors during start up and operation of the motor (M) and a microcontroller (5) that provides control of the motor (M) by sending sinusoidal switching signals to the three-phase inverter (3) with the signals received from the speed and position estimator (4).