How can I get/build a current controller/amplifier?

Question

Background:
I have a Lorenz-actuator (coil+magnet) that I need to control precisely using a computer. The computer signal is output from a dSpace microLab box as an analog ±10V signal. This signal needs to be scaled to a current of ±5A at roughly 24V. Given the phase shifting properties of coils as well as the underlying physics of Lorenz-actuators, the output current needs to follow the input signal. The system being controlled is highly dynamic and therefore requires a very accurate step response from the current controller. (Perfect tracking up to 200Hz) Four of these actuators need to be controlled so price and size are a factor to consider.

Attempted solutions:
Using a shaker current amplifier: Shakers cant handle any DC, therefore the amplifier has irremovable high-pass filters. My application requires some DC-component in the signal. The ones available to me are also very large and expensive.

Using a voltage amplifier and hoping for the best: Not getting the desired force trajectory from the actuator because current is not being controlled directly. Also can't tune the PID parameters of the control loop.

Using a current controller: I haven't been able to find any online that can drive a current of 5A dynamically. A constant current source is not useful for this application.

Using elmo servo drivers: The output current follows the input signal perfectly, however the drives are completely overkill. They are meant to take a digital signal and control the velocity, position and current of an actuator. Using them as an analog current amplifier is a waste of money.

Question:
Does anyone know of an off-the-shelf solution to control the current to the actuator? Or possibly a paper describing how to build a circuit that could amplify an analog current signal?

Answer 1

^{simulate this circuit – Schematic created using CircuitLab}

Class D audio amplifier would be a good choice. The one that you can eliminate the blocking capacitor at the input. Your current requirement seems to be a close match for what an D class amp is made for.

But, the audio amp would amplify the voltage in certain relation. It compares input voltage and feedback voltage at amps output. Not a voltage to current converter.

You should put a shunt resistor in series to a load, then measure this current and close the loop with a P controller - supposing that you have successfully eliminated the DC blocking capacitor at the input. You would need an opamp, a small dual power supply and couple of resistors.

EDIT:

The current is measured with Rsh. A voltage drop is created on this resistor Vsh=I*Rsh. This voltage is then filtered with a low pass filter 1kohm + 100nF. Without R6 mounted, the loop gain is very high and could make the whole thing unstable, you should adjust the gain. You could use also one another opamp to separate the LP filter and gain setting.

IRAUDAMP9 no blocking capacitors at input signal

This is a schematics of IRAUDAMP with IRS2092, you will find many cheap boards with this setup, most of them require strictly the voltage power supply as declared. Instead of the speaker, you should attach your load. The ground has to be the same for IRAUDAMP and for the P controller.

^{simulate this circuit}

Fixed LP filter and separate gain setting:

^{simulate this circuit}

EDIT2 :

Supposing the input and output voltages are out of phase by 180 degrees. You can see that both are summed by inverting input of opamp in IRS2092, so the conclusion is that they are shifted, and so the current is also shifted. The P controller has to get new shape:

^{simulate this circuit}

You might need to attenuate the +/-10V setpoint value to a lower value also to fit to the amplifier input voltage:

^{simulate this circuit}