JP2017169441A - Motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately determine an abnormality occurrence factor, in a safety circuit that cuts off a PWM signal driving an inverter unit.SOLUTION: A motor control unit (1) includes: an inverter unit (30) converting a direct current to an alternating current; a control unit (10) generating a PWM signal for driving the inverter unit (30) in response to a motor drive command from an external host device; and a safety circuit (20) interposed between the inverter unit (30) and the control unit (10). The inverter unit (30) includes an upper switching element (21) and a lower switching element (23). The safety circuit (20) includes AND circuits (4) which are provided corresponding to the upper switching element (21) and the lower switching element (23), respectively and each of which has two or more inputs to cut off the PWM signal based on a safety input signal.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a motor control device.

  A motor control device including a safety circuit that safely stops a motor based on an input from an emergency stop switch or the like is known (Patent Document 1). In the motor control device of Patent Document 1, a safety circuit (safety stop circuit) is interposed between a PWM circuit that generates a PWM (Pulse Width Modulation) signal that drives a motor and a drive circuit that drives an inverter unit. Yes. The safety circuit is composed of a three-state buffer, and blocks the PWM signal input to the drive circuit by using the input of the motor stop switch as the control input of the three-state buffer.

JP 2010-104187 A

  The motor control device supplies power to the motor using a three-phase power supply line.

  The inverter unit to which the PWM signal is input includes three switching element pairs respectively corresponding to the U phase, V phase, and W phase of the motor. That is, a series circuit comprising a pair of a U-phase upper switching element and a U-phase lower switching element is provided corresponding to the U phase. A series circuit composed of a pair of a V-phase upper switching element and a V-phase lower switching element is provided corresponding to the V phase. Further, a series circuit composed of a pair of a W-phase upper switching element and a W-phase lower switching element is provided corresponding to the W phase. These three series circuits are connected in parallel to the DC power supply. U-phase, V-phase, and W-phase armature windings are respectively connected to these three switching element pairs. When the safety circuit is configured with a 3-state buffer as in Patent Document 1, an abnormal state can be detected for the 3-state buffer itself, but the signal path that configures the safety circuit cannot be monitored.

  One aspect of the present invention has been made in view of the above-described problems, and an object of the present invention is to appropriately grasp the cause of abnormality in a safety circuit that cuts off a PWM signal supplied to an inverter unit. An object is to provide a motor control device.

  In order to solve the above problems, a motor control device according to an aspect of the present invention includes an inverter unit that converts direct current to alternating current, and a motor drive signal that drives the inverter unit from a motor drive command from an external host device. And a motor control device including a safety stop circuit interposed between the inverter unit and the control unit, the inverter unit including an upper switching element and a lower switching element, The safety stop circuit includes logic gates having two or more inputs that block the motor drive signal based on a safety input signal, corresponding to each of the upper switching element and the lower switching element.

  In the motor control device according to the present invention, the control unit may include at least one output signal of each of the logic gates having the two or more inputs and the safety input signal corresponding to the output signal. It is configured to be input, and monitors either one of the safety input signal or the output signal to diagnose a failure of the motor control device.

  In the motor control device of the present invention, the control unit is configured to input at least one output signal of each of the logic gates having the two or more inputs and a safety input signal corresponding to the output signal. The state of the logic gate having the two or more inputs is diagnosed from the output signal and the safety input signal.

  In the motor control device of the present invention, the control unit inputs a self-diagnosis signal to each input terminal of the logic gate having two or more inputs, and outputs a signal input to the input terminal. By monitoring, the signal path corresponding to the logic gate having the two or more inputs is monitored.

  In the motor control device of the present invention, the safety stop circuit receives the motor driving signal and the safety input signal, and the logic gate having the two or more inputs when the safety input signal is Low. The output from becomes low, and the motor drive signal is cut off.

  The present invention has an effect that it is possible to appropriately grasp the cause of abnormality in a safety circuit that cuts off a PWM signal supplied to an inverter unit.

It is a figure which shows the structure of the motor control system in embodiment of this invention. It is a figure which shows the structure of the safety circuit in embodiment of this invention.

  The configuration of the motor control system will be described with reference to FIG. The motor control system 100 includes a motor 40 and a motor control device 1, and the motor control device 1 includes a control unit 10, a safety circuit 20 (safety stop circuit), and an inverter unit 30.

  The control unit 10 includes a motor control unit 11 and a safety control unit 13. The control unit 10 may typically employ a configuration in which a microprocessor reads and executes a software module, or may be configured by a combination of a software module realized by a microprocessor and a dedicated circuit. Moreover, it may be configured by a combination of software modules executed by a plurality of microprocessors.

  The motor control unit 11 outputs a PWM signal (motor drive signal) for driving the motor 40 from a command value (motor drive command) from an external host device and a feedback value from a position sensor (not shown).

  The inverter unit 30 typically includes three switching element pairs corresponding to the U phase, V phase, and W phase of the motor 40. That is, the switching element pair corresponding to the U phase is obtained by connecting the U-phase upper switching element UH (21) and the U-phase lower switching element UL (23) in series. The switching element pair corresponding to the V phase is obtained by connecting the V phase upper switching element VH (21) and the V phase lower switching element VL (23) in series. The switching element pair corresponding to the W phase is obtained by connecting the W phase upper switching element WH (21) and the W phase lower switching element WL (23) in series. These three switching element pairs are connected in parallel to a DC power source (not shown). The armature winding of each phase of the motor 40 is connected between the upper switching element 21 and the lower switching element 23 in each switching element pair. The inverter unit 30 drives the motor 40 by switching between the upper switching element 21 and the lower switching element 23 based on the PWM signal.

  The safety circuit 20 receives the PWM signal for the upper switching element 21 output from the control unit 10, the PWM signal for the lower switching element 23 output from the control unit 10, and the safety input signal. When this happens, the PWM signal supplied to the upper switching element 21 and the lower switching element 23 of the inverter unit 30 is cut off.

  Details of the operation of the safety circuit will be described with reference to FIG.

  The safety circuit 20 includes an AND circuit (logical product circuit) having six N inputs for the upper switching element 21 and the lower switching element 23, respectively. A safety input signal from a safety controller (not shown) or a safety input signal from the safety control unit 13 is input to the safety circuit 20.

  Each of the AND circuits 4 (logic gates) includes an input terminal 41 for a safety input signal “Safety_In” and an input terminal 42 to which a PWM signal is input. When the safety input signal “Safety_In” is High, a PWM signal is output from the AND circuit 4. On the other hand, when the safety input signal “Safety_In” becomes Low, the output (output signal) from the AND circuit 4 becomes Low, and the output of the PWM signal from the AND circuit 4 is cut off.

  As described above, by inputting the safety input signal to the AND circuit 4 for the PWM signal corresponding to the upper switching element 21 and the lower switching element 23, the safety input signal is input to each of the upper switching element 21 and the lower switching element 23. The PWM signal can be cut off based on the safety input signal “Safety_In”.

  Next, monitoring of the output from the AND circuit 4 will be described. An output from the AND circuit 4 is input to the control unit 10. Further, the safety input signal “Safety_In” input to the input terminal 41 is also input to the control unit 10. The control unit 10 monitors the output of the AND circuit 4 and the safety input signal for each of the upper switching element 21 and the lower switching element 23.

  When any of the outputs from the AND circuit 4 is not 0 (Low) when the input of the safety input signal is Low, the control unit 10 determines that the safety circuit 20 is abnormal.

  When the input of the safety input signal is 1 (High), if it is output only from one of the AND circuits 4, that is, if there is an AND circuit 4 to which no PWM signal is output, the control unit 10 determines that the safety circuit 20 is abnormal. When the controller 10 determines that the safety circuit 20 is abnormal, the controller 10 stops outputting the PWM signal.

  As a result, the control unit 10 can monitor “Safety_In” obtained by performing a logical product operation on each of the upper PWM signal and the lower PWM signal and the output from the logical product circuit 4. As a result, the state of the AND circuit 4 can be diagnosed, and the failure of the motor control device 1 can be diagnosed.

  Further, the control unit 10 inputs a self-diagnosis signal to a signal line connected to the input terminal 41 of the AND circuit 4 and monitors a signal input to the input terminal 41 of each AND circuit 4 to thereby provide a signal path. You may monitor for abnormalities. At this time, the self-diagnosis signal is typically composed of a pulse signal having a predetermined length of fall and rise time.

  The control unit 10 can be configured to monitor the logical product circuit 4 configured by six and the signal lines input to the logical product circuit 4. Therefore, it is possible to appropriately grasp which of the AND circuit 4 and the signal line is the cause of the abnormality.

  If an abnormality occurs in the 3-state buffer in Patent Document 1, all of the PWM signals output from the 3-state buffer become abnormal signals, and the motor M may be in an abnormal state.

  On the other hand, the safety circuit 20 of the present embodiment is divided into a circuit corresponding to the upper switching element 21 and a circuit corresponding to the lower switching element 23. Thereby, for example, even if an abnormality occurs in the circuit corresponding to the upper switching element 21 and all the upper PWM signals output from the circuit become abnormal signals, the circuit corresponding to the lower switching element 23 The lower PWM signal that is output may be a normal signal. Therefore, the possibility that all of the PWM signals output from the safety circuit 20 become abnormal signals is reduced, and the possibility that the motor M is in an abnormal state is reduced.

  Further, the safety circuit 20 includes six AND circuits 4 respectively corresponding to the three upper switching elements 21 and the three lower switching elements 23. Thereby, for example, even if an abnormality occurs in a certain AND circuit 4 and the PWM signal output from the AND circuit 4 becomes an abnormal signal, the PWM signal output from another AND circuit 4 May be a normal signal. Therefore, the possibility that all of the PWM signals output from the safety circuit 20 are abnormal signals is further reduced, and the possibility that the motor M is in an abnormal state is further reduced.

(Additional notes)
In the present embodiment, the three-phase motor 40 is used, but a two-phase motor may be used. In this case, the number of PWM signals may be four and the logical product circuit 4 may be four. In this embodiment, a PWM signal is used as a signal for driving the motor 40. However, a signal for changing a current or voltage to the motor 40 may be used.

  In the present embodiment, the logical product circuit 4 is used, but other logical gates such as a negative logical product (NAND) circuit may be used. In this case, the phases of the safety input signal and the PWM signal may be determined appropriately based on the logic gate to be used. Further, in the present embodiment, two signals are input to the AND circuit 4, but three or more signals may be input.

  Further, a drive circuit for driving the upper switching element 21 and the lower switching element 23 of the inverter unit 30 may be provided between the safety circuit 20 and the inverter unit 30 based on the PWM signal from the safety circuit 20. .

  Moreover, you may comprise as follows in another aspect of this invention.

  That is, the motor control device according to the above aspect includes a drive circuit that drives an inverter unit that converts direct current to alternating current, and a control unit that generates a motor drive signal that drives the drive circuit from a motor drive command from an external host device A safety stop circuit interposed between the drive circuit and the control unit, wherein the drive circuit includes an upper switching element and a lower switching element, and the safety stop circuit May be configured to include the upper switching element that cuts off the motor drive signal based on a safety input signal and a logic gate having two or more inputs corresponding to the lower switching element.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Motor control apparatus 4 AND circuit 10 Control part 11 Motor control part 13 Safety control part 20 Safety circuit (safety stop circuit)
21 Upper switching element 23 Lower switching element 30 Inverter section 40 Motor

Claims (5)

An inverter unit that converts direct current into alternating current, a control unit that generates a motor drive signal for driving the inverter unit from a motor drive command from an external host device, and safety that is interposed between the inverter unit and the control unit A motor control device having a stop circuit,
The inverter unit includes an upper switching element and a lower switching element,
The safety stop circuit includes a logic gate having two or more inputs for cutting off the motor drive signal based on a safety input signal, corresponding to each of the upper switching element and the lower switching element. A motor control device.   The control unit is configured to receive at least one output signal of each of the logic gates having the two or more inputs and the safety input signal corresponding to the output signal, and the safety input The motor control device according to claim 1, wherein either one of the signal and the output signal is monitored to diagnose a failure of the motor control device.   The control unit is configured to input at least one output signal of each of the logic gates having the two or more inputs and a safety input signal corresponding to the output signal, and the output signal and the safety input signal 2. The motor control device according to claim 1, wherein the state of the logic gate having two or more inputs is diagnosed.   The control unit inputs a self-diagnosis signal to each input terminal of each of the logic gates having the two or more inputs, and monitors the signals input to the input terminals to thereby detect the two or more The motor control device according to claim 1, wherein a signal path corresponding to a logic gate having an input is monitored.   The safety stop circuit receives the motor drive signal and the safety input signal. When the safety input signal becomes low, the output from the logic gate having two or more inputs becomes low, and the motor drive The motor control device according to claim 1, wherein the signal is cut off.

Images