JPS6019233B2 - Synchronous motor operation control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a system for reliably and quickly starting the synchronous motor by controlling the operation control of the synchronous motor, particularly by controlling the power applied to the synchronous motor by a semiconductor power converter. This invention relates to an operation control device.

An embodiment of the present invention shown in the drawings will be described below.

FIG. 1 shows an example of a starting circuit for a synchronous motor. In the figure, 1
is the busbar connected to the AC power supply, 2, 4, and 5 wires and disconnectors,
3 is a semiconductor power conversion device consisting of a forward converter and an inverse converter; 6 is a synchronous motor; a distributor that detects the position of the rotor and generates a signal according to the position; and a rotor that detects the rotation speed. The meter is directly connected or built-in. 7 is a constant speed signal generator, 8 is a start control device for the semiconductor power conversion device 3, and 9 is a signal converter that converts the above-mentioned distributor signal and rotation speed signal into a control level signal.

SI is a signal line for the AC power supply voltage, S2 is a signal line for the armature voltage of the synchronous motor, S3 is a signal line for the tree speed signal, S4 is a signal line for the AC power supply side current of the semiconductor power converter 3, and S5
is the signal line from the distributor and tachometer attached to the rotor of the synchronous motor 6, S6 is the output signal line from the signal converter 9,
S7 is a signal line that transmits a control signal to the semiconductor power conversion device 3. FIG. 3 shows a circuit configuration of the semiconductor power conversion device shown in FIG. 1. In the figure, 31 is a forward converter and a thyristor 31
1, 312, 313, 314, 315, and 316 are connected as shown in the figure.

32 is a DC IJ vector, 33 is an inverter, and is constructed by connecting thyristors 331, 332, 333, 334, 335, and 336 as shown in the figure.

81 is a control device that controls the forward converter 31 (as an example, controls the input current to 31 to be constant), and 82 is the same control device, which controls the thyristor in a constant phase relationship with respect to the induced voltage of the synchronous motor 6. 331, 332, 333, 334,
By igniting 335 and 336, DC power is converted to AC power and supplied to the synchronous power generator 6.

Since the inverse converter 33 performs commutation between phases using the reverse induced voltage of the synchronous motor, while the rotational speed of the synchronous motor 6 is small, the inverse converter 37 performs commutation between each phase (load transfer). As will be described later, the present invention is characterized in that the current in the DC circuit is forcibly reduced to zero by phase control of the forward converter 31 to cause commutation. A signal for this is applied from the control device 82 to the current intermittent signal generating circuit 811 through the signal line S61, and this intermittent signal is also applied to the control device 81 of the forward converter.

FIG. 4 shows a system diagram of the intermittent current starting control which is the main part of the present invention. In the figure, 811 is an intermittent signal generation circuit based on the signal of S61, 814 is an adder/subtractor, and S811 is one of the input signals of 814, which is a current reference signal. Reference numeral 812 constitutes a current control loop and is generally a transfer element for completely integral current control; 813 is a phase shifter that controls the phase of the forward converter 31; and S812 is a phase shifter that controls the phase of the forward converter 31 during the current intermittent period. The signal level to be narrowed down to SW1, SW2, SW
3 is a switch that opens and closes in synchronization with the intermittent signal from the intermittent signal generating circuit 811.

The control circuit 8101 constituted by 814, 812, 813, SW1, SW2, and SW3 is the control circuit 81 in the current intermittent start control region.

When starting the motor, the circuit breaker 5 is opened to turn 2 and 4 on, and the power is supplied from the AC bus 1 to the synchronous motor 6 by the semiconductor power converter 3 and its control device 8. is controlled to a synchronous speed using intermittent current start control, constant current acceleration control, foot speed control, uniform speed control, etc., and the bottle breaker 5 is closed by a signal from the bottle speed signal generator 7 that satisfies the conditions for synchronous closing. and the breaker 4 is opened. FIG. 2 illustrates the control mode during the startup operation described above. In the figure, nso is the rotation speed corresponding to the AC power frequency, nsl is the reference rotation speed signal used in the constant speed region, ship 2 is the rotation speed at which load commutation is possible for the inverter, and nM is the rotation speed. The rotation speed of the synchronous motor,
iM'The axis of the armature current is time. In this figure, period A is in the constant current control region until nM reaches ns2 (A'
period) is in the current intermittent start control state, and after NM reaches ns2 (period A'') it is controlled to be in the steady constant current acceleration control state.The synchronous motor is controlled in the constant current acceleration control state. When starting, the position of the rotor is detected by a distributor directly connected or built into the synchronous motor, and the detection signal controls the operation of the inverter, and the reverse induced voltage of the synchronous motor is used for commutation between phases. On the other hand, the synchronous motor is started by controlling the power supplied to the synchronous motor using the constant current control of the forward converter, but the back electromotive voltage of the synchronous motor is extremely small when starting the synchronous motor and at low speeds. This makes commutation between phases within the inverter difficult, making output power control very difficult.

Therefore, in such a case, the present invention intermittents the input of the inverse converter by controlling the phase of the forward converter in synchronization with the commutation between the phases of the inverse converter performed by the distributor. It is characterized by allowing commutation.

This current intermittent start control is performed to a speed at which the synchronous motor accelerates and its reverse induced voltage allows commutation between phases of the inverter (load commutation). In this case, in order to operate the power conversion device most efficiently, the current waveform needs to be a rectangular wave commensurate with the reference current value. Therefore, in the present invention, the current control transmission element of the current control loop of the forward converter is synchronized with the commutation between the phases of the reverse converter using an intermittent signal synchronized with the signal of the rotor and counterfeit detector connected to the synchronous motor. The above object is achieved by providing a circuit that suppresses the input signal of the phase shifter and, on the other hand, sets the input signal of the phase shifter to a level that narrows down the phase of the converter to the regenerative region. This will be explained in more detail with reference to each waveform shown in FIG.

The signal from the distributor 9 (FIG. 5A) connected to the electric motor 6 is sent to the logic control circuit 82 to determine the electrical angle 1 as shown in FIG. 5B.
A 20o pulse waveform is formed, which becomes the gate signal for each thyristor of the inverter 33. Here, forward converter 31
In order to synchronize the commutation of the inverter 33, the current is intermittent by passing the signal line Sbl through the intermittent signal generating circuit 811 to form a pulse waveform as shown in FIG. 5B.

An example of the circuit 811 is composed of a differentiating circuit that differentiates the waveform of B, and a monostable multipipelator that forms a predetermined pulse. The duration of this pulse is set in consideration of the decay time of the DC current, the turn-off time of the thyristor, and the margin time. The steady constant current acceleration period is S4,88
Constant current acceleration control is performed in constant current control loops 4, 812, 813, and 31, but during period A' in Fig. 2, inverter 3
8 if 3 thyristor arms perform phase-to-phase commutation.
The input signal of the current control transmission element 812 and the input signal from 812 to 813 are switched to SW1 and SW2 by the intermittent signal of 11.
The input signal of 813 is the signal of S812, which is provided to narrow down the phase of 31 by closing SW3, and the current of 31 is controlled by inverse converter operation. After the input current of the input current 33 becomes zero, commutation between the phases is performed. Here, the input/output of 812 is cut off during the current cutoff period, but since the transfer element used as a constant current control element is generally a completely integral type transfer element, the cutoff period is
The output voltage level of the transmission element is self-maintained,
The feature is that constant current control can be performed quickly and stably after the zero current period ends. FIG. 5C shows the input AC phase current waveform of the tortoise motor 6, where the rectangular wave input DC current "D" of the tortoise motor 6 is converted into AC by the constant current control.
After the intermittent current starting period ends, the intermittent starting switching circuit disconnects the intermittent signal circuit 811 to switch the operation mode to the steady constant current acceleration state.

This switching circuit is a circuit for comparing the signal of the speed detector directly connected to 6 and the speed reference signal, or a counting calculation circuit for converting the signal from the distributor into a frequency signal and the speed reference signal in the form of a constant frequency rectangular wave. It consists of The above explanation is for the case where the input signal of the current control transfer element is temporarily cut off, but the same characteristics can be obtained even if the input reference signal is cut off and the current feedback signal is left as is. be. Since the present invention is configured as described above, commutation between phases of the inverse converter can be easily and stably performed by phase control of the forward converter in the current intermittent start-up castle, so that the start-up control of the semiconductor power conversion device and This is effective in improving the stability of output power control.

[Brief explanation of the drawing]

FIG. 1 is an operation system diagram showing one embodiment of the present invention, FIG. 2 is an explanatory diagram showing a typical example of a synchronous motor operation control method, and FIG.
The figure shows an example of a semiconductor power conversion device, FIG. 4 is a diagram for explaining the main parts of the present invention, and FIG. 5 shows operational waveforms of each part in an embodiment of the present invention. In the figure, 1 is a bus connected to an AC power supply, 2, 4, and 5 are disconnectors, 3 is a semiconductor power converter, 6 is a synchronous motor,
Reference numeral 7 designates an alignment signal generator, 8 a start control device, and 9 a signal converter that converts a distributor signal and a rotation speed signal into a control level signal. Figure 2 Figure 4 Figure 1 Figure 3 Figure 5

Claims (1)

[Claims] 1 Supplying power to a synchronous motor through a semiconductor power conversion device having a forward converter that converts AC power to DC power, and an inverse converter that converts the DC power to variable frequency AC power, and the forward converter in which the phase of the inverter is controlled by a signal corresponding to the rotor position of the synchronous motor, and when the synchronous motor is started up and at low speed, commutation between the phases of the inverter and By providing a circuit that synchronously cuts off the input signal of the integral type current control transfer element of the forward converter and, on the other hand, sets the input signal of the phase shifter to a level that narrows down the phase of the forward converter to the regeneration region. ,
An operation control device for a synchronous motor, characterized in that the input current of the inverter is intermittent.