Benchmark Report on Control Boards for Toyota’s Prius (DAA-ZVW51) and Power Control Unit (PCU)
2017/04/17
Summary
 |
| Fig.1 Product view Source: Toyota Motor Corp. |
 |
| Fig.2 PCU topological view Source: Toyota Motor Corp. |
The 4th-generation Prius launched in December 2015 is equipped with an engine that has a maximum thermal efficiency of 40%. In addition, the system consisting of the motor, transaxle, power control unit, and drive battery has been designed both to reduce size and weight, and lower loss by roughly 20%. The Power Control Unit (PCU), which will be the focus of analysis in this report, is installed adjacent to the engine, and its general functions are as follows: (1) 2-way DC-DC converter, (2) regenerating inverter, and (3) motor driver inverter. The PCU achieves improve loss reduction for the heat radiating system of IGBT-equipped power cards that are conventionally adopted, and also reduces size roughly 30% by unifying the high-side and low-side IGBTs into one card. A control board is positioned on the very top of the PCU, and it is this board as well as the power card that achieve the functionality noted above.
The gate driver attached to the power card has functions of operating the gate to achieve an appropriate slew rate, as well as detecting the temperature and excess current. Moreover, the controller comprises a custom ASIC that integrates a number of features into 1 chip that include the following: isolated power supply-use oscillation circuit; internal power supply circuit; battery voltage / boosted voltage detection circuit; 2 MCU that perform vector control calculations for the 2 motors and generator; and power source-use error amplifier + CAN + ADC + resolver interface. The control board has 6 layers and through-holes.
The gate driver connected to the power card is isolated from lower voltage circuits such as the MCU by means of the transformer and photo-coupler, and the circuit patterns are also isolated with each other physically (patters are isolated for individual gate drivers). This design seems to takes breakdown voltage and the reduction of electric field influence into account.
 |
 |
| Fig.4 X-ray photo of the board (side view) | Fig.3 Board (bottom view) |
 |
Free membership registration allows you to read the rest of the article for a limited time.