DRV103: DC Solenoid PWM

==more information==

-- expectation value (Simulation Data) 

-- Test value  -- Current Value is Zero

Hello, 

Could you please provide your schematic? 

Best Regards, 

Elizabeth 

Hello, 

This is our schematic

please check it

Thanks,

Hi Gilho, 

Based on your surrounding circuitry, we would expect the following typical values: 

I have also added the calculator I put together to determine these values. 

1565.DRV103 calculator.xlsx

Apologies for needing another clarifying question, but it is unclear what is being measured in the plots you've shared. It is additionally difficult to determine the time scale of each of those plots. Could you label the plots and unclip the photo to show the timing per division. 

What you can do is check whether what you have calculated lines up with what I have in the excel document. 

Is the issue that the output current draw is 0? For how long is this occurring after start up? 

Best Regards, 

Elizabeth

Hi, Elizabeth

The values you mentioned are consistent with what I intended, excluding Duty. I designed the duty to be around 30%.

I will provide more details about the parameters. This waveform is obtained through simulation. Since the simulation was pefrormed using only simple R and L components, we can ignore the initial transient portion.

[Total Graph] - 0~200ms

/resized-image/__size/640x480/__key/communityserver-discussions-components-files/196/_04C8B4CC0CD315D6_.png

[PWM Graph] - 100~104ms

/resized-image/__size/640x480/__key/communityserver-discussions-components-files/196/2068.PWM.png

Cycle : 1ms , Duty : 0.3ms,  Current : 0.4~0.5A

We want to obtain this data.

But, Test data is a follows.

[Total waveform]

/resized-image/__size/640x240/__key/communityserver-discussions-components-files/196/6862.scope_5F00_67.png

[PWM waveform-1]

/resized-image/__size/320x240/__key/communityserver-discussions-components-files/196/5857.scope_5F00_68.png

[PWM waveform-2]

/resized-image/__size/320x240/__key/communityserver-discussions-components-files/196/4300.scope_5F00_69.png

Delay Time :89ms, Cycle :5.48ms(182.48hz), Duty : 0.38ms, Current : 0~0.17A

Based on the waveform, it appears that the current should reach zero for the cycle to progress.

Other waveform is same.

please check it

Thanks,

Hi Gilho, 

I am looking into this and will have a response for you tomorrow. 

Best Regards, 

Elizabeth 

Hi, Elizabeth

Thank you for your appreciation.

I have uploaded the requested test waveform again.

I see that there is a difference between the waveform shown and the simulation waveform, despite using the same load. However, the test was conducted using the DRV-103, while the simulation utilized a simple RL load with PWM source.

The simulation circuit and the test circuit are as follows

                                              [Simulation Circuit]                                                                                        [Test Circuit]

PER - Cycle 

PW - Duty

As you understand it, the test board behaves differently from the intended design by completely dissipating the energy until the current reaches zero before the device is reactivated.

This phenomenon occurs consistently regardless of changing the duty cycle from 30% to 90% or altering the PWM frequency.

What I understand from your question is whether the DRV-103 requires the inductor current to reach zero for the device to be reactivated.

Is it necessary for the DRV-103 to reach zero current for the device to activate?

If not, what other aspects should I verify?

The solenoid is not being maintained due to the mentioned phenomenon. Although you may be busy, I kindly request your review.

Thank you. Elizabeth

Based on my understanding, it seems that the reason for the longer period is because the current needs to reach zero for the device to activate.

Even with an initial startup current, it can be observed that the current must reach zero before proceeding with PWM.

The intention of this design is simply to drive a DC solenoid. Initially, a large current is required, so a delay is introduced to maintain it, and once the solenoid is engaged and the plunger contacts the core, a large current is no longer necessary. PWM is used to limit the current value in this case.

To drive any solenoid, current needs to flow through the coil, and it is necessary to keep the inductor charged. If the energy is dissipated and the device is activated again, the solenoid will return and the maintenance will not be possible.

To be precise, the current should not drop to zero during PWM control.

The DRV-103 is also designed for solenoid driving applications and therefore needs to perform these functions.

Please confirm.

Thanks, Elizabeth

Hello, 

Thank you for elaborating on your intended use case. 

Can you confirm this behavior is occurring across multiple devices? 

Best Regards, 

Elizabeth