JP6776901B2 - Electromagnetic brake control method and electromagnetic brake control device - Google Patents

Description

The present invention relates to an electromagnetic brake control method and an electromagnetic brake control device for controlling braking of a rotating electric machine such as an electric motor.

Examples of the conventional electromagnetic brake control method and electromagnetic brake control device include the excitation control circuit of the non-excitation operation brake disclosed in Patent Document 1. The excitation control circuit of the non-excitation operation brake disclosed in Patent Document 1 includes a current detecting means for detecting the energizing current of the motor, a light emitting means for forming a light emitting signal according to the output of the current detecting means, and a light emitting means. A light receiving means for receiving the light emitting signal of the above is provided. Further, the excitation control circuit of the non-excitation operation brake is provided with a brake energization circuit. The brake energizing circuit has a switching element, and when the light receiving means receives a light emitting signal, the switching element is turned on to supply a brake release current to the non-excited operation brake. The excitation control circuit of the non-excitation operation brake disclosed in Patent Document 1 activates the non-excitation operation brake attached to the motor when the power is turned off when the power of the AC motor is turned on / off by an electromagnetic contactor, and the power is turned on. Occasionally releases the non-excited operating brake.

Japanese Unexamined Patent Publication No. 2004-229388

However, in the excitation control circuit of the non-excitation actuated brake disclosed in Patent Document 1, the brake release current supplied to the non-excitation actuation brake depends on the energizing current of the motor. Therefore, for example, when the energizing current of the motor is turned off, there is a problem that the brake release current immediately drops and the brake operates. In addition, the brake release current is choppered and supplied by the field effect transistor (FET) according to the frequency of the energizing current of the three-phase AC motor, so the amount of brake release current depends on the characteristics of the current transformer and photocoupler. Is regulated. Therefore, if the brake release current is insufficient, the non-excited operation brake may not be released.

The present invention has been made in view of the above problems, and an object of the present invention is that it does not depend on the energizing current of the motor, and it is possible to protect the relay that turns the brake current on and off and save power. The present invention provides an electromagnetic brake control method and an electromagnetic brake control device.

In order to solve the above problems, the present invention provides an electromagnetic brake that brakes a rotating electric machine, a brake current circuit that supplies a brake current from a power source to the electromagnetic brake, and energization and interruption of a brake current in the brake current circuit. The relay is provided with a relay for switching, a protection circuit for protecting the relay from a surge voltage, a current control means for controlling the brake current, and a controller for controlling the relay and the current control means. In the electromagnetic brake control method in which the operation of the electromagnetic brake is released and the electromagnetic brake is operated by shutting off the brake current, the energization of the brake current is started when the brake switch connected to the controller is turned on. The brake current is increased from the start of energization of the brake current to release the operation of the electromagnetic brake, and after the brake current reaches a preset target current value or a preset set time from the start of energization of the brake current. after elapsed, the brake current is lowered to a preset setting current value to allow continued release of actuation of the electromagnetic brake, Chi coercive the brake current to the set current value, the controller, the brake current It is characterized in that the interruption of the brake current by the relay is prohibited from the start of energization until the current value drops to the set current value .

In the present invention, the brake current is energized and the operation of the electromagnetic brake is released when the brake current rises. After the current value reaches the target current value after the operation of the electromagnetic brake is released, or after a preset set time elapses from the start of energization of the brake current, the brake current is reduced to the preset set current value, and the set current is set. It is kept at the value. The set current value is a current value at which the operation of the electromagnetic brake can be continuously released. Since the set current value is lower than the target current value or the maximum current value at the set time, even if the energization of the brake current is cut off for the operation of the electromagnetic brake from the state where the set current value is maintained, the surge The voltage is suppressed, making it easier to protect the relay and preventing heat generation in the protection circuit. Moreover, it does not depend on the energizing current of the motor. Moreover, since the set current value is low, power saving is realized.

Further, when the current value higher than braking current set current value, because it can not shut off the brake current, it is possible to reliably protect the relay.

Further, the electromagnetic brake control process mentioned above, the controller, after the lapse of the set time, may be reduced to the set current value set the brake current advance.
In this case, since the brake current rises to the current value at which the operation of the electromagnetic brake is released by the elapse of the set time, the operation of the electromagnetic brake can be reliably released without detecting the current value.

Further, the electromagnetic brake control process mentioned above, the controller may start the energization of the braking current by ON signal and an ON signal of the accelerator sensor of the brake switch.
In this case, since the release of the operation of the electromagnetic brake requires not only the on signal of the brake switch but also the on signal of the accelerator sensor, for example, the operation of the electromagnetic brake is not released only by depressing the brake pedal.

Further, the present invention includes an electromagnetic brake that brakes a rotary electric machine, a brake current circuit that supplies a brake current from a power source to the electromagnetic brake, a relay that switches between energization and interruption of the brake current in the brake current circuit, and the relay. A protection circuit for protecting from a surge voltage, a current control means for controlling the brake current, and a controller for controlling the relay and the current control means are provided, and the operation of the electromagnetic brake is released by energizing the brake current. In an electromagnetic brake control device that operates the electromagnetic brake by shutting off the brake current, the controller starts energizing the brake current when the brake switch connected to the controller is turned on, and the brake current of the brake current After the brake current is increased from the start of energization to release the operation of the electromagnetic brake and the brake current reaches a preset target current value, or after a preset set time has elapsed from the start of energization of the brake current. the brake current is lowered to a preset setting current value to allow continued release of actuation of the electromagnetic brake, Chi coercive the brake current to the set current value, the set current value from the energization start of the braking current It is characterized in that the interruption of the brake current by the relay is prohibited until the current decreases to.

According to the present invention, it is possible to provide an electromagnetic brake control method and an electromagnetic brake control device that do not depend on the energizing current of the motor, protect the relay that turns the brake current on and off, and save power. it can.

It is a block diagram which shows the electric structure of the electromagnetic brake control device which concerns on embodiment of this invention. It is a graph which shows the relationship between the brake current and time of the electromagnetic brake control device which concerns on embodiment of this invention. It is a block diagram which shows the electric structure of the electromagnetic brake control device which concerns on another example.

Hereinafter, the electromagnetic brake control device and the electromagnetic brake control method according to the embodiment of the present invention will be described with reference to the drawings. The electromagnetic brake control device of this embodiment is an example applied to an electric forklift as an industrial vehicle. In particular, this is an example of an electromagnetic brake control device and an electromagnetic brake control method applied to a reach forklift in which the operation of the electromagnetic brake is released by depressing the brake pedal.

The electrical configuration of the electromagnetic brake control device 10 shown in FIG. 1 will be described. The electromagnetic brake control device 10 includes an electromagnetic brake 12 that brakes an electric motor 11 as a rotary electric machine. The electromagnetic brake 12 is mechanically connected to the electric motor 11. The electric motor 11 is braked when the electromagnetic brake 12 is operating (brake on), and the electric motor 11 can be driven when the electromagnetic brake 12 is not activated (brake off). Although not shown, the electromagnetic brake 12 has a solenoid which is a coil component.

The electromagnetic brake 12 is connected to the battery 14 as a power source by the brake current circuit 13. The battery 14 supplies the brake current to the electromagnetic brake 12 via the brake current circuit 13. The battery 14 is a secondary battery that can store DC power and can be charged and discharged. In the brake current circuit 13, the diode 15 is connected in parallel with the electromagnetic brake 12. The diode 15 is a flywheel diode that absorbs the electromagnetic energy stored in the solenoid, which is a coil component of the electromagnetic brake 12, by energizing the brake current. The brake current is the current applied from the battery 14 to the electromagnetic brake 12.

The brake current circuit 13 includes a first switching element 16 as a relay for switching between energization and interruption of the brake current in the brake current circuit 13. The first switching element 16 is a semiconductor relay, specifically, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). The on / off switching operation of the first switching element 16 switches the energization and interruption of the brake current in the brake current circuit 13. The first switching element 16 is connected to the controller 17, and the controller 17 outputs a drive voltage for causing the first switching element to perform on / off switching operation to the gate terminal of the first switching element 16. When the brake current is applied to the electromagnetic brake 12, the electromagnetic brake 12 is released and the braking of the electric motor 11 is released. When the brake current is cut off, the electromagnetic brake 12 is operated and the electric motor 11 is braked.

The protection circuit 18 is connected in parallel with the first switching element 16. The protection circuit 18 is a circuit for protecting the first switching element 16 from a surge voltage generated during a switching operation by the first switching element 16. Specifically, a Zener diode or a varistor is used in the protection circuit 18.

The brake current circuit 13 includes a second switching element 19 as a current control means. The second switching element 19 is connected to the controller 17 and duty-controls the brake current that energizes the electromagnetic brake 12. Specifically, the second switching element 19 performs an on / off switching operation based on the PWM signal output from the controller 17 to the gate terminal of the second switching element 19. The duty ratio in the on / off switching operation of energization of the brake current is the on time ratio. The controller 17 determines the duty ratio so that the brake current applied to the electromagnetic brake 12 becomes a required current value.

By the way, the controller 17 is connected to a brake pedal switch 20 provided on a brake pedal (not shown). The brake pedal is provided on the floor of the driver's seat of the forklift. The on / off signals of the brake pedal switch 20 are transmitted to the controller 17. When the brake pedal is depressed and the on signal from the brake pedal switch 20 is transmitted to the controller 17, the controller 17 controls the first switching element 16 and the second switching element 19, and energizes the electromagnetic brake 12 with the brake current. .. The electromagnetic brake 12 is released by energizing the electromagnetic brake 12 with a brake current. The controller 17 determines the duty ratio required to obtain the brake current required to release the operation of the electromagnetic brake 12, and the second switching element 19 controls the current value of the brake current by duty control based on the PWM signal.

On the contrary, when the depressing of the brake pedal is released and the off signal from the brake pedal switch 20 is transmitted to the controller 17, the controller 17 controls the first switching element 16 to energize the electromagnetic brake 12 with the brake current. Cut off. By interrupting the energization of the brake current to the electromagnetic brake 12, the electromagnetic brake 12 is operated to brake the electric motor 11.

The controller 17 is connected to an accelerator sensor 21 provided on an accelerator lever (not shown). The accelerator lever is provided in the driver's seat of the forklift. The accelerator sensor 21 transmits a signal to the controller 17 according to the amount of operation of the accelerator lever. When the position of the accelerator lever is operated to the position where the forklift is moved forward (hereinafter, "forward position") and the position where the forklift is moved backward (hereinafter, "reverse position"), a signal corresponding to the amount of operation is transmitted. No signal is emitted when the accelerator lever is in the neutral position.

In the present embodiment, the controller 17 is set to apply the brake current to the electromagnetic brake 12 when the brake pedal is depressed and the accelerator lever is operated to the forward position or the reverse position. Therefore, the brake current is not applied to the electromagnetic brake 12 simply by depressing the brake pedal without operating the accelerator lever so as to move forward or backward. Also, simply returning the accelerator lever to the neutral position does not cut off the energization of the brake current, but the energization of the brake current is cut off when the accelerator lever is in the neutral position and the brake pedal is released. Is set to.

Next, the electromagnetic brake control method according to the present embodiment will be described. The forklift is in a stopped state in advance. When the operator gets on board, depresses the brake pedal, and operates the accelerator lever to the forward position, the brake pedal switch 20 connected to the controller 17 is turned on, and the signal of the accelerator sensor 21 according to the operation amount of the accelerator lever is sent to the controller 17. Is transmitted to.

When the ON signal of the brake pedal switch 20 and the signal of the accelerator sensor 21 are transmitted to the controller 17, the controller 17 controls the first switching element 16 to start energizing the brake current, and the second switching is performed by the PWM signal. The element 19 is controlled. The second switching element 19 raises the brake current that energizes the electromagnetic brake 12 from the energization start T0 by duty control based on the PWM signal. As shown in FIG. 2, when the brake current increases from the start of energization of the brake current T0 to the time T1, the operation of the electromagnetic brake 12 exceeds the current value IA in which the operation of the electromagnetic brake 12 is released in the process of increasing the brake current, and the electromagnetic brake 12 operates. Is released. When the operation of the electromagnetic brake 12 is released, the forklift starts traveling at a speed corresponding to the amount of operation of the accelerator lever. At time T1, the brake current reaches a preset target current value I1.

After the brake current reaches the preset target current value I1, the brake current does not increase or decrease and the target current value I1 is maintained until the time T2. The time from the start of energization T0 to the time T2 is preset and stored in the controller 17 as the set time P0. Therefore, when the set time P0 elapses and the time T2 is reached, the brake current starts to decrease according to the command of the controller 17, and decreases until the time T3 is reached. When the time T3 is reached, the brake current drops to the current value I2, but the current value I2 is higher than the lower limit current value IB that enables the release of the operation of the electromagnetic brake 12 to be continued. Therefore, the release of the electromagnetic brake 12 is maintained. After the time T3, the brake current is kept at the current value I2. The current value I2 corresponds to a preset current value that enables the release of the operation of the electromagnetic brake 12 to be continued. The lower limit current value IB that continues to be released after the operation of the electromagnetic brake 12 is released is smaller than the current value IA that releases the operation of the electromagnetic brake 12. If the current value I2 is higher than the current value IB, it may be lower than the current value IA. Incidentally, in the present embodiment, the set current value I2 is about 1/3 of the target current value I1.

In FIG. 2, a period P1 from the start of energization T0 to the time T3 and a period P2 after the time T3 are set. The period P1 can be set in 1 second to several seconds, although it depends on the specifications of the electromagnetic brake 12, and is set to about 1 second in this embodiment. The period P2 fluctuates depending on whether or not the accelerator lever or the brake pedal is operated, and continues as long as the brake pedal is depressed. The period P1 is stored in advance in the controller 17. The controller 17 prohibits the first switching element 16 from interrupting the brake current during the period P1 between the start of energization of the brake current T0 and the decrease to the current value I2, and the first switching element 16 during the period P2. Allow the interruption of the brake current. Therefore, since the electromagnetic brake 12 is continuously released during the period P1, the electric motor 11 cannot be braked.

The brake current in the period P1 is almost higher than the current value I2, which is the set current value. Incidentally, if the brake current is cut off in a state where the brake current is a high current value, excessive heat generation may occur in the first switching element 16, the controller 17, and the protection circuit 18. Therefore, the controller 17 is set to prohibit the interruption of the brake current during the period P1 and allow the interruption of the brake current during the period P2. The period P1 is the timing of starting the running from the stopped state of the forklift, and there is almost no need to operate the electromagnetic brake 12 at a low speed immediately after the start of running. Since the period P1 is about 1 second, it is considered sufficient to cut off the brake current in the period P2 immediately after the elapse of the period P1. Furthermore, when braking of the electric motor 11 is required during the period P1, it is possible to utilize the braking force due to the regeneration of the electric motor 11.

According to the electromagnetic brake control device 10 and the electromagnetic brake control method of the present embodiment, the following effects are obtained.
(1) The brake current is energized, and the operation of the electromagnetic brake 12 is released when the brake current rises. After the operation of the electromagnetic brake 12 is released and the preset time P0 elapses, the brake current is reduced to the preset set current value I2 and maintained at the preset current value I2. The set current value I2 is a current value at which the operation of the electromagnetic brake 12 can be continuously released. The set current value I2 is lower than the target current value I1. From this, even if the current of the brake current is cut off for the operation of the electromagnetic brake 12 from the state where the set current value I2 is maintained, the surge voltage is suppressed and the first switching element 16 is protected from excessive heating. In addition to being easy, it is possible to prevent heat generation in the protection circuit 18. Further, the brake current does not depend on the energizing current of the electric motor 11. Further, since the set current value I2 is about 1/3 of the target current value I1, power saving is realized.

(2) The controller 17 prohibits the first switching element 16 from interrupting the brake current from the start of energization of the brake current T0 to the decrease to the set current value I2. Therefore, when the brake current is a current value higher than the set current value I2, the brake current cannot be cut off, so that the first switching element 16 can be reliably protected.

(3) The controller 17 reduces the brake current to a preset set current value I2 after the lapse of the set time P0. Since the brake current rises to the current value IA that releases the operation of the electromagnetic brake 12 by the time from the start of energization T0 to the time T2, the operation of the electromagnetic brake 12 is performed without detecting and confirming the current value. It can be released with certainty.

(4) The controller 17 starts energizing the brake current by the ON signal of the brake pedal switch 20 and the ON signal of the accelerator sensor 21. Therefore, the release of the operation of the electromagnetic brake 12 requires not only the on signal of the brake pedal switch 20 but also the on signal of the accelerator sensor 21, so that the operation of the electromagnetic brake 12 is released by simply stepping on the brake pedal, for example. Will not be done.

(5) The brake current energized to the electromagnetic brake 12 does not depend on the motor current energized to the electric motor 11. Therefore, the electromagnetic brake 12 does not brake the electric motor 11 due to the decrease in the motor current, and an unintended sudden stop due to the decrease in the motor current can be prevented.

The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the gist of the invention. For example, the present invention may be modified as follows.

○ In the above embodiment, a switching element (MOSFET) which is a semiconductor relay is used as the relay, but the relay is not limited to the semiconductor relay. For example, as in the modified example shown in FIG. 3, a mechanical relay 31 may be used. In this case, a switch circuit 32 that controls the opening and closing of the contacts of the relay 31 may be provided. The controller 17 controls the switch circuit 32 based on the signal of the brake switch and the signal of the accelerator sensor. As a result, the same effect as in the case of the embodiment using the semiconductor relay is obtained. When a semiconductor relay is used, an IGBT (Insulated Gate Bipolar Transistor) may be used as the relay instead of the MOSFET.
○ In the above embodiment, the controller sets the brake current in advance so that the operation of the electromagnetic brake can be continuously released after the preset time (time P0 from the start of energization T0 to the time T2) has elapsed. It was said that the current value would be reduced, but this is not the case. For example, the target current value of the brake current is set, and after the brake current reaches the preset target current value, the brake current is reduced to the preset current value that enables the release of the electromagnetic brake operation to be continued. You may let me.
○ In the above embodiment, the controller starts energizing the brake current by the on signal of the brake switch and the on signal of the accelerator sensor, but this is not the case. The controller may start energizing the brake current by, for example, an ON signal of the brake switch.
○ In the above embodiment, a switching element (MOSFET) is used as the current control means, but an IGBT may be used instead of the MOSFET.

10 Electromagnetic brake control device 11 Electric motor 12 Electromagnetic brake 13 Brake current circuit 14 Battery (power supply)
15 Diode 16 1st switching element (relay)
17 Controller 18 Protection circuit 19 Second switching element (current control means)
20 Brake pedal switch 21 Accelerator sensor 31 Relay (mechanical)
32 Switch circuit T0 Energization start T1, T2, T3 Time I1 Current value (target current value)
I2 current value (set current value)
IA, IB current value P0 period (set time)
P1, P2 period

Claims (4)

An electromagnetic brake that brakes a rotating electric machine and
A brake current circuit that supplies the brake current from the power supply to the electromagnetic brake,
A relay that switches between energization and interruption of the brake current in the brake current circuit,
A protection circuit that protects the relay from surge voltage and
The current control means for controlling the brake current and
A controller for controlling the relay and the current control means is provided.
In an electromagnetic brake control method in which the operation of the electromagnetic brake is released by energizing the brake current and the electromagnetic brake is operated by shutting off the brake current.
When the brake switch connected to the controller is turned on, the energization of the brake current is started.
From the start of energization of the brake current, the brake current is increased to release the operation of the electromagnetic brake.
After the brake current reaches a preset target current value or after a preset set time has elapsed from the start of energization of the brake current.
The brake current is reduced to a preset current value that enables the release of the operation of the electromagnetic brake to be continued.
Chi coercive the brake current to the set current value,
The electromagnetic brake control method, wherein the controller prohibits the relay from interrupting the brake current between the start of energization of the brake current and the decrease to the set current value . It said controller after the predetermined time, the electromagnetic brake control method according to claim 1, wherein the reduced to the set current value set the brake current advance. The electromagnetic brake control method according to claim 1 or 2 , wherein the controller starts energization of the brake current by an on signal of a brake switch and an on signal of an accelerator sensor . An electromagnetic brake that brakes a rotating electric machine and
A brake current circuit that supplies the brake current from the power supply to the electromagnetic brake,
A relay that switches between energization and interruption of the brake current in the brake current circuit,
A protection circuit that protects the relay from surge voltage and
A current control means for controlling the brake current and
A controller for controlling the relay and the current control means is provided.
In an electromagnetic brake control device that releases the operation of the electromagnetic brake by energizing the brake current and operates the electromagnetic brake by shutting off the brake current.
The controller starts energizing the brake current when the brake switch connected to the controller is turned on.
From the start of energization of the brake current, the brake current is increased to release the operation of the electromagnetic brake.
After the brake current reaches a preset target current value or after a preset set time has elapsed from the start of energization of the brake current.
The brake current is reduced to a preset current value that enables the release of the operation of the electromagnetic brake to be continued.
Keeping the brake current at the set current value,
An electromagnetic brake control device characterized in that interruption of the brake current by the relay is prohibited between the start of energization of the brake current and the decrease to the set current value.

Images