Dual-Motor Sensorless Control Under Inverter Noise Constraints
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In heat pump type refrigeration apparatuses and water heaters, noise in inverter current and voltage detection values due to large current operations hinders rotor position estimation and motor control, particularly affecting brushless DC motors, and existing solutions do not adequately address the impact on outdoor fan motors during compressor motor operations.
Innovation Solution
A motor control device that uses rotor position sensorless control for both motors, avoids starting the second motor during large current operations of the first motor, and includes a determination unit to cancel abnormality detections caused by noise, preventing unnecessary shutdowns and ensuring stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If rotor position sensorless control is used for both motors, then control simplicity is improved, but startup abnormality occurs due to noise during large current operations
Solution Approach 1:
The control unit checks whether a large current operation is being performed before allowing startup of the second motor. This preliminary check prevents startup abnormalities by avoiding simultaneous operation during noisy conditions, thereby maintaining reliability while keeping the sensorless control system simple
2Power
If large current flows through the first motor, then driving force is improved, but noise is added to detection values hindering rotor position estimation
Solution Approach 1:
The system extracts and identifies the noise component in the detection values during large current operations. By separating the noise from the valid signal, the control unit can accurately estimate rotor position even when the first motor is performing high-power operations
3Reliability
If the determination unit detects abnormality during large current operations, then abnormality detection capability is improved, but false abnormality detection occurs due to noise
Solution Approach 1:
The control unit checks whether a large current operation is being performed before acting on abnormality detection results. This preliminary check prevents false shutdowns by identifying when detected abnormalities are actually just noise from high-power operation, thereby maintaining both detection capability and operational continuity
Data Source
AI summary
A motor control device is configured to drive a first motor that rotates a first rotation body and a second motor that rotates a second rotation body. The motor control device includes a power supply unit, inverters configured to convert an output from the power supply unit to an alternating current and supply the output to the first motor and the second motor, and a control unit configured to drive the second motor using rotor position sensorless control. The control unit may be configured to not start up the second motor during a predetermined operation in which a large current flowing through the first motor is being performed.