Dual Motor Control Device Torque Distribution
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Solution Overview
Problem
In electrically driven vehicles with two control devices for motor control, existing configurations either increase calculation volume in one device or communication volume between devices, leading to an imbalance and inefficiency, especially in vehicles with in-wheel motors.
Innovation Solution
The configuration involves the first control device calculating the target torque and current command, then sending it to the second control device, which performs feedback control using the current command, phase current, and rotational angle, reducing the need for the second device to calculate the current command and eliminating the need for feedback value communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the second control device calculates the current command and performs feedback control, then the motor control precision is improved, but the calculation volume of the second control device increases
Solution Approach 1:
The control functions are segmented between two control devices: the first control device calculates the torque command based on accelerator position and vehicle state, while the second control device calculates the current command based on the torque command and performs feedback control. This segmentation distributes the calculation workload and allows each device to specialize in specific control tasks.
2Measurement precision
If the second control device performs pulse generation and switching control, then the motor control precision is improved, but the communication volume between control devices increases
Solution Approach 1:
The feedback control function is extracted from the first control device and assigned to the second control device. The second control device receives the torque command from the first device, then independently performs current command calculation, pulse generation, and switching control using feedback from phase current and motor angle sensors. This extraction reduces the communication burden on the first control device.
3Measurement precision
If three signal lines are provided for sine, cosine and excitation signals in the resolver, then the rotational angle detection precision is improved, but the communication volume between control devices increases
Solution Approach 1:
The resolver serves as an intermediary device that detects the motor's rotational angle and provides this information to the second control device. The second control device uses the rotational angle information along with phase current feedback to perform precise feedback control and generate switching signals, thereby maintaining high control precision while managing communication volume efficiently.
Data Source
AI summary
There is provided an electrically driven vehicle that well balances calculation volumes and communication volumes of two control devices configured to drive and control motors for driving. The electrically driven vehicle comprises at least one motor for driving and a first control device and a second control device configured to control the motor. The first control device is configured to calculate a target torque that is to be output from the motor, based on information including an accelerator position, to calculate a current command based on the calculated target torque, and to send the calculated current command to the second control device. The second control device is configured to use the current command, a phase current of the motor and a rotational angle of the motor such as to drive the motor by feedback control.