KR101157413B1 - Series hybrid electric vehicle and method for controlling power of the same - Google Patents

Abstract

PURPOSE: A series hybrid electric vehicle is provided to reduce duty cycle of a battery by equipping with an ultra capacitor. CONSTITUTION: A power controlling method of a series hybrid electric vehicle which has an engine, generator, battery, and an ultra capacitor as an energy source comprises; a step(S110) of determining whether the engine and the generator operates or not based on charged state of the battery; a step(S120) of calculating required power of the engine and the battery based on necessary power for operating a motor, a first compensating power to the charged state of the battery, and a second compensating power to the charged state of the ultra capacitor; a step(S150) of calculating a third compensating powder by the battery compensating for the ultra capacitor; and a step of distributing the necessary power based on whether the engine and the generator operates or not.

Description

SERIES HYBRID ELECTRIC VEHICLE AND METHOD FOR CONTROLLING POWER OF THE SAME

The present invention relates to a series hybrid vehicle having an ultracapacitor and a power control method thereof.

Hybrid vehicles are classified into a series hybrid vehicle and a parallel hybrid vehicle. In-line hybrid vehicles use only an electric motor to move the vehicle, and the engine is mainly used to charge the battery. Therefore, fuel economy is excellent. Since in-line hybrid vehicles are driven mainly by electric motors, the engine uses a lot of low-power engines.

Parallel hybrid vehicles start the engine through an electric motor at start-up, minimizing fuel consumption during start-up and minimizing engine emissions. In addition, in the parallel type, when the vehicle is accelerated, the motor driven by the battery during the constant speed assists the engine power. In other words, the car is designed to move at low speed, and when driving the vehicle, an engine using gasoline or diesel as fuel is used in a section where the lowest fuel economy is achieved when a certain speed is exceeded. In addition, during braking, the driving motor becomes a generator to recover operating energy.

Looking at the higher-level control algorithms of conventional tandem hybrid vehicles, most of them focus on power distribution between the engine / generator and the battery. In this case, the battery usage rate is high, which reduces the battery life. Ultracapacitors, one of the energy storage devices, can be used to mitigate battery load discharge and charge, thereby avoiding rapid current changes, resulting in reduced battery utilization and longer lifespan.

Embodiments of the present invention have an object of providing a series hybrid vehicle and a power control method thereof having an ultra capacitor to reduce the battery usage.

Embodiments of the present invention provide an in-line hybrid vehicle having an engine, a generator, a battery, and an ultracapacitor as an energy source. The present invention provides a series hybrid vehicle and a power control method thereof, in which the ultracapacitor covers a high frequency region of power required. There is another purpose.

Embodiments of the present invention, in consideration of the state of charge of the ultracapacitor, when the ultracapacitor is used as an energy source together with the engine, the generator, and the battery, a series hybrid vehicle and its power control to improve the use efficiency of the ultracapacitor Another purpose is to provide a method.

In a power control method of a series hybrid vehicle according to an embodiment, the power control method of a series hybrid vehicle having an engine, a generator, a battery, and an ultracapacitor as an energy source, the engine based on the state of charge of the battery And determining whether to operate the generator, calculating the required power of the engine and the generator based on the operation of the engine and the generator, and calculating the compensation power compensated by the battery through the ultracapacitor of the required power. And distributing the required power based on whether the engine and the generator are in operation, wherein the required power is an optimal operating point having the best efficiency of the engine and the generator during operation of the engine and the generator. It is characterized in that the power at.

In another embodiment, a power control method of a series hybrid vehicle includes an engine, a generator, a battery, and an ultracapacitor as an energy source. The method of controlling power of the series hybrid vehicle is based on a state of charge of the battery. And determining whether to operate the generator, the required power of the engine and the generator based on the required power, the first compensation power for the state of charge of the battery, and the second compensation power for the state of charge of the ultracapacitor. And calculating a third compensation power compensated by the battery with the ultracapacitor, and distributing the required power based on whether the engine and the generator are operated.

In another embodiment, a power control method of a series hybrid vehicle includes an engine and a generator, a battery, and an ultracapacitor as an energy source, and the power control method of the series hybrid vehicle provides power. Calculating output power to be output by the battery and the ultracapacitor according to the required power of the power supply; dividing the output power by the required power of the battery and the required power of the ultracapacitor; Calculating power and distributing the required power to each energy source using the calculated power requirements of the engine and generator.

An in-line hybrid vehicle according to an embodiment includes an engine and a generator driven by the engine, a converter for converting a required power of the generator into first DC power, a battery supplying a second DC power, an ultracapacitor, DC-DC converter for converting the output power of the ultra-capacitor into a third DC power, a smoothing unit connected in parallel to the converter and DC-DC converter, an inverter connected to the smoothing unit, and supplies the necessary power to the motor And a control unit for distributing the required power to the engine and generator, battery, and ultracapacitor. Here, the control unit is characterized in that the high-frequency region of the portion except the required power of the engine and the generator of the required power to the ultra-capacitor to bear, the low-frequency region to the battery.

A series hybrid vehicle and a power control method thereof according to embodiments of the present invention may include an ultracapacitor to reduce battery usage. Embodiments of the present invention are an in-line hybrid vehicle having an engine, a generator, a battery, and an ultracapacitor as an energy source, so that the ultracapacitor can cover a high frequency region of power required, thereby increasing the life of the battery.

Embodiments of the present invention improve the use efficiency of ultracapacitors when the ultracapacitor is used as an energy source together with an engine, a generator, and a battery in consideration of the state of charge of the ultracapacitor.

Embodiments of the present invention are an upper control algorithm of a series hybrid vehicle equipped with an engine, a generator, a battery, and an ultracapacitor as an energy source, thereby performing efficient power distribution and increasing fuel economy.

1 is a diagram illustrating a target state of charge (Target SOC) of an ultracapacitor according to a speed of a vehicle in a series hybrid vehicle according to embodiments of the present disclosure;
2 is a view illustrating a condition for determining an operation of an engine in a power control method of a series hybrid vehicle according to an embodiment of the present disclosure;
3 is a view illustrating a condition for determining an operation of an engine in a method of controlling power of a series hybrid vehicle according to another embodiment;
4 is a view for explaining an operation for preventing the operating point of the engine and the generator from changing quickly in the power control method of a series hybrid vehicle according to another embodiment, the battery charge state tracking error (k _{bat . SOC} ) Showing engine operating point holding time (T _a ) as _a function of the absolute value of;
5 is in the power control of a series-type hybrid vehicle in the process according to another embodiment, the standing engine and road for illustrating an operation for preventing the operating point is fast changing of the generator, the engine and generator modify the requested electric power (P _{e / g2 Showing the} required power change limiting power P _{delta as} a function of
6 is a diagram illustrating a modeling configuration of a battery and an ultra capacitor in a power control method of a series hybrid vehicle according to still another embodiment;
7 is also in the power control of a series-type hybrid vehicle in the process according to another embodiment, the road on, ultracapacitor charge tracking errors (k _ucap for illustrating an operation for managing and maintaining the state of charge of the _{ultracapacitor. SOC Shows} a weight (S _ucap ) according to;
FIG. 8 is a view illustrating an operation for managing and maintaining a state of charge of a battery in a method of controlling power of a series hybrid vehicle according to another embodiment, and showing a weight S _bat according to a state of charge of a battery. Degree;
9 is a flowchart schematically illustrating a power control method of a series hybrid vehicle according to an exemplary embodiment;
10 is a flowchart schematically illustrating a power control method of a series hybrid vehicle according to another embodiment;
11 is a flowchart schematically illustrating a power control method of a series hybrid vehicle according to another embodiment; And
12 is a block diagram schematically illustrating a configuration of a series hybrid vehicle according to embodiments of the present invention.

First, referring to FIG. 12, in a series hybrid vehicle according to embodiments of the present invention, an engine 1, a generator 2 driven by the engine 1, and a required power of the generator 2 may be provided. A converter 3 for converting to DC power, a battery 4 for supplying a second DC power, and a DC-DC for converting the ultra capacitor 5 and the output power of the ultra capacitor 5 to a third DC power. Converter 6, a smoothing unit 7 connected in parallel to the converter 3 and a DC-DC converter 6, and an inverter 8 connected to the smoothing unit 7 and supplying necessary power to a motor. And a control unit (not shown) for distributing the required power to the engine and generator, battery, and ultracapacitor.

Here, the control unit, the high-frequency region of the portion except the required power of the engine 1 and the generator 2 of the required power so that the ultra-capacitor (5) can afford, the low-frequency region is the battery (4) ) To bear.

The series hybrid vehicle further includes a first sensor detecting a charging state of the battery 4 and a second sensor detecting a charging state of the ultracapacitor 5.

In one embodiment, the control unit operates the engine 1 and the generator 2 based on the state of charge of the battery 4 and calculates the required power. When the engine 1 and the generator 2 operate, the required power of the engine and the generator is the power at the optimum operating point with the best efficiency of the engine and the generator.

Referring to FIG. 9, a power control method of a series hybrid vehicle according to an embodiment includes an engine, a generator, a battery, and an ultracapacitor as energy sources. The power control method of the series hybrid vehicle may include determining whether to operate the engine and the generator based on the state of charge of the battery (S110), and based on whether the engine and the generator are operated. Calculating the required power (S120, S130), calculating a compensation power compensated by the battery of the ultra-capacitor among the required power (S140), and calculating the required power based on whether the engine and the generator are operated. Dispensing step (S150) is configured. Here, the required power is characterized in that the power at the optimum operating point, the efficiency of the engine and the generator is the best when the engine and the generator operating. Of course, the power demand is zero when the engine and generator are not operating.

The power control method according to an embodiment relates to a thermostat (TS) control method. That is, the power control method according to an embodiment operates the engine and the generator only at an optimal operating point (OOP), which is the most efficient point, and the engine according to the state of charge (SOC) of the battery. And a method of determining whether the generator is operating. Here, the optimum operating point is a point not only considering the efficiency of the engine but also considering both the efficiency of the engine and the generator. That is, the power control method according to an embodiment further includes an ultracapacitor to perform thermostat control to reduce sudden power change of the battery and to reduce battery usage.

The operation of the engine and the generator is indicated by S _{e / g} . When S _{e / g} is 1, the engine and the generator are operated. When S _{e / g} is 0, the engine and the generator are stopped. At this time, the power distribution of the three energy sources, that is, the engine and the generator, the battery, and the ultracapacitor are represented by Equation 1 below.

As described above, the required power of the ultracapacitor is the required power of the engine and the generator, minus the required power of the battery. In Equation 1, LPF is a low pass filter function. That is, in the step S150 of distributing the required power, the high frequency region of the required power of the battery is to be accommodated by the ultra wave capacitor, and the low frequency region is to be accommodated by the battery. This ensures that the power required by the battery does not change quickly.

Compensation power, which is the power that the battery compensates for the ultracapacitor, is determined by the difference between the current state of charge and the target state of charge of the ultracapacitor. That is, in the calculating of the compensation power (S140), the compensation power is calculated using a compensation power constant, a difference between the current and target charging states of the ultracapacitor, and a compensation coefficient for an accelerator pedal change.

That is, P _{ucap . The SOC} is the compensation power that the battery compensates with the ultracapacitor according to the speed of the vehicle and the rate of change of the accelerator _pedal.It is the difference between the current state of charge (SOC _ucap ) and the target state of charge (SOC _{ucap . Tar} ) of the _{ultracapacitor} and the rate of change of the accelerator pedal. Therefore, it is calculated as in Equation 2 below.

P _{ucap . comp} is the compensating power constant. Again, k _{ucap . The SOC} represents the difference between the current state of charge of the _{ultracapacitor} (SOC _ucap ) and the target state of charge (SOC _{ucap . Tar} ), which is a term for controlling the state of charge of the ultracapacitor according to the speed of the vehicle.

The power control method according to an embodiment of the present disclosure further includes changing a target state of charge of the ultracapacitor according to the speed of the vehicle. 1 shows the target state of charge (SOC _{ucap . Tar} ) of an ultracapacitor as a function of the speed of the vehicle.

If the speed of the vehicle is high, it is more likely to decelerate than the rate of acceleration of the vehicle. Therefore, it is necessary to lower the state of charge of the ultracapacitor to receive a large amount of regenerative braking energy during regenerative braking. On the contrary, if the vehicle is low speed, the vehicle is likely to accelerate, so the charging state of the ultra capacitor should be increased so that the electric power required for acceleration is output from the ultra capacitor. To achieve this, SOC _{ucap . Increase the tar} to keep the ultracapacitors in a high state of charge, or SOC _{ucap .} Lower the _tar to keep the ultracapacitor low charge.

In addition, k _APS is a compensation factor for acceleration pedal changes, which reduces the power the battery compensates for when the driver presses the pedal to accelerate the vehicle, allowing the ultracapacitor to output a greater amount of electrical power.

The operation of the engine according to the state of charge of the battery is shown in FIG. 2. SOC _bat in FIG _{. upper} is the _upper limit of battery charge, SOC _{bat . lower} is the allowable lower limit of the state of charge of the battery, and t _s is the sampling time to indicate the previous state.

In the series hybrid vehicle according to the embodiment of the present invention, the control unit operates the engine 1 and the generator 2 based on the state of charge of the battery 4, and calculates the required power. Here, the control unit is based on the required power, the first compensation power for the state of charge of the battery 4, and the second compensation power for the state of charge of the ultracapacitor 5, the engine 1 and the generator 2 It is characterized by calculating the required power.

Referring to FIG. 10, as a power control method of a series hybrid vehicle according to another embodiment, a series hybrid including an engine 1, a generator 2, a battery 4, and an ultracapacitor 5 as an energy source is provided. It relates to a power control method of a vehicle. According to another exemplary embodiment, a power control method includes determining whether to operate an engine and a generator based on a state of charge of the battery (S210), required power, first compensation power for a state of charge of the battery, Calculating a required power of the engine and the generator based on a second compensation power for the state of charge of the ultracapacitor (S22), and calculating a third compensation power that the battery compensates with the ultracapacitor ( S40 and distributing the necessary power based on whether the engine and the generator are in operation (S50).

The power control method according to another embodiment is a power follower control strategy. Unlike the thermostat control strategy, the electric power output from the engine and the generator is changed according to the state of charge of the battery rather than a constant value. . Accordingly, the battery usage is reduced more than in one embodiment, and since the operation of the engine and the generator is determined in consideration of the input / output power of the battery as well as the battery charging state, the operating range of the battery charging state is also reduced. Longer battery life than control method.

The calculating of the required power of the engine and the generator (S220) may include calculating the first required power by adding the required power, the first compensation power, and the second compensation power, and excessive charging of the battery. And comparing a range for preventing a discharge with the first required power, and calculating a second required power based on a result of comparing the operation of the engine and the generator and the comparing process. . In addition, calculating the required power of the engine and the generator (S220), the process of continuously calculating the average value of the second required power for one cycle, and after the passage of one cycle, the average value of the second required power and Calculating a difference between the required power of a previous cycle, comparing the difference between the required power and a predetermined reference power, and changing the second required power according to a comparison result to determine the required power of the engine and the generator. It is configured to include.

That is, the power control method according to another embodiment reduces the fast operating point change of the engine and the generator using an ultracapacitor, and removes the high frequency region of the power required for the battery. Another embodiment distributes power to each energy source through a total of three steps.

In the first step, the power requirements of the engine and generator are determined first. In general, the power follower control strategy calculates the required power of the primary engine and generator using only the electric power required by the drive motor according to the required torque of the driver and the state compensation power for the battery state of charge. However, in the power control method according to another embodiment, the charge compensation power for the ultra-capacitor charge state is also calculated to calculate the required power of the engine and the generator. The equation for this is shown in Equation 3 below.

Where P _{ucap . The SOC} is a first compensation power compensated by the engine and the generator by the ultra capacitor, and may be calculated in the same manner as the calculation of the compensation power in one embodiment. In addition, P _bat.SOC is the second compensation power that the engine and generator compensate with the battery. The second compensation power is also obtained by multiplying the compensation value (k _{bat . SOC} ) for the difference between the current state of charge and the target state of charge of the battery by the charge power constant (P _{bat .. comp} ) of the battery.

Referring to FIG. 3, in the second step, after calculating primary power requirements of the engine and the generator as described above, the engine on / off operation is determined using the first power demand. The calculated power requirements of the engine and generator are P _{min .} , Which is a fuel efficient section in the Optimal Operating Line (OOL) _{. OOL} and P _{max .} Limited to between _OOLs .

According to another exemplary embodiment, the power control method determines the operation of the engine and the generator using not only the state of charge of the battery but also the first required power P _{e / g1} of the engine and the generator. Where P _{eng . off} is the charge limiting power constant of the battery, which is used as a condition to prevent the battery from being charged with excessive power. P _{max .} By using _OOL , the battery is used as a condition to prevent excessive discharge.

Finally, in the third stage, the required power of the engine and the generator is finally modified to prevent the operating points of the engine and the generator from changing rapidly. At this stage, there are two variables that can be used to modify the power requirements of the engine and generator.

One is the holding time (T _a) if it is determined that the required power of the engine and the generator, kept for a certain period of time the requested power. The other is the required power change limiting power P _delta to change the required power of the engine and the generator when the required power changed when the required power of the engine and the generator is changed is greater than the required power change limiting power.

That is, the holding time (T _a) of the engine and the generator required power is maintained but, during this time P _{e / g2} average value (P _{e / g2. Ave)} for is continuously calculated. The control unit corrects the required power P _{e / g} of the engine and the generator when the holding time passes. The control unit is a mean value of P _{e /} P _{e g2 / g2.} Compare _ave with the required power of the previous engine and generator (P _{e / g} (tT _a )). The control unit then sets the power requirements of the engine and generator to P _{e / g2} when the difference between the two required powers is greater than the required power change limiting power P _{delta .} Changing to _ave and below the required power change limit power maintains the previous engine and generator power requirements.

Where T _a is a function of the absolute value of k _{bat .. SOC} and is determined as shown in FIG. 4. If the value of | k _{bat .. SOC} | is large, T _a is made small. If this value is small, T _a is made large. k _{bat . A} large absolute value of the _SOC means that the current state of charge of the battery is far from the target state of charge of the battery. Therefore, T _a is reduced in order to quickly compensate battery compensation power with engine and generator power. When T _a decreases, the required power of the engine and generator changes rapidly, and conversely, increases T _a to slow the change of operating points of the engine and generator.

If the _delta P is near to the optimum operating point (OOP) of P _{e / g2} The engine and the generator as a function of P _{e / g2,} the larger this value, and the optimum operating point is far smaller this value. This is to change the required power of the engine and the generator even when the engine and the generator is operated near the optimum operating point, and the small change does not change the required power of the engine and the generator, and when it is far from the optimum operating point. That is, by doing so, the required power of the engine and the generator plays a role to operate a lot near the optimum operating point. The content thereof is as shown in FIG. 5. In consideration of the above contents, power can be finally distributed to all energy sources as shown in Equation 5 below.

The third compensation power that the battery compensates with the ultra capacitor is determined according to a difference between a current charge state and a target charge state of the ultra capacitor, as in the exemplary embodiment. That is, the calculating of the third compensation power (S240) may include calculating the third compensation power by using a compensation power constant, a difference between current and target charging states of the ultracapacitor, and a compensation coefficient for an accelerator pedal change. do.

In another embodiment, the control unit calculates the output power that the battery 4 and the ultracapacitor 5 should output according to the required power of the engine 1 and the generator 2, and outputs the output power. Is distributed to the required power of the battery 4 and the ultracapacitor 5, and then the required power 2 of the engine 1 and the generator is calculated to distribute the required power.

Referring to FIG. 11, a power control method of a series hybrid vehicle according to another embodiment is a power control method of a series hybrid vehicle that supplies necessary power by providing an engine, a generator, a battery, and an ultracapacitor as energy sources. . According to another embodiment of the present invention, a power control method includes calculating an output power to be output by the battery and the ultracapacitor according to the required power of the engine and the generator (S310), and using the output power as the required power of the battery. And distributing the required power of the ultracapacitor (S320), calculating the required power of the engine and the generator (S330), and using the calculated power requirements of the engine and the generator to divide the required power into each energy. Dispensing to a circle (S340) is configured.

The power control method according to another embodiment relates to an Equivalent Consumption Minimization Strategy (ECMS) control strategy for distributing the power of each energy source to minimize the fuel consumption in generating the electrical power required for the drive motor. The battery 4 and the ultracapacitor 5 can generate electric energy without fuel consumption. However, since the battery 4 and the ultracapacitor 5 recharge as much as the electric power consumed for managing the state of charge, the battery 4 and the ultra capacitor 5 need to be charged using an engine and a generator.

In other words, generating electric energy using a battery and an ultracapacitor does not directly consume fuel, but it can be represented as an equivalent fuel consumption because fuel and fuel must be consumed later by an engine and a generator. The power control method according to another embodiment distributes power to each energy source so as to minimize the fuel energy directly consumed by the engine and the generator and the equivalent fuel energy generated by using the battery and the ultra capacitor.

The power control method according to another embodiment performs optimization in real time in two steps.

In the first stage, power is distributed between two energy storage devices (battery and ultra capacitor) according to the power requirements of the engine and generator. In the step of distributing the output power (S320), the output is distributed in consideration of the difference between the previous required power of the battery and the current required power of the battery. In addition, the step of distributing the output power (S320), in consideration of the difference between the current state of charge and the target state of charge of the ultracapacitor.

In other words, before optimally distributing the required power of the three energy sources, the output power to be output from the energy storage device is first calculated according to the required power of the engine and generator, and accordingly, the required power of the battery and the ultracapacitor is optimized. To distribute.

In this step, the purpose is to distribute the required power according to the characteristics of the battery and the ultracapacitor, so calculate the output power that should be output from the energy storage device according to the required power of the engine and generator and distribute it optimally to the battery and the ultracapacitor. do.

The instantaneous cost function for this is represented by Equation 6 below, and when the optimization is performed, the power of the battery and the ultracapacitor according to the required power of the engine and the generator is determined.

The problem of minimizing the above cost function must satisfy the following constraint (Equation 7).

The power required to output the required power in each energy storage device is as shown in FIG. Referring to FIG. 6, output power of a battery and an ultra capacitor may be distributed as shown in Equation 8 below.

In Equation 8, P _{bat . in} and P _{ucap . in} is the electrical power that must be actually output from each energy storage device in order to supply P _bat and _Pucap , the required power of the battery and ultracapacitor, to the system voltage bus.

η _{dc . con} is the efficiency of the DC-DC converter and the current i _bat flowing in the battery and the ultracapacitor And i _ucap Can be obtained through the following equations.

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If so,

if, If so,

Since the power control method according to another embodiment solves the optimization problem every moment, it is difficult to use modeling considering the dynamic characteristics of the battery and the ultracapacitor.

Therefore, the power control method according to another embodiment further considers the term for the absolute value of the difference between the power demand of the previous battery and the power demand of the current battery in order to take into account such dynamic characteristics. This term serves to show the LPF effect in power distribution between two energy storage devices.

In Equation 6, α serves as a time constant in LPF. In other words, the larger α, the greater the LPF effect in power distribution between the battery and the ultracapacitor.

Further, to control S _ucap therefore the state of charge of the ultracapacitor in the speed of the vehicle Introduce. It is defined as shown in FIG. 7 as a function of k _{ucap .. SOC} representing the difference between the current state of charge and the target state of _charge of the _{ultracapacitor} . This is giving a weight to the electrical power output from the ultra-capacitor, or charge, depending on k _{ucap .. SOC} serves to make the ultracapacitor follow the target state of charge.

As such, when the power distribution of the two energy storage devices according to the change in the required power of the engine and the generator is finished, the optimal power distribution is performed in consideration of the required power of the engine and the generator in the second step. In this case, the optimization problem is calculated by calculating the equivalent fuel energy according to the fuel energy consumed by the engine and the generator and the electric power consumed by the energy storage device.

In the distributing the required power (S340), the fuel consumption of the engine and the generator and the equivalent fuel energy according to the power consumption of the battery and the ultracapacitor are distributed. In addition, in the step (S340) of distributing the required power, while the state of charge of the battery to operate within a predetermined range to distribute. In addition, in the step (S340) of distributing the required power, distribution is performed in consideration of changes in operating points of the engine and the generator.

In the second step, since the optimum battery and ultracapacitor powers are calculated according to the power requirements of the engine and generator in the first step, the instantaneous cost function as shown in Equation 12 for the engine and generator power requirements You can optimize

The problem of minimizing the above cost function must satisfy the following constraint.

Here, S _bat weights the electrical power of the battery according to the state of charge of the battery so that the state of charge of the battery operates within a predetermined range when distributing required power to each energy source through a power control method according to another embodiment. It is as shown in FIG. In addition, the power control method considers the weight by S _bat in addition to the weight by the ultracapacitor S _ucap .

Electrical power discharged or charged from batteries and ultracapacitors can be converted into equivalent fuel energy using the average efficiency of the engine and generator (η _{e / g..ave} ). The average efficiency of the engine and the generator can be expressed by Equation 14 below as an average value of the efficiency at the point where the engine and the generator are operated while the vehicle is running.

In addition, P _{e / g .. change} in Equation 12 is a variable for considering the change of the operating point of the engine and the generator. When the operating points of the engine and the generator change, so that the angular velocity of the engine and the generator changes, the rotational inertia energy changes. As a result, penalties were applied according to changes in operating points of engines and generators. This is a term for expressing additional fuel energy consumed by the change of the operating point of the engine and the generator in the actual vehicle. Assuming that the generator changes the inertial energy of the engine and the generator, the equivalent fuel energy can be calculated as in Equation 15 below.

Η _{gen .. change} in Equation 15 Is the efficiency of the generator.

In the above another embodiment, parts not mentioned are replaced with those mentioned in one embodiment or another embodiment, and are omitted.

As described above, the series hybrid vehicle and its power control method according to the embodiments of the present invention relate to an upper control algorithm of the series hybrid vehicle, and include a thermostat control strategy, a power follower control strategy, and an ECMS control strategy. to provide. Embodiments of the present invention have an ultracapacitor to reduce the utilization of the battery, the ultracapacitor to cover the high frequency region of the power required, and improve the efficiency of using the ultracapacitor in consideration of the state of charge of the ultracapacitor. Accordingly, embodiments of the present invention reduce the battery usage rate, efficiently distribute power, and increase fuel economy.

1: engine 2: generator
3: converter 4: battery
5: Ultra Capacitor 6: DC-DC Converter
7: smooth part 8: inverter
9: motor

Claims (24)

delete delete delete delete delete delete delete In the power control method of a series hybrid vehicle having an engine, a generator, a battery and an ultracapacitor as an energy source,
Determining whether to operate the engine and the generator based on a state of charge of the battery;
Calculating the required power of the engine and the generator based on power required for driving the motor, first compensation power for the state of charge of the battery, and second compensation power for the state of charge of the ultracapacitor;
Calculating a third compensation power that the battery compensates with the ultra capacitor; And
And distributing the required power based on whether the engine and the generator are operated.
Calculating the required power of the engine and generator,
Calculating a first required power by adding the required power, the first compensation power, and the second compensation power;
Comparing a range for preventing excessive charging and discharging of the battery with the first required power; And
And calculating a second required power based on a comparison between the operation of the engine and the generator and a comparison result of the comparing process. The method of claim 8, wherein the calculating of the required power of the engine and the generator comprises:
Continuously calculating an average value of the second required power for one period;
Calculating a difference between the average value of the second required power and the required power of a previous period after one cycle has elapsed; And
Comparing the difference between the required power and a predetermined reference power, and determining the required power of the engine and the generator by changing the second required power according to the comparison result. Control method. 10. The method of claim 9,
And the third compensation power is determined according to a difference between a current state of charge and a target state of charge of the ultracapacitor. The method of claim 10, wherein calculating the third compensation power comprises:
And calculating the third compensation power using a compensation power constant, a difference between current and target charging states of the ultracapacitor, and a compensation coefficient for an accelerator pedal change. 12. The method of any of claims 8 to 11, wherein distributing the required power comprises:
And a high frequency region of the required power of the battery to cover the ultra high frequency capacitor, and a low frequency region to cover the battery. delete delete delete delete delete delete An engine and a generator driven by the engine;
A converter for converting the required power of the generator into a first direct current power;
A battery for supplying a second DC power source;
A DC-DC converter converting an ultra capacitor and an output power of the ultra capacitor into a third DC power;
A smoothing unit connected in parallel to the converter and the direct-current converter;
An inverter connected to the smoothing unit and supplying power required for driving the motor; And
And a control unit for distributing the required power to the engine and generator, a battery, and an ultra capacitor.
Wherein the control unit comprises:
The high frequency region of the portion excluding the required power of the engine and the generator of the required power so that the Ulpa capacitor can afford, the low frequency region to cover the battery,
The first required power is calculated by summing the required power, the first compensation power, and the second compensation power, and a range for preventing excessive charge / discharge of the battery is compared with the first demand power, and the engine And calculating a required power of the engine and the generator by calculating a second required power based on whether the generator is operated and a comparison result of the comparing process. The method of claim 19,
A first sensor detecting a charging state of the battery; And
And a second sensor for sensing a state of charge of the ultra capacitor. The method of claim 20, wherein the control unit,
And operating the engine and the generator based on the state of charge of the battery, and calculating the required power. The method of claim 21,
When the engine and the generator are in operation, the required power of the engine and the generator is a series hybrid vehicle, characterized in that the power at the optimum operating point with the best efficiency of the engine and the generator. The method according to any one of claims 19 to 22, wherein the control unit,
Continuously calculating an average value of the second required power for one period, and after a period of elapses, calculates a difference between the average value of the second required power and the required power of a previous period, the difference between the required power, and a predetermined reference power And comparing the second power requirements and determining the power demands of the engine and the generator according to the comparison result. The method of claim 23, wherein the control unit,
And calculating the third compensation power using a compensation power constant, a difference between current and target charging states of the ultracapacitor, and a compensation coefficient for an accelerator pedal change.

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