PN-Busbar Regenerative Control via Load Ratio Comparison
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Solution Overview
Problem
Existing PN-busbar common systems face challenges with oversized system configurations and high costs due to the need for network management firmware and advanced motor drive devices with master controllers for regenerative control, as well as complex wiring and costly network management in multiaxial motor control devices.
Innovation Solution
A PN-busbar common system where each motor drive device individually controls regenerative power based on regenerative-control start and stop voltages, calculates a regenerative load ratio, and enables or disables regenerative control based on comparisons with set load ratios, eliminating the need for network management firmware and advanced motor drive devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a master controller or master function is added to manage regenerative capability, then regenerative control can be executed efficiently, but the system configuration becomes oversized and more advanced motor drive devices are needed
Solution Approach 1:
The patent divides the regenerative control function into independent segments that can be distributed across multiple motor drive devices. Each device autonomously determines whether to execute regenerative control based on local conditions (motor regenerative power, bus voltage, etc.), eliminating the need for a centralized master controller while maintaining overall system efficiency.
Solution Approach 2:
Each motor drive device is equipped with the capability to autonomously make decisions about regenerative control execution without requiring external management from a master controller. The device self-evaluates its regenerative power availability and bus voltage conditions, then independently determines whether to activate regenerative control, reducing system complexity.
2Productivity
If network wiring is added to connect motor drive devices for regenerative control, then regenerative control can be executed in each device, but the wiring becomes more complicated and costs increase
Solution Approach 1:
The patent extracts the network communication requirement from the regenerative control system. By allowing each motor drive device to independently monitor bus voltage and assess its own regenerative power capability, the system eliminates the need for inter-device network wiring while still achieving coordinated regenerative control through shared bus electrical characteristics.
Solution Approach 2:
The DC bus serves as an electrical intermediary that enables communication between motor drive devices without requiring explicit network wiring. Changes in bus voltage caused by regenerative operations naturally propagate information across all connected devices, allowing them to coordinate regenerative control through the shared electrical medium rather than dedicated communication channels.
3Reliability
If only one motor drive device with maximum regenerative power is operated for regenerative control, then regenerative function faults are prevented, but the amount of power that can be regenerated is limited
Solution Approach 1:
The patent implements dynamic regenerative control where multiple motor drive devices can simultaneously execute regenerative control based on real-time conditions. Each device continuously monitors bus voltage and its own motor's regenerative power availability, dynamically adjusting its contribution to overall regenerative power without risking function faults through coordinated voltage-based control.
Solution Approach 2:
The system changes the control parameter from relying on a single device's maximum regenerative power to utilizing multiple devices' combined regenerative power, modulated by bus voltage thresholds. This parameter change allows the system to scale regenerative power capacity across multiple devices while maintaining stability through voltage-based coordination.
Data Source
AI summary
A PN-busbar common system includes motor drive devices for a plurality of motors, each of which is supplied with power from a common PN-busbar, where the motor drive devices individually drive the corresponding motors. Each of the motor drive devices executes a regenerative control on a basis of a regenerative-control start voltage, and controls to stop the regenerative control on a basis of a regenerative-control stop voltage, and also individually calculates a regenerative load ratio to control to enable or disable the regenerative control on a basis of a result of a comparison between a calculated regenerative load ratio and a set regeneration-capable load ratio.