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Test Report

200 A Regen to 79 °C — Gen7 Size 2

Gen7 size 2 regenerative run at a nominal 50 V bus and 200 A q-axis command, analyzed through the first 79 °C baseplate NTC (TS2) reading with heatsink contact gap and no thermal interface material.

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Document Information

Document IDOV-TEST-HW-REGEN-200A-GEN7-SIZE2
Test ID13
Version0.3
Date2026-09-22
Applies toopenvvvf-control-module, chassis-size-2
Product lineopenvvvf
Normative referencesOV-TEST-HW-INDEX
Index / Safety and Compliance / Testing and Validation / Hardware Tests / 200 A Regen to 79 °C — Gen7 Size 2 / 200 A Regen to 79 °C — Gen7 Size 2
13 · v0.3 · 2026-09-22Download PDF
DoctypeTest Report
Product lineopenvvvf
Applies toopenvvvf-control-module, chassis-size-2
Version0.3
Date2026-09-22
DescriptionGen7 size 2 regenerative run at a nominal 50 V bus and 200 A q-axis command, analyzed through the first 79 °C baseplate NTC (TS2) reading with heatsink contact gap and no thermal interface material.
Test id13
Nav order362
Normative refsOV-TEST-HW-INDEX

200 A Regen to 79 °C — Gen7 Size 2

This report covers the first portion of a regenerative dynamometer run on Gen7 size 2 hardware. The inverter was commanded in 25 A steps to 200 A q-axis current, then held there until baseplate temperature sensor TS2 (temp_inv2_c) first reached 79 °C. The selected analysis interval ends at t = 619.492 s, 9 min 15 s after the 200 A command. Over the 200 A hold to that point, the logged DC link received about 3.14 kW on average, or approximately 0.485 kWh total.

A heatsink was fitted for this run, unlike the 100 A test, but no thermal interface material was used. The phase leads tilted the heatsink backward and left a gap at the thermal interface. The temperatures here describe that as-tested assembly and do not establish heatsink performance with correct contact.

Telemetry boundary: The 79 °C sample is the report split point. The source log does not show the 200 A command being removed at that instant; it continues into the thermal OTP event documented in OV-TEST-HW-THERMAL-OTP-200A-GEN7-SIZE2. The two reports are separate analyses of that continuous recording.

Test setup

  • DUT: OpenVVVF Gen7 size 2 inverter hardware.
  • Cooling assembly: Heatsink installed without thermal interface material. Phase-lead interference tilted it backward and left a gap at the contact surface.
  • Machine: Motor coupled to a Sierra CP Engineering dynamometer; telemetry during the 200 A hold indicates approximately −1,100 RPM.
  • DC supply: Nominal 50 V setting. The measured bus rose under regeneration.
  • Instrumentation: RTE Studio telemetry, Tektronix 5 Series MSO, and Klein Tools TI250 thermal imager.
Dynamometer test setup
Dynamometer test setup
Second view of the dynamometer and motor
Second view of the dynamometer and motor
Oscilloscope capture during the regenerative run
Oscilloscope capture during the regenerative run
RTE Studio telemetry screen during the run
RTE Studio telemetry screen during the run

Test conditions

Parameter Value
Hardware Gen7 size 2
Nominal bus setting 50 V
Bus during 200 A hold 58.1 V average; 51.5–58.9 V range through the 79 °C split
Current command IqVar: 25, 50, 75, 100, 125, 150, 175, then 200 A
Time at 200 A to 79 °C split 9 min 15 s
Average DC-link power at 200 A 3.14 kW into the DC link
Regen energy through split Approximately 0.485 kWh, integrated from logged DC-link power
Heatsink interface No thermal interface material; visible gap caused by phase-lead interference

Procedure

  1. Enabled the inverter and allowed the dynamometer to bring the coupled machine to operating speed.
  2. Increased IqVar in the recorded 25 A steps through 200 A.
  3. Held the 200 A command while logging telemetry and observing the baseplate NTCs.
  4. Split this report at the first temp_inv2_c (TS2) sample at or above 79 °C, at t = 619.492 s. The remainder of the same source recording is analyzed in the OTP report.

Electrical results

Per-command statistics from the full-rate telemetry log through the 79 °C analysis boundary (Pdc = DC-link power, Idc = DC-link current):

Iq command Step duration Avg Iq Peak phase current Avg Pdc Avg Idc
25 A 3.8 s 22.4 A 33 A 390 W 8 A
50 A 1.9 s 44.5 A 53 A 713 W 14 A
75 A 1.5 s 69.5 A 83 A 1.06 kW 21 A
100 A 1.5 s 93.9 A 110 A 1.42 kW 28 A
125 A 1.2 s 118.6 A 135 A 1.89 kW 38 A
150 A 1.9 s 146.0 A 162 A 2.37 kW 48 A
175 A 1.6 s 168.8 A 187 A 2.73 kW 53 A
200 A hold to split 9 min 15 s 200.0 A 224 A 3.14 kW 54.0 A

During the 200 A interval to the split, measured bus voltage averaged 58.1 V and peaked at 58.9 V. Instantaneous phase-current samples reached approximately +224 A and −208 A. The data show sustained regenerative power flow throughout the analyzed interval.

Thermal results

At the selected split point, temp_inv2_c (baseplate TS2) first crossed 79 °C. Temperatures rose from the initial NTC readings as follows:

  • Baseplate TS1 (temp_inv1_c): 34.5 °C → 76.7 °C at the split.
  • Baseplate TS2 (temp_inv2_c): 37.6 °C → 79.0 °C at the split.

The TI250 photos show exterior spot readings of 42.1 °C, 32.9 °C, and 39.2 °C. These are individual crosshair measurements on auto-scaled thermal images and are not a full surface-temperature survey.

TI250 thermal view 1, crosshair at 42.1 °C
TI250 thermal view 1, crosshair at 42.1 °C
TI250 thermal view 2, crosshair at 32.9 °C
TI250 thermal view 2, crosshair at 32.9 °C
TI250 thermal view 3, crosshair at 39.2 °C
TI250 thermal view 3, crosshair at 39.2 °C
TI250 thermal view 4
TI250 thermal view 4

Telemetry overview

Telemetry through the first 79 °C reading: Iq, DC-link power, baseplate NTCs, and bus voltage
Telemetry through the first 79 °C reading: Iq, DC-link power, baseplate NTCs, and bus voltage

Open split telemetry: View the run through 79 °C in the Telemetry Viewer

Observations

  • The inverter reached the 79 °C reporting boundary after 9 min 15 s at the 200 A command, with approximately 3.14 kW average returned to the DC link.
  • No fault state is recorded before the split point.
  • The telemetry is continuous across the split. It does not show IqVar being set to zero at 79 °C; the current remains at the 200 A command until the OTP trip described in the companion report.
  • The logged bus averaged 58.1 V under regeneration, although the bench supply was set for nominal 50 V.
  • Machine-terminal power is not quoted for this run: P = (3/2)(vd·id + vq·iq) from this session's logged dq voltages (firmware build cd4d65f5c2181738) does not reconcile with DC-link power — it would imply ≈3 kW of inverter dissipation, which the observed temperature rise (44 K in 10 minutes on the dry-mounted heatsink) rules out. The dq-voltage calculation reconciles in the later build 855dbcee90d611cb and is reported from the 400 A run onward.
  • The heatsink gap and absent thermal interface material prevent this run from establishing the thermal performance of a correctly mounted heatsink.
  • temp_inv3_c (TS3) and temp_motor_c are unpopulated in this recording.

Conclusion

Pass for the 200 A regenerative heating segment through 79 °C. Gen7 size 2 hardware sustained the 200 A q-axis command while returning approximately 3.14 kW to the DC link, reaching the selected 79 °C sensor threshold without a fault before the report boundary. The source recording continues into a thermal OTP event; that response is documented separately. Temperature conclusions apply only to this assembly, where the heatsink had a gap and no thermal interface material.

Artifacts