Motor Drive Power Limiting Using Voltage and Current Detection
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Solution Overview
Problem
Existing motor control devices struggle to accurately detect load conditions when the motor voltage can be varied, leading to inadequate power limitation of the drive circuit.
Innovation Solution
A motor control device that includes a voltage detection part, a current detection part, and a power limitation part to accurately detect load power based on load voltage and current, and adjust the rotation command value accordingly to perform power limitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If load detection is performed based on motor current only, then the control method is simple, but the load detection accuracy deteriorates when motor voltage varies
Solution Approach 1:
The patent introduces voltage detection as an intermediary measurement to complement current detection. By adding voltage detection part (2a) that measures the voltage applied to the motor, the system obtains complete information (voltage and current) needed for accurate power calculation, resolving the inaccuracy caused by voltage variation while maintaining a relatively simple control structure
Solution Approach 2:
The patent changes the detection parameters from current-only to both voltage and current. The power limitation part (1b) calculates load power by combining voltage detected by voltage detection part (2a) and current detected by current detection part (2b), enabling accurate load detection even when voltage varies during operation
2Productivity
If power limitation is not performed, then the motor can operate at full capacity, but the drive circuit may be damaged by overload
Solution Approach 1:
The patent implements a feedback control mechanism where the power limitation part (1b) continuously monitors the calculated load power and compares it with the upper limit value. When load power exceeds the limit, the system automatically decreases the rotation command value (Ra) to reduce power consumption, preventing drive circuit damage while maintaining optimal motor operation within safe limits
Solution Approach 2:
The patent introduces dynamic power limitation that adjusts the rotation command value based on real-time load power conditions. The power limitation part (1b) dynamically modifies the rotation command value (Ra) downward when power limits are exceeded and can increase it when power is below the lower limit, enabling the motor to operate at full capacity when safe and limit power when necessary to protect the drive circuit
Data Source
AI summary
A motor control device and a motor control method capable of performing power limitation of a drive circuit more accurately are provided. A motor control device for controlling a motor by supplying a drive signal generated on the basis of a rotation command value by a drive circuit to the motor includes a voltage detection part that detects a voltage of the drive signal as a load voltage, a current detection part that detects a current of the drive signal as a load current, and a power limitation part that detects a load power of the drive circuit on the basis of the load voltage and the load current, and decreases the rotation command value when the load power exceeds a predetermined upper limit value to perform power limitation.