Week 15 : Success in Controlling MX45-3Pi Power Supply

 We manage to solve all the problems we encounter last week with the new driver from CAPRA bench. These are the VIs necessary for our programming.

This is an example of CONFIGURE ALL VOLTAGE VI, the string INST:COUP ALL is required to control all the 3 phase voltages together. We were unable to access the low level VI previously but with this new driver we are able to access and modify low level VI within the driver.

 This VI is used to control the slew rate of all 3 phase voltages.

We configure the voltage slew rate to 20V/s for safety purposes. When we  enable the output it will delay for 0.5s before ramp up the 3 phase voltages from 0 to 235V with a rate of 20V/s . Case structure is used to select the value of output voltage automatically when the users selects the program.

This portion enables the power supply to reduce to all the 3 phase voltages to 0V and disable the output automatically. In order to ramp down the voltage to 0V in exact time, we create 2 local variables: #3 VOLTAGE 1 OUTPUT LIMIT (from the diagram below) & RATE (3rd diagram) and change it to read. After that we use  #3 divide by RATE  and plus 1.5 to get the total delay time before disabling the output so that the voltage can reach 0V before the output is being disabled.

After that we combine our power supply software with the 3 instruments software for testing, the results are shown below :

Note: The above result is not from the latest program. We have finish our main program and will test it out when the bench is available.

Setting up GATU :

Week 14: Design of Ramp Up/Down Voltage and Troubleshooting

 

These are the problems we encounter when we program the slew rate for power supply :

1. All the 3 phase voltages are unable to respond at the same time.
2. Users have to press the "UPDATE" button 3 times to increase/decrease all the 3 phase voltages.
3. A specific amount of delay time must be introduced so that the slew rate work perfectly.
4. It will increase/decrease the voltage phase by phase which is undesirable
5. The built file cannot be executed on the other computer

 All these problems are caused by the driver we downloaded from the 3rd party website, which is the California Instrument, Ametek Programmable Power website as LabView doesn't develop this driver. It's tough for us to troubleshoot the problem as the test bench is always in used, hence it is time consuming for us to solve the problem. However we are closed to solving the problems above.

 

Our task this week is to configure the power supply so that it will increase the voltage slowly to 235V with a slew rate of 20V/s. We have faced a lot of problems with this features.

At first, we program it in such a way that  it enables the output first before load in the voltage value. However this cause the output ramp up phase by phase which is undesirable.

The main culprit of the fault is time. The value must be loaded into the VI before enabling the output so that all the 3 phase voltages can ramp up together. However, this leads to another problem which is all the 3 phase voltages ramp down phase by phase with a great amount of delay in between it.

We are still troubleshooting the problem and try to solve it by next week.

Week 13 : Configuration of Voltage Range

 

The default program for power supply - Voltage Range 150 V.

•  For ATU/GATU , we need to supply 235 V to each phase. With the Voltage Range 150V is being set by default, the max voltage can only supply up to 150V. 

• Hence, we are required to configure the VOLTAGE RANGE to 300V.

 

This is the VI  that we use to configure the VOLTAGE RANGE.

 

This is how we connect the VI in the program to improve on it. 

 

 After we set the VOLTAGE RANGE to 300 V, the power supply put itself into HI RANGE mode which will activate its RELAY internally to support the flow of high voltage.

• The switching of the RELAY produces tremendous noise which interfere the communication and data acquisition between each instruments and therefore interrupt the program.

• Therefore, we decided to use this FLAT SEQUENCE STRUCTURE to arrange the flow of each part of programs.

• We arranged the program of power supply in the SEQUENCE 1,so that when the program runs,it will first finish initializing the power supply and switching of relay to HI RANGE, then only start to initialize other 3 instruments.

• In between, we added in some buffer time before the program start to initialize the 3 instruments.It is 5 seconds.

• Below is the VI and how we connect the TIME DELAY in the program.

Week 12 : Execute Button

                                  

 

We have improved our front panel appearance for power supply as shown in the diagram above.

• As for safety purposes,we added in one EXECUTE BUTTON for each of the programs to prevent some careless mistakes make by operators such as typo like 235 V to 2350 V.

•  With this EXECUTE BUTTON, it acts like ENTER,every time after we edit the voltage level for each phase,it is necessary for us to press the button to call out the voltage from power supply.  

Here is the example of careless mistake might make by the operators - accidentally set the voltage to  2350 V. 

• With the absence of EXECUTE BUTTON, the power supply will directly supply 2350 V which causes overheating and damage to the power supply.

• Besides, we added in the VOLTAGE OUTPUT LIMIT at the right side to have double safety protection.We set the maximum voltage output limit to 270 V.

 

This is how the EXECUTE BUTTON"s block diagram looks like.We put it into a event structure so that the program will wait for user to press the button first, then only it will load the voltage.

 

For every EXECUTE BUTTONS , we set their MECHANICAL ACTION to LATCH.

When the user press the button, it executes, the green light indicator lights on, until it finish executing,the indicator lights off.

Week 11 : Design of California MX45 - 3Pi Power Supply

At first we are asked to program the Pacific Power Source but that model is the only power supply in Singapore. Therefore we change from Pacific Power Source to California Power Supply, which the company has 2 units.

 
The way we program the California Power Supply is similar with the Pacific Power Source.

 These are the VIs we use to program the California Power Supply.

This is the front panel of our program. First select the Program you want (the programs are arranged according to Acceptance Test Procedure), after that press the OUTPUT DISABLE BUTTON so that it becomes green colour OUTPUT ENABLE.
 After that the voltage and frequency can be control through the blue box above. We'd also set the max voltage limit to 350V and current limit to 40A.

 For example, if we select program 4, the gauge will display the program that is in action and the tab control will switch to program 4 automatically.

Due to some issues with the driver, we can only run this program in the desktop with LabView installed. We are asked to solve this problem so that this program can be run in the ELS desktop too.

Week 10 : Acquisition speed improvement and Pacific Power Source

• Due to the time consuming on exporting the required data to the excel file for 3 instruments,we are asked to make improvement on it.We came out with an idea of storing all the data into local variables, so that every time we run the program,the data will store in the local variable as standby mode until we call it out by pressing the ACQUIRE button.By doing so, it is efficient as the data will export directly to the excel file.

• First, we created a local variable on the data we need to export e.g. VOLTAGE (V3) in the above diagram. This step goes to all the data that required to export.

 

• What we need to do next is to change the local variable we created which looked like a home icon in the above diagram to READ.

  

• Diagram of how we connect the local variables in POWER METER (Short-circuit test) .

• Diagram of how we connect the local variables in POWER METER (Open-Circuit test). 

 

• Diagram of how we connect the local variables in OSCILLOSCOPE.

 

• Diagram of how we connect the local variables in MEASURE UNIT.

• For all the 3 instruments,we have improved them by creating a event structure and put the ACQUIRE and EXCEL program part into it which shown in the diagrams above.The way of connecting the local variables for each of them are similar,just they will be exported to different roll & column.

 

• For both Short-circuit and Open-circuit test,it is absolutely necessary for us to put in the time duration to alert the operator to prevent the ATU unit from overheating.The maximum time for it is 4 minutes.Once it reaches 4 minutes, the program will alert the operator by turning the icon RED. 

 

• This is how the front panel looks like for the OSCILLOSCOPE page in tab control. In the diagram above, the LIGHT GREEN colour icons show the readings are passed and in phase.They will turn RED if the readings are out of range.

• At first,we decided to put the left portion in the diagram above( POWER SOURCE) in one page and put the right portion (POWER METER)into another page,but to make it user friendly and convenient for the operator,we decided to put both of them in one page, so that the operator can directly observe and key in the data they want.

•  For the RED bubbles above,they are used to determine whether the readings are in range or out of range.RED is failed and GREEN is passed.

• The PHASE 1 for our project is considered done, what we need to do is to continue collect feedback from the operator and improve on it .According to the Gantt chart, it is necessary for us to start with PHASE 2 - Control of Power Source.

 

• This is how the front panel of POWER SOURCE looks like. On the right tab, we fixed the parameters for 6 programs with different settings required by the operator.

• Every time the operator run the program,he need to choose a program on the left side of the diagram based on which test they are going to use, for example : short circuit or open circuit.

• The middle tab is use to control the output voltage according to the POWER METER to ensure the output voltage of 3 phases are in range.

 

• Since we have 4 while loops, this QUEUE function is use to communicate between each loops.It is necessary for us to control these loops using single button.