Functional Description; Phase Angle Control; Full Wave Control - STMicroelectronics STEVAL-IHT005V2 User Manual

Functional description

4 Functional description
Two different types of ACS/Triac control are implemented. Phase angle control and full
wave control. The gate control signal is synchronized with zero voltage crossing signal
(ZVC). The MCU operation is also synchronized with ZVC signal. ZVC signal is sent directly
to the MCU input pin that is set as external interrupt.
4.1

Phase angle control

Control of T1 (T1635H) and T2 (ACST16) is based on phase angle control.
Phase angle control is based on changing the firing angle (delay). The firing angle
determines the power that is delivered to the load. The shorter the firing angle (delay), the
higher the power.
Firing angle and gate control pulse are defined by software.
firing angle.
Firing angle (delay)
4.2

Full wave control

Control of T3 (Z0109), ACS1, ACS2, and ACS3 (all ACS108-8S) is based on full wave pulse
control.
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Figure 4. Phase angle control description
Table 1. Firing angle delay
Level 1 Level 2
8.5 ms 6.9 ms
DocID024503 Rev 1
Table 1 shows initial setting of
Level 3 Level 4
5.2 ms 3.6 ms
UM1631
Level 5
2.0 ms