KR100484893B1 - Method of automotive battery charging - Google Patents

Abstract

The present invention relates to a neutral point of a three-phase alternating current winding of an integrated starter and generator (ISG) of a 42V power supply system vehicle; Charging the 42V battery or the 14V battery by connecting a 14V battery of a 14V power supply system car between the ISG and the DC link of the inverter connecting the 42V battery of the vehicle, for example, the positive terminal or the negative terminal of the inverter. It is about how to.

According to the method according to the present invention, by using the power supply of the existing 14V power supply system car without a separate device, it is possible to start the car of the 42V power supply system that the battery is completely discharged and impossible to start, and conversely, the 42V power supply The power supply of the supply system car can be used to start the 14V power supply system car.

Description

How to charge a car battery {Method of automotive battery charging}

The present invention relates to a neutral point of a three-phase AC winding of an integrated starter and generator (ISG) of a 42V power supply system vehicle; Charging the 42V battery or the 14V battery by connecting a 14V battery of a 14V power supply system car between the ISG and the DC link of the inverter connecting the 42V battery of the vehicle, for example, the positive terminal or the negative terminal of the inverter. How to It is about.

In today's cars, 14V batteries are used as the main power source. However, next-generation automobiles, which are fuel efficient, stable, and convenient, require a more efficient power supply system. That is, because more load devices are mounted than before, more power must be supplied. For example, an active suspension system is necessary for safety or driver's convenience, but due to the high power consumption, it is difficult to provide a vehicle with an existing 14V power supply system.

The 42V power supply system is expected to meet these needs. Since it can smoothly supply power to devices with high power consumption, it is likely to be used as a power supply system for next-generation automobiles.

However, not all vehicle load devices are designed for 42V. For example, if a car's lamp is to be used for a 42V supply, the filament must be thinner to produce the same light as a 14V supply. However, if the lamp is manufactured in this way, there is a problem that the filament can be easily broken by the vibration of the automobile. Therefore, a unidirectional DC / DC converter that converts 42V to 14V should be used to supply voltage to existing 14V automotive parts. 1 is a 42V using a one-way DC / DC converter as described above A power supply system is shown.

On the other hand, when using a one-way DC / DC converter as described above, the charging of the battery is a problem. In the situation where most cars adopt the 14V power supply system as of today, even if the battery is completely discharged and the car does not start, it is possible to start and charge the battery using another car's 14V battery (jump starting). starting)).

However, converting a 14-V power supply system to a 42-V power supply system will take a considerable amount of time, for example, several years, so if the 42V battery is discharged, the 42V battery should be replaced if the other car is a 14V battery instead of a 42V battery. Can't charge

To solve this problem, a method of using a bidirectional DC / DC converter capable of converting 42V and 14V voltages to each other has been proposed. Figure 2 shows a 42V power supply system using a bidirectional DC / DC converter as described above. In this case, connect the 14V battery of another car to the 14V battery of the 42V power supply system car, start by charging the 42V battery using the bidirectional DC / DC converter, and then recharge the 42V battery using the ISG. can do.

However, in the above method, since the bidirectional DC / DC converter is expensive, it is problematic in terms of cost.

In addition, the 14V power supply system can This is a problem if the car is a 42V power supply car rather than a 14V power supply car. In this case, a method of charging a 14V battery by receiving power from the 14V load side of FIG. 1 showing the 42V power supply system may be considered. However, the capacity of the 42V → 14V one-way DC / DC converter is very high for the 14V vehicle to be started. The problem is that it must be large.

In this regard, the present inventors have conducted intensive research to develop a vehicle battery charging method that can solve the above problems. As a result, the charging method according to the present invention can charge a 42V battery from a 14V battery, or vice versa, without using an expensive bidirectional DC / DC converter or a large capacity one-way DC / DC converter. It was confirmed that the present invention was completed.

It is therefore an object of the present invention to provide a novel method of charging a 42V battery or a 14V battery of an automobile.

It is also an object of the present invention to provide an automotive ISG which can easily perform the above charging method.

The present invention relates to a neutral point of a three-phase alternating current winding of an integrated starter and generator (ISG) of a 42V power supply system vehicle; By connecting a 14V battery of a 14V power supply system vehicle between the ISG and a DC link of an inverter connecting the 42V battery of the vehicle, the 42V battery or phase A method of charging a 14V battery.

Here, the DC link of the inverter collectively refers to the negative terminal or the positive terminal of the inverter.

In the present invention, when the 14V battery is connected between the neutral point of the three-phase AC winding of the ISG and the DC link of the inverter, that is, the negative terminal or the positive terminal of the inverter, when the switch of the inverter is properly opened and closed, the energy of the winding Can be moved to a 42V battery or a 14V battery.

Thus, with the 14V battery connected between the neutral point and the negative terminal of the inverter, switches located between the winding of each phase of the three-phase AC winding and the negative terminal or positive terminal of the inverter By opening and closing periodically, the 42V battery or the 14V battery can be charged.

As described above, in the case where the 14V battery is connected between the neutral point and the negative terminal of the inverter, when charging the 42V battery from the 14V battery, the winding of each phase of the three-phase AC winding and the positive terminal of the inverter In the open state, the switches located in between may be charged by periodically opening and closing the switches located between each phase winding of the three-phase AC winding and the negative terminal of the inverter.

Conversely, in the case of charging a 14V battery from a 42V battery, the switches positioned between the winding of each phase of the three-phase AC winding and the negative terminal of the inverter are turned off, so that each of the three-phase AC windings is turned off. Phase windings and the inverter The switches located between the positive terminals of the can be periodically opened and closed to charge.

Further, according to the present invention, with the 14V battery connected between the neutral point and the positive terminal of the inverter, between the winding of each phase of the three-phase AC winding and the negative terminal or positive terminal of the inverter By periodically opening and closing the switches located in the can be charged the 42V battery or the 14V battery.

As described above, in the case where the 14V battery is connected between the neutral point and the positive terminal of the inverter, in order to charge the 42V battery from the 14V battery, the winding of each phase of the three-phase AC winding and the cathode of the inverter The switches located between the terminals can be charged by periodically opening and closing the switches located between each phase winding of the three-phase AC winding and the positive terminal of the inverter in an open state.

On the contrary, in the case of charging a 14V battery from a 42V battery, the switches located between each phase winding of the three-phase AC winding and the positive terminal of the inverter are turned off, so that each of the three-phase AC windings is turned off. The switches located between the windings of the clothes and the negative terminal of the inverter may be periodically charged and opened.

When the switches are periodically opened and closed, they may be opened or closed at the same time, or may be opened or closed at regular intervals, preferably with a time difference of 1/3 of the switch opening / closing period.

In addition, the present invention is an automotive ISG, the neutral point of the three-phase AC winding of the ISG; A vehicle having a terminal connected to the neutral point outside of the ISG so that the battery can be easily connected between the DC link of the inverter connecting the ISG and the 42V battery of the vehicle, that is, the negative terminal or the positive terminal of the inverter. Provide an ISG for

Here, the battery connected between the neutral point and the DC link of the inverter will typically be a 14V battery of a 14V power supply system vehicle.

Hereinafter, with reference to the drawings will be described preferred embodiments of the present invention.

3 shows an engine-power system consisting of an ISG of a motor vehicle, an automotive battery, an inverter and an engine. In normal operation, the inverter drives the engine by applying an AC three-phase voltage of the required frequency and magnitude to the ISG by applying a pulse width modulation (PWM) to the vehicle battery voltage. On the contrary, when driving in the steady state, the ISG is driven by the engine, the driven ISG operates as a generator, and the generated power is charged to the battery by the inverter and supplied to the 42V load and the 14V load.

4 shows a circuit diagram of the engine-power system.

First, the neutral point of the three-phase AC winding of the automotive ISG; A method of charging a 42V battery from a 14V battery by connecting a 14V battery between the negative terminal of the inverter connecting the ISG and the 42V battery will be described.

The neutral point 1 of the three-phase AC winding of the ISG for automobiles; A 14V battery is connected between the negative terminal 2 of the inverter connecting the ISG and the 42V battery. At this time, the switches Q ₁ , Q ₃ and Q ₅ positioned between the winding of each phase of the three-phase AC winding and the positive terminal 3 of the inverter are left open and the three-phase AC winding By closing the switches Q ₂ , Q ₄ and Q ₆ located between the windings of each phase of the inverter and the negative terminal 2 of the inverter (on), the currents i _a , i _b and i _c of the three-phase AC windings of the ISG are closed. Increases.

After that, if the currents i _a , i _b and i _c are equal to or greater than a predetermined current value, the switches Q ₂ , Q ₄ and Q ₆ are turned off. At this time, the current flowing through the ISG winding passes through the diodes D ₁ , D _3, and D ₅ to charge the C _dc to charge the 42V battery.

With proper control of the voltage applied to C _dc , the magnitude of the current i _bat into the 42V battery can be properly controlled.

After that, when the currents i _a , i _b and i _c become smaller than a predetermined current value, the switches Q ₂ , Q ₄ and Q ₆ are closed again to increase the currents i _a , i _b and i _c , and again the switch Q _2. Repeat the process of opening, Q ₄ and Q ₆ .

As such, if the switching Q ₂ , Q _4, and Q ₆ are periodically repeated, the 42V battery may be charged to a desired voltage. This is the current flowing in the winding (inductor) of the ISG (the energy at this time Energy flows through the diode to the C _dc and 42V batteries.

When the 42V battery is charged by the minimum amount required to drive the engine using the ISG, the engine is driven by driving the ISG with an inverter, and when the engine is driven and the ISG operates as a normal generator, the applied 14V battery is recalled. The neutral point 1 of the three-phase AC winding of the ISG; It is separated from the negative terminal (2) of the inverter connecting the ISG and the vehicle battery. This allows the automotive 42V battery to be charged normally through the ISG and to power 42V and 14V loads.

An example of the currents i _a , i _b and i _c when the switches Q ₂ , Q ₄ and Q ₆ are simultaneously opened and closed at a predetermined period T is shown in FIG. 5.

However, when the switches Q ₂ , Q ₄ and Q ₆ are simultaneously opened and closed as described above, _a large pulsation current may occur in i _o or i _bat current which is the sum of the currents i _a , i _b and i _c . . These pulsating currents can adversely affect the lifetime of C _dc and the lifetime and charging efficiency of 42V or 14V batteries. In order to reduce the pulsating current, it is preferable that the switches Q ₂ , Q ₄ and Q ₆ are opened and closed at regular intervals, for example, with a time difference of about 1/3 cycles. Thus, FIG. 6 shows an example of the currents i _a , i _b , i _c and the sum of i _o currents when the switches Q ₂ , Q ₄ and Q ₆ are opened and closed with a time difference of 1/3 cycle.

If the flow rate D of the switch is exactly 2/3, the pulsating current of i _o disappears.

Here, the flow rate D is defined by the following equation.

In the above formula,

T is the switching cycle of the switch,

T _on is the time (T _on) of the state (on) with the switch closed.

In theory, if there is no loss of the circuit, the relationship between the flow rate D and the voltage is as follows:

Here, when a typical 14V power supply is connected to a 42V power supply, D will be around 2/3.

However, if the 42V battery is fully discharged, the flow rate D will be less than 2/3, in which case a slight pulsating current may appear at i _o .

Hereinafter, a method of charging the 14V battery from the 42V battery will be described.

Similar to charging a 42V battery from the 14V battery, the ISG for automobile The neutral point (1) of the three-phase AC winding of; A 14V battery is connected between the negative terminal 2 of the inverter connecting the ISG and the 42V battery.

This time, the switches Q ₂ , Q ₄ and Q ₆ positioned between the winding of each phase of the three-phase AC winding and the negative terminal 2 of the inverter are left off and the three-phase AC winding By closing the switches Q ₁ , Q ₃ and Q ₅ located between the windings of each phase of the inverter and the positive terminal 3 of the inverter (on), the currents i _a , i _b and i _c of the three-phase AC windings of the ISG are closed. Increases in the negative direction, ie the 14V battery is connected.

After that, if the currents i _a , i _b and i _c are equal to or greater than a predetermined current value in the negative direction, the switches Q ₁ , Q ₃ and Q ₅ are opened (off). At this time, when the switches Q ₁ , Q ₃ and Q ₅ are turned off, the currents i _a , i _b and i _c flow through the diodes D ₂ , D ₄ and D ₆ , respectively. After that, when the currents i _a , i _b and i _c become smaller than the predetermined current value in the negative direction, the switches Q ₁ , Q ₃ and Q ₅ are closed again to move the currents i _a , i _b and i _c in the negative direction. Increase, and repeat the process of opening switches Q ₁ , Q ₃ and Q ₅ again.

As such, if the switching Q ₁ , Q _3, and Q ₅ are periodically repeated, the energy of the 42V battery can be supplied to the 14V battery.

An example of the currents i _a , i _b and i _c when the switches Q ₁ , Q ₃ and Q ₅ are simultaneously opened and closed at a constant period T is shown in FIG. 7.

Similarly, the current i _a, i _b and i _c of the sum of i _o the switch so as to reduce the ripple current which can occur in the current Q _1, Q ₃ and Q ₅ the time difference from each other a predetermined interval, e.g., 1 / It is preferable to open and close each with a time difference of three cycles. Thus, FIG. 8 shows an example of the currents i _a , i _b , i _c and the sum of i _o currents when the switches Q ₂ , Q ₄ and Q ₆ are opened and closed with a time difference of 1/3 cycle.

If the flow rate D of the switch is exactly 1/3, the pulsating current of i _o disappears.

Here, the flow rate D is as defined above, and in theory, if there is no circuit loss, the relationship between the flow rate D and the voltage is as follows:

Here, when a typical 14V power supply is connected to a 42V power supply, D will be around 1/3.

As can be seen above, by changing the opening and closing of the switches Q ₁ to Q ₆ in the same power supply system, it is possible to charge the 42V battery from the 14V battery or the 14V battery from the 42V battery.

Hereinafter, as described above, the neutral point 1 of the three-phase AC winding of the automotive ISG; The neutral point (1) instead of connecting a 14V battery between the negative terminal (2) of the inverter connecting the ISG and the 42V battery; A method of charging the 42V battery or the 14V battery by connecting a 14V battery between the positive terminal 3 of the inverter will be described (not shown).

In this case, when charging a 42V battery from a 14V battery, the switches Q ₂ , Q ₄ and Q ₆ positioned between the winding of each phase of the three-phase AC winding and the negative terminal 2 of the inverter are open. At (off), the switches Q ₁ , Q ₃ and Q ₅ positioned between the winding of each phase of the three-phase AC winding and the positive terminal 3 of the inverter are periodically opened and closed to charge.

Conversely, in the case of charging a 14 V battery from a 42 V battery, the switches Q ₁ , Q ₃ and Q ₅ located between the winding of each phase of the three-phase AC winding and the positive terminal 3 of the inverter are open ( off), the switches Q ₂ , Q ₄ and Q ₆ located between the winding of each phase of the three-phase AC winding and the negative terminal 2 of the inverter are periodically opened and closed to charge.

Likewise, the switches to be opened and closed may be simultaneously opened and closed at a predetermined period T, but in order to reduce the pulsating current, the switches are preferably opened and closed at regular intervals.

As can be seen above, the present invention connects the negative terminal of the 14V battery of the 14V power supply system car to the negative terminal of the inverter connecting the combined start-generator of the vehicle 42V power supply system and the 42V battery of the car, Connect the positive terminal of the 14V battery to the neutral point of the three-phase alternating current winding of the composite start-up generator; The positive terminal of the 14V battery is connected to the positive terminal of the inverter, and the negative terminal of the 14V battery is connected to the neutral point of the three-phase AC winding, and then the opening and closing of the switches Q ₁ to Q ₆ are different from the 14V battery. The 42V battery may be charged or the 14V battery may be charged from the 42V battery.

According to the method according to the present invention, it is possible to charge a car 42V battery with a car 14V battery without a special device, or, on the contrary, to charge a 14V battery from a 42V battery, so that an expensive bidirectional DC / DC converter or a large one-way DC / There is no need to use a DC converter.

Therefore, it is possible to solve the problem that occurs when switching from a 14V power supply system to a 42V power supply system in an automobile.

1 shows a 42V power supply system using a one-way DC / DC converter,

2 illustrates a 42V power supply system using a bidirectional DC / DC converter,

3 shows a power supply system consisting of a combined start-generator (ISG), a car battery, an inverter and an engine,

4 shows a circuit diagram of the power supply system,

5 shows current i _a , i _b and i _c waveforms when switches Q ₂ , Q ₄ and Q ₆ are opened and closed at the same time with a constant period T while the switches Q ₁ , Q ₃ and Q ₅ are open. Shows an example of

6 shows the currents i _a , i _b when the switches Q ₂ , Q ₄ and Q ₆ are opened and closed with a time difference of 1/3 cycle with the switches Q ₁ , Q ₃ and Q ₅ open (off). shows an example of an i _o current waveform that is i _c and its sum,

7 shows current i _a , i _b and i _c waveforms when the switches Q ₁ , Q ₃ and Q ₅ are opened and closed at the same time with a constant period T while the switches Q ₂ , Q ₄ and Q ₆ are open (off). Shows an example of

8 shows the currents i _a , i _b when the switches Q ₁ , Q ₃ and Q ₅ are opened and closed with a time difference of 1/3 cycle with the switches Q ₂ , Q ₄ and Q ₆ open (off). , i _c and an i _o current waveform that is a sum thereof are shown.

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

1: Neutral point of three-phase AC winding of ISG of automobile

2: negative terminal of inverter connecting ISG and automotive battery

3: positive terminal of inverter connecting ISG and car battery

4: ISG of the car

5: Inverter for connecting ISG and car battery

Claims (23)

42V power supply system When the 42V battery, which is the power source of the vehicle, is discharged, the neutral point of the three-phase AC winding of the integrated starter and generator (ISG) of the 42V power supply system vehicle to charge the 42V battery. ; Connecting a 14V battery of a 14V power supply system vehicle between the combined start-generator and a DC link of an inverter connecting the 42V battery of the vehicle to charge the 42V battery. The method of claim 1 wherein the DC link is a negative terminal. delete The switch according to claim 2, wherein the switch is located between the winding of each phase of the three-phase AC winding and the positive terminal of the inverter with the 14V battery connected between the neutral point and the negative terminal of the inverter. In an open state, charging the 42V battery by periodically opening and closing switches located between each phase winding of the three-phase AC winding and the negative terminal of the inverter. delete The method of claim 1 wherein the DC link is a positive terminal. delete 7. The switch according to claim 6, wherein the switches located between the winding of each phase of the three-phase AC winding and the negative terminal of the inverter are open with the 14V battery connected between the neutral point and the positive terminal of the inverter. (off) charging the 42V battery by periodically opening and closing switches located between the winding of each phase of the three-phase AC winding and the positive terminal of the inverter. delete 9. A method according to claim 4 or 8, wherein the switches are simultaneously opened and closed at periodic opening and closing. 9. The method of claim 4 or 8, wherein the switches are opened and closed at regular intervals from each other. 12. The method of claim 11, wherein the regular time difference is 1/3 of a switch opening / closing period. 42V power supply system A power supply for supplying 42V power to a car. Including a combined starter-generator, inverter, and automotive 42V battery, A neutral point of the three-phase alternating current winding of the composite start-up generator; In order to connect a 14V battery of a 14V power supply system vehicle between DC links of the inverter, a terminal connected to the neutral point is provided outside of the composite start-generator, The inverter is interposed between the complex start-generator and the 42V battery to convert AC power of the complex start-generator to DC power, or convert DC power of the 42V battery to AC power, A switch and a diode are provided between the winding of each phase of the three-phase alternating winding of the generator and the DC link of the inverter, The 14V battery of the 14V power supply system vehicle is connected between the terminal provided outside the composite start-generator and the DC link of the inverter, and the switch is controlled to charge the 42V battery or the 14V battery. There is a power supply. 15. The power supply of claim 13, wherein the DC link is a negative terminal or a positive terminal. delete 14V power supply system The neutral point of the three-phase AC winding of the composite start-generator (ISG) of the vehicle 42V power supply system to charge the 14V battery when the 14V battery, which is the power source of the vehicle is discharged; Connecting the 14V battery of the 14V power supply system vehicle between the combined start-generator and the DC link of the inverter connecting the 42V battery of the vehicle to charge the 14V battery. 17. The method of claim 16, wherein the DC link is a negative terminal. 18. The switch according to claim 17, wherein the switches located between the winding of each phase of the three-phase AC winding and the negative terminal of the inverter are open with the 14V battery connected between the neutral point and the negative terminal of the inverter. (off) charging the 14V battery by periodically opening and closing switches located between the winding of each phase of the three-phase AC winding and the positive terminal of the inverter. 17. The method of claim 16, wherein the DC link is a positive terminal. 20. The switch according to claim 19, wherein the switches located between the winding of each phase of the three-phase AC winding and the positive terminal of the inverter are open with the 14V battery connected between the neutral point and the positive terminal of the inverter. (off) charging the 14V battery by periodically opening and closing switches located between each phase winding of the three-phase AC winding and the negative terminal of the inverter. 21. The method of claim 18 or 20, wherein the switches are simultaneously opened and closed at periodic opening and closing. 21. The method according to claim 18 or 20, wherein the switches are opened and closed at regular intervals from each other. 23. The method of claim 22, wherein the regular time difference is 1/3 of a switch opening / closing period.