JP2013242110A - Warming-up controller of inverter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a warming-up controller of an inverter which can warm up in a short time under a low temperature environment as well, and also can uniformize generation of heat of each switching element of an inverter circuit.SOLUTION: A controller 40 flows a DC current at an electrical angle at which the maximum current flows in a winding of each phase of an electric motor 60 based on a three-phase AC current waveform to be supplied to the winding of each phase of the electric motor 60 when the electric motor 60 is driven to rotate in a state in which a warming-up mode of flowing-out of a current from an aluminum electrolytic capacitor 80 is set when a temperature of the aluminum electrolytic capacitor 80 detected by a temperature sensor 90 is lower than a specified temperature, and also controls switching elements S1 to S6 of an inverter circuit 20 so as to sequentially switch the winding through which the maximum current flows.

Description

  The present invention relates to an inverter warm-up control device.

  An air conditioner disclosed in Patent Literature 1 includes a DC power source, a DC converter, an inverter device that outputs an AC current to drive an electric motor, and a compressor that is driven by the electric motor. The inverter device includes a switching element. Is used to energize the stepped-down DC voltage from the DC converter so that a DC current flows through the winding of the motor, and heat the compressor by heating the winding.

JP 2005-326054 A

  By the way, in an environment of extremely low temperature (−20 ° C. or lower), the ESR (= equivalent series resistance) of a smoothing capacitor (such as an aluminum electrolytic capacitor) connected to the inverter circuit increases rapidly, and switching in the switching element of the inverter circuit is performed. The surge voltage at the time increases.

  For this reason, at low temperatures, first, warm-up control is performed in which current is supplied to the circuit to warm each element such as a capacitor. However, this warm-up control is performed in a short time and the heat generation of each switching element in the inverter circuit is also equalized. .

  An object of the present invention is to provide an inverter warm-up control device that can warm up in a short time even in a low-temperature environment and can equalize the heat generation of each switching element of the inverter circuit.

  According to the first aspect of the present invention, the inverter circuit includes a plurality of switching elements bridge-connected, and a DC power source and a capacitor connected in parallel are connected to the input side of the inverter circuit, and the output side of the inverter circuit In addition, there is provided a warm-up control device for an inverter to which a winding of each phase of the motor is connected, the temperature detecting means for detecting the temperature of the capacitor, and the temperature of the capacitor detected by the temperature detecting means is a specified temperature. The electric motor based on a three-phase alternating current waveform supplied to the winding of each phase of the electric motor when the electric motor is rotationally driven in a warm-up mode in which current is taken from the capacitor at a lower temperature The DC current is applied at an electrical angle at which the maximum current flows through the windings of each phase of the coil, and the windings through which the maximum current flows are sequentially switched. And control means for controlling the switching elements of the inverter circuit, further comprising a a gist.

  According to the first aspect of the present invention, the temperature of the capacitor is detected by the temperature detecting means. Then, when the temperature of the capacitor detected by the temperature detecting means is lower than the specified temperature, the control means is in a warm-up mode in which current is taken from the capacitor, and when rotating the motor, each phase of the motor Based on the three-phase alternating current waveform supplied to the windings, the inverter circuit is switched so that a direct current flows at an electrical angle at which the maximum current flows through the windings of each phase of the motor and the windings that pass the maximum current are sequentially switched. The element is controlled.

  Therefore, warm-up can be performed in a short time even in a low-temperature environment by flowing the maximum current, and heat generation of each switching element of the inverter circuit can be equalized by sequentially switching the windings to flow.

  According to a second aspect of the present invention, in the warm-up control device for an inverter according to the first aspect, when the control means switches the winding through which the maximum current flows, no current flows through all the windings. A period should be provided.

  According to a third aspect of the present invention, in the warm-up control apparatus for an inverter according to the first or second aspect, the control means may change the current gradually when switching the winding through which the maximum current flows. .

  According to the present invention, warm-up can be performed in a short time even in a low temperature environment, and the heat generation of each switching element of the inverter circuit can be equalized.

The circuit diagram of the warm-up control apparatus of the inverter in embodiment. The wave form diagram which shows U-phase current, W-phase current, and V-phase current. FIG. 3 is a waveform diagram showing a U-phase current in the waveform diagram of FIG. 2. The characteristic view which shows the relationship between temperature and ESR. The time chart which shows the fluctuation | variation of a voltage. The characteristic view which shows the relationship between temperature and element breakdown voltage (drain-source voltage). The wave form diagram which shows the U-phase electric current, W-phase electric current, and V-phase electric current of another example. FIG. 8 is a waveform diagram showing a U-phase current in the waveform diagram of FIG. 7.

Hereinafter, an embodiment in which the present invention is embodied in a vehicle that is also used in a refrigerated warehouse will be described with reference to the drawings. The vehicle temperature specification is about −40 ° C. to + 80 ° C.
As shown in FIG. 1, the inverter (three-phase inverter) 10 includes an inverter circuit 20 and a drive circuit 30. A battery 50 as a DC power source is connected to the input side of the inverter circuit 20 and a compressor driving motor 60 is connected to the output side. A three-phase AC motor is used for the electric motor 60. The electric motor 60 has windings 61, 62, 63, and the windings 61, 62, 63 of each phase of the electric motor 60 are connected to the output side of the inverter circuit 20.

  The inverter circuit 20 is provided with six switching elements S1 to S6. A power MOSFET is used for each of the switching elements S1 to S6. Thus, the inverter circuit 20 includes a plurality of switching elements S1 to S6 that are bridge-connected. An IGBT (insulated gate bipolar transistor) may be used as the switching element. Feedback diodes D1 to D6 are connected in reverse parallel to the switching elements S1 to S6, respectively.

  In the inverter circuit 20, the first and second switching elements S1 and S2, the third and fourth switching elements S3 and S4, and the fifth and sixth switching elements S5 and S6 are connected in series, respectively. The first, third, and fifth switching elements S1, S3, and S5 are connected to the positive terminal side of the battery 50 as a DC power source, and the second, fourth, and sixth switching elements S2, S4, and S6 are connected. Is connected to the negative terminal side of the battery 50.

  The connection point between the switching elements S1, S2 constituting the upper and lower arms for the U phase is at the U phase terminal of the electric motor 60, and the connection point between the switching elements S3, S4 constituting the upper and lower arms for the V phase is Connection points between the switching elements S5 and S6 constituting the upper and lower arms for the W phase are connected to the V phase terminal of the electric motor 60 and the W phase terminal of the electric motor 60, respectively.

The rated voltage of the battery 50 is 48 volts, for example, and the withstand voltages of the switching elements S1 to S6 are about 75 volts.
Current sensors 70 and 71 are provided between the inverter circuit 20 and the electric motor 60. Current sensors 70 and 71 detect current values of currents Iu and Iw of two phases (U-phase and W-phase in this embodiment) of three-phase currents Iu, Iv, and Iw supplied to electric motor 60.

  On the input side of the inverter circuit 20, an aluminum electrolytic capacitor 80 is connected in parallel with the battery 50. The first, third and fifth switching elements S1, S3 and S5 are connected to the positive terminal side of the aluminum electrolytic capacitor 80, and the second, fourth and sixth switching elements S2, S4 and S6 are connected to the aluminum electrolytic capacitor 80. Is connected to the negative terminal side. In FIG. 1, an aluminum electrolytic capacitor 80 can be considered as an equivalent capacitor in which an ideal capacitor C and a resistance component R are connected in series. The resistance component R is an equivalent series resistance (ESR).

Thus, the battery 50 and the aluminum electrolytic capacitor 80 as DC power sources connected in parallel are connected to the input side of the inverter circuit 20.
The controller 40 constituting the inverter warm-up control device detects the voltage Vb of the inverter circuit 20. The voltage Vb has a function of detecting the overvoltage (surge voltage) generated by the ESR of the aluminum electrolytic capacitor 80 and protecting the switching elements S1 to S6. That is, if the voltage Vb becomes excessively high, the switching elements S1 to S6 may break down. Therefore, if the voltage applied to the switching elements S1 to S6 becomes larger than the set value due to a surge voltage or the like, the inverter circuit 20 The drive is stopped.

Further, a temperature sensor 90 for detecting the temperature of the aluminum electrolytic capacitor 80 is provided, and the temperature sensor 90 as temperature detecting means is connected to the controller 40.
The controller 40 is mainly composed of a microcomputer. The controller 40 includes a memory 41. The memory 41 stores various control programs necessary for driving the electric motor 60 and various data and maps necessary for the execution thereof. The control program includes a control program for rotationally driving a normal electric motor (motor) 60, a control program for causing a direct current to flow through the electric motor 60 for warm-up at a low temperature, and the like.

  The controller 40 is connected to the gates of the switching elements S1 to S6 via the drive circuit 30. Current sensors 70 and 71 are connected to the controller 40. And the controller 40 outputs the control signal which controls the electric motor 60 so that it may become target output based on the detection signal of each sensor 70 and 71 to each switching element S1-S6 via the drive circuit 30. FIG. The inverter circuit 20 converts the DC voltage supplied from the battery 50 and the aluminum electrolytic capacitor 80 into a three-phase AC voltage having an appropriate frequency and outputs it to the electric motor 60.

In the present embodiment, the inverter warm-up control device includes a controller 40 and a temperature sensor 90.
Next, the operation of the inverter 10 (warm-up control device) will be described.

  In FIG. 2, on the upper side, waveforms of the U-phase current Iu, the W-phase current Iw, and the V-phase current Iv at a normal time that is not low temperature are shown. Further, in FIG. 2, the lower side shows waveforms of the U-phase current Iu, the W-phase current Iw, and the V-phase current Iv at low temperatures (warming up).

  When the temperature of the aluminum electrolytic capacitor 80 detected by the temperature sensor 90 is higher than a specified temperature (for example, −20 ° C.), the controller 40 turns on the switching elements S1, S4, and S6 at the same time and sets the U-phase current Iu. Shed. Further, the switching elements S3, S2, and S6 are simultaneously turned on to pass the V-phase current Iv. Further, switching elements S5, S2, and S4 are simultaneously turned on to pass W-phase current Iw. In this way, as an operation of the inverter 10, a DC voltage is input from the battery 50 (aluminum electrolytic capacitor 80), and the switching elements S1 to S6 connected in a bridge are turned on / off, and output in accordance with the on / off operation. The electric motor 60 on the side is energized. At this time, the controller 40 is adjusted so that a desired maximum current flows in each phase.

  Moreover, the regenerative electric power which generate | occur | produces with electricity supply of the electric motor 60 is returned to the power supply side. That is, regenerative power (regenerative current) from the electric motor 60 is accumulated in the aluminum electrolytic capacitor 80 via the feedback diodes D1 to D6. This regenerative energy is used during powering.

  The solid line on the upper side of FIG. 3 shows the waveform of the normal U-phase current Iu that is not low temperature, and the solid line on the lower side of FIG. 3 shows the waveform of the U-phase current Iu at the low temperature (warming up). Show. 3 shows the waveforms of the W-phase current Iw and the V-phase current Iv at a normal time that is not low temperature, with broken lines on the upper side of FIG. 3, and the W-phase at low temperature (warming up) with the broken lines on the lower side of FIG. The waveforms of current Iw and V-phase current Iv are shown.

  When the temperature of the aluminum electrolytic capacitor 80 detected by the temperature sensor 90 is higher than a specified temperature (for example, −20 ° C.), the controller 40, as shown on the upper side in FIGS. The switching elements S1 to S6 of the inverter circuit 20 are turned on / off so that sinusoidal current flows as the phase current Iw and the V-phase current Iv.

  On the other hand, the controller 40 as the control means performs a warm-up mode in which current is taken from the aluminum electrolytic capacitor 80 when the temperature of the aluminum electrolytic capacitor 80 detected by the temperature sensor 90 is lower than a specified temperature (for example, −20 ° C.). Set. In this warm-up mode, the maximum current Imax is sequentially applied to the windings of each phase of the motor 60 based on the current waveform of the three-phase alternating current supplied to the windings of each phase of the motor 60 when the motor 60 is rotationally driven. Control so that a DC warm-up current flows. Specifically, during normal operation in which the electric motor 60 is rotationally driven, the switching elements S1 to S6 of the inverter circuit 20 are controlled so that the maximum current Imax is supplied to the windings of each phase at the electrical angles θ1, θ2, and θ3. In the warm-up mode, the switching elements S1 to S1 of the inverter circuit 20 are arranged so that the DC warm-up current of the maximum current Imax is sequentially supplied to the windings of the respective phases at the same electrical angles θ1, θ2, and θ3 as in the normal operation. S6 is controlled.

  Referring to FIG. 3, when attention is paid to the U-phase current Iu, the maximum current Imax is obtained at the electrical angle θ1 during normal operation, and the W-phase current Iw and the V-phase current Iv are respectively current I2 at the electrical angle θ1. In the warm-up mode, the direct current of the maximum current Imax is supplied to the U-phase winding from the timing t1 when the electrical angle θ1 is reached, and the direct current of the current I2 is supplied at the timing when the maximum current Imax is supplied to the other phases. The switching elements S1 to S6 of the inverter circuit 20 are controlled so that a current is supplied.

  Similarly, when focusing on the W-phase current Iw, the maximum current Imax is obtained at the electrical angle θ2 during normal operation, and the U-phase current Iu and the V-phase current Iv are respectively current I2 at the electrical angle θ2. In the warm-up mode, the direct current of the maximum current Imax is supplied to the W-phase winding from the timing t2 when the electrical angle θ2 is reached, and the direct current of the current I2 is supplied at the timing when the maximum current Imax is supplied to the other phases. The switching elements S1 to S6 of the inverter circuit 20 are controlled so that a current is supplied.

  Similarly, when focusing on the V-phase current Iv, during the normal operation, the maximum current Imax is obtained at the electrical angle θ3, and the U-phase current Iu and the W-phase current Iw are each the current I2 at the electrical angle θ3. In the warm-up mode, the direct current of the maximum current Imax is supplied to the V-phase winding from the timing t3 when the electrical angle θ3 is reached, and the direct current of the current I2 is supplied at the timing when the maximum current Imax is supplied to the other phases. The switching elements S1 to S6 of the inverter circuit 20 are controlled so that a current is supplied.

  In this way, as shown in FIG. 2, during the warm-up, the windings in which the direct current flows at the electrical angles θ1, θ2, and θ3 in which the maximum current flows through the windings of the respective phases of the electric motor 60 and the windings in which the maximum current Imax flows are sequentially switched.

  At low temperatures, the warm-up current (U-phase current Iu, W-phase current Iw, V-phase current Iv) supplied to each phase of the electric motor 60 in the warm-up mode is gradually increased until the current value reaches the maximum current Imax. The switching elements S1 to S6 of the inverter circuit 20 are controlled so that the current value becomes large. That is, the current is gradually changed (gradual change).

  In addition, when switching the phase that supplies the DC warm-up current of the maximum current Imax in the warm-up mode at low temperatures, the current value gradually decreases with respect to the phase that has been supplied with the maximum current Imax. The switching elements S1 to S6 of the inverter circuit 20 are controlled. That is, the current is gradually changed (gradual change).

  The switching elements S1 to S6 are heated by energization of the switching elements S1 to S6. However, since the phase in which the direct current flows is sequentially controlled at the same timing, not only the specific switching elements but also all the switching elements. S1 to S6 are heated uniformly. At this time, since a direct current is supplied to the winding, the electric motor 60 does not rotate and no abnormal noise is generated.

  Further, in the warm-up mode in which the warm-up current is supplied to the electric motor 60, the regeneration to the battery 50 is not performed, and the mode is limited to the mode in which the current is taken from the aluminum electrolytic capacitor 80. Further, regarding the ripple voltage generated when the three-phase alternating current is supplied to the electric motor during the normal operation, the ripple voltage can be reduced by supplying the direct current in the warm-up mode. Thereby, the current supplied to the electric motor can be increased within the allowable current of the switching elements S1 to S6 in the warm-up mode.

  In addition, since the phase through which the direct current of the maximum current Imax flows is sequentially switched, the switching elements S1 to S6 can be uniformly heated as compared with the method of supplying the direct current of the maximum current Imax only to a certain phase. In particular, when the inverter circuit becomes large, it is possible to prevent the temperature distribution in the inverter circuit from becoming uneven.

  Further, in the warm-up mode, current is taken out from the aluminum electrolytic capacitor 80, so that the temperature rises and the ESR becomes small. By reducing the ESR (equivalent series resistance; internal resistance) of the aluminum electrolytic capacitor 80, generation of an overvoltage due to a surge voltage is suppressed.

  The warm-up current has a map corresponding to the battery voltage, and if the voltage is low, the warm-up current is increased (the battery voltage is detected and the warm-up current is made variable). That is, since the sum of the battery voltage and the voltage increase (ΔV) due to ESR does not exceed the element breakdown voltage, the current for warming up is increased when the battery voltage is low.

  FIG. 4 shows the relationship between the temperature and the value of the equivalent series resistance (ESR) of the aluminum electrolytic capacitor 80. When the temperature becomes lower than −20 ° C., for example, the value of the equivalent series resistance (ESR) of the aluminum electrolytic capacitor 80 increases rapidly. When current is supplied to the motor by inverter control in such a low temperature state, a large surge voltage is generated due to a large ESR (equivalent series resistance; internal resistance) of the electrolytic capacitor when power regeneration occurs. In this embodiment, when the environmental temperature is extremely low (−40 ° C. or the like), first, control is performed so that a direct current is supplied to the motor in the warm-up mode. It is possible to drive the electric motor after reducing the value.

  FIG. 5 is an explanatory diagram of the breakdown voltage of the switching element during normal operation. In order to prevent the switching element from being destroyed during the use of the inverter circuit, it is necessary that the sum of the surge voltage ΔV generated by switching of the switching element and the battery voltage does not exceed the element withstand voltage. In this embodiment, the surge voltage ΔV generated by ESR can be reduced by raising the temperature of the aluminum electrolytic capacitor 80 by warming up.

  FIG. 6 shows the relationship between the breakdown voltage of the drain-source voltage of the switching element and the temperature. The breakdown voltage decreases with temperature. That is, when the temperature is lowered, the withstand voltage of the drain-source voltage of the switching element is lowered. In the present embodiment, the switching elements S1 to S6 can be heated by warming up to increase the breakdown voltage (strong against ripples).

  As described above, even when the environmental temperature is extremely low (−40 ° C. or the like), the warm-up current can be increased without stopping the inverter 10 by detecting the overvoltage, and the warm-up can be performed in a short time. Therefore, in the vehicle used in the refrigerated warehouse, it is possible to shorten the waiting time until the normal operation becomes possible after the key-on.

According to the above embodiment, the following effects can be obtained.
(1) As a configuration of the inverter warm-up control device, a temperature sensor 90 and a controller 40 are provided. When the temperature of the aluminum electrolytic capacitor 80 detected by the temperature sensor 90 is lower than a specified temperature, the controller 40 is as follows. To do. Each phase of the electric motor 60 is based on the three-phase alternating current waveform supplied to the windings of the respective phases of the electric motor 60 when the electric motor 60 is rotationally driven in the state where the warm-up mode for taking out current from the aluminum electrolytic capacitor 80 is set The switching elements S1 to S6 of the inverter circuit 20 are controlled so that a direct current flows at the electrical angles θ1, θ2, and θ3 through which the maximum current Imax flows, and the windings through which the maximum current Imax flows are sequentially switched.

  As a result, the aluminum electrolytic capacitor 80 can be warmed up in a short time even in a low temperature environment by flowing a DC maximum current. Further, by sequentially switching the windings to be passed, the temperature can be efficiently raised and the heat generation of each switching element S1 to S6 of the inverter circuit 20 can be equalized.

(2) When switching the winding through which the maximum current flows, the controller 40 gradually changes (gradually changes) the current. Thereby, it becomes difficult to receive the influence of a residual magnetic flux.
The embodiment is not limited to the above, and may be embodied as follows, for example.

  As shown in FIGS. 7 and 8, when switching the winding through which the maximum current flows, a pause period T1 in which no current flows through all the windings may be provided. By providing the pause period T1, it is possible to make it less susceptible to adverse effects due to remaining residue when continuously flowing.

  Also in this case, it is preferable to gradually change the current when switching the winding through which the maximum current flows. By gradually changing (gradually changing) the current at the time of switching, it becomes difficult to be affected by the residual magnetic flux.

・ Electric motor is not limited.
・ When passing current through one phase during warm-up at low temperature, one upper arm and two lower arms of the three upper arms and three lower arms were turned on, but one upper arm and one lower arm The arm may be turned on.

  DESCRIPTION OF SYMBOLS 10 ... Inverter, 20 ... Inverter circuit, 40 ... Controller, 50 ... Battery, 60 ... Electric motor, 80 ... Aluminum electrolytic capacitor, 90 ... Temperature sensor, S1 ... Switching element, S2 ... Switching element, S3 ... Switching element, S4 ... Switching Element, S5 ... switching element, S6 ... switching element.

Claims (3)

A plurality of switching elements bridged in the inverter circuit, a DC power source and a capacitor connected in parallel are connected to the input side of the inverter circuit, and windings of each phase of the motor are connected to the output side of the inverter circuit Is a warm-up control device for an inverter connected to
Temperature detecting means for detecting the temperature of the capacitor;
When the temperature of the capacitor detected by the temperature detecting means is lower than a specified temperature, the winding of each phase of the motor is performed when the motor is rotated in a warm-up mode in which current is taken from the capacitor. Based on the three-phase AC current waveform supplied to the wire, the inverter circuit is configured so that a DC current flows at an electrical angle at which the maximum current flows through the windings of each phase of the motor and the windings through which the maximum current flows are sequentially switched. Control means for controlling the switching element;
An inverter warm-up control device characterized by comprising:   2. The inverter warm-up control device according to claim 1, wherein when the winding for passing the maximum current is switched, the control means provides a pause period during which no current flows in all the windings.   The inverter warm-up control device according to claim 1 or 2, wherein the control means gradually changes the current when switching the winding through which the maximum current flows.