Vehicle Control Device Modulation Voltage Torque
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Solution Overview
Problem
Existing vehicle control systems for electric motors often result in insufficient output torque due to low voltage from converters, which fails to meet driver acceleration requests.
Innovation Solution
A control device that calculates and adjusts the output voltage from a converter to ensure a target degree of modulation for the inverter, prioritizing a minimum voltage necessary for the motor's target torque over a requested voltage, thereby preventing voltage drops that could impair motor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the output voltage from the converter is lowered to maintain the degree of modulation at a target value, then the degree of modulation is maintained, but the output torque from the electric motor becomes insufficient
Solution Approach 1:
The control device dynamically adjusts the degree of modulation parameter based on the relationship between requested voltage and minimum voltage. When minimum voltage exceeds requested voltage, the system changes the modulation degree to ensure sufficient motor torque while managing converter output voltage effectively
Solution Approach 2:
The control device continuously monitors the actual degree of modulation and compares it with the target value, then adjusts the converter output voltage accordingly. The feedback mechanism ensures that when minimum voltage is higher than requested voltage, the system responds by maintaining higher voltage to prevent torque deficiency
2Reliability
If the output voltage from the converter is lowered, then the degree of modulation increases, but the voltage supplied to the electric motor decreases
Solution Approach 1:
The system changes the operating parameters of the converter and inverter based on the calculated minimum voltage requirement. When minimum voltage exceeds requested voltage, the converter output voltage parameter is adjusted to maintain sufficient motor voltage while achieving the target degree of modulation
3Reliability
If the output voltage from the converter is lowered, then the degree of modulation increases, but the maximum torque output by the electric motor decreases
Solution Approach 1:
The control device dynamically changes the degree of modulation parameter based on the comparison between requested voltage and minimum voltage. When minimum voltage is higher, the system adjusts parameters to ensure the motor receives sufficient voltage for maximum torque output while maintaining effective converter operation
Solution Approach 2:
The feedback control mechanism continuously monitors motor torque requirements and adjusts the converter output voltage and inverter degree of modulation accordingly, ensuring that maximum torque capability is maintained when minimum voltage exceeds requested voltage
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 approach ensures the electric motor achieves sufficient torque output, meeting driver acceleration demands by maintaining or increasing the output voltage to the minimum required level for the motor's target torque, thus overcoming the issue of insufficient torque.
Implementation Method 1
a converter (12) converting and outputting a voltage
Implementation Method 2
an inverter (14) converting DC power output from the converter (12) to AC power
Data Source
AI summary
On a vehicle, a converter converting and outputting a voltage, an inverter converting DC power output from the converter to AC power, and a motor driven by AC power supplied from the inverter are mounted. A control device calculates a requested voltage VHreq as an output voltage from a converter for bringing a degree of modulation Kmd of the inverter closer to a prescribed target degree of modulation Kmd#, calculates from target torque of the motor, a minimum voltage VHmin as a minimum value for an output voltage from the converter which can realize target torque of the motor, and controls the converter such that the output voltage VH from the converter is closer to a value which is greater one of the requested voltage VHreq and the minimum voltage VHmin.