Load stand for testing generators, batteries and power supplies

Load stand for testing generators, batteries and power supplies

There is a need to test the hybrid power plant, I decided to make a stand.



12.05.2015
I need to test drive a load power of about 1000W.
Initially, I was checking operation of the generator resistor of nichrome wire, but this load is not appropriate to adjust the management and analysis of the characteristics of the power plant. Resistor resistance varies with temperature, the resulting current through the load is not constant, moreover, is difficult to make a variable load.
Therefore, as the load using the current stabilizer.

It was based on the article Methods of testing power supplies by Oleg Artamonov.

The idea is to use a MOSFET transistor as a controlled resistor.

But transistors also have the characteristics of dependence on the temperature, so use the feedback of current to compensate for thermal changes.

Many thanks to Oleg, he provided me with some ready various load modules from its stand.
Here is one version of its modules with three transistors

It's a little easier variant with two transistors

Oleg load modules were attached directly to the aluminum radiators.

The required power is achieved parallel connection of the modules.

However, to achieve the necessary power would take me 4-5 modules that are not associated to the power transistors, and limited heat resistance of the crystal / radiator.

I used a more thermally conductive copper radiator with heat pipe.

In addition, doubling the number of transistors on a three-transistor module.

This should allow to dissipate the required power using only one module.

Radiators are designed for computer processors, heat pipes are not allowed to make the mounting holes, had to do a kind of sandwich.

All components decided to mount in a ready case.

The control system is based on a ready board with a microcontroller - Arduino UNO.

By the microcontroller connected to an external DAC to set the load current and ADC for current and voltage monitoring. To operate in stand-alone mode (without a computer) using the keypad and LCD RGB display resolution of 320x240 diagonal of 2.4 ", as well as module FRAM 256 kb memory to store test results.

All components are interconnected by bus I2C.

In addition, the microcontroller is connected to the RPM sensor of the generator.

And outputs on motor control (electric motor or internal combustion engine), that rotates the generator.

Photos used components

The front panel will consist entirely of fans with a diameter of 80mm

External ADCs and DACs 

Three motor to be used as a generator and three-phase rectifier Schottky diodes.

Initially, the calibration of the system, the motor and the generator will be the same type to get the basic characteristics ...

28.07.2015 Made a synchronous three-phase rectifier.

This type of rectifier is to significantly reduce the loss of rectified current from low-voltage three-phase generator.
This rectifier used MOSFET transistors.