JPH04190693A - Circuit for controlling energizing of inductance load - Google Patents

Abstract

PURPOSE:To make the energizing current of an inductance load to quickly rise by energizing the first and second semiconductor switching elements and adding the high voltage of a small-capacitance capacitor and DC power supply voltage to each other when the energizing current decreases to a prescribed value. CONSTITUTION:The magnetic energy accumulated in an inductance load 1 tends to return to the positive pole 2a of a power source due to diodes 4a and 4b, but the energy is blocked by a diode 6 and gives a charge of electricity of a polarity to a capacitor 5. Since the capacitor 5 has a small capacity, the voltage across the capacitor 5 rises and the excitation current abruptly decreases. When the excitation current decreases to a prescribed value, the output of the capacitor 5 is returned to a high level by means of the hysteresis characteristic of an operational amplifier 11. As a result, the excitation current is quickly increased by a high voltage obtained by adding the high voltage of the capacitor 5 and a power supply voltage to each other, and then, further increased by the power supply voltage, since transistors 3a and 3b are conducted. Therefore, no high voltage is required for the power supply voltage, because the voltage which can produce the energizing current of the inductance load 1 is sufficient.

Description

[Detailed Description of the Invention] [Industrial Application Field] Used to control the current flowing through the armature coil of a motor with an output of 30 watts or more in a specified waveform when rotating at high speed. .

Furthermore, in controlling the current of the electromagnet of the magnetic bearing, since the inductance of the excitation coil is large, it is difficult to rapidly change the current flowing to levitate one rotor. Such difficult problems are obviated by utilizing the measures of the present invention.

[Conventional technology]

In order to improve the responsiveness of the chopper circuit for the current flowing through an inductance load, if the inductance load is large, the power supply voltage should be increased accordingly (so that the current rises rapidly, and the accumulated magnetic field caused by the inductance is By circulating energy back to the power source, the current flow is controlled by rapidly reducing the drop in current flow and increasing responsiveness.

r Problems to be solved by the present invention] [Prior art]
As explained in the section above, in order to increase the responsiveness of the current flowing through a large inductance load using a chopper circuit,
There are means to increase the power supply voltage, but in order to obtain faster response, the power supply voltage becomes significantly higher, which poses the problem of impracticality.

For example, in the case of an induction motor or a reluctance type motor with an output of SOO Watts, in order to make the chopper control pulse of the armature current several microseconds, the voltage applied to obtain the driving torque must be 5 to 70 times. voltage is required,
There is a problem that practicality is lost.

The above-mentioned problems are exactly the same drawbacks in controlling the excitation coil of the electromagnet of the magnetic bearing.

[Means for solving the problem] The first means is a direct current that is supplied to the inductance load through the first and second semiconductor switching elements connected to both ends of the inductance load, and the first and second semiconductor switching elements. A first diode connected in reverse to a series connection of a power supply, a first semiconductor switching element and an inductance load, and a second diode connected in reverse to a series connection of a second semiconductor switching element and an inductance load. A diode, a current detection circuit that detects the current flowing through an inductance load and obtains a detection voltage, a reference voltage of a set arbitrary waveform voltage, and a reverse current inserted in the forward direction on the DC power supply side that supplies power to the inductance load. A prevention diode, a small capacitor connected in parallel to the reverse flow prevention diode,
When the detection voltage of the current detection circuit exceeds the reference voltage, the first
The semiconductor switching element is made non-conductive to prevent the accumulated magnetic energy of the inductance load from flowing into the positive electrode side of the DC power supply as a current by the backflow prevention diode, and the above-mentioned method is carried out through the first and second diodes. By converting the stored magnetic energy into electrostatic energy in a small-capacity capacitor and charging it to a high voltage, the conduction current is rapidly decreased, and when the current decreases to a predetermined value, the first and second semiconductor switching elements are made conductive. It consists of a chopper circuit that uses a high voltage that is the sum of the high voltage of a small-capacity capacitor and the DC power supply voltage to cause the current to rise quickly.

The first . n sets of semiconductor switching elements, ``and second, ■, and...'', and
and a DC power supply that supplies power to each of the n sets of inductance loads through the n sets of semiconductor switching elements U2 and . a current detection circuit that detects the current flowing through each of n sets of inductance loads to obtain n detection voltages, and a rectangular wave electric signal of a predetermined time width separated by a predetermined time. are arranged in sequence, and are inserted in the forward direction into an electrical circuit that generates n sets of electrical signal trains whose phases are delayed by a predetermined time, and into a DC power source that supplies power to n sets of inductance loads. The above-mentioned n sets of electrical circuits include n backflow prevention diodes, n small-capacity capacitors connected in parallel to the backflow prevention diodes, and semiconductor switching elements connected to both ends of the n sets of inductance loads. Each of the signal trains conducts the corresponding inductance load, and when the n detection voltages obtained from the current detection circuit exceed a set value, the semiconductor switching elements connected across the inductance load are turned non-conductive. Then, a backflow prevention diode prevents the accumulated magnetic energy of the inductance load from flowing into the positive electrode side of the DC power supply as a current, and the accumulated magnetic energy is converted into electrostatic energy of a small capacitor via the reversely connected diode. By converting and charging, the current is rapidly reduced, and when it drops to a predetermined value, the semiconductor switching element connected across the inductance load is made conductive, and the voltage of the small capacitor and the DC power supply voltage are added together. When the chopper circuit that causes the current to rise quickly due to the applied voltage and the inductance load that is energized by chopper control is stopped at the end of the electric signal in the electric signal train. A backflow prevention diode prevents the accumulated magnetic energy of the inductance load from flowing into the positive pole side of the DC power supply as a current, and the entire amount of the accumulated magnetic energy is converted into electrostatic energy of a small capacitor via the reversely connected diode. - By switching the current and charging it to a high voltage, the conducting current rapidly drops and disappears, and when the inductance load starts to be energized at the beginning of the next electric signal, the small-capacity capacitor It is composed of an electric circuit that uses a high voltage that is the sum of the high voltage of the current and the DC power supply voltage to cause the current to rise quickly.

[Effect]

The embodiment shown in FIG. 1(a) will be described.

The excitation current of the inductance load l (voltage drop across the resistor 9, that is, the output via the absolute value circuit IO) is set to the reference voltage (terminal/2
When the voltage exceeds (voltage 1), the output of the operational amplifier // becomes low level, and the output via the amplifier circuit 7 disappears, causing the transistors 3a and 3b to become non-conductive.

The stored magnetic energy of load l is transferred to diode a.

+b attempts to circulate the current to the positive electrode of the power supply, 2a, but this is blocked by diode B, charging capacitor j to the polarity shown.

Since the capacitor S has a small capacitance, the voltage rises and the excitation current drops rapidly, and when it drops to a predetermined value, the operational amplifier/
The output returns to high level due to the hysteresis characteristic of /.

Therefore, since the transistors 3a and jb are conductive, the high voltage that is the sum of the high voltage of the capacitor S and the power supply voltage causes
The excitation current rises rapidly and then rises further with the supply voltage. When the excitation current exceeds the reference voltage, the transistors 3a and 3b become non-conductive again, forming a chopper circuit.

The smaller the capacitance of the capacitor S, the thicker the chopper frequency (
can. Therefore, the power supply voltage only needs to be the voltage that corresponds to the current value of the inductance load l.

This has the effect of eliminating the need for high voltage as in known means.

In the embodiment shown in FIG. 1(C), when the input electric signal to the terminal l core a, /co b is a square wave, the inductance load /co. , /a, the rise and fall of the energizing current (excitation current) are rapid, and it is possible to obtain a energizing waveform that approximates a rectangular wave.

Therefore, when the inductance load is an armature coil of a DC motor, high speed rotation is possible.

〔Example〕

The details of the apparatus of the present invention will be explained with reference to the embodiments shown in FIG. 1 and subsequent figures. Components with the same symbols in the drawings are the same members, so a redundant explanation will be omitted.

In FIG. 1(a), the symbol 1 is an inductance load, for example, an excitation coil of a magnetic bearing. The magnetic core of the coil is omitted and not shown.

At both ends of the inductance load l, a transistor 3a,
3b is connected, and diodes lIa and llb are reversely connected to each transistor and inductance load l.

The excitation current is detected as a voltage drop across the resistor, and is rectified by an absolute value circuit (rectifier circuit) 10, the output of which is input to one terminal of an operational amplifier/I.

The input to the + terminal is the reference voltage of terminal/2.

The reference voltage is the song in the time chart in Figure 2! An example is shown as #, 19.

The inductance load l is caused by the DC power supply terminals Ja and 2b.
is supplied with power through a diode 6 connected in the forward direction.

When the reference voltage is input to the operational amplifier // shown by the curve /q in Figure 1, the output of the operational amplifier l/ becomes high level,
The output is amplified by the amplifying circuit 7, and then passed through the inverting circuit,
Transistor 3a becomes conductive.

At the same time, transistor 3b also becomes conductive.

Therefore, the inductance load l is energized, and the excitation current rises as shown by the dotted line curve /S in FIG. 2, and energization is started.

When the voltage drop across the resistor (proportional to the excitation current) exceeds the voltage at the child terminals of the operational amplifier, the operational amplifier
Since the output of / changes to low level, transistor 3
a and 3b become non-conductive.

It is a well-known method that the large magnetic energy accumulated in the inductance load l is circulated as a current to the positive terminal side of the power supply through the diodes 4 (a, da b) and is dissipated. However, in the device of the present invention, Since the above-mentioned reflux is blocked by the backflow prevention diode B, the small capacity capacitor S is charged to a high voltage.

Therefore, the current drops rapidly, and when it drops by a predetermined value,
Due to the hysteresis characteristics of the operational amplifier //, its output returns to high level.

Therefore, the transistors Ja and 3b become conductive, and the exciting current rapidly rises due to the charging voltage of the capacitor S.
When the output of the absolute value circuit 10 increases to a voltage corresponding to the curve / in the figure, the transistors 3a and 3b become non-conductive again.

A chopper circuit repeats such cycles, and the excitation current curve /S of the inductance load / is proportional to the curve /q (reference voltage).

The current curve at the bottom shows the above-mentioned chopper action in a time-enlarged manner only in the vicinity of the dotted line 16 in FIG.

Point Ih/4'a is an enlarged view of the excitation current proportional to the reference voltage/lI. curve/! ; a , /
! b, . . . indicate the pulsating current actually flowing through the inductance load l.

When transistors 3a and 3b conduct, the song i13! B
The current rises as shown in a, but at this time, the rise of the current becomes rapid due to the high voltage caused by the electrostatic energy stored in the capacitor S.

When it rises to the dotted line /lIa, the transistor Ja.

3b becomes non-conductive, so the current drops as shown by curve lSb. At this time, the magnetic energy stored in the inductance load charges the capacitor S to a high voltage, so that the voltage drops quickly.

By repeating this cycle, the excitation current changes with the upper limit of the curve /Qa.

Curve /j; a, /! The time width of ;b, .

The above fact is because the interface load l and capacitor S have similar properties to a parallel resonant circuit.

This is also inferred from the fact that the capacitance of the capacitor S is small (indeed, the resonance frequency becomes large).

Only the Joule loss due to the resistance of the inductance load l is supplied from the DC power supply at the end of the current rise.

According to well-known means, the current rises rapidly by increasing the direct current power supply voltage so that magnetic energy is stored rapidly, and the current falls quickly by circulating the stored magnetic energy back to the power supply.

Therefore, the applied voltage becomes a high voltage, and the chopper frequency (
curve/! ;a,/! ;b,...) There is a limit to reducing the time width.

Therefore, the width of the arrow g of the reference voltage curve /II is small.
When it comes to about 0 microseconds, there is a drawback that a response with a small time constant corresponding to irregularities as shown in curve /41 is impossible.

According to the device of the present invention, even if the applied voltage is lowered, the response speed can be increased by reducing the capacitance of the capacitor S.

According to actual measurements, when controlling the energization of the excitation coil of the magnetic pole of a reluctance type motor with an output of about 300 watts, the curve /ja, /! with an applied DC voltage of 100 volts.
;b,... have a width of 0. ! f microsecond. The capacitance of the capacitor S at this time is 0.7 microfarads.

Therefore, even in the case of a large inductance load, the excitation current can be controlled with good responsiveness.
By controlling the energization of the excitation coil of the electromagnet of the magnetic bearing, there is an effect that the magnetic levitation of the rotating body can be carried out more accurately.

If a high-speed switching element such as an IGBT is used in place of the transistors Ja, 3b, the above-mentioned response will be even better.

Song in Figure 2 + 1j! If llI is a sine wave, the means of the present invention can be used for the inverter, so a high-speed induction machine with high speed and little vibration can be obtained.

In FIG. 1(a), the diode 6 is inserted on the power supply positive terminal side, but the present invention can also be carried out even if it is inserted in the forward direction together with the capacitor 3b at the position indicated by the dotted line 6a on the power supply negative terminal 2b side. I can do it.

The embodiment shown in FIG. 1(1)) is a modification of the chopper circuit. In FIG. 1(b), as the excitation current increases, the voltage drop across the resistance increases as the voltage at the reference voltage terminal 12 (second
When the curve /lI) in the figure is exceeded, the output of the operational amplifier l/ converts to a high level. From this output, a differentiated pulse at the rising edge is obtained by the differentiating circuit //a, and since the differential pulse energizes the monostable circuit /3, an electric pulse during a predetermined time is obtained. This electric pulse is sent to the inverting circuit. /Ja is inverted, energizing transistors 3a and 3b and making them non-conductive.

During the electrical pulse mentioned above, the curve /jb in FIG.
,/! ; is made equal to the width of d, .

The time width of such an electric pulse is determined in accordance with the capacitance of the capacitor S, and a chopper circuit with desired responsiveness can be constructed, which is another means for carrying out the present invention.

The embodiment shown in FIG. 1(C) has not one inductance load but two or more n inductance loads (n==2,3゜q...
・) This is a case where the means of the present invention is applied to a certain case. n
The case of = ko will be explained.

The energization control of the inductance load l is performed in the same manner as in the case of FIG. 1(a).

Similar energization control is performed for the inductance load λ.

What differs from the previous embodiment is the electrical signals input from terminals /2a and /2b.

In the time chart of Figure 3, the curve /? a.

/? b, . . . are rectangular waves with equal time widths, and are electrical signal sequences in which electrical signals spaced apart from each other by equal time widths are sequentially arranged.

Specifically, the above-mentioned electric signal is used to control the energization of the armature coil of the l-phase magnetic goose of a reluctance motor, for example.
This is a phase position detection signal, which is generated by an electrical circuit that includes a position detection element.

The electric signals of curves /7a, /7c, ... are input to terminal /2a, and the electric signals of curves /7a, /7c, etc. are input to terminal /b.
+, /? Electrical signals of d, . . . are input.

When the electrical signal of curve /7a is input to terminal /2a,
As in the previous embodiment, the inductance load l has the curve /7
A chopper circuit conducts current in proportion to the height of a.

At the end of curve /7a, the input to terminal /2a disappears, so transistors ja, 3b turn non-conducting, and the stored magnetic energy charges capacitor S as a current through diodes a, 4(, b). and high voltage.

Next, curve /? to terminal l/b? The electric signal of b is input to terminal /2b. Since the input to one terminal of the operational amplifier //a (the voltage drop across the absolute value circuit 10a, that is, the voltage drop across the resistor 9a) is smaller than the input signal to the terminal /2b, the output of the amplifier circuit 7a causes
At this time, the voltage applied to the inductance load /a is the sum of the high voltage of the capacitor S and the voltage of the power supply terminal 2a, so the current rapidly rises.

After that, the current is maintained by the power supply voltage through the diode 6, and the chopping curve /? by the operational amplifier //a is maintained. The current flow is stopped at the end of b, and the stored magnetic energy of the inductance load /a is transferred to the diode lic,
1ltl, the capacitor 5 is converted into electrostatic energy and charged to a high voltage. Therefore, the current drop will be rapid.

The next curve/? Since the electrical signal c is input to the terminal /2a, the energization of the inductance load 1 quickly rises, then chopper control is performed, and the energization decreases rapidly.

In FIG. 3, the above-mentioned energization curve is the dotted line /ffa.

They are shown as igb, .

The energization angle of one phase of the well-known Y-type three-phase DC motor is 120 degrees in electrical angle, which is indicated by arrow /9a.

Since arrow /9t) has an electrical angle of 1110 degrees, the descending part of the one-conducting current curve is within the section of arrow /9b. Therefore, no counter-torque is generated, and the rising portion is also rapid. The above-mentioned situation is the same for the other curves /gh, /gc, . . . . When the motor reaches high speed, the curve /? a
, /? Although the widths of b, .

Therefore, there is an effect that the reduction in torque and efficiency is reduced even in high-speed rotation.

Particularly in a reluctance type electric motor in which the inductance of the armature coil is extremely large, the above-mentioned functions and effects are effective technical means.

The armature coils of the other two phases are energized by the same means using 62 backflow prevention diodes and capacitors, and the effects are the same.

In the case of a three-phase pulse motor, one more armature coil (inductance load/l) is added. By the block circuit A, the inductance load lb is energized in the same way as the inductance load /a.

The electrical signals input to terminal /2a have a width of Igo degrees in electrical angle and are spaced apart from each other by Igo degrees (Fig. 3).
, 20 b,... As a result, the first phase armature coil is energized. The inductance load /a is energized by the curves 2/a, 2/b, . . . in FIG. 3 that are input to the terminal /2b.

The inductance load /b is energized by the curves 22a, 22b, . . . in FIG. 3 that are input to the terminal /2c.

Curves J/a, J/b, ... are curves j6a, 20b
,...The phase is delayed by 120 degrees in electrical angle, and the curve L
la,, 12b.

... is the same <12a from curves 2/a, 2/b, ...
I'm way behind.

In general, each of the inductance loads /, /a, /b is composed of a plurality of armature coils, and is energized in the same phase.

The phases of the applied current are 120 electrical degrees apart in the order of the first, second, and third phases.

Since the current flowing through each armature coil has a waveform that approximates a rectangular wave, it is characterized by high-speed stepping.

Generally speaking, if there are n sets, there are n sets of inductance loads, that is, armature coils. One phase includes a plurality of armature coils in the same phase. n=2,3.
Da..., n.

The energization angle of the armature coils of each phase is 110 degrees in electrical angle, and they are separated by the same angle, and the phase difference is 340/n degrees (electrical angle). There are also n sets of electrical signals that control energization, and each set The electrical signals each have a width of 1110 electrical degrees and are spaced apart by the same angle. Further, the electrical signals of each phase are sequentially delayed in phase by 360/n degrees.

The above expression is for n sets of DC motors, but in the case of n sets of stepping motors, the electrical angle is 11
It can be expressed as a predetermined time width T, not 0 degrees, and that the electrical signals of each phase are delayed by 2 T/n.

Each of the n sets of inductance loads is provided with n backflow prevention diodes and n small capacitors connected in parallel to these diodes.

〔effect〕

A large inductance load requires time to store and release magnetic energy, so in order to perform energization control with good responsiveness, there is a well-known means of using a chopper circuit that increases the applied voltage. There are limits to sexuality.

According to the means of the present invention, there is an effect that the applied voltage can be lowered and the energization control of the inductance load can be performed with better response.

It is particularly effective to apply the technique of the present invention to a reluctance type electric motor with large inductance.

[Brief explanation of drawings]

Figures 1(a), (t), and (C) are electrical circuit diagrams of an embodiment of the device of the present invention, and Figure 2 is the time of electrical signals of each part of the circuit in Figures 1(a) and (b). The chart, Figure 3, is the same as Figure 1 (
The time charts of the input signals of terminals /2a, /2b, and /2c of C) are shown, respectively. /, /a, /b...inductance load, 2
a. 2b...DC power supply positive and negative terminals, 3a, 3b,...3
d...transistor! ;, Sa... Capacitor, 6.6a... Backflow prevention diode, 10,1
0a... Absolute value circuit, //, //a... Operational amplifier, /2... Reference voltage terminal, //a... Differential circuit, 13... Monostable circuit, 7,7a...・Amplification circuit, /%...Reference voltage curve. /! ;, 15a, 15b... excitation current curve,
A... energization control circuit for inductance load /b, /
7a,/? b. ..., /7d... Input signal of terminal /Ua in Fig. 1(C), /ga, Igb, ..., /A'd... Excitation current curve of inductance load l, la, 2ob
,-,2/a, ,2/b. -, 22a, :L2 b, 1 terminal/2h, /
2b, /2c input signal.

Claims (2)

[Claims] (1) First and second semiconductor switching elements connected to both ends of the inductance load, a DC power supply that supplies power to the inductance load via the first and second semiconductor switching elements, and the first semiconductor switching element. The first diode is connected in reverse to the series connection with the inductance load, the second diode is connected in reverse to the series connection of the second semiconductor switching element and the inductance load, and the current flowing through the inductance load is detected. a current detection circuit that obtains a detected voltage, a reference voltage of a set arbitrary waveform voltage, a reverse current prevention diode inserted in the forward direction on the DC power supply side that supplies power to the inductance load, and the reverse current prevention diode. When the detection voltage of the small-capacity capacitor connected in parallel with the current detection circuit exceeds the reference voltage, the first and second semiconductor switching elements become non-conducting, and the accumulated magnetic energy of the inductance load is converted into direct current. A backflow prevention diode prevents the current from flowing into the positive side of the power supply, and the stored magnetic energy is converted into electrostatic energy in a small capacity capacitor via the first and second diodes and charged to a high voltage. By doing so,
The current is rapidly reduced, and when it drops to a predetermined value, the first and second semiconductor switching elements are made conductive, and a high voltage that is the sum of the high voltage of the small-capacity capacitor and the DC power supply voltage suppresses the rise of the current. An energization control circuit for an inductance load, characterized by comprising a rapid chopper circuit. (2) The first, ■, and second
■ n sets of semiconductor switching elements and a first
A DC power supply that supplies power to n sets of inductance loads through n sets of semiconductor switching elements, , 2nd, 2, and . . . , and a series connection body of each inductance load connected to each semiconductor switching element. Reversely connected diodes, a current detection circuit that detects the current flowing through n sets of inductance loads and obtains n detection voltages, and a rectangular wave of electricity with a width of a predetermined time separated by a predetermined time. The signals are arranged sequentially, and are inserted in the forward direction into an electrical circuit that generates n sets of electrical signal trains whose phases are delayed by a predetermined time, and into a DC power source that supplies power to n sets of inductance loads. The n sets of n reverse current prevention diodes, n small capacitors connected in parallel to the reverse current preventive diodes, and semiconductor switching elements connected to both ends of the n sets of inductance loads are combined into the above n sets. The corresponding inductance load is made conductive by each electric signal train, and when the n detected voltages obtained from the current detection circuit exceed a set value, the semiconductor switching element connected to both ends of the inductance load is made non-conductive. Then, the reverse-current prevention diode prevents the accumulated magnetic energy of the inductance load from flowing into the positive electrode side of the DC power supply as a current, and the accumulated magnetic energy is transferred to the electrostatic energy of the small-capacity capacitor via the reverse-connected diode. By converting and charging the current, the current is rapidly reduced, and when it drops to a predetermined value, the semiconductor switching element connected across the inductance load is made conductive, and the voltage of the small capacitor and the DC power supply voltage are reduced. When the inductance load is energized by the chopper circuit, which uses the added voltage to make the current rise rapidly, and the chopper control of the chopper circuit is stopped at the end of the electric signal of the electric signal train, the inductance load is A backflow prevention diode prevents the stored magnetic energy from flowing into the positive pole side of the DC power supply as a current, and the entire amount of the stored magnetic energy is converted into electrostatic energy of a small capacitor through the reversely connected diode, resulting in a high By charging to a voltage, the conducting current rapidly drops and disappears, and when the inductance load starts to be energized at the beginning of the next electric signal, the high voltage of the small capacitor and the DC power supply voltage are 1. An energization control circuit for an inductance load, comprising an electric circuit that rapidly rises a energized current by using a high voltage that is added to the energization control circuit.