KR100569016B1 - Voltage balance control device of energy storage system for hybrid type - Google Patents

Abstract

In a hybrid type energy storage device in which a common battery and a supercap are connected in parallel to a 42V hybrid electric vehicle to which an integrated starter generator (ISG) is applied, the voltage balance between two energy storage devices can be controlled by a simple system structure. The voltage balancer of the hybrid energy storage device,

ISG, an integrated starter and generator, and an MCU that controls engine voltage by controlling each phase voltage when the ISG operates as a motor, and a MCU that processes the generated voltage as a constant voltage when operating as a generator according to the braking control. Connect the normal battery and the supercap in parallel with the energy storage characteristics, connect the MCU and the supercap, all the electrical load is connected to operate the voltage of the normal battery, and is connected between the normal battery and the supercap A diode which maintains a voltage balance and is connected in parallel with the diode, and when the voltage balance by the turn-on of the diode is maintained is switched on by the control of the controller to maintain the equalization balance between the supercap and the general battery. It characterized in that it comprises a switch.

Supercap, Hybrid Energy Storage, General Battery, ISG

Description

VOLTAGE BALANCE CONTROL DEVICE OF ENERGY STORAGE SYSTEM FOR HYBRID TYPE}

1 is a block diagram of a voltage balance control device of a hybrid energy storage device according to the present invention.

Figure 2 is a block diagram of a voltage balance control device of a conventional hybrid energy storage device.

The present invention relates to a hybrid energy storage device, and more particularly, a lead-acid battery (hereinafter referred to as a "general battery") and a supercap are parallel to a hybrid electric vehicle for a 42V system to which an integrated starter generator (ISG) is applied. The present invention relates to a voltage balancer of a hybrid energy storage device for controlling the structure of a simple system of voltage balance between two energy storage devices.

In general, in developing a hybrid electric vehicle, a function of converting mechanical energy into electrical energy during regenerative braking to instantly charge a large amount of energy in an energy storage device and discharge a large amount of energy from an energy storage device in an instant when it is accelerated. Energy storage devices are being studied.

In this case, energy and power can be considered as two factors to consider in the characteristics of the storage device, and how much energy can be stored according to the unique characteristics of the energy storage device and how quickly and effectively the stored energy can be used. It is an argument.

Generally, a general battery used in a general vehicle is a storage device that involves a chemical reaction during an energy input / output process, but may store a relatively large amount of energy, but has a disadvantage in that a large amount of energy is charged or discharged in a short time.

In addition, it has a relatively low energy density and can store a lot of energy, but the output density is low, there is a disadvantage that can not guarantee the life of the battery under operating conditions that require frequent charging and discharging and large current input and output.

There is a limitation in applying a general battery having such characteristics as an energy storage device of an electric vehicle or a hybrid vehicle. Currently, a NiMH battery is applied as an energy storage device of an electric vehicle or a hybrid vehicle. It is acting as a factor in raising prices.

In particular, in order to realize fuel efficiency improvement through recovery of the regenerative braking energy and the idle stop & start function, which is being implemented in a hybrid electric vehicle for 42V system, which has recently been attracting attention, the application of general batteries is required. It is raised that there is a limit.

As one of the measures to compensate for the shortcomings of the conventional battery, the output density is about 10 times or more than that of the general battery, and the energy storage capacity is limited because the energy density is low, but it does not involve chemical reaction during the energy charging and discharging process. In addition, a method of applying a super cap (Super-Capacitor) having the advantage of being able to charge and discharge a large current has been proposed.

However, when the supercap is applied as an energy storage device, it is able to handle the instantaneous energy flow and improve the fuel efficiency and acceleration performance of the vehicle. However, the energy density is relatively low compared to the general battery as the energy storage device alone. It can not be used as a disadvantage.

To this end, a hybrid energy storage device suitable for large current operation is being researched by combining a 36V general battery having a large energy storage capacity and a supercap having a high instantaneous output in parallel.

When the supercap is applied as an energy storage device, the energy stored in the supercap during the momentary acceleration of the vehicle is supplied to the motor-driven ISG to assist the engine power, thereby improving the acceleration performance, and the current engine torque is new to the ISG torque. Since the developed engine sizing is combined, the engine can be used in the same way as the current vehicle using less torque, and the regenerative braking area can be expanded due to the high-efficiency charging / discharging characteristics of the supercap. Can improve fuel economy.

In addition, since the internal resistance of the supercap is less changeable with temperature, it is possible to supply constant power even at low temperatures, thereby improving low temperature starting characteristics.

Comparing the main characteristics of the normal battery and the super cap is shown in Table 1 below.

Main performance Normal battery (36V) Super Cap (2.7V / Cell) Principle of reaction  Chemical Reaction Between Electrode Active Material and Electrolyte  Adsorption-desorption reaction of ions in electrolyte Voltage and temperature range 43.2 ~ 32.5V -10 ~ + 60 ℃ 48.6 ~ 24.3V -40 ~ + 75 ℃ Charging time 1 to 5 [hr] 0.3 to 30 [sec] Discharge time 0.3 to 3 [hr] 0.3 to 3 [sec] Energy density [Wh / kg] 10 to 100 1 to 10 Number of charge / discharge cycles 100,000 More than 500,000 Filling density [W / kg] 1,000 or less Less than 10,000 Charge and discharge efficiency [%] 0.7 to 0.85 0.85-0.98

When the supercap having the above characteristics and a normal battery are connected in parallel and used as an energy storage device, a voltage difference occurs between the two energy storage devices, and thus means for maintaining a voltage balance is further included. .

As shown in FIG. 2, the EMS is installed between the supercap 4 and the general battery 5 and maintains a voltage balance against voltage difference generated between both energy storage devices through power conversion. (Energy Management System; 3) is provided.

The EMS (3) detects the current, voltage, and temperature of the super cap (4) and the general battery (5) to monitor the state of the super cap (4) and the general battery (5) and then the super cap (4) and EMS function unit 3a for controlling overall operation for maintaining the voltage balance between the normal battery 5, maintaining a state of charge (SOC) and maintaining a state of health (SOH), and control of the EMS function unit (3a) According to the DC / DC converter (3b) to maintain the voltage conversion between the supercap (4) and the normal battery (5) and voltage supply and braking for power assistance to the ISG (1) in the state of momentary acceleration When the regenerative energy recovery and the ISG (1) operates in the mode of the generator is configured to include a switch (SW1, SW2) for selecting and determining the path for recovering the generated energy.

In the conventional hybrid energy storage device having the above-described configuration, an expensive DC / DC converter and a control means for controlling the same must be applied to maintain the voltage balance between the supercap and the general battery having different characteristics, so that the vehicle additional This will act as a factor of cost increase, and many problems that require space should be secured.

The present invention has been invented to solve the above problems, the object of the two energy in the hybrid type energy storage device that is applied to connect the common battery and the supercap in parallel to the hybrid electric vehicle for 42V system to which ISG is applied By controlling the voltage balance between the storage devices by applying a simple system structure, it is possible to provide efficiency in reducing the cost of the vehicle and utilizing the limited space.

According to an aspect of the present invention, there is provided a hybrid electric vehicle for a 42V system to which a hybrid type energy storage device is applied, the integrated starter and generator being an ISG; When the ISG is operated as a motor, it supports an engine torque by controlling each phase voltage, and when operating as a generator under braking control, the MCU includes a MCU that processes the generated voltage as a constant voltage, and has a general battery having different energy storage characteristics. And a supercap connected in parallel, the MCU and the supercap, and all the electrical load is connected to operate the voltage of the normal battery, and the diode connected between the normal battery and the supercap to maintain the voltage balance and ; It is connected in parallel with the diode, if the voltage balance is maintained by the turn on of the diode is switched on by the control of the controller, characterized in that it comprises a switch for continuously maintaining the equalization balance between the supercap and the general battery Provided is a voltage balance control device for a hybrid energy storage device.

The diode is turned on when the cathode terminal is connected to the + terminal of the general battery, the anode terminal is connected to the + terminal of the supercap, and the voltage of the supercap is lower than that of the general battery as the ISG operates as a motor. Main battery voltage is additionally supplied to ISG and supercap to maintain voltage balance between supercap and normal battery, and when regenerative energy is stored in supercap by brake driving, voltage balance between supercap and normal battery is destroyed. Breaking down at the time point is operated in the reverse direction, characterized in that to supply the charging voltage to the normal battery.

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

As can be seen in Figure 1 the voltage balance control device of the hybrid energy storage device according to the present invention is ISG 10 and MCU 20, the load 30, the general battery 40, the supercap 50, It is comprised including the diode D and the switch SW11.

In the above, the ISG 10 is an integrated starter and a generator. When the assistance of the power is required, the ISG 10 is driven by a motor to assist the engine power by driving the voltage supplied from the energy storage device to provide the acceleration performance of the vehicle, and regenerate the vehicle. When braking, it operates as a generator to recover mechanical energy as electrical energy.

When the ISG 10 is operated as a motor, the MCU 20 supplies the voltage supplied from the shooter cap 50 to each phase voltage so that the ISG 10 assists the engine power, and the ISG 10 When operated as a generator, it generates a constant voltage of approximately 42V from a three-phase power source generated from the ISG 10.

The load 30 refers to all electric loads provided in the hybrid electric vehicle, and is connected to the general battery 40 charging a voltage of approximately 36V to be operated by voltage.

The supercap 50 is connected in parallel with the general battery 40, is connected to the MCU 20, and stores the constant voltage generated and applied by the MCU 20, the ISG 10 is operated by a motor to power If assistance is required, the engine power is assisted through the output of the stored voltage.

The diode D has a cathode terminal connected to the + terminal of the normal battery 40 and an anode terminal connected to the + terminal of the supercap 50, so that the ISG 10 serves as a motor to perform a power assist function. In operation, when the voltage of the supercap 50 becomes lower than the voltage of the general battery 40 according to the discharge of the voltage, the battery is turned on, and the voltage of the general battery 40 is additionally supplied. This maintains the voltage balance.

The switch SW11 is connected in parallel with the diode D, and when the voltage balance is maintained by the turn-on of the diode D, the switch SW11 is switched on under the control of the controller (not shown), so that the supercap 50 And the equalization balance between the normal battery 40 and continuously.

Operation of maintaining the voltage balance between the two energy storage devices in the present invention having a configuration including the function as described above is as follows.

In the hybrid electric vehicle for 42V system to which the ISG 10 is applied and the supercap 50 and the general battery 40 charging the voltage of approximately 36V are connected in parallel, the ISG 10 is driven by the rapid acceleration. When the supercap 50 acts as a motor to assist the engine torque, the supercap 50 supplies the stored voltage to the ISG 10 by supplying the MCU 20 to the instantaneous acceleration performance.

Therefore, the voltage level becomes lower than the voltage of the normal battery 40 according to the discharge of the voltage charged in the supercap 50. Accordingly, since the diode D is turned on, the voltage charged in the general battery 40. Also discharged and supplied to the voltage required for the start of the ISG (10) and at the same time is supplied to the supercap 50 as a charging voltage.

When the voltage level of the general battery 40 is balanced by the voltage level of the supercap 50 by the flow of the above voltage, the upper controller, which is not shown, monitoring the switch is connected in parallel to the diode D. The SW11 is turned on to form a current loop between the general battery 40 and the super cap 50.

As such, as the supercap 50 and the general battery 40 are connected in parallel, the voltage balance is kept stable.

In addition, when the ISG 10 is operated as a generator to recover mechanical energy as electrical energy according to the driving of the brake while driving, the upper controller (not shown) turns off the switch SW11 connected to the diode D to turn off the ISG 10. Regenerated energy generated by the constant voltage by the MCU 20 is stored in the supercap 50, the diode (D) when the voltage stored in the supercap 50 is higher than the voltage of the general battery 40 Is operated in the reverse direction by the breakdown, so that the regenerative energy is supplied to the general battery 40, whereby it is charged to a voltage maintained in balance with the supercap 50.

As described above, the present invention applies a simple structure to maintain a stable voltage balance between hybrid energy storage devices, thereby providing cost savings and providing efficient use of limited space.

Claims (4)

In a hybrid electric vehicle for a 42V system to which a hybrid energy storage device is applied, An ISG which is an integrated starter and generator; When the ISG operates as a motor, it controls the phase voltage to assist engine torque, and when operated as a generator according to the braking control, the MCU is provided to process the generated voltage as a constant voltage. Connect the normal battery and supercap in parallel with different energy storage characteristics, connect the MCU and the supercap, and connect all the electric loads to the voltage of the normal battery, A diode connected between the normal battery and the supercap to maintain a voltage balance; It is connected in parallel with the diode, if the voltage balance is maintained by the turn on of the diode is switched on by the control of the controller, characterized in that it comprises a switch for continuously maintaining the equalization balance between the supercap and the general battery Voltage balance control of hybrid energy storage device. The method of claim 1, The diode is turned on when the cathode terminal is connected to the + terminal of the general battery, the anode terminal is connected to the + terminal of the supercap, and the voltage of the supercap is lower than that of the general battery as the ISG operates as a motor. The voltage balance control device of the hybrid energy storage device, characterized in that the voltage of the normal battery is additionally supplied to the ISG and the super cap to maintain the voltage balance between the super cap and the normal battery. The method of claim 1, When the regenerative energy is stored in the supercap according to the brake driving, the diode is braked down at the time point when the voltage balance between the supercap and the normal battery is destroyed, and is operated in the reverse direction. Voltage balance control of mold energy storage. The method of claim 1, The switch is controlled by the host controller, the voltage balance control device of the hybrid type energy storage device, characterized in that the switching off when driving the brake.

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