Submersible Pump Motor Drive Clamp Filter for Ring-Up Suppression
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Solution Overview
Problem
Existing pump systems with remotely located variable frequency drives face challenges in attenuating high voltage ring up and reflections at motor terminals, especially at long cable lengths, which can lead to surge transient weaknesses and increased power dissipation.
Innovation Solution
The proposed solution involves a pump system design that includes a motor drive with a clamp filter comprising an inductor, a resistor, and diodes, along with a surge protector and a current sense shunt resistor, to effectively attenuate high voltage ring up and reflections and improve immunity to surge transients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an LCR filter topology is used to attenuate high voltage ring up and reflections at motor terminals, then voltage attenuation is improved, but the filter becomes much more expensive and impractical due to larger components required and increased power dissipation
Solution Approach 1:
The patent extracts the capacitor component from the traditional LCR filter topology, creating a simplified LR filter design. The capacitance function is instead provided by the motor's own input capacitance, eliminating the need for large external capacitors while maintaining voltage attenuation effectiveness.
Solution Approach 2:
The patent makes the motor's input capacitance serve dual purposes: it functions as both the motor's inherent electrical property and as the filtering capacitor in the LR filter circuit. This multi-functionality eliminates the need for separate capacitor components while achieving the desired filtering effect.
2Object-affected harmful factors
If capacitor-based filter topologies are used to meet dv/dt and peak voltage targets, then voltage control is improved, but the system becomes susceptible to surge transient failures and requires expensive components
Solution Approach 1:
The patent adds a metal oxide varistor (MOV) surge protector in parallel with the LR filter circuit. This surge protector acts as a preemptive protective measure, clamping voltage spikes and absorbing surge transients before they can damage the filter components or motor, thereby enhancing system reliability.
Solution Approach 2:
The metal oxide varistor serves as an intermediary protective element between the filter circuit and surge transients. It mediates the interaction by absorbing excess energy from voltage spikes and protecting the more sensitive filter components from damage.
3Object-affected harmful factors
If capacitor-less topologies with higher reverse recovery charge diodes are used to manifest capacitance, then dv/dt and peak voltage targets are met, but power dissipation increases due to greater reverse recovery losses
Solution Approach 1:
The patent removes the need for special high reverse recovery charge diodes by extracting the capacitance function from the diode selection criteria. Instead, capacitance is provided by the motor's input capacitance, allowing the use of standard diodes with lower reverse recovery losses, thereby reducing power dissipation.
4Stability of the object's composition
If damping resistors are added to filter topologies to provide damping, then filter performance is improved, but the diodes remain highly susceptible to failure due to surge transients
Solution Approach 1:
The patent places the metal oxide varistor surge protector in parallel with the LR filter circuit, providing preemptive protection against surge transients. This protective measure is implemented regardless of the presence of damping resistors, ensuring diode reliability by clamping voltage spikes before they can cause damage.
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
This design effectively reduces high voltage stress on motor windings, minimizes ball bearing wear due to dv/dt capacitive currents, and enhances the system's immunity to surge transients, while also reducing costs associated with motor drive electronics.
Implementation Method 1
a rectifier coupled to the power source and configured to convert alternating current ('AC') voltage from the power source into a direct current ('DC') output voltage
Implementation Method 2
an inverter coupled to the rectifier and configured to convert the DC output voltage of the rectifier into an approximated AC output voltage
Implementation Method 3
a resistor, the resistor having an input side connected to an output side of the inductor and an output side connected to the cathode of the first diode and the anode of the second diode
Implementation Method 4
an inductor, the inductor having an input side connected to the AC output voltage and an output side connected to an input side of the resistor
Data Source
AI summary
A clamp filter is provided for attenuating high voltage ring up and reflections in an output of a variable frequency drive for deep well pump applications where an output of the variable frequency drive is connected to a remote pump motor by a cable. The filter includes an inductor, a resistor, a first diode and a second diode. The inductor has an input side connected to an AC output voltage of an inverter and an output side connected to an input side of the resistor. The resistor has an output side connected to a cathode of the first diode and an anode of the second diode. An anode of the first diode is connected to a common point, and a cathode of the second diode is connected to a +DC line.