JP4967868B2 - Hybrid vehicle drive apparatus and control method - Google Patents

Description

  The present invention relates to a hybrid vehicle drive apparatus and control method including an engine, an engine cooling system that cools the engine, an inverter, an inverter cooling system that cools the inverter, a switch element and a smoothing capacitor provided in the inverter.

  Conventionally, a hybrid vehicle that can travel using the driving force of an engine and a motor includes a converter that boosts the voltage of the main battery, and an inverter that converts the boosted power into three-phase alternating current to drive the motor. Is provided.

  Converters, inverters, and the like (hereinafter referred to as inverters) incorporate semiconductor switching elements such as IGBTs, smoothing film capacitors, aluminum electrolytic capacitors, and the like (hereinafter referred to as smoothing capacitors). The semiconductor switching element used may exceed the allowable temperature due to heat generated by energization with a large current, and the junction may be destroyed. Similarly, the temperature rises excessively, and the smoothing capacitor is adversely affected.

  Therefore, in order to prevent an excessive temperature rise of the inverter, the element temperature of the inverter circuit is detected by a temperature sensor provided in the vicinity of the inverter circuit, and when the detected temperature exceeds the allowable temperature, the output frequency of the inverter circuit is set. There is a technique for reducing the amount of heat generated by the semiconductor switching element. However, there is a heat conduction delay due to heat transfer resistance and heat capacity in the heat dissipation path from the semiconductor switching element to the temperature sensor. In some cases, the temperature exceeded the allowable value.

  Therefore, in Patent Document 1, when the temperature change rate (temperature change per unit time) continuously detected from the temperature sensor in the vicinity of the semiconductor switching element is higher than the predetermined value, the semiconductor switching element is energized. A technique is disclosed in which the temperature of the semiconductor switching element is controlled to be equal to or lower than a predetermined allowable temperature in spite of a temperature detection delay by increasing the current decrease rate.

JP 2000-83383 A

  However, the technique described above is a technique for a semiconductor switching element that is a heat generation source, and a device or a control for controlling the temperature to be equal to or lower than the allowable temperature of the smoothing capacitor has not been achieved. In addition, when the hybrid vehicle is idling and the motor generator continues to be driven by engine operation for battery charging, cooling by running wind is not performed, and the smoothing capacitor is affected by the heat generated by the inverter itself and the engine exhaust heat. The temperature may increase.

For example, if you are using the aluminum electrolytic capacitor to the smoothing capacitor, since the allowable temperature is about 105 degrees, but equal to or less than the allowable temperature in the outer peripheral portion of the smoothing capacitor, the permissible temperature inside by you continue power conversion This may cause deterioration of the smoothing capacitor.

  Accordingly, an object of the present invention is to provide a hybrid vehicle drive device and a control method that can prevent overheating of a smoothing capacitor in order to suppress a decrease in output performance of an inverter and exhibit stable performance.

In order to achieve the above object, a hybrid vehicle drive device according to the present invention is provided in an engine, an engine cooling system that cools the engine, an inverter, an inverter cooling system that cools the inverter, and the inverter. Inverter refrigerant temperature measuring means for measuring the refrigerant temperature of the inverter and engine refrigerant temperature measuring means for measuring the refrigerant temperature of the engine in a hybrid vehicle drive device including a switching element and a smoothing capacitor, a motor generator, and a battery An inverter output measuring means for measuring the inverter output, a low load time measuring means for measuring the idling duration in a situation where the vehicle is stopped and the engine is idling for charging the battery, and an initial temperature duration and Lee from values and low load time measuring means And temperature estimating means for estimating the temperature of the smoothing capacitor based on the exponential equation including converter refrigerant temperature and the engine coolant temperature and an inverter output, if the estimated temperature obtained by the temperature estimating means exceeds the allowable temperature, the inverter output Overheating prevention means for preventing overheating of the smoothing capacitor by performing any one or more of an output reduction operation for reducing and a cooling promotion operation for promoting cooling of the inverter cooling system.

Further, in the hybrid vehicle driving system according to the present invention, the temperature estimating means further vehicle stopped vehicle state, and, when the time idling is continued becomes a predetermined time or more, the offset value of the smoothing capacitor The estimated temperature is increased by adding to the temperature .

The control method for a hybrid vehicle drive device according to the present invention includes an engine, an engine cooling system for cooling the engine, an inverter, an inverter cooling system for cooling the inverter, a switching element provided in the inverter, and a smoothing capacitor. When a motor-generator, the control method of the hybrid vehicle drive system including a battery and an inverter coolant temperature measuring step of measuring the inverter coolant temperature, an engine coolant temperature measuring step of measuring the engine coolant temperature, an inverter output an inverter output measuring step of measuring, the vehicle is stopped vehicle state, and the low-load time measuring step of measuring the idling duration in situations where engine for battery charging is idling rotation, the initial temperature value and low load duration and inverter cold from the time measurement process If the temperature estimating step of estimating the temperature of the smoothing capacitor based on the exponential equation including temperature and the engine coolant temperature and the inverter output, the estimated temperature obtained by the temperature estimating step above the allowable temperature, reducing the inverter output And an overheating prevention step for preventing overheating of the smoothing capacitor by performing one or more of an output reduction operation and a cooling promotion operation for promoting cooling of the inverter cooling system.

Further, in the control method of the hybrid vehicle driving system according to the present invention, the temperature estimating step further, the vehicle is stopped vehicle state, and, when the time idling is continued becomes a predetermined time or more, the offset value The estimated temperature is raised by adding to the temperature of the smoothing capacitor .

  By using the present invention, there is an effect that it is possible to realize not only the temperature of the semiconductor switching element that is a heat generation source, but also control that makes the temperature of the smoothing capacitor equal to or lower than the allowable temperature.

  Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings.

  FIG. 1 is a schematic configuration of a hybrid vehicle 100 including an overheat protection ECU 23 that functions as an overheat protection device for a smoothing capacitor. One of the characteristic matters of the present invention is that control is performed not only for a semiconductor switch element that is a heat source of an inverter but also for a smoothing capacitor even if there is a detection delay of the temperature sensor, below a predetermined allowable temperature. Is to do.

  The hybrid vehicle 100 in FIG. 1 is roughly divided into a transmission system that transmits the rotational force of the engine 13, the motor generator 31, and the motor 32 to the wheels 15, an engine cooling system that uses cooling water as a refrigerant, and an inverter cooling system. And a control system for controlling these. The transmission system includes an engine 13, a motor generator 31, a motor 32, a planetary gear mechanism 14, a differential gear 16, and wheels 15, and the engine 13 and the motor connected to the planetary gear mechanism 14. The wheel 15 is rotated by the generator 31 and the motor 32. Here, the motor generator 31 is rotated by the engine 13 via the planetary gear mechanism 14 and also functions as a generator.

  The engine cooling system includes the engine radiator 11, the pump 62, the engine coolant passage 56, the coolant passage 13a provided in the engine 13, the temperature sensor 41, and the engine coolant in the order in which the coolant flows. A water passage 57. Similarly, the inverter cooling system includes the inverter radiator 10, the pump 61, the inverter cooling water passage 51, the cooling water passage 33 a provided in the inverter 33, and the inverter cooling water in the order in which the cooling water flows. A passage 52, a cooling water passage 34a provided in the inverter 34, a temperature sensor 43, an inverter cooling water passage 53, a cooling water passage 32a provided in the motor 32, and an inverter cooling water passage 54 A cooling water passage 31a provided in the motor generator 31 and an inverter cooling water passage 55 are provided.

  The control system includes a hybrid ECU 21 that controls the whole, an engine ECU 22 that controls the engine 13, a motor ECU 24 that controls the inverters 33 and 34, and the battery 35, an overheat protection ECU 23 that is one of the features of the present invention, have. The overheat protection ECU 23 is connected to a temperature sensor 41 that measures the engine water temperature, a temperature sensor 42 that measures the ambient temperature of the inverters 33 and 34, and a temperature sensor 43 that measures the inverter water temperature. Further, the overheat protection ECU 23 acquires various types of vehicle information from the hybrid ECU 21 and acquires output values of the inverters 33 and 34 from the motor ECU 24.

  FIG. 2 shows the configuration of the inverter 33, the battery 35, and the motor generator 31. The inverter 33 shown in FIG. 2 includes a large-capacity smoothing / capacitor 37a, a high-frequency removing snubber capacitor 37b, and a semiconductor switching element 36. The inverter 33 converts the DC power from the battery 35 into a U-phase, V-phase, and W-phase three-phase alternating current and outputs it to the motor generator 31, or converts the alternating current power generated by the motor generator 31 into direct current power. To charge the battery. Generally, since a smoothing capacitor 37a and a snubber capacitor 37b that smoothes a high-frequency signal are disposed in the vicinity of the semiconductor switching element 36 that is a heat generation source, special consideration is required for heat dissipation.

FIG. 3 shows the flow of the smoothing capacitor temperature calculation process, and FIG. 4 shows the time variation of the estimated smoothing capacitor temperature estimated by the heat protection ECU. Hybrid vehicle is a car stops, in a situation where the engine is idling rotation for battery charging, Fig. 1, Fig. 3, the flow of the processing will be described with reference to the formula shown below and FIG. In the figure, the smoothing capacitor is simply called a capacitor.

  The hybrid ECU 21 in FIG. 1 issues a command to the engine ECU 22 and the motor ECU 24 to charge the battery 35, and transmits the driving force of the engine 13 to the motor generator 31. Thereby, the driving force of the engine 13 is transmitted to the motor generator 31 by the planetary gear mechanism 14, and the motor generator 31 is driven to generate electric power. The generated AC power is converted into DC power by the inverter 33 and charges the battery 35. The capacitor temperature calculation process will be described below.

  In step S10 of FIG. 3, when it is detected that the hybrid vehicle is in an idle state, the process proceeds to step S12, and measurement of idling duration time is started. Next, in step S14, the capacitor temperature calculation process shown in Equation 1 and Equation 2 is executed. The capacitor temperature Tc can be expressed by an exponential function from Tao, which is the initial value of the ambient temperature Ta, to the saturation temperature A. T is a capacitor temperature rise time constant, and these relationships are shown in Equation 1.

Tc = A (1-e- ^{t / T} ) + Tao (Formula 1)

  Here, the saturation temperature A can be expressed by the ambient temperature Ta outside the capacitor, the engine water temperature Tew, the inverter water temperature Tiw, the inverter output Pi, and the coefficients α, β, γ. It is shown in Formula 2.

      A = Ta + αTew + βPi−γTiw (Formula 2)

  Here, the saturation temperature A and the coefficients α, β, and γ can be obtained by measuring the actual characteristics of the hybrid vehicle, and are referred to as compatible constants. This adaptation constant is a constant obtained as a combination of numerical values that are considered to be the best based on the actual measurement values of the experimental vehicle, including a capacitor and an experimental vehicle capable of actually measuring various temperatures. Here, the engine water temperature Tew, the inverter water temperature Tiw, and the inverter output Pi are recognized values that the overheat protection ECU 23 acquires from the temperature sensors 41, 42, and 43 and external devices, and steps are performed using these information. In S14, the capacitor temperature Tc is calculated.

  Next, in step S15, it is determined whether or not the idling is left for a predetermined time or longer. If it is left for a predetermined time or longer, the process proceeds to step S16, and the estimated temperature is increased by adding an offset value to the capacitor temperature Tc. The estimate moves to step S17. In this process, as shown in the horizontal axis time and vertical axis smoothing capacitor temperature graphs of FIG. 4, the time until the temperature gradually rises from the ambient temperature Tao and rises to the vicinity of the saturation temperature A is set as the idle standing time. It is used as a threshold value, and thereafter, an offset is added to the capacitor temperature Tc to estimate a higher capacitor temperature.

  Next, in step S17, it is determined whether the estimated capacitor temperature Tc is equal to or higher than the protection start temperature. If the temperature is equal to or higher than the protection start temperature, the process proceeds to step S18 and the protection process is executed. Here, what is characteristic is that, based on the temperature difference between the capacitor temperature Tc and the protection start temperature, (1) the discharge speed of the inverter pump 61 in FIG. The fan 12 for cooling the radiator of FIG. 1 is increased in rotational speed, (3) a combination of 1 and 2, (4) a reduction in the inverter output Pi, and the like are executed in combination.

  Steps S17 to S20 are repeated until the capacitor temperature Tc becomes equal to or lower than the protection start temperature in step S20. If it is determined in step S20 that the capacitor temperature Tc is equal to or lower than the protection start temperature, the process proceeds to the normal control in step S22 and returns to the first step S10.

As described above, by using the present embodiment, it is possible to realize control in which not only the temperature of the semiconductor switching element that is a heat generation source but also the temperature of the smoothing capacitor is equal to or lower than the allowable temperature. It is possible to prevent deterioration of the more smoothing capacitor such processing.

  In this embodiment, in order to easily incorporate into an existing hybrid vehicle, the capacitor temperature control is performed as an overheat prevention ECU different from the hybrid ECU and the motor ECU. However, the present invention is not limited to this. It may be realized by being incorporated in a motor ECU or the like.

It is a block diagram which shows the outline of a structure of the hybrid vehicle containing overheat protection ECU which concerns on embodiment of this invention. It is explanatory drawing explaining the structure of the inverter which concerns on embodiment of this invention. It is a flowchart figure which shows the flow of the capacitor | condenser temperature calculation process processed by thermal protection ECU which concerns on embodiment of this invention. It is explanatory drawing explaining the time change of the smoothing capacitor estimated temperature estimated with the heat protection ECU which concerns on embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Radiator for inverter, 11 Radiator for engine, 12 Fan, 13 Engine, 14 Planetary gear mechanism, 15 Wheel, 16 Differential gear, 21 Hybrid ECU, 22 Engine ECU, 23 Overheat protection ECU, 24 Motor ECU, 31 Motor generator, 32 Motor, 33, 34 Inverter, 35 Battery, 36 Semiconductor switching element, 37a Smoothing capacitor, 37b Snubber capacitor, 41, 42, 43 Temperature sensor, 51, 52, 53, 54, 55 Cooling water passage for inverter, 56, 57 Engine coolant passage, 61, 62 pump, 100 hybrid car.

Claims (4)

Hybrid vehicle drive device including an engine, an engine cooling system for cooling the engine, an inverter, an inverter cooling system for cooling the inverter, a switch element and a smoothing capacitor provided in the inverter, a motor generator, and a battery In
Inverter refrigerant temperature measuring means for measuring the refrigerant temperature of the inverter;
Engine refrigerant temperature measuring means for measuring the refrigerant temperature of the engine;
An inverter output measuring means for measuring the inverter output;
Low load time measuring means for measuring idling duration in a situation where the vehicle is stationary and the engine is idling to charge the battery;
Temperature estimating means for estimating the temperature of the smoothing capacitor based on an exponential function expression including an initial temperature value, a duration from the low load time measuring means, an inverter refrigerant temperature, an engine refrigerant temperature, and an inverter output;
If the estimated temperature obtained by the temperature estimation means exceeds the allowable temperature, execute one or more of an output reduction operation for reducing the inverter output and a cooling promotion operation for promoting cooling of the inverter cooling system to Overheating prevention means to prevent overheating;
A drive device for a hybrid vehicle comprising: In the hybrid vehicle drive device according to claim 1,
The temperature estimation means further includes:
Vehicle stopped vehicle state, and, when the time idling is continued becomes a predetermined time or more, the hybrid vehicle driving apparatus characterized by raising the estimated temperature by adding an offset value to the temperature of the smoothing capacitor. Hybrid vehicle drive device including an engine, an engine cooling system for cooling the engine, an inverter, an inverter cooling system for cooling the inverter, a switching element and a smoothing capacitor provided in the inverter, a motor generator, and a battery In the control method of
An inverter refrigerant temperature measuring step for measuring the inverter refrigerant temperature;
An engine refrigerant temperature measuring step for measuring the engine refrigerant temperature;
An inverter output measurement process for measuring the inverter output;
A low load time measuring step of measuring idling duration in a situation where the vehicle is stopped and the engine is idling to charge the battery;
A temperature estimation step of estimating the temperature of the smoothing capacitor based on an exponential function expression including an initial temperature value, a duration from the low load time measurement step, an inverter refrigerant temperature, an engine refrigerant temperature, and an inverter output;
If the estimated temperature obtained by the temperature estimation process exceeds the allowable temperature, execute one or more of an output reduction operation for reducing the inverter output and a cooling promotion operation for promoting cooling of the inverter cooling system to An overheating prevention process to prevent overheating;
A control method for a drive device for a hybrid vehicle, comprising: In the control method of the hybrid vehicle drive device according to claim 3,
The temperature estimation process further includes
Vehicle stopped vehicle state, and, when the time idling is continued is longer or equal to a predetermined time, the control of the hybrid vehicle drive device, characterized in that raising the estimated temperature by adding an offset value to the temperature of the smoothing capacitor Method.

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