JP2015030335A - Load drive system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a load drive system capable of improving the reduction in power consumption by effectively using electrical energy obtained by thermoelectric conversion.SOLUTION: A load drive system in which an inverter 132 mounted in an electric vehicle or a hybrid vehicle drives a load 20 such as a motor for vehicle driving, comprises: a main battery 11 connected to the inverter 132; a thermoelectric conversion element 2 that converts thermal energy generated from a semiconductor switch in the inverter 132 to electrical energy; auxiliary batteries 4A and 4B charged with the generated electricity; and a power adjustment circuit 131 adjusting a ratio of the electricity supplied from the main battery 11 to that supplied from the auxiliary batteries 4A and 4B. If the electricity supplied from the auxiliary batteries 4A and 4B is insufficient for electricity consumed by the load 20, the electricity is supplied from the main battery 11 to compensate for insufficiency.

Description

  The present invention relates to a load drive system that drives a load by a semiconductor power converter, and for example, to reduce power consumption of a main battery when a vehicle drive motor is driven by an inverter mounted on an electric vehicle or a hybrid vehicle. Is related to the technology.

As is well known, an inverter performs power conversion by turning on and off semiconductor switches such as IGBTs and MOSFETs, and generates heat due to steady loss and switching loss of the semiconductor switches.
Here, Patent Document 1 describes a conventional technique for adjusting the temperature of a battery unit mounted on an electric vehicle using heat generated from an inverter.
On the other hand, in Patent Document 2, in a projector apparatus including a light source unit such as a high-pressure mercury lamp, thermal energy generated by the light source unit is converted into electric energy by the Seebeck effect, and a cooling fan is operated using this electric energy. Discloses a technique for cooling the light source unit.

FIG. 3 is a block diagram showing a circuit configuration of the prior art described in Patent Document 2, where 100 is a thermoelectric module unit that converts thermal energy of a light source unit (not shown) into electrical energy, and 200 is a power system circuit. A substrate, 201 is a power supply circuit to which AC power is supplied, 202 is a voltage stabilization circuit such as a DC-DC converter that stabilizes the output voltage of the thermoelectric module unit 100, and 203 is an output of the power supply circuit 201 and a voltage stabilization circuit 202. The power adding circuit 300 adds the output of the power, and a cooling fan 300 is operated by the output of the power adding circuit 203 to cool the light source unit.
According to this prior art, the electric energy obtained by converting the heat energy of the light source unit can be used as a part of the driving power of the cooling fan 300, and the power consumption of the projector device can be reduced. .

JP 2008-108509 A (paragraphs [0025] to [0030], FIG. 1, FIG. 2, FIG. 4, etc.) JP 2006-148410 A (paragraphs [0109] to [0112], FIG. 6 and the like)

  In the prior art shown in FIG. 3, the thermoelectric module 100 continues to generate power due to the residual heat of the light source unit and rotates the cooling fan 300 even after the projector apparatus is turned off. However, even after the light source has been cooled to some extent and has reached a temperature at which it no longer needs to be cooled (a temperature at which there is no problem for safety even if it has a certain amount of heat, it can be left to natural cooling). The cooling fan 300 may continue to be operated with 100 generated power, and as a result, there is a problem that electric energy is wasted.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a load driving system in which power consumption is further reduced by effectively using electric energy obtained by thermoelectric conversion.

In order to solve the above-mentioned problem, the invention according to claim 1 relates to a load driving system for driving a load using electric power generated by a switching operation of a semiconductor switch in a semiconductor power converter. A main battery connected to the battery, a thermoelectric conversion element that converts thermal energy generated from the semiconductor power converter into electric energy, a plurality of auxiliary batteries that are charged using the power generated by the thermoelectric conversion element, and the main battery Power adjusting means for adjusting the ratio of the supplied power to the power supplied from the auxiliary battery and supplying the adjusted power to the semiconductor power converter.
In the present invention, when the power consumption of the load is insufficient with the power supplied from the auxiliary battery, the insufficient power is supplied from the main battery.

In addition, as described in claim 2, while some of the auxiliary batteries are being charged with the generated power of the thermoelectric conversion element, the other auxiliary batteries are discharged and the power adjustment means supplies power. It is desirable to supply
According to a third aspect of the present invention, it is desirable to provide a control means such as a microcomputer for monitoring the states of a plurality of auxiliary batteries and controlling the auxiliary batteries to be charged or discharged according to the states.
Furthermore, as described in claim 4, the load drive system according to the present invention can be applied to an electric vehicle, a hybrid vehicle, etc., and the thermoelectric conversion element converts the heat energy generated from the semiconductor switch in the inverter into the electric energy. However, it is preferable to use this electric energy for driving power of a load including a vehicle driving motor.

  According to the present invention, the auxiliary battery is charged using electrical energy obtained by thermoelectric conversion, and the power is preferentially used to drive a load such as a vehicle drive motor, thereby reducing the power consumption of the main battery. In addition, a highly efficient load drive system can be provided.

It is a block diagram which shows the whole structure of embodiment of this invention. It is a conceptual diagram which shows the installation state of the thermoelectric conversion element in embodiment of this invention. It is a block diagram which shows the circuit structure of a prior art.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing the overall configuration of this embodiment, which is a load drive system mounted on an electric vehicle or a hybrid vehicle, and includes a motor for driving a vehicle and the like by an inverter using the power of an on-vehicle battery. 1 shows a system driving a load.

  In FIG. 1, the output voltage of the main battery 11 is input to a stabilized power supply circuit 12 such as a DC-DC converter and converted into a DC voltage having a constant magnitude. The output voltage of the stabilized power circuit 12 is input to the power adjustment circuit 131 in the power control circuit 13 together with the output voltage of the stabilized power circuit 5 described later.

Power conditioning circuit 131 has a function of outputting to the inverter 132 by adjusting the ratio of DC power input from the two systems, the control signal SC ₁₃ from the microcomputer 1 to be described later, from the regulated power supply circuit 5 The power supply of the load 20 is used to the maximum, and the shortage of the power consumption of the load 20 is compensated by the power supply from the stabilized power supply circuit 12. For example, when the power consumption of the load 20 is less than the power supplied by the stabilized power circuit 5, the power supplied by the stabilized power circuit 12 on the main battery 11 side is not used.

The inverter 132 converts the DC power input from the power adjustment circuit 131 into AC power by a switching operation of a semiconductor switch (in this embodiment, IGBT), and supplies the AC power to the load 20 including a vehicle driving motor.
Here, it goes without saying that a MOSFET, a power bipolar transistor or the like can be used as the semiconductor switch constituting the inverter 132.

On the other hand, 2 is a thermoelectric conversion element that converts thermal energy into electrical energy. This thermoelectric conversion element 2 utilizes two Seebeck effects in which two types of metals or P-type and N-type semiconductors are joined and a voltage is generated according to the temperature difference between these joints.
The thermoelectric conversion element 2 is arranged at a position where the heat of the IGBT in the inverter 132 is reliably conducted. FIG. 2 is a conceptual diagram of the thermoelectric conversion element 2 attached to the IGBT 6 together with the radiation fins 7. As is well known, the heat radiating fins 7 are for releasing excess heat of the IGBT 6 into the atmosphere in order to keep the temperature of the IGBT 6 within the allowable operating temperature range.
The IGBT 6 is modularized by bridge-connecting a plurality of IGBT elements.

  Returning to FIG. 1, the electric power generated by the thermoelectric conversion element 2 is input to the charge control circuit 3, and the output side includes the first switch SW1, the first auxiliary battery 4A, and the second switch SW2. A series circuit and a series circuit of the third switch SW3, the second auxiliary battery 4B, and the fourth switch SW4 are connected in parallel. The parallel connection point of these two series circuits (the connection point between the switches SW2 and SW4) is connected to a stabilized power supply circuit 5 such as a DC-DC converter, and the output voltage is input to the power adjustment circuit 131. .

Reference numeral 1 denotes a microcomputer that comprehensively controls the entire load drive system. The microcomputer 1 may be provided exclusively, or an operation control microcomputer or the like that is already installed in an electric vehicle or the like may be used.
The microcomputer 1 receives battery status signals ST _4A and ST _4B from the first and second auxiliary batteries 4A and 4B, and switches control for turning on or off the first to fourth switches SW1 to SW4. Signals C _{1 to} C ₄ are output.
Here, the battery state signals ST _4A and ST _4B are information indicating electrical states such as overcharge, overdischarge, full charge, and capacity based on the voltage and temperature of each auxiliary battery 4A and 4B.

Further, communication signals SC ₅ and SC ₁₂ are transmitted and received between the microcomputer 1 and the stabilized power supply circuits 5 and 12 via a communication interface. A communication signal SC ₃ is transmitted / received between the microcomputer 1 and the charge control circuit 3, and a communication signal SC ₁₃ is transmitted / received between the microcomputer 1 and the power control circuit 13 via the communication interface. .

Communication signals SC ₅ and SC ₁₂ transmitted and received between the microcomputer 1 and the stabilized power supply circuits 5 and 12 are information such as power supply voltage and current supplied to the power adjustment circuit 131 by the power supply circuits 5 and 12, respectively. Is included. The communication signal SC ₃ transmitted / received between the microcomputer 1 and the charge control circuit 3 includes information such as the charge voltage, charge current, and charge elapsed time for the auxiliary batteries 4A and 4B. The communication signal SC ₁₃ transmitted / received between the microcomputer 1 and the power control circuit 13 is supplied to the power adjustment circuit 131 from the power supplied to the load 20 by the inverter 132 and from each of the power supply circuits 5 and 12. It contains information such as the amount of power and its proportion.

Next, the operation of this embodiment will be described.
Now, it is assumed that the inverter 132 performs power conversion using the power of the main battery 11 or the auxiliary batteries 4A and 4B and supplies power to the load 20. At this time, heat generated by steady loss or switching loss of the IGBT 6 is converted into electric energy by the thermoelectric conversion element 2, and a predetermined charging voltage and charging current are generated by the charging control circuit 3.

The microcomputer 1, a battery state signal _ST 4A, first on the basis of the _{ST 4B,} the second auxiliary battery 4A, always monitors the state of 4B, the charge control circuit 3 by the control signal SC ₃ according to the state While controlling, the switch control signals C _{1 to} C ₄ are generated and the switches SW ₁ to SW ₄ are turned on or off so as to charge one auxiliary battery and discharge the other auxiliary battery. The state of FIG. 1 is a state in which the switches SW ₁ and SW ₄ are turned on and the switches SW ₂ and SW ₃ are turned off in order to charge the first auxiliary battery 4A and discharge the second auxiliary battery 4B. .

As is well known, when a battery is operated in an overdischarged state or an overcharged state, its life is shortened, and in some cases, an accident such as ignition or explosion may occur. Therefore, the microcomputer 1 selects an auxiliary battery to be charged or discharged according to the state of the auxiliary batteries 4A and 4B, and controls the switches SW _{1 to} SW _{4 according} to an on / off pattern as described below. did.

For example, when the auxiliary battery 4A is fully charged and the auxiliary battery 4B needs to be charged, the switches SW ₁ and SW ₄ are turned off and the switches SW ₂ and SW ₃ are turned on to discharge the auxiliary battery 4A. The auxiliary battery 4B is charged.
On the contrary, when the auxiliary battery 4B needs to be fully charged and the auxiliary battery 4A needs to be charged, the switches SW ₁ and SW ₄ are turned on as shown in FIG. 1 and the switches SW ₂ and SW ₃ are turned on. Turn off.

When both of the auxiliary batteries 4A and 4B need to be charged, either one of the auxiliary batteries is charged first, and when the amount of charge reaches a predetermined value, the auxiliary battery is discharged and the other auxiliary battery is The switches SW ₁ to SW ₄ are controlled so as to charge, and thereafter, charging and discharging are alternately repeated.
Further, when both of the auxiliary batteries 4A and 4B are fully charged, both the switches SW ₁ and SW ₃ are turned off to prevent overcharging, and _{one of} the switches SW ₂ and SW ₄ is turned on. Discharge the auxiliary battery.
As described above, overcharging causes the life and ignition of the auxiliary batteries 4A and 4B, and the power generated by the thermoelectric conversion element 2 cannot be used effectively, causing a reduction in the usage efficiency of the auxiliary battery. . Therefore, the capacity of the auxiliary batteries 4A and 4B can be determined in consideration of the balance between the power consumption of the load 20 and the generated power of the thermoelectric conversion element 2 so that the auxiliary batteries 4A and 4B are not fully charged at the same time. is necessary.

  As described above, in the present embodiment, the auxiliary battery is selectively charged using the generated power of the thermoelectric conversion element 2 and the load 20 such as a vehicle driving motor is driven using the discharged power preferentially. To do. Therefore, it is possible to realize a highly efficient load driving system that effectively uses thermal energy to reduce the power consumption of the main battery 11 and improve the so-called power consumption.

In the above-described embodiment, the case where the thermal energy generated by the IGBT 6 of the inverter 132 is converted into electrical energy by the thermoelectric conversion element 2 has been described. However, the heat energy generated from another heat generating unit, for example, a motor as the load 20 is converted into electrical energy. By converting to energy and reusing, the power consumption can be improved by suppressing the power consumption of the main battery 11 as described above. In addition, the number of auxiliary batteries is not limited to two as in the embodiment, and if it is acceptable from the viewpoint of in-vehicle space, weight, cost, etc., more auxiliary batteries are mounted and used separately for charging and discharging. May be.
Furthermore, when the generated power of the thermoelectric conversion element 2 exceeds the power consumption of the load 20, the main battery 11 may be charged using surplus power.

  The present invention is not limited to a system that drives a load such as a vehicle driving motor of an electric vehicle or a hybrid vehicle by an inverter, but operates various semiconductor power converters such as a converter and a chopper using the power of a battery, and outputs thereof Therefore, the present invention can be used for various load driving systems that drive a load.

1: Microcomputer 2: Thermoelectric conversion element 3: Charge control circuit 4A, 4B: Auxiliary battery 5: Stabilized power supply circuit 6: IGBT
7: radiation fin 11: Main Battery 12: stabilized power supply circuit 13: the power control circuit 131: power conditioning circuit 132: Inverter 20: load _{SW 1, SW 2, SW 3} , SW 4: switch _{C 1, C} 2, C ₃ , C ₄ : Switch control signals ST _4A , ST _4B : Battery status signals SC ₃ , SC ₅ , SC ₁₂ , SC ₁₃ : Communication signals

Claims (4)

In a load driving system for driving a load using power generated by a switching operation of a semiconductor switch in a semiconductor power converter,
A main battery connected to the semiconductor power converter;
A thermoelectric conversion element that converts thermal energy generated from the semiconductor power converter into electrical energy;
A plurality of auxiliary batteries to be charged using the power generated by the thermoelectric conversion elements;
Power adjusting means for adjusting the ratio of the power supplied from the main battery and the power supplied from the auxiliary battery to supply to the semiconductor power converter;
With
A load driving system characterized in that when the power consumption of the load is insufficient with the power supplied from the auxiliary battery, a shortage of power is supplied from the main battery. The load drive system according to claim 1,
While charging some of the plurality of auxiliary batteries with the generated electric power of the thermoelectric conversion element, the other auxiliary batteries are discharged to supply electric power to the power adjusting means. Load drive system. In the load drive system according to claim 2,
A load driving system comprising: a control unit that monitors the states of the plurality of auxiliary batteries and controls the auxiliary batteries to be charged or discharged according to the states. The load drive system according to claim 1,
The load drive system is a system mounted on an automobile,
A load drive comprising: a thermoelectric conversion element for converting thermal energy generated from the semiconductor switch in an inverter as the semiconductor power converter into electrical energy; and the load includes at least a motor for driving a vehicle. system.

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