PWM | PartQuest™ Explore

The AS123 LED Driver from ACME Semiconductor (fictional) provides fully integrated PWM dimming and a programmable current set-point. This IC is specifically for automotive rear combination (tail/stop) lighting applications. It tightly regulates the desired string current under conditions of widely varying applied DC voltage.

The PWM dimming function, which switches the LED on and off at just over 300 Hz, is active when the line input pin is high and the "PWM_disable" pin is low (

The AS123 supports current programming using a single external resistor (see r_iset in the schematic). The resistor value can be selected to give the desired LED string current, using the following formula:

r_iset = 1.85/i_desired

The AS123 is capable of regulating up to 100mA per string continuously. Therefore the value of r_iset should be no less than 18.5 Ohms. The user can change this resistor value and run a new simulation, to see the effect of this change on the LED string current.

See a "functional block diagram" schematic model of the ACME AS123 here: https://www.systemvision.com/design/acme-as123-led-driver-schematic-model

-------------- End of Example Application Note ------------------

If you are a component supplier, this type of "Live Application Note" can help your potential customers better understand the features and benefits of your components.

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EPS System with PMSM Motor and Toshiba TPHR7904PB Power MOSFET JSAE 2025

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Description

This Electric Power Steering (EPS) System design includes a PWM Switching Inverter circuit that uses Toshiba TPHR7904PB 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, "EPS System with PMSM - Pre-Circuit Design for Toshiba 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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EPS System with 1D PMSM Model and DQ/SVM Drive JSAE 2025

Designer241497

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Description

This Electric Power Steering (EPS) System design includes a MotorSolve generated Permanent Magnet Synchronous Machine (PMSM) model and a PWM Drive circuit. The drive includes a D-Q control algorithm, and uses space-vector modulation (SVM) to generate the digital PWM signals to the switches of the bridge.

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-lag compensator is used to improve system stability.

In a companion version of this design, "EPS System with MotorSolve Generated PMSM Model and Ideal Drive", Clarke and Park Transform models are used with a continuous ideal voltage drive. This shows the ability to develop motor controls and drives at the abstract level and also at the circuit level.

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Copy of Fan System with 3-Phase Induction Motor and Power MOSFET Drive - Nexperia PSMNR90-40 - on Sat, 06/28/2025 - 09:36

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Copy of Fan System with 3-Phase Induction Motor and Power MOSFET Drive - on Wed, 06/18/2025 - 16:38

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Welcome to the community!!

Copy of PMSM Motor and PWM Drive - on Mon, 06/09/2025 - 11:21

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Welcome to the community!!

Description

Permanent Magnet Synchronous Machine (PMSM) and PWM Drive circuit, with mechanical load. The drive includes a D-Q control algorithm, and uses space-vector modulation (SVM) to generate the digital PWM signals to the switches of the bridge.

The waveform plot in the upper left shows the drive command (light blue waveform), with values 0 to 1, where 1 is commanding the maximum quadrature current of 10 A. The motor's response is the output shaft angle in radians (orange waveform), and shows that increasing torque command results in greater rotational displacement against the load spring. The waveform plot in the upper right shows the actual motor torque (green waveform) and the A-phase current (dark blue waveform).

In a companion version of this design, "PMSM Motor And Ideal Drive", Clarke and Park Transform models are used with a continuous ideal voltage drive.This shows the ability to develop motor control and drives at the abstract level and at the circuit level.

In yet another version of this design example, the ideal switches will be replaced with actual power MOSFET device models. This can help in bridge component sizing and performance specification.

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