Drive Circuit Ride-Through Using Capacitor Backup During Voltage Sags
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Solution Overview
Problem
Disruptions in line voltage to electrical drives, such as those used in submersible pumps, can cause operational shutdowns and require difficult restarts, leading to decreased production efficiency and potential damage due to sediment accumulation.
Innovation Solution
An electrical ride-through (ERT) unit is configured with an energy storage section and output diode to selectively store and discharge energy, ensuring continued power supply to the drive system during voltage disruptions by preventing current flow during normal operation and allowing it during voltage drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drive system is connected directly to the electrical grid without energy storage, then the device complexity is low, but the reliability decreases during voltage disruptions
Solution Approach 1:
The energy storage section is pre-charged to a voltage level higher than the DC bus voltage before any disruption occurs. This preliminary charging ensures that when a voltage disruption or sag happens, the storage section can immediately begin discharging to support the DC bus voltage, maintaining operational continuity without requiring complex real-time control decisions.
Solution Approach 2:
The energy storage section acts as an intermediary component between the electrical grid and the drive system. It buffers voltage disruptions by absorbing or supplying energy as needed, isolating the drive system from grid fluctuations. The output diode further mediates the current flow direction, ensuring unidirectional power flow from storage to DC bus during disruptions.
2Reliability
If the energy storage section continuously supplies power to the drive circuit, then the reliability during voltage disruption is improved, but the loss of energy increases during normal operation
Solution Approach 1:
The system dynamically adjusts the energy flow based on real-time voltage conditions. During normal operation, the output diode blocks current flow from the storage section to the DC bus, preventing continuous energy discharge. During voltage disruptions or sags, the diode automatically permits current flow from storage to DC bus, providing support only when needed. This dynamic behavior minimizes energy loss while maintaining reliability.
3Productivity
If the drive system lacks voltage support during disruption, then the device complexity is low, but the productivity decreases due to shutdowns and restarts
Solution Approach 1:
The energy storage section enables continuous operation of the drive system during voltage disruptions by providing supplemental power. This continuity prevents shutdowns that would otherwise occur during voltage sags or outages, eliminating productivity losses associated with stopping and restarting equipment. The storage section maintains the DC bus voltage within operational limits, allowing the motor drive to continue functioning.
4Adaptability or versatility
If the output diode permits bidirectional current flow, then the adaptability is improved, but the loss of energy increases due to reverse current
Solution Approach 1:
The output diode extracts and eliminates the problematic reverse current flow capability from the circuit. By implementing unidirectional current flow, the diode prevents energy loss while maintaining sufficient adaptability for the intended application. The diode's one-way conduction characteristic blocks reverse current from flowing back into the storage section, eliminating a source of energy loss while still allowing the system to respond to voltage disruptions effectively.
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 ERT unit maintains operational continuity and reduces the need for costly and risky restarts by providing stable power during voltage disruptions, minimizing downtime and preventing damage from sediment accumulation.
Implementation Method 1
The storage section can be configured to selectively store and discharge energy
Implementation Method 2
The output diode can be configured to prevent electrical current from flowing from the storage section to the drive circuit when a voltage level on the drive circuit is greater than the voltage level of the storage section
Data Source
AI summary
An electrical ride-through (ERT) unit is configured to apply a voltage to a drive circuit during disruptions of line voltage to the drive circuit. The ERT unit includes a capacitor on an ERT circuit that is prevented from applying the voltage to the drive circuit during normal operation of the drive circuit and applies the voltage to the drive circuit during a voltage drop on the drive circuit.