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Design of Capacitor Charging Power Supply

Swaminath Katte
Prodigy 50 points
Other Parts Discussed in Thread: UCC28950, UCC2895, UC2825A, UC2856, LM25037, SG3524, UCC28180

Hi,

I need support for design of capacitor bank charging power supply. I use this stored energy in a capacitor to drive an actuator for closing and breaking operation of circuit breaker.

Actuator Specifications-

1 Rated Voltage- 135V

2 Rated Current- 34A

3 On Duration- 60msec

4. Energy required - 367 Joules

Capacitor Bank Specification

Capacitance- 50mF

Rated Voltage- 450V

Charge time 0.08sec

Repetition Rate- 10Hz

Power Supply Specifications


Input Voltage- 220VDC

Charging Rate = 3672 Joules/sec

Peak Power = 5100W

Average power = 4080W

Output Charging Current - 68A

Kindly suggest power supply topology and controller to design capacitor charging supply.

Thanks,

Swaminath

  • 0
    Prodigy 5 points

    Hello Swaminath,

    Interesting application 

    At this power level you must start with a PFC power factor correction creating a ~400V DC buss.
    Follow it with an isolated converter that can allow it's Vout to vary by duty cycle control.

    PFC:
    There are several examples in our TI DESIGNS power section.
    TI Home > TI Designs: Reference Designs Library > 

    Here is a good example:
    5KW Interleaved CCM Power Factor Correction Converter
        UCC27322
        UCC28070
        UCC28610

    However, for the DCDC stage, whose Vout must vary based on the charge of the capacitors, TI does not have an example.
    At this power level you would be looking at a forward converter:
    1. Phase Shifted Full Bridge
        but with high Vout you may find difficulty in the transformer design and resonant calculations.
        UCC2895, UCC28950

    2. Hard Switched Full Bridge
        UC2825A, LM25037, UC2856, there are many full bridge controllers


    Another possibility may be using a non-isolated Buck.
    Isolation from the AC lines may not be needed for your design, that is up to you.
    A Half Bridge is a synchronous buck in one direction, synchronous boost in the other.
    Take a look at the UCC25120A 4A/6A, 5.7 kVrms Isolated Dual Channel Gate Driver

       

    In the picture below the controller to produce PWM-A PWM-B would be the UC2825A, LM25037, UC2856, dual alternating PWM controllers.
    The dual channel driver then controls the upper and lower mosfets to perform a PWM synchronous buck topology.

    I wish you success with your design, Swaminath. 

  • 0 in reply to Ed Walker
    Prodigy 50 points

    Hello Sir,

    Thank you for your valuable design guideline and wishes.

    I do have experience in only low power SMPS design <10W using flyback topology.

    The Interleaved CMM PFC converter is new to me and do not have experience in high power design. So I need theoretical explanation and design steps for the same.

    Kindly suggest some study materials like  application/ design note/Practical design books for interleaved CCM PFC converter.

    And few more point I would like to add

    1. If I reduce required peak and average power (less than to 2KW)  by increasing charging time and reducing charge rate, are there any other power supply typologies to charge a capacitor bank. (Eg. like inverter using SG3524).

    2.When capacitors get fully charged there will not be output current(no load Condition) how these power supply regulate the output voltage for no load to full load variation.

    Thank You,

    Swaminath

  • 0 in reply to Swaminath Katte
    Prodigy 5 points
    Hello Swaminath,

    Charging capacitor is like charging a battery.
    Really a battery is a large capacitor.

    Charging is 2 phases;
    1. Constant current, the power supply regulates current into the capacitor when Vcap<Vmax.
    2. Constant voltage, once Vcap=Vmax then the voltage is regulated, holding Vcap at Vmax.

    When the load takes some energy from the cap, its voltage will drop.
    Phase 1 of charging is initiated.
    If your charging current is 100mA and the load wants 1Amp then the capacitors provide 900mA during a load transient.

    Here is a useful tool for exploring topologies.
    www.ti.com/.../powerstage-designer


    The SG3524 is an old PWM that could be used to control various topologies with current and voltage loops.
    There are many newer PWM's that can perform better.

    For CCM PFC, a devices product folder would have much information.
    UCC28180 is a good example.
    www.ti.com/.../UCC28180

    Other CCM PFC controllers may have different application material but still relevant.
    You should explore several of our CCM PFC devices.
    www.ti.com/.../power-factor-correction-overview.page