High Frequency DC/DC Converter Design Example

To help you kick start your development, Altera provides a design example for a hybrid EV DC-DC converter (variable voltage control or VVC) digital controller with predefined platform targeting a MAX® 10 FPGA. The architecture and theory are described in the white paper FPGA-Based Control for Electric Vehicle and Hybrid Electric Vehicle Power Electronics.

The design example uses the DSP Builder Advanced Blockset to simulate and synthesize VHDL control. The VHDL is then targeted to a BeMicro MAX 10 Evaluation kit (available from Arrow Electronics).

Download Design Example from Altera Design Store >>

Model-Based Design Flow

  1. Start with your own algorthm.
  2. Implement the algorithm as a Matlab/Simulink model.
  3. Simulate your model.
  4. Incorporate the model in DSP Builder using the Advanced Blockset library.
  5. Compile the design and implement it on your target FPGA (DSP Builder auto-generates the VHDL code).
  6. Verify that the result matches your simulation.

 

Altera’s DSP Builder tool provides Mathworks Simulink design blocks and the ability to auto-generate HDL code. It allows the same model used to simulate the system to be directly implemented into the FPGA. It also enables the designer to leverage a rich library of power electronics components when constructing the test bench or system simulation model.

For More Efficient Power Conversion

Faster switching allows you to reduce inductance and capacitance values to achieve equivalent voltage and current ripple. However, faster switching increases transistor switching losses and requires higher bandwidth, which are both challenges for an MCU-based system using IGBT.

FPGA-based high-frequency valuable voltage DC/DC converters (VVC) allow the use of smaller, lower-cost reactive components, and increasingly available high-speed switching silicon carbide (SiC) MOSFETs.

FPGAs offer:

  • Cost effectiveness: FPGAs enable the use of smaller, lower-cost reactive components and  high-speed switching silicon carbide (SiC) MOSFETs.
  • Processing speed: Algorithms can be accelerated and parallelized as necessary in FPGA hardware.
  • Scalability: Ehanced technologies, such as multi-level converters, can be implemented.
  • Functional safety: Safety logic (a Clock checker, for instance) can be implemented to monitor MCU status as a fail-safe device.

A 5X increase in switching frequency reduces inductance and capacitance values for the same ripple current and voltage. These reductions reduce size and cost.

This increased bandwidth is a challenge for MCU-based solutions where multiple functions are implemented with one processor. FPGA control can easily provide the bandwidth, even if multiple control functions are implemented on one device. 

FPGA System Benefits: System Size, Weight, and Cost Reduction

 

  • Smaller passives and faster response
  • Fewer components
  • Savings in cost, weight, and space
  • Future proof (allows system upgrades)

Comparison of VVC 10 kHz and 50 kHz Designs

Item

Current system

Next generation

Size reduction

Potential cost reduction

Inductor (L)

200 uH

40 uH

5X

$200 to $100

Capacitor (Chv)

2000 uF

400 uF

5X

$300 to $100

Capacitor (Clv)

400 uF

80 uF

5X

$100 to $50

IGBT Losses

500 W

1100 W

-

-

SiC MOSFET Losses

150 W

250 W

2X

Higher cost but declining