[Test] Evaluation for Maximum Thermostat TEC Output Power #51

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linuswck · 2024-10-14T13:37:50+08:00

linuswck commented

2024-10-14 13:37:50 +08:00

Description

Kirdy can be powered via the 12V power jack, Ethernet port through PoE in IEEE 802.3af(Class 3) and IEEE 802.3at(Class 4) standards. Among the 3 power options, PoE Class 3 has smallest input power limit.

IEEE 802.3af Class 3 guarantees Power Device(PD)(Kirdy) input power to be at least 12.95W and the Power sourcing equipment(PSE) should supply 15.4W max. Upon test with hardware, if the PD input power limit is exceeded, either the MCU restarts due to power failure or the PSE cuts off power and then power up the PD again.

This report evaluates the safe TEC output power range with max LD output current set.

Test Setup

Here highlights the relevant setup parameters.

Kirdy:

LD Output Current: 300mA
LD Terminals are short internally
Thermostat Max V: 4V
Thermostat Max IPos and Max INeg: 3A
Thermostat operates in constant current mode
Both LD and Thermostat are powered on

Electronic Load:

Set to 1Ohm Constant Resistance mode

Measurement Equipment:

Netgear GS108PEv3 PoE+ Switch
Fluke 87V for 12V Input Current measurement
Siglent SDL1020X-E Electronic Load for TEC load
FILR One Thermal Camera

Result

Ambient Temperature is 24.6 Degree. Kirdy is placed in an opened test bench with free access to ambient air flow. The hottest components on Kirdy is the Max1968 TEC Driver.

Here shows the result with maximum achievable TEC Output Power set.

Input Power: PD 12V 1.110A -> PoE Input Power: 15.136W
TEC Output Power: 4.047W (2.0126V 2.011A)
Temperature ofMax1968 is 69.7 degree (Max Operating Temperature: 85 degree)

If we stick to the 12.95W input power limit, here is the result.

Input Power: PD 12V 0.950A -> PoE Input Power: 12.954W
TEC Output Power: 2.85W (1.69V 1.689A)
Temperature of Max1968 is 63.1 degree(Max Operating Temperature: 85 degree)

Note1: Assume 88% efficiency for the SDAPO PM1202 PoE Module(Taken from manufacturer's website)
Note2: Negative TEC polarity is slightly more efficient than the positive TEC polarity

Additional Test for TEC Output Power Limit when external 12V Power Source is connected: Here is the test result.
Maximum TEC Output Power Recorded

Input Power 12V 1.679A
TEC Output Power: 9.59W (3.8V 2.5424A)
Electronic Load Resistance: 1.504ohm
Operating Temperature: 74 Degree

Another condition where the operating temperature of the TEC Driver can be exceeded.

Input Power 12V 1.637A
TEC Output Power: 7.579009W (2.7530V 2.7530A)
Electronic Load Resistance: 1.000ohm
Operating Temperature: 97.5 Degree

### Description Kirdy can be powered via the 12V power jack, Ethernet port through PoE in IEEE 802.3af(Class 3) and IEEE 802.3at(Class 4) standards. Among the 3 power options, PoE Class 3 has smallest input power limit. IEEE 802.3af Class 3 guarantees Power Device(PD)(Kirdy) input power to be at least 12.95W and the Power sourcing equipment(PSE) should supply 15.4W max. Upon test with hardware, if the PD input power limit is exceeded, either the MCU restarts due to power failure or the PSE cuts off power and then power up the PD again. This report evaluates the safe TEC output power range with max LD output current set. ### Test Setup Here highlights the relevant setup parameters. Kirdy: - LD Output Current: 300mA - LD Terminals are short internally - Thermostat Max V: 4V - Thermostat Max IPos and Max INeg: 3A - Thermostat operates in constant current mode - Both LD and Thermostat are powered on Electronic Load: - Set to 1Ohm Constant Resistance mode Measurement Equipment: - Netgear GS108PEv3 PoE+ Switch - Fluke 87V for 12V Input Current measurement - Siglent SDL1020X-E Electronic Load for TEC load - FILR One Thermal Camera ### Result Ambient Temperature is 24.6 Degree. Kirdy is placed in an opened test bench with free access to ambient air flow. The hottest components on Kirdy is the Max1968 TEC Driver. Here shows the result with maximum achievable TEC Output Power set. - Input Power: PD 12V 1.110A -> PoE Input Power: 15.136W - TEC Output Power: 4.047W (2.0126V 2.011A) - Temperature ofMax1968 is 69.7 degree (Max Operating Temperature: 85 degree) If we stick to the 12.95W input power limit, here is the result. - Input Power: PD 12V 0.950A -> PoE Input Power: 12.954W - TEC Output Power: 2.85W (1.69V 1.689A) - Temperature of Max1968 is 63.1 degree(Max Operating Temperature: 85 degree) Note1: Assume 88% efficiency for the SDAPO PM1202 PoE Module(Taken from manufacturer's website) Note2: Negative TEC polarity is slightly more efficient than the positive TEC polarity Additional Test for TEC Output Power Limit when external 12V Power Source is connected: Here is the test result. Maximum TEC Output Power Recorded - Input Power 12V 1.679A - TEC Output Power: 9.59W (3.8V 2.5424A) - Electronic Load Resistance: 1.504ohm - Operating Temperature: 74 Degree Another condition where the operating temperature of the TEC Driver can be exceeded. - Input Power 12V 1.637A - TEC Output Power: 7.579009W (2.7530V 2.7530A) - Electronic Load Resistance: 1.000ohm - Operating Temperature: 97.5 Degree

linuswck referenced this issue

2024-10-17 11:30:57 +08:00

Add Heat Sink to MAX1968 and its Inductors #52

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Reference: sinara-hw/kirdy#51