Regenerative PTO Control Circuit Using PLL Phase Synchronization
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Solution Overview
Problem
Existing systems for dynamic electric regenerative power take-off from vehicle traction shafts require synchronism between the generator and converter, necessitating costly and complex sensors to detect the generator's phase angle and speed, and are not effectively engaged during vehicle startup or braking, due to safety concerns with braking systems.
Innovation Solution
An electronic control circuit with instant voltage and current sensors, a direct-quadrature transform calculator, and a phase-locked loop (PLL) synchronizes the generator phase angle with the converter state without the need for encoder sensors, enabling seamless transition between traction and regenerative modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sensors are used to detect the generator's phase angle and speed, then the synchronism between generator and converter is maintained, but the system cost and complexity increase
Solution Approach 1:
The patent replaces mechanical sensors (encoders, magnetic sensors) with an electrical signal-based detection method. The initial phase angle is detected by analyzing the electrical signals from the generator windings through mathematical transformations (Park transformation, Clarke transformation), eliminating the need for physical sensors on the generator shaft.
Solution Approach 2:
The patent introduces an intermediary detection method using the electrical converter's own switching signals and the generator's back-EMF signals. By correlating the converter state with the generator voltage signals through mathematical processing, the system indirectly determines phase angle and speed without direct mechanical sensing.
2Reliability
If sensors are used to detect the generator's phase angle and speed, then the synchronism between generator and converter is maintained, but the maintenance requirements and cost increase
Solution Approach 1:
The patent replaces mechanical sensors (encoders, magnetic sensors) with an electrical signal-based detection method. The initial phase angle is detected by analyzing the electrical signals from the generator windings through mathematical transformations (Park transformation, Clarke transformation), eliminating the need for physical sensors on the generator shaft.
Solution Approach 2:
The system uses its own existing electrical components (generator windings, converter switching circuits) to detect phase angle and speed. The generator's back-EMF signals and the converter's switching states serve as self-diagnostic indicators, eliminating the need for external sensing hardware.
3Productivity
If the regenerative system is engaged during braking, then energy recovery is maximized, but safety issues arise with braking systems
Solution Approach 1:
The patent implements periodic engagement and disengagement of the regenerative system based on operating conditions. During braking, the system is disengaged to prioritize safety; during normal operation, it is engaged for energy recovery. This periodic switching optimizes both safety and productivity.
Solution Approach 2:
The system dynamically adjusts its engagement state based on real-time operating conditions. The controller monitors vehicle speed, brake status, and power demand to determine when to engage or disengage regenerative braking, transitioning smoothly between traction and regenerative modes.
4Reliability
If the regenerative system is engaged only after minimum speed is reached, then braking system safety is maintained, but energy recovery opportunities are lost
Solution Approach 1:
The system dynamically adjusts its engagement state based on real-time operating conditions. The controller monitors vehicle speed, brake status, and power demand to determine when to engage or disengage regenerative braking, transitioning smoothly between traction and regenerative modes.
Solution Approach 2:
The patent implements periodic engagement and disengagement of the regenerative system based on operating conditions. During braking, the system is disengaged to prioritize safety; during normal operation, it is engaged for energy recovery. This periodic switching optimizes both safety and productivity.
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 solution eliminates the need for encoder sensors, reduces system complexity and cost, and allows for efficient engagement and disengagement of the regenerative system during vehicle operation, including startup and braking, while ensuring safe operation with braking systems.
Implementation Method 1
a synchronous electrical generator for coupling the vehicle traction shaft
Implementation Method 2
a phase-locked loop (PLL) synchronizes the generator phase angle with the converter state
Data Source
AI summary
A control circuit for electric regenerative power take-off includes: instant voltage and current sensors for connecting to power connection of a synchronous generator for capturing a triphasic voltage and a triphasic current, respectively; voltage-based and current-based direct-quadrature (“DQ”) transform calculators outputting an equivalent two phase DQ tensor of a three vector triphasic voltage of the captured voltage and an equivalent two phase DQ tensor of a three vector triphasic current of the captured current, respectively; a current-based DQ controller outputting “desired” active-power and reactive-power voltages for the power controller; a phase-locked loop (“PLL”) for defining the operation angle of the power converter; processor switching between 1st and 2nd operation stages in order to engage or disengage the power converter from the synchronous generator, and to synchronize the PLL with the captured voltage using “Q output” from either the voltage-based DQ transform calculator or the current-based DQ controller.