TIDUBE1D January   2016  – August 2024

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Highlighted Products and Key Advantages
      1. 2.2.1 UCC28180 – PFC Controller
      2. 2.2.2 UCC27524 – Dual Low-Side Gate Driver
      3. 2.2.3 UCC28881 – 700-V Off-Line Converter
    3. 2.3 System Design Theory
      1. 2.3.1 Selecting Switching Frequency
      2. 2.3.2 Calculating Output Capacitance
      3. 2.3.3 Calculating PFC Choke Inductor
      4. 2.3.4 Selecting Switching Element
      5. 2.3.5 Boost Follower Control Circuit
      6. 2.3.6 Bias Power
      7. 2.3.7 On-Off Switch
      8. 2.3.8 Thermal Design
  9. 3Hardware, Testing Requirements, and Test Results
    1. 3.1 Required Hardware
      1. 3.1.1 Test Conditions
      2. 3.1.2 Recommended Equipment
      3. 3.1.3 Procedure
    2. 3.2 Test Results
      1. 3.2.1 Performance Data
        1. 3.2.1.1 Efficiency and iTHD
        2. 3.2.1.2 Standby Power and Output Voltage
      2. 3.2.2 Performance Curves
        1. 3.2.2.1 Efficiency Curve
        2. 3.2.2.2 Voltage Follower Performance
      3. 3.2.3 Functional Waveforms
        1. 3.2.3.1 Power On Sequence
        2. 3.2.3.2 Inrush Current Protection
        3. 3.2.3.3 Switching Node
        4. 3.2.3.4 Waveform Under 3.5kW, 230VAC
      4. 3.2.4 Thermal Measurements
  10. 4Design Files
    1. 4.1 Schematics
    2. 4.2 Bill of Materials
  11. 5Documentation Support
  12. 6Trademarks
  13. 7About the Author
  14. 8Revision History

1 System Description

Major appliance equipment such as air conditioners, refrigerators, and washers use three-phase, pulse-width modulated BLDC or PMSM drives. These motor drives typically have fractional or low horsepower ratings ranging from 0.25HP (186W) to 5HP (3.75kW). An electronic drive is required to control the stator currents in a BLDC or PMSM motor. A typical electronic drive consists of:

  • Power stage with a three-phase inverter with the required power capability
  • Microcontroller unit (MCU) to implement the motor control algorithm
  • Motor voltage and current sensing for closed-loop speed or torque control
  • Gate driver for driving the three-phase inverter
  • Power supply to power up the gate driver and MCU

These drives require a front-end power PFC regulator to shape the input current of the power supply and to meet the standards for power factor and current THD, such as IEC61000-2-3. A PFC circuit shapes the input current of the power supply to be in phase with the mains voltage and helps to maximize the real power drawn from the mains. The front-end PFC also offers several benefits:

  • Reduces RMS input current
    For instance, a power circuit with a 230-V/5-A rating is limited to about 575W of available power with a power factor (PF) of 0.5. Increasing the PF to 0.99 almost doubles the deliverable power to 1138 W, allowing the operation of higher power loads.
  • Facilitates power supply hold-up
    The active PFC circuit maintains a fixed, intermediate DC bus voltage that is independent of the input voltage so that the energy stored in the system does not decrease as the input voltage decreases. This maintenance allows the use of smaller, cost effective bulk capacitors.
  • Improves efficiency of downstream converters
    The PFC reduces the dynamic voltage range applied to the downstream inverters and converters. As a result, the voltage ratings of rectifiers can be reduced, resulting in lower forward drops. The operating duty cycle can also be increased, resulting in lower current in the switches.

This reference design is a boost PF regulator implemented using the UCC28180 device as a PFC controller for use in all appliances that demand a PF correction of up to 3.5kW. The design provides a ready platform of an active front-end to operate downstream inverters or DC/DC converters operating on a hi-line AC voltage range from 190-V to 270-V AC.

This design demonstrates a high power density PF stage in a small form factor (200 × 145 mm) that operates from 190-V to 270-V AC and delivers up to 3.5 kW of continuous power output to drive inverters or converters at more than a 98% efficiency rate without an SiC device. This reference design also provides flexibility for the boost follower configuration, in which the boost voltage can be varied with AC input voltage, but only can work on the boosted voltage when it is above the peak input voltage. The boost follower configuration helps reduce switching losses in the PFC regulator and the downstream inverter or converter. .

Above all, this reference design meets the key challenges of appliances to provide safe and reliable power with all protections built in while delivering a high performance with low power consumption and a very competitive bill-of material (BOM) cost.