Servo DC Feeder Notch Filtering for Bus Voltage Oscillation
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Solution Overview
Problem
In servo DC feeder systems, oscillating voltages across the power feeding path occur due to interference between the LC circuit at the DC bus and the inverter circuit in the motor controller, leading to instability.
Innovation Solution
Incorporating a current control loop with a notch filter in each motor controller to control the current flowing through the servomotor, with the notch filter's center frequency corresponding to the oscillating voltage frequency, stabilizing the transfer function and reducing oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a DC power supply with a DC bus is used to feed power to multiple motor controllers, then the system structure is simplified and noise radiation is reduced, but oscillating voltage occurs across the DC bus due to interference between the LC circuit and inverter circuit
Solution Approach 1:
A damping control system is introduced as an intermediary between the power supply and motor controllers. This control system includes a damping controller that generates damping control signals to suppress oscillations in the DC bus voltage, thereby stabilizing the system without changing the basic DC power supply structure
Solution Approach 2:
The damping control system dynamically adjusts control parameters (such as damping coefficients and control gains) based on the detected oscillation characteristics of the DC bus voltage. By changing these parameters in response to varying operating conditions, the system maintains voltage stability across different load and frequency conditions
2Productivity
If faster switching speeds are used in PWM systems, then productivity is improved, but noise radiation from long cables increases
Solution Approach 1:
The damping control system acts as an intermediary that allows high switching speeds to be maintained while suppressing the propagation of noise along the cables. The control system filters out the harmful high-frequency components that cause noise radiation while preserving the benefits of fast switching for motor control performance
3Adaptability or versatility
If multiple motor controllers are remotely located with long cables, then system versatility is improved, but oscillating voltage occurs due to interference between LC circuit and inverter circuit
Solution Approach 1:
The damping control system is distributed across multiple motor controllers, with each controller equipped with its own damping control unit. This allows the system to maintain versatility in configuration while each local control unit independently suppresses oscillations, preventing the propagation of voltage instabilities through the DC bus network
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 servo DC feeder system effectively reduces oscillating voltages across the power feeding path by maintaining the gain of the power supply below the motor controller's gain at relevant frequencies, ensuring system stability.
Implementation Method 1
a current control loop including a notch filter having a center frequency corresponding to a frequency to occur from an oscillating voltage across the power feeding path
Data Source
AI summary
A servo direct-current feeder system can reduce an oscillating voltage across a power feeding path. The servo direct-current feeder system includes a direct-current power supply, a plurality of motor controllers that each control a servomotor, and a power feeding path that distributes power from the direct-current power supply to the plurality of motor controllers. Each of the plurality of motor controllers includes a current control loop unit that controls a current flowing through the servomotor. The current loop unit includes a current control loop including a notch filter having a center frequency corresponding to a frequency to occur from an oscillating voltage across the power feeding path.