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Does ClassD amplifier not suitable for 60Hz transformer? Answered

Hi there,

My application is in Audio range. I am going to use a Transformer instead of Speaker.

A 3- phase power calibration is my intention.

Similar to this link, https://us.flukecal.com/products/ele...wer-calibr...

My current AMP design might be class AB type. I am thinking how can I move class AB to Class D amplification.

A lot of the design effort relates to maintaining linearity and avoiding crossover distortion. 2 amplifiers( current, voltage) output will feed to CT and PT!

REQUIRMENTS :

1. The amp input should be plus and minus 7volt AC, 45-65Hz( 1 Hz has been converted to 1024)

2. Amp operating voltage should be more or less 24v. 3. 2 channel signal (not sure PWM) should be use , one for current, one for voltage.

4. Can run current transformer(input 16.5 V/1.5 A) and potential Transformer (input15v/2A).

5. If possible both voltage and current amplification is required in one IC.

6. Both positive and negative half signal should be amplify.

For CT, current transformer primary winding has 80turns, 16.5 V/1.5 A, secondary has 20Turns, 4.125v/6A output!

For PT, Potential transformer, Primary has 80turns, 15v/2A rating input, secondary has centertap! At secondary 960turns, 360v/0.332 A and 960turns 180v/0.166A output.

For the time being lets disscuss issues like,

1. Low frequency and high frequency phase shifts caused by a transformer will occur if the transformer is inside the negative feedback loop (when the output of the transformer provides the negative feedback). Then the amplifier must be compensated for these phase shifts.A transformer causes a phase shift at low frequencies caused by its inductance.

2. A product with a Class-D audio power amplifier (APA) driving an output transformer with inadequate low-frequency performance may shut down when its output is stepped from zero to maximum at the start of a sine cycle. Shutdown is triggered by short circuit protection (SCP), after the first half cycle of the sine output. The root cause is saturation of the transformer core.

3. Class D amplifiers approximate voltage sources, they won't take kindly into a CT load.

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