EV Motor Controller Inverter Boosting for Low-Voltage Torque
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Solution Overview
Problem
Electric vehicles face insufficient endurance capability and low energy utilization efficiency due to insufficient torque output from the drive motor when the battery output voltage is low, and the use of bidirectional DC-DC conversion circuits increases costs and volume while causing heat generation issues.
Innovation Solution
A motor controller with an inverter circuit and control circuit that adjusts the voltage at both ends of the bus capacitor by controlling switching transistors in the inverter circuit, forming either a boost or buck circuit to maintain optimal voltage levels and improve torque output and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a bidirectional DC-DC conversion circuit is used to increase bus voltage, then torque output capability and working efficiency are improved, but costs and system volume increase
Solution Approach 1:
The patent combines the voltage boosting function with the existing inverter circuit by utilizing the motor winding as an inductor and the bus capacitor as a resonant capacitor, eliminating the need for a separate DC-DC conversion circuit. The inverter circuit performs both motor control and voltage boosting functions simultaneously.
Solution Approach 2:
The inverter circuit is designed to perform multiple functions: motor control and voltage boosting. By using the motor winding and bus capacitor in a resonant circuit configuration, the same circuit components serve dual purposes, reducing overall system complexity and volume.
2Power
If a bidirectional DC-DC conversion circuit is used to increase bus voltage, then torque output capability is enhanced, but heat generation increases
Solution Approach 1:
The patent employs periodic switching of the inverter circuit to create a resonant oscillation between the motor winding inductor and bus capacitor. This periodic action enables voltage boosting through resonance rather than continuous power conversion, reducing heat generation.
Solution Approach 2:
The system changes the operating parameters of the inverter circuit, specifically utilizing resonant frequency operation and adjusting switching duty cycles to achieve voltage boosting. This parameter change enables efficient energy transfer with minimal losses and reduced heat generation.
3Use of energy by moving object
If the power battery output voltage is low, then energy utilization efficiency decreases, but adding voltage boosting increases system complexity
Solution Approach 1:
The system uses its own existing components (motor winding and bus capacitor) to perform voltage boosting without requiring external or additional dedicated components. The motor winding serves as both the actuator and the inductor for voltage boosting, making the system self-sufficient.
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
The solution enhances the torque output and efficiency of the drive motor, improves the endurance capability of the electric vehicle, and reduces costs and heat generation by eliminating the need for a bidirectional DC-DC conversion circuit.
Implementation Method 1
the inverter circuit includes a plurality of switching transistor bridge arms... control the inverter circuit to increase a voltage at both ends of the bus capacitor
Data Source
AI summary
This application provides a motor controller for an electric vehicle. The motor controller includes a control circuit and an inverter circuit. The control circuit is configured to: in response to that the drive motor rotates with a pair of wheels of the electric vehicle, control a switch module to connect a center tap of the multiphase winding to the other end of the power battery, and control the inverter circuit to adjust a voltage at both ends of the bus capacitor. The bridge arms of the inverter circuit of the motor controller provided in this application and the winding of the drive motor form a voltage conversion circuit to adjust the voltage at both ends of the bus capacitor, to improve power performance and vehicle endurance of the electric vehicle.