Recirculation Braking for Rapid PMSM and BLDC Deceleration
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Solution Overview
Problem
Conventional braking techniques are inadequate for achieving rapid and controlled deceleration of motors to a non-zero speed, failing to provide a smooth transition to a lower rotational speed effectively.
Innovation Solution
A motor control system employing a multi-state deceleration sequence, including a braking state, bottom-side and top-side recirculation states, and a regeneration state, to manage motor winding current polarity and recirculation within inverter switches, ensuring controlled deceleration through a series of 2-phase or 4-phase voltage vectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional braking techniques are used, then the motor can be decelerated, but the deceleration is not rapid enough and cannot achieve controlled deceleration to non-zero speed
Solution Approach 1:
The braking process is divided into multiple distinct states (first braking state, second braking state, recirculation state) that are executed in sequence. Each state performs a specific function: the first braking state generates braking torque, the second braking state maintains current flow, and the recirculation state manages energy dissipation. This segmentation allows for rapid and controlled deceleration to non-zero speeds by transitioning through optimized control phases.
2Speed
If rapid deceleration is implemented, then deceleration speed improves, but current limits may be exceeded and DC supply bus voltage may fluctuate
Solution Approach 1:
The control system dynamically transitions between different braking states based on real-time motor conditions. The first braking state operates with higher current to achieve rapid deceleration, while the second braking state and recirculation state adjust current levels to maintain safe operating limits. This dynamic state management enables rapid deceleration while preventing current limits from being exceeded and minimizing DC bus voltage fluctuations.
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
Enables rapid and controlled deceleration of motors by managing motor winding current to achieve a desired lower speed without regenerative energy pump-back, maintaining safe current limits and minimizing DC supply bus voltage fluctuations.
Implementation Method 1
These permanent magnet BLDC motors operate by sequentially energizing the stator windings to attract or repel the permanent magnet rotor into rotational motion
Implementation Method 2
Sensor-less BLDC motors often rely on back electromotive force (BEMF) detection to determine the angular position of the permanent magnet rotor
Implementation Method 3
A motor control system employing a multi-state deceleration sequence, including a braking state, bottom-side and top-side recirculation states, and a regeneration state, to manage motor winding current polarity and recirculation within inverter switches
Data Source
AI summary
A motor control system operable to control a motor includes a motor control circuit and an inverter circuit connected to the motor control circuit and configured to connect to the motor at phase output terminals. The inverter circuit, in response to one or more output control signals indicating a deceleration instruction from the motor control circuit, implements a multi-state deceleration sequence for at least one commutation state of a commutation scheme of the motor.