18. AC Input Power System (FlatPAC Family) Design Guide & Applications Manual For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies OVERVIEW Vicor’s FlatPAC consists of an offline single phase AC front end and one, two or three VI-26x / VI-B6x Family DC-DC converter modules (1-up, 2-up, 3-up), combined in an integrated mechanical assembly. This assembly provides a complete, high efficiency, offline switching power supply delivering power up to 600 W. The offline front end provides rectification and filtering of the AC input, delivering a nominal unregulated 300 Vdc bus as input to the VI-26x / VI-B6x Family converter modules. The front end control circuit will automatically strap the bridge as a voltage doubler for 115 Vac operation or as a full bridge for 230 Vac operation. CIRCUIT OPERATION AC line voltage is applied via an agency-approved terminal block providing AC mains (L1, L2/N and GND). Current in the L1 lead is applied to a 15 A / 250 V fuse for the 3-up FlatPAC, a 12 A / 250 V fuse for the 2-up FlatPAC and a 8 A / 250 V fuse for the 1-up FlatPAC. This current is interrupted only in the event of a catastrophic failure of a main power component internal to the FlatPAC. The input current beyond the fuse is passed through an EMC filter designed to meet conducted noise limits of FCC Part 15 EN55022 Class B for the 2-up and 3-up versions. At start-up, AC inrush current is limited by a PTC thermistor prior to being passed to the main energy storage capacitors. This PTC thermistor serves as both an inrush current limiter on power-up and a current limiting shutdown device in the event of a line overvoltage condition. The PTC is shunted out shortly after initial power-up by a pair of inverse parallel SCRs on the 3-up FlatPAC (TRIAC for the 1-up and 2-up FlatPAC), controlled by an opto-TRIAC coupler driven by a DC bus voltage sense circuit. The main rectifiers and filter capacitors are arranged in a conventional selectable configuration and act as either a full wave bridge or voltage doubler, delivering a nominal 300 Vdc to the converter modules. At initial power-up, the front end is configured for 230 V operation and the PTC inrush limiter permits the main storage capacitors to charge up at a controlled rate toward full operating DC bus potential. If the bus voltage is below the operating threshold for the converter, the unit will autostrap for 115 V operation. The autostrapping function is performed by a control circuit and TRIAC (dual SCRs on 3-up unit) which configures the front end from a full wave bridge to a voltage doubler. Once the unit autostraps for 230 V operation, it will be necessary to recycle the AC power to allow operation at 115 V. If the unit is operating in the 115 V mode and a long duration transient is applied to the FlatPAC (>150 Vac for 50 ms), the unit will autostrap for 230 V operation. VI-200 and VI-J00 Family Design Guide Page 55 of 98 The control circuit maintains the converter GATE IN pins low, the PTC shunt inactive and the AC-OK and BUS-OK outputs in FAIL status until the DC bus potential reaches a minimum threshold at which full power and hold-up can be delivered. The GATE IN terminals of all Driver modules internal to the FlatPAC are FET-controlled by a logical replica of the BUS-OK status line, and as such will inhibit converter operation at power-up until the DC bus potential has settled to full operating level. The converters are then enabled and the PTC shunt activated. The AC-OK and BUS-OK status lines go to their respective active states almost simultaneously on initial power-up. AC-OK will de-assert prior to BUS-OK on loss of AC input, providing advance warning of impending DC failure should the AC line not return prior to the expiration of the ridethrough time (a function of both load and line voltage). The front-end output is bled down automatically after loss of AC input, as the logic circuit operating power is derived from a bleed path across the DC output bus. Wait two minutes before reapplying input after shutdown. Input voltage to the converters is made via fast-acting 3 A / 250 V Buss PC-Tron fuses in each positive input lead. The fuse will clear rapidly and protect the front-end from damage in the event of a module input short. Input overvoltage sensing and protection is performed by a voltage sensing circuit connected across the DC bus. In the event of an overvoltage condition, a SCR / PTC combination will simultaneously disable the drive for the TRIAC / SCR PTC shunt, disable the converters and apply a load across the DC bus. Normal operation resumes when the input voltage falls within the normal operating range when operated from a 230 Vac source. A Master Disable function is incorporated in the 2-up and 3-up FlatPAC (MOD DIS+, MOD DIS–). This optically isolated input will disable the output of all converters simultaneously. Applying a current to this input will disable the converters. This disable current should be limited to 30 mA maximum by an external control element. FLATPAC AC-OK AND BUS-OK STATUS OUTPUTS, MOD-DIS INPUT (2-UP AND 3-UP ONLY) The BUS-OK and AC-OK outputs provide the user with both an optically isolated status indication of the internal DC bus condition and advance warning of pending DC bus drop-out due to AC line loss. These outputs, in system applications, can provide power supply status, switch in (standby) backup sources or initiate “power-down” sequences to save volatile memory contents in the event of AC line loss. The MOD-DIS input is an optically coupled Rev 3.5 Apps. Eng. 800 927.9474 vicorpower.com 800 735.6200 18. AC Input Power System (FlatPAC Family) Design Guide & Applications Manual For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies input and allows for remote disabling of the outputs of 2-up and 3-up FlatPACs. BUS-OK. An internal replica of BUS-OK is wired to the GATE IN input of all internal Driver modules. The modules will be disabled (no DC output) during initial power-up of the FlatPAC until the internal DC input bus voltage to the DC-DC converters is sufficient to support fully-loaded operation. The BUS-OK status output reflects the status of this inhibit function. This same logic circuit will shut down the converters when the internal DC bus voltage is insufficient to support proper loaded operation. This shut down will occur during normal power down, AC line dropouts of duration exceeding the hold-up time, or internal faults causing the internal DC bus voltage at the input of the converters to collapse. AC-OK. This output is provided primarily as an advance warning of a potential DC BUS-OK shut down due to loss of AC line or an internal fault. A minimum advance warning time of 5 ms is provided at 90 Vac and full load. detect assertion of logic outputs, or a separate source of bias supply voltage (i.e., backup batteries) to provide a safe pull-up voltage source regardless of the AC line status. MOD-DIS – MOD-DIS + AC-OK – AC-OK + BUS-OK – BUS-OK + L1 AC Mains The Module Disable function will disable the output(s) of the 2-up and 3-up FlatPACs. The supply is disabled by applying current to the MOD-DIS+ / MOD-DIS– input. The minimum input current for disabling the supplies is 1 mA. The maximum allowable current is 30 mA. GND NOTE: Product is internally fused Figure 18–1 — AC mains and supervisory connections AC-OK and BUS-OK Status Outputs. Outputs low when OK. Vce sat. = < 0.4 V @ 1.5 mA. Maximum external pullup is 70 Vdc. AC-OK and BUS-OK signals are isolated and can have different reference levels. 30 mA max. ELECTRICAL CONNECTIONS FlatPAC Status output pairs AC-OK+, AC-OK– and BUS-OK+, BUS-OK– are the collectors (+) and emitters (–) of NPN optoisolator output transistors (one optoisolator per status signal). The collector terminals AC-OK+ and BUS-OK+ of the optocouplers, in a typical application, can be connected via current limiting resistors to a source no greater than 70 Vdc. These resistors should limit the maximum current to the optocoupler output transistors to 1.5 mA. The emitter terminals AC-OK– and BUS-OK– are connected to the return of the external source. The status OK condition will set the optocoupler output transistors in saturation and are capable of sinking up to 1.5 mA with a Vce saturation voltage of 0.4 V. Users should be cautioned that although the output of the FlatPAC can be used as the pull-up source, shortly after BUS-OK changes from OK (saturated) to NOT OK (high Z), the pull-up voltage will be shut down. It is thus advisable to provide a capacitive reservoir, if the pull-up source is one of the FlatPAC’s outputs, in order to maintain the pull-up potential after loss of DC current output. Use edge sensing logic to Page 56 of 98 1-Up L2/N Earth Ground 2-Up and 3-Up MOD-DIS Input. Apply a current of 1 – 30 mA to disable output. Forward voltage drop of internal opto diode is 1.65 V max. at 30 mA max. MOD-DIS+, MOD-DIS– VI-200 and VI-J00 Family Design Guide Internal Supervisory Circuits (Optocouplers) Disable + V + MOD-DIS + V 1.5 mA max. r + AC-OK – 1.5 mA max. + V – r + BUS-OK – Figure 18–2 — External supervisory functions (2-up and 3-up models only) Rev 3.5 Apps. Eng. 800 927.9474 vicorpower.com 800 735.6200 18. AC Input Power System (FlatPAC Family) Design Guide & Applications Manual For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies Input Voltage Connections. Connect the line voltage to L1 (hot) and L2N (neutral). For 1-up FlatPAC models (max. output 200 W), use #16 AWG input wire; for 2-up and 3-up models (max. output 400 W and 600 W), use #14 AWG input wire. Recommended connector screw torque is 5 to 7 in-lbs (0.5 to 0.8 N-m). Recommended strip length is 8 mm. Use your FlatPAC model only with the corresponding input voltages and frequencies shown in the table below. VLINE > 90 (180)Vac AC Line AC Line Interrupted AC-OK BUS-OK T0 T1 T2 T4 T3 Conditions: Full Load 90 (180)Vac, AC Line Time Interval Min Typ Max Units Notes T1 – T0 T3 – T2 0 0 0.1 – 1.0 – ms ms Ride-through time T4 – T2 T4 – T3 5 5 – – – – ms ms Hold-up time AC fail warning time Figure 18–3 — Timing diagram – status signals (2-up and 3-up models only) +OUT +SENSE TRIM –SENSE R1 10K –OUT R2 + VOUT R1 (KΩ) R2 (KΩ) 15 V 24 V 28 V 48 V 0.953 15.8 90 90 22.1 41.2 90 90 48.7 90 VOUT RTN Trim Range 90.9 +10%, –10% 90 +10%, –10% Figure 18–4 — Output SENSE and TRIM (all models with VI-200s) +OUT VTRIM ITRIM IMON –OUT Battery Charger External Control Functions Programmable Current or Voltage Source + 12 – 48 V Battery – +OUT VTRIM ITRIM IMON –OUT External Control Functions + – Load Figure 18–5 — Typical applications (models with BatMods only) Fusing. The FlatPAC’s internal fuses are not user-replaceable. Please return the unit to vendor if servicing is necessary. Grounding. To satisfy IEC950 Class I grounding requirements, connect a ground lead to the terminal marked (GND). For 1-up FlatPAC models (max. output 200 W), use 1.5 mm 2 / #16 AWG wire; for 2-up and 3-up models (max. output 400 W and 600 W), use 2.5 mm 2 / #14 AWG wire. VI-200 and VI-J00 Family Design Guide Page 57 of 98 90 – 132 Vac 180 – 264 Vac VI-xU-Cx VI-xU-Ix 47 – 63 Hz 47 – 440 Hz 47 – 63 Hz 47 – 440 Hz Output Wire Gauge. Use the output wire gauge that corresponds to the output current of your Autoranging FlatPAC unit, below: Do not loosen bottom nut. Long cable runs, or wires in large bundles will require heavier cable to avoid excessive voltage drops or overheating. Resister Values for Trimming Standard Output Voltages 12 V Model C-Grade I-Grade 100 A – 160 A: #2 AWG 30 A –50 A: #8 AWG 10 A –15 A: #14 AWG 75 A –100 A: #4 AWG 20 A –30 A: #10 AWG 6 A – 10 A: #16 AWG 50 A – 75 A: #6 AWG 15 A –20 A:#12 AWG 0 A – 6 A: #18 AWG NOTE: +SENSE and –SENSE must be connected locally or remotely (shown). Nom. Output 5V Voltage Product Grade Output Voltage Trimming. Do not trim the outputs higher than 110% of their nominal output voltage. When an output is trimmed up, do not exceed its maximum rated output power. (refer to Section 5) Operating Temperature. Do not allow the FlatPAC to exceed its maximum operating temperature, which is reached when the heat sink is 85°C. (Full power can be delivered up to this temperature.) Heat sink temperature is a function of the output power and voltage of the supply, ambient temperature, and airflow across the heat sink. Always use worst-case conditions when calculating operating temperature. NOTE 1: To ensure proper heat transfer from the internal module(s) to the heat sink, the mounting holes through the heat sink (two, three, and four holes on 1-up, 2-up, and 3-up models, respectively) must contain torqued screws at all times during operation, whether or not the unit is mounted. If the unit is operated unmounted, insert a #6 or M3.5 panhead screw through each hole from below and secure with a nut on top, torqued to 6 in-lbs (0.7 N-m). NOTE 2: All FlatPAC models are available with a conduction cooled flat plate instead of the top heat sink. Go to vicorpower.com for outline drawings. Input / Output Retrofit Connections. A hardware kit, available from Vicor, allows the input and output supervisory terminals to be connected in the same manner as for the earlier style FlatPAC (2-up model only). The retrofit output terminals are sized to accept AMP Faston® insulated receptacle #2-520184-2. Rev 3.5 Apps. Eng. 800 927.9474 vicorpower.com 800 735.6200