JP2016082545A - Electric circuit, motor compressor and control method of electric circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric circuit reconciling high speed discharge of a capacitor and compaction of a circuit board, and to provide a motor compressor and a control method of an electric circuit.SOLUTION: An electric circuit 1 includes a capacitor 40 connected with a battery 30, first wiring having a first resistor 60 installed in parallel with the capacitor 40, and second wiring having a second resistor 70 of lower resistance than the first resistor 60 installed in parallel with the capacitor 40. When a voltage is applied to the capacitor 40 by the battery 30, discharge current of the capacitor 40 flows through the first wiring, and when the voltage applied to the capacitor 40 by the battery 30 is interrupted, discharge current of the capacitor 40 flows through the second wiring.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electric circuit, an electric compressor, and an electric circuit control method, and more specifically, to an electric circuit, an electric compressor, and an electric circuit control method for reducing the discharge time of a capacitor.

A capacitor connected to a power source in an electric circuit accumulates electric energy when a voltage is input from the power source, and smoothes fluctuations in current and voltage. When a capacitor has a large capacity, when an unforeseen situation occurs, such as disconnection of the power supply, disconnection of the high-voltage cable connected to the power supply, or removal of the high-voltage connector, for example, electric shock to the human body or short-circuit accident It is necessary to discharge the electrical energy stored in the capacitor in order to prevent the occurrence of this. However, since recent capacitors have a very high insulation resistance, the stored electric energy is hardly discharged by itself.
On the other hand, for example, Patent Document 1 discloses discharging by connecting a resistor in parallel with a capacitor.

Japanese Patent No. 3678165

Regarding the discharge of capacitors, in order to prevent the occurrence of electric shocks and short circuit accidents to the human body as described above, it is required to increase the discharge time. About discharge time (tau), it calculates | requires by the following formula | equation (1).
τ = C × R (1)
In the equation (1), τ is the discharge time (discharge time constant), C is the capacity of the capacitor, and R is the resistance value of the capacitor discharging resistor. That is, in order to increase the discharge time for a certain capacitor, it is necessary to reduce the resistance value of the resistor, but in this case, the power capacity of the resistor is increased. When the power capacity of the resistor is large, the resistor becomes large, which leads to an increase in the size of the circuit board. In general, it is required to suppress the area of the circuit board.
However, in the invention disclosed in Patent Document 1, the resistance value of the capacitor discharging resistor is not examined, and the circuit board is not considered to be downsized.

  The present invention has been made in view of such circumstances, and provides an electric circuit, an electric compressor, and a control method for an electric circuit that can achieve both high-speed discharge time of a capacitor and miniaturization of a circuit board. For the purpose.

In order to solve the above problems, the electric circuit, the electric compressor, and the control method of the electric circuit of the present invention employ the following means.
A capacitor connected to the battery, a first wiring having a first resistor placed in parallel with the capacitor, and a second resistor having a resistance value lower than that of the first resistor placed in parallel with the capacitor. And when the voltage is applied to the capacitor by the battery, the discharge current of the capacitor flows through the first wiring, and the voltage to the capacitor by the battery is cut off. Adopts an electric circuit in which the discharge current of the capacitor flows through the second wiring.

  According to the present invention, when a voltage is applied to the capacitor by the battery, the discharge current of the capacitor flows through the first wiring, and when the voltage to the capacitor is cut off, the discharge current of the capacitor passes through the second wiring. Therefore, when discharging the electric energy stored in the capacitor, it is possible to perform discharge for an appropriate discharge time according to ON / OFF of the battery. In particular, when the voltage from the battery is interrupted due to unforeseen circumstances such as disconnection of the battery, disconnection of the high-voltage cable connected to the battery, or removal of the high-voltage connector, the second resistance having a lower resistance value Since the discharge is performed, the discharge time is shorter than when the first wiring is selected, so that the occurrence of a short circuit accident or the like can be prevented.

  In the above invention, a switch for switching selection of the first wiring and the second wiring is provided, and when the switch is ON, the discharge current of the capacitor flows through the second wiring, and when the switch is OFF, the capacitor The discharge current may flow through the first wiring.

  According to the present invention, the switch for switching between the first wiring and the second wiring is provided, and the discharge current flows through the second wiring when the switch is ON, and flows through the first wiring when the switch is OFF. The wiring can be switched by a simple method of turning on / off the switch according to the presence or absence of voltage application.

  In the above invention, a control unit may be provided that outputs a signal for controlling ON / OFF of the switch in accordance with whether or not voltage is applied from the battery to the capacitor.

  According to the present invention, the switch is turned ON / OFF by the signal output from the control unit, that is, the first wiring and the second wiring are switched, so that the battery is disconnected and the high voltage cable connected to the battery is disconnected. When the input of voltage is interrupted by removing the high voltage connector, etc., the control unit outputs a signal corresponding to it, and switching to the second wiring is performed, so that the discharging is performed more than when the first wiring is selected. A resistor with a short time can be selected.

  In the above invention, the switch may be turned on when the control unit is inoperative.

  According to the present invention, when the control unit is not operated, the switch is turned on, and therefore the control unit is not operated due to an unexpected situation such as the power supply being cut off. Even if the voltage input from the battery is cut off, the second wiring is selected because the switch is ON, and the discharge time is shorter than when the first wiring is selected due to the resistance having a low resistance value. Discharge can be performed. That is, even if the control by the control unit cannot be performed, the capacitor can be automatically and safely discharged at high speed when the voltage input from the battery is interrupted.

  The present invention employs an electric compressor including any of the electric circuits described above.

  According to the present invention, since the electric compressor includes any one of the electric circuits described above, when discharging the electric energy stored in the capacitor of the electric compressor, the electric compressor is appropriately adapted to ON / OFF of the battery. It is possible to discharge for a long discharge time. In particular, when the voltage from the battery is interrupted due to an unexpected situation such as disconnection of the battery, disconnection of the high-voltage cable connected to the battery, or removal of the high-voltage connector, the discharge is caused by the resistance having a lower resistance value. Since the discharge time is shortened, the occurrence of a short-circuit accident or the like can be prevented.

  The present invention provides a capacitor connected to a battery, a first wiring having a first resistor installed in parallel with the capacitor, and a resistance value lower than that of the first resistor installed in parallel with the capacitor. A second wiring having a second resistance, and when a voltage is applied to the capacitor by the battery, passing a discharge current of the capacitor to the first wiring; and When the voltage is cut off, a method for controlling the electric circuit is provided, comprising: passing a discharge current of the capacitor to the second wiring.

  According to the present invention, when a voltage is applied to the capacitor by the battery, the discharge current of the capacitor is passed to the first wiring, and when the voltage to the capacitor is cut off, the discharge current of the capacitor is supplied to the second wiring. Therefore, when discharging the electric energy stored in the capacitor, it is possible to perform discharge for an appropriate discharge time according to ON / OFF of the battery. In particular, when the voltage from the battery is interrupted due to an unexpected situation such as disconnection of the battery, disconnection of the high-voltage cable connected to the battery, or removal of the high-voltage connector, the discharge is caused by the resistance having a lower resistance value. Since the discharge time is shorter than when the first wiring is selected, the occurrence of a short-circuit accident or the like can be prevented.

  According to the present invention, it is possible to discharge a capacitor at high speed without increasing the circuit area by providing a discharging resistor having a low resistance value in addition to a normal discharging resistor.

1 is a schematic configuration diagram illustrating an electric circuit according to an embodiment of the present invention. It is a schematic structure figure showing a part of electric circuit concerning one embodiment of the present invention. It is the chart which showed the case classification of the control processing of the control part of the electric circuit concerning one embodiment of the present invention. It is the schematic block diagram which showed the conventional electric circuit as a reference example of this invention.

Hereinafter, an embodiment of an electric circuit, an electric compressor, and an electric circuit control method according to the present invention will be described with reference to the drawings.
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows a schematic configuration of an electric circuit according to the present embodiment.
As shown in FIG. 1, the electric circuit 1 includes a motor 10, an inverter 20, a battery 30, a capacitor 40, an input terminal 50, a first resistor 60, a second resistor 70, and a switch 80 as main components. The first resistor 60 is installed in parallel with the capacitor 40 and is provided on the first wiring. The second resistor 70 is installed in parallel with the capacitor 40 and is provided on the second wiring. In the present embodiment, it is assumed that the resistance value of the second resistor 70 is lower than the resistance value of the first resistor 60.
The electric circuit 1 is assumed to be a circuit provided in an electric compressor (not shown).
When the electric compressor is mounted on the vehicle, a single-phase DC high voltage (for example, 150 to 450 (V)) is input to the inverter 20 from the battery 30 mounted on the vehicle, and PWM control (Pulse Width Modulation) is performed. : Converted to three-phase alternating current by pulse width modulation control) and output to the motor 10, and the motor 10 and the compressor (not shown) are rotated at a desired rotational speed.
The capacitor 40 is connected to the high voltage input side of the inverter 20 and smoothes fluctuations in current and voltage at the input portion of the inverter 20 due to PWM control. When a high voltage is applied to the capacitor 40, the electrical energy stored in the capacitor 40 is expressed by the following equation (2).
J = C / 2 × V ² (2)
In the equation (2), J is electrical energy stored in the capacitor 40, C is the capacity of the capacitor 40, and V is the voltage of the battery 30.

In the electric compressor mounted on the vehicle, the battery 30 is disconnected, the high voltage cable connected to the battery 30 is disconnected, the high voltage connector is removed, etc., and the human body caused by the electric energy stored in the capacitor 40 is removed. In order to prevent an electric shock or a short-circuit accident, it is necessary to discharge the electric energy stored in the capacitor 40 when a high voltage is no longer applied to the inverter 20 for the reasons described above.
In the present embodiment, the first resistor 60 and the second resistor 70 are connected in parallel with the capacitor 40 and are switched by the switch 80, and the electrical energy stored in the capacitor 40 is discharged by one of the resistors. And The ON / OFF control of the switch 80 is performed by outputting a signal from the microcomputer (control unit) 100 according to whether or not voltage is applied from the battery 30 to the capacitor 40.

FIG. 2 shows a schematic configuration of a part of the electric circuit according to the present embodiment.
The microcomputer 100 outputs a signal (hereinafter referred to as CPUout) for control, and controls ON / OFF of the open collector 110, output from the input terminal 50, and ON / OFF of the switch 80.
The CPUout outputs a Hi signal when a high voltage is input from the battery 30 to the inverter 20, and a high voltage OFF signal from the vehicle 30 when the battery switch of the battery 30 is turned off and the inverter 20 receives a high voltage OFF signal from the vehicle side. When the voltage is cut off, Lo signal is output.
When the Hi signal is output, the open collector 110 is ON, the output from the input terminal 50 is approximately 0 V, the switch 80 is OFF, and when the Lo signal is output, the open collector 110 is OFF and the input terminal The output from 50 is open and the switch 80 is ON.

FIG. 3 is a chart showing the case classification of the control processing of the control unit of the electric circuit according to the present embodiment. The control processing is divided into patterns according to the operation of the microcomputer 100 and the presence / absence of power input from the battery 30. Hereinafter, the discharge in each pattern will be described.
<Pattern 0: When the microcomputer operates normally and a high voltage is input from the battery>
When the microcomputer 100 operates normally and a high voltage is input from the battery 30 to the inverter 20, that is, when the capacitor 40 is discharged in a normal operating state, a Hi signal is output from the microcomputer 100. . Therefore, the open collector 110 is ON, the output from the input terminal 50 is about 0 V, and the switch 80 is OFF. Here, since the input terminal 50 is about 0 V, the resistance value of the resistor 90 is approximately 0Ω between the ground and the input terminal 50, that is, the resistance 90. Therefore, the resistance value of the first wiring is only the resistance value (900 kΩ) of the first resistor 60, and the capacitor 40 and the first resistor 60 are equivalently connected. The capacitor 40 is discharged by the first resistor 60. Is done. Further, since the switch 80 is OFF, the current of the capacitor 40 does not flow through the second wiring, and the second resistor 70 is not discharged.

<Pattern 1: When the microcomputer operates normally and the high voltage from the battery is cut off>
Although the microcomputer 100 is operating normally, the microcomputer 100 outputs a Lo signal when the capacitor 40 is discharged when the battery switch of the battery 30 is turned off and the inverter 20 receives a high voltage OFF signal from the vehicle side. Is done. Therefore, the open collector 110 is OFF and the output from the input terminal 50 is open.
At this time, the voltage of the input terminal 50 is determined by dividing the voltage of the first resistor 60 and the resistor 90. In the present embodiment, the resistance value of the first resistor 60 is 900 kΩ, the resistance value of the resistor 90 is 80 kΩ, and the voltage at the input terminal 50 is a resistance divided by these resistors. The voltage of the input terminal 50 is equal to the voltage of Vg on the electric circuit 1, and the switch 80 is turned on when the voltage of Vg is equal to or higher than the gate threshold value of the switch 80. That is, the resistance values of the first resistor 60 and the resistor 90 are selected such that the voltage Vg determined by the resistance voltage division is equal to or higher than the gate threshold value of the switch 80.
When the switch 80 is turned ON, the second circuit including the second resistor 70 is connected in parallel with the capacitor 40, and the resistance value of the second circuit is compared with the resistance value of the first circuit including the first resistor 60 (this embodiment). In this configuration, the capacitor 40 and the second resistor 70 are equivalently connected to each other, and the current of the capacitor 40 does not flow through the first circuit but flows through the second circuit having the second resistor 70. It is discharged by the resistor 70. Therefore, the electrical energy of the capacitor 40 is discharged faster than when the current of the capacitor 40 flows through the first circuit and is discharged.
The second resistor 70 is a resistor having a resistance value lower than that of the first resistor 60 and having a smaller power capacity. In this embodiment, for example, resistors 70a, 70b, and 70c having a resistance value as low as 22 kΩ are connected in series. It is said.

<Pattern 2: When the microcomputer is deactivated and the high voltage from the battery is cut off>
The microcomputer 100 operates with a voltage converted from a low-voltage power supply (for example, 12V system) on the vehicle side. When the low-voltage power supply on the vehicle side is cut off, control by the microcomputer 100 cannot be performed. As described above, when the microcomputer is inoperative, the signal from the microcomputer 100 is switched from the Hi signal to the Lo signal. Therefore, the open collector 110 is OFF, the output from the input terminal 50 is open, and the switch 80 is ON. Thereby, the second circuit including the second resistor 70 is connected in parallel with the capacitor 40, and the resistance value (66 kΩ) of the second circuit is lower than that of the first circuit including the first resistor 60. The second resistor 70 is equivalently connected to the circuit, and the current of the capacitor 40 does not flow through the first circuit but flows into the second circuit having the second resistor 70 and is discharged by the second resistor 70.
As described above, even when the microcomputer 100 is not operated and the high voltage from the battery is cut off, the capacitor 40 can be discharged.

Next, a conventional electric circuit as a reference example will be described with reference to FIG.
FIG. 4 shows a schematic configuration diagram of a conventional electric circuit as a reference example of the present invention.
As shown in FIG. 4, a conventional electric circuit 5 as a reference example includes a motor 10, an inverter 20, a battery 30, a capacitor 40, and a resistor 200 as main components.

The conventional electric circuit 5 performs discharge by connecting a resistor 200 as a resistor in parallel with the capacitor 40. The discharge time (discharge time constant) τ at this time is expressed by the following equation (1).
τ = C × R (1)
In order to prevent an electric shock or a short circuit accident to the human body, it is better to shorten (shorten) the discharge time of the capacitor 40. For this purpose, it is necessary to reduce the value of the resistor, that is, the resistor 200. When the value of the resistor 200 is decreased, the battery 30 is connected in parallel and thus the battery 30 is continuously discharged, the power capacity required for the resistor 200 to maintain the voltage is increased, and the resistor 200 is enlarged. . The inverter of the vehicular electric compressor is required to be as small as possible. However, when it is desired to shorten the discharge time of the capacitor 40 for safety reasons as described above, the resistor 200 and thus the inverter 20 It is necessary to increase the size, which contradicts the size reduction of the electric compressor.
Conversely, if the resistance 200 is prioritized for downsizing and is changed to one having a smaller power capacity, the resistance value of the resistor 200 increases, and the discharge time cannot be shortened, resulting in a safety problem.

As described above, according to the electric circuit, the electric compressor, and the control method of the electric circuit according to the present embodiment, the following operational effects can be obtained.
When the voltage is applied to the capacitor 40 by the battery 30, the discharge current of the capacitor 40 flows through the first wiring, and when the voltage to the capacitor 40 is cut off, the discharge current of the capacitor 40 flows through the second wiring. For this reason, when discharging the electric energy stored in the capacitor 40, it is possible to perform discharge for an appropriate discharge time according to ON / OFF of the battery 30. In particular, when the voltage from the battery 30 is cut off due to an unexpected situation such as interruption of the battery 30, disconnection of the high-voltage cable connected to the battery 30, removal of the high-voltage connector, etc. Since the discharge is performed by the two resistors 70, the discharge time is shorter than when the first wiring is selected, so that the occurrence of a short circuit accident or the like can be prevented. Further, since the second resistor 70 is a resistor having a low power capacity, it is possible to use a small component, and thus it is possible to prevent the electric circuit 1 from being enlarged.
In this embodiment, the number of resistors is increased as compared with the conventional example, but the circuit area is reduced by optimizing the size, cost, and power capacity of the resistors. Therefore, since the circuit area of the electric circuit 1 can be reduced, the installation area and the manufacturing cost can be reduced.

  In addition, a switch 80 for switching between the first wiring and the second wiring is provided, and the discharge current flows through the second wiring when the switch 80 is ON, and flows through the first wiring when the switch 80 is OFF. The wiring can be switched by a simple method of turning ON / OFF the switch 80 according to the presence or absence of voltage application.

  Further, since the switch 80 is turned ON / OFF by the signal output from the microcomputer 100, that is, the first wiring and the second wiring are switched, the battery 30 is disconnected, the high voltage cable connected to the battery 30 is disconnected, When the voltage input is cut off due to the removal of the high voltage connector or the like, the microcomputer 100 outputs a signal corresponding to it, and the switching to the second wiring is performed. Therefore, the discharge time is longer than when the first wiring is selected. The short second resistor 70 can be selected.

  Further, when the microcomputer 100 is not operated, the switch 80 is turned ON, so that even if the microcomputer 100 is not operated due to an unexpected situation such as the power supply being cut off, the control by the microcomputer 100 cannot be performed. When the voltage input from the battery 30 is cut off, the second wiring is selected because the switch 80 is ON, and the discharge time is longer than when the first wiring is selected by the second resistance 70 having a low resistance value. A short discharge can be performed. That is, even if the control by the microcomputer 100 cannot be performed, when the voltage input from the battery 30 is cut off, the capacitor 40 can be automatically and safely discharged at high speed.

  In addition, since the electric compressor includes any of the electric circuits described above, when discharging the electric energy stored in the capacitor 40 of the electric compressor, an appropriate discharge corresponding to ON / OFF of the battery 30 is performed. Time discharge can be performed. In particular, when the voltage from the battery 30 is cut off due to an unexpected situation such as interruption of the battery 30, disconnection of the high-voltage cable connected to the battery 30, removal of the high-voltage connector, etc. Since the discharge is performed by the two resistors 70, the discharge time is shortened, so that the occurrence of a short circuit accident or the like can be prevented.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

  For example, in the above-described embodiment, the resistance 70 of the second wiring is such that the resistors 70a, 70b, and 70c are connected in series. However, the resistance value is lower than that of the first wiring and the area of the circuit board must not be affected. For example, two or less or four or more resistors may be used, or they may be connected in parallel.

DESCRIPTION OF SYMBOLS 1, 5 Electric circuit 10 Motor 20 Inverter 30 Battery 40 Capacitor 50 Input terminal 60 1st resistance 70 2nd resistance 80 Switch 90, 200 Resistance 100 Microcomputer (control part)
110 Open collector

Claims (6)

A capacitor connected to the battery;
A first wiring having a first resistor placed in parallel with the capacitor;
A second wiring having a second resistance having a resistance value lower than that of the first resistance installed in parallel with the capacitor;
With
When a voltage is applied to the capacitor by the battery, the discharge current of the capacitor flows through the first wiring, and when the voltage to the capacitor by the battery is cut off, the discharge current of the capacitor is An electric circuit characterized by flowing in the second wiring.   A switch that switches between selection of the first wiring and the second wiring; when the switch is ON, the discharge current of the capacitor flows through the second wiring; when the switch is OFF, the discharge current of the capacitor is The electric circuit according to claim 1, wherein the electric circuit flows through the first wiring.   3. The electric circuit according to claim 1, further comprising a control unit that outputs a signal for controlling ON / OFF of the switch in accordance with whether or not voltage is applied from the battery to the capacitor. 4.   The electric circuit according to claim 1, wherein the switch is turned on when the control unit is not operated.   An electric compressor provided with the electric circuit according to any one of claims 1 to 4. A capacitor connected to the battery;
A first wiring having a first resistor placed in parallel with the capacitor;
A second wiring having a second resistance having a resistance value lower than that of the first resistance installed in parallel with the capacitor;
With
When a voltage is applied to the capacitor by the battery, a step of flowing a discharge current of the capacitor through the first wiring; and when a voltage to the capacitor by the battery is interrupted, a discharge current of the capacitor Flowing to the second wiring;
A method for controlling an electric circuit, comprising:

Images