JPH04198769A - Protecting method for switching element at defective contact of hct - Google Patents

Abstract

PURPOSE:To protect a switching element from damage due to an overcurrent by detecting the current value applied to a pin via a resistor. CONSTITUTION:If the contact state of a connector 11 is good, when a RUN signal is inputted to a NAND circuit 15, a gate ENABLE signal is inputted to a gate circuit 16, thus a switching element is driven by the gate drive signal of the circuit 16. If the contact state of the connector 11 is not good, the termi nal voltage of a resistor R1 does not reach the preset voltage, when the RUN signal is inputted to the circuit 15, the gate ENABLE signal is not outputted effectively. The circuit 16 is not turned on, and the switching element of an inverter is protected from the the breakage due to an overcurrent based on a defective feedback caused by the defective contact of the connector 11.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of Application The present invention is directed to an inverter device that uses a Hall current detector (HCT) to perform current control in a closed loop. The present invention relates to a method for protecting switching elements from damage.

B0 Summary of the Invention The present invention provides an HCT connector with a pair of pins connected to the HCT cable side housing, applies a voltage to the pin circuit through a resistor, detects the current, and determines the contact state of the connector. The current flowing through the power supply to the HCT is detected to determine whether it is within the normal operating range of the HCT, and the gate of the switching element of the inverter is shut off using the determination result to detect a faulty HCT connection. This prevents excessive current from flowing through the switching element.

C9 Conventional technology As shown in Figure 3, an inverter device that performs current control in a closed loop using a current detector uses the output current command value calculated inside the microcomputer and the feedback of the current output current value from the current detector. It forms a closed loop that determines the output current. A Hall CT (hereinafter simply referred to as HCT) is generally used for this current detector.
and the control circuit are connected by a connector.

D0 Problem to be Solved by the Invention In the above closed loop, when the inverter is started, it outputs a current, but if the HCT connector wired from the HCT is disconnected, the detected current value will be 0, so the current command will be the output current. move in the direction of increasing. As a result, the output current increases rapidly.

Overcurrent protection uses this current detection value, so HC
If the T connector is disconnected, overcurrent detection will not be possible and the output current will exceed the rating of the switching element, resulting in damage.

The present invention was made in view of these conventional problems, and its purpose is to protect the switching elements of the inverter from destruction even when the HCT connector is operated without being wired. An object of the present invention is to provide a method for protecting a switching element when an HCT connection is defective.

Means for Solving the E0 Problem In order to achieve the above object, the method of protecting the switching element in the event of an HCT connection failure in the present invention feeds back the detected current of the HCT to the control circuit via the connector and controls the current in a closed loop. In an inverter device using a CPU, a pair of pins connected to the HCT cable side of the housing is provided in the connector, a voltage is applied to the pin circuit through a resistor, and a current flowing through the pair of pin circuits is detected. , determines whether the contact state of the connector is good or bad based on the detected current value, and uses the determination result to shut off the gate of the switching element of the inverter.

Also, it detects the current flowing in the current supplied to the HCT, determines whether the detected current value is within the range of normal operation of the HCT, and uses the determination result to shut off the gate of the switching element of the inverter. You may also do so.

Then, the determination result can be imported into the CPU and display a wiring defect in the HCT circuit.

Assuming that the F0-acting HCT connector has a pair of pins connected by a housing, if voltage is applied to the pair of pins through a resistor, the current value will be detected because the current changes depending on the contact state of the connector. By doing so, it is possible to judge whether the contact state of the connector is good or bad.

In addition, since the current flowing through the power supply to the HCT changes depending on the contact state of the HCT connector, this current is detected,
By determining whether the current value is within the normal operating range of the HCT, it is possible to determine whether the contact state of the connector is good or not.

Therefore, if the gate of the switching element of the inverter is cut off when the contact state of the connector is determined to be defective as described above, overcurrent in the switching element due to poor feedback from the HCT can be prevented and the switching element can be protected. I can do it.

G. Example Embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 In FIG. 1, reference numeral 11 denotes an HCT connector consisting of a pin 12 on the board side and a housing 13 on the cable side. The 1st to 4th pins of the connector 11 are for the HCT circuit, the 5th and 6th pins are connector contact state detection pins connected by the wire 14 in the housing 13, and the 5th pin is connected to the control circuit power supply +15V. The 6th pin is connected to the power supply 0v via a resistor R1.

, 15 is a NAND that determines whether the contact state of the connector is good or bad.
In the circuit, the terminal voltage of resistor R1 and the run signal to operate the inverter are input, and if the contact state of the connector is good, when the run signal is input, the gate enable (
ENABLE) signal is output, and if the contact state is defective, the gate enable signal is not output even if the run signal is input. 16 is a gate circuit that drives the switching elements of the inverter, and the gate pulse from the gate pulse generation circuit (not shown) and the NAND circuit 15
The gate enable signal from the

Therefore, when the contact state of the connector 11 is good, when the run signal is input to the NAND circuit, the gate enable signal is input to the gate circuit 16, so the switching element is driven by the gate drive signal of the gate circuit 16, and the contact of the connector 11 is If the condition is defective, the terminal voltage of the resistor R1 does not reach a predetermined voltage, so even if a run signal is input to the NAND circuit 15, a gate enable signal is not effectively output.

Therefore, since the gate circuit 16 has no ONL, the switching elements of the inverter are protected from damage due to overcurrent due to poor feedback due to poor contact of the connector.

Embodiment 2 In FIG. 2, 20 is an HCT, 21 is a normal HCT connector, 22 is a current detection circuit into which the HCT output is input, 23 is a current command circuit, and 24 is a current command and current of the current command circuit 23. A gate pulse generation circuit generates a gate pulse from the detection current of the detection circuit 22, 25 is a gate circuit to which the gate pulse from the gate pulse generation circuit 24 is input and drives the switching element of the inverter, and 26 is for the Ushinecta's ten power supply circuit. A resistor that detects the current of the power supply supplied to the HCT inserted between the pin and the control power supply +15V,
26 is a differential amplifier into which the terminal voltage of resistor R2 is input; 27
is the control power supply +15V for the output of the differential amplifier 26 and the resistor R3.
This is a comparator that compares the voltage with the reference voltage divided by R4 and outputs a gate enable signal for the gate circuit 25.

Therefore, if the contact state of the connector 21 is good, the HC
A predetermined current flows through the power supply +15V circuit of T20, and the resistor R
Since the type voltage between both terminals of the inverter 2 becomes a predetermined voltage, a gate enable signal is effectively output to the comparator 27, the gate circuit 25 becomes conductive, and the switching element of the inverter is driven.

If the contact state of the connector 21 is poor, the specified current will not flow in the power supply +15V circuit of the HCT 20, and the type voltage between both terminals of the resistor R2 will not reach the specified voltage, so the comparator 2
7, the gate enable signal is not output effectively. Therefore, since the gate circuit 25 is not turned on, the switching elements of the inverter are protected from damage due to overcurrent due to poor feedback due to poor contact of the connector.

By taking the enable signals in Examples 1 and 2 into the CPU (not shown), the HCT connector or HCT
It is possible to display circuit defects.

H1 Effects of the Invention Since the present invention is configured as described above, it produces the following effects.

■ Even if the inverter is operated with a poor connection of the HCT connector, the enable signal connected to the gate circuit will not become valid, and the gate circuit will not be ONL. Therefore, the switching element can be protected from destruction due to overcurrent when the connector is poorly connected.

(2) According to the method of claim (2), there is no need to increase the number of pins of the connector, and it can be applied to devices using conventional connectors, and is highly practical.

In addition, the contact state of the connector can be changed to H without increasing the number of pins.
Since the CT power supply current is used, connection failures in the HCT circuit can be reliably detected.

(2) According to the method of claim (3), defective locations can be quickly recognized.

[Brief explanation of the drawing]

1 and 2 are block circuit diagrams showing switching element protection circuits used in the methods of embodiments 1 and 2 of the present invention, respectively, and FIG. 3 is an explanatory diagram of the current control loop of the inverter. 1.16.25...Gate circuit, 2...Switching element, 3...Motor, 11.21...Connector,
12...Pin, 13...Housing, 15...N
AND circuit, 4, 20... HCT, 22... Current detection circuit, 23... Current command circuit, 24... Gate pulse generation circuit, 26... Differential amplifier, 27... Comparator.

Claims (3)

[Claims] (1) In an inverter device using a CPU that feeds back the detected current of the HCT to the control circuit via a connector and controls the current in a closed loop, the connector is provided with a pair of pins connected by the housing on the HCT cable side, and the pins are A voltage is applied to the circuit through a resistor, the current flowing through the pair of pin circuits is detected, and the detected current value is used to judge whether the contact state of the connector is good or not.The judgment result is used to control the gate of the switching element of the inverter. A method for protecting a switching element in the event of a poor HCT connection, the method comprising: blocking the switching element; (2) A CPU that feeds back the detected output current of the HCT to the control circuit via the connector and controls the current in a closed loop.
In the inverter device using the HCT, the current flowing to the HCT is detected, and the detected current value
1. A method for protecting a switching element in the event of an HCT connection failure, the method comprising determining whether or not the voltage is within a normal operating range, and using the determination result to shut off a gate of a switching element of an inverter. (3) A method for protecting a switching element at the time of a poor HCT connection, characterized in that the determination result is loaded into the CPU and a defective wiring of the HCT circuit is displayed.