transphorm TDINV3000W050B 3000W Inverter Evaluation Board User Guide
- October 29, 2023
- transphorm
Table of Contents
TDINV3000W050B 3000W Inverter Evaluation Board
User Guide
Introduction
The TDINV3000W050B 3000W inverter kit provides an easy way to evaluate the performance advantages of GaN power FETs in various inverter applications, such as solar and uninterruptible power supplies (UPS). The kit provides the main features of a single-phase inverter in a proven, functional configuration, operating at or above 50 kHz. At the core of the inverter are four TP65H050G4WS 50mΩ GaN FETs configured as a full bridge. These are tightly coupled to gate-drive circuits on a board which also includes flexible microcontroller options and convenient communication connection to a PC. The switch-mode power signals are filtered to provide a pure sinusoidal output. For more information and the complete design files, please visit https://www.transphormusa.com
The TDINV3000W050B is for evaluation purposes only.
Warning
This evaluation board is intended to demonstrate GaN FET technology and is for
demonstration purposes only and no guarantees are made for standards
compliance.
There are areas of this evaluation board that have exposed access to hazardous
high voltage levels. Exercise caution to avoid contact with those voltages.
Also note that the evaluation board may retain high voltage temporarily after
input power has been removed. Exercise caution when handling.
When testing converters on an evaluation board, ensure adequate cooling. Apply
cooling air with a fan blowing across the converter or across a heatsink
attached to the converter. Monitor the converter temperature to ensure it
does not exceed the maximum rated per the datasheet specification.
The control portion of the circuit is designed around the DSP Modules from Microchip. The source code is available along with related support information directly from Microchip. In addition to this general resource, Transphorm provides original firmware which comes loaded in flash on the microcontroller. The source code, configured as a complete project, is available at https://www.transphormusa.com. This project is a convenient starting point for further developments. The microcontroller itself resides on a small, removable control card, supplied by Microchip, so that different DSP Modules can be used. The schematic for the TDINV3000W050B circuit board is provided at the end of this user guide document, as well in the design files.
The TDINV3000W050B-KIT includes:
- TDINV3000W050B single-phase inverter assembly
- Microchip DSPIC33 Plug In Module (PIM)
- 12V power supply with U.S. adaptor
Complete design files, firmware files and support documentation can be found
online at https://www.transphormusa.com.
TDINV3000W050B input/output specifications
- High-voltage input: 400VDC max
- Auxiliary supply (J1): 12VCC
- Input Voltage: 0VDC – 400VDC
- Output Voltage: VDC / √2VRMS at 50/60Hz1, up to 3000W
- PWM frequency: 50kHz
- Power dissipation in the GaN FET is limited by the maximum junction temperature. Refer to the TP65H050G4WS datasheet
The output frequency may be changed in the software; as delivered it is 60Hz
Circuit description
Refer to Figure 2 for a block diagram of the inverter circuit. A detailed
schematic is available in the design files.
The TDINV3000W050B inverter is a simple full-bridge inverter. Two GaN half-
bridges are driven with pulse-width modulated (PWM) command signals to create
the sinusoidal varying output. The output filter largely removes the
switching frequency, leaving the 50/60Hz fundamental sinusoid. The high-
frequency (50 kHz+) PWM signals are generated by the Microchip
microcontroller and connected directly to high speed, high voltage gate
drivers. A connection for external communication to the microcontroller is
provided by an isolated USB interface. Except for the high-voltage supply for
the power stage, all required voltages for the control circuitry are derived
from one 12V input. 
The inverter takes advantage of diode-free operation, in which the
freewheeling current is carried by the GaN FETs themselves due to their bi-
directional capability, without the need of additional freewheeling diodes.
For minimum conduction loss, the gates of the FETs are enhanced while they
carry the freewheeling current. The high and low- side VGS waveforms are
therefore pairs of non-overlapping pulses, as illustrated in Figure 3 below.
Gate drivers
High-voltage integrated drivers supply the gate-drive signals for the high and
low-side GaN FETs. These are 2500V isolation drivers (Silicon Labs Si82xx
family), specifically chosen for high-speed operation without automatic dead
time insertion. The dead time between turn-off of one GaN FET in a half-bridge
and turn-on of its mate is set in the firmware.
Dead time control
The required form of the gate-drive signals is shown in Figure 3. The times
marked A are the dead times when neither transistor is driven on. The dead
time must be greater than zero to avoid shoot-through currents. The Si82xx
gate drive chip ensures a minimum dead time based on the value of resistor R4
and R5, connected to the AC input. The dead time in ns is equal to the
resistance in kΩ x 1, so the default value of 150k corresponds to 150ns. This
will add to any dead time already present in the input signals. The on-board
pulse generator circuit; for example, creates dead times of about 100ns (see
Figure 6). The resulting dead time at the gate pins of Q1 and Q2 is about
100ns. Either shorting or removing R4, R5 will reduce the dead time to 60ns.
Output filter
A simple filter on the output (L1, L2) attenuates the switching frequency,
producing a clean sinusoidal waveform for output connections in terminals J4
and J5. The filter inductors and capacitors used on the demo board were
chosen to provide the optional combination of benefits: low loss, good
attenuation of the switching frequency, and small size. Consult the schematic
and/or bill of materials to verify values; but in general, the cutoff
frequency will be around 5kHz – 10kHz to accommodate 100Hz switching. The
inductors have powder cores with relatively low permeability (60-90) and soft
saturation characteristics. The inductors and/or capacitors can be changed to
evaluate different filter designs.
Current sensing
Hall sensors U5 and U6 provide linear current feedback to the microcontroller.
These signals are used to control output power flow, to protect against over
current. Note that these are placed at an intermediate point of the output
filter. Refer to the bill of materials on page 7 to confirm the sensor part
numbers, but typical would be the MPS MCS1802GS-40-Psensor, which has a ±40A
range (100mV/A). These parts are pin-compatible with a ±5A and ±30A versions
of MCS1802GS, should lower ranges be desired. Note also that resistor dividers
scale the 5V outputs for the 3V range of the A/D.
Communication
Communication between the microcontroller and a computer is accomplished with
a mini USB cable to a JTAG microcontroller interface.
Control card
The microcontroller resides on a removable card, which inserts in a Samtec 60
pin socket on the inverter PCB. The socket can accept many of the DSPIC series
control cards from Microchip. The Microchip DSPIC33 PIM card supplied with
the kit provides capability to experiment with a wide variety of modulation
and control algorithms. It comes loaded with firmware to allow mmediate, out-
of-the-box, operation. Should the user wish to use an alternative
microcontroller family, an appropriate control card can be designed to insert
into the Samtec 60 pin socket.
Heatsink
The two TO-247 GaN FETs on each half-bridge are mounted on a common heatsink.
The heatsink is adequate for 3000W operation with forced air flow. Even
higher efficiency at high power may be achieved by minimizing the temperature
rise. This may be accomplished with stronger airflow. Alternately the
heatsinks could be replaced with larger and more effective ones.
Connections
Power for the AC output is derived from the high-voltage DC input. This will
typically be a DC power supply with output voltage up to 400VDC. A ~22µF, low
ESR film capacitor is provided as a bypass capacitor for the high voltage
supply, along with several lower valued ceramic capacitors in parallel. This
is not intended to provide significant energy storage. It is assumed that the
power supply or preceding DC-DC stage contains adequate output capacitance.
The control, communication, and gate-drive circuits are all powered from a
single 12V input (VCC). The wall-plug adaptor provided generates the
appropriate voltage (typically 12V) and power level.
Note that all signals on the board are referenced to the negative terminals of
the high and low voltage supplies, which are tied together on the PCB. The
heatsinks are also connected to the negative terminals of the supplies.
Powering on the board
-
Refer to Figure 4. Insert the microcontroller card to the 60 pin socket before applying any power to the board.
-
Before turning on the supply, connect the high-voltage power supply to the +/- inputs (J2 and J3). DO NOT apply too much force to the J2 and J3 connectors, as excessive force may bend and/or crack the PCB.
-
If a load is to be used, connect the load to the output terminals (J4 and J5). DO NOT apply too much force to the J4 and J5 connectors, as excessive force may bend and/or crack the PCB.
-
Insert the VCC (12V) plug to jack J1. LED1 should illuminate, indicating power is applied to the 5V and 3.3V regulators.
Depending on the specific control card used, one or more LEDs on the control card will also illuminate, indicating power is applied. A flashing LED indicates the firmware is executing. -
To use the pre-loaded firmware, no computer connection is required. If a computer connection is required for code modification, connect the USB cable from the computer to the USB connector on the microcontroller.
-
Turn on the high-voltage power. The high-voltage supply may be raised gradually.
Powering off the board
- Switch off high-voltage DC supply
- Power off 12V aux supply
Test overview
Figure 5 shows typical waveforms. The negative terminal of the high-voltage
supply is a convenient reference for the oscilloscope measurements, provided
there are not multiple connections to earth ground. 
Typical efficiency results are shown in Figure 6. These data points correspomeasured with a nd to efficiency measurements made in still air with 30 minutes’ dwell at each power level. Input power from the 400VDC source and output power to a resistive load were Yokogawa WT1800 power analyzer.
Design details
See Figures 7 and 8 for a detailed circuit schematic and Figure 9 for the PCB layers (also included in the design files). The parts list can be found in Table 1.
Table 1. TDINV3000W050B evaluation board bill of materials (BOM)
Qty| Value| Device| Parts| Manufacturer| Part
Number
---|---|---|---|---|---
2| | 5298021302500G _PINS| HS1. HS2| Aavid Thermalloy| 530002802500G
4| | KEYSTONE_7691| J2. 13. J4.15| Keystone| 7691
2| | LEDCHIP-LED0805| LED1. LED2| Rohm| SML-211UTT86
1| | PJ-002AH| 11| CUI Inc| P1-002AH
---|---|---|---|---|---
10| | TESTPOINT-KEYSTONE5015| TP1, TP2, TP3, TP4, TP5, TP6, TP7, TP8, TP9,
TP10| DNI| DNI
1| V7805-
500| V7805-500| U8| CUI Inc| 102-1709-ND
12| .1u| C-USC0603| C1, C10, C13, C14, C15, C16, C19, C20, C21, C22, C25, C27|
AVX| 06033C104JAT2A
2| .1u| C-USC0805| C8, C9| AVX| 08053C104KAT2A
1| 0| R-US_R1206| R3| Panasonic| ERJ-8GEYOROOV
2| 100k – SI8274| R-US_R0603| R21, R25| Panasonic| ERJ-3GEY1104V
8| 1.6M| R-US_R1206| R33, R34, R35, R36, R37, R38, R39, R40| Panasonic| ERJ-
8ENF1604V
1| 1k| R-US_R0805| R1| Panasonic| ERJ-6GEY1102V
2| in| C-USC0805| C7, C12| CUI Inc| 06033D102KAT2A
2| in dni| C-USC0603| C26, C28| DNI| DNI
1| 2U B32674D 6225K| 832674D6225K| C42| Epcos| 832674D6225K
2| 5.23k| R-US_R0603| R18, R23| Panasonic| ERJ-3EKF5231V
1| 9.09k| R-US_R1206| R32| Panasonic| ERJ-8ENF9091V
2| 10| R-US_R0805| R7, R9| Panasonic| ERJ-6GEYJ100V
4| 10| R-US_R1210| R45, R46, R48, R49| Yageo| AC1210FR-071ORL
2| 10.2k| R-US_R0603| R19, R24| Panasonic| ERJ-3EKF1022V
4| 10k| R-US_R0603| R11, R13, R15, R17| Panasonic| ERJ-3GEY1103V
4| 10k| R-US_R1206| R41, R43, R44, R51| Yageo| RC1206FR-0710KL
4| 10n / 630V| C-EUC1206| C34, C35, C38, C39| Murata| GRM3113R72.1103KW01 L
4| 10p| C-USC0603| C5, C36, C37, C40| Kemet| C0603C100J3HAC7867
---|---|---|---|---|---
4| 10u| C-EUC0805| C17, C18, C23, C24| Kemet| C0805C106M4PACTU
1| 10u| C-USC1206| C4| AVX| CL31A106KAHNNNE
2| 150k| R-US_R0603| R4, R5| Yageo| RC0603FR-07150KL
8| 20 DNI| R-US_R1206| RSN1, RSN2, RSN3, RSN4, RSN5, RSN6, RSN7, RSN8| DNI|
DNI
1| 22u| C-USC1206| C2| Samsung Electronics| CL31A226KAHNNNE
4| 35| R-US_R0603| R10, R12, R14, R16| TE Connectivity| RP73PF1134R8BTDF
2| 0 – SI8274| R-US_R0603| R20, R22| Panasonic| ERJ-3GEYOROOV
2| 100nF| C-EUC1206| C31, C32| Samsung Electronics| CL31F104MBCNNNC
1| 100pF (10y)| C-USC0603| C33| Wurth Electronics| 885012006008
4| 100pF DNI| C-EUC1206| CSN1, CSN2, CSN3, CSN4| DNI| DNI
2| 100u| PANASONICFPV| C3, C11| Panasonic| EEE-FPE101XAP
4| 120| R-US_R0603| FB1, FB2, FB3, FB4| Murata| BLM18KG121TH1D
1| 220| R-US_R1206| R42| Yageo| RC1206JR-07220RL
2| 220pF| C-EUC1206| C29, C30| Wurth Electronics| 885012008014
2| 440uH| 440uH| L1, L2| mps| P11055
1| 348| R-US_R0805| R2| Panasonic| ERJ-6ENF3480V
4| 680k| R-US_R1206| R28, R29, R30, R31| Panasonic| ERJ-P08J684V
2| ESL’| DIODE-D0-214AC| D1, D2| Fairchild| ES1J
2| MCS1802 GS-40-P| MCS1802GS-40-P| U5, U6| MPS| MCS1802GS-40-P
1| MECF-30- 01-L-DVWT| MECF-30-01-L-DV-WT| U$1| Samtec Inc|
MECF-30-01-L-DV-V/T
---|---|---|---|---|---
1| MKP1848 622454P 4 / 630V| MK P1848622454P4| C6| Vishay| MKP1848625454P4
1| 0PA2350 UA/2K5| OP _IC| U7| Texas Instruments| OPA2350UA/2K 5
2| SI8274| SI8274| U3, U4| SiLabs| SI8274GB1-1S1R
4| TP65H05 0G4WS| TP65H050G4WS| Q1, Q2, Q3, Q4| Transphorm| TP65H050G4WS
1| TPS79533| TPS79533| U1| TI| TPS79533DCQR
2| dni .1u| C-USC2225K| C43, C44| DNI| DNI
2| THERMAL PAD| BETWEEN TP65H050G4WS (Q1, Q3) AND HEATSINK| BETWEEN
TP65H050G4WS (Q1, Q3) AND HEATSINK| Aavid Thermal loy| 4169G
2| 4-40 SCREW| “screw on TP65H050G4WS to heatsink| “screw on TP65H050G4WS to
heatsink| B&F| PMSSS 440 0063 PH
5| bumper cylin
0.312″ dia blk| To place under PCB (5 locations: 4 each corner, 1 in the
middle| To place under PCB (5 locations: 4 each corner, 1 in the middle| 3M|
SJ-5003 (BLACK)
Probing
There are two available Tektronix test points on the PCB used to monitor the
low-side switching (node) capability of each halfbridge circuit during
operation.
The board has eight other test point locations for probing: VCC, VDD, SN1,
SN2, GS1, GS2, GND, and GND.
To minimize inductance during measurement, the tip and the ground of the probe
should be directly attached to the sensing points to minimize the sensing
loop. For safe, reliable, and accurate measurement, a scope probe tip may be
directly soldered to the low-side FET drain and a short ground wire soldered
to the low-side FET source. See Figure 10 for an alternative that does not
require soldering the probe tip.
Protection features
Current limit
The TDINV3000W050B evaluation board supports user-defined current limit
thresholds in both the positive- and negative-going directions. The current
limit is 30A.