Motor Control Unit Interleaved PWM for EV Charging Ripple Control
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Solution Overview
Problem
Existing electric vehicle charging systems face challenges in charging vehicles with high voltage batteries (600 V to 800 V) due to limited output voltage ranges of charging piles (220 V to 500 V), and there is a need to control bridge arms to manage heat and current ripple effectively.
Innovation Solution
A powertrain system with a motor control unit and three bridge arms, where PWM signals are interleaved to control the bridge arms, ensuring safe heat management and reducing current ripple by staggered turning on and off of the bridge arms, thereby balancing heat generation and current ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the bridge arm is turned on or off to adapt to charging piles with output voltage ranging from 220 V to 500 V, then the voltage output by the charging pile can be increased to match the 600 V to 800 V power battery, but the heat generated by magnetic steel in the motor increases and current ripple increases
Solution Approach 1:
The patent applies periodic action through interleaved PWM signals with different phases. The first PWM signal controls the first bridge arm while the second PWM signal controls the second bridge arm, with their rising and falling edges staggered by preset time periods. This periodic, phased switching approach distributes the magnetic steel excitation over time, allowing heat dissipation between cycles and preventing excessive temperature rise while maintaining the required voltage output capability.
2Power
If the bridge arm is turned on or off to adapt to charging piles with output voltage ranging from 220 V to 500 V, then the voltage output by the charging pile can be increased to match the 600 V to 800 V power battery, but the ripple of output current increases
Solution Approach 1:
The interleaved PWM control strategy employs periodic switching with phase shifts between bridge arms. By staggering the turn-on and turn-off times of different bridge arms through preset time periods, the current ripple generated by each switching event is distributed and partially canceled out, reducing the overall current ripple while maintaining the voltage boosting function.
Solution Approach 2:
The patent segments the single PWM control into multiple interleaved PWM signals controlling different bridge arms. Instead of switching one bridge arm at a time with large current ripple, the control is divided into multiple phases with smaller, staggered switching events, which reduces the peak current ripple while achieving the same voltage multiplication effect.
3Device complexity
If traditional PWM control is used without interleaving, then the control is simple, but the heat generated by magnetic steel exceeds safe range and current ripple is large
Solution Approach 1:
The interleaved PWM control generates periodic switching patterns with phase shifts between bridge arms. This periodic action distributes magnetic steel excitation over time, allowing heat dissipation between cycles, thereby controlling temperature within safe ranges while maintaining relatively simple control logic through standardized signal generation.
Data Source
AI summary
A powertrain, a charging control method, and an electric vehicle. The powertrain includes a motor control unit and a motor. The motor control unit includes three bridge arms and a controller. A first end of a direct current power supply is coupled to one end of each bridge arm and a first end of the power battery. A second end of the power battery is coupled to the other end of each bridge arm. A midpoint of each bridge arm is coupled to one end of a motor winding. The other end of each motor winding is coupled to a second end of the direct current power supply. Two bridge arms of each bridge arm are turned on or off based on a first PWM signal and a second PWM signal. The first PWM signal and the second PWM signal are interleaved.