12. AC Input Module (AIM / MI-AIM) Design Guide & Applications Manual For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies OVERVIEW In combination with VI-200 and VI-J00 Family of DC-DC converter modules, the Alternating Input Module (AIM) provides a high density, low profile, universal AC input off-line switching power supply for systems requiring up to 200 W of total output power. The AIM accepts 85 – 264 Vac, with a DC output voltage proportional to the peak value of the AC line. The input voltage required for the AIM to start operating is between 82 V and 90 Vrms (non-distorted sinusoid). The DC output of the AIM is the peak rectified line (Vac RMS X √ 2 ), thus, 85 Vac corresponds to 120 Vdc and 264 Vac corresponds to 373 Vdc. Since the DC output range is wide, a “7” (100 – 375 V) designator for input voltage in the part number of the DC-DC converter is required. However, the “5” (100 – 200 V) designator for the DC-DC converter part number is available for domestic AC inputs only and the “6” (200 – 400 V) designator for European AC inputs only, potentially reducing the number of modules required in some applications, based on output power capability. Input overvoltage conditions cause the GATE IN pin of the AIM to disable the converters when the output bus voltage is in the range of 406 – 423 Vdc. Input undervoltage conditions cause the GATE IN to disable the converters when the output bus voltage drops within the range of 68 – 89 Vdc. CAUTION: The AIM is not isolated. Do not place scope probes on input and output of AIM simultaneously. Do not connect the output of the AIM to earth ground. The GATE OUT of the AIM must be connected to the GATE OUT of only one DC-DC converter. This input signal to the AIM controls a charge pump (D1, D2, C2) that biases the gate of Q1, 10 V above its source, which turns on Q1 to shunt out a PTC thermistor that limits inrush. Multiple DC-DC converters operating from an AIM may make it difficult to guarantee a 10% load on the DC-DC converter that provides the GATE OUT signal to the AIM . In this instance, other DC-DC converters can charge pump the FET through the PARALLEL pin, with the addition of two diodes and a capacitor to each Driver module. (Figure 12– 4) SUMMARY OF COMPATIBLE DOWNSTREAM DC-DC CONVERTERS Use VI-x7x for inputs of 85–264 Vac; VI-x6x for inputs of 170–264 Vac; or VI-x5x for inputs of 85–135 Vac. EMC filtering specifications of FCC Level A are met by adding a 0.47 µF “X-type” capacitor to the input of the AIM (Vicor Part #03047); “Y-type” bypass capacitors must also be added from the +/– inputs of the DC-DC converters to their respective baseplates, which are grounded (Vicor Part #01000, 4,700 pF). To select the hold-up capacitor appropriate for your application, (refer to Selecting Capacitors for AIM Modules section that follows). The output ripple of the AIM is a function of output load. It is necessary to keep the ripple less than 20 V p-p to ensure the under / overvoltage protection circuits will not trigger. A fully loaded AIM (200 W of module output power) requires a minimum of 680 µF of capacitance; hold-up requirements can be met with this capacitor and maximum total capacitance should not exceed 1,200 µF (refer to Selecting Capacitors for AIM Modules section that follows). The voltage rating of this capacitor will be determined by the input operating voltage. It is necessary to connect all “Driver” DC-DC converter GATE IN pins to the GATE IN pin of the AIM . This GATE IN to GATE IN connection is used to disable the converters at turn-on to allow proper start-up of the AIM . The DC-DC converters are then enabled through the GATE IN pin when the output bus voltage is in the range of 113 – 123 Vdc. VI-200 and VI-J00 Family Design Guide Page 33 of 98 +OUT L1 Q1 Vref 1 U2 OV EMI Filter D2 C2 GATE OUT 10 V D1 PARALLEL Vref 2 OC Level Shift GATE IN Q2 U1 –OUT L2/N Figure 12–1 — Block diagram, AIM / MI-AIM PIM 0.47 µF L1 VI-AIM AC IN L2/N [a] POM +IN +OUT [a] C1 –OUT +OUT DC-DC CONVERTER –IN LOAD –OUT C1 is a hold-up capacitor necessary for proper operation of the AIM. Hold-up capacitors are available at vicorpower.com. Figure 12–2 — System block diagram (supervisory connections not shown) Rev 3.5 Apps. Eng. 800 927.9474 vicorpower.com 800 735.6200 12. AC Input Module (AIM / MI-AIM) Design Guide & Applications Manual For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies SELECTING CAPACITORS FOR AIM MODULES Hold-up Time. For maximum flexibility, an external capacitor (Figure 12–2, C1) is used to set the system’s hold-up requirements. Hold-up time, for purposes of this application note, is defined as the time interval from loss of AC power to the time a DC-DC converter begins to drop out of regulation (Figure 12–3, T4 to T5). Hold-up time is a function of line voltage, hold-up capacitance, output load, and that point on the AC waveform where the line drops out. For example, if the AC line fails just after the hold-up capacitors were recharged, hold-up time will be much greater (Figure 12–3, T3 to T5) than if the AC line fails just prior to another recharge (Figure 12–3, T4 to T5). The basic equations involved in calculating hold-up time are: 1 X C1 X Vp2 – 1 X C1 X Vdo2 = PIM X (T5 – T3) 2 2 (1) solving for C1: C1 = 2 X PIM x (T5 – T3) Vp2 – Vdo2 (2) Where PIM is power delivered from the AIM: POM PIM = Module Output Power = Module Efficiency Eff. % / 100 RECTIFIED AC (3) The energy (Joules) delivered from the AIM from the time power is lost (T4), until loss of an output (Figure 12–2, T5): Vp Vv Vdo Energy (Joules) = PIM x (T5 - T4) (Watt – Seconds) T0 T1 T2 T3 TIME T4 T5 (4) where: POM = Output power from all the modules PIM = Input power to the modules (output power from the AIM) Figure 12–3 — AC waveforms Eff = Weighted average efficiency of all modules The input power to the converter(s) during normal operation is supplied from the AC line during the conduction time of the rectifiers (T2 to T3) internal to the AIM and by the energy stored in C1 when the rectifiers in the AIM are reverse biased (T1 to T2). In the event of an AC failure (T4), C1 must continue to provide energy to the converters until either AC returns or the converter drops out (T5). The energy stored in C1 at the peak of the AC is: 1 x C1 x Vp2 = Joules 2 (5) The energy stored in C1 when the converter drops out of regulation is: 1 x C1 x Vdo 2 = Joules 2 (6) The energy delivered by C1 to the converters during normal operation is: PIM x (T2 – T1) = Joules VI-200 and VI-J00 Family Design Guide Page 34 of 98 Rev 3.5 Apps. Eng. 800 927.9474 vicorpower.com 800 735.6200 (7) 12. AC Input Module (AIM / MI-AIM) Design Guide & Applications Manual For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies CHOOSING APPROPRIATE VALUES FOR AIM MODULES Sample calculation: Converter output power (POM) = 100 W T4 = The low point of the rectified AC line; the point of lowest energy in C1; the point at which if the AC line fails, hold-up time is shortest, i.e., “worst case”. T5 = The time at which the converter(s) drop out of regulation. Line frequency = 60 Hz Line range = 105 – 264 Vac Efficiency = 82% T5 – T4 = Minimum hold-up time. Actual hold-up time may vary up to a maximum of T5 – T3. Desired hold-up time = 5 ms (minimum) (T3 – T1) X 2 = One line cycle. therefore: The following values are calculated in a similar manner. PIM = 100 = 122 W 0.82 T5 – T3 = 5 ms + 8.3 ms = 13.3 ms (minimum hold-up time plus half cycle) Vp = 105 X √ 2 = 148 V Module(s) Delivered Power 50 W 75 W 100 W 150 W 200 W 60 Hz 90 Vac 105 Vac 270 µF 135 µF 400 µF 200 µF 525 µF 270 µF 800 µF 400 µF 1,000 µF 540 µF 50 Hz 90 Vac 105 Vac 300 µF 150 µF 440 µF 230 µF 600 µF 300 µF 890 µF 455 µF 1,180 µF 600 µF Table 12–1 — Hold-up capacitor values for use with VI-270 / VI-J70 and the VI-250 / VI-J50 DC-DC converters. Vdo = 100 V and: C1 = C1 values as a function of line voltage, frequency and delivered power, for use with the “7” input designator DC-DC converters (AIM input of 90–264 Vac) or “5” input designator (AIM input of 90–132 Vac) DC-DC converters. 2 X 122 X 0.0133 148 2 – 100 2 C1 = 270 µF where: VP = The peak of the rectified AC line or √ 2 X Vac in. For an input range of 85 – 264 Vac, this voltage will vary from 120 – 373 V. VV = The low point of the rectified AC line under normal operating conditions. This “valley” voltage is a function of C1, PIM and line frequency. The peak-to-peak ripple across C1 is VP – VV and determines the ripple current in C1. NOTE: It is important to verify the rms ripple current in C1 with a current probe. Vdo = Voltage at which the DC-DC converter(s) begin(s) to drop out of regulation. This voltage is from the data sheet of the appropriate module, which for the VI-270 Family is 100 Vdc. Under normal operating conditions, VV must exceed Vdo. T1 = The peak of the rectified AC line or the point at which C1 is fully charged. For an input range of 85 – 264 Vac, this voltage will vary from 120 – 373 V. T2 = The low point of the rectified AC line under normal operating conditions and the point at which C1 is about to be “recharged”. This is the point of lowest energy in C1. VI-200 and VI-J00 Family Design Guide Page 35 of 98 NOTE: With “7” input DC-DC converters operated from the AIM input range of 90 – 264 Vac, 400 V capacitors must be used (Vicor Part #30240). With “5” input DC-DC converters used over the AIM input range of 90 – 132 Vac, 200 V capacitors may be used (Vicor Part #30769). Module(s) Delivered Power 50 W 75 W 100 W 150 W 200 W 60 Hz 180 Vac 210 Vac 66 µF 34 µF 100 µF 50 µF 130 µF 67 µF 200 µF 100 µF 262 µF 135 µF 50 Hz 180 Vac 210 Vac 74 µF 38 µF 110 µF 60 µF 150 µF 75 µF 220 µF 115 µF 300 µF 150 µF Table 12–1 — Hold-up capacitor values for use with VI-260 / VI-J60 DC-DC converters. C1 values as a function of line voltage, frequency and delivered power, for use with the “6” input designator DC-DC converters (AIM input of 180 – 264 Vac). NOTE: With “6” input DC-DC converters operated from the AIM input range of 180 – 264 Vac, 400 V capacitors must be used (Vicor Part #30240). Rev 3.5 Apps. Eng. 800 927.9474 vicorpower.com 800 735.6200 12. AC Input Module (AIM / MI-AIM) Design Guide & Applications Manual For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies Bussman Fuses, PC Tron L1 Universal AC In 0.47 µF NC NC +OUT GATE IN PAR GATE OUT D3 [a] C1 –OUT L2/N AIM D2 D3 D1, D2: 1N4148 C2: 470 pf / 500 V D3: 1N4006 [a] Refer to Selecting Capacitors for AIM Modules in the begining of this Section. Refer to Typical application for Vicor converter with AIM, Figure 12–5, for recommended external components. C2 D1 D3 D2 C2 D1 +IN GATE IN GATE OUT –IN +IN GATE IN GATE OUT –IN +IN GATE IN GATE OUT –IN +OUT Driver +S TRIM –S –OUT +OUT Driver +S TRIM –S –OUT +OUT Driver +S TRIM –S –OUT Y-capacitors not shown for clarity Figure 12–4 — AIM connection diagram, multiple Driver DC-DC converters 0.01 µF (Two 4,700 pF) Y-Rated Capacitors Universal AC In F1 0.01 µF Ceramic F2 L1 Z1 0.47 µF +OUT GATE IN PAR NC GATE OUT –OUT L2/N NC C1 [a] +IN GATE IN GATE OUT –IN VI-200/J00 Driver +OUT +S TRIM –S –OUT Load 0.01 µF Ceramic AIM 0.01 µF (Two 4,700 pF) Y-Rated Capacitors [a] Consult factory or refer to Selecting Capacitors for AIM Modules at the begining of this section. Z1: MOV Part #30076 Fuse 1: 6.3A/250V (IEC 5X20 mm) Buss GDB-6.3 or 7 A / 250 V (3AG 1/4" x 1 1/4") Littlefuse 314-007 Fuse 2: For VI-X7X-XX — Buss PC-Tron 2.5 A (250 V) For VI-X6X-XX — Buss PC-Tron 3 A (250 V) For VI-X5X-XX — Buss PC-Tron 5 A Figure 12–5 — Typical application for Vicor converter with AIM VI-200 and VI-J00 Family Design Guide Page 36 of 98 Rev 3.5 Apps. Eng. 800 927.9474 vicorpower.com 800 735.6200