Closed Loop Class E

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Closed Loop Class E

Postby atluri » Thu Jan 19, 2006 9:53 am

Hi Guys,
I am trying to develop a class E power amplifier as a driver for inductive link power transmitter in biomedical applications. Basically I have two coils for power transfer and receival. I am driving the transmitter using class E.
Now I wanna design a closed loop class E power amplifier bcoz the class E gets detuned when the secondary keeps moving away or towards the primary. It would be great if someone could help me in this direction

Suresh
Thanks

Atluri
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Re: Closed Loop Class E

Postby steve_qix » Thu Jan 19, 2006 11:44 am

atluri wrote:Hi Guys,
I am trying to develop a class E power amplifier as a driver for inductive link power transmitter in biomedical applications. Basically I have two coils for power transfer and receival. I am driving the transmitter using class E.
Now I wanna design a closed loop class E power amplifier bcoz the class E gets detuned when the secondary keeps moving away or towards the primary. It would be great if someone could help me in this direction

Suresh


How quickly does the rig have to respond (how quickly does the load change?).

Regards,

steve
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Postby atluri » Thu Jan 19, 2006 11:51 am

Hi Steve,
It doesnt change that quikly.It would be around a second or so.
My operating frequency is 1MHz.
Closed loop class E control methods have been discussed in some journals.but my problem, the journals have given only block diagrams without circuit details for the closed loop.so im trying to figure out some circuits for that.
Also have any of you used 555 timer before. I wasnt able to get the subckt for the LMC555 timer chip to include in my simulations. It would be great if someone can help me.
Thanks

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Postby frank carcia » Thu Jan 19, 2006 9:35 pm

I wonder how much power you are running. a low power final could be tuned with varactor diodes with the control monitor of the dc current.
back to back diodes would cancel the effects of the waveform. A higher power unit may require a stepper motor on a vacuum variable cap.
I would think drain current would be an easy to monitor the status of the load Z resistive. A reactive load change could be another problem depending on the phase change. This might require a return loss coupler on the output to monitor power and phase of the forward and reflected power. Then it would be a matter of making a automatic tuner like an automatic antenna tuner with enough range to cover the complex load change. Again it could be varactors or stepper motors on a variable cap depending on the powr level. Check out the latest QEX there is a cool article on an automated Power/SWR monitor. A few issues back a guy had a good article on measuring phase related loads. fc
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