Motor Drive DC Link Control During Instantaneous Power Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Motor drive systems face challenges in maintaining continuous operation and torque supply amidst instantaneous power interruptions and noise, particularly in railway and other industrial applications, where power supply voltage fluctuations can cause system tripping and delay in motor speed recovery.
Innovation Solution
A motor drive apparatus comprising a rectifier circuit, an inverter circuit, a control unit, and a detection unit that converts AC power to DC and manages regenerative power to maintain DC link voltage, ensuring continuous operation by calculating and outputting motor power based on target speed and detecting power supply voltage decreases, and using regenerative power to maintain voltage during interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the motor drive apparatus operates with standard power supply voltage management, then the system structure remains simple, but the system trips during instantaneous power interruptions and cannot maintain continuous operation
Solution Approach 1:
The control unit detects power supply voltage decreases in advance and switches to capacitor power supply mode before the power interruption fully impacts the motor. This preliminary detection and switching action prevents system tripping and maintains continuous operation during instantaneous power interruptions.
Solution Approach 2:
The capacitor is charged during normal operation to store energy that cushions against instantaneous power interruptions. When a voltage decrease is detected, this pre-charged capacitor provides immediate power support, acting as a buffer that prevents the motor drive system from tripping during brief power failures.
2Loss of time
If regenerative power is used to maintain DC link voltage during power interruptions, then the motor speed recovery is quick, but the control system complexity increases
Solution Approach 1:
The control unit continuously monitors the DC link voltage and motor speed, using this feedback to dynamically adjust the inverter circuit operation. When power is restored, the feedback mechanism enables the system to quickly regain target speed by optimizing the use of regenerative power from the motor, minimizing speed recovery time.
Solution Approach 2:
The motor itself serves as a power source during recovery by generating regenerative power through its inertia. The control unit enables the motor to feed this regenerative power back into the DC link, allowing the system to self-recover speed without requiring external power support during the critical recovery period.
3Productivity
If the PFC circuit operates continuously to improve power factor, then the power factor remains optimized, but the system cannot respond quickly to power supply fluctuations
Solution Approach 1:
The PFC circuit operation is dynamically adjusted based on real-time power supply conditions. During normal operation, the PFC circuit actively improves power factor. When power supply fluctuations or interruptions are detected, the control unit modifies PFC circuit operation to prioritize rapid response and stability over continuous power factor optimization, enabling adaptive behavior to varying power supply conditions.
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 system ensures uninterrupted motor operation and quick recovery of target speed after power restoration by managing power supply fluctuations, absorbing pulsations through inertia, and maintaining power factor control during normal conditions.
Implementation Method 1
a rectifier circuit that converts a power supply voltage from a single-phase or three-phase AC power supply into a DC voltage
Implementation Method 2
an inverter circuit that converts the DC voltage output from the rectifier circuit into a motor drive voltage and outputs the motor drive voltage to a motor
Implementation Method 3
maintain a voltage of a DC link connecting the rectifier circuit and the inverter circuit by using regenerative power obtained from the motor
Data Source
AI summary
A motor drive apparatus includes: a rectifier circuit that converts a power supply voltage from a single-phase or three-phase AC power supply into a DC voltage; an inverter circuit that converts the DC voltage output from the rectifier circuit into a motor drive voltage and outputs the motor drive voltage to a motor; a control unit that controls the rectifier circuit and the inverter circuit; and a detection unit that detects a decrease in the power supply voltage based on a voltage value or phase of the power supply voltage. The control unit controls the rectifier circuit and the inverter circuit to output a motor power calculated from a target speed of the motor to the motor, when a decrease in the power supply voltage is not detected. The control unit controls the inverter circuit to maintain a voltage of a DC link connecting the rectifier circuit and the inverter circuit by using regenerative power obtained from the motor, when a decrease in the power supply voltage is detected.