Motor Control Device Power Hold Time Extension
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Solution Overview
Problem
Conventional motor control devices face challenges in securing sufficient power to retract driven objects and stop motors without interference when power fails, especially in systems where the cost of uninterruptible power sources is high, and smoothing capacitors provide insufficient power to support peripherals like fans and monitors.
Innovation Solution
A motor control device that includes a current value sampling unit, motor sampling unit, driven object sampling unit, PWM signal generation unit, and operation stop unit, which adjust sampling periods and carrier frequencies based on stored power in a DC link to optimize power usage and extend output hold time during power failures, allowing for safe retraction and stopping of motors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a smoothing capacitor is used in the control power source to secure power when power fails, then the cost of the system is reduced compared to using an uninterruptible power source, but the power that can be secured when power fails is insufficient to support both the motor control device and peripheral devices
Solution Approach 1:
The patent implements dynamic power management by adjusting the sampling period of the motor based on the remaining power in the control power source. When power becomes insufficient, the system transitions from normal operation to power-saving mode by increasing the sampling period, thereby reducing power consumption while maintaining essential control functions
Solution Approach 2:
The patent changes the sampling period parameter dynamically based on power availability. By increasing the sampling period from a normal value to an extended value when power fails, the system reduces power consumption to match the limited power available from the smoothing capacitor, enabling continued operation of essential functions
2Adaptability or versatility
If power is supplied to peripheral devices (motor cooling fan, monitor) in addition to the motor control device, then the system functionality is improved, but the power secured when power fails becomes insufficient for both
Solution Approach 1:
The patent applies partial action by maintaining essential control functions while reducing or stopping non-essential peripheral functions when power fails. The motor control device continues to operate with extended sampling periods, while peripheral devices are stopped to conserve power for essential operations
Solution Approach 2:
The patent extracts essential functions from the complete system operation and prioritizes them when power fails. By separating essential motor control functions from non-essential peripheral functions, the system can maintain critical operations with limited power while stopping optional features
3Duration of action of moving object
If the sampling period is extended to reduce power consumption, then the power hold time is extended, but the control precision and response speed may be degraded
Solution Approach 1:
The patent dynamically adjusts the sampling period based on power availability rather than using a fixed extended period. This allows the system to maintain normal sampling rates when power is sufficient, preserving control precision, and only extend the sampling period when absolutely necessary to extend power hold time
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
The solution effectively extends the output hold time of the control power source, enabling safe retraction and stopping of motors even when power is limited, without increasing the capacitance of smoothing capacitors, thus reducing system costs and ensuring operational safety.
Implementation Method 1
power stored in a DC link part connected to an alternating-current power source via a converter
Data Source
AI summary
A PWM signal generation unit generates a PWM signal to drive a motor, based on a current value of the motor sampled by a current value sampling unit, a position or speed of the motor sampled by a motor sampling unit, and a position or speed of a driven object sampled by a driven object sampling unit. An operation stop unit stops the operation of any one of the motor sampling unit and the driven object sampling unit depending on the power stored in the DC link part and power to which the control power source can supply when the alternating-current power source fails.