Considering Modular Design Approach at the system design stage yields large product families released to market in shorter time.
Mechanical design - a modular concept, where all the circuitry presented in the Functional Diagram are functionally grouped into independent plug-in modules via baseplate is in existence for long time and practiced successfully by many power supply manufacturers. The idea of modularity is to provide flexible architecture, standardization and adaptation, increase in reliability (MTBF), shorten meantime to repair (MTTR), and quick replacement in the field. The availability of power supply modules, e.g.:
- Battery Back-up
- Forced Parallel Sharing,
enables the system designer to use a building block approach to satisfy his specific requirements.
Modular power supply configurations are designed for maximum producibility using the same modules already designed and improving the plug-in techniques to the maximum extent practical. Modules are plug-in and removable without disturbing adjacent modules by using its plug-in connector arrangement that plug into wiring harness or mother-board of mating connector. Modules are fabricated and operated independently, and are tested prior to final installation by utilizing its plug-in connector arrangement for additional performance monitor and fault isolation. Final test is then accomplished, which includes pre-acceptance testing in accordance with an approved test procedure. Module replacement will not require subsequent scheduled or unscheduled adjustment, opening the possibilities of Field- Configurable and Field Depot Repair.Introducing: 85-100Watt Multi-Output W/PFC Module (Standard Option) Series, SMPS, Single Board/ Single Transformer Design, encompassing more than 200 Standard Models, grouped as follows:
Note: Dual Safety Qualifications: EN60950 (ITE: Information Technology Equipment) and EN60601 (Medical) will again double the standard models available.
100W Converter Family is a high efficiency (>90%) fixed frequency (100KHz typ.) switching MosFet Technology, converting one phase input power: 90-264VAC, 50-60Hz to various standard SELV output DC voltages: single, dual or triple. The Main Converter Topology is Flyback Continuous-Mode, ZV (zero-voltage), Quasi-Resonant ,Parallel Multi-Resonant, Phase- Shifted Lead/Lag, Zero-Turn on losses: D-S capacitance fully discharged prior to the turn-on sequence, Snubberless Inverter.
In addition the Power Supply produces Built-In-Test Hardware to discover fail conditions: OV/OC/Short Circuit /OT; will shutdown with automatic recovery, activating BIT signal, optional; Visual Output DC Present will turn-off. Over-Voltage protection, has a second alternate: Shutdown and latched reset by cycling input power.
Input fusing, both line and neutral for medical applications, has time delay characteristics to compensate for inrush current during turn-on, and disconnect power supply from power system in case of failure. FMEA, Failure Mode and Effect Analysis performed at functional module level identified as maximum Severity Class 7: complete shutdown with BIT Detection.
Internal Bias Regeneration is designed to operate through power interruptions, according to Voltage Sag Immunity and Voltage Fluctuations Standards. The internal bias housekeeping isolates the control (sensitive) circuits from the hostile power line, improves human safety (Manprint) and allows control of the power up/power down cycles. The bias is synchronized to the local storage through the regeneration circuit keeping the control circuitry operating during input power interruption.
The Input Line Conditioner with common mode and differential low-pass cascaded L-C EMI filters and high-frequency noise attenuators meets EMI Standards: Emissions: EN55022, EN55011 class B, FCC Part 15 class B and Immunity: EN550082-1. With addition of PFC Module, Passive or Active, Harmonics Emissions Standard EN61000-3-2 is met. Unit is eligible for CE Mark, when Safety Certifications, dual for 100W family: ITE: EN60950 and Medical: EN60601 are completed.
To minimize leakage current, <100uA, to meet Medical Leakage for Class B/BF Equipment, requires reduction of line-to-ground EMI filters compensated for a class B filter by EMI noise generators reductions such as: copper shielding Pri-Sec Transformer, PCB careful wiring layout which carry switching waveforms, soft recovery diodes, ground plane. And all these electrical/mechanical design techniques merged into creapage-clearance requirement of the medical standards.
Other Input Performance Characteristics
Inrush Limiting in series with the input storage capacitance will prevent damaging the input circuitry during turn-on. Inrush current is generated in the input line by the power supply which acts as a low impedance for few cycles, meantime, the input voltage capacitance builds up its voltage and inrush current is terminated. The peak current is controlled by the thermistor cold start resistance, or for militarized units by the inrush resistor and energy dissipated optimized by the triac delay circuit.
Input protection against line surges/spikes above 400V superimposed on the power line voltage, 50us max. pulse width, are insured by differential transient suppressors.
Turn-on Delay; Turn-on/off overshoots are controllable by the active soft-start circuitry; controls the charging time of the soft-start capacitor and also provides a low impedance path for power down command. Peak current limit circuit will protect the power devices, providing instantaneous limiting of drain current when the control logic glitches due to random noise or other abnormal circumstances.
Hold-up time is provided by the DC Filter/ Local Storage Capacitance >20ms hold-up time for input power interruptions/transients larger than one cycle and supplies high frequency current to the main inverter/minimizes primary current stresses. Bleeder networks discharge the storage capacitors to 30V within two seconds after power removal (Manprint-safety).
Output Performance Characteristics:
Output Regulation within ±1% is achieved through Remote Sensing terminated at output cord connector level to compensate for max. 0.5V voltage drop in the output cable; optionally output pins may be dedicated to +sense, -sense functions. For 3.3V output and lower output voltages remote sense is mandatory. Custom units can provide as low as 1.8V output at within 1% ripple by using cascaded output filtering for ripple rejection in vicinity of linear performance.
For multi-output models, weighted voltage feedback combined with feed-forward characteristics of flyback topology provides 5% regulation for second output and 10% regulation for third output.
Current mode inner loop allows bandwidth expansion and dynamic response within regulation band.
Efficiency>90% . Phase Shift Lead/Lag and drive circuitry is an added function to the parallel quasi-resonant, snubberless converter. By implementing drive pulse phase-shifting in flyback topology, MosFet D-S capacitance is fully discharged prior to the turn-on sequence, achieving zero-voltage/zero-loss turn on characteristic, with an increase in overall efficiency above 90%.