JPH07143664A - Motor controller - Google Patents

Abstract

PURPOSE:To provide a motor controller equipped with a constraining and protecting function which can accurately protect a motor in a constraining state. CONSTITUTION:A motor controller is equipped with a timer signal generating circuit 3 which outputs a timer signal Vt during first time whenever a start commanding signal is inputted, retriggerable multivibrator M2 which outputs a rotation detecting signal Vn at a prescribed level only during second time which is shorter than the first time, and control signal generating circuit 6 which generates control signals in accordance with the timer signal and rotating detecting signal. The supply of a driving current to a motor is permitted when either the timer signal Vt or rotation detecting signal Vn is generated and inhibited when both signals Vt and Vn disappear.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control having a protection function for preventing damage to the coils of the motor and the components of the drive circuit when the motor is mechanically restrained by a heavy load or the like. It relates to the device.

[0002]

2. Description of the Related Art When an electric motor which is driven by a drive current through a predetermined drive circuit and is rotating is stopped due to a heavy load or the like, an excessive current flows through an armature coil. The child coil may be burnt out, or a component of the drive circuit (for example, a switching element) may be damaged. In order to prevent such a situation from occurring, conventionally, a fuse is inserted in a drive circuit of an electric motor, and the fuse is melted when the electric motor is in a restrained state and an excessive current flows. The supply of the drive current to the motor is stopped to protect the electric motor and the drive circuit.

[0003]

When a fuse is used to protect an electric motor as in the prior art, if the fuse capacity is not properly set, the fuse will be allowed even in an overload state that is allowed for a certain period of time. There is a problem that it is difficult to set the capacity of the fuse because the electric motor stops due to melting.

Further, even if the electric motor is restrained, it may be allowed to continue supplying the drive current for a short time. Therefore, the electric motor can be driven only when the restraint time exceeds a predetermined length. However, it is not possible to manage the restraint time when a fuse is used, so there is the problem that the motor will stop even if the restraint state continues for a short time. It was In this case, although it may be possible to set the capacity of the fuse large, if the capacity of the fuse is set large, it may not be possible to properly protect the electric motor and its drive circuit.

Further, when a fuse is used, it is necessary to replace it when it is blown, so that maintenance is inevitable.

An object of the present invention is to provide an electric motor control device having a restraint protection function capable of appropriately protecting the electric motor in a restrained state without using a fuse.

[0007]

A motor control device according to the present invention has a control terminal to which a control signal having a first level and a second level is inputted, and a control signal of the first level is supplied. A motor drive that controls the drive circuit of the motor so as to allow the drive current to be supplied to the motor when being supplied and to prohibit the supply of the drive current when the second level control signal is supplied. A control circuit, a timer signal generation circuit that is triggered each time a start command signal that commands the rotation of the electric motor is input, and that outputs a timer signal for a first time period, in response to an increase in the rotation speed of the electric motor. A rotation detection pulse generator for generating a rotation detection pulse having a short generation cycle, and a rotation detection of a predetermined level for a second time shorter than the first time when triggered. Signal is output, and the first level when either the timer signal or the rotation detection signal is generated and the retriggerable multivibrator that is triggered each time the rotation detection pulse is given And a control signal generating circuit for generating a control signal of the second level when both the timer signal and the rotation detection signal disappear. The length of the second time is set to be equal to or longer than the generation cycle of the rotation detection pulse Vp when the rotation speed of the electric motor reaches the set value.

In the present invention, a clear signal is also applied to the clear terminal of the multivibrator in order to prohibit the retriggerable multivibrator from generating a rotation detection signal when both the timer signal and the rotation detection signal disappear. It is preferable to provide a circuit for providing.

[0009]

In the above electric motor control device, when the rotational speed of the electric motor reaches the set value while the timer signal is generated after the start-up, and when the electric motor is rotating at the rotational speed equal to or higher than the set value, Since the control signal is at the first level, the motor drive control circuit allows the drive current to be applied to the motor. Therefore, the electric motor rotates without any trouble.

If the rotation speed of the electric motor cannot exceed the set value while the timer signal is generated and the electric motor is restrained by a heavy load or the like, the control signal becomes the second level. The supply of drive current to the electric motor is stopped, and the electric motor and its drive circuit are protected.

With the above arrangement, the restraint time for performing the protection operation can be managed by adjusting the time width of the timer signal, so that the electric motor and its drive circuit can be properly protected in the restraint state. Can be planned.

Further, if a circuit for giving a clear signal to the clear terminal of the retriggerable multivibrator is provided when both the timer signal and the rotation detection signal disappear, when it is detected that the electric motor is in a restrained state. In addition, since the control signal can be held at the second level, the chattering phenomenon that the control signal becomes the first level or the second level occurs, and the motor shows unstable behavior. Can be prevented.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention, in which reference numeral 1 designates a control terminal CTR to which a control signal Vc which is a binary signal having a first level and a second level is inputted. A motor drive control circuit 2 having a terminal to which the rotation command signal Vs is input is a motor drive circuit controlled by the motor drive control circuit 1. The electric motor drive control circuit 1 applies a drive current to the electric motor when the first level control signal is applied, and prohibits the supply of the drive current to the electric motor when the second control signal is applied. Then, the motor drive circuit 2 is controlled.
In the present embodiment, the control signal has two levels, a high level and a low level, and the high level and the low level are the first level and the second level, respectively. Hereinafter, the high level of a binary signal is called the H level, and the low level is the L level.
I will call it a level.

In this embodiment, the electric motor is a three-phase brushless DC electric motor. When the electric motor is a three-phase brushless DC electric motor, the electric motor drive circuit 2 is, for example, a known inverter circuit in which six switch elements such as FETs are connected in a three-phase bridge, and the electric motor drive control circuit 1
Switches the excitation phase of the electric motor according to the position of the magnetic pole of the rotor detected by the position sensor when the H-level rotation command signal Vs is provided and the H-level control signal Vc is provided. , Control signals eu and e for controlling on / off of each switch element of the drive circuit 2
Generate v, ew, ex, ey and ez. As the motor drive control circuit 1, a commercially available integrated circuit (IC) can be used.

Reference numeral 3 denotes a first time T which is triggered each time a rotation command signal for instructing to rotate the electric motor is input.
A timer signal generating circuit for outputting a timer signal during the period of 1. In the present embodiment, this timer signal generating circuit is composed of an IC retriggerable multivibrator M1.
The rotation command signal Vs is applied from the rotation command generation circuit 4 to the trigger input terminal A of the retriggerable multivibrator M1, and the trigger input terminal B is grounded. A power supply voltage Vcc is applied to the Q bar terminal of the retriggerable multivibrator M1 through a resistor R3, and at time t1, a rotation command of H level is issued to the trigger input terminal A of the multivibrator M1 as shown in FIG. 2 (A). When the signal Vs is given, the timer signal Vt (FIG. 2B) which holds the L level for the first time T1 at the Q bar output terminal is obtained. The retriggerable multivibrator M1 is externally provided with a time adjustment resistor R1 and a capacitor C1. By adjusting the time constant determined by the resistor R1 and the capacitor C1, the length of the first time T1 is adjusted. It can be adjusted appropriately. The clear terminal CLR of the retriggerable multivibrator M1 is maintained at the H level state (state in which the multivibrator M1 is not cleared) by being supplied with the voltage Vcc from a power source (not shown).

The rotation command generating circuit 4 is composed of a circuit for outputting a voltage of a constant level through a switch, a CPU constituting a control device for controlling the electric motor, and the like, and FIG.
As shown in (A), a rotation command signal Vs having H level or L level is generated. The rising edge of the signal Vs serves as a start command signal, and the down edge serves as a stop command signal.

Reference numeral 5 denotes a rotation detection pulse generator for generating a rotation detection pulse Vp whose generation cycle becomes shorter as the rotation speed of the electric motor increases as shown in FIG. 2 (D). Is, for example, a photo interrupter type encoder attached to the rotary shaft of the electric motor.

The rotation detection pulse Vp is input to the trigger signal input terminal A of the retriggerable multivibrator M2. The trigger input terminal B of the retriggerable multivibrator M2 is grounded, and the power supply voltage Vcc is applied to the Q-bar output terminal through the resistor R4. This retriggerable multivibrator M2 is triggered every time the H-level rotation detection pulse Vp is applied, and its Q-bar output terminal is driven to L for the second time T2 as shown in FIG. 2 (E).
The rotation detection signal Vn holding the level is output. A resistor R2 and a capacitor C2 are externally attached to the retriggerable multivibrator M2 so that the length of the second time T2 can be adjusted appropriately by adjusting the time constant determined by the resistor R2 and the capacitor C2. It has become.

In the present invention, the second time T2 is the first
Of the rotation detection pulse Vp when the rotation speed of the motor reaches a set value, which is sufficiently shorter than the time T1 of
It is set to be above o (To ≤ T2 << T1). Therefore, as shown in FIG. 2D, when the rotation speed of the electric motor becomes equal to or higher than the set value at time t2, the retriggerable multivibrator is retriggered at intervals shorter than the second time T2. As shown in FIG. 2 (E), the rotation detection signal Vn obtained at the Q-bar output terminal of the retriggerable multivibrator M2 is maintained at L level (it is detected that the electric motor is rotating at a speed higher than the set speed). State)
Becomes

The timer signal Vt and the rotation detection signal Vn are input to the control signal generating circuit 6. The control signal generation circuit 6 includes NAND circuits NAND1 and NAN.
D2, an inverter INV, resistors R5 to R7, and a capacitor C3, and when either the timer signal Vt or the rotation detection signal Vn is generated (V
When one or both of t and Vn are at L level, the control signal Cc of H level is applied to the control terminal CTR of the motor drive control circuit 1, and when both the timer signal Vt and the rotation detection signal Vn disappear (Vt). And V
When both n are at the H level), it is detected that the electric motor is in the restrained state, and the control signal Vc at the L level is given to the control terminal CTR.

The NAND circuit NAND2 of the control signal generation circuit 6 is supplied with the reset signal Vr from the reset signal generation circuit 7. The reset signal Vr is shown in FIG.
As shown in (F), the reset signal V is an L level signal
When r is given, the control signal Vc is unconditionally set to L level to stop the electric motor, and the drive control circuit 1 is returned to the initial state.

In the present embodiment, the NAND circuit NAND1
When the output of is input to the clear input terminal CLR of the retriggerable multivibrator M2 and the output of the NAND circuit NAND1 becomes L level, the output of the Q bar output terminal of the multivibrator M2 unconditionally becomes H level. It is like this.

In the embodiment of FIG. 1, the timer signal Vt, the rotation detection signal Vn, the output signal Va of the NAND circuit NAND1 and the output signal Vb of the NAND circuit NAND2 when the reset signal is not applied (when Vr is at the H level). And output signal (control signal) Vc of the inverter INV
The truth table of is shown in Table 1.

[0024]

[Table 1] Table 2 shows a truth table of Vt, Vn, Va, Vb and Vc when a reset signal is applied (when Vr becomes L level).

[0025]

[Table 2] The operation of the above embodiment will be described below with reference to FIG. Figure 2
As shown in (A), it is assumed that an H level rotation command signal Vs is applied at time t1. This rotation command signal V
s is input to the trigger input terminal A of the retriggerable multivibrator M1 and simultaneously applied to the motor drive control circuit 1. When the rotation command signal Vs becomes H level at time t1, as shown in FIG. 2B, the retriggerable multivibrator M1 holds the timer signal Vt for holding the L level at its Q-bar terminal for the first time T1. To occur. When the L level timer signal Vt is generated, the output Va of the NAND circuit NAND1 becomes H level as shown in FIG. When the output Va of NAND1 becomes H level,
As shown in (G), the output Vb of the NAND circuit NAND2 becomes L level, and as shown in (H) of FIG.
The NV output signal (control signal) Vc becomes H level. Therefore, the electric motor drive control circuit 1 is connected to the electric motor drive circuit 2
Are supplied with control signals eu to ew and ex to ez to start the electric motor.

When the electric motor rotates, the rotation detection pulse generator 5 generates a rotation detection pulse Vp as shown in FIG. 2 (D). When the rotation detection pulse Vp is generated, the retriggerable multivibrator M2 is triggered and the potential of the Q-bar output terminal becomes L level for the second time T2 (the rotation detection signal Vn is generated). When the rotation speed of the electric motor becomes equal to or higher than the set value at the time t2, the multivibrator M2 is retriggered while the rotation detection signal Vn is being generated, so that the output of the Q-bar terminal of the multivibrator M2 is output. Holds the L level, and the rotation detection signal Vn is continuously generated.

At time t3, when the rotation command signal Vs is set to L level and a stop command is given, the motor drive control circuit 1
Stops the supply of drive current to the electric motor, so that the rotation speed of the electric motor decreases. When the rotation speed becomes lower than the set value at time t4, the retriggerable multivibrator M
2 is no longer retriggered, so time t4 (t4-t3
When ≤T2), the output of the Q-bar terminal of the multivibrator M2 becomes H level (the rotation detection signal Vn disappears), and the output Va of the NAND circuit NAND1 becomes L level. Therefore, the output Vb of the NAND circuit NAND2 becomes H level, the output Vc (control signal) of the inverter INV becomes L level, and the motor drive control circuit 1 outputs the control signals eu ...
Stop the output of ew and ex to ez. NAND circuit NA
When the output Va of the ND1 becomes L level, the retriggerable multivibrator M2 is cleared, so that the output of the Q-bar terminal of the multivibrator M2 is unconditionally maintained at H level. Therefore, for example, even if the rotor of the electric motor is rotated by an external force and the rotation detection pulse Vp is generated, the Q-bar output of the multivibrator M2 is held at H level, the rotation detection signal Vn is not generated, and the control signal Vc is H. It never reaches the level.

At time t6, the rotation command signal Vs again becomes H level and a start command is given. At this time, it is assumed that the electric motor cannot be rotated due to the heavy load being restrained. It is also assumed that the rotation detection pulse generator 5 is in a state of continuously generating an H level signal at time t6. This state is, for example, a state in which the light receiving element of the photo interrupter forming the rotation detection pulse generator 5 remains receiving light because the rotor of the electric motor slightly moves only at the moment when the start command is given. .

When the rotation command signal Vs becomes H level at time t6, the multivibrator M1 generates a timer signal Vt. At this time, the retriggerable multivibrator M2 generates the rotation detection signal Vn only during the second time T2, but the motor is not rotating and the rotation detection pulse Vp is generated.
Is not generated (in this example, the trigger input of the multivibrator M2 is kept at H level), so that the output of the Q-bar terminal of the multivibrator M2 is at H level when the second time T2 has elapsed from the time t6. become. While the timer signal Vt is being generated, the NAND circuit NAND
The output Va of 1 becomes H level, and the control signal Vc
Goes to the H level, but the electric motor is in a restrained state, and therefore remains stopped. When the timer signal Vt disappears at time t7, the output signal Va of the NAND circuit NAND1 becomes L.
Since the level is reached (the restrained state of the motor is detected),
The control signal Vc becomes L level, and the motor drive control circuit 1 stops the output of the control signals eu to ew and ex to ez to prohibit the drive current from being applied to the motor. Therefore, by properly setting the time T1 during which the timer signal Va is generated, it is possible to prevent the coil of the electric motor from being burned when the electric motor is in the restrained state, and to protect it by restraining it for a short time. Can be prevented from working.

In the present embodiment, when the restrained state of the electric motor is detected and the output of the NAND circuit NAND1 becomes L level, the multivibrator M2 is cleared and the output of the Q bar terminal of the multivibrator M2 becomes H level. Since the control signal Vc is held at the L level, the motor is not energized even if the rotor of the motor moves and a rotation detection pulse is generated. Therefore, it is possible to prevent the electric motor from exhibiting unstable behavior due to the chattering phenomenon in which the level of the control signal changes when the restrained state is detected.

After removing the cause of restraint of the electric motor, the electric motor is started by applying the H level rotation command signal Vs again.

In the above embodiment, the rotation detection pulse generator 5 continuously generates the H level signal when the restraint state is generated at the time t6. However, the rotation detection pulse generator 5 is restrained in the restraint state. When the output holds L level,
Since the output of the Q-bar terminal of the retriggerable multivibrator M2 maintains the H level, it is possible to detect the restraint state at the time when the first time T1 elapses and perform the protection operation as in the above.

Further, when the electric motor does not maintain a complete stop state in the restrained state but rotates at a rotation speed lower than the set rotation speed, the retriggerable multivibrator M2 passes the first time T1. However, since it is not retriggered, the output of the NAND circuit NAND1 becomes L level when the output of the Q bar terminal of the retriggerable multivibrator M2 becomes H level after the lapse of the first time T1, and the output is in the locked state. Is detected.

In the above embodiment, the timer signal Vt is the L level signal and the rotation detection signal Vn is also the L level signal. However, the levels of these signals depend on the logic circuit configuration of the control signal generating circuit 6. Can be changed appropriately. Further, the levels of the rotation command signal Vs and the control signal Vc can be changed appropriately according to the configuration of the IC.

In the above embodiment, the timer signal generation circuit 3
And a retriggerable multivibrator M1. However, this timer signal generating circuit may be any circuit that generates a timer signal of a certain time width when triggered, and other appropriate monostable multivibrator or other appropriate The timer signal generation circuit 3 can also be configured by a circuit.

[0036]

As described above, according to the present invention, it is possible to manage the restraint time during which the protective operation is performed by adjusting the time width of the timer signal. Therefore, the electric motor in the restraint state and its drive circuit are controlled. There is an advantage that the protection of can be properly achieved.

According to the second aspect of the present invention, a circuit is provided to give a clear signal to the clear terminal of the retriggerable multivibrator when both the timer signal and the rotation detection signal disappear, and the motor is in a restrained state. Since the control signal is held at the second level when it is detected that chattering changes the level of the control signal when a stop command is given or when a restrained state is detected. It is possible to prevent the occurrence of a phenomenon and the unstable behavior of the electric motor.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a waveform diagram showing signal waveforms of respective parts in FIG.

[Explanation of symbols]

 1 motor drive control circuit 2 motor drive circuit 3 timer signal generation circuit 4 rotation command generation circuit 5 rotation detection pulse generator 6 control signal generation circuit M1, M2 retriggerable multivibrator NAND1, NAND2 NAND circuit INV inverter

Claims (2)

[Claims] 1. A control terminal to which a control signal having a first level and a second level is inputted, and a drive current is supplied to the electric motor when the control signal is at the first level. A motor drive control circuit that controls the drive circuit of the motor so as to prohibit the supply of the drive current to the motor when the control signal is at the second level, and a start command signal that commands the rotation of the motor. Timer signal generation circuit that is triggered every time the input is input and outputs a timer signal for the first time, and rotation detection pulse generation that generates a rotation detection pulse whose generation cycle becomes shorter as the rotation speed of the motor increases And a rotation detection pulse that is tuned to output a rotation detection signal of a predetermined level for a second time which is shorter than the first time when triggered. A retriggerable multivibrator that is triggered every time a pulse is given, and that generates the control signal at the first level when either the timer signal or the rotation detection signal is generated, A control signal generating circuit for generating the control signal of the second level when both of the detection signals disappear, the length of the second time is set when the rotation speed of the electric motor reaches a set value. The motor control device that is set to be equal to or longer than the generation cycle of the rotation detection pulse Vp. 2. A circuit for providing a clear signal to a clear terminal of the multivibrator to prohibit the retriggerable multivibrator from generating a rotation detection signal when both the timer signal and the rotation detection signal disappear. The electric motor control device according to claim 1, further comprising: