JPH0421326A - Voltage converter - Google Patents

Abstract

PURPOSE:To enhance the efficiency of a voltage conversion by connecting a plurality of cells for generating equal voltages in series, providing switching units corresponding to the cells, controlling them by a controller, and switching to output the voltages of the cells to an output terminal. CONSTITUTION:A controller 4 turns ON one switching unit 3a, turns OFF the other switching unit 3b or vice versa. When the unit 3a is ON, the voltage of a cell 2a is output from an output terminal as a lower voltage. On the contrary, when the unit 2b is ON, the voltage of the cell 2b is output. Thus, for example, it is repeated at a period of 40msec, thereby outputting a voltage of 1/2 of a power source voltage to be applied to a motor 1 from an output terminal 10 as a lower voltage. The voltages of the cells 2a, 2b are output without electric conversion to obtain the low voltage and hence to reduce power loss generated upon conversion of the voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to a voltage converter used to create a low power supply voltage for driving auxiliary equipment from a high power supply voltage for driving an electric motor or the like.

Conventional technology The voltage of the power supply for driving the electric motor, which is the running power of electric vehicles, is high at 48 to 120V, but the power supply voltage of most auxiliary equipment currently on the market for internal combustion vehicles is 12V, and 24V.
Only a few types of V are commercially available for use in diesel engines.

Therefore, these auxiliary machines cannot be used in electric vehicles whose motors are driven by a high power supply voltage of 48 to 120V.

Therefore, it is conceivable to generate the power supply voltage of the motor by connecting a plurality of batteries in series, and to generate the lower power supply voltage from some of the batteries.

It is also possible to create a power supply voltage for a motor from a series circuit of a plurality of batteries and also to create a power supply voltage for driving auxiliary equipment using a DC-DC converter, and this is often used in practice.

Problems to be Solved by the Invention By the way, a voltage converter that creates a low power supply voltage for driving auxiliary equipment from some of the batteries connected in series has different power consumption depending on the battery, and the capacity of the battery varies. There is a problem that the battery life becomes unbalanced and the life of the entire battery connected in series is shortened. Therefore, it is not actually used.

Further, a voltage converter that uses a DC-DC converter to generate a low power supply voltage for auxiliary equipment has the advantage that power can be taken out equally from each battery. However, since voltage conversion is performed by converting a high DC voltage into a pulsating current, transforming it using a transformer, and then obtaining a low DC voltage, there is a problem in that the efficiency of voltage conversion is as low as 80% or less. This is a factor that shortens battery life and cannot be ignored.

The present invention has been made to solve the above-mentioned problems, and it is possible to obtain a low power supply voltage by equally extracting power from a plurality of batteries connected in series, and to improve the efficiency of voltage conversion. purpose.

Means for Solving the Problems As a means for solving the above problems, the voltage converter according to the present invention has a plurality of voltage converters that generate the same voltage, as shown in the embodiments in FIGS. 1 to 3. Batteries 2a and 2b are connected in series, and switching parts 3a and 3b are provided corresponding to each battery to take out the voltage of batteries 2a and 2b to an output terminal, and the switching parts 3a,
3b is controlled by the control unit 4 to control each battery 2a, 2.
It is characterized in that the voltage of b is switched to the output terminal lO and taken out.

For production According to the voltage converter of the invention, each battery 2a.

Since the voltage of battery 2b is turned off and switched by FFA3a, 3b and taken out to the output terminal 10 to create a low N, original voltage, electric power can be taken out equally from each battery 2a, 2b.

Since the voltage of each battery 2a, 2b is taken out without being electrically converted, power loss due to conversion is reduced, and D
Conversion efficiency can be increased compared to when a C-DCC converter is used.

Example Next, the present invention shown in one figure will be described in detail.

FIG. 1 is a circuit block diagram conceptually showing an embodiment of a voltage converter according to the present invention.

In the drawing, 1 is an electric motor used to drive the electric vehicle, and 2a and 2b are batteries for driving the electric 1ml, which generate the same DC voltage and are connected in series. A power supply voltage created by a series circuit of batteries 2a and 2b is applied to an electric motor l.

In the figure, 3a is a switching section provided between the battery 2a and the output terminal IO, and 3b is a switching section provided between the battery 2b and the output terminal IO.

In the figure, 4 is a control section that controls the switching sections 3a and 3b.

This voltage converter always requires two batteries 2 for the electric 1111.
A voltage that is the sum of voltages a and 2b is applied, and output terminal 1
0, the voltage of the battery 2a and the voltage of the battery 2b are taken out alternately. Specifically, the control section 4
turns on the one switching section 3a, and turns on the other switching section 3a.
b is turned off, or conversely, the switching section 3b is turned on and the switching section 3a is turned off. When the switching unit 3a is in the on state, the voltage of the battery 2a is output from the output terminal as the lower power supply voltage. Conversely, when the switching section 3b is in the on state, the voltage of the battery 2b is output. By repeating this process of alternately outputting the voltage of the battery 2a and the voltage of the battery 2b, for example, with a cycle of 40 m5 e c, a voltage that is half of the power supply voltage applied to the electric motor Ial is applied to the lower power supply voltage. It can be output from the output terminal 10 as .

According to this voltage converter, by making the periods in which the switching parts 3a and 3b are on equal in each cycle, the battery 2a
Power can be taken out equally from 2b and 2b. By taking out the voltage of each battery 2a, 2b without electrically converting it, a low power supply voltage is obtained, so that less power loss occurs due to voltage conversion. Specifically, the switching unit 2a.

The only loss is the power consumed by the semiconductor 2b and the switching control section. Therefore, it is possible to increase the conversion efficiency compared to a voltage converter that converts voltage using a DC-DC converter. can. Specifically, the conversion efficiency can be increased to 95% or more.

FIG. 2A is a circuit diagram specifically showing the configuration of the voltage converter shown in FIG. 1.

In this circuit diagram, the switching section 3a is composed of field effect transistors FET1 and FET2. Specifically, the transistor FET 1 is connected between the anode of the battery 2a and the positive output terminal 10, and the transistor FE
T2 is connected between the cathode of the battery 2a and the negative output terminal IO.

Further, the switching section 3b is composed of field effect transistors FET3 and FET4. Specifically, the transistor FET3 connects the anode of the battery 2b and the positive output terminal IO.
The transistor FET4 is connected between the cathode of the battery 2b and the negative output terminal 10.

Control of the switching units 3a and 3b by the control unit 4 is as follows:
This is done by photocouplers 1 and 2.

Specifically, the control signal A is transmitted via the photocoupler 1 to the gates of the field effect transistors FETI and FET2 of the switching section 3a. Also, the control signal B is applied to the photocoupler 2.
is transmitted to the gates of field effect transistors FET3 and FET4 of the switching section 3b.

Note that R in the figure is a bias resistance for FETs 1 to 4.

FIG. 2B basically has the same configuration as the circuit diagram in FIG. 2A, but a diode 11 is used to cancel the reverse current phenomenon of the field effect transistors FETs 1 to 4. This shows a circuit diagram with the installed. This can prevent short circuits of the battery.

Figure w43 is a time chart showing the operation of the voltage converter shown in Figure 2A.

Other Embodiments In addition, the embodiment shown in "-" is a series-connected battery 2a,
The number of b is two. Therefore, if the voltage of each battery is 24V, you will get 48V as the voltage to drive the motor l,
24V can be obtained as a voltage for driving auxiliary equipment. However, the number of batteries connected in series is not necessarily 2.
The number of batteries is not limited to three or more, and the number of switching units can also be three or more accordingly.

For example, if the number of batteries and switching parts is set to three,
It becomes possible to obtain a voltage of 72v and a voltage of 24v.

As described above, the present invention can be implemented in various ways.

Effects of the present invention As described above, according to the voltage converter of the present invention, the voltage of each battery 2a, 2b is controlled by the switching unit 3a.

3b switches to take out a low power supply voltage, so power can be taken out equally from each battery 2a and 2b. The pond life can be increased.

In addition, since the voltage of each battery 2a, 2b is taken out without being electrically converted, power loss due to conversion is reduced, and DC
- Conversion efficiency can be increased compared to when a DC converter is used.

Furthermore, the higher DC voltage and the lower DC voltage can be easily set to the required values depending on the voltage of the batteries 2a, 2b used, the number of batteries used, and the number of switching units 3a, 3b. Become. Therefore, it is easily possible to use commercially available auxiliary equipment.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram conceptually showing one embodiment of the present invention, FIGS. 2A and B are different circuit diagrams embodying the voltage converter shown in FIG. 1, and FIG. 3 is a time chart showing the operation of the voltage converter shown in FIG. 2. b...Battery b...Switching section 4...Control section 0...Output terminal

Claims (1)

[Scope of Claims] [1] A plurality of batteries that generate the same voltage are connected in series, and a switching unit for extracting the battery voltage to an output terminal is provided corresponding to each battery; A voltage converter characterized in that each switching section is controlled by a control section to switch and output the voltage of each of the batteries to the output terminal.