KR100514372B1 - Method of controlling auxiliary power unit in a series hybrid electric bus - Google Patents

Abstract

A method of controlling an auxiliary power unit for a tandem hybrid bus is disclosed. The disclosed method for controlling an auxiliary power unit for a serial hybrid bus includes: inputting information required for a vehicle controller of a serial hybrid bus and generating a driving torque (TM) of the serial hybrid bus motor; Inputting a rotational speed (ωM) signal of the electric motor and a required power reference value (PVEH) signal to the vehicle controller, and determining whether the battery charge state SOC is smaller than its lower limit SOClow_limit; When the state of charge of the battery is smaller than the lower limit value, the auxiliary power request amount PAPU required from the engine and the generator of the series hybrid bus is set to the maximum power value PAPU_max, and the state of the auxiliary power unit is in a transient state. Determining; If the state of the auxiliary power unit is not in a transient state, the torque τ of the series hybrid bus engine and the speed of the generator ω are input to the controller of the auxiliary power unit in the table data, and the engine torque ( τENG) and a speed ωG of the generator; Outputting the torque of the engine and sending it to an engine control unit (ECU) of the serial hybrid bus, outputting the speed of the generator and sending it to a generator controller (GCU).

According to the present invention, it is possible to reduce the fuel consumption rate and nitrogen oxide emissions, there is an advantage that can be operated to a high efficiency point in each of the engine and generator.

Description

Auxiliary Power Unit Control Method for Serial Hybrid Bus {METHOD OF CONTROLLING AUXILIARY POWER UNIT IN A SERIES HYBRID ELECTRIC BUS}

The present invention relates to a method for controlling an auxiliary power unit for a tandem hybrid bus, and more particularly, to a method for controlling an auxiliary power unit for a tandem hybrid bus to obtain characteristics of low pollution and high fuel consumption.

Recently, the automobile technology is focused on the development of low pollution and high fuel consumption vehicles due to the problem of global environment and exhaustion of petroleum resources, and the development of power system that can replace the existing internal combustion engine such as hybrid electric vehicles, fuel cell vehicles, and electric vehicles. Interest is growing.

In particular, hybrid electric vehicles are attracting attention as more realistic alternatives than electric vehicles and fuel cell vehicles, which are limited in mileage, cost, vehicle performance, and technical maturity. Such a hybrid electric vehicle has a power transmission device driven by mounting an internal combustion engine and an electric motor at the same time, and is classified into a series type and a parallel type according to a driving method.

The parallel type is combined in parallel so that the power from the internal combustion engine and the electric motor meets the required power of the vehicle, and the series type only the electric motor drives the vehicle, and the internal combustion engine converts the fuel into electric power. Play a role.

On the other hand, in a large city such as Seoul, low-pollution, high fuel-efficient public transportation is required. For this purpose, Hyundai Motor Company, which is the applicant of the present application, uses a series hybrid bus vehicle composed of a 1.5L diesel engine, an induction motor, a generator, and a lead acid battery. Developed.

The most important thing in controlling the above-mentioned series hybrid bus is to efficiently maintain the state of charge of the battery (SOC), and the auxiliary power unit (APU) composed of the internal combustion engine and the generator can efficiently generate the required power for driving the vehicle. To make it possible.

As shown in FIG. 1, the series hybrid bus is composed of three main parts: an electric power unit 10, an electric energy storage device 20, and an electric energy generator 30.

The electric power unit 10 is composed of a 120kW induction motor, an electric motor controller (MCU), and a first gear reduction gear. In addition, a lead-acid battery pack is used as the electric energy storage device 20, and serves as an energy buffer between the electric power unit 10 and the electric energy generator 30.

The electric energy generating device 30 denoted as an auxiliary power unit in FIG. 1 is a 1.5L common rail fuel injection type diesel engine and an engine control unit (ECU), an induction generator of 30 kW and the generator controller (GCU). )

And the rotor of the induction generator is connected to the crankshaft of the engine through a damper plate to mitigate the ripple of the engine torque. Regarding the driver's will, such as the state of charge of the battery (SOC), the accelerator pedal amount, the brake pedal amount and the shift lever position, the vehicle controller (HVCU) 40, which is the upper controller of the hybrid bus, is connected to the auxiliary power unit controller and the motor controller. Generate a command.

The command to the motor controller is a torque command sent to the motor to determine the acceleration or deceleration of the vehicle, and the command to the motor controller is directed to the motor and the battery to maintain the state of charge of the battery under the current driving conditions of the vehicle. Power command sent.

In addition, in order for the auxiliary power unit to generate the power required from the vehicle controller 40, the speed and torque of the engine must be determined. The auxiliary power unit controller is configured to provide the torque command value and the speed command value to the engine control unit and the generator controller, respectively. Make up. At a given speed, the engine torque can be determined and controlled by the fuel volume.

The engine speed is determined and controlled by the speed control of the generator and the generator controller. The generator controlled at a constant speed by the generator controller automatically generates (-) torque of the same size as the engine torque. Therefore, it is possible to generate the same power as the power required from the vehicle controller 40 with the torque and speed determined by the auxiliary power unit.

As a conventional technique as described above, Japanese Patent Publication No. 1997-093715 (hereinafter referred to as First Conventional Technology), Japanese Patent Publication No. 1997-009412 (hereinafter referred to as Second Conventional Technology), and Korean Patent Publication No. 1999-17621 (hereinafter referred to as Japanese Patent Publication No. 1997-093715 , Japanese Patent Application Publication No. 1997-093716 (hereinafter referred to as Japanese Patent Application Publication No. 4), and the like.

The above-described first conventional technology is characterized in that the overall efficiency is low when the charging rate is poor, for example, when the battery temperature is low or the rise of the battery charge rate is low for other reasons, or when the actual output is low so that the output is not lowered by the generator operating state detection method. There may be more fuel consumption without consideration.

In the second conventional technique, the speed control at the selected engine speed or the detection of the operation area with high power generation efficiency is similar to the present invention described later, but the same as in the case of the on / off control. The generation is large, and the cost of the NOx reduction sensor rises.

This suggests a movement to a driving point with similar efficiency, but there is no mention of the movement path, and in practice, many paths need to be moved along the x-axis or y-axis for noise reduction. It violates prerequisites that should be similar. In addition, the noise in the actual test set and the vehicle should be considered at the same speed, not just the driving speed, so if the purpose of moving the driving point to consider the noise is to sacrifice the overall power output reduction. It must be followed. In other words, it is difficult to satisfy the desired output in the same noise and similar efficiency range.

In addition, the third conventional technology is to supply a certain amount of power, which is the maximum efficiency to the load through voltage and current control, which is currently only a commonly used algorithm.

The fourth conventional technology is currently being used as an algorithm for controlling the amount of power generated by excluding the battery burden from the required driving power. There is also a possibility that the driving point of the speed is too diverse, causing problems due to the difference in the dynamics of the engine and the motor.

The present invention was created in order to solve the above problems, and has a reduction in fuel consumption rate and nitrogen oxide emission, and controls the auxiliary power unit for the series hybrid bus which enables operation to a high efficiency point in each of the engine and the generator. The purpose is to provide a method.

In order to achieve the above object, a method for controlling an auxiliary power unit for a serial hybrid bus according to the present invention includes inputting necessary information to a vehicle controller of a serial hybrid bus and adjusting the driving torque (TM) of the serial hybrid bus motor. Generating; Inputting a rotational speed (ωM) signal of the electric motor and a required power reference value (PVEH) signal to the vehicle controller, and determining whether the battery charge state SOC is smaller than its lower limit SOClow_limit; When the state of charge of the battery is smaller than the lower limit value, the auxiliary power request amount PAPU required from the engine and the generator of the series hybrid bus is set to the maximum power value PAPU_max, and the state of the auxiliary power unit is in a transient state. Determining; If the state of the auxiliary power unit is not in a transient state, the torque τ of the series hybrid bus engine and the speed of the generator ω are input to the controller of the auxiliary power unit in the table data, and the engine torque ( τENG) and a speed ωG of the generator; Outputting the torque of the engine and sending it to an engine control unit (ECU) of the serial hybrid bus, outputting the speed of the generator and sending it to a generator controller (GCU).

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, before describing a method for controlling an auxiliary power unit for a serial hybrid bus according to the present invention, a system to which the method according to the present invention is applied will be described.

Figure 2 schematically shows a series hybrid bus (or vehicle) control system to which the auxiliary power control method for a serial hybrid bus according to the present invention is applied.

As shown, the motor controller (MCU) 51 drives the drive torque TM and the rotational speed ωM of the motor 53 to be sent to the vehicle controller HVCU 52 in relation to the driver's will, such as acceleration and deceleration. The power reference value Pveh is required while generating the value. The vehicle controller 52 also receives information on the state of charge of the battery (SOC) and instructs the controller (APU) 61 of the APU system 60 to generate the power demand PAPU. .

With reference to the control system as described above will be described in the control method for the auxiliary power unit for a serial hybrid bus according to the present invention.

FIG. 3 is a schematic flowchart showing a method of controlling an auxiliary power unit for a serial hybrid bus according to the present invention in sequence.

Referring to the drawings, the control method of the auxiliary power unit for the serial hybrid bus according to the present invention, first, to the vehicle controller 52 of the serial hybrid bus (Accc.) And brake (Brake) signal and the state of charge of the battery ( SOC) information (steps 110, 120).

Subsequently, a driving torque TM of the series hybrid bus motor 53 is generated (step 130).

Then, the rotational speed ωM signal and the required power reference value PVEH signal of the electric motor 53 are input to the vehicle controller 52 (steps 140 and 150).

It is also determined whether the battery charge state SOC of the serial hybrid bus is smaller than its lower limit SOClow_limit (step 160).

If the condition in step 160 is satisfied, i.e., the battery state of charge (SOC) is less than its lower limit (SOClow_limit), it is required from the engine (ENG) 62 and the generator (G) 63 of the series hybrid bus. The auxiliary power request amount PAPU is set to the maximum power value PAPU_max (step 170).

Next, it is determined whether the state of the auxiliary power unit 60 is a transient state (step 180).

If the condition in step 180 is not satisfied, i.e., if it is not a transient state, the torque of the in-line hybrid bus engine 62 in the table Efficient Look-up data 66 in the auxiliary power unit controller 61; τ and the speed ω of the generator 63 are input, and the torque τENG of the engine 62 and the speed ωG of the generator 63 are generated (generated). (steps 190, 200)

And outputs the torque of the engine 62 and sends it to the engine control unit (ECU) 64 of the serial hybrid bus, outputs the speed of the generator 63 and sends it to the generator controller (GCU) 65. (Steps 210,220)

On the other hand, if the condition in step 160 is not satisfied, that is, the battery state of charge (SOC) is not less than the lower limit SOClow_limit, it is determined whether the battery state of charge (SOC) is greater than the upper limit value (SOChigh_limit). )

Subsequently, when the condition in step 310 is satisfied, that is, when the battery state of charge SOC is greater than the upper limit value SOChigh_limit, the power demand amount PAPU is set to the minimum power value PAPU_min, and then the step 180 is performed. (Step 320)

When the condition at step 310 is not satisfied, that is, when the battery state of charge SOC is not greater than the upper limit SOChigh_limit, it is determined whether the required power reference value PVEH is smaller than the lower limit value Popt_low. Step 410)

If the condition in step 410 is not satisfied, that is, the demand power reference value PVEH is not smaller than the lower limit value Popt_low, it is determined whether the demand power reference value PVEH is larger than the upper limit value Popt_high (step 420). )

If the condition at step 420 is not satisfied, that is, if the required power reference value PVEH is not greater than the upper limit value Popt_high, the auxiliary power demand PAPU is set to 15 kW, and the step 180 is then performed. (Step 430)

Subsequently, if the condition in step 410 is satisfied, the auxiliary power demand (PAPU) is set to 30 kW, and then step 180 is performed (step 440).

If the condition in step 420 is satisfied, the auxiliary power request amount PAPU is set to 10 kW, and step 180 is then performed.

On the other hand, when the condition in step 180 is satisfied, that is, when it is determined that the transient state is satisfied, the torque change amount Δτ ENG of the engine 62 and the speed change amount Δω G of the generator 63 are generated. )

Referring to the auxiliary power control method for a serial hybrid bus according to the present invention made as described above in more detail.

In the method of controlling an auxiliary power unit for a tandem hybrid bus according to the present invention, the diesel engine 62 is in a torque control mode for a power system applied to the tandem hybrid bus based on the characteristic data analysis result of the engine 62. 63) is made by establishing a system control strategy of the auxiliary power unit 60 operating in the speed control mode, and performing a simulation according to the operation cycle to verify the validity of the control strategy.

The most important in controlling the SHEB is a power unit control, battery charge state (SOC) management, control of the auxiliary power unit 60, in the present invention, the auxiliary power unit for supplying the power required for the motor The control of 60 was focused on.

In the control of the auxiliary power unit 60, first, the auxiliary power unit controller 61 generates a power command value in consideration of the driver's intention such as the state of charge of the battery (SOC), the vehicle speed, the brake and the accelerator pedal amount, and the like. In order to generate electrical energy, the speed command value in the generator controller 65, the torque command value generation in the engine control device 64, and the movement of the power command value in the transient state (speed, torque curve consideration) and the like.

First, generation of the power command value PAPU is one of the main roles of the auxiliary power unit controller 61. As shown in FIG. 4, any value among the isopower curves on the speed-torque (ω-τ) plane is shown. Whether or not it is selected.

In the present invention, the required power of the vehicle controller 52 is determined according to the control strategy shown in TABLE 1 of FIG. That is, when the state of charge of the battery SOC is smaller than the lower limit SOClow_limit, the auxiliary power unit 60 commands the maximum power value PAPU_max. . When the battery charge state SOC is between the lower limit value and the upper limit value, the PAPU is generated in consideration of the SOC and the vehicle demand force Pveh at the same time.

Next, generation of the speed and torque command values will be described.

Optimal operation of the auxiliary power unit 60 is possible by adjusting the speed and torque of the engine 62 and the generator 63. After the power command value is determined, the auxiliary power unit controller 61 generates a speed command value to the generator 63 and a torque command value to the engine 62.

However, even if the same power is generated, it is very important to determine the optimum speed and torque because the exhaust gas and fuel consumption rate are different depending on the combination of speed and torque. The torque generated in the diesel engine 62 is controlled by the fuel injection amount, and the relationship between the torque and the fuel injection amount can be obtained from an experiment using a dynamometer, and stored in the memory of the controller in the form of a map as shown in FIG. Can be. Also, based on this data, the torque command value can be converted into the fuel injection amount command value.

In addition, the command value movement in the present invention, as shown in Figures 7 and 8, is defined as the change trajectory of the speed and torque when the operating point of the auxiliary power unit 60 moves from P1 to P2. In general, it takes several seconds or more due to the limitation of the dynamic characteristics of the engine 62 to stabilize the steady state by moving the operating point. And since the operating state of the series hybrid bus (vehicle) (SHEV) is often changed according to the load conditions, it is difficult for the auxiliary power unit 60 to remain in a steady state for a sufficient time.

Therefore, consideration should be given to system efficiency and emissions characteristics under transient conditions. The efficiency and exhaust gas characteristics of the auxiliary power unit 60 depend on the selection of an optimal combination of speed and torque through a trial and error method by a vehicle driving test.

In the present invention, the speed and torque command values in the transient state are selected as follows.

First, the torque command value increases and decreases linearly with less mechanical impact. The speed command value is linearly increased and decreased while suppressing overshoot or undershoot of the speed.

And the speed control of the generator 63 is demonstrated.

The specification of the generator 63 is shown in Table 2 of FIG. The generator 63 uses water cooling in consideration of the size of the storage space and the cooling efficiency, and the insulation between the windings and the winding-frames is reinforced in preparation for di / dt and dv / dt due to the high-speed switching of the inverter controller 65 inverter. It was made.

10 is a block diagram for speed control of the induction generator 63. The error between the reference speed and the actual speed is input to the proportional integral (PI) speed controller. The output of the proportional integral speed controller is used as the q-axis reference current value that generates the torque of the generator 63.

The proportional integral type current controller may be regarded as a low pass filter as shown in FIG. 10 because the dynamic response is faster than that of the speed controller.

Next, the simulation of the control strategy of the serial hybrid bus (vehicle) in the present invention will be described.

According to the current state of charge (SOC) of the vehicle and the required power of the vehicle, the auxiliary power required from the engine 62 to the generator 63 is 10kW and 15kW as shown in Table 1 of FIG. 5 in consideration of the power efficiency of the generator 63. Power based on vehicle operation by dividing it into a serial hybrid bus (vehicle) control strategy subdivided into 20kW and a thermostat control strategy to supply power repeatedly on and off at 0kW and 20kW. Simulations were performed on the supply, the state of charge of the battery, the emissions of the engine 62 and the output characteristics of the generator 63, and the results were compared.

In determining the torque command and the speed command according to the determined power demand, the engine 62 is set to operate in the region having the best efficiency in consideration of the power efficiency of the generator 63 shown in FIG. The most efficient area from the power efficiency data of the generator 63 corresponds to the speed of the engine 62 in the range of 2200 to 2700 rpm. However, in the control strategy proposed in the present invention, the speed of the generator 63 is kept constant at 2400 rpm. (62) The torque was changed to 40Nm, 60Nm and 80Nm, respectively, to generate power corresponding to the auxiliary power requirement.

Simulation was performed for the initial 600 sec in the FTP-75 mode. FIG. 12 shows the vehicle speed and the required power Pveh over time.

12 shows the required power of the battery calculated in the auxiliary power demand PAPU and the battery management system BMS 70 required from the engine 62-generator 63. As a result, as the vehicle frequently accelerates and decelerates, and thus the power demand of the vehicle changes rapidly, the change in the power requirement required for the auxiliary power unit in the thermostat control strategy changes the serial hybrid bus (vehicle) ( It can be seen that it changes more rapidly than the case by the control strategy. Both control strategies provide a stable supply of power to the vehicle within 0.005 kW of power tolerance.

13 is a simulation comparison of fuel injection, battery charge (SOC) change, and emission characteristics between a series hybrid bus (SHEV) control and a thermostat control strategy by simulation in FTP-75 mode. The result is.

The results of the above-described serial hybrid bus (vehicle) control strategy are dimensionless based on the thermostat results. As shown in the results, the proposed tandem hybrid bus (vehicle) control strategy is superior to the thermostat strategy in fuel consumption and NOx, but the effect is low in HC and CO emissions.

When driving a vehicle by a serial hybrid bus (vehicle) control strategy, the amount of power to be supplied from the auxiliary power unit is subdivided according to the required power of the vehicle, and the appropriate driving speed of the engine 62 as well as the torque according to each driving situation. Considering these factors, it is expected that the driving target of the vehicle, such as fuel efficiency improvement and emission reduction, can be more effectively achieved.

As described above, according to the present invention, the power command value generation of the auxiliary power unit controller 61 and the torque and speed command value generation of the engine control unit 64 and the generator controller 65 are generated for the power system applied to the series hybrid bus. And control strategies such as command value movement in transient state and speed control of vector control induction generator (63) were investigated and analyzed.

And the control algorithm of the auxiliary power unit 60 based on the above strategy was confirmed through modeling and simulation using the FTP-75 driving mode. We developed a series hybrid bus (vehicle) control strategy that subdivides the auxiliary power requirement from the engine 62-generator 63 in consideration of the battery charging status and the required power of the vehicle in consideration of the power efficiency of the generator 63. In comparison with the on / off thermostat control strategy, it was found to be effective in reducing fuel consumption and NOx emissions.

As described above, the control method of the auxiliary power unit for the serial hybrid bus according to the present invention has the following effects.

Independent control of the traction motor drive unit and the auxiliary power unit control unit is possible, and the vehicle can be driven even in the event of a fault of the auxiliary power unit controller.

And by using the map data from the preliminary experiments, it is possible to drive to a high efficiency point in each of the engine and generator.

In addition, fuel consumption and nitrogen oxide emissions can be reduced.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent embodiments are possible. Therefore, the true scope of protection of the present invention should be defined only by the appended claims.

1 is a view schematically showing a system configuration of a serial hybrid bus according to the prior art.

2 is a view schematically showing a system configuration to which the auxiliary power control method for a tandem hybrid bus according to the present invention is applied.

Figure 3 is a schematic flow chart showing sequentially a control method of the auxiliary power unit for a serial hybrid bus according to the present invention.

4 shows an isopower curve on the velocity-torque (ω-τ) plane.

5 is a table 1 showing the amount of power required by the motor controller and the vehicle controller.

6 is a graph showing the relationship between torque, speed, and fuel injection amount in a diesel engine.

7 and 8 are graphs showing changes in speed and torque in the auxiliary power unit.

9 is a table showing the specifications of the generator.

10 is a block diagram showing the speed control of the induction generator.

11 is a graph showing the power efficiency of the generator.

12 is a graph showing vehicle speed and required power of a vehicle with time;

FIG. 13 is a simulation comparison of fuel injection amount, battery state of charge (SOC), and emission characteristics between a series hybrid bus (SHEV) control strategy and a thermostat control strategy. graph.

<Description of the symbols for the main parts of the drawings>

51. Motor controller 52. Vehicle controller

53. Electric motor 60. Auxiliary power unit

61. Auxiliary Power Supply Controller 62. Engine

63. Generator 64. Engine Control

65. Generator Controller

Claims (6)

Inputting information required for the vehicle controller of the series hybrid bus and generating a driving torque (TM) of the series hybrid bus motor; Inputting a rotational speed (ωM) signal of the electric motor and a required power reference value (PVEH) signal to the vehicle controller, and determining whether the battery charge state SOC is smaller than its lower limit SOClow_limit; When the state of charge of the battery is smaller than the lower limit value, the auxiliary power request amount PAPU required from the engine and the generator of the series hybrid bus is set to the maximum power value PAPU_max, and the state of the auxiliary power unit is in a transient state. Determining; If the state of the auxiliary power unit is not in a transient state, the torque τ of the series hybrid bus engine and the speed of the generator ω are input to the controller of the auxiliary power unit in the table data, and the engine torque ( τENG) and a speed ωG of the generator; Outputting the torque of the engine and sending it to an engine control unit (ECU) of the tandem hybrid bus, outputting the speed of the generator and sending it to the generator controller (GCU). Control method of auxiliary power unit for bus. The method of claim 1, When the state of charge of the battery is not smaller than the lower limit value, the battery state of charge SOC is determined to be greater than the upper limit value SOChigh_limit, and when it is satisfied, the power request amount PAPU is set to the minimum power value PAPU_min. And continuing from the step of determining whether the state of the auxiliary power unit is in a transient state. The method of claim 2, If the battery state of charge SOC is greater than the upper limit value SOChigh_limit and is not satisfied, the request power reference value PVEH is less than the lower limit value Popt_low. Determining whether the power reference value PVEH is greater than its upper limit value Popt_high; If it is determined that the required power reference value PVEH is larger than its upper limit value Popt_high, and it is not satisfied, the auxiliary power demand PAPU is set to 15 kW, and it is continued whether the state of the auxiliary power device is transient. And re-performing from the determining step. The method of controlling an auxiliary power unit for a serial hybrid bus, the method comprising: a. The method of claim 3, If it is determined that the required power reference value PVEH is smaller than its upper limit value Popt_high, and it is satisfied, the auxiliary power demand PAPU is set to 30 kW, and it is subsequently determined whether the state of the auxiliary power device is transient. The auxiliary motor control method for a serial hybrid bus, characterized in that for performing again from the step. The method of claim 3, If it is determined that the required power reference value PVEH is greater than its upper limit value Popt_high, and if it is satisfied, the auxiliary power request amount PAPU is set to 10 kW, and it is subsequently determined whether the state of the auxiliary power device is transient. A method for controlling an auxiliary power unit for a serial hybrid bus, characterized in that the step is performed again. The method of claim 1, When it is determined that the state of the auxiliary power unit is a transient state and satisfies this, the auxiliary power unit for the series hybrid bus, characterized in that to generate the torque change amount (ΔτENG) of the engine and the speed change amount (ΔωG) of the generator. Control method.