Current Source Inverter Control via D-q Axis Current Offsets
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Solution Overview
Problem
Current motor control systems for vehicles, particularly in hybrid and electric vehicles, face challenges in efficiently managing torque and current distribution across electric motors, leading to suboptimal performance and energy efficiency.
Innovation Solution
A motor control system comprising a d-q target module, offset module, adder module, and driver module, which determine and adjust target currents for a current source inverter (CSI) to apply power to electric motors based on torque requests, capacitor currents, and motor speed, ensuring precise control of d-axis and q-axis currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional motor control systems are used to manage torque and current distribution, then the system structure is simple, but torque management efficiency and energy efficiency deteriorate
Solution Approach 1:
The control system segments current control into two independent components: d-axis current control for flux management and q-axis current control for torque production. This segmentation allows precise independent optimization of each current component, improving torque management efficiency while maintaining manageable system complexity through modular control architecture.
Solution Approach 2:
The system dynamically adjusts d-axis and q-axis current targets based on real-time operating conditions including motor speed, load torque, and capacitor voltage. The controller continuously modifies current references and switching strategies to optimize performance across varying operating points, enabling adaptive torque management that improves overall efficiency.
2Measurement precision
If conventional current control methods are used, then the control algorithm is simple, but current regulation precision deteriorates
Solution Approach 1:
The control system implements closed-loop feedback by continuously monitoring actual d-axis and q-axis currents, comparing them with target values, and adjusting PWM switching duty cycles to minimize errors. This feedback mechanism ensures precise current regulation while the modular structure keeps the control algorithm systematically manageable.
Solution Approach 2:
The system dynamically changes control parameters including current references, PWM duty cycles, and switching frequencies based on operating conditions. By adjusting these parameters in real-time, the system achieves high current regulation precision across different motor speeds and load conditions without requiring overly complex control logic.
3Use of energy by moving object
If basic inverter control is used, then the system structure is simple, but energy efficiency deteriorates
Solution Approach 1:
The inverter control system dynamically optimizes energy efficiency by adjusting switching patterns, PWM duty cycles, and current references based on real-time motor operating conditions. The controller implements loss minimization strategies including dead-time compensation and optimal switching sequences, achieving high energy efficiency while maintaining a structured modular control architecture.
Solution Approach 2:
The control system automatically adapts its operation to minimize energy losses without external intervention. It continuously monitors motor parameters and operating conditions, then self-adjusts current references and switching strategies to optimize efficiency across the entire operating range, reducing the need for complex external control mechanisms.
Data Source
AI summary
A motor control system includes: a d-q target module configured to, based on a target torque of an electric motor, determine a first target d-axis current and a first target q-axis current; an offset module configured to, based on a capacitor current through capacitors connected across phases of the electric motor, determine a d-axis current offset and a q-axis current offset; an adder module configured to determine a second target d-axis current based on a sum of the first target d-axis current and the d-axis current offset and to determine a second target q-axis current based on a sum of the first target q-axis current and the q-axis current offset; and a driver module configured to, based on the second target d-axis current and the second target q-axis current, switch switches of a current source inverter (CSI) module configured to apply power to the phases of the electric motor.