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25 kW FM3 Three-Phase Inverter

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Ujala_MG
Ujala_MG Contributor Level 2
in Module Products

Hi,

I have already purchased two Wolfspeed inverters (25kW), but I have a concern about their auxiliary DC supply.
Are you recommending a specific DC supply source for the auxiliary DC power? Could you please provide the specifications for the auxiliary supply? Additionally, do we need to establish a common ground between the negative terminal of the DC auxiliary power and the negative terminal of the inverter DC link?

Thank you!

Comments

  • Forum_Moderator
    Forum_Moderator Wolfspeed Employee - Contributor Level 5
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    Thank you for your post, it has been approved and we will respond as soon as possible.

  • ChrisN
    ChrisN Wolfspeed Employee - Contributor Level 3
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    Hello Ujala_MG,

    We use the Phihong USA PSAA30R-120 for internal testing and recommend it. You will also need to purchase the associated AC clip for it based on your region of the world. In our USA labs, we use Phihong USA RPA-AB01B-H. You do not need to establish a common ground.

    Thanks,

    Chris N.

  • Ujala_MG
    Ujala_MG Contributor Level 2
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    Thank you for the details.

    Is Galvanic isolation already built in to the Wolfspeed inverter 12V supply?

  • ChrisN
    ChrisN Wolfspeed Employee - Contributor Level 3
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    Hello Ujala_MG,

    The CAN communication and TI controlCARD USB have built-in isolation, so all communications to the design are isolated. Furthermore, we recommend communicating with the board through an isolated CAN adapter such as the PEAK System IPEH-004061 for redundant isolation.

    Since the gate drivers have an isolation barrier from the control circuitry, there is no direct link between the high voltage power circuitry and the low power control circuitry. There is no need for specific isolation in the 12V supply, though you can use a galvanically isolated supply if you wish.

    Thanks,

    Chris N.

  • Ujala_MG
    Ujala_MG Contributor Level 2
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    Thank you!

    I have a concern on the Wolfspeed inverter board's resolver excitation signal generation too.

    Can I know if it is only required to generate a PWM signal for PWM8B? Does the wolfspeed board on-board hardware generate the corresponding filtered and amplified sine waveform for the excitation signal? If that is so, can you please let me know the amplification of the signal?

  • ChrisN
    ChrisN Wolfspeed Employee - Contributor Level 3
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    Hello Ujala_MG,

    The board includes sine wave filtering and amplification. The default gain is 3.92 (470k/120k). I attached an LTspice simulation showing the excitation circuit on the board. The gain can be adjusted (in hardware and in the simulation) by modifying the R_F and R_IN parameters.

    Resolver Excitation.zip

    Thanks,

    Chris N.

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