4.9. Drivetrain Electric Power Limiter - EltPwrLim

• Overview

• Functions

• Ports

• Parameters

• Calibration

Id	EltPwrLim
Version	0.3.1.0
Title	Drivetrain Electric Power Limiter
System	Drivetrain
Document Type	Application Software Component Specification Preview

4.9.1. Overview

The Electric Power Limiter component limits the total electric power of the vehicle drivetrain based on battery charge and discharge power limits. It calculates torque limits to constrain the total power within the specified battery power limits.

4.9.2. Functions

	Title	Description
1	Calculate Discharge Power Limit	Determines the battery discharge power limit based on configurable discharge power limits for different time scales (2 sec, 10 sec, 30 sec). Filters the selected discharge power limit.
2	Calculate Charge Power Limit	Determines the battery charge power limit based on configurable charge power limits for different time scales (2 sec, 10 sec, 30 sec). Filters the selected charge power limit.
3	Calculate Actual Power	Calculates the actual electric power of the drivetrain motors based on measured motor speeds and torques. Provides options to use measured HV bus power or calculate power from motor speeds and torques.
4	Limit Discharge Torque	Limits the total discharge (positive) torque request to constrain the drivetrain power within the battery discharge power limit. Uses a feedback and feedforward control structure with proportional, integral and derivative terms.
5	Limit Charge Torque	Limits the total charge (negative) torque request to constrain the drivetrain power within the battery charge power limit. Uses a feedback and feedforward control structure with proportional, integral and derivative terms.

4.9.3. Ports

	Id	Direction	Data Type	Dimensions	Unit	Description	Keywords
1	Ts	Incoming	single	[1]	s	Expected signal: Battery limits for discharge. HV system If signal is NA: any positive	Ts
2	BatPwrDchaMin30Sec	Incoming	single	[1]	W	Expected signal: Battery limits for discharge. HV system If signal is NA: any positive	Battery Power Discharge Minimum30 Second
3	BatPwrChMax30Sec	Incoming	single	[1]	W	Expected signal: Battery limits for charge. HV System If signal is NA: any negative	Battery Power Charge Maximum30 Second
4	BatPwrDchaMin10Sec	Incoming	single	[1]	W	Expected signal: Battery limits for discharge. HV System If signal is NA: any positive	Battery Power Discharge Minimum10 Second
5	BatPwrChMax10Sec	Incoming	single	[1]	W	Expected signal: Battery limits for charge. HV system If signal is NA: any negative	Battery Power Charge Maximum10 Second
6	BatPwrDchaMin2Sec	Incoming	single	[1]	W	Expected signal: Battery limits for discharge. HV system If signal is NA: any positive	Battery Power Discharge Minimum2 Second
7	BatPwrChMax2Sec	Incoming	single	[1]	W	Expected signal: Battery limits for charge. HV system If signal is NA: any negative	Battery Power Charge Maximum2 Second
8	MotAgrV	Incoming	single	[4]	rad/s	Expected signal: Motor speed (feedback from inverter) If signal si NA: mandatory.	Motor Angular Velocity
9	MotTqAct	Incoming	single	[4]	N*m	Expected signal: Totor torque (feedback from inverter) If signal si NA: mandatory. CmnenaGearSt.Fwrd or Rvs (coming from Gear Selector module)	Motor Torque Actual
10	VehSpd	Incoming	single	[1]	km/h	Expected signal: Vehicle Longitudinal speed If signal is NA: mandatory	Vehicle Speed
11	HvPwrAct	Incoming	single	[1]	W	Expected signal: feedbck from HV system on Power consumption If signal is NA: Sum of Power consumption from powertrain	Hv Power Actual
12	ElpwrlimAcv	Incoming	Enum: CmndrvTqSrc	[1]		Expected signal: Gear State If signal si NA: mandatory. CmndrvTqSrc	Elpwrlim Active
13	ElpwrlimWhlTqMax	Outgoing	single	[1]	N*m		Elpwrlim Wheel Torque Maximum
14	ElpwrlimWhlTqMin	Outgoing	single	[1]	N*m		Elpwrlim Wheel Torque Minimum
15	ElpwrlimPwrChLim	Outgoing	single	[1]	kW		Elpwrlim Power Charge Limit
16	ElpwrlimPwrDchaLim	Outgoing	single	[1]	kW		Elpwrlim Power Discharge Limit
17	ElpwrlimPwrAct	Outgoing	single	[1]	kW		Elpwrlim Power Actual

4.9.4. Parameters

	Id	Data Type	Dimensions	Range	Unit	Description	Keywords
1	ElpwrlimDchaPropIntglCtlMarg	single	[1,1]	Min: , Max:		Margin for activating PI contribution in discharge	Elpwrlim Discharge Proportional Integral Control Margin
2	ElpwrlimDchaDervCtlMarg	single	[1,1]	Min: , Max:		Margin for activating derivative contribution in discharge	Elpwrlim Discharge Derivative Control Margin
3	ElpwrlimDervTranTi	single	[1,1]	Min: , Max:	s	Transition time for derivative term	Elpwrlim Derivative Transition Time
4	ElpwrlimDchaLimrDervDcyRate	single	[1,1]	Min: , Max:	W/s	Decay rate for derivate term in discharge	Elpwrlim Discharge Limiter Derivative Decay Rate
5	ElpwrlimDchaLimrDervGain	single	[1,1]	Min: , Max:		Deritative gain for limiter in discharge	Elpwrlim Discharge Limiter Derivative Gain
6	ElpwrlimDchaLimrDervMax	single	[1,1]	Min: , Max:		Maximum relative derivative contribution in discharge	Elpwrlim Discharge Limiter Derivative Maximum
7	ElpwrlimAntiWndpGain	single	[1,1]	Min: , Max:		Anti-windup gain	Elpwrlim Anti Windup Gain
8	ElpwrlimBatPwrDchaFil	single	[1,1]	Min: , Max:		Discharge Power limit filter cut-off frequency	Elpwrlim Battery Power Discharge Filter
9	ElpwrlimBatPwrChSeln	uint8	[1,1]	Min: 0, Max: 2		HV electrical source power limitation selection when charging: 0- 30 seconds, 1- 10 seconds, 2- 2 seconds, default (30 seconds)	Elpwrlim Battery Power Charge Selection
10	ElpwrlimBatPwrDchaGain	single	[1,1]	Min: , Max:	1	Electrical power limitation Battery power discharge gain	Elpwrlim Battery Power Discharge Gain
11	ElpwrlimBatPwrDchaMax	single	[1,1]	Min: 0, Max: 1000000000	W	Maximum discharge power limit	Elpwrlim Battery Power Discharge Maximum
12	ElpwrlimBatPwrDchaOfs	single	[1,1]	Min: , Max:	W	Electrical power limitation Battery power discharge offset	Elpwrlim Battery Power Discharge Offset
13	ElpwrlimBatPwrDchaSeln	uint8	[1,1]	Min: 0, Max: 2		HV electrical source power limitation selection when disharging: 0- 30 seconds, 1- 10 seconds, 2- 2 seconds, default (30 seconds)	Elpwrlim Battery Power Discharge Selection
14	ElpwrlimBatPwrChFil	single	[1,1]	Min: , Max:		Charge Power limit filter cut-off frequency	Elpwrlim Battery Power Charge Filter
15	ElpwrlimBatPwrChGain	single	[1,1]	Min: , Max:	1	Electrical power limitation Battery power charge gain	Elpwrlim Battery Power Charge Gain
16	ElpwrlimBatPwrChMin	single	[1,1]	Min: -1000000000, Max: 0	W	Minimum Charge power limit (negative values expected)	Elpwrlim Battery Power Charge Minimum
17	ElpwrlimBatPwrChOfs	single	[1,1]	Min: , Max:	W	Electrical power limitation Battery power charge offset	Elpwrlim Battery Power Charge Offset
18	ElpwrlimChDervCtlMarg	single	[1,1]	Min: , Max:		Margin for activating derivative contribution in charge	Elpwrlim Charge Derivative Control Margin
19	ElpwrlimChLimrDervDcyRate	single	[1,1]	Min: , Max:	W/s	Decay rate for derivate term in charge	Elpwrlim Charge Limiter Derivative Decay Rate
20	ElpwrlimChLimrDervGain	single	[1,1]	Min: , Max:		Deritative gain for limiter in charge	Elpwrlim Charge Limiter Derivative Gain
21	ElpwrlimChLimrDervMax	single	[1,1]	Min: , Max:		Maximum relative derivative contribution in charge	Elpwrlim Charge Limiter Derivative Maximum
22	ElpwrlimChLimrIntglGainDec	single	[1,1]	Min: , Max:		Integral gain for limiter in charge (decrease)	Elpwrlim Charge Limiter Integral Gain Decrease
23	ElpwrlimChLimrIntglGainInc	single	[1,1]	Min: , Max:		Integral gain for limiter in charge (increase)	Elpwrlim Charge Limiter Integral Gain Increase
24	ElpwrlimChPropIntglCtlMarg	single	[1,1]	Min: , Max:		Margin for activating PI contribution in charge	Elpwrlim Charge Proportional Integral Control Margin
25	ElpwrlimChTqLoss	single	[1,6]	Min: , Max:	N*m	Torque loss map in charge scenario	Elpwrlim Charge Torque Loss
26	ElpwrlimDchaLimrIntglGainDec	single	[1,1]	Min: , Max:		Integral gain for limiter in discharge (decrease)	Elpwrlim Discharge Limiter Integral Gain Decrease
27	ElpwrlimDchaLimrIntglGainInc	single	[1,1]	Min: , Max:		Integral gain for limiter in discharge (increase)	Elpwrlim Discharge Limiter Integral Gain Increase
28	ElpwrlimDchaTqLoss	single	[1,6]	Min: , Max:	N*m	Torque loss map in discharge scenario	Elpwrlim Discharge Torque Loss
29	ElpwrlimHvPwrActGain	single	[1,1]	Min: , Max:	1	Hv istantaneous correction factor	Elpwrlim Hv Power Actual Gain
30	ElpwrlimHvPwrSeln	boolean	[1,1]	Min: , Max:		Electrical Instantaneous power selection: 0-Mechanical power estimated by inverters;1 - Actual Istantaneours Power from HV.	Elpwrlim Hv Power Selection
31	ElpwrlimSpdAvrgFil	single	[1,1]	Min: , Max:	Hz	Motor speed filter frequency	Elpwrlim Speed Average Filter
32	ElpwrlimSpdAvrgSeln	uint8	[1,1]	Min: , Max:		Select type of motor speed averaging - 1 is torque distribution, 2 is normal average, 3 is maximum motor speed	Elpwrlim Speed Average Selection
33	ElpwrlimTotTqMaxSatn	single	[1,1]	Min: 0, Max: 20000	N*m	Electrical power limitation - max Total torque saturation (Traction)	Elpwrlim Total Torque Maximum Saturation
34	ElpwrlimTotTqMinSatn	single	[1,1]	Min: -20000, Max: 0	N*m	Electrical power limitation - min Total torque saturation (Regen)	Elpwrlim Total Torque Minimum Saturation
35	ElpwrlimTqLossBrkPnt	single	[1,6]	Min: , Max:	km/h	BreakPoints speed vector for Torque loss map	Elpwrlim Torque Loss Brake Point

4.9.5. Calibration

EltPwrLim must be set up according to the specifications of the HV system being used. Charging scenario is considered when the vehicle is in regeneration, whereas Discharging refers to when the vehicle is in traction condition. Calibration of the parameters must be in line with the sampling time selected for the specific software module.

4.9.5.1. Step 1 - Configure Electric Power Limits for Discharge/Charge condition

Select static Battery power discharge limit EltPwrLimBatPwrDchaSeln for 30Sec (0), 10Sec (1) or 2Sec (3). Default is 30Sec.
Provide ElpwrlimBatPwrDchaMax as maximum allowable Battery discharge power, e.g. 600000W to be considered in case BMS value is not broadcasted.
Adjust Offset EltPwrLimBatPwrDchaOfs to be applied to the limit considered in order to compensate for any rounding errors - it can be null if not needed.
Select ElpwrlimBatPwrDchaGain (<1) as the safety factor for the battery limit selected via EltPwrLimBatPwrDchaSeln in order to work always below the desired limit. This can be 0.97 as an example.
Select a cut-off frequency ElpwrlimBatPwrDchaFil to filter-out unwanted oscillation for the value. Default is 1Hz.

Apply the same steps for the following parameters:
EltPwrLimBatPwrChaSeln ,
ElpwrlimBatPwrChMin ,
EltPwrLimBatPwrChaOfs ,
EltPwrLimBatPwrChaGain ,
ElpwrlimBatPwrChFil for Charging scenarios.

4.9.5.2. Step 2 - Select source for Powertrain consumption

Set ElpwrlimHvPwrSeln to true if feedback from BMS power consumption is desired. Set it to false if instantaneous mechanical power from the electric motors feedback is preferred. If the latter is selected, ElpwrlimSpdAvrgFil can be used to select the cut-off frequency for the first order filter. 2Hz is the default.
If feedback from BMS is preferred, ElpwrlimHvPwrActGain can be used to adjust the sign convention for BMS power consumption feedback, if needed.

4.9.5.3. Step 3 - Configure Battery Power to Motor Torque limit

The limit controller is of I+D+ anti-windup form, which adjusts the wheel torque limits in order to avoid exceeding the battery power limits. Distinct parameters can be tuned in order to achieve the desired performances. In the following, the Charge case is provided.
ElpwrlimChLimrIntglGainInc governs the integral error for increments; ElpwrlimChLimrIntglGainDec governs the integral error for decrements. These two contributions are added together with the anti-windup ElpwrlimAntiWndpGain contributions. D-term contribution kicks-in once the actual power consumption for the drivetrain is close to ElpwrlimChDervCtlMarg, which represents the threshold of activation of the derivative term.
Lastly, ElpwrlimChLimrDervDcyRate specifies the dynamic rate changes to filter out the control action.
Similar control schematic is used for Discharge scenarios. Tuning parameters are: ElpwrlimDchaLimrIntglGainInc; ElpwrlimDchaLimrIntglGainDec;ElpwrlimAntiWndpGain;ElpwrlimDchaDervCtlMarg;ElpwrlimDchaLimrDervDcyRate.

4.9.5.4. Notes

None