Programmable Inrush-current limiter Alfredo ARNO Cyril BORCHARD Programmable Inrush Current Limiter Simple implementation w/ digital control Inrush current limitation Programmable soft-start High efficiency solution MCU MCU SCRs TRIAC VAC C Improved reliability VAC C High power density < 500 W > 500 W Line-drop recovery Simple implementation Mixed-bridge example 2 x SCRs used in progressive start-up mode or bypass mode Ex: TN5050H-12WY 85 VAC to 264 VAC 45 Hz to 65 Hz 32 A RMS max EMC filter Compliance with: EN55015, IEC61000-4-11, IEC61000-3-3 IEC61000-4-5, 4 kV IEC61000-4-4 EFT burst: 4 kV min Stand-by losses < 300 mW 2 x low-VF high-voltage diodes Ex: STBR6012WY 1 MCU used to drive the SCRs and for the digital-control of the PSU 2 x opto STM8S MCU PFC controller Programmable soft-start Mixed-bridge example T2 T1 • Operation : VAC HVDC • Bulk capacitor charged smoothly thanks to phase angle control of the SCRs HVDC VAC • T1 and T2 synchronized according to the zero crossing (ZVS) of the AC line SCR1 SCR2 ∆t T T_OFF_2 T_OFF_1 T_OFF_Max T_OFF_Min 3x∆t 2x∆t T T_OFF_3 T 4x∆t T 5x∆t T T T Inrush current limitation Mixed-bridge example S2 S1 VAC IAC_RMS = 6 A C RLIM Inrush current limited by PTC Charge time = 400 ms IAC (10 A/div) IAC (10 A/div) VAC VDC IAC_RMS = 6 A VAC T1 VDC HVDC VAC T2 HVDC Inrush current limited by SCRs phase control Charge time = 120 ms while complying with IEC61000-3-3 Efficient Analysis Stand by power losses On-state power losses 150 W application On-state power losses 200 W application Dissipated power: Coil = 0.4 W (G5 relay) Dissipated power: Coil = 0.4 W (G5 relay) RL1 closed Power losses = coil consumption Contact resistance: P = RI²=0.1*(150/230)²= 42.5mW Contact resistance: P = RI²=0.1*(200/230)²= 76 mW Bridge: PD = 482 mW Bridge: PD = 649 mW 400 mW Total dissipated power: 924 mW 0.62 % of total Total dissipated power: 1125 mW 0.56 % of total Triac: PD = 534 mW Triac: PD = 701 mW Bridge: PD = 482 mW Bridge: PD = 649 mW Total dissipated power: 1016 mW 0.67 % of total Total dissipated power: 1350 mW 0.67 % of total No heatsink required No heatsink required Type RL2 150W application: RL1 VAC Energy consumption – 1 hour (50% stby + 50% on) RLIM C TRIAC VAC T1010H-6G C gate current still applied 50 mW 0.69 Wh 200W application: 0.76 Wh 150W application: 0.53 Wh 200W application: 0.7 Wh Efficient Analysis Energy consumption - 1 hour (50% stby + 50% on) Stand by power losses On-state power losses 500 W application On-state power losses 1.1 kW Application RL2 Dissipated power: Coil = 0.4 W (G5 relay) Dissipated power: Coil = 0.4 W (G5 relay) RLIM RL1 closed Power losses = coil consumption Contact resistance: P = RI²=0.1*(500/230)²= 472mW Contact resistance: P = RI²=0.1*(1100/230)²= 2287 mW Bridge: PD = 1707 mW DBridge: PD = 4131 mW Total dissipated power: 2580 mW 0.51 % of total Total dissipated power: 6818 mW 0.62 % of total Diodes: PD = 923 mW Diodes: PD = 2167 mW SCR: PD = 878 mW SCRs: PD = 2089 mW 0.9 Wh Total dissipated power: 1801 mW 0.36 % of total Total dissipated power: 4156 mW 0.38 % of total 1100W application: No heatsink required No heatsink required Type RL1 500W application: VAC C 400 mW SCRs VAC TN1205H STTH8L06 C gate current still applied 25 mW 1.49 Wh 1100W application: 3.61 Wh 500W application: 2.08 Wh Reliable 5 A Relay 175,000 operations < 10 Years 5 A relays for 1.8 A load 10 A Relay 500,000 operations < 10 Years 10 A relays for 0.5 A load ! SCRs and Triacs being semiconductor switches No ageing effect High power density Relays: 60 mm x 20 mm Triac + heatsink: 25 mm x 20 mm Line-drop recovery Mixed-bridge example AC line voltage interrupt lasts more than 30 ms SCRs are controlled back in soft-start when the VAC is reapplied, criteria B AC line voltage interrupt lasts less than 30 ms SCRs are kept “ON”, criteria A VDC VDC VAC VAC IAC VAC SCR1_CTRL AC line voltage dips with a 0% residual voltage applied during 20 ms – Pout = 1kW IAC SCRs C SCR1_CTRL AC line voltage dips with a 0% residual voltage applied during 40 ms – Pout = 1kW