Looking for Analog to PWM signal -

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Discussion Overview

The discussion centers around finding a product that converts standard analog signals (0-10V and/or 4-20mA) into PWM signals with a fixed but adjustable frequency, specifically for a power electronics application. Participants explore potential solutions, including circuit designs and existing products, while emphasizing the need for qualified components due to the critical nature of the application.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests using a 555 timer and a comparator to create a PWM signal from an analog input, describing the configuration needed for this circuit.
  • Another participant highlights the complexity and cost of developing a custom PCB for this application, indicating that qualified products are necessary due to the high stakes involved in controlling a 100KW DC power supply.
  • A circuit diagram is provided by one participant to illustrate the proposed solution using the 555 timer, although it is noted that the output end can be ignored for the purpose of the discussion.
  • Concerns are raised about the appropriateness of seeking solutions in the forum, given the critical nature of the application and the need for fully qualified products.
  • One participant mentions specific products from Axiomatic as potential solutions for the PWM conversion needs.
  • Another participant expresses gratitude for the product suggestion and clarifies that they are looking for existing products rather than circuit design advice.

Areas of Agreement / Disagreement

Participants appear to agree on the necessity of using qualified products for the application, but there is no consensus on the best approach to achieve the desired PWM signal conversion. Multiple viewpoints on potential solutions and product recommendations are present.

Contextual Notes

The discussion reflects the limitations of relying on DIY solutions in high-stakes applications, emphasizing the need for robust, qualified products. The complexity of the circuit design and the associated costs are also noted.

Who May Find This Useful

This discussion may be useful for engineers or technicians involved in power electronics, particularly those seeking reliable methods for converting analog signals to PWM in critical applications.

Windadct
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Hello All:

This may be a repeat post - I looked at my history and did not see it.

I am looking for a product ( finished/qualified) that takes a standard Analog signal ( 0-10V and/or 4-20mA) and converts to a PWM signal with fixed but settable; Frequency of ~ 100 to 5000hZ - possibly with a dip switch.

For example - if using the 0-10V input - at 5V the PWM signal has DS of 50%.

Needs to be hardwired - not a programmable device. In some circles this would be considered a signal conditioner.
 
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Hi,
You can do this with a 555 timer and a comparator.

You configure the 555 timer to generate a sawtooth waveform, and you feed that waveform into the - input of the comparator, and then your DC voltage setting on the +. As you decrease the voltage level, the ramp voltage will hit it faster each cycle and turn the comparator off for a longer % of the cycle.

I don't know of anything fully qualified since this is a pretty simple circuit that anyone would just make probably.
 
Hello DP - Thanks - Yes I am sure to make one would be pretty basic, this is for a Power Electronics application where the components must be "Qualified Products" For us to do even a basic PCB and qualify it ~ 5 to $10K. Controlling a 100KW DC Power Supply application - where a Miss-operation would be a disaster.
 
Here is a circuit to do what I described.

You can ignore the output end with the 10k load, I used all of that for level shifting and protection only. If you use a single ended supply you would have less to worry about with that. The sine wave represents the adjustable DC voltage reference operating range. R1 and C1 set your frequency. The diode D1 shorts the high end of the resistor divider inside the 555 timer close to 0 to get fullest range.
 

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Windadct said:
Hello DP - Thanks - Yes I am sure to make one would be pretty basic, this is for a Power Electronics application where the components must be "Qualified Products" For us to do even a basic PCB and qualify it ~ 5 to $10K. Controlling a 100KW DC Power Supply application - where a Miss-operation would be a disaster.

Oh I see, then you'd definitely want to buy something already made or refine your own design a lot.

I'd say just use a modern signal generator, but that is not cheap itself. If miss-operation would result in disaster, I think this forum is not the right place to find your answers since someone fully qualified already should be making this decision. Something that is fully qualified never comes cheap.
 
Axiomatic makes the "www.axiomatic.com/current-pwm-converter.pdf" and the "www.axiomatic.com/TD2002AX.pdf" signal conditioners.
 
Last edited by a moderator:
Hello again - I think Dlgoff has provided a good product to consider - Thanks! I am pretty good at web searing but this has eleuded me - it is actually reference to my customer, we just make the power stages. I thought someone may have seen such an animal. As for the actual circuit and design - yes I did need a robust solution, so I was more looking for a reference to an existing product than circuit / design advice.

Thanks Again!
 

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