Boost Converter Control via Dynamic Power Limiting
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Solution Overview
Problem
In motor control systems, particularly in electric vehicles, the boost converter's performance is compromised due to temperature increases and voltage oscillations at the inverter side, leading to instability from overvoltage or overcurrent issues, which existing methods fail to adequately address.
Innovation Solution
A control method that determines a limiting power based on the motor generator's operating point to suppress voltage oscillations by controlling the operating point of the motor generator, ensuring the passing power of the boost converter does not exceed this limiting power, thereby stabilizing the inverter side voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the passing power of the boost converter is limited to suppress temperature increase, then the temperature of the boost converter is reduced, but the motor system becomes unstable due to overvoltage or overcurrent caused by oscillation of the output voltage
Solution Approach 1:
The patent applies dynamics by making the limiting power value variable rather than fixed. The controller dynamically adjusts the limiting power based on the operating point of the motor generator, allowing the system to adapt to different operating conditions. This resolves the contradiction by enabling temperature suppression when needed while maintaining system stability when operating conditions change, preventing both overheating and voltage oscillation instability.
Solution Approach 2:
The patent changes the parameter of limiting power from a constant value to a variable value that depends on the motor generator's operating point. By adjusting this parameter based on real-time operating conditions, the system can suppress temperature increase at certain operating points while preventing voltage oscillation and maintaining stability at other operating points, thus resolving the technical contradiction.
2Temperature
If the passing power is limited by considering only the temperature increase, then the temperature of the boost converter is controlled, but the oscillation of the terminal voltage at the inverter side is not suppressed
Solution Approach 1:
The patent changes the limiting power parameter from a temperature-based fixed limit to an operating-point-based variable limit. This allows the system to consider both temperature constraints and voltage stability requirements by adjusting the limiting power according to the motor generator's operating conditions, thereby suppressing both temperature increase and terminal voltage oscillation simultaneously.
Solution Approach 2:
The patent implements feedback by continuously monitoring the operating point of the motor generator and adjusting the limiting power accordingly. This closed-loop control ensures that the limiting power is optimized for both temperature suppression and voltage stability, resolving the contradiction by using real-time operating information to dynamically adjust the power limit.
3Temperature
If a fixed limiting power is applied to the boost converter, then the temperature increase is suppressed, but the system cannot adapt to different operating points of the motor generator
Solution Approach 1:
The patent applies dynamics by transforming the fixed limiting power into a dynamic, adaptive parameter that changes with the motor generator's operating point. This allows the system to maintain temperature suppression across different operating conditions while adapting to the specific requirements of each operating point, thereby resolving the contradiction between temperature control and adaptability.
Solution Approach 2:
The patent makes the limiting power control universal by designing it to work across multiple operating points of the motor generator. The operating-point-based limiting power approach allows the same control mechanism to effectively suppress temperature increase whether the motor is operating at low speed, high speed, high torque, or low torque conditions, providing both temperature control and broad adaptability.
Data Source
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Figure 3(a)~3(b)
AI summary
A control method for a motor system, the motor system having a battery; a boost converter configured to increase DC voltage supplied by the battery; an inverter connected to the boost converter and configured to execute a conversion between DC power and AC power; and a motor generator connected to the inverter. The control method comprising: a limiting power determination step of determining a limiting power in response to an operating point of the motor generator such that an oscillation of a terminal voltage of the boost converter at a side of the inverter is suppressed; and a controlling step of controlling the operating point of the motor generator such that a passing power of the boost converter does not exceed the limiting power.