JP2005117754A - Inverter device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To offer an inverter device which can grasp its power consumption at low cost. <P>SOLUTION: The inverter device drives a motor by converting DC voltage into pseudo AC voltage. It is equipped with a main circuit which receives primary DC voltage and outputs pseudo AC voltage to the secondary side, a secondary current detection means which detects the secondary current of this main circuit, and a control means which controls the main circuit from the secondary current detected by this secondary current detection means. This control means calculates the power consumption from the secondary current of the main circuit and the secondary current detected by the secondary current detection means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an inverter device suitable for driving, for example, an electric compressor used for in-vehicle air conditioning of an automobile.

  In recent years, the development of electric vehicles called HEV / PEV has been actively carried out in the field of automobiles due to the serious global environmental problems. In such an electric vehicle, in-vehicle air conditioning is performed using an electric compressor that uses a DC voltage of a battery (or a generator) of an automobile instead of an engine-driven compressor as in a conventional automobile. In that case, the inverter converts the DC voltage of the battery into a pseudo AC voltage and drives it by applying it to the motor of the electric compressor, and controls the rotational speed of the motor by controlling the PWM (pulse width modulation) duty, for example. It will be.

  By the way, in an electric vehicle, a driving spindle motor is driven using a battery as a power source. And, since the electric compressor for air conditioning in the vehicle is also driven by the battery, if the power consumption on the electric compressor side increases, there is a risk that driving of the spindle motor will be hindered due to excessive use of the battery, and running may become impossible .

Therefore, conventionally, a measure for calculating the power consumption of the electric compressor from the DC voltage on the primary side and the DC current on the primary side input from the battery to the inverter and limiting the rotational speed has been studied (for example, Patent Document 1). reference).
JP-A-6-72135

  Thus, in order to calculate the power consumption from the DC voltage and DC current on the primary side of the inverter, there is a problem that a detecting means such as a current transformer (current transformer) that detects the current value on the primary side of the inverter is required. was there. On the other hand, in a normal vector control inverter, a DC current on the secondary side of the inverter is detected to detect the position of the motor.

  The present invention has been made to solve the conventional technical problem, and provides an inverter device that can grasp power consumption at low cost.

  The inverter device of the present invention converts a DC voltage into a pseudo AC voltage and rotationally drives the motor, the DC circuit is input to the primary side, and the main circuit that outputs the pseudo AC voltage to the secondary side; A secondary side current detecting means for detecting the secondary side current of the main circuit; and a control means for controlling the main circuit based on the secondary side current detected by the secondary side current detecting means. Is characterized in that the power consumption is calculated based on the secondary side voltage of the main circuit and the secondary side current detected by the secondary side current detecting means.

  The inverter device of the invention of claim 2 is characterized in that, in the above, the control means limits the rotational speed of the motor when the calculated power consumption exceeds a predetermined value.

  In the inverter device according to a third aspect of the present invention, in the above inventions, the DC voltage is a voltage from a battery or a generator that is a power source of a driving spindle motor of an automobile, and the motor is an electric compressor for in-vehicle air conditioning of the automobile. It is a drive motor.

  According to the present invention, in the inverter device that rotates the motor by converting the DC voltage into the pseudo AC voltage, the power consumption is calculated based on the secondary side current and the secondary side voltage of the main circuit. The detection means for detecting the primary side current as in the prior art becomes unnecessary, and the cost can be reduced.

  When the driving motor of the electric compressor is driven to rotate by an inverter device using a DC voltage from a battery or a generator that is a power source of a driving spindle motor of an automobile, for example, the calculated power consumption is If the number of rotations of the motor for driving the electric compressor is limited in accordance with the rise, the main shaft motor can be driven without hindrance to ensure traveling.

Next, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic block diagram of an electric circuit of an electric vehicle according to an embodiment to which the present invention is applied. In this figure, reference numeral 1 denotes an electric vehicle battery (high voltage system: DC 300 V), and the battery 1 is charged by a generator (not shown). The DC voltage of the battery 1 is input to the main spindle inverter 2 of the electric vehicle. This spindle inverter 2 is composed of six switching elements and the like, and converts the DC voltage of the battery 1 into a three-phase pseudo AC voltage in the form of a variable voltage rectangular pulse train. The pseudo AC output from the spindle inverter 2 The voltage is applied to the driving spindle motor 3 so that the electric vehicle runs.

  Reference numeral 4 denotes an air conditioner inverter as an inverter device of the present invention which constitutes a car air conditioner of an electric vehicle. This air conditioner inverter 4 is composed of a controller 11 as a control means composed of a general-purpose microcomputer, a main circuit 12 composed of six switching elements, and the like. By controlling the ON / OFF timing of the element, the DC voltage of the battery 1 input to the primary side of the main circuit 12 is converted into a three-phase pseudo AC voltage in the form of a rectangular pulse train of variable voltage and output to the secondary side. . Then, the three-phase pseudo AC voltage output from the main circuit 12 is applied to the motor 6 for driving the electric compressor to drive the electric compressor. This electric compressor is a refrigerant compressor constituting a refrigerant circuit of a car air conditioner.

  FIG. 2 shows waveforms of the secondary side voltage and the secondary side current of the main circuit 12. The controller 11 of the air conditioner inverter 4 detects the rotor position of the motor 6 by a so-called vector control method and determines the ON-OFF timing of each switching element of the main circuit 12. For this purpose, the secondary side current of the main circuit 12 is determined. Current transformers 13 and 14 (secondary side current detection means) are provided, and the outputs of the current transformers 13 and 14 are input to the controller 11. In the case of the embodiment, the primary voltage is also input to the controller 11 in order to detect a voltage abnormality of the battery 1.

  The operation of the air conditioner inverter 4 will be described with the above configuration. The controller 11 of the air conditioner inverter 4 receives the required rotation speed (air conditioner) of the motor 6 determined from the control panel in the vehicle based on the air conditioning conditions such as the set temperature in the vehicle, the blowout temperature (the temperature of the blown air), the inboard temperature, and the amount of solar radiation The number of rotations (frequency) of the compressor driving motor 6 calculated from the conditions is input. The controller 11 is based on the required rotational speed, and in addition to this, the set rotational speed of the motor 6 in consideration of the limiting operation condition for protecting the overcurrent of the motor 6 and the discharge refrigerant temperature and the rotational speed change speed condition of the motor 6. Based on this set rotational speed and the actual rotational speed of the motor 6, each switching element of the main circuit 12 is driven by the PID method, for example.

  The actual rotational speed control is performed by a so-called PWM (pulse width modulation) method. As a result, the in-vehicle temperature is maintained at the set temperature.

  Further, the controller 11 uses the secondary side current of the main circuit 12 input from the current transformer 13 or 14 and the secondary side voltage of the main circuit 12 which is originally grasped, and executes the calculation of the following formula 1 to execute the air conditioner. The power consumption of the motor 6 including the inverter 4 is calculated.

  Here, the DC voltage in Equation 1 is the secondary voltage of the main circuit 12, and the peak value of the current is the peak value of the secondary current of the main circuit 12, which is multiplied by the respective effective value, and three Multiply by the coefficient for the phase. The electric power is the power consumption of the motor 6 including the air conditioner inverter 4. In the case of vector control, the secondary output is ideally a sine wave, but in actuality it may deviate from the sine wave, so a predetermined correction coefficient is multiplied.

  When the calculated power consumption exceeds a predetermined value, the controller 11 prohibits an increase in the rotational speed of the motor 6 or performs a limiting operation to decrease the rotational speed regardless of a request from the control panel in the vehicle. Execute. This avoids the disadvantage that the spindle motor 3 cannot be driven due to excessive use of the DC voltage of the battery 1.

  In this case, since the controller 11 calculates power consumption using the secondary side voltage and the secondary side current of the main circuit 12, a current transformer is provided on the primary side of the main circuit 12 for power calculation as in the prior art. This eliminates the need to reduce the part cost.

  In the embodiment, the inverter device of the present invention is applied to a motor for driving an electric compressor of a car air conditioner. However, the present invention is not limited to this, and the present invention is effective for various devices that drive a motor with an inverter.

It is a schematic block diagram of the electric circuit of the electric vehicle to which this invention is applied. It is a wave form diagram of the secondary side voltage and secondary side current of the air-conditioner inverter (inverter device) of Drawing 1.

Explanation of symbols

1 Battery 2 Spindle Inverter 3 Spindle Motor 4 Air Conditioner Inverter (Inverter Device)
6 Motor for driving compressor 11 Controller (control means)
12 Main circuit 13, 14 Current transformer (secondary side current detection means)

Claims (3)

In an inverter device that rotates a motor by converting a DC voltage into a pseudo AC voltage,
A main circuit that receives the DC voltage on the primary side and outputs the pseudo AC voltage on the secondary side;
Secondary-side current detection means for detecting the secondary-side current of the main circuit;
Control means for controlling the main circuit based on the secondary current detected by the secondary current detection means,
The control device calculates power consumption based on a secondary side voltage of the main circuit and the secondary side current detected by the secondary side current detection unit.   2. The inverter device according to claim 1, wherein the control means limits the number of rotations of the motor when the calculated power consumption exceeds a predetermined value. The DC voltage is a voltage from a battery or a generator that is a power source of a driving spindle motor of an automobile,
The inverter device according to claim 1, wherein the motor is a driving motor for an electric compressor for air conditioning in a vehicle.

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