JPH118910A - Power supply equipment for hybrid electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply equipment for a hybrid electric vehicle which realized a simple circuit configuration reverse power transmission from an auxiliary battery side to the side of a motor for starting up an engine. SOLUTION: A main battery 1 of a hybrid electric vehicle charges and auxiliary battery 6 through DC/DC converters 2-4. A high-voltage circuit section 2 conducts an inverter operation for supplying AC current to a coil 31 of a large number of turns of a transformer 3, when power is supplied from the main battery 1 to the auxiliary battery 6, and conducts a rectifying operation when power is supplied from the auxiliary battery 6 to the main battery 1. A low- voltage circuit section 4 conducts a rectifying operation, when power is supplied from the main battery 1 to the auxiliary battery 6 and conducts an inverter operation for supplying AC current to coils 32, 33 or the side of the transformer 3 with a small number of turns of, when power is supplied from the auxiliary battery 6 to the main battery 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply for a hybrid electric vehicle.

[0002]

2. Description of the Related Art In a conventional hybrid electric vehicle in which power is supplied from a generator driven by an internal combustion engine to a main battery and a traveling motor, the internal combustion engine is powered by an engine starting motor supplied from the main battery. The motor is started, and the above-described generator or the like can be used as a motor for the start.

Japanese Patent Application Laid-Open No. 62173901 discloses a DC / DC converter for supplying electric power to a traveling motor for an electric vehicle (hereinafter also referred to as a main battery).
An electric vehicle (hereinafter, referred to as an auxiliary battery) which supplies power to a battery for driving the auxiliary machine (hereinafter, also referred to as an auxiliary battery) via a DC / DC converter (hereinafter, also referred to as an auxiliary machine DC / DC converter).
Type electric vehicle). In this type of auxiliary battery-powered electric vehicle, a high voltage can be supplied to the traveling motor much more than an auxiliary device which is normally supplied at a low voltage, so that effects such as loss reduction and downsizing of equipment can be obtained. On the other hand, there is an advantage that a power supply voltage with small voltage fluctuation can be applied to the auxiliary machine.

[0004]

However, in the above-mentioned hybrid electric vehicle, the remaining amount of the main battery is large in principle in order to drive the traveling energy to the traveling motor. It is conceivable that the engine cannot be started because the remaining amount of the main battery, that is, the dischargeable amp hour is insufficient.

In this case, in a hybrid electric vehicle having the accessory battery and the accessory DC / DC converter, power is supplied from the accessory battery to the engine starting motor even when the remaining amount of the main battery is insufficient. It is conceivable to start the engine. That is, the auxiliary battery
The power is always stored at a certain voltage level to supply power to various accessories, and in the event of an emergency in which the engine cannot be started with the main battery, priority is given to supplying stable voltage to the accessories. It is important to start the engine first, and if the engine can be started, the recharging of the auxiliary battery should be able to be quickly realized.

However, in order to drive the traveling motor by the auxiliary battery as described above, a new boosting is performed by increasing the output voltage of the auxiliary battery, which is low, and applying it to the traveling motor. A DC / DC converter has to be additionally provided, which causes a problem that the circuit configuration becomes complicated and the cost of the apparatus increases. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a power supply apparatus for a hybrid electric vehicle in which reverse power transmission from an auxiliary battery side to an engine starting motor side is realized with a simple circuit configuration. For that purpose.

[0007]

According to the first aspect of the present invention, the main battery of the hybrid electric vehicle is DC / DC.
The auxiliary battery is charged through the DC converter. In particular, in this configuration, the DC / DC converter includes a high voltage circuit on the main battery side, a transformer, and a low voltage circuit on the auxiliary battery side.

The high-voltage circuit uses a bidirectional switching element to perform a so-called inverter operation when power is supplied from the main battery to the auxiliary battery to supply an alternating current to the coil on the large number of turns of the transformer. When power is supplied from the auxiliary battery to the main battery, a so-called rectifying operation is performed. By using a bidirectional switching element, the low-voltage circuit performs a so-called rectifying operation when power is supplied from the main battery to the auxiliary battery, and performs a so-called inverter operation when power is supplied from the auxiliary battery to the main battery. Then, an alternating current is supplied to the coil on the side of the small number of turns of the transformer.

According to the present invention, the auxiliary battery is separately provided from the main battery, as in the prior art, so that a low-voltage DC voltage with little voltage fluctuation can be stably supplied to the auxiliary machine. Further, by using the bidirectional switching element, it is possible to realize a power supply device for a hybrid electric vehicle in which reverse power transmission from the auxiliary battery side to the engine starting motor side is realized with a simple circuit configuration.

According to the second aspect of the invention, since the traveling motor also functions as a generator in the first aspect, the configuration of the apparatus can be further simplified. As a circuit capable of switching between the inverter operation and the rectification operation, for example, a pair of small-winding-side coils are wound around a transformer, and the output from these small-winding-side coils is provided. The low-voltage AC voltage is full-wave rectified by a pair of bidirectional switching elements, and is smoothed by a reactor of a smoothing circuit.

When the main battery is charged from the auxiliary battery, the switching element is turned on and off so that the reactor is periodically energized by the auxiliary battery, and the full-wave rectifier circuit is synchronized with the switching element. The constituent switching elements are turned on alternately to generate a boosted AC voltage in the coil on the large number of turns of the transformer. In this way, reverse power transmission can be performed with a simple circuit configuration.

According to a fourth aspect of the present invention, in the configuration of the first or second aspect, both ends of the coil having the lower number of turns are connected to the auxiliary battery through a smoothing circuit including a reactor.
An H-bridge circuit connected to both ends of is provided. With this configuration, the boosted AC voltage can be applied to the coil on the side of the small number of turns of the transformer by controlling the conduction of the four switching elements forming the H-bridge circuit, and the circuit configuration can be simplified. it can.

According to a fifth aspect of the present invention, in the configuration according to any one of the first to fourth aspects, when the remaining amount of the auxiliary battery is detected as being insufficient, the DC / DC converter may be used. Since the bidirectional switching element is drive-controlled to supply power from the main battery to the auxiliary battery, the DC / DC converter and the like can be stopped when the auxiliary battery is sufficiently charged. Wasteful power consumption can be reduced.

According to a sixth aspect of the present invention, in the configuration of any one of the first to fifth aspects, a bidirectional DC / DC converter is further provided for detecting an insufficiency state of the main battery. Since the driving of the switching element is controlled to supply power from the auxiliary battery to the main battery, the DC / DC converter is used when the main battery is sufficiently charged.
Data and the like can be stopped, and unnecessary power consumption can be reduced.

According to a seventh aspect of the present invention, the bidirectional switching element of the DC / DC converter is provided only when the engine is started and the remaining amount of the main battery is insufficient. Since the drive is controlled to supply power from the auxiliary battery to the main battery, power transmission from the auxiliary battery to the main battery is performed even when the engine is not started, even when the remaining amount of the main battery is insufficient. Therefore, power can be steadily transmitted from the auxiliary battery to the main battery when the vehicle is stopped for a long period of time to prevent the auxiliary battery from being consumed.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a hybrid electric vehicle according to the present invention, a main battery supplies power to an engine starting motor to start an engine. As a motor for starting the engine, the main battery is driven by the engine to generate electric power.
Is generally used. A running motor can be used as the generator.

The bidirectional switching element may be configured by connecting a unidirectional switch such as a bipolar transistor and a diode conducting in the opposite direction in parallel. Preferred embodiments of the present invention will be described with reference to the following examples.

[0018]

【Example】

Embodiment 1 (Configuration) An embodiment of a power supply device for a hybrid electric vehicle according to the present invention will be described with reference to FIG.

This power supply device comprises a main battery 1, a high-voltage circuit 2, a transformer 3, a low-voltage circuit 4, a controller 5, and an auxiliary battery 6. The transformer 3 and the low-voltage circuit unit 4 constitute a bidirectional DC / DC converter according to the present invention. The main battery 1 is connected to a traveling motor 7 composed of a generator motor so as to be able to exchange electric power. The traveling motor 7 is mechanically coupled to wheels so as to be able to cut off transmission torque, and is also transmitted. It is mechanically coupled to the engine 8 so that the torque can be cut off. There are various types of mechanical connection between the traveling motor 7, the engine 8 and the wheels (not shown).
The description is omitted because it is not the gist of the present invention.

The high-voltage circuit section 2 comprises a so-called bidirectional bridge circuit, a first phase inverter circuit in which a high-side switch 21 and a low-side switch 22 each comprising an NMOS transistor are connected in series, and an NMOS transistor respectively. High side switch 23
And a second phase inverter circuit in which a low-side switch 24 is connected in series. A connection point between the switches 21 and 22 is connected to one end of a coil 31 on the large number of turns of the transformer 3, and the switches 23 and 24 are connected. Is connected to the other end of the coil 31 on the large number of turns of the transformer 3. The other ends of the high-side switches 21 and 23 are connected to a high end of the main battery 1, and the other ends of the low-side switches 22 and 24 are connected to a low end of the main battery 1. Reference numeral 25 denotes a capacitor for reducing ripple.

The transformer 3 has a pair of small-turn coils 32 and 33 wound in opposite directions together with the large-turn coil 31.
3 is connected to the lower end of the auxiliary battery-6. The low-voltage circuit unit 4 includes full-wave rectification switches 41 and 42 each including an NMOS transistor, and N
A switching element 43 composed of a MOS transistor;
It comprises a reactor 44 and a capacitor 45 for ripple reduction.

The other end of the coil 32 and the other end of the coil 33 are connected to the higher end of the auxiliary battery 6 through a full-wave rectification switch 41 and a reactor 44, and the switching element 43 is connected to the full-wave rectification switches 41 and 42. Are connected between the other ends. The capacitor 45 is connected in parallel with the auxiliary battery-6. Further, the switches 21 to 24 and 41 to 43 each composed of the above-mentioned NMOS transistor are connected in parallel with a diode for reverse conduction, and the cathode of each diode D is connected to the main battery-1 or the auxiliary machine. The high side and the anode of the battery 6 are connected to the low side. Note that these diodes D may be constituted by junction diodes inherent in each NMOS transistor. In this case, the P-well region of each NMOS transistor, that is, the semiconductor region immediately below the channel, is connected to the lower side of the main battery-1 or the auxiliary battery-6.

The controller 5 intermittently controls the switches 21 to 24 of the high voltage circuit 2 and the switches 41 to 43 of the low voltage circuit 4. The controller 5 has terminal voltages of the main battery 1 and the auxiliary battery 6 input from the outside,
Based on an auxiliary battery charge signal and a main battery charge signal input from an external controller (not shown),
The switches 21 to 24 and 41 to 43 are intermittently controlled.

(Operation) The operation of the above apparatus will be described below with reference to the flowchart of FIG. First, after the power-on reset operation, it is checked whether or not an auxiliary battery charge command signal from an external controller (not shown) for vehicle control is present (S100). The terminal voltage V2 is equal to a predetermined minimum threshold value VT.
It is checked whether it is less than 2 (S102). If V2 is not less than VT2, the process proceeds to S108.

On the other hand, if there is an auxiliary battery charge command signal or if the terminal voltage V2 is lower than the predetermined minimum threshold V
If it is less than T2, the DC / DC converter performs the normal power transmission described later, that is, the power transmission from the main battery-1 to the auxiliary battery-6 (S104), and thereafter, the voltage V2 of the auxiliary battery-6 becomes a predetermined value. It is checked whether or not the threshold value VT2 'has been reached (S106), and when it has reached, the process returns to S100.

In step S108, it is checked whether there is a main battery charge command signal from the vehicle control external controller (not shown). If not, the terminal voltage V1 of the main battery-1 is reduced to a predetermined minimum threshold value. It is checked whether it is less than VT1 (S110), and if V1 is more than VT1, S100.
Return. On the other hand, if there is a main battery charge command signal or if terminal voltage V1 is lower than predetermined minimum threshold value VT1, a reverse power transmission command to DC / DC converter 3, which will be described later, that is, auxiliary battery-6 To transmit power to the main battery-1 (S112). Thereafter, it is determined whether or not the voltage V1 of the main battery-1 has reached a predetermined threshold value VT1 '(S114). I do.

In the above configuration, each switch 21
24 to 41 to 43 can be constituted by bipolar transistors having diodes D connected in parallel, and the switching element 43 can be constituted by bipolar transistors without the diode D. (Normal Power Transmission) Hereinafter, the normal power transmission will be described.

In this normal power transmission, the switches 21 and 24 are turned on and the switches 22 and 23 are turned off, and the switches 21 and 24 are turned off in order to make the high-voltage circuit section 2 perform an inverter operation. The mode in which the switches 22 and 23 are turned on is alternately repeated at a constant cycle. of course,
The voltage V2 of the auxiliary battery 6 may be monitored, and the duty ratio of these switches 21 to 24 may be controlled according to the magnitude, that is, the remaining amount of the auxiliary battery 6.

Since the coils 32 and 33 are wound in opposite directions, their output terminals alternately become a positive potential and a negative potential when the lower end of the auxiliary battery 6 is set to 0V. When the output terminals of the coils 32 and 33 have a higher potential than the high-order terminal of the auxiliary battery, the auxiliary battery is connected through diodes and a reactor 44 connected in parallel to the switches 41 and 42.
6 is charged. The gate voltage when the switches 41 and 42 are cut off is sufficiently negative to cut off even if the output terminals of the coils 32 and 33 are at the above-mentioned negative potential.

Thus, the auxiliary battery 6 is charged by the ripple-free DC current through the smoothing circuit including the reactor 44 and the capacitor 45. In addition,
The switching element 43 is always shut off. (Reverse power transmission) Hereinafter, the reverse power transmission will be described.

In this reverse power transmission, the low voltage circuit section 4
It is necessary to perform the voltage raising operation to a level at which the output voltage of the coil 31 on the large number of turns of the transformer 3 can charge the main battery-1. More specifically, by intermittently switching the switching element 43 at a predetermined cycle,
When the switching element 43 is shut off, the switching element 43
A voltage higher than that of auxiliary battery 6 is periodically generated at a connection point between power supply and reactor 5.

When the switch (switching element) 41 is turned on at the timing when this high voltage is generated, that is, at the odd-numbered timing when the switching element 43 is shut off, and the switch 42 is turned off, the coil 31 causes the transformer 3 to move in one direction. The switch (switching element) 42 is turned on at the timing when the magnetic flux is formed and the high voltage is generated, that is, at the even-numbered timing when the switching element 43 is shut off.
Is interrupted, a magnetic flux is formed in the transformer 3 in the reverse direction by the coil 31, and a high AC voltage is generated in the coil 31 on the large number of turns of the transformer 3.

This AC voltage is full-wave rectified by the four bridges D of the high voltage circuit 2 to charge the main battery-1. Referring to FIG. 3, another embodiment of the present invention will be described with reference to the flowchart of FIG. In this embodiment, the contents of S108 of the first embodiment are changed as follows, and the flow of S110 of the first embodiment is changed.
The feature is that the position on the chart is changed.

That is, in this embodiment, it is determined whether or not a signal for starting the engine has been received from an external vehicle control controller (not shown) (S108). It is determined whether or not V1 is less than a predetermined minimum threshold value VT1 (S110).
Reverse power transmission from auxiliary battery -6 to main battery -1 is performed only when T1 is less than T1 and when the engine is started (S11).
2).

In this manner, unnecessary consumption of the auxiliary battery 6 due to reverse power transmission to the main battery 1 other than when the engine is started can be avoided, and a practically excellent effect can be obtained. Embodiment 3 Another embodiment will be described with reference to the circuit diagram of FIG.

This embodiment is different from the circuit of the first embodiment (see FIG. 1) in that the low-voltage circuit section 4 is changed to the low-voltage circuit section 4 'and the coil 33 of the transformer 3 on the small number of turns is omitted. Features. This low voltage circuit section 4 '
It has an H-bridge (full bridge) circuit composed of NPN bipolar transistors 91 to 94, and a diode D is connected in parallel to each of the transistors 91 to 94.

Hereinafter, the operation of the low voltage circuit section 4 'will be described. (Normal power transmission) In normal power transmission, full-wave rectification is performed by a diode bridge circuit including four diodes D, and a voltage smoothed by a smoothing circuit including the reactor 44 and the capacitor 45 is supplied to the auxiliary battery 6. Applied. (Reverse power transmission) In this reverse power transmission, it is necessary to operate the low-voltage circuit section 4 as an inverter and to increase the output voltage of the coil 31 on the large number of turns of the transformer 3 to a level at which the main battery 1 can be charged. is there.

More specifically, transistors 91 to 94
Are simultaneously conducted at a predetermined cycle instead of the switching element 43 of the first embodiment. Thereby, magnetic energy is stored in the reactor 44. As a result, the collector voltage of transistor 91 is boosted at the time of simultaneous shutoff of transistors 91-94. Therefore, at this time, the pair of transistors 91 and 94 is turned on, and the transistors 92 and 9 are turned on.
When the pair 3 is cut off, a current flows in one direction through the coil 32 on the side of the small number of turns of the transformer 3.

On the other hand, when these transistors 91 to 94 are simultaneously turned off, the pair of transistors 91 and 94 is turned off.
When the pair of transistors 92 and 93 is turned on, a current flows in the reverse direction through the coil 32 on the small number of turns of the transformer 3, thereby generating a boosted AC voltage in the coil 31 on the large number of turns of the transformer 3. The boosted AC voltage is full-wave rectified by the diode D of the high voltage circuit section 2.

In this way, reverse power transmission can be performed with a simple circuit configuration. In each of the above embodiments, boosting was performed during reverse power transmission. However, boosting is not necessarily required depending on the setting of design parameters. Further, boosting can be performed by another circuit. Furthermore, in each of the above embodiments, examples using MOSFETs and bipolar transistors have been described, but other voltage-driven semiconductor elements such as IGBTs may be used instead.

In the above embodiment, the rectification is performed using the diode D. However, based on the AC voltage waveform and current phase to be rectified, the MOSF which is a bidirectional switching element is used.
By controlling the switching of the ETs 21 to 24 and 41 to 42, rectification can be performed. For example, the potential difference between both ends of these MOSFETs may be monitored and the corresponding MOSFET may be turned on only during a period during which a rectified current can flow.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating a power supply device of a hybrid electric vehicle according to a first embodiment.

FIG. 2 is a flowchart showing the operation of the controller 5 of FIG.

FIG. 3 is a diagram illustrating a low-voltage circuit unit 4 at the time of reverse power transmission in the circuit of FIG. 1;
5 is a timing chart showing the operation of FIG.

FIG. 4 is a flowchart showing a second embodiment.

FIG. 5 is a circuit diagram showing a third embodiment.

[Explanation of symbols]

1 is a main battery, 2 is a high voltage circuit (a part of a DC / DC converter), 3 is a transformer (a part of a DC / DC converter), 4 is a low voltage circuit (a DC / DC converter). 5) a controller (detection means, power supply control means, engine start detection means), 6 an auxiliary battery, 7 a running motor also serving as a generator, 8 an engine (internal combustion engine) 2
1 to 24, 41 to 44 are switching elements, and 44 is a reactor.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H02M 3/28 H02M 3/28 HF

Claims (7)

[Claims] 1. A main battery, a traveling motor supplied from the main battery, an internal combustion engine, and a generator driven by the internal combustion engine to charge the main battery;
An auxiliary battery for supplying power to the auxiliary machine, which is lower in voltage than the main battery; and a DC / DC converter for supplying power from the main battery to the auxiliary battery. A transformer, and when power is supplied from the main battery to the auxiliary battery, a power supply current from the main battery is periodically inverted and supplied to a coil having a large number of turns of the transformer, and the auxiliary battery is supplied. And a high-voltage circuit unit having a bidirectional switching element for rectifying a high-voltage AC voltage output from the coil having a large number of turns when power is supplied from the auxiliary battery to the main battery. Sometimes the power supply current from the auxiliary battery is periodically inverted and supplied to the coil on the side of the small number of turns of the transformer,
A low-voltage circuit unit having a bidirectional switching element for rectifying a low-voltage AC voltage output from the coil on the small number of turns when power is supplied from the main battery to the auxiliary battery; Automotive power supply. 2. A power supply apparatus for a hybrid electric vehicle according to claim 1, wherein said traveling motor also functions as said generator. 3. The power supply device for a hybrid electric vehicle according to claim 1, further comprising: a pair of said small number-of-turn coils wound in opposite directions of said transformer; A rectifying bidirectional switching element for alternately rectifying a low-voltage AC voltage output from the small-number-of-turns coil when power is supplied from a battery to the auxiliary battery; A reactor interposed between the machine battery and
A power supply device for a hybrid electric vehicle, comprising: a switching element for intermittently intermittently intermitting a current flowing from the auxiliary battery to the reactor. 4. The power supply device for a hybrid electric vehicle according to claim 1, wherein the low-voltage circuit section connects both ends of the small-turn-side coil to both ends of the auxiliary battery through a smoothing circuit including a reactor. A power supply device for a hybrid electric vehicle, comprising an H-bridge circuit to be connected. 5. The power supply device for a hybrid electric vehicle according to claim 1, wherein a detecting means for detecting a state of the remaining amount of the auxiliary battery is insufficient, and a remaining amount of the auxiliary battery is insufficient. When the state is detected, the D
A power supply device for a hybrid electric vehicle, comprising: power supply control means for driving and controlling a bidirectional switching element of a C / DC converter to supply power from the main battery to the auxiliary battery. 6. A power supply device for a hybrid electric vehicle according to claim 1, wherein said detecting means detects a state of insufficient remaining amount of said main battery, and detects a state of insufficient remaining amount of said main battery. Sometimes said DC
Power supply control means for controlling the driving of the bidirectional switching element of the DC / DC converter to supply power from the auxiliary battery to the main battery. 7. A power supply device for a hybrid electric vehicle according to claim 6, further comprising engine start detection means for detecting engine start,
The power supply control means drives and controls the bidirectional switching element of the DC / DC converter to supply power from the auxiliary battery to the main battery when detecting the start of the engine when the remaining amount is insufficient. A power supply device for a hybrid electric vehicle.