JPH0130397B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a control device that controls the speed of a commutator motor using a semiconductor control element.

(Objective) The object of the present invention is to control the speed of a series-wound commutator motor using an AC power supply, and to control the speed of the motor by full-wave rectification of the power supply current using a semiconductor control element. In a control device that operates, there is a period in which the supply current to the armature of the motor and the freewheel current, which determine the firing phase of the semiconductor control element and provide a feedback effect regarding the motor operating speed, are not flowing (hereinafter abbreviated as motor non-energization). ), the motor speed electromotive voltage is effectively taken out over all its phases, and ignition is controlled using this voltage, thereby stably obtaining a larger amount of feedback than before. This is what we are trying to provide.

(Prior Art) Conventionally, various control devices of this type have been proposed that control the ignition phase while comparing a reference voltage for setting the speed with a voltage related to the motor speed electromotive force. However, this type of motor has disadvantages such as a small maximum feedback amount and slow feedback response when torque fluctuations are large.

(Solution Means) The present invention was devised to eliminate the above-mentioned drawbacks, and in controlling the firing of a semiconductor control element for controlling the phase of the current supplied to the motor, A detection circuit is provided to detect a section in which the supply current and freewheel current are flowing (hereinafter referred to as motor energization) and a non-energized state, and the speed electromotive force of the motor is extracted over all phases during the non-energized state, and This remains effective at least until de-energization through subsequent energization, while the speed is set or includes an operation to specify the speed, which consists of a sawtooth waveform where it becomes synchronized with the supply voltage. A specified voltage is generated, the voltage and the held speed electromotive voltage are compared every half cycle of the power supply, and an ignition circuit of the semiconductor control element is activated for each phase in which the speed specified voltage exceeds the speed electromotive voltage. The purpose is to determine the firing phase. If the speed specifying voltage specifies, for example, a higher speed, the slope of the sawtooth wave will be steeper, and the firing phase will therefore advance, and in this way, by choosing the slope appropriately, it can be applied to almost the entire range. It becomes possible to adjust the firing phase over time. When the motor load increases, for example, the speed electromotive voltage decreases, and the voltage that is maintained also decreases, and the speed specified voltage always exceeds this, causing the ignition phase to advance and the motor rotation speed to decrease. It is meant to compensate.

(Example) To explain an example of the present invention using figures, the first example is as follows.
The figure is a control circuit diagram, in which e is an AC power supply,
SW ₁ is the power switch, M is the commutator motor, and Ar
is its armature, St is likewise its field coil, D ₁ ,
_D2 is a diode for supplying current to the motor;
Similarly, SCR ₁ and SCR ₂ are thyristors for supplying current, and these D ₁ , D ₂ , SCR ₁ and SCR ₂ constitute a mixed bridge circuit for full-wave phase control.
_D3 is a diode for detecting armature current, and detects the forward voltage drop by connecting multiple diodes in series. D ₄ is a freewheeling diode,
When the thyristors SCR ₁ and SCR ₂ transition from the ignition state to the cutoff state, a holding current circuit of the field coil St is configured in order to continue excitation for a short time,
It also forms a path for taking out the speed electromotive force, which will be described later. Similarly, _D5 is a freewheeling diode, which short-circuits the voltage generated by the armature Ar when the thyristors _SCR1 and _SCR2 shift to the cut-off state. Diode _D6 forms a path for taking out the speed electromotive force.
Diodes D ₇ and D ₈ together with diodes D ₁ and D ₂ constitute a full-wave rectifier bridge, and thyristors SCR ₁ ,
In order to control the ignition of SCR ₂ , a full-wave rectified voltage V _A of the power supply voltage e is supplied. ZD ₁ is a Zener diode, C ₁ is a smoothing capacitor, and R ₁ is a resistor, which supplies a constant voltage Vcc for the ignition control. Note that G is a level line of 0 voltage.

ZD ₂ is a Zener diode that operates in response to a voltage V _A , and its Zener voltage is very small compared to the voltage V _A , and it is conductive over almost all phases except for the vicinity of 0 voltage of the voltage V _A. state, and the divided voltage V _B divided by resistors R ₂ and R ₃ is the second
As shown in the waveform in the figure, only the area near where the voltage V _A is at 0 potential is at 0 potential. The voltage constitutes the base voltage of the transistor _Tr1 , and is a flat voltage except for zero potential due to the voltage characteristics between the base and emitter.

In FIG. 2, the horizontal axis below the voltage V _A represents time (t), and the numbers on the vertical axis represent each voltage (volt) in FIG. 1. t ₀ indicates the time when switch SW ₁ is turned on. The collector of the transistor Tr ₁ is connected to the base of the transistor Tr ₂ and receives the voltage Vcc through the resistor R ₄ , and the voltage
When V _B is 0, the transistor Tr ₁ becomes non-conductive, which causes the transistor Tr ₂ to become conductive.
A capacitor C 2 is connected between the collector and emitter of the transistor Tr ₂ , and when the transistor Tr _{2 is non-conducting, the capacitor C 2 is} connected to the speed controller switch SW ₂ , the controller variable resistor VR, and the fixed resistor.
It is charged through _R5 and rapidly discharges when the transistor becomes conductive. As shown in FIG. 2, the voltage Vc forms a sawtooth wave every half wave of the power supply e after the switch SW ₂ is closed at time t ₁ .
COMP ₁ is an oven collector operational amplifier, and its inverting input terminal (-) receives a minute voltage obtained by dividing the voltage Vcc by resistors R ₆ and R ₇ . The non-inverting input terminal (+) receives voltage Vc, detects the open/closed state of switch SW ₂ , and output voltage V _D flattens every time voltage Vc slightly exceeds 0 potential after time _t1 . It becomes a potential. R ₈ is the load resistance for the oven collector. Voltage
V _D is charged to capacitor C ₃ through resistor R ₉ ,
The charging voltage V _E becomes almost flat as shown in FIG.
When the switch SW ₂ is opened and the voltage V _D becomes 0 potential continuously, the voltage V _E is connected to the resistor R ₉ and the operational amplifier COMP _1.
It is designed to be rapidly discharged through the . When the controller switch SW ₂ is open, that is, when the voltage V _E becomes 0, the transistor Tr ₃ becomes non-conductive and detects the controller operation state. R ₁₀ is its base resistance. COMP ₂ is an oven collector operational amplifier, and its non-inverting input terminal (+) receives a sawtooth wave voltage Vc. And the inverting input terminal (-) has a voltage related to the motor speed electromotive force.
By receiving V _F and outputting it for each phase in which the voltage Vc exceeds it, the magnitude of the speed electromotive voltage is evaluated and the thyristor firing phase, which will be described later, is determined. The operational amplifier also has the voltage _VF at the inverting input terminal (-) set to a sufficiently higher potential than the voltage Vc so as not to fire the thyristor when the switch _SW2 is open. That is, the collector of the transistor Tr ₃ receives the voltage Vcc through the resistor R ₁₁ and is connected to the base of the transistor Tr ₄ , and the collector of the transistor receives the voltage Vcc through the resistor R 11.
connected to the base of transistor Tr ₅ through R ₁₂ and when switch SW ₂ is open, transistor Tr ₃
is non-conductive, and transistors Tr ₄ and Tr ₅ are made conductive to apply voltage Vcc to the inverting input terminal (-) of operational amplifier COMP ₂ . _R13 is a resistance between the base and emitter of the transistor _Tr5 . Capacitor _C4 is for ensuring that the voltage related to the speed electromotive force becomes a smoothed voltage _VF ,
_R14 is its discharge resistance. The transistor Tr ₆ receives the output voltage V _G of the operational amplifier COMP ₂ as a base, and conducts every time this voltage is generated, causing the transistor Tr ₇ to conduct, and at that time, the speed control thyristors SCR ₁ and SCR ₂ It is designed to ignite either one of the two. R ₁₅ is a load resistance similar to R ₆ ,
R ₁₆ is the load resistance of transistor Tr ₆ , R ₁₇ is the base and emitter resistance of transistor Tr ₇ , C ₅ is the capacitor for preventing malfunction of the transistor, R ₁₈ is the gate current limiting resistance of thyristors SCR ₁ and SCR ₂ , and the resistance R ₁₉ and capacitor C ₆ are used to prevent erroneous firing of each thyristor, and resistors R ₂₀ and R ₂₁ are used to balance firing between the thyristors. Tr ₈ is a transistor for detecting the motor armature current, which receives the forward voltage drop of the diode D ₃ at its base through the resistor R ₂₂ and becomes conductive, and when the current disappears, that is, the thyristor SCR ₁ , When the armature current through the freewheeling diode _D5 becomes 0 after SCR ₂ is extinguished, it becomes non-conducting and the transistor
When Tr ₉ and Tr ₁₀ conduct, the speed electromotive voltage of the motor M at that time is transferred to the inverting input terminal (-) of the operational amplifier COMP ₂ via the diode D ₄ , transistor Tr ₁₀ , etc.
It is beginning to be given to R ₂₃ is the load resistance of transistor Tr ₈ provided to determine the base voltage of transistor Tr ₉ , R ₂₄ is the transistor
Resistance between the base and emitter for determining the base potential of Tr ₁₀ , R ₂₅ is the load resistance of transistor Tr ₉ ,
Resistor R ₂₆ cooperates with resistor R ₁₄ to divide the speed electromotive voltage to generate voltage V _F , and capacitor C ₄
This works together with the charge time constant to provide the charging time constant at that time.
V _H , V _I , and V _J are the motor terminal voltage, the armature current detection voltage, the speed electromotive voltage when the motor current is cut off, and the supply voltage when the switch SW ₂ is released.

The operation of the above configuration will be explained below.
When the power switch SW ₁ is closed at time t ₀ , the voltage V _A becomes a full-wave rectified voltage from then on. transistor
Tr ₁ becomes non-conductive for only a minute period due to the voltage V _B which becomes 0 during a minute period when the voltage V _A is near 0, and at that time supplies the base voltage to the transistor Tr ₂ and switches the controller switch SW ₂
If V B is closed at time t ₁ , the transistor becomes conductive and the capacitor becomes 0 every time the voltage V _B becomes 0.
The charge on _C2 is discharged, and during the non-conducting period, it is charged through the controller variable resistor VR and resistor _R5 , generating a sawtooth wave Vc. When the switch SW ₂ is open, the voltage Vc is 0, so the voltages V _D and _VE are 0, the transistor Tr ₃ is non-conducting, and the transistors Tr ₄ and Tr ₅
is conductive, the charging voltage V _F of the capacitor C ₄ is the voltage Vcc, the voltage V _G is 0, and the transistors Tr ₆ and Tr ₇ are non-conductive, so the thyristor
SCR ₁ and SCR ₂ are not firing. Consider a case in which the switch SW ₂ is closed at time t ₁ and the motor speed is specified to be low by setting the variable resistance VR to a relatively large value, for example. The slope of voltage Vc is based on its specification. When voltages V _D and V _E are generated, transistor Tr ₃ becomes conductive, and transistors Tr ₄ and Tr ₅ become non-conductive, the charge in capacitor C ₄ is discharged through resistor R ₁₄ , and at time t ₂ The voltage Vc is the voltage
A voltage V _G is generated in the phase exceeding V _F ,
Transistors Tr ₆ and Tr ₇ become conductive and become a thyristor.
SCR ₁ and SCR ₂ (one of them) is fired, motor terminal voltage V _H is supplied, and motor M starts rotating. Then, when the voltage Vc becomes 0, the voltage _VG becomes 0, and the thyristors SCR ₁ and SCR ₂ are extinguished at a phase t ₃ slightly delayed from this. Then, the motor terminal voltage V _H becomes 0, but the freewheel current in the path of the diodes D ₃ , D ₅ and the armature Ar continues to flow until time t ₄ due to the inductance of the motor terminal Ar. Meanwhile, transistor Tr ₈ becomes conductive due to the forward voltage drop V _I of diode D ₃ , and transistors Tr ₉ ,
Tr ₁₀ is non-conducting. Capacitor C ₄ continues to discharge and voltage V _F drops further. When the armature current disappears at time _t4 , the transistor _Tr8 becomes non-conductive, the transistors _Tr9 and _Tr10 become conductive, and the armature Ar generates a small speed electromotive voltage proportional to the motor speed. This is usually based on the residual magnetism of the field St, but generally the inductance of the field St is significantly larger than that of the armature Ar, so
In the circuit of FIG. 1, the freewheeling current through the freewheeling diode _D4 is considerably increased over that due to normal remanence.
This speed electromotive force is generated by diode D ₄ , transistor Tr ₁₀ , resistors R ₂₆ , R ₁₄ , diode D ₆ , armature
It forms a microcurrent circuit using Ar as a path.
The forward voltage drop across diode D ₆ is shown as voltage V _I . The speed electromotive force is hardly attenuated because the inductance of the field St is sufficiently large. The speed electromotive force at this time is shown as the motor terminal voltage V _H , and is further enlarged and written as the voltage V _J.
It is shown to be approximately 15 volts. The voltage V _F of the capacitor C ₄ increases slightly in accordance with the voltage V _J.
When the voltage Vc exceeds the voltage _VF at time _t5 , the thyristors SCR ₁ and SCR ₂ are fired, and the voltage _VF gradually decreases, and after extinguishing, it rises due to the speed electromotive force, and these capacitors The charging and discharging of C ₄ and the ignition and extinguishing of thyristors SCR ₁ and SCR ₂ are performed by the power source e.
Repeat every half cycle. Note that every time the voltage Vc becomes 0, V _D becomes 0, but the voltage V _E of the capacitor C ₃
The value of discharge resistance _R8 is set so that it does not become 0 while switch _SW2 is closed.
Therefore, since the transistor Tr ₃ does not become non-conductive at this time, the capacitor C ₄ is not charged by the voltage Vcc.

Next, when a heavy load is applied to the motor M at time t ₆ , the rotation speed decreases and the motor load current increases, and after the thyristors SCR ₁ and SCR ₂ are extinguished, that is, after the voltage V _H becomes 0. The current through the freewheeling diode D ₅ in flows for a longer time,
At phase _t7 , which is delayed compared to when the load is light, the motor speed becomes slower than before, so the speed electromotive force increases.
As V _J becomes lower, capacitor C ₄ continues to discharge and voltage V _F decreases. Therefore, in the more advanced phase _t8 , the voltage Vc exceeds the voltage _VF , so that the firing phases of the thyristors _SCR1 and _SCR2 advance. The capacitor _C4 repeats charging and discharging in the same manner as described above, and the voltage level of _VF decreases to a point commensurate with the decrease in the speed electromotive voltage _VJ , so that equilibrium occurs when the ignition phase further advances. Therefore, the effective voltage applied to the motor M increases and the motor M is driven more powerfully.

Next, when the load on the motor M becomes heavier and the rotation stops, the speed electromotive voltage V _J becomes 0, the transistor Tr ₁₀ does not become conductive, and the capacitor C ₄ continues discharging until the voltage becomes 0, and the time _t10
In this case, thyristors SCR ₁ and SCR ₂ are in operation over almost all phases. That is, variable resistance VR
Even if motor M is specified as low speed
The maximum effective voltage is applied to the motor to release it from the locked state. This means that the feedback effect which this type of motor requires especially during low speed operation is very strong.

Figure 3 shows the voltages at various parts when the motor M is operated at high speed under normal load with the controller variable resistance VR set to a small value, in the same way as in Figure 2.
Compared to FIG. 2, the slope of voltage Vc becomes steeper and indicates that the charging of capacitor _C2 is saturated to some extent. Since the speed electromotive force V _J is large, the voltage
Although V _F also increases, since the slope of voltage Vc is large, thyristors SCR ₁ and SCR ₂ are fired in relatively advanced phases, and a voltage close to the full voltage is applied to motor M. And since the speed electromotive voltage V _J is large,
After the phase t ₁₁ of the motor terminal voltage V _H that exceeds the voltage due to the power supply voltage e, the motor current is suppressed and the phase t ₁₂ is just before the power supply voltage e becomes 0.
At this point, the thyristors SCR ₁ and SCR ₂ are extinguished, the armature current becomes 0, and only the speed electromotive force remains. From that point on, the voltage V _F increases, but since the rising tendency of the voltage Vc is large, at a relatively advanced phase t ₁₃ , V _F <Vc and the thyristors SCR ₁ and SCR ₂ fire. In high-speed operation, the speed electromotive force _V Similarly, depending on the increase or decrease of
t ₁₃ moves left and right, creating a feedback effect. Note that the voltage Vc is set according to a saturation curve, which contributes to preventing abnormally high speeds when the load becomes light.

(Effects) As described above, according to the present invention, the motor speed electromotive force is extracted and held over all phases when the motor is not energized, and the sawtooth wave is generated over all phases starting from the minimum value of the power supply waveform. Then, the firing phase of the motor control thyristor is determined by comparing it with the held value of the speed electromotive force, so if the motor load becomes very heavy and the speed electromotive force becomes minute, the firing phase will be set to the minimum value of the power supply waveform. As the motor approaches , the motor will be driven at full voltage, and this means that even if the firing angle of the thyristor is small to operate the motor at low speed, the motor will be driven at almost full voltage due to load fluctuations. The firing angle will be increased resulting in a strong feedback effect. As for responsiveness to load fluctuations, by appropriately setting the charging/discharging time constant of capacitor _C4 , high-speed response can be achieved without interfering with other circuit conditions.

[Brief explanation of drawings]

FIG. 1 is a control circuit diagram showing an embodiment of the present invention, and FIGS. 2 and 3 are waveform diagrams of various parts for explaining its operation. In the figure, e is an AC power supply, SCR ₁ and SCR ₂ are semiconductor control elements, M is a commutator motor, a diode D ₃ and transistors Tr ₈ and Tr ₉ are main elements of the detection device,
Transistor Tr ₁₀ is the main element of the speed electromotive force extraction device, capacitor C ₄ is the main element of the holding device,
Zener diode ZD ₂ and transistor Tr ₁ ,
Tr ₂ , controller variable resistance VR and capacitor C ₂ are the main elements of the speed specified voltage generator,
COMP ₂ is a comparator, and transistors Tr ₆ and Tr ₇ are the main elements of the ignition device.

Claims (1)

[Claims] 1 In a device that uses a semiconductor control element to control the full-wave phase of the current supplied to a series-wound commutator motor from an AC power supply, the presence or absence of each current of the current supplied to the armature of the motor and the freewheel current caused by this current. a detection device that continuously detects the current as the cycle of the AC power source progresses; a speed electromotive force extraction device that extracts the speed electromotive force of the motor over all phases in which the current does not flow; A holding device temporarily holds a sawtooth waveform that is synchronized with every half wave of the AC power source, each of the sawtooth waves equivalently spanning the entire half wave of the AC power source, and the slope of the waveform depending on the motor speed. A speed designation voltage generation device that generates a voltage corresponding to the specified speed, and a voltage of the speed designation voltage generation device and a voltage of the holding device are compared in accordance with changes in the AC power supply phase to control the semiconductor. A speed control device for a commutator motor, comprising: a comparator that generates a firing phase control signal for an element; and an ignition device that fires the semiconductor control element in accordance with the firing phase control signal.