JPH08266087A - Inverter device - Google Patents

Abstract

PURPOSE: To transmit the signals for the control of a DC brushless motor, etc., without affecting its control circuit. CONSTITUTION: A primary winding 4a of a current sensor 4 is provided between a high-voltage battery 1 and an inverter portion 3, and a flywheel diode 5 of reverse polarity is connected in parallel with the primary winding 4a, and by a Hall element 4b the current of the inverter portion 3 is sensed. Responding to the control signals from an ECU 8, a motor control portion 7 controls a DC brushless motor 6 on the basis of the sensed current. Surge-voltages in case of IGBTs 30 turning off are not applied to the IGBTs 30. Also, the motor control portion 7 protects the IGBTs 30 from their overcurrents, and computes the currents of the motor 6 and the consumption current of the inverter portion 3. Therefore, the signals for the protection of the motor 6 and various controls can be transmitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter control device for controlling energization of a motor, and to a device provided with a current sensor for detecting the current of an inverter circuit.

[0002]

2. Description of the Related Art In an inverter control device for controlling energization of a motor, in order to detect an induced voltage of a motor winding for detecting a rotational position of the motor and to control a timing of energizing the winding of the motor, For example, JP-A-6-9858
As described in Japanese Patent No. 3, a shunt resistor is connected to the DC bus between the DC power supply and the inverter circuit to detect the current.

[0003]

However, in the case where the motor is driven by a high-voltage main power source such as an electric vehicle,
It is necessary to convert the signal for detecting the rotational position of the motor from a high voltage of the motor drive circuit to a low voltage that can be processed by the control circuit. Further, in the inverter device, not only the overcurrent protection of the motor but also the circuit protection when the upper and lower arms of the inverter circuit are short-circuited is required. It is impossible in terms of circuit configuration to directly transmit such signals for some purposes from the circuit element provided in the motor or the inverter circuit for energizing the motor to the control circuit as described above.

Therefore, it is conceivable that a current sensor is connected to the DC bus to detect a short circuit between the upper and lower arms, and the motor current is calculated from the current detected by the current sensor to protect the motor from overcurrent. . However, when the current sensor is used, when the switching element is turned off, a surge voltage exceeding the withstand voltage of the switching element is generated due to the inductance of the winding of the current sensor. Therefore, there is a problem that noise increases and the control circuit malfunctions or the switching element is damaged.

According to the present invention, in an inverter device for driving and controlling a motor, signals for controlling the motor and various protection operations are reliably transmitted to the motor control circuit without affecting the operation of the motor control circuit. With the goal.

[0006]

According to the present invention, claim 1
An inverter circuit provided between the DC power source and the motor, the inverter circuit including a plurality of switching elements for sequentially energizing windings of a plurality of phases of the motor, and connected in series between the DC power source and the inverter circuit. A current sensor for detecting a current flowing through the inverter circuit, the current sensor including a current detection winding and a magnetic sensor provided in a non-contact manner with the current detection winding, and parallel to the current detection winding of the current sensor. And the diode connected in reverse polarity to the current flowing from the DC power supply to the inverter circuit,
The technical means comprises a motor control circuit that controls the plurality of switching elements of the inverter circuit based on the current detected by the current sensor.

According to a second aspect of the present invention, the motor control circuit performs at least one operation of an overcurrent protection control operation of the switching element, an operation operation of the motor current, and a consumption current operation operation of the inverter circuit. The technical means is to carry out based on the output of the current sensor.

[0008]

According to the present invention, in the motor control circuit, the motor control circuit includes a current detection winding connected in series between the DC power supply and the inverter circuit, and a magnetic field provided in the current detection winding in a non-contact manner. The switching element of the inverter circuit is controlled based on the current flowing through the inverter circuit, which is detected by the current sensor including the sensor. When the switching element is turned off, an induced voltage is generated due to the inductance of the current detection winding of the current sensor, but it is connected in parallel with the current detection winding in reverse polarity to the current flowing from the DC power supply to the inverter circuit. Since it is returned to the diode, the surge voltage at turn-off is absorbed, noise is not generated, and the surge voltage is not applied to the switching element.

According to another aspect of the present invention, the motor control circuit performs at least one of overcurrent protection control operation of the switching element, motor current calculation operation, and consumption current calculation operation of the inverter circuit based on the output of the current sensor. Take action. Therefore, the signal for each operation is not obtained from the circuit element connected to the inverter circuit, but is obtained by the non-contact magnetic sensor, so that the insulation between the inverter circuit and the motor control circuit is ensured and noise is mixed. And stable control operation can be secured.

[0010]

As described above, according to the present invention, since the diode of the opposite polarity is connected in parallel to the current detection winding connected between the DC power supply and the inverter circuit, when the switching element is turned off, the surge voltage is reduced. Does not add to the switching element or generate noise. Therefore, the current sensor can reliably transmit signals for motor control and various protection operations to the motor control circuit without affecting the operation of the motor control circuit.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An inverter device 100 for driving an electric compressor for an air conditioner of an electric vehicle shown in FIG. In FIG. 1, 1 is a direct current 28
It is a high voltage battery with a voltage of 8 [V] and is also a power source for running an electric vehicle. Reference numeral 2 is a capacitor for voltage stabilization, 3 is an inverter unit in which a plurality of IGBTs 30 are used as switching elements and is bridge-connected with a plurality of diodes D, 4 is a current sensor for detecting a current flowing through the inverter unit 3, and a primary winding 4a And a Hall element 4b for non-contact detection of a magnetic field generated by energization of the primary winding 4a.
Consists of Reference numeral 5 is a flywheel diode for freewheeling, which is connected in parallel in a direction opposite to the current direction of the primary winding 4a of the current sensor 4, and 6 is a DC load of the inverter unit 3.
It is a brushless motor.

Reference numeral 7 is a motor control unit for issuing an ON / OFF control signal to the IGBT 30 which is a switching element of the inverter unit 3 and for monitoring the operating state of the DC brushless motor 6 based on the detection signal of the current sensor 4, and 8 is an inverter. The start, stop, and rotation speed commands are output to the motor control unit 7 of the unit 3, and the monitoring signal from the motor control unit 7 is used as a feedback signal to set a temperature by an operation panel (not shown), various temperature sensors, and other The ECU optimally controls the inverter unit 3 based on the detection signal.
Reference numeral 9 is a control power supply for operating the motor control unit 7 and the ECU 8.

Next, the motor controller 7 will be described with reference to FIG. The motor controller 7 includes an amplifier 10 for amplifying the output voltage of the Hall element 4b of the current sensor 4, and a comparator 1 for inverting the output when the output voltage of the amplifier 10 exceeds a threshold value.
1. High voltage battery 1 based on output signal of amplifier 10
An input current calculation circuit 12 for calculating a consumption current (effective current value) flowing from the inverter unit 3 to the inverter unit 3, and a current value actually flowing in the DC brushless motor 6 during PWM control by the amplifier 1
Starting the ECU 8 while monitoring the outputs of the motor current calculation circuit 13, which is an averaging circuit composed of a resistor and a capacitor, the input current calculation circuit 12, and the motor current calculation circuit 13 for calculation based on the output signal of 0, A microcomputer 14 that sends out a PWM control signal for controlling the DC brushless motor 6 based on a stop and rotation speed command;
A gate drive circuit 15 that outputs a gate signal for driving the DC brushless motor 6 according to the PWM control signal of the microcomputer 14 and stops the drive of the DC brushless motor 6 when the output of the comparator 11 is inverted. .

Next, the operation of the inverter device 100 of the present embodiment having the above configuration will be described. Motor control unit 7
Starts the inverter unit 3 in response to a command from the ECU 8,
PW so that the DC brushless motor 6 reaches the target speed
M control. At this time, in the inverter unit 3, a voltage having a waveform as shown in FIG. 3 appears between the points P and N of the inverter unit 3 in response to the ON / OFF operation of the IGBT 30, which is a switching element, and the current sensor 4 A current having a waveform as shown in FIG.

In FIG. 3, PWM is performed between point A and point B.
The inverter unit 3 supplies a current for driving the DC brushless motor 6 under control, and the current supply from the inverter unit 3 to the DC brushless motor 6 is stopped between the point B and the point A. The current from point B to point C is a current that appears when the counter electromotive voltage generated by the inductance L1 of the primary winding 4a of the current sensor 4 flows through the flywheel diode 5 when the IGBT 30 is turned off. In this way, when turning off, the current sensor 4
By circulating the counter electromotive voltage generated by the inductance L1 of the primary winding 4a by the flywheel diode 5, the surge voltage between the points P and N of the inverter unit 3 is significantly reduced. The motor current calculated by the motor current calculation circuit 13 appears so as to connect between the point B and the next point A as shown by the alternate long and short dash line in FIG.

For comparison, FIG. 4 shows the voltage between points P and N and the current detected by the current sensor 4 when the flywheel diode is not used in the inverter control device of this embodiment. When the flywheel diode is not used, a surge voltage is generated in the voltage between points P and N at the time of turn-on (point A) and turn-off (point B) of the IGBT 30, especially at turn-off (point B). A large surge voltage has occurred. On the other hand, in the present embodiment using the flywheel diode 5, it can be seen that the surge voltage at the time of turn-on (point A) of the IGBT 30 hardly appears and the surge voltage at the time of turn-off (point B) can be significantly reduced.

As described above, according to this embodiment, the flywheel diode 5 having the opposite polarity is connected in parallel to the primary winding 4a of the current sensor 4 connected between the high voltage battery 1 and the inverter section 3. Therefore, when the IGBT 30 is turned off, a surge voltage is not applied to the IGBT 30 and noise is not generated. Therefore, the hall element 4b reliably transmits signals for controlling the DC brushless motor 6 and various protective operations to the microcomputer 14 without affecting the operation of the microcomputer 14 of the motor control unit 7 as a motor control circuit. can do. Although the Hall element is used in the above embodiment, a magnetoresistive element may be used.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an inverter control device showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a motor control unit according to the embodiment of the present invention.

FIG. 3 is a time chart for explaining the operation of the embodiment of the present invention.

FIG. 4 is a comparative time chart according to another configuration for explaining the operation of the embodiment of the present invention.

[Explanation of symbols]

 1 High Voltage Battery (DC Power Supply) 3 Inverter Section (Inverter Circuit) 30 IGBT (Switching Element) 4 Current Sensor 4a Primary Winding (Current Detection Winding) 4b Hall Element (Magnetic Sensor) 5 Flywheel Diode (Diode) 6 DC brushless motor (motor) 7 Motor control circuit (motor controller)

Claims (2)

[Claims] 1. An inverter circuit, which is provided between a DC power supply and a motor, and includes a plurality of switching elements for sequentially energizing windings of a plurality of phases of the motor, and between the DC power supply and the inverter circuit. A current sensor for detecting a current flowing in the inverter circuit, the current sensor including a current detection winding connected in series to the current detection winding and a magnetic sensor provided in the current detection winding in a non-contact manner, and the current detection of the current sensor. A diode connected in parallel with the winding for use and having a reverse polarity to the current flowing from the DC power supply to the inverter circuit, and controlling the plurality of switching elements of the inverter circuit based on the current detected by the current sensor. Inverter device comprising a motor control circuit for 2. The motor control circuit performs at least one operation of an overcurrent protection control operation of the switching element, an operation operation of the motor current, and an operation operation of consumption current of the inverter circuit, The inverter device according to claim 1, which is performed based on an output.