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EPS System with PMSM Motor and Nexperia BUK9Y29-40E Power MOSFET

Designer19

Description

This Electric Power Steering (EPS) System design includes a PWM Switching Inverter circuit that uses Nexperia BUK9Y29-40E Power MOSFETs. The drive includes a D-Q control algorithm, and uses space-vector modulation (SVM) to generate digital PWM signals. These control the ON/OFF state of the switches.

The mechanical load model includes static and kinetic friction, a steering force that varies with rack displacement, as well as various mass, inertia, damping and spring/stiffness elements of the steering system. The steering torque, applied by the vehicle's driver, is assisted by torque from the motor scaled by the gear ratio. For the control, the first gain/pole-zero block (far left) specifies the amount of "torque_assist" gain (assist torque as a multiple of the vehicle operator's torque applied to the steering wheel), as well as providing compensation to improve system stability.

This design focuses on the performance of the switches in the inverter circuit, including tracking of the thermal characteristics of one representative switch. In a companion version of this design, "Electric Power Steering System with Ideal PMSM and Drive", Clarke and Park Transform models are used with a continuous ideal voltage drive, and provides much faster simulation results with a focus on overall system dynamic performance.

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Copy of Electric Power Steering System with Ideal PMSM and Drive - on Sun, 01/31/2021 - 18:07

Designer236852

Description

This design includes an ideal Permanent Magnet Synchronous Machine (PMSM) model, as well as a continuous D-Q controller and drive circuit. The mechanical load model includes static and kinetic friction, a steering force that varies with rack displacement, as well as various mass, inertia, damping and spring/stiffness elements of the steering system. The steering torque, applied by the vehicle's driver, is assisted by torque from the motor scaled by the gear ratio. For the control, a non-linear gain profile is specified in the "torque_assist_table" function, and a lead compensator is used to improve system stability.

Note that this is a "tunable" design. Many of these system parameters can be changed by the user. Then a new simulation can be run and the updated results can be observed in the waveform viewers.

In a companion versions of this design, "EPS System with MotorSolve Generated PMSM Model and Ideal Drive", the ideal PMSM is replaced with a more realistic motor model generated by MotorSolve, the motor design tool. That model includes cogging torque, saturation and torque ripple behavior, which is seen to have a significant effect in this power steering application.

A second companion design, "EPS System with MotorSolve Generated PMSM Model and DQ/SVM Drive", uses both the MotorSolve motor model and also a sampled-data D-Q control algorithm and space-vector modulation (SVM) to control the switches in a power electronics circuit. This shows the ability to develop motor control and drives at the abstract level and also at the circuit level.

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EPS System with PMSM Motor and Nexperia BUK9Y29-40E Power MOSFET

Designer19

Copy of Electric Power Steering System with Ideal PMSM and Drive - on Sun, 01/31/2021 - 18:07

Designer236852

BLDC v3 - on - part2

Designer236011

BLDC v3 - inf - part2

Designer236011

BLDC v3 - on

Designer236011

BLDC v3 - inf

Designer236011

BLDC v3 - buk

Designer236011

BLDC v2 - buk

Designer236011

BLDC v2 - inf

Designer236011

BLDC v2 - on

Designer236011

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