Electromotor Current Loop Feedback Control for Dynamic Response

Solution Overview

Problem

Existing electromotor control methods for electric vehicles respond slowly due to reliance on velocity loop feedback control, which limits dynamic responsiveness.

Innovation Solution

Implementing a current loop feedback control method that sets target alternating and direct axis currents based on rotor angular velocity and torque, performing Park and Clark conversions, and using PI regulation to output required currents and voltages for faster PWM control waveform calculation and motor drive.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If velocity loop feedback control is used, then the control structure is simple, but the dynamic responding is slow

Engineering Contradiction:

Improvedynamic responding speedVSAvoidcontrol loop complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The patent implements a current loop feedback control system that directly feeds back the actual current to the controller. This closed-loop feedback mechanism enables real-time monitoring and adjustment of current, achieving fast dynamic response without requiring complex velocity loop structures. The feedback signal is processed through a current regulator that automatically adjusts the PWM duty cycle to maintain the desired current level.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces the traditional velocity-based control mechanism with a direct current-based control mechanism. By substituting the velocity loop with a current loop, the system achieves faster response characteristics inherent to current control while eliminating the complexity of velocity sensing and processing. The current regulator directly controls the motor current without intermediate velocity conversion steps.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Speed

If current loop feedback control is implemented, then the dynamic responding is fast, but the control calculation complexity increases

Engineering Contradiction:

Improvedynamic responding speedVSAvoidcontrol calculation complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The patent transforms the control parameters from velocity-based to current-based throughout the control system. By changing the fundamental control parameter to current, the system simplifies the control calculations required for fast response. The current regulator uses standard PI control algorithms operating on current signals, avoiding complex transformations that would arise from velocity-based control while maintaining fast dynamic characteristics.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If velocity loop control is used, then the system is easier to implement, but control accuracy and stability are reduced

Engineering Contradiction:

Improvecontrol accuracyVSAvoidimplementation ease

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent implements a current loop feedback control system that directly feeds back the actual current to the controller. This closed-loop feedback mechanism enables real-time monitoring and adjustment of current, achieving fast dynamic response without requiring complex velocity loop structures. The feedback signal is processed through a current regulator that automatically adjusts the PWM duty cycle to maintain the desired current level.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces the traditional velocity-based control mechanism with a direct current-based control mechanism. By substituting the velocity loop with a current loop, the system achieves faster response characteristics inherent to current control while eliminating the complexity of velocity sensing and processing. The current regulator directly controls the motor current without intermediate velocity conversion steps.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS8207701B2Control method of electromotor

Publication Date: 2012.06.26 BYD CO LTD

AI summary

A control method of the electromotor comprises: setting a target alternating axis current based on the rotor angular velocity of the electromotor and a target direct axis current based on the torque of the motor; simultaneously detecting three-phase currents and current rotor position angle of the electromotor; converting the three-phase currents to an actual alternating axis current and an actual direct axis current by Park and Clark conversions; inputting the difference between the target current and the actual current to a current loop, outputting the required direct axis current and the required alternating axis current; determining the three phase voltages according to the required direct axis current and alternating axis current and the angle of the electromotor rotor position; obtaining PWM control waveform through three-phase voltages, wherein said PWM control waveform is configured to control the conversion from direct current to alternating current and drives the electromotor.