Motor Control Circuit for EV Battery Charging Without Boost Converter
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Solution Overview
Problem
The existing power battery charging methods for electric vehicles require an additional boost circuit for boost charging, increasing the volume and cost of the apparatus.
Innovation Solution
A motor control circuit comprising a first switch module, a three-phase inverter, and a control module forms a current loop with a three-phase alternating current motor, allowing for adaptive charging by boosting or direct charging based on the voltage of the power supply module and power battery, eliminating the need for an external boost circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If boost charging is implemented by adding a DC/DC bridge circuit, then charging capability under voltage mismatch conditions is improved, but device volume and manufacturing cost increase
Solution Approach 1:
The three-phase inverter is designed to perform multiple functions: it serves as both the motor drive inverter and the boost charging inverter. By controlling the inverter to operate in different modes (motor driving mode vs. boost charging mode), the system achieves universal functionality without requiring separate dedicated circuits for each function, thereby resolving the contradiction between adaptability and device complexity
Solution Approach 2:
The patent merges the boost charging circuit functionality into the existing three-phase inverter structure. The inverter's switching devices and LC filter components are utilized for both motor control and voltage boosting operations, combining what would traditionally be separate systems into one integrated unit, thus avoiding additional volume and cost while maintaining charging capability under voltage mismatch conditions
2Device complexity
If direct charging is used without voltage matching, then device complexity is reduced, but charging adaptability deteriorates when power supply voltage is lower than battery voltage
Solution Approach 1:
The system implements dynamic operation modes that can switch between direct charging and boost charging based on real-time voltage conditions. The control module dynamically adjusts the inverter's operating state: when power supply voltage matches battery voltage, direct charging is used for simplicity; when voltage mismatch occurs, boost charging is activated automatically, thus achieving both structural simplicity and charging adaptability
Solution Approach 2:
The patent changes the operating parameters of the inverter based on voltage conditions. By detecting the relationship between power supply voltage and battery voltage, the system adjusts the inverter's switching duty cycle and operating frequency to achieve either direct power transfer or voltage boosting, enabling the system to adapt to different voltage conditions without requiring complex hardware changes
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
This solution enables robust compatibility and adaptability in charging electric vehicle batteries regardless of the power supply voltage, reducing costs by eliminating the need for an extra external boost circuit and ensuring efficient charging.
Implementation Method 1
a boost circuit including a DC/DC bridge circuit, an inductor, and a corresponding control detection circuit further separately need to be added
Implementation Method 2
a three-phase inverter, and a control module, where a power supply module, the first switch module, the three-phase inverter, and a three-phase alternating current motor form a current loop
Data Source
AI summary
A motor control circuit includes a first switch module, a three-phase inverter, and a control module, where a power supply module, the first switch module, the three-phase inverter, and a three-phase alternating current motor form a current loop, the three-phase alternating current motor inputs or outputs a current by using a wire N extending from a connection point of three phase coils, and the control module controls the three-phase inverter, so that the motor control circuit receives a voltage of the power supply module and outputs a direct current. A wire N extends from the three-phase alternating current motor, and further forms different charging loops with the three-phase inverter, the three-phase alternating current motor, and the power battery.