Novak Power Capacitor

NOVAK ELECTRONICS POWER CAPACITOR

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During normal operation of any high current radio-controlled ESC, the PWM control of the motor power produces an alternating voltage waveform (or ripple) onto the battery voltage. The amount of ripple current is dependent on the inductance of the motor. This means that a lower turn motor will produce a higher value ripple current.

Shown: #5679
GTB Power Trans-Cap Module.

A large power capacitor (Novak power capacitor) is used to smooth this ripple out so that the average voltage available to the ESC is close to the battery voltage. This serves to not only protect the ESC electronics, but will also increase the RPM's available during partial throttle.

The ripple voltage produces a charging and discharging action on the capacitor and the resulting ripple current will generate heat inside the capacitor.

The power loss associated with this ripple current is defined by:

P=I²R

where:

P=Power Loss (Watts)

I=Ripple Current (Amps)

R= Effective Series Resistance (Ohms)

The maximum power a capacitor can handle is dependent upon the surface area of the capacitor. A bigger sized capacitor can normally handle a higher ripple current. Keeping the capacitor cooler by both heat-sinking and forced air cooling will aid heat transfer which will allow for higher ripple current capability.

Another important property that comes into play is the internal resistance of the capacitor, know as the capacitor's ESR value. Lower ESR values are desirable. A capacitor with Low ESR and high ripple current capability such as those used Novak will make your car have more punch and make your ESC run cooler.

Ideally the power capacitor should be mounted as close as possible to the ESC to keep the connection resistance as low as possible. The #5679 GTB Power Trans-Cap Module that is factory-installed on the GTB ESC is wired using 16-gauge wire so the module can handle the required current without inducing too much voltage drop between the capacitor module and the ESC. Therefore the power capacitor's wire length should be kept to a minimum for maximum efficiency.

Shown: #5679 GTB Power Trans-Cap Module.

Many Novak racers use two power capacitors or two power capacitor modules in parallel to obtain the highest possible performance. The Novak capacitor modules have more than just a power capacitor, we have also included on this module two Transient Suppressors and three High Frequency Decoupling Capacitors. The two Transient Suppressors act like a voltage clamp and prevent high voltage spikes from damaging the ESC, and the three High-Frequency Decoupling Capacitors filter out radio interference noise.

So, the Novak capacitor is not just any power capacitor. Novak specially selects capacitors with very low ESR values with the highest possible ripple current for the capacitor that size.

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