|作者：61ic 文章来源：61ic 点击数： 更新时间：2015-3-18|
The UCC2871x family of flyback power supply controllers provides isolated-output Constant-Voltage (CV) and Constant-Current (CC) output regulation without the use of an optical coupler. The devices process information from the primary power switch and an auxiliary flyback winding for precise control of output voltage and current.
An internal 700-V start-up switch, dynamically-controlled operating states and a tailored modulation profile support ultra-low standby power without sacrificing start-up time or output transient response.
Control algorithms in the UCC28710 family allow operating efficiencies to meet or exceed applicable standards. The output drive interfaces to a MOSFET power switch. Discontinuous conduction mode (DCM) with valley switching reduces switching losses. Modulation of switching frequency and primary current peak amplitude (FM and AM) keeps the conversion efficiency high across the entire load and line ranges.
The controllers have a maximum switching frequency of 100 kHz and always maintain control of the peak-primary current in the transformer. Protection features help keep primary and secondary component stresses in check. The UCC28710, UCC28714 and UCC28715 allow the cable compensation to be programmed. The UCC28711, UCC28712 and UCC28713 devices allow remote temperature sensing using a negative temperature coefficient (NTC) resistor while providing fixed cable-compensation levels.
< 10-mW No-Load Power
Primary-Side Regulation (PSR) Eliminates Opto- Coupler
±5% Voltage and Current Regulation Across Line and Load
700-V Start-Up Switch
100-kHz Maximum Switching Frequency Enables High-Power Density Charger Designs
Quasi-Resonant Valley-Switching Operation for Highest Overall Efficiency
Frequency Jitter to Ease EMI Compliance
Wide VDD Range Allows Small Bias Capacitor
Clamped Gate-Drive Output for MOSFET
Overvoltage, Low-Line, and Overcurrent Protection Functions
Programmable Cable Compensation (UCC28710, UCC28714 and UCC28715)
NTC Resistor Interface (UCC28711, UCC28712 and UCC28713) with Fixed Cable Compensation Options
• USB-Compliant Adapters and Chargers for Consumer Electronics
– Smart Phones
– Tablet Computers .
• Standby Supply for TV and Desktop
• White Goods
Variable-speed drive (VSD) consists of a power section, controller, user IO, display, and communicationblocks. The power section contains a rectifier, a dc link, inrush current limiting, and an insulated-gatebipolar transistor (IGBT) based inverter. VSD can be based on single or dual controller architecture. Whenusing single controller architecture, the same processor controls generation of pulse-width modulation(PWM), motion control, IO interface, and communication. When dual controller architecture is used, PWMand motion control have a dedicated controller and the other controller is used for application control. Themain power supply, either powered directly from ac mains or from dc links, is used to generate multiplevoltage rails. Multiple voltage rails are required for the operation of all the control electronics in the drive.
The traditional way of implementing the main power supply is to use flyback converters with PWMcontroller ICs, such as UCC3842, UCC3843, or UCC3844. Due to a regenerative action from the motor,the voltage rating of the MOSFET used in the flyback converter has to be > 1.5 kV, depending upon thevoltage rating of the drive. Opto-couplers are used for isolated feedback and to regulate the outputvoltage. In case of failure of components used in the feedback path, the output may reach a dangerouslyhigh level, which would damage all the electronic components. Use of controllers like the UCC3842 devicepresents other challenges, for example, limiting the power during short circuit across wide input-voltagerange and power dissipation in the resistors used in startup circuit.
The primary objective of this reference design is to create a power supply with reduced BOM cost and areusable design for drives operating at both 400-V and 690-V inputs. Other benefits include:
• Topology to replace single high-voltage FET with two low-cost FETs
• Constant uniform power limit throughout the input range
• Reduced BOM cost by using UCC28711 through primary side regulation, thus eliminating isolatedsecondary feedback
• Protection against component failure in the feedback path
This reference design provides isolated +24V (45W), ±16 V (4.5W), and +6V (0.5W) outputs to power the control electronics in variable speed drives. The power supply can be either powered directly from 3-phase AC mains (380Vac to 690Vac) or can be powered from the DC-link voltage (400Vdc to 1200Vdc). This design uses a quasi-resonant flyback topology and is rated for 50-Watt total output power. The line and load regulation of the power supply is designed to be within 5% using primary-side regulation (eliminating costly feedback components). The power supply is designed to meet the clearance, creepage, and isolation test voltages as per IEC61800-5 requirements.
Versatile input: can be either 400V-1200V DC or 380V-690V AC
<5% line and load regulation
Protection against input UV/OV, output overload, short-circuit and loss of feedback
Low-cost solution by implementing primary-side regulation (eliminates feedback loop) and use of 1000V rated MOSFETSs
Quasi-resonant mode controller improves EMI performance
Designed to comply to IEC 61800-5
• Variable Speed ac and dc Drives
• Industrial Inverters
• Solar Inverters
• UPS Systems
• Servo Drives
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