JPS5852438B2 - Control device for commutatorless motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that energizes a synchronous motor using an inverter comprising a semiconductor element having a self-conducting blocking ability and a feedback diode, and particularly relates to a device that energizes a synchronous motor using an inverter comprising a semiconductor element having a self-conducting blocking ability and a feedback diode. The present invention relates to a control device for a commutatorless motor, which improves the field strength of a synchronous motor and makes it possible to weaken and control the field of a synchronous motor.

Naturally commutated non-commutator motors usually use a current source inverter or current source cycloconverter as their power supply device, and operate a synchronous motor at a leading power factor, using its back electromotive voltage or power supply voltage. Although commutation is carried out, the drawbacks of this device are: (1) Since the commutation limit changes when the field current is changed, there is a limit to field weakening, and in reality, field control is hardly possible.

(2) As the commutation margin angle decreases as the load increases, the overload capacity cannot be increased.

etc. Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks, and to enable field weakening control similar to that of separately excited split-winding DC motors, and furthermore, since the overload withstand capacity does not depend on the commutation margin angle, it is possible to increase the overload capacity. An object of the present invention is to provide a control device for a commutator motor.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.
2 is a controlled rectifier that converts commercial alternating current into direct current, 2 is an inverse converter that is composed of a plurality of semiconductor elements having self-conducting blocking ability and a feedback diode (not shown), and converts direct current power into alternating current power, and 3 is a controlled rectifier. 1 a smoothing circuit for smoothing the output; 4 an armature of the synchronous motor; 5 a field magnet of the synchronous motor; 6 a position detection device connected to the synchronous motor and detecting the relative position of the armature 4 and the field 5; 7 is a speed setting device,
8 is a voltage control circuit that controls the output voltage of the control rectifier 1; 9 is a speed detection circuit that receives the output signal of the position detection device 6 and detects the speed of the synchronous motor; for example, a speed generator is directly connected to the synchronous motor; In this case, the speed detection circuit 9 can be omitted and the output of the speed generator can be used instead of the output of the speed detection circuit 9.

Reference numeral 10 denotes a commutation control circuit to which the output signal of the position detection device 6 is applied and controls the commutation timing of the inverse conversion device 2.

Here, the semiconductor element having self-current blocking ability refers to an element such as a gate Kuhn-off transistor or a transistor.

In conventional non-commutator motors, the commutating action is performed using the back electromotive force of the motor, resulting in a leading current.

That is, it is necessary to set the setting control advance angle to a certain angle to advance the current phase and commutate the current.

Since the inverter of the present invention uses an element having self-blocking ability, the set control advance angle r is independent of the back electromotive force of the motor.

can be set to 0°.

Further, in the present invention, a position detection device 6 as shown in FIG. 2 is used.

In this example, proximity switches PSUXPSV and psw are used, but the rotating magnetic body M is toothed by an angle π (electrical angle), the next angle π has no teeth, and the next angle π has teeth. It's a kirigashi.

The gear cutting portion has a wide width at the center and narrows as it approaches the ends, so that the area of the protruding portion is equivalent to a pseudo sine wave.

Moreover, there is a certain relationship between the distance between the protruding portion and the non-protruding portion, which will be explained in detail later.

The fixed part has 3 electrical angles at intervals of 2/3π, as with normal ones.
The position detectors PSUXPSV and psw are arranged.

The outputs of these three position detectors are converted into analog signals by the speed detection circuit 9 and compared with the signal from the speed setter 7, and the voltage control circuit 8 changes the gate phase of the control rectifier 1 to control the voltage.

On the other hand, the output signal of the position detector 6 is input to the commutation control circuit 10, where it turns on and off the semiconductor elements of the inverter 2.
, that is, the commutation timing.

Here, there is the following relationship between the gear cutting of the rotating magnetic body M and the above-mentioned ON and OFF timing signals.

That is, since this converter is a voltage type converter, it conducts current in the same way as a π current type, and there is a phase difference of 2π/3 in the energization period of each phase of the synchronous motor.

FIG. 3 shows a one-phase energization mode. When this waveform is expanded into a Fourier series and the n-th harmonic base En is determined, the following equation is obtained.

π Therefore, in order to remove any n1th order...n2th order harmonic component, α1 and α2 that satisfy the following may be found.

Among the harmonics, the 5th and 7th harmonics have the largest component and influence the fundamental wave component torque, so in the 2 equations, n1 = 5
By substituting n2=7, a request for α1 and α2 can be obtained.

If higher harmonics are to be removed, the number of commutations may be increased in the same manner.

The output line voltage is determined by the relationship between the energization modes of each phase, but for example, the line voltage between UV will be the 5th and 7th harmonics unless the 5th and 7th harmonics are included in the U phase and ■ phase, respectively. Since the 7th harmonic is not included, there is no influence of the torque of the 5th and 7th harmonics.

Therefore, according to the present invention: (1) Since the output voltage waveform is improved, harmonics are reduced and the synchronous motor characteristics are improved.

(2) Since an element with self-current blocking ability is used, the set control advance angle can be set to 0 degrees, and the commutation limit no longer depends on the commutation margin angle, so the overload tolerance can be increased.

(3) Since there is no need for commutation with leading current, the power factor is improved and the synchronous motor becomes smaller.

(4) Since the power factor is improved, the capacitance of the feedback diode included in the inverter 2 is reduced.

(5) Field control is possible because the commutation limit does not change even if the field current is changed.

It has excellent effects such as

FIG. 4 shows an embodiment in which automatic field weakening control of a synchronous motor can be performed by applying the present invention.
0 is the same as in FIG. 1, and 11 is a field power source 12 which is an automatic field weakening control circuit.

This example performs control similar to the field weakening control of a separately excited split-winding DC machine.The applied voltage of the synchronous motor is increased to a certain value, and when operating at a higher speed, the output voltage of the inverter 2 is is detected and the automatic field weakening control circuit 12 controls the sirisk of the field power source 11 to weaken the field current and increase the speed.

In this case, the synchronous motor characteristics become constant output characteristics.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a detailed diagram of a position detection device used in the present invention, FIG. 3 is a synchronous motor phase voltage waveform diagram according to the present invention, and FIG. 4 FIG. 2 is a block diagram showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Control rectifier, 2... Inverse conversion device, 3... Smoothing circuit, 4... Armature of synchronous motor, 5... ...Field of synchronous motor, 6...
...Position detection device, 7...Speed setting device, 8
...Voltage control circuit, 9... Speed detection circuit, 10... Commutation regulation circuit, 11...
Field power supply, 12...Medium moving field control circuit.

Claims (1)

[Claims] 1. An inverter that has a plurality of semiconductor elements and feedback diodes that have self-conducting blocking ability and converts DC power into AC power, a controlled rectifier that supplies DC power to this inverter, and this controlled rectifier. A smoothing circuit provided between the device and the inverter, a synchronous motor energized by the inverter, and a relative position between the armature of the synchronous motor and the field, and an output signal thereof. a position detection device that generates a pseudo sine wave equivalently as , a commutation control circuit to which an output signal of the position detection device is applied and controls commutation timing of the inverse conversion device, and a preset speed and a commutation control circuit that controls the commutation timing of the inverse conversion device; and a voltage control circuit that controls the output of the control rectifier according to the difference in speed from the speed of the synchronous motor, and the output voltage of the inverse converter is a pseudo sine wave. Device.