QS 100 LSM Power Management

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Bernadette Melton
5 years ago
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1 Revision A

2 Table of Contents Revision History...2 Overview...3 Soft Start not complete fault...3 Under voltage fault...4 Under voltage warning limit...5 Over voltage maximum limit...5 Over voltage warning limit...7 Managing excessive +48 V internal propulsion bus voltages within the QS 100 stator...7 Coil/block level power management (software enabled)...7 Hardware power management (in hardware)...10 List of Figures Figure 1: High level detail of soft start circuit within the QS Figure 2: Soft start not complete messaging behavior... 4 Figure 3: Under voltage messaging behavior... 5 Figure 4: Inverter status and OV fault behavior... 6 Figure 5: Coil/individual block current vs. +48 V internal propulsion bus voltage (10 msec filter applied)... 8 Figure 6: Coil/individual block current vs. +48 V internal propulsion bus voltage with Slave code version or higher (1 msec filter applied)... 9 Figure 7: Power dissipation per block vs. +48 V internal propulsion bus voltage... 9 Figure 8: Power dissipation per block vs. +48 V internal propulsion bus voltage for slave code version greater than Figure 9: 10 Ohm resistor power dissipation vs. +48 V internal propulsion bus voltage Revision History Rev. Date Author Description A 3/2/2015 E. Wildi Initial release 2015 MagneMotion, Inc. Page 2 of 11

3 Overview The QS 100 platform is designed to operate at a nominal 48 VDC +/-5% bias. However voltage drops in the power distribution system when delivering power to the stator(s) and voltage increases during regeneration events will lead to fluctuations in the voltages seen at the QS stator terminals. How voltage conditions at the QS are managed and communicated is the object of this document. Soft Start not complete fault The QS inverters are enabled when the filtered QS V internal propulsion bus (after the soft start circuitry, see Figure 1) rises above 43 V. Until this voltage is reached, the QS motor status through the HLC will report a soft-start not complete and the system will not allow vehicle motion to occur. Once this internal voltage is reached, the system will support vehicle motion and operate as intended (soft start switch closed). If the internal bus voltage drops below 41 V during operation, the soft-start switch will open and the motor status through the HLC will report a soft start not complete message to the host (refer to either the Host Controller TCP/IP Communication Protocol User s Manual, the Host Controller EtherNet/IP Communication Protocol User s Manual, or the Mitsubishi PLC TCP/IP Library User s Manual). All inverters within this QS 100 stator will be disabled and any vehicles in motion over this stator will no longer be under active control and as such their motion will be undefined. Soft Start QS V propulsion Soft start resistor +48 V internal propulsion bus Switch 10 Ohm +48 V return Figure 1: High level detail of soft start circuit within the QS 100 Normal operation will resume (soft start switch closed) once the internal propulsion bus gets back up to 43 V; the motor status for the soft start error message will automatically self-clear at that time. This messaging behavior is illustrated in Figure 2. Not shown, is the additional constraint that the voltage across the soft start resistor shown in Figure 1 must be < 2 V to allow the switch to close and thereby prevent a soft start not complete error message to appear MagneMotion, Inc. Page 3 of 11

4 A soft start fault may be due to an internal failure within the QS 100 or more likely, a result of the voltage applied to the QS V propulsion bus being too low. 41 V 43 V +48 V internal propulsion bus voltage (filtered) Under voltage fault Figure 2: Soft start not complete messaging behavior An under voltage fault will be declared and reported to the host (refer to either the Host Controller TCP/IP Communication Protocol User s Manual, the Host Controller EtherNet/IP Communication Protocol User s Manual, or the Mitsubishi PLC TCP/IP Library User s Manual), when the +48 V propulsion filtered voltage measured at the QS 100 is below +43 V upon initial power up. Once this fault clears, it will only re-appear if the filtered +48 V propulsion voltage drops below +41 V. The QS motor status through the HLC will reports this under voltage fault. This fault self-clears when the filtered +48 V propulsion input voltages rises back to >43 V. The behavior of this fault messaging is illustrated in Figure 3. This fault is likely due to excessive +48 V propulsion / +48 V return cable resistance from the 48 V power source to the QS or to an internal failure within the QS 100 that is significant enough to collapse the +48 V propulsion voltage at the QS 100 proper. This fault message is only available on systems that run the following software. It is not active on prior software version: NC version or higher Master version or higher Soft start not complete error will be reported No soft start not complete error will be reported 2015 MagneMotion, Inc. Page 4 of 11

5 41 V 43 V +48 V propulsion voltage (filtered) Under voltage warning limit Figure 3: Under voltage messaging behavior When the QS V propulsion bus drops below 42.5 V, an under voltage warning will be logged by the HLC when the Log Level for Faults is set to the Warning level (refer to the Node Controller Web Interface User s Manual). This warning is not pushed to the host. When the voltage rises back up to 43 V this fault will self-clear. There is no voltage filtering associated with this warning since the intent is to capture maximum voltage excursions. Upon initial system power up, this fault will be present and persist until the propulsion bus reaches 43 V. The intent of this feature is to verify proper cabling and power distribution for new systems and may be used to do periodic assessment of the system to make sure no degradation has occurred. A properly designed system should never exhibit this alarm following system power up. This feature is available only on systems running the following code base or higher: NC version or higher Master version or higher Under voltage error will be reported Over voltage maximum limit No under voltage error will be reported Based on the specific system wiring and vehicle activity, it is possible for regenerated power resulting from vehicle decelerations to cause the QS +48 V propulsion bus voltage to rise to excessive levels and MMI has implemented protective features to guard against operating conditions that could damage the motor. Since the source of such a condition is due to regeneration effects associated with active braking or deceleration of a vehicle (loaded or unloaded) over the stator, a means (among others) of eliminating such regenerated power is to shut down the QS inverters MagneMotion, Inc. Page 5 of 11

6 When the QS V propulsion bus reaches 59 V, the QS 100 inverters are shut down thereby eliminating any regeneration effects within this stator (assuming this stator contributes to regeneration). Vehicle arrays over this stator will no longer be under active control and therefore will no longer decelerate as intended. An over voltage fault will be reported to the host when this condition is detected (refer to either the Host Controller TCP/IP Communication Protocol User s Manual, the Host Controller EtherNet/IP Communication Protocol User s Manual, or the Mitsubishi PLC TCP/IP Library User s Manual). To avoid issuing an over voltage fault to the host due to spurious noise, the +48 V propulsion voltage used to trigger this event is filtered. This error message and the associated fault will persist until the filtered voltage at the QS V propulsion bus drops below 57 V. At this time the system will attempt to resume active control of the vehicle. This inverter status behavior is shown in Figure 4. There are several possible solutions available to eliminate a fault of this type. Specifically: 1. Reduce cable resistance between stators that share a common +48 V propulsion supply if voltage drops in these cables leads to excessive voltages on stator(s) undergoing regeneration. 2. Reduce maximum speed and/or maximum accelerations to reduce the amount of regenerated power flowing back into the system. 3. Increase spacing between vehicles on stators sharing a common +48 V propulsion supply to increase the number of blocks available to absorb power during regeneration. 4. Connect more QS 100 stators to a common +48 V propulsion supply to increase the number of blocks available to absorb regenerated power. 5. If all of the above resolution paths have been explored and the problem still persists, the only solution is to add an active voltage clamp across the +48 V propulsion supply local to the power supply or to the QS 100 stator(s) that are exhibiting this issue. The clamping voltage should be above 51 V but kept as low as possible. 57 V 59 V +48 V propulsion voltage (filtered) Inverter operational and no OV fault declared Inverter disabled and OV fault reported Figure 4: Inverter status and OV fault behavior 2015 MagneMotion, Inc. Page 6 of 11

7 Over voltage warning limit When the QS 100 master board detects instantaneous voltages in excess of 57 V on its +48 V propulsion bus, an over voltage warning will be issued to the HLC when the Log Level for Faults is set to the Warning level (refer to the Node Controller Web Interface User s Manual). This warning fault is not pushed to the host and will self-clear once the +48 V propulsion bus voltage drops below 56.5 V. The intent of this feature is to verify proper cabling and power distribution for new systems and to support periodic assessments of the system to make sure no degradation has occurred. Any warnings observed as part of system commissioning need to be addressed and resolved using one or several of the resolution methods described above under over voltage faults. The warning feature is only available on systems operating with the following code base: NC version or higher Master version or higher Managing excessive +48 V internal propulsion bus voltages within the QS 100 stator To supplement any external power management schemes applied to a QS 100 system, a means of internally consuming regenerated power within a QS 100 stator is incorporated as a product feature. Coil/block level power management (software enabled) When the filtered +48 V internal propulsion bus reaches 53 V, current will begin to ramp in coils/blocks that are available to effectively allow the QS stator to absorb/ dissipate power due to regeneration within itself or coming from other QS 100 stators connected on a commonly shared +48 V power supply. The current in these available blocks ramps linearly to 5 A over a 2 volt range from 53 V to 55 V in this case. The coil current remains constant at 5 A for voltages above 55 V and drops to zero for voltages above 59 V (since all inverters are turned off as outlined above). This behavior is shown in Figure MagneMotion, Inc. Page 7 of 11

8 Figure 5: Coil/individual block current vs. +48 V internal propulsion bus voltage (10 msec filter applied) For slave software version or higher, the voltage at which coil current initiates has been reduced to 51.5 V. The linear ramp from 0 to 5 A occurs between 51.5 V and 53.5 V and is maintained at 5 A above this level until voltages reach 59 V. This behavior is shown in Figure 6. The voltage filtering is also less aggressive (1 msec) in this code version. For slave software version or higher, the number of coils available to absorb power has been increased. In prior slave code versions, coils that were under the vehicle as configured (typically longer than the vehicle magnet array length) and coils allocated ahead of a vehicle in motion (associated with brick wall headway) were not used to absorb power. For vehicles that are appreciably longer than the magnet array and/or for vehicles that are travelling at their maximum velocity in a convoy, this represents an appreciable number of blocks. The new slave code maximizes the number of blocks available to absorb power. Specifically, a coil block is available and will be used to dissipate power within a QS 100 stator if its neighboring block (upstream and downstream) does not have a magnet array spanning it. Note that a neighboring block may be within a different QS 100 stator as would be the case for the first and last blocks within a given QS 100 stator MagneMotion, Inc. Page 8 of 11

9 Figure 6: Coil/individual block current vs. +48 V internal propulsion bus voltage with Slave code version or higher (1 msec filter applied) For a nominal coil/block resistance of 1.9 Ohm, the dissipated power will be 47.5 W per block when the 5 A current level is reached and will remain at this level up to 59 V. The dissipated power vs V internal propulsion bus voltage for both slave code base versions is shown in Figure 7 and Figure 8. Figure 7: Power dissipation per block vs. +48 V internal propulsion bus voltage 2015 MagneMotion, Inc. Page 9 of 11

10 For the legacy slave code base, when the +48 V internal propulsion bus is between 53 V and 55 V, the power dissipated per block can be expressed as: * (+48 V internal propulsion bus - 53) 2 Watts. For the slave code base or higher, when the +48 V internal propulsion bus is between 51.5 V and 53.5 V, the power dissipated per block is: * (+48 V internal propulsion bus 51.5) 2 Watts Figure 8: Power dissipation per block vs. +48 V internal propulsion bus voltage for slave code version greater than The QS m stator has 10 blocks and the QS 100 ½ m has 5 blocks. Therefore, the maximum power each stator can absorb is 475 W and W respectively. Hardware power management (in hardware) When the + 48 V internal propulsion voltage rises above 58.9 V, a 10 Ohm resistor within the QS 100 is switched across +48 V propulsion and +48 V return as shown in Figure 1. This internal load will remain active for voltages higher than this voltage and will be removed when the voltage goes below 56.9 V. The power dissipated by this load, shown in Figure 9, is additive to any power dissipated by the coils/blocks as outlined above MagneMotion, Inc. Page 10 of 11

11 Figure 9: 10 Ohm resistor power dissipation vs. +48 V internal propulsion bus voltage The power dissipation through this 10 Ohm resistor can be expressed as: (+V propulsion) 2 /10 Watts At 58.9 V this translates to 347 W and at 56.9 V it would be 324 W. Under normal use conditions, this resistor should never be activated or be relied upon to absorb regeneration power. This resistor is meant to handle anomalous high voltage transients that might otherwise lead to a catastrophic voltage induced stator failure MagneMotion, Inc. Page 11 of 11

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