Variable Frequency Drive (VFD) devices have several different names. To name few; Frequency Converter, Adjustable Speed Drive, and Frequency Inverter. Some of these names are better describing the product and others are ambiguous and therefore confusing. The YL620-A by Yalang will be referred here as VFD.
This document shares guidelines and tips that are either not available or not clear in the official English user’s manual (YL620-A-Inverter-Manual.pdf).
To set a new value to a parameter follow the next steps:
STOP
key to make sure the motor is stopped. The internal fan will work for a short time. This allows the user to verify that the fan is functioning.P
). Do that using the DISP
(to scroll horizontally among the displayed digits) and UP
and DOWN
arrow keys to set the requested program group number.P
). Do that as described in the previous step.SET
key to enter the setting mode for the selected program group and parameter.DISP
(to scroll horizontally among the displayed digits) and ‘UP’ and ‘DOWN’ arrow keys to set the requested value.SET
key again to store the parameter in a temporary buffer (i.e., Inverter Host/Panel).-End-
shortly, and advances to the next parameter.PRGM
key again to leave the programming mode.Err 10
(i.e., ‘Power Disconnected’ message) will be displayed. After completing the transfer, the Inverter will turn off.u 1500
(i.e., u
for upload and 1500
for the last parameter scanned), and lock all keys, except for the PRGM
key. To return to normal mode press the PRGM
key. You can now continue using the Inverter as usual, however, the new parameters will become effective only AFTER a complete restart cycle (i.e., see Option 1 above). TBD: This last statement needs to be verified, as I have seen some parameters becoming active after using Option 2, WITHOUT the need for a complete restart cycle.Note: If instead of committing the recent changes you would like to rollback to the current permanent parameters stored in the Inverter Controller:
STOP
key, keep it pressed, and then press the DOWN
arrow key. The display will scroll through all the parameters and finally will display d 1500
(i.e., d
for upload and 1500
for the last parameter scanned), and lock all keys, except for the PRGM
key. To return to normal mode press the PRGM
key. You can now continue using the Inverter as usual.The Inverter may not have the default factory setting being active out of the box. It is suggested to start with restoring the factory defaults before setting any parameter.
To restore the factory defaults, set the following parameter (see the above Setting Parameters chapter for instructions):
P00.13 = 10
Notes:
The YL620 VFD (200VAC, 50Hz) is intended for use with a single phase input (Main Power) and three phase motor. The user’s manual does not mention anything about supporting a single-phase motor.
However, it can be connected to a capacitor-run single-phase induction motor with appropriate ratings.
Let’s start by a brief introduction to capacitor-run single-phase induction motors.
A capacitor-run single-phase induction motor has one capacitor, two windings (i.e., starting
and main
windings) mounted on the stator, and a cage winding placed on the rotor.
It may also have a centrifugal switch that disconnects the capacitor after the motor starts.
Following is a typical connection diagram of a capacitor-run single-phase induction motor:
Now that we understand how typical capacitor-run single-phase induction motors are connected, we will make the connection changes required to control it using a VFD with 3-Phase output.
The following steps are needed in order to connect this type of motor to this VFD:
starting
and main
windings) to the U, V, and W outputs of the VFD as follows:The motor can be operated in a jog mode (aka, ‘inching’), which allows to manually rotate the motor ‘inch by inch’.
To issue a jog command press the STOP
key, keep it pressed, and then press the DISP
key. The number of revolutions depends on the duration of the press. A brief jog can be less than one revolution. There is no upper limit to the number of revolutions (unless you have some sort of external range limit).
The direction of the jog is defined by the F/R
key.
There are several configuration parameters that define the jog motion:
In order to display RPM, there are two parameters involved:
The first (P00.23) is mandatory and the second (P00.24) is optional, as described in the following sections.
In order to display RPM, the ratio between the actual RPM and the Frequency, as provided by the VFD to the motor, at the point of interest (i.e., on the motor shaft or on the end spindle after a gear) needs to be known. This can be done by calculation (approximated by ignoring ‘slip’) or one-time measurement with an external device (accurate).
See Calculating the RPM/Frequency Ratio for details.
The RPM Strob
iOS App served me successfully to measure the actual RPM of my motor for several frequencies. See Using a Stroboscope to Measure RPM for details.
Once we have the RPM/Frequency ratio, we can set it as percentage [%] in P00.23 (Display Proportion Constant).
If you have a gear and want to display the RPM of the final RPM of the spindle after the gear, then you need to multiple the RPM/Frequency ratio with the gear ratio and use the result to set P00.23 (Display Proportion Constant).
At any time you can scroll through the display modes in a cyclic manner by pressing the SET
key. This is regardless of the value of P00.24 (Display Mode). There are 13 display modes, each showing different data. These modes correspond to the possible modes for P00.24 (i.e.,values 0-12). The order of the scroll matches the order of the modes values cyclically.
After setting P00.23 (Display Proportion Constant) we can display the RPM by scrolling the display, as described above, until we reach the “user variable” (indicated by lower case ‘u’ on the left digit). The displayed “user variable” is the result of multiplying the value in P00.23 (Display Proportion Constant) with the current Frequency provided to the motor, and this reflects the RPM at the point of interest (i.e., on the motor shaft or on the end spindle after a gear).
To set the “user variable” as the default display mode that will be shown when the VFD is turned on, set P00.24 (Display Mode) with the value 9.
Note that also with P00.24 = 9 (display user variable), you can still scroll through the various display modes in a cyclic manner, as described above.
The following examples were done with a YL620 VFD (200VAC, 50Hz) connected to a small (200VAC, 50Hz, 0.17A) capacitor-run single-phase induction motor. See Controlling a Single Phase Motor for details.
The basic parameters for the following examples are:
The above mentioned two parameters for displaying the RPM (also factoring the gear ratio) are:
In this case, when the motor runs the display will show the following messages depending on the speed set by the potentiometer:
For minimal speed: “u 400” For maximal speed: “u1000”
Please note that there is no decimal point in this example. I think this is a bug in the firmware installed on my VFD.
As a workaround I set the P00.23 to 20% instead of 200% and got:
For minimal speed: “u 40” For maximal speed: “u 100”
This refers to 40 RPM and 100 RPM, respectively. In this case they represent RPM which is 2 times the motor frequency.
Note that due to the decimal point presumably bug, P00.23 is set to 40% instead of 400%.
The displayed range now for the new scaling value is:
For minimal speed: “u 80” For maximal speed: “u 200”
This is exactly what I was looking for.
The approximated ratio between RPM and motor Frequency, while ignoring ‘slip’ is:
RPM [rev/min] = (120 x Frequency)/(#poles)
Notes:
For instance, if the nameplate specifies Base Frequency of 50 Hz and 1,425 RPM then,
Approximated #poles = (120 x Frequency)/RPM = (120 x 50)/1,425 = 4.21
However, the number 1,425 RPM is with ‘slip’. To find the synchronous RPM that corresponds to the Base Frequency, we need to find the nearest feasible value that gives an integer number of poles in the above formula. In this case, the synchronous RPM is 1,500 which gives #poles equals to 4.
The approximate ratio between RPM and Frequency is given then by:
RPM/Frequency = 120/(#poles) = 30
Now we know that for our example:
RPM = 30 x Frequency
Following is a simple equation for calculating Torque for given HP and RPM:
Torque [lb-ft] = (HP x 5252)/RPM –> Torque [N-m] = 1.356 x (HP x 5252)/RPM = Torque [N-m] = (HP x 7125)/RPM
Notes:
There are many free and paid stroboscope smart-phone applications on the app store. Some are relying only on the built-in flash, while others rely on external accessories, such as lights that are control via the audio jack of the phone. The RPM Strob
iOS App that uses the phone flash, served me successfully to measure the actual RPM of my motor for several frequencies.
Prepare a clear marker that can spin by the motor. I used a small rectangular piece of cardboard with a single radial marker line and attached it to the motor shaft.
Using any kind of Stroboscope, start with a flash rate higher than the estimated RPM and adjust the flash rate down. At some point you will stop the motion with only a single image of the object in view (e.g., a reference line).
For a single reference line spinning by the motor at 1,500 RPM you can see:
#Lines | Flashing Rate | Comment |
---|---|---|
4 | 6,000 RPM | Harmony of 1,500 RPM |
3 | 4,500 RPM | Harmony of 1,500 RPM |
2 | 3,000 RPM | Harmony of 1,500 RPM |
1 | 1,500 RPM | Actual motor speed |
1 | 750 RPM | you see the line only half times |
As can be seen from the above table, the actual RPM is the one showing only one line and if you double that flash rate you will see two line. For instance, in the table above, 750 RPM is not the actual RPM, because when you double it you get 1,500 RPM for which you still get only 1 line. However, 1,500 RPM is the actual as it fulfill the two conditions.
For more details see this short article on Using a Stroboscope to Measure RPM.
The optional braking resistor consumes the regenerating energy of the motor and shorten the ramp-down time.
The braking resistor can be connected to the ‘+DB-‘ connectors of the Main Circuit Terminals.
The following recommendations are based on the user’s manual:
Based on the user’s manual:
Set the P00.03 program group and number to the value of 2. For details on how to do that, see the Setting Parameters section above.
As an experiment, the following steps on were performed on a Yalang YL620 (200VAC, 50Hz) VFD:
RUN
to start the motor and wait until the motor reaches its final speedSTOP
to stop the motorRUN/STOP
cycle at different RPM)RUN
to start the motorSTOP
to stop the motorThe YL620 VFD supports several configurations to control the behavior of the DC Braking (e.g., P01.09-P01.15, P04.04, ). However, in this experiment, their default values were used.
Note also that the over current error message ER02
has a dedicated value of 7
indicating: “DC braking is too high. Decrease DC braking”.
The Detachable Control Panel of the YL620 is connected using 4-wires, uncrossed flat cable (15 cm long). The cable is connected on each end to a PCB mounted JST-XH Top Entry type pin header (2.5 mm pitch).
The 4-wires are:
The A and B wires are the UART Tx/Rx of the MODBUS protocol using 8 control bits, 1 stop bit, no parity. This was discovered by using a Logic Analyzer (i.e., Open Bench Logic Sniffer board with PulsView software). However, it is unclear if it is a standard or modified MODBUS protocol.
The following open questions are in addition to those on the parameters excel sheet: