Multi-Discipline | PartQuest™ Explore

Member of the PartQuest Explore Development Team. Focused on modeling and simulation of analog, mixed-signal and multi-discipline systems covering a broad range of applications, including power electronics, controls and mechatronic systems.

Description

Design example from the Webinar: “The Basics of Circuit and System Simulation with systemvision.com”. View the archive presentation here: http://www.systemvision.com/webinarsThis design represents a simple automotive (12V) coffee cup warmer, with digital thermostat. It is not meant to be a practical design, but rather to show some of the capabilities of modeling multi-discipline electro-thermal systems in systemvision.com.The design includes a "plant" model with both static and dynamic thermal aspects, including a tungsten heater element, conduction and radiation heat transfer, and heat capacitance. A "graphical" model of the temperature sensor includes a "math function-block" to set the gain (sensitivity) and bandwidth. The closed loop performance of the system is shown to be very sensitive to the sensor bandwidth (i.e. try using 0.5Hz vs. 5 Hz for the pole frequency "FP" in LPF1).The thermostat includes voltage-to-digital converter, with a threshold level that specifies the temperature regulation set-point. A digital clock and D flip-flop sample and preserve the desired state of the heater switch during each clock cycle.

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Circuit Breaker - Single Phase AC

Darrell
Designer10

Darrell

Member for

10 years 5 months

624

designs

10

groups

Big fan of VHDL-AMS

Description

This is a physical or “assembly” model of an electro-magnetic circuit breaker. Rather that modeling the pure electrical “behavior” of that type of circuit protection device, this model represents the actual assembly of physical components which could be used to construct a real circuit breaker. The components are multi-discipline, including electrical, magnetic and mechanical natures. The color coding of the connections among them makes it easy to see these various aspects and their interactions. The section with black connections represents the electrical aspect. The voltage source is the AC line-in voltage, and it is applied across a switch and winding element which are part of the circuit breaker. The switch represents the make/break function of the contactors. A fixed 8 Ohm load resistor is attached to this protected part of the circuit, as well as a switched additional 8 Ohm load in parallel.The section with purple connections represents the magnetic aspect of the breaker. The winding current produces an MMF in proportion to the number of turns, and this MMF drives flux around the magnetic loop. The Neodymium-Iron-Boron permanent magnet also drives flux around the loop, but in one direction only. The magnetic core model represents the flux path through the iron, and the air-gap model represents the energy conversion between the magnetic and mechanical domains.The section with orange connections represents the mechanical (translational) aspects, including a hard-stop which limits the travel of the moving armature, a preload spring, plus the viscous drag and mass of the armature. A simple “glue” model was created to convert the armature displacement into a logical control signal that opens the breaker switch to interrupt the load current, when the air-gap exceeds the contactor over-travel length. The user’s ability to easily create a new custom VHDL-AMS model, when the needed function doesn’t already exist, has value which cannot be overstated.The circuit breaker functions when the current in the winding is of the right polarity and magnitude to create an MMF that sufficiently cancels the MMF of the permanent magnet. This causes a flux drop across the air-gap, to the point where the magnetic attraction force can no longer overcome the pre-load return force of the spring. The armature is then rapidly pushed away. In the simulation results, note that the additional load is applied at 60 msec. The current in the winding increases to just over 40A (peak), and the air-gap force drops below 8N, at which time the armature begins to pull away, opening the electrical circuit. The armature bounces as it reaches the stiff travel limit.This model can be used to re-size or select alternate components (e.g. try a spring with different stiffness or a different magnetic material). It can also be used to assess margins on the current trip level (e.g. try a 10 Ohm resistor for the “additional” load, the breaker won’t trip!), or the opening speed or other performance aspects. This type of “assembly” model is also suitable for exploration of new design concepts.

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Coffee Cup Warmer - Digital

Mike Donnelly
Designer19

Mike Donnelly

Member for

Circuit Breaker - Single Phase AC

Darrell
Designer10

Darrell

Member for

Coffee Cup Warmer - Digital

Mike DonnellyDesigner19

Mike Donnelly

Member for

Circuit Breaker - Single Phase AC

DarrellDesigner10

Darrell

Member for

Mike Donnelly
Designer19

Darrell
Designer10