JPH05219770A - Brake circuit for electric rotating machine - Google Patents

Abstract

PURPOSE:To form a brake circuit without adding any component such as a resistor or a rely, to obtain sufficient damping force even if number of revolutions is reduced and to offer the damping circuit for an electric rotating machine capable of reducing time to be elapsed before stoppage. CONSTITUTION:In a damping circuit for an electric rotating machine electrically braking an electric rotating machine 1 having a field, a first circuit means to increase volume of electric current supplied to an armature winding 3 of the electric rotating machine 1 with time and a second circuit means to decrease volume of electric current supplied to the armature winding 3 of the revolving electric machine 1 with time are provided. A current detection means 8 detecting the current supplied to the armature, a voltage comparator 9 comparing output voltage of the current detection means 8 with a reference voltage and a semiconductor switch group 7 connected alternately with the first circuit means and the second circuit means by output of the voltage comparator 9 to change over are also provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking circuit for a rotary electric machine generally called a dynamic brake.

[0002]

2. Description of the Related Art In rotary electric machines such as motors and generators, a braking circuit called a dynamic brake is used to stop the rotation immediately. In this, electric energy generated by rotation is consumed through a resistor to generate a braking force.

FIG. 11 shows a conventional example of such a braking circuit, which is described in Japanese Patent Application Laid-Open No. 62-181684. In FIG. 11, electric power is supplied from the main circuit power source 32 to each of the armature windings 33 of the motor 31 having the three-phase armature winding 33, and the motor 31 is driven. A variable resistor 34 is connected to each armature winding 33 via a relay switch 35. The other end of each variable resistor 34 is connected to each other. When the brake is applied, the relay switch 35 is closed based on the command, and the terminals of each armature winding 33 are short-circuited with the resistor 34 interposed.
The electric energy generated by the rotation is consumed by the resistor 34, the braking force is generated, and the rotation is stopped.

An example of a circuit for applying a brake while applying a constant brake current is disclosed in Japanese Patent Laid-Open No. 63-16769.
There is one disclosed in Japanese Patent No.

[0005]

According to the above conventional braking circuit, the braking force can be arbitrarily changed by changing the resistance value of the variable resistor 34 according to the motor characteristics. However, in order to effectively apply the braking force, it is necessary to use a large-sized resistor, which requires a large space in proportion to the capacity of the rotating electric machine and causes a cost increase. Further, a large braking force can be obtained while the rotation speed is high, but the braking force decreases as the rotation speed decreases, and there is a problem that it takes a long time to stop. Further, it is necessary to add parts such as a variable resistor and a relay, and there is a problem that reliability is lowered.

The present invention has been made in view of the above problems of the prior art, and makes it possible to configure a braking circuit without adding components such as resistors and relays,
Prevents expansion of space and high cost, is highly reliable, and provides sufficient braking force even when the number of revolutions is reduced, reducing the time required to stop the rotating electrical machine. The purpose is to provide a circuit.

[0007]

In order to achieve the above object, the present invention provides a first circuit means for increasing the magnitude of a current flowing through an armature winding of a rotary electric machine with time, and an armature for the rotary electric machine. Second circuit means for reducing the magnitude of the current flowing through the winding with time, current detecting means for detecting the current flowing through the armature, and a voltage comparator for comparing the output voltage of the current detecting means with a reference voltage. , 1st by the output of the voltage comparator
And a semiconductor switch group for alternately connecting and switching the circuit means and the second circuit means.

[0008]

When the current is applied to the armature winding by the first circuit means, the current increases with time and the output voltage of the current detecting means increases. When the output voltage of the current detecting means becomes higher than the reference voltage of the voltage comparator, the semiconductor switch group switches the circuits so that the second circuit means causes a current to flow through the armature winding. When a current is being applied to the armature winding by the second circuit means, the current decreases with time and the output voltage of the current detecting means drops. When the output voltage of the current detection means becomes lower than the reference voltage of the voltage comparator, the semiconductor switch group switches the circuits so that the first circuit means causes a current to flow through the armature winding. In this way, braking is performed while a substantially constant braking current flows until rotation stops.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a braking circuit for a rotary electric machine according to the present invention will be described below with reference to the drawings. In FIG. 1, the commercial AC power supply 14 is input to the main circuit power supply 2.
The main circuit power supply 2 has a fuse 15, diodes 16, 17, 18, and 19 for full-wave rectifying the commercial AC power input via the fuse 15, and a capacitor C for smoothing the rectified DC. It becomes. Both ends of the capacitor C are connected to a DC power source 20, and the DC power source 20 supplies power to each circuit described later. Here, the rotary electric machine is a DC brushless motor. The DC brushless motor 1 has a field composed of a magnet and also has an armature winding 3 having a three-phase structure. DC power is supplied to each armature winding 3 from the main circuit power supply 2 via the semiconductor switch group 7.

In the power supply path from the main circuit power supply 2 to the semiconductor switch group 7, a current detection resistor 8 is connected as a current detection means for detecting the current flowing in the armature 3. The voltage across the current detection resistor 8 is input to the voltage comparator 9 and compared with the reference voltage in the voltage comparator 9. The output of the voltage comparator 9 switches to a high output voltage level “H” or a low output voltage level “L” depending on whether the voltage across the current detection resistor 8 is higher or lower than the reference voltage,
As a result, the semiconductor switch group 7 is switched via the gate / base drive circuit 6. However, the comparison operation of the voltage comparator 9 is such that when the brake operation signal Vbi is input from the terminal 11, the current detection timing signal 1 having a constant cycle is generated.
It is performed at a constant cycle by 0. As the armature current detecting means, other appropriate current / voltage converting means that can obtain a voltage proportional to the current may be used instead of the resistor 8.

A more specific structure of the above embodiment will be described with reference to FIG. In FIG. 2, the upper three transistors 7a, 7a, 7a and the lower three transistors 7b, 7b, 7b constitute the semiconductor switch group 7. The upper and lower three pairs of transistors 7a and 7b are connected in series, and the respective connection points are connected to one end of each armature winding 3 of the motor 1. The other end of each armature winding 3 is connected together. The upper transistors 7a, 7a, 7a have diodes Da1, D respectively
a2 and Da3 are connected in parallel and in the opposite direction to the respective transistors, and diodes Db1, Db2 and Db3 are also connected in parallel to the lower transistors 7b, 7b and 7b, respectively, and in the opposite direction to the respective transistors. It is connected.

The control command unit 30 is a unit that issues a rotation command and a braking command for the motor 1. As shown in FIG. 5, the driving / braking command signal INVCOM output from the control command unit 30 is a steady driving command “L” and a braking command “H”. The driving / braking command signal INVCOM is input to the gate-base drive circuits 6a of the three upper transistors 7a and the gate-base drive circuits 6b of the three lower transistors 7b. When the driving / braking command signal INVCOM is a steady driving command, the energization signals GD1, GD2, G output from the control command unit 30
D3 controls ON / OFF of the three lower transistors 7b via the respective gate / base drive circuits 6a, and
Energization signals GU1 and GU output from the control command unit 30
2, GU3 controls on / off of the three upper transistors 7a via the respective gate / base drive circuits 6b,
Each armature winding 3 at the timing shown in the left half of FIG.
Is energized to perform normal operation.

The driving / braking command signal INVCOM is "H".
If the command is a braking command at, the energization signal G as shown in FIG.
U1, GU2 and GU3 are invalidated, and the upper three transistors 7a are invalidated. The brake command signal Vbi is output from the control command unit 30. Brake operation signal V
bi becomes “L” after a predetermined short circuit prevention time after the driving / braking command signal INVCOM becomes a braking command,
This starts the braking operation. When the brake operation signal Vbi becomes “L”, the photo coupler 2
No current flows to the output side of 1 and the output of the comparator 9 becomes "H", which is inverted to "L" by the inverter 23. The output of the inverter 23 is used as the GATE signal. This GAT
When the E signal becomes “L”, the three diodes 24, 2
The forward voltage of both terminals of 5, 26 causes a current to flow through these diodes, and the lower three transistors 7b are turned on via the gate-base drive circuits 6b connected to these diodes. Become.

However, the current detection timing signal 10
When the voltage becomes “L” for a short period of time at a constant cycle, the diode 2
2 becomes the forward direction, the output of the comparator 9 becomes "L", and the GATE signal which is the output of the inverter 23 becomes "H". The current detection timing signal 10 is the sampling signal Sam, and this signal 10 is “L” at regular intervals.
Then, the voltage across the current detection resistor 8 and the reference voltage Vref are compared by the comparator 9, and the comparison result is output.

Next, the operation of the above-described embodiment will be described. Since the steady operation operation is the same as that of the conventional DC brushless motor, the braking operation will be described here. In the embodiment shown in FIG. 2, only the portion related to the braking operation is extracted and equivalently shown in FIG. In the example of FIG. 2, the lower three transistors 7b
3 are represented by D1, SW1, D2, SW2, D3, and SW3, respectively, as combinations of diodes and switches in FIG. For the three-phase armature winding 3, the DC resistance component is represented by R and the inductance component is represented by L,
Each induced voltage is represented by Ea, Eb, and Ec.
In the equivalent circuit of FIG. 3, each transistor 7b is turned on,
Therefore, the case where each of the switches SW1, SW2, and SW3 is turned on is set to the a mode, and an equivalent circuit thereof is shown in FIG.
Also, each transistor 7b is turned off, and therefore each switch S
When the W1, SW2, and SW3 are turned off, the b mode is set,
The equivalent circuit is shown in FIG. In FIG. 4, the directions of the armature currents ia (t), ib (t), ic (t) and the induced voltages Ea, Eb, Ec are arbitrarily determined, and it is assumed that the induced voltages are constant. There is.

In the a mode shown in FIG. 4 (a), the armature current ia (t) flowing out of Ea passes through R, L and D1 and is then shunted to Db2 and Db3. The child current ib (t) returns to Ea via L, R, and Eb, and the current shunted to the Db3 side is the armature current ic (t).
Return to Ea via L, R, Ec. In analyzing this equivalent circuit, the forward voltage of each diode is at a level that has no influence, so this is ignored. The following differential equation holds in the a mode.

## EQU00001 ## Ea-Ria (t) -L {dia (t) / dt} =-Eb + Rib (t) + L {dib (t) / dt} =-Ec + Ric (t) + L {dic (t) / dt}

Ia (t) = ib (t) + ic (t) If this is solved for ia (t),

[Equation 3] Becomes Here, S represents a Laplace operator.

In the b mode shown in FIG. 4B, the armature current ia (t) flowing out from Ea is R, L, Da1, C,
After passing through Rc, the current is split into Db2 and Db3, and the current split into Db2 is L, R, Eb as armature current ib (t).
The current shunted to the Db3 side returns to Ea via L, R and Ec as armature current ic (t). Here, in order to simplify the analysis, it is assumed that the voltage Vc across the electrolytic capacitor C of the main circuit power supply is constant. Also,
Since the resistance value of the current detection resistor Rc is very low and the forward voltage of each diode has no influence, these are ignored. In this b mode, the following differential equation holds.

## EQU00004 ## Ea-Vc-Ria (t) -L {dia (t) / dt} =-Eb + Rib (t) + L {dib (t) / dt} =-Ec + Ric (t) +2 {dic (t) / dt}

Ia (t) = ib (t) + ic (t) If this is solved for ia (t),

[Equation 6] Becomes

From Equations 3 and 6, the following can be said. In the a mode, the current ia (t) increases with time. In the b mode, if (2Ea + Eb + Ec) <Vc, the current ia (t) decreases with time. FIG. 6 shows changes in current in the a mode and the b mode. From the above, by turning on and off the three transistors 7b that form the semiconductor switch group to switch between the a mode and the b mode alternately, and controlling the time of the a mode and the b mode, the braking current can be substantially reduced. Can be constant. The above is the basic operation. Although the description has been given here assuming that the directions of the current and the induced voltage are specific directions, the same can be applied to other cases.

Next, the timing of switching between the a mode and the b mode will be described. When the braking operation is started, the three transistors 7b are turned on to be in the a mode, and the current increases. Current detection timing signal Sam at a predetermined cycle
Becomes "L", the transistor 7b is turned off to enter the b mode, and the current irc flows through the current detection resistor Rc.
The current irc decreases with time as shown in FIG. The voltage Vi across the current detection resistor Rc is proportional to the current irc. The voltage comparator 9 detects the voltage V across the current detection resistor Rc.
i is compared with the reference voltage Vref. The output of the voltage comparator 9 is "L" until Vi <Vref, and the transistor 7b remains off. When Vi <Vref, the output of the voltage comparator 9 becomes "H", the transistor 7b is turned on, the current irc = 0, and the voltage comparator 9
Maintains the "H" output.

The above operation is performed by the current detection timing signal Sa
Repeated every m cycles, the braking current is the reference voltage Vref
The value is controlled according to. This reference voltage Vref can be called a braking current command, and if this value can be set arbitrarily, the required braking force can be obtained arbitrarily.

The braking circuit described above is effective when applied to, for example, a circuit of a robot motor. That is, when the fuse 15 shown in FIG. 1 is blown or the commercial alternating-current power supply 14 is cut off and the main circuit power supply 2 is no longer supplied with power, if this is detected and braking is applied, the robot will It is effective for ensuring safety because it stops immediately on the spot and does not move unintentionally. Appropriate means may be selected as the trouble detecting means such as a power failure.

FIG. 7 shows the timing from the detection of trouble to the shift to the braking operation. At the same time when the trouble detection signal is output, the driving / braking command signal INVCOM becomes “H” and the braking command is output. However, as shown in FIG. 5, the brake operation signal Vbi is output after a predetermined short circuit prevention time. Is output, and the braking operation starts from this point. At the time of starting the braking operation, the voltage Vc1 across the electrolytic capacitor C has a value substantially corresponding to the commercial AC power supply voltage, but when shifting to the braking operation, the voltage Vc1 across the electrolytic capacitor C gradually increases. The voltage Vc1 across the capacitor C can be used as a power supply source to drive the DC power supply 20 of the circuit required to maintain the braking operation, so that the normal braking operation is performed even if the commercial AC power supply 14 is not supplied.

According to the embodiment described above, the voltage across the current detection resistor Rc for detecting the armature current is detected, and depending on whether this voltage is higher or lower than the reference voltage Vref,
The first circuit means that operates in a mode, that is, a mode that increases the current flowing in the armature winding with time by turning on and off the transistor that constitutes the semiconductor switch, and the b mode, that is, the current flowing in the armature winding, Since the second circuit means operating in the mode of decreasing with time are alternately switched, the reference voltage Vr
A braking current according to ef can be supplied, and the reference voltage Vr
The braking force can be set arbitrarily by setting ef arbitrarily. Also, the maximum braking current is limited to the smaller of the capacity of the semiconductor switch group or the allowable armature winding current, but the braking current is maintained at the set current until the speed becomes sufficiently low, Effective braking is possible with less rotation due to inertia during an emergency stop or the like.

Further, the current detection resistor Rc, the gate / base drive circuit 6, and the main circuit capacitor C which compose the braking circuit are the circuit components necessary for the steady operation of the motor, and therefore compose the braking circuit. In this case, there is an advantage that it is not necessary to newly add these circuit components and that signal processing can be performed at the logic circuit level, which also has an advantage that the cost is reduced.
Here, the current detection resistor Rc can also be used as an overcurrent detection resistor used for detecting a short circuit of the main circuit and the armature winding.

The present invention is also applicable to a general brush DC motor. An embodiment thereof is shown in FIG. 10 and its equivalent circuit is shown in FIGS. Since this embodiment is basically the same as the above-mentioned embodiment, common components are designated by common reference numerals. In FIG. 8, C is a main circuit electrolytic capacitor, Da1, Da2, Db1 and Db2 are freewheeling diodes, D1 and SW1 are transistors that form a semiconductor switch, D2 and SW2 are transistors that form a semiconductor switch, and R is an armature winding. Resistance, L is the inductance of the armature winding, and Ea is the induced voltage. Also in this embodiment, similarly to the above-mentioned embodiments, the switch S is used for the braking operation.
A mode in which W1 and SW2 are on, and switches SW1 and S
There are two modes of operation, b mode with W2 off.

FIG. 9A shows the a mode, in which L, R, D1, SW1 and Db2 are used with the induced voltage Ea as a power source.
In that order, that is, only in the bridge of the armature winding and the semiconductor switch, the current flows back. FIG. 9B shows the b mode, in which the induced voltage Ea is used as a power source and L, R, Da1, C,
Rc and Db2 flow in this order to charge the capacitor C. Here, since the resistance value of the current detection resistor Rc is very low and the forward voltage of each diode is at a level that does not affect them, these are ignored and each mode is analyzed.

The following differential equation holds for the a mode.

## EQU00007 ## Ea = Ria (t) + L {dia (t) / dt} Solving this

[Equation 8] Becomes S indicates a Laplace operator. The following equation is similarly established for the b mode.

Ea−Vc = Ria (t) + L {dia (t) / dt} If this is solved,

[Equation 10] Becomes

From Equations 8 and 10, the following can be said. a
In the mode, the current ia (t) increases. In the b mode, if Ea <Vc, the current ia (t) decreases.
Therefore, a constant braking current can be flown by alternately turning on and off the semiconductor switch group to switch the connection between the a mode and the b mode, and the on / off timing of the semiconductor switch group can be arbitrarily set. By doing so, the braking current can be set arbitrarily, and the same operational effects as in the case of the DC brushless motor can be obtained.

The present invention can be applied to any rotating electric machine having a field, and can be applied to both a motor and a generator. The type of the motor and the generator is not limited as long as it has a field.

[0030]

According to the present invention, the output voltage of the current detecting means for detecting the armature current is detected, and the semiconductor switch is switched to operate depending on whether this voltage is higher or lower than the reference voltage. Alternately switching between first circuit means operating in a mode in which the current flowing through the wire increases with time and second circuit means operating in a mode in which the current flowing through the armature winding decreases with time. Therefore, a braking current corresponding to the reference voltage can be passed, and the braking force can be set arbitrarily by setting the reference voltage arbitrarily. Further, since the braking current is maintained at the set current until the speed becomes sufficiently low, effective braking with less rotation due to inertia during an emergency stop or the like becomes possible.

Further, the first circuit means, the second circuit means, the semiconductor switch group, etc., which compose the braking circuit, can also be used as circuit components for the steady operation of the rotating electric machine, so that the braking circuit is composed. In this case, it is not necessary to newly add these circuit components, signal processing can be performed at the logic circuit level, and this has an advantage that the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a braking circuit for a rotary electric machine according to the present invention.

FIG. 2 is a circuit diagram specifically showing the embodiment.

FIG. 3 is an equivalent circuit diagram of a portion related to a braking operation in the above embodiment.

FIG. 4 is an equivalent circuit diagram showing different braking operation modes of the equivalent circuit of the above.

FIG. 5 is a timing chart showing the operation of the above embodiment.

FIG. 6 is a timing chart showing the braking operation of the above embodiment.

FIG. 7 is a timing chart showing the operation when shifting to the braking operation of the above embodiment.

FIG. 8 is an equivalent circuit diagram showing another embodiment of the braking circuit of the rotating electric machine according to the present invention.

FIG. 9 is an equivalent circuit diagram showing different braking operation modes of the equivalent circuit of the above.

FIG. 10 is a circuit diagram of the above embodiment.

FIG. 11 is a circuit diagram showing an example of a braking circuit of a conventional rotating electric machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotating electric machine 3 armature 7 semiconductor switch group 8 current detection means 9 voltage comparator

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[Procedure amendment]

[Submission date] October 15, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a braking circuit for a rotary electric machine according to the present invention will be described below with reference to the drawings. In FIG. 1, the commercial AC power supply 14 is input to the main circuit power supply 2.
The main circuit power supply 2 has a fuse 15, diodes 16, 17, 18, and 19 for full-wave rectifying the commercial AC power input via the fuse 15, and a capacitor C for smoothing the rectified DC. It becomes. Both ends of the capacitor C are connected to a DC power source 20, and the DC power source 20 supplies power to each circuit described later. Here, the rotary electric machine is a DC brushless motor. The DC brushless motor 1 has a field composed of a magnet and also has an armature winding 3 having a three-phase structure. DC power is supplied to each armature winding 3 from the main circuit power supply 2 via the semiconductor switch group 7.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

In the a mode shown in FIG. 4 (a), the armature current ia (t) flowing out of Ea passes through R, L and D1 and is then shunted to Db2 and Db3. The child current ib (t) returns to Ea via L, R, and Eb, and the current shunted to the Db3 side is the armature current ic (t).
Return to Ea via L, R, Ec. In analyzing this equivalent circuit, the forward voltage of each diode is at a level that has no influence, so this is ignored. The following differential equation holds in the a mode.

## EQU1 ## Ea-Ria (t) -L {dia (t) / dt} =-Eb + Rib (t) + L {dib (t) / dt} =-Ec + Ric (t) + L {dic (t) / dt}

Ia (t) = ib (t) + ic (t) If this is solved for ia (t),

[Equation 3] Becomes

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

The following differential equation holds for the a mode.

## EQU00007 ## Ea = Ria (t) + L {dia (t) / dt} Solving this

[Equation 8] Becomes The following equation is similarly established for the b mode.

Ea−Vc = Ria (t) + L {dia (t) / dt} If this is solved,

[Equation 10] Becomes

[Procedure amendment 4]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 10

[Correction method] Change

[Correction content]

[Figure 10]

Claims (1)

[Claims] 1. A braking circuit of a rotating electric machine for electrically braking a rotating electric machine having a field, comprising first circuit means for increasing the magnitude of a current flowing through an armature winding of the rotating electric machine with time. Second circuit means for reducing the magnitude of the current flowing through the armature winding of the rotating electric machine with time, current detecting means for detecting the current flowing through the armature, output voltage and reference voltage of the current detecting means And a semiconductor switch group for alternately connecting and switching the first circuit means and the second circuit means by the output of the voltage comparator. Braking circuit for rotating electric machines.