JPS638717B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a starting method for a commutatorless motor without a position detector.

[Conventional technology]

Conventionally, as a control method for this type of commutatorless motor, the position detector is omitted, and the effective magnetic flux waveform of each phase obtained by integrating the induced voltage of the motor is used as a synchronization signal for motor commutation. Methods have been proposed to improve control safety and start-up ease. In such conventional control methods for non-commutated motors, starting is possible without a position detector by giving a correct initial value to the integrator for magnetic flux calculation and storing the electrical position of the field pole. In this case, the initial value is automatically given to the integrator by turning on the field circuit prior to operation. In addition, such an integrating circuit that calculates magnetic flux is generally called a magnetic flux calculator, and in order to avoid the influence of DC drift, a PI feedback circuit is added or the input side is capacitance coupled to cut the DC component. Measures will be taken. However, with such means, as the motor speed decreases based on the frequency characteristics, the calculation accuracy of magnetic flux deteriorates, resulting in a decrease in the torque generated by the motor, and in particular, the starting torque decreases significantly, causing startup failure. There are drawbacks. In order to eliminate such drawbacks, the applicant has proposed that in an integrator equipped with a PI feedback circuit that constitutes a magnetic flux calculator, when a start command is issued and the speed of the motor is at a low level, the PI feedback circuit is removed from the integrator. is configured to operate as a pure integrator by cutting off the integrator, preventing the occurrence of phase errors in the integrator, performing highly accurate integral calculations, correctly controlling the control advance angle β of the inverter, and reducing torque at startup. Developed a starting method that can avoid the
No. 80275). FIG. 1 shows a control circuit for a commutatorless motor that implements the drive method previously proposed by the applicant. That is, in FIG.
indicates a synchronous motor, and this synchronous motor 10 converts AC power into direct current via a forward converter 12, and then converts it into an inverse converter 1 via a smoothing reactor 14 as appropriate.
6, and is configured to be driven by the AC power thus obtained. Speed control in the non-commutator motor configured as described above is performed by comparing the speed setting signal from the speed setting device 18 with the speed detection signal from the speed detection generator 20 directly connected to the synchronous motor 10. 22, then compares the output signal of the speed regulator 22 with the AC side input current detection signal of the forward converter 12, inputs it to the current regulator 24, and outputs the obtained output signal to the firing angle regulator 26. This is achieved by controlling the phase of the forward converter 12 through the converter 12. In addition, when starting a commutatorless motor, an induced voltage calculator 28 and a magnetic flux calculator 30 are provided, and the induced voltage calculator first calculates leakage reactance drop and resistance drop due to armature current from the terminal voltage of the motor 10. The induced voltage is determined by subtraction, and then the integrator induced voltage is integrally calculated in the magnetic flux calculator 30 to determine the magnetic flux.
Commutation control of the inverter 16 is performed via the pulse distributor 32 using the obtained magnetic flux waveform as a phase voltage (synchronization signal). In this case, the magnetic flux calculator 30 is constituted by an integrator to which a PI feedback circuit is added, as shown in FIG. 2, and the PI feedback circuit is detachably connected to the integrator via a switch 34. Furthermore, the switch 34 receives a start command signal and a speed detection generator 2.
0 (see FIG. 1) and a low speed level signal outputted via a comparator 38, respectively, and are configured to open and close according to the output signals of an AND circuit 36. By configuring the magnetic flux calculator 30 in this manner, when a start command is issued and the speed of the motor is at a low speed level, the magnetic speed calculator 30 operates as a pure integrator with the PI feedback circuit separated from the integrator. , it is possible to achieve stable and smooth control at startup as described above. In addition, in the starting method of the non-commutator motor configured as described above, when the motor rotates after starting and its rotational speed exceeds a predetermined low speed level set by the comparator 38, the PI feedback circuit and the integrator are activated. When connected, the magnetic flux calculator 30 operates as an integrator with a PI feedback circuit added.

[Problems to be solved by the invention]

By the way, when the magnetic flux calculator 30 switches, it is completely unknown what value the PI feedback amount is, and it changes every moment depending on the timing of switching the magnetic flux calculator 30. In particular, the output of the I feedback amplifier may be at a saturated output value due to the DC input offset. If the switching operation of the magnetic flux calculator 30 is performed in such a state, the output of the magnetic flux calculator 30 will be shocked due to a sudden change in input. This causes problems such as fluctuations in the torque of the electric motor, and in extreme cases, it becomes impossible to continue operating the electric motor. SUMMARY OF THE INVENTION Therefore, the present invention aims to achieve stable and smooth operation by preventing a decrease in torque at the time of starting and reliably preventing torque fluctuations after starting in the control of a non-commutator motor that does not require a position detector. The purpose of this invention is to provide a starting method for a commutatorless motor that is possible.

[Means to solve the problem]

In order to achieve such an objective, the present invention
A commutatorless motor that detects the induced voltage of the motor, calculates a magnetic flux waveform by integrating this induced voltage with a magnetic flux calculator, and uses this magnetic flux waveform as a synchronization signal for motor commutation. Connect the PI feedback circuit of the magnetic flux calculator and the integrator in a separable manner,
Under the AND condition of the start command and the low speed level of the motor, the PI feedback circuit is disconnected from the integrator to operate the magnetic flux calculator as a pure integrator, and the feedback capacitor of the I feedback amplifier in the PI feedback circuit is short-circuited. , when the motor speed exceeds the low speed level and the output signal of the magnetic flux calculator becomes zero, the PI
The feature is that the feedback circuit is connected to the integrator and the short circuit of the feedback capacitor of the I feedback amplifier is released.

【Example】

Next, an embodiment of a starting method for a commutatorless motor according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 3 shows a block diagram of a voltage model implementing the method of the present invention. That is, the system of the present invention is achieved by replacing the magnetic flux calculator 30 in the control circuit of the non-commutator motor shown in FIG. 1 with the magnetic flux calculator 30' having the configuration shown in FIG. 3. The magnetic flux calculator 30' shown in FIG. 3 is composed of an integrator to which a PI feedback circuit is added, and the PI feedback circuit is detachably connected to the integrator via a switch 40. The circuit that opens and closes this switch 40 converts the speed detection signal n from the speed detection generator 20 (see FIG. 1) into a low speed level signal "1" outputted via a comparator 42 and a start command signal "1". and a comparator 46 that outputs a "0" signal when the output signal Φ of the magnetic flux calculator 30' is 0, and the output signal of the AND circuit 44 and the output signal of the comparator 46 are input.
The output signal state is set to "1" by the output signal "1" of the NOR circuit 48 and the AND circuit 44.
The flip-flop 5 is set to the output signal state "0" by the output signal "1" of the NOR circuit 48.
0 and an AND circuit 52 which inputs the output signal of this flip-flop 50 and the activation command signal "1", and the switch 40 is opened and closed by the output signal of this AND circuit 52. Further, the output signal of the AND circuit 52 is passed through the NOT circuit 54 to open and close a switch 56 for forcibly holding the output of the I feedback amplifier at zero. By configuring the magnetic flux calculator 30' in this way, the output of the AND circuit 52 is "0" until a start command is input, and as the switch 40 opens and closes, the switch 56 also opens, and the magnetic flux calculator 30' is configured as an integrator to which a PI feedback circuit is added. At this point, the motor is in a stopped state, so the induced voltage is zero, so the magnetic flux calculator 3
The output signal Φ of 0' is also Φ=0. Next, when a start command is input, the start command signal “1” and the low level signal of the comparator 42 “1”
According to the AND condition, the output signal of the AND circuit 44 becomes "1", and as a result, the flip-flop 50 is set to the output signal state "1". As a result,
The switch 40 is opened by the output signal "1" of the AND circuit 52, the PI feedback circuit is disconnected, and the magnetic flux calculator 30' operates as a pure integrator. At this time, the output signal "1" of the AND circuit 52 closes the switch 56 via the NOT circuit 54, short-circuits the feedback capacitor of the I feedback amplifier, and forces the output of the I feedback amplifier to zero. to hold. After that, when the rotational speed of the electric motor increases and the speed detection signal n exceeds the low speed level of the comparator 42, the output signal of the comparator 42 becomes "0", and therefore the output signal of the AND circuit 44 also becomes "0".
becomes. On the other hand, an induced voltage E is also generated and changes sinusoidally, so the output signal Φ of the magnetic flux calculator 30' also changes sinusoidally in accordance with the induced voltage E. When this sine wave output signal Φ is supplied to the comparator 46, a "0" signal is output from the comparator 46 when Φ=0. therefore,
When Φ=0, the input condition of the NOR circuit 48 is
The output signal “0” of the AND circuit 44 and the output signal “0” of the comparator 46 are established, so the NOR
The output signal of the circuit 48 becomes "1". This causes the flip-flop 50 to have an output signal state of "0".
As a result, the switch 40 is closed by the output signal "0" of the AND circuit 52, and the magnetic flux calculator 30' operates as an integrator to which a PI feedback circuit is added. At the same time, the switch 56 is opened to release the short circuit of the feedback capacitor of the I feedback circuit, and as a result, the I feedback amplifier also returns to its original state. At this time, the PI return value becomes zero. In the embodiment shown in FIG. 3, the switch 34, AND circuit 36, and comparator 38 shown in FIG.
In addition to the corresponding switch 40, AND circuit 44, and comparator 42, a comparator 46, a NOR circuit, a flip-flop 50, and an AND circuit 52 are added to control the switch 40. When the low speed level signal "1" is given, as mentioned above, this circuit part is not involved.
Switch 40 is opened. On the other hand, when the rotation speed of the electric motor increases and the output signal of the comparator 42 becomes "0", the switch 40
In this embodiment, the timing of this circuit closing is determined by using the output signal Φ as the comparator 4.
6 and detecting the point in time when the sinusoidal output signal Φ becomes Φ=0. In other words, as described above, the NOR circuit 48 connects the comparator 4
2, that is, the output signal "0" of the AND circuit 44, and the output signal Φ=0, that is, the output signal "0" of the comparator 46, the flip-flop 50 is set to the output signal state "0". ”. This has the advantage that the switch 40 can be closed at Φ=0.

【Effect of the invention】

As explained above, according to the method according to the present invention, in the control of a non-commutator motor in which a position detector is omitted, the magnetic flux calculator that calculates the magnetic flux waveform that serves as a synchronization signal for motor commutation is activated only at low speeds. By always keeping the PI feedback amount at zero when switching to pure integral operation and switching to operate as an integrator with a PI feedback circuit when the motor speed exceeds a low speed level after the motor starts,
Shocks do not occur in the output of the magnetic flux calculator, and torque fluctuations in the motor can be prevented, thereby achieving stable and smooth operation of the motor.

[Brief explanation of the drawing]

Fig. 1 is a control circuit diagram of a non-commutator motor, Fig. 2 is a block wiring diagram showing an example of the configuration of a magnetic flux calculator of the control circuit shown in Fig. 1, and Fig. 3 is a magnetic flux calculation implementing the method of the present invention. FIG. 2 is a block wiring diagram showing one embodiment of the device. 10...Synchronous motor, 12...Forward converter, 14
...Smoothing reactor, 16...Inverse converter, 18...
... Speed setting device, 20 ... Speed detection generator, 22
...Speed regulator, 24...Current regulator, 26...
Firing angle adjuster, 28... Induced voltage calculator, 30,
30'...Magnetic flux calculator, 32...Pulse distributor,
34...Switch, 36...AND circuit, 38...
... Comparator, 40 ... Switch, 42 ... Comparator, 44 ... AND circuit, 46 ... Comparator, 48 ... NOR circuit, 50 ... Flip-flop, 52 ... AND circuit, 54 ... NOT
Circuit, 56... switch.

Claims (1)

[Claims] 1 Detects the induced voltage of the motor, calculates the magnetic flux waveform by integrating this induced voltage with a magnetic flux calculator, and uses this magnetic flux waveform as a synchronization signal for motor commutation.In a commutatorless motor that does not include a position detector. , the PI feedback circuit of the magnetic flux calculator and the integrator are connected in a detachable manner, and the PI feedback circuit is disconnected from the integrator under the AND condition of the start command and the low speed level of the motor, and the magnetic flux calculator is used as a pure integrator. At the same time, the feedback capacitor of the I feedback amplifier in the PI feedback circuit is short-circuited, and then, when the motor speed exceeds the low speed level and the output signal of the magnetic flux calculator becomes zero,
A starting method for a non-commutator motor characterized by connecting a PI feedback circuit to an integrator and releasing a short circuit in a feedback capacitor of an I feedback amplifier.