JP2008271612A - Motor control circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent excessive current from being passed at a quick stop due to dynamic braking with respect to a motor control circuit that controls a motor through an inverter circuit. <P>SOLUTION: The motor control circuit is so constructed that the following is implemented: a motor is driven by supplying the motor with alternating-current voltage through the inverter circuit having switching elements, such as field effect transistors, on the high side and on the low side; and the motor is quickly stopped by simultaneously turning on the switching elements on the high side or low side of the inverter circuit to short-circuit motor terminals to each other. The motor control circuit is provided with a DUTY adjustment circuit that makes it possible to change the cycle or pulse width with which control is carried out to repetitively and simultaneously turn on and off the switching elements on the high side or low side of the inverter circuit. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a motor control circuit for stopping power generation using braking when the motor is rapidly stopped.

  Rotating the motor by supplying electric power, driving the mechanical load, and stopping the power supply to stop the motor rotation. When the power supply is stopped, the motor continues inertial rotation In order to make a quick stop along with the stop of power supply, a mechanical brake or electromagnetic brake is provided to stop the rotation of the motor or the remaining power when the power supply is stopped. In the case of a motor having a power generation capability based on rotational energy, power generation braking or the like is known in which the generated power is consumed by a resistor or the like to stop the rotation of the motor.

  For example, the motor control circuit has a configuration shown in FIG. 4 and shows a configuration when a single-phase motor is driven by an inverter circuit. 30 is a motor (M), 31 is a DC power supply, and 32 is an inverter. Circuit, 33 is a control circuit, 34-1 to 34-4 are gate drive circuits, 35 is an insulation amplifier, 36 is an amplifier, 37 is an error amplifier, 38 is a PWM comparator, 39 is a triangular wave generation circuit, 40 is a frequency divider circuit, R1 is an output current detection resistor, C1 is a capacitor, L1 and L2 are choke coils, Q1 to Q4 are field effect transistors as switching elements, and D1 to D4 are diodes or parasitic diodes. The motor 30 has a configuration that can generate electric power from the remaining rotational energy when power supply is stopped.

  Voltages + Vcc and -Vcc are supplied from the DC power supply 31 to the inverter circuit 32, and the field effect transistors Q1 to Q4 constituting the inverter circuit 32 are controlled from the control circuit 33 via the gate drive circuits 34-1 to 34-4. Then, the field effect transistors Q1 and Q4 and the field effect transistors Q2 and Q3 are alternately turned on and off, and a single-phase AC voltage is supplied to the motor 30 for rotation. The current flowing at that time is detected by a resistor R1, and amplified by an amplifier 36 via an insulation amplifier 35 for insulating the control circuit side from the potential on the drive circuit side of the motor 30 to be a current detection signal. An error with respect to the value input is obtained and input to the PWM comparator 38, and in synchronization with the signal obtained by dividing the clock signal CLK by the frequency dividing circuit 40, the triangular wave signal is input from the triangular wave generating circuit 39 to the PWM comparator 38 for control. A control signal CONT is input to the circuit 33.

  Further, the control circuit 33 switches the field effect transistors Q1 to Q4 of the inverter circuit 32 so as to start or stop supplying power to the motor 30 by inputting an ON signal or OFF signal indicated as ON / OFF. Controls start of operation or stop of switching operation. At the start of the switching operation, the control circuit 33 turns on the field effect transistors Q1, Q4, turns off the field effect transistors Q2, Q3, and turns off the field effect transistor Q1 so that a current corresponding to the command value can be supplied to the motor 30. , Q4 are turned off, and the field effect transistors Q2 and Q3 are turned on to supply a single-phase AC voltage to the motor 30 for rotation. The choke coils L1 and L2 and the capacitor C1 are for removing a switching frequency component included in the output of the inverter circuit 32, and the DC power source 31 is a rectifier circuit for AC voltage from a commercial AC power source. In general, a rectifying structure is used. When an OFF signal is input to the control circuit 33 to stop the motor 30, the control circuit 33 turns on the field effect transistors Q2 and Q4 on the low side at the same time, for example, and shorts the terminals of the motor 30. Then, rapid braking can be performed by performing dynamic braking. At the time of this rapid stop, the high-side field effect transistors Q1 and Q3 can be turned on at the same time to short-circuit the terminals of the motor 30, and power generation braking can be performed. In general, the field effect transistors Q2 and Q4 are turned on simultaneously.

In addition, a three-phase motor is driven by a three-phase inverter circuit, and during an emergency stop, the switching element of the inverter circuit is controlled to turn on and off the switching element corresponding to a single-phase or three-phase winding, and the current is monitored. A direct current braking method has been proposed in which direct current is supplied to a winding to perform dynamic braking (see, for example, Patent Document 1). Moreover, when the direct current rectified by the rectifier circuit is converted into the three-phase alternating current by the three-phase inverter circuit and the three-phase servo motor is driven and the three-phase servo motor is stopped, the operation of the rectifier circuit is stopped, and the rectifier circuit There has also been proposed a control method in which a regenerative resistor is connected between the inverter and the three-phase inverter circuit via a transistor, and the three-phase servo motor is stopped by dynamic braking (see, for example, Patent Document 2). Synchronous motor control for driving braking with a configuration in which a three-phase synchronous motor is driven by a three-phase inverter circuit, and when generated, the generated DC current flowing through a diode in parallel with the switching element of the three-phase inverter circuit flows through a resistor. A circuit has been proposed (see, for example, Patent Document 3). In addition, when stopping a spindle motor that performs high-speed rotation, a quick stop device that combines a mechanically structured brake and power generation braking of the spindle motor has also been proposed (see, for example, Patent Document 4).
Japanese Patent Application Laid-Open No. 5-344471 JP-A-6-315288 JP 2001-204184 A JP 2003-289684 A

  As described above, various configurations of inverter-driven motors are already known, and a configuration using dynamic braking at the time of rapid stop is common. For example, the main part of the control circuit 33 having the configuration shown in FIG. 4 includes AND circuits 41 and 43, OR circuits 42 and 44, dead time generation circuits 45 and 46, an inverter 47, as shown in FIG. , And gate1 to gate4 indicate gate signals input to the gate drive circuits 34-1 to 34-4 corresponding to the field effect transistors Q1 to Q4. Further, the control signal CONT from the PWM comparator 38 in FIG. 4 is input to the dead time generation circuit 45 and the dead time generation circuit 46 through the inverter 47, and the ON / OFF signal is input to the AND circuits 41 and 43. It is input to the inverting input terminals of the OR circuits 42 and 44. The dead time generating circuits 45 and 46 are for giving a dead time when switching on and off so that the field effect transistors Q1 and Q2 and the field effect transistors Q3 and Q4 are not turned on at the same time.

  The ON / OFF signal indicates ON at the H (high) level, and OFF at the L (low) level. When the control signal CONT is at the high level, the gate signals gate1 and gate4 are output. When the field effect transistors Q1 and Q4 are on, the field effect transistors Q2 and Q3 are off, and the control signal CONT is at a low level, the gate signals gate2 and gate3 are output, the field effect transistors Q2 and Q3 are on, and the field effect transistor Q1 , Q4 are turned off, and this operation is alternately performed to supply an AC voltage to the motor 30.

  When the ON / OFF signal is set to the low level, the gate signals gate4 and gate2 from the OR circuits 42 and 44 are output, and the low-side field effect transistors Q2 and Q4 are turned on. As a result, the terminals of the motor 30 are short-circuited via the choke coils L1, L2, and the motor 30 is rapidly stopped by the generation braking. However, immediately before the low-side field effect transistors Q2 and Q4 are turned on at the same time, the motor 30 has the set number of revolutions, and the voltage generated by the rotational energy due to the number of revolutions is relatively high. When the terminals are short-circuited, an excessive current flows, which causes a problem of generation of noise components and a problem of failure of circuit components such as a field effect transistor.

  An object of the present invention is to solve the above-described conventional problems, and it is possible to limit a current during a rapid stop with a simple configuration.

  The motor control circuit of the present invention supplies an AC voltage to the motor via an inverter circuit having switching elements on the high side and the low side to drive the motor, and the switching element on the high side or the low side In a motor control circuit that turns on simultaneously and turns the terminals of the motor into a short-circuited state and rapidly stops, the high-side or low-side switching elements are simultaneously turned on and off repeatedly during the rapid stop of the motor. In this configuration, a DUTY adjustment circuit is provided.

  The DUTY adjustment circuit may be configured to change a cycle or a pulse width for simultaneously controlling on / off of the high-side or low-side switching elements by an external signal.

  The DUTY adjustment circuit may be configured to change a cycle or a pulse width for simultaneously controlling on / off of the high-side or low-side switching elements by a current detection signal that detects a current flowing through the motor. .

  When the drive voltage of the motor is supplied via the inverter circuit, and the supply of the drive voltage is stopped and stopped rapidly, the switching element on the high side or low side of the inverter circuit is simultaneously turned on and off by the DUTY adjustment circuit By doing so, it is possible to suppress the current flowing through the motor as compared with the case where it is continuously turned on, and it is possible to avoid generation of noise, damage to circuit components, and the like.

  The motor control circuit of the present invention supplies AC voltage to a motor via an inverter circuit having switching elements on the high side and low side to drive the motor, and switches the high side or low side of the inverter circuit. In the motor control circuit that turns on the elements at the same time and quickly stops the motor terminals in a short circuit state, the switching elements on the high side or low side of the inverter circuit are simultaneously turned on and off repeatedly when the motor stops rapidly. It has a configuration in which a DUTY adjustment circuit is provided.

  FIG. 1 is an explanatory diagram of a main part of the first embodiment of the present invention, 11 and 12 are OR circuits, 13 and 14 are AND circuits, 15 is an inhibit circuit, 16 and 17 are dead time generation circuits, 18 is an inverter, 19 is a duty adjustment circuit for adjusting the duty, gate1 to gate4 are gate control signals, CONT is a control signal, ON / OFF is an on / off signal, and CLK is a clock signal. As in the conventional example of FIG. The main part of the motor control circuit shown in FIG. Therefore, the gate control signals gate1 to gate4 correspond to signals applied to the gates of the field effect transistors Q1 to Q4 as the switching elements of the inverter circuit via the gate control circuits 34-1 to 34-4 in FIG. To do. Further, the functions of the dead time generating circuits 16 and 17 and the inverter 18 have a configuration in which timing is set so as not to cause a short circuit with respect to the DC power supply, as in the case described with reference to FIG. The DUTY adjustment circuit 19 has, for example, a counter configuration, and can be configured as a frequency dividing circuit configuration that counts the clock signal CLK and outputs a pulse signal every predetermined number of counts. Input to the inhibit circuit 15. This DUTY adjustment circuit 19 is capable of adjusting the duty of the gate control signals gate2 and gate4, and can adjust only the generation period or generation period of the gate control signals gate2 and gate4 and the pulse width (duty) or pulse width. The configuration. This will be described below with reference to FIG.

  When the ON / OFF signal is at a high level, when the control signal CONT is at a high level, the field effect transistors Q1 and Q4 are turned on by the gate control signals gate1 and gate4 from the AND circuit 13 and the OR circuit 11, and the field effect transistor Q2 , Q3 is turned off. When the control signal CONT is at a low level, the field effect transistors Q2 and Q3 are turned on and the field effect transistors Q1 and Q4 are turned off by the gate control signals gate2 and gate3 from the AND circuit 14 and the OR circuit 12, respectively. Thereby, an AC voltage is supplied to the motor 30, and the motor 30 rotates.

  When the ON / OFF signal is set to the low level, the AND circuits 13 and 14 are closed, the output pulse signal of the DUTY adjustment circuit 19 is input from the inhibit circuit 15 to the OR circuits 11 and 12, and the gate signals gate4 and gate2 Thus, the field effect transistors Q2 and Q4 on the low side of the inverter circuit are turned on, and the on state in this case is repeated according to the pulse signal from the DUTY adjustment circuit 19. As a result, the motor 30 is intermittently short-circuited between the terminals by the field effect transistors Q2 and Q4 to be in a state of dynamic braking, and the motor 30 stops rapidly. In that case, since field effect transistors Q2 and Q4 are not continuously turned on, it is possible to avoid an excessive current from flowing during dynamic braking. The DUTY adjusting circuit 19 has a constant cycle and can change the pulse width that determines the ON period, that is, the configuration that allows the duty to be changed, or the period can be changed to change the number of repetitions of the ON period within the unit time. Configuration can be applied. In other words, it is possible to set an optimal power generation braking current depending on the capacity of the motor 30 and the voltage during power generation braking.

  FIG. 2 is an explanatory diagram of a main part of the second embodiment of the present invention, where the same reference numerals as those in FIG. 1 denote the same names, and 20 denotes a DUTY adjustment circuit. The DUTY adjustment circuit 20 can be configured as a counter similarly to the DUTY adjustment circuit 19 in FIG. 1 described above, but is configured such that the frequency division ratio of the clock signal CLK can be changed by an external signal. When rotating the motor 30 with the ON / OFF signal set to high level, the field effect transistors Q1 and Q4 and the field effect transistors Q2 and Q3 are alternately turned on and off by the same function as the configuration shown in FIG. The motor 30 is rotated by supplying an AC voltage. When the motor is stopped by setting the ON / OFF signal to the low level, the gate signals gate2 and gate4 are output according to the output pulse signal of the DUTY adjustment circuit 20, and the field effect transistors Q2 and Q4 are repeatedly turned on and off accordingly. The terminals of the motor 30 are intermittently short-circuited to perform dynamic braking and to stop rapidly. In this case, as in the first embodiment, the terminals of the motor 30 are not continuously short-circuited, so that an excessive current can be avoided. It is also possible to control the period of the pulse signal from the DUTY adjustment circuit 20 to be longer at first and gradually shorter by an external signal, or the pulse width for controlling the ON period is gradually widened with a constant period. It is also possible to perform control. As a result, the current flowing at the start of dynamic braking can be suppressed, and the time during which the short-circuit current flows can be lengthened in accordance with the decrease in the generated voltage accompanying the decrease in the rotational speed, so that rapid stop can be achieved.

  FIG. 3 is an explanatory diagram of a main part of a third embodiment of the present invention. The same reference numerals as those in FIGS. 1 and 2 indicate the same name, 21 indicates a DUTY adjustment circuit, and 22 indicates an A / D converter. The DUTY adjustment circuit 21 divides the clock signal CLK and outputs a pulse signal. The DUTY adjustment circuit 21 detects a current detection signal (detected by the resistor R1 in FIG. Detection signal) is converted into a digital signal by the A / D converter 22 and used as a frequency division ratio control signal of the DUTY adjustment circuit 21. In this case, the larger the value of the current detection signal, the smaller the duty indicating the ON period by the output pulse signal of the DUTY adjustment circuit 21. Alternatively, the cycle of the on period is lengthened.

  When the motor 30 is rotated with the ON / OFF signal at a high level, the field effect transistors Q1 and Q4 and the field effect transistors Q2 and Q3 are alternately turned on by the same function as the configuration shown in FIGS. The motor 30 is turned off and an AC voltage is supplied to the motor 30 for rotation. When stopping the motor by setting the ON / OFF signal to a low level, the gate signals gate2 and gate4 are output according to the output pulse signal of the DUTY adjustment circuit 21, and the field effect transistors Q2 and Q4 on the low side of the inverter circuit are accordingly turned on. , Repeatedly turning off, the terminals of the motor 30 are intermittently short-circuited, and dynamic braking is performed, thereby rapidly stopping. By detecting the current flowing during this dynamic braking and controlling the DUTY adjustment circuit 21, the on-period is shortened or the on-period is lengthened so that an excessive initial current does not flow, and the detected current value decreases. The on-period can be automatically controlled so as to lengthen the on-period or shorten the on-period.

  Each of the above-described embodiments shows a case in which the low-side field effect transistors Q2 and Q4 of the inverter circuit are simultaneously turned on to short-circuit the terminals of the single-phase motor 30 during a rapid stop. It is also possible to turn on Q1 and Q3 at the same time and short-circuit the terminals of the single-phase motor 30 to perform dynamic braking. It can be applied not only to single-phase motors but also to multi-phase motors such as three-phase motors. In that case, the inverter circuit has a multi-phase configuration, and at least two transistors on the low side or high side are connected simultaneously. It is turned on, and at least two phases are short-circuited so that power braking is performed, and the cycle of the on-period or the length of the on-period is controlled by a DUTY adjustment circuit or the like, thereby forming an intermittent short-circuit state. Therefore, it is possible to avoid an excessive short-circuit current flowing at the time of rapid stop and to enable rapid stop.

It is principal part explanatory drawing of Example 1 of this invention. It is principal part explanatory drawing of Example 2 of this invention. It is principal part explanatory drawing of Example 3 of this invention. It is explanatory drawing of a motor control circuit. It is principal part explanatory drawing of a prior art example.

Explanation of symbols

11, 12 OR circuit 13, 14 AND circuit 15 Inhibit circuit 16, 17 Dead time generation circuit 18 Inverter 19, 20, 21 DUTY adjustment circuit 22 A / D converter

Claims (3)

An AC voltage is supplied to the motor through an inverter circuit having switching elements on the high side and the low side to drive the motor, and the switching element on the high side or the low side is turned on at the same time. In the motor control circuit that quickly stops between the short circuit,
A motor control circuit comprising: a DUTY adjustment circuit that repeatedly performs ON / OFF control simultaneously on the high-side or low-side switching elements at the time of rapid stop of the motor.   2. The motor according to claim 1, wherein the DUTY adjustment circuit has a configuration in which a cycle or a pulse width for simultaneously controlling on and off of the high-side or low-side switching elements can be changed by an external signal. Control circuit.   The DUTY adjustment circuit is configured to change a cycle or a pulse width for simultaneously controlling on / off of the high-side or low-side switching elements according to a current detection signal that detects a current flowing through the motor. The motor control circuit according to claim 1.

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