Tesla Switch Controller Board

Tesla Switch Controller Board

The Tesla Switch Controller is designed to interface to any of the SSR or IGBT driver boards, as it is equipped …read more

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Description

The Tesla Switch Controller is designed to interface to any of the SSR or IGBT driver boards, as it is equipped with matching connectors to provide both signal and power to each board. The remaining development work for this design includes the firmware coding and testing to verify the design. The final specifications and features for the system are as follows:

Designed for Any Battery Bank size
The current implementation can use any of the RG Solid-State relay switches, from the SSR3A up to the RG IGBT Drivers with PowerBricks, which allow just about any battery bank size to be controlled. The system is capable of monitoring banks with battery voltages of up to 48V.

0-1000 Hz Manual Frequency Adjustment
The system will include a rotary encoder knob that can be used to easily increment and decrement the switching repetition rate. Using the AVR-MT128 microcontroller’s internal timer, we can achieve a maximum frequency error of no more than ± 0.25 Hz. The frequency step size will be adjustable using the buttons and LCD screen which will display the current frequency output, and system activation status.

Isolated Voltage Measurements for Batteries + Output
The system includes isolated voltage measurement circuits which allow the controller to monitor the voltage across each battery, along with the system’s output voltage. These values can be read in real-time and outputted to the LCD and serial port for data logging and analysis.

The isolation circuitry provides power for the voltage measurement circuits to allow the controller to be completely isolated from any of the four batteries, preventing the Tesla Switch from being interfered with by ground connections and power draw from the controller. The use of a 16-bit Analog to digital converter allows precise measurements of the battery voltage with a resolution of 763 μV for a 50 V input measurement range.

Current Probe for Output Current Measurement
A Hall Effect current probe module can be connected to the outputto log output current and calculate the instantaneous power draw from the system. The current output can also be used to detect any faults that may occur while the system is running (short circuit, bad connections, etc.).

For the current sensor, either a 50 A or 100 A sensor can be used depending on the expected load draw on the system.With the 50 A sensor, the current resolution would be 763 μA and for the 100 A, it would be 1.5 mA.

System Status Print Output through Serial Port
This software feature can be enabled if sensors are used with the system. The controller also includes a simple set of IEEE 488 compliant commands to allow automated control of the system for testing and data collection. Examples of commands to read and write are:

  • Switching Repetition Rate
  • Battery Voltages
  • Output Voltage
  • Output Current

Auto Switchover to Power from System Output
This feature enables the controller to be self-powered from the battery switching system once it is in operation. According to the original design, the controller ran on a separate battery from the four that were being switched. In this case, a DC-DC convert is employed which can accept an input voltage of 18-72V, so if the output voltage is within this range, the system can be programmed to automatically switchover to the output.