Zvs Function; Figure 24. Soft-Start Operation (On The Left) And Soft-Stop Operation (On The Right); Figure 25. Zvs Signal Versus Mains Voltage (Zoom On The Right); Figure 26. Parameters In Case Of Inductive Load (Example On The Right) - STMicroelectronics STEVAL-GLA001V1 User Manual

Triac gate
command
V
MAINS
All parameters (range, default value, unit, step, etc.) used to configure the load control for this mode are
described in Section 3.6 User
refer to Section 2.5 Hardware function
3.4

ZVS function

The ZVS (Zero Voltage Switching) function allows control of the loads in synchronization with the mains voltage,
which is especially useful for avoiding excessive dI/dt at turn ON that can damage the AC switches. The ZVS
signal versus mains voltage is shown below.
The real ZVS signal is not exactly synchronized with mains voltage due to component tolerance and delay. A
virtual delay "td_zvs" is implemented in the
problem. You measure it with an oscilloscope and modify the value through the user interface (for more details,
refer to firmware user manual).
In case of inductive load use, you must take into account the delay due to the
board and the phase shift due to the load. By adding these two delays, you can control the inductive load exactly
at the zero current crossing.

Figure 26. Parameters in case of inductive load (example on the right)

the "Final value" entered in "td_zvs" should be the difference between the "td_zvs" delay and the inductive load
delay. For example, "td_zvs" due to the STEVAL-GLA001V1 is 1000 µs, and inductive load delay is 2500 µs: the
final value is "td_zvs" – "inductive load delay" = 1000 – 2500 = –1500 µs.
In phase control mode, the "zcs_margin" parameter lets you avoid period overlap. This parameter should be taken
into account in "td" calculation: a half-period should be equal to the sum of "tp", "td" and "zcs_margin" as shown in
Figure 27. Parameters for phase control
UM2304 - Rev 3
Figure 24. Soft-start operation (on the left) and soft-stop operation (on the right)
tp_2
tp_1
td_1 td_2
td_(x-1)
Wait for next zero
voltage crossing
interface. For more details regarding the hardware components used for this mode,
description.
Figure 25. ZVS signal versus mains voltage (zoom on the right)
Figure 26. Parameters in case of inductive load (example on the right)
mode.
tp_(x-1)
tp tp
td td
NUCLEO-F030R8 development board firmware to counter this
shows an example of inductive load use:
UM2304
ZVS function
tp_1
tp_(x-2) tp_(x-1)
td_(x-2)
td_1 td_(x-1)
STEVAL-GLA001V1 evaluation
page 18/46