JPWO2020194623A1 - Motor drive controller - Google Patents

Abstract

The motor drive control device (100) includes an inverter circuit (2) composed of a switching element that controls energization of the motor (1), a gate drive circuit (15) that drives the switching element based on a drive signal, and the like. The first protection circuit (21) that cuts off the power supply to the gate drive circuit and stops the operation of the inverter circuit when the detected value of the current flowing through the motor exceeds the threshold value, and the detected value exceeds the threshold value. It is provided with a second protection circuit (22) that cuts off the input of the drive signal to the gate drive circuit in such a case.

Description

The present invention relates to a motor drive control device that drives and controls a motor.

A motor drive control device that drives and controls a motor generally includes a protection circuit that prevents an overcurrent from flowing through the motor.

In Patent Document 1, by providing two protection circuits, even if one protection circuit fails, the other protection circuit stops the gate signal of the switching element to prevent an overcurrent from continuing to flow in the motor. The drive circuit is described.

Japanese Unexamined Patent Publication No. 2011-139612

The invention described in Patent Document 1 can protect the motor by detecting a state in which an overcurrent flows through the motor even if one of the protection circuits fails. However, when an overcurrent is detected, the drive circuit is controlled to stop the operation of the switching element so that no current flows. Therefore, the drive circuit that drives the switching element of the inverter circuit fails, and the switching element fails. If the drive of the inverter cannot be controlled, there is a problem that the state in which the overcurrent flows cannot be eliminated.

The present invention has been made in view of the above, and obtains a motor drive control device capable of eliminating a state in which an overcurrent flows through a motor even when the drive circuit for driving the switching element of the inverter circuit fails. The purpose is.

In order to solve the above-mentioned problems and achieve the object, the motor drive control device according to the present invention drives an inverter circuit composed of a switching element for controlling energization of a motor and a switching element based on a drive signal. It is equipped with a gate drive circuit. Further, the motor drive control device has a first protection circuit that cuts off the power supply to the gate drive circuit and stops the operation of the inverter circuit when the detected value of the current flowing through the motor exceeds the threshold value, and the detected value. A second protection circuit for blocking the input of the drive signal to the gate drive circuit when the value becomes equal to or higher than the threshold value is provided.

The motor drive control device according to the present invention has an effect that the state in which an overcurrent flows through the motor can be eliminated even if the drive circuit for driving the switching element fails.

The figure which shows an example of the circuit structure of the motor drive control device which concerns on Embodiment 1. FIG. 6 is a diagram showing a configuration example of a main part of a first protection circuit included in the motor drive control device according to the first embodiment. The figure which shows the operation example of the main part of the 1st protection circuit provided in the motor drive control device which concerns on Embodiment 1. FIG. 6 is a diagram showing a configuration example of a main part of a first protection circuit included in the motor drive control device according to the second embodiment. A flowchart showing an example of the operation of the first protection circuit included in the motor drive control device according to the second embodiment.

Hereinafter, the motor drive control device according to the embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

Embodiment 1.
FIG. 1 is a diagram showing an example of a circuit configuration of the motor drive control device according to the first embodiment.

As shown in FIG. 1, the motor drive control device 100 according to the first embodiment drives and controls the motor 1.

The motor drive control device 100 includes an inverter circuit 2, a gate drive power supply 8, a gate signal generation unit 14, a gate drive circuit 15, a first protection circuit 21, and a second protection circuit 22.

The inverter circuit 2 is composed of a plurality of switching elements that control energization of the motor 1, and generates electric power to be supplied to the motor 1. The switching element is a semiconductor switch such as an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal Oxide Semiconductor Field Effect Transistor). The gate drive power supply 8 generates electric power supplied by the gate drive circuit 15. The gate signal generation unit 14 generates a drive signal for driving the switching element included in the inverter circuit 2. The gate drive circuit 15 drives the switching element of the inverter circuit 2 based on the drive signal generated by the gate signal generation unit 14 to control the operation of the inverter circuit 2. When the first protection circuit 21 detects a state in which an overcurrent flows through the motor 1, it cuts off the power supply to the gate drive circuit 15 and stops the operation of the inverter circuit 2. When the second protection circuit 22 detects a state in which an overcurrent flows through the motor 1, the second protection circuit 22 cuts off the input of the drive signal to the gate drive circuit 15 and stops the operation of the inverter circuit 2.

The first protection circuit 21 includes a current detection unit 3, an overcurrent detection circuit 5, a latch circuit 6, a holding circuit 7, and a switch 12. The second protection circuit 22 includes a current detection unit 4, a latch circuit 9, a holding circuit 10, an overcurrent detection circuit 11, and a buffer circuit 13.

The current detection units 3 and 4 detect the current flowing from the inverter circuit 2 to the motor 1. The current detection units 3 and 4 are composed of a current transformer, a shunt resistor, and the like. In the following description, the current flowing from the inverter circuit 2 to the motor 1 may be referred to as a motor current.

The overcurrent detection circuits 5 and 11 detect a state in which the motor current is excessive, that is, a state in which the motor current is equal to or higher than a predetermined threshold value. The latch circuits 6 and 9 latch and output the state of the input signal when a signal indicating that a state in which the motor current has become excessive is detected is input. In the following description, a state in which the current flowing from the inverter circuit 2 to the motor 1 becomes excessive may be referred to as an overcurrent state.

The holding circuit 7 controls the latch circuit 6 so that the state in which the latch circuit 6 latches and outputs the input signal continues for a certain period of time, that is, the state in which the overcurrent state is detected continues to be output for a certain period of time. do. The holding circuit 10 controls the latch circuit 9 so that the state in which the latch circuit 9 latches and outputs the input signal continues for a certain period of time, that is, the state in which the overcurrent state is detected continues to be output for a certain period of time. do. The switch 12 is provided between the gate drive power supply 8 and the gate drive circuit 15, and when the input signal from the latch circuit 6 indicates that an overcurrent state has been detected, the gate drive circuit from the gate drive power supply 8 is provided. The power supply path to the gate 15 is opened to cut off the power supply to the gate drive circuit 15. The switch 12 is composed of an electromagnetic relay or the like. The buffer circuit 13 is provided between the gate signal generation unit 14 and the gate drive circuit 15, and when the input signal from the latch circuit 9 indicates that an overcurrent state has been detected, the gate signal generation unit 14 drives the gate. The drive signal input to the circuit 15 is cut off. The buffer circuit 13 is composed of a logic IC (Integrated Circuit) or the like.

FIG. 2 is a diagram showing a configuration example of a main part of the first protection circuit 21 included in the motor drive control device 100 according to the first embodiment. Specifically, FIG. 2 shows a configuration example of the overcurrent detection circuit 5, the latch circuit 6, and the holding circuit 7 included in the first protection circuit 21. Further, FIG. 3 shows the operation of the main part of the first protection circuit 21 included in the motor drive control device 100 according to the first embodiment, that is, the operation of the overcurrent detection circuit 5, the latch circuit 6 and the holding circuit 7 shown in FIG. It is a figure which shows an example. The configuration and operation of the overcurrent detection circuit 5, the latch circuit 6, and the holding circuit 7 will be described with reference to FIGS. 2 and 3.

The main parts of the second protection circuit 22, specifically, the overcurrent detection circuit 11, the latch circuit 9, and the holding circuit 10, are configured and operated in the overcurrent detection circuit 5 of the first protection circuit 21. It is the same as the latch circuit 6 and the holding circuit 7. Therefore, in the present embodiment, the description of the overcurrent detection circuit 11, the latch circuit 9, and the holding circuit 10 will be omitted.

The operation of the overcurrent detection circuit 5, the latch circuit 6, and the holding circuit 7 will be described.

The overcurrent detection circuit 5 includes a comparator 52. An overcurrent threshold value 51 generated by the control power supply and the voltage dividing circuit is input to the non-inverting input terminal of the comparator 52. A current detection value, which is a signal from the current detection unit 3, is input to the inverting input terminal of the comparator 52. The comparator 52 compares the input current detection value with the overcurrent threshold value 51 and outputs a comparison result. Specifically, the comparator 52 outputs a High level signal when the current detection value is less than the overcurrent threshold value 51, and outputs a Low level signal when the current detection value is the overcurrent threshold value 51 or more. The Low level signal output by the comparator 52 is used as an overcurrent detection signal. In the following description, the Low level signal is represented by “0” and the High level signal is represented by “1”. The output of the comparator 52 becomes the output of the overcurrent detection circuit 5.

The latch circuit 6 is composed of a flip-flop circuit or the like, and a signal output from the overcurrent detection circuit 5 is input to the input terminal S. The output terminals Q and QN of the latch circuit 6 output a signal of a level corresponding to the state of the signal input to each of the input terminals S and R. The output terminal Q is connected to the switch 12. The output terminal QN is connected to the holding circuit 7.

Assuming that the signal states input to the input terminals S and R of the latch circuit 6 are the signals S and R, respectively, and the signal states output by the output terminals Q and QN are the signals Q and QN, respectively, the latch circuit The relationship between each input signal and each output signal of 6 is as follows. That is, when the signal S = 1 and the signal R = 1, the signal Q and the signal QN hold the state, and when the signal S = 1 and the signal R = 0, the signal Q = 0 and the signal QN = 1, and the signal S = 0. When the signal R = 1, the signal Q = 1 and the signal QN = 0, and when the signal S = 0 and the signal R = 0, the signal Q and the signal QN are indefinite.

As shown in FIG. 3, when the overcurrent detection circuit 5 detects an overcurrent state in which an overcurrent flows through the motor 1 and the motor current becomes the overcurrent threshold X or more, the state (input) of the input terminal S of the latch circuit 6 The signal S) is "0", the state of the input terminal R (input signal R) is "0", the state of the output terminal Q (output signal Q) is "1", and the state of the output terminal QN (output signal QN) is. It becomes "0". As a result, the state of the signal input from the latch circuit 6 to the switch 12 becomes "1", and the switch 12 is driven. As a result, the power supply from the gate drive power supply 8 to the gate drive circuit 15 is cut off by the switch 12, the gate drive circuit 15 stops operating, and the inverter circuit 2 is in the protection stop state. When the overcurrent detection circuit 11 of the second protection circuit 22 detects the overcurrent state, the buffer circuit 13 cuts off the output of the gate signal generation unit 14 and puts the inverter circuit 2 in the protection stop state.

The holding circuit 7 includes an RC circuit 71 and a transistor circuit 72. The signal output from the output terminal QN of the latch circuit 6 is input to the RC circuit 71. The signal output by the RC circuit 71 is input to the transistor circuit 72, and the signal output by the transistor circuit 72 is input to the input terminal R of the latch circuit 6.

When the overcurrent detection circuit 5 detects an overcurrent state, the state of the output terminal QN of the latch circuit 6 becomes "0" and the input signal to the RC circuit 71 of the holding circuit 7 also becomes "0" as described above. Become. As a result, the level of the output signal of the RC circuit 71 gradually decreases, and when a time determined by the constants of the resistor R and the capacitor C constituting the RC circuit 71 elapses, the state of the output signal of the transistor circuit 72 changes from "0" to "0". It changes to "1". That is, the state of the input terminal R of the latch circuit 6 changes from "0" to "1", and the latch circuit 6 is reset. Along with this, the state of the output terminal Q of the latch circuit 6 returns to the state before detecting the overcurrent state, and the motor 1 can be re-driven.

As described above, the motor drive control device 100 according to the present embodiment includes the first protection circuit 21 and the second protection circuit 22, and the first protection circuit 21 is the current flowing from the inverter circuit 2 to the motor 1. A switch 12 is provided to shut off the gate drive power supply 8 when an overcurrent state in which is equal to or higher than the overcurrent threshold value X is detected. Further, the second protection circuit 22 includes a buffer circuit 13 that cuts off an output signal from the gate signal generation unit 14 to the gate drive circuit 15 when an overcurrent state is detected. As a result, the inverter circuit 2 can be stopped even if one of the first protection circuit 21 and the second protection circuit 22 fails. Further, since the power supply to the gate drive circuit 15 is stopped to stop the operation of the inverter circuit 2, the motor 1 is connected to the motor 1 when the gate drive circuit 15 fails and the switching element of the inverter circuit 2 cannot be controlled. It is possible to prevent the overcurrent from continuing to flow.

Further, in the motor drive control device 100, since each of the first protection circuit 21 and the second protection circuit 22 includes a current detection unit, an overcurrent detection circuit, a latch circuit, and a holding circuit, one of these parts fails. Even in such a case, the protection circuit including the other one can detect the overcurrent state and stop the operation of the inverter circuit 2.

Further, the motor drive control device 100 includes holding circuits 7 and 10, and resets the latch circuits 6 and 9 when a certain time has elapsed after detecting the overcurrent state to release the operation stop state. Therefore, the motor 1 Can be re-driven.

Embodiment 2.
Next, the motor drive control device according to the second embodiment will be described. The motor drive control device according to the second embodiment has changed a part of the configuration of each protection circuit (first protection circuit 21 and second protection circuit 22) of the motor drive control device 100 according to the first embodiment. It is a thing. Therefore, in the present embodiment, the configuration and operation of each protection circuit, which is a part different from the first embodiment, will be described. Hereinafter, for convenience of description, the motor drive control device, the first protection circuit, and the second protection circuit according to the second embodiment are referred to as the motor drive control device 100a, the first protection circuit 21a, and the second protection circuit 22a, respectively. It is described as.

FIG. 4 is a diagram showing a configuration example of a main part of the first protection circuit 21a included in the motor drive control device 100a according to the second embodiment. The configuration of the second protection circuit 22a is also the same.

As shown in FIG. 4, the main part of the first protection circuit 21a includes an overcurrent detection circuit 5, a latch circuit 6, a holding circuit 7a, and a control circuit 16. Among these components, the overcurrent detection circuit 5 and the latch circuit 6 are the same as the overcurrent detection circuit 5 and the latch circuit 6 of the first protection circuit 21 described in the first embodiment, and the operation is also the same. Is. The control circuit 16 is a microcontroller or the like.

The holding circuit 7a has a configuration in which a switch 73 is added to the holding circuit 7 of the first protection circuit 21 described in the first embodiment. The switch 73 is controlled by the control circuit 16. A signal output from the output terminal QN of the latch circuit 6 is input to the control circuit 16. Based on the input signal from the latch circuit 6, the control circuit 16 determines whether the first protection circuit 21a is in a malfunctioning state in which the operation of repeatedly putting the inverter circuit 2 in the protection stop state is repeated, and detects the malfunctioning state. If so, the operation of the first protection circuit 21a is stopped. The switch 73 is controlled to an off state in a normal state, specifically, in a state in which the protection is not stopped and is not in a malfunctioning state, and the RC circuit 71 of the signal output from the output terminal QN of the latch circuit 6 is controlled. Stop inputting to.

The operation of the first protection circuit 21a will be described with reference to FIG. FIG. 5 is a flowchart showing an example of the operation of the first protection circuit 21a included in the motor drive control device 100a according to the second embodiment.

In the first protection circuit 21a, first, the current detection unit 3 detects the current and inputs the current detection value to the overcurrent detection circuit 5 (step S1). Next, the overcurrent detection circuit 5 compares the current detection value with the overcurrent threshold value (step S2), and when the current detection value is less than the overcurrent threshold value (step S2: No), the process returns to step S1.

When the current detection value is equal to or greater than the overcurrent threshold value (step S2: Yes), the latch circuit 6 operates, and the holding circuit 7a holds the abnormal state accordingly (step S3). "The holding circuit 7a holds an abnormal state" means that the holding circuit 7a does not change the state of the output signal to the latch circuit 6 even if the state of the input signal from the latch circuit 6 changes. It means to keep the state.

Further, the latch circuit 6 drives the switch 12 (see FIG. 1) and shuts off the gate driving power supply 8 (step S4). That is, the first protection circuit 21a cuts off the power supply from the gate drive power supply 8 to the gate drive circuit 15 and stops the control of the inverter circuit 2 by the gate drive circuit 15.

Next, the control circuit 16 confirms whether the first protection circuit 21a repeats the overcurrent protection operation (step S5). The control circuit 16 determines whether or not the overcurrent protection operation is repeated based on the input signal from the output terminal QN of the latch circuit 6. It does not matter how the control circuit 16 determines whether or not the first protection circuit 21a is in a state of repeating the overcurrent protection operation. The control circuit 16 determines, for example, that the overcurrent protection operation is repeated when the number of times the overcurrent protection operation is executed reaches a threshold value in a predetermined fixed period. Although the determination is made based on the input signal from the latch circuit 6, the control circuit 16 makes the above determination based on the signal output by the overcurrent detection circuit 5, the signal output by the current detection unit 3, and the like. You may do it.

When the first protection circuit 21a repeats the overcurrent protection operation (step S5: Yes), the control circuit 16 abnormally stops the first protection circuit 21a (step S6). Specifically, the control circuit 16 controls the switch 73 to maintain the off state to stop the operation of the first protection circuit 21a.

When the first protection circuit 21a does not repeat the overcurrent protection operation (step S5: No), the control circuit 16 drives the switch 73 of the holding circuit 7a to release the state of the latch circuit 6 (step S7). .. Specifically, the control circuit 16 turns on the switch 73 so that the latch circuit 6 is reset by the action of the RC circuit 71 as in the first embodiment. As a result, the state of the output terminal Q of the latch circuit 6 returns to the state before detecting the overcurrent state, and the motor 1 can be re-driven.

Although the operation of the first protection circuit 21a has been described, in the case of the operation of the second protection circuit 22a, in the above step S4, the buffer circuit 13 (see FIG. 1) is transferred from the gate signal generation unit 14 to the gate drive circuit 15 The drive signal input to is cut off.

It should be noted that each of the first protection circuit 21a and the second protection circuit 22a does not include a control circuit for controlling the switch in the holding circuit, but each of the first protection circuit 21a and the second protection circuit 22a. The configuration may include a single control circuit that controls the switches in the holding circuit.

As described above, the motor drive control device 100a according to the present embodiment determines whether each of the first protection circuit 21a and the second protection circuit 22a is in a malfunctioning state in which the overcurrent protection operation is repeated, and operates. In the case of a defective state, the motor 1 is not redriven. This makes it possible to reduce damage to the motor 1 and the switching element due to repeated overcurrent protection.

The configuration shown in the above-described embodiment shows an example of the content of the present invention, can be combined with another known technique, and is one of the configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

1 motor, 2 inverter circuit, 3,4 current detector, 5,11 overcurrent detection circuit, 6,9 latch circuit, 7,7a,10 holding circuit, 8 gate drive power supply, 12,73 switch, 13 buffer circuit , 14 gate signal generator, 15 gate drive circuit, 16 control circuit, 21 first protection circuit, 22 second protection circuit, 52 comparator, 71 RC circuit, 72 transistor circuit, 100 motor drive control device.

Claims (3)

An inverter circuit composed of switching elements that control the energization of the motor,
A gate drive circuit that drives the switching element based on the drive signal,
A first protection circuit that cuts off the power supply to the gate drive circuit and stops the operation of the inverter circuit when the detected value of the current flowing through the motor exceeds the threshold value.
A second protection circuit that blocks the input of the drive signal to the gate drive circuit when the detection value exceeds the threshold value, and
A motor drive control device comprising. The first protection circuit and the second protection circuit are
A current detector that detects the current flowing through the motor and outputs the detected value,
An overcurrent detection circuit that compares the detected value with the threshold value and outputs the comparison result,
A latch circuit that latches and outputs the overcurrent detection signal when the overcurrent detection circuit outputs an overcurrent detection signal indicating that the detection value is equal to or higher than the threshold value.
A holding circuit that stops the output of the overcurrent detection signal after the latch circuit continues to output the overcurrent detection signal for a certain period of time.
The motor drive control device according to claim 1. The first protection circuit and the second protection circuit are
A control circuit that controls the holding circuit so as not to stop the output of the overcurrent detection signal by the latch circuit when the operation of monitoring the operation of the latch circuit and stopping the operation of the inverter circuit is repeated.
The motor drive control device according to claim 2.

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