JPH01103190A - Controller for synchronous motor - Google Patents

Abstract

PURPOSE:To achieve smooth operation from start to high speed operation and to carry out speed control in the range from high speed to low speed, by comparing a position detecting signal fed from a Hall sensor with a phase control sensor. CONSTITUTION:A poly-phase rectangular wave oscillator 16 controls the oscillation frequency of a poly-phase rectangular wave according to a frequency control signal fed from a frequency regulating circuit 14. A power conduction phase regulating circuit 20 outputs a phase control signal according to the frequency control signal. A power conduction phase operating circuit 18 controls the phase of the poly-phase rectangular wave according to the phase control signal. A Hall sensor for detecting the position of a rotor is arranged on a stator box, and the power conduction phase operating circuit 18 compares a position detecting signal fed from the Hall sensor with the phase control signal fed from the power conduction regulating circuit 20 and carries out current control accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a synchronous motor control device, and more particularly to a synchronous motor control device suitable for speed adjustment with an inexpensive and simple configuration. It is.

(Prior Art) A synchronous motor does not generate rotational torque at speeds other than synchronous speed, and the starting torque is almost zero. Therefore, in order to start the synchronous motor, a self-starting method with eight starting (braking) wires or an auxiliary motor for starting is required.

Further, a synchronous motor is a completely constant speed motor that rotates at a synchronous speed, and although it is difficult to control the speed -Jm, speed control can be performed by changing the synchronous speed itself. In other words, the question is whether to change the frequency of the power supply or change the number of poles.

A method of varying the power supply frequency is possible if the electric motor is operated by a dedicated generator. In the method of changing the number of poles, the number of poles of the armature winding and the number of fields must be changed at the same time.

However, the above-mentioned conventional synchronous motor is difficult to start and requires a special starting device, resulting in a complicated and expensive configuration. In addition, although the load current of a synchronous motor is relatively small at high speeds, the load current increases as the speed decreases, so the speed 3I!
! - It is difficult to do. Furthermore, synchronous motors have conventionally used permanent magnets in the rotor, and in order to make motors more compact and efficient, powerful magnets were needed, but rare earth magnets are used for this purpose. Extremely expensive.

In order to solve these various problems, the present applicant previously proposed a ``synchronous motor control device'' (see specification of patent application No. 1999). This synchronous motor control device automatically calculates and controls the energization phase by comparing the output of the three-phase rectangular wave oscillation circuit controlled by frequency control No. 13 with the phase control signal in the energization phase calculation circuit. This controls the starting of the synchronous motor. In this energization phase calculation circuit, the current value is differentiated to cut unnecessary current input to torque, but the rotor magnet position changes depending on the load.
In practice, there were cases in which accurate control was not possible because the system was delayed or advanced.

(Purpose) The purpose of the present invention is to correct the problems of the previous technology, to enable a synchronous motor to automatically operate smoothly from startup to high-speed operation using a simple startup device, and to enable smooth operation of a synchronous motor from high-speed to high-speed operation. An object of the present invention is to provide a synchronous motor control device that enables speed control in a range up to low speeds.

(Means for Solving the Problems) In order to solve the above problems, the synchronous motor control device of the present invention provides a multi-phase synchronous motor and an oscillation frequency that is linearly adjusted from zero in response to turning on a power switch. a frequency adjustment circuit that outputs a frequency control signal instructing the frequency to increase to a predetermined high frequency; a polyphase rectangular wave oscillation circuit that controls the oscillation frequency of the polyphase rectangular wave according to the frequency control signal; and the frequency adjustment circuit. an energization phase adjustment circuit that outputs a phase control signal in accordance with a signal related to the frequency control signal of the circuit; and an energization that controls the phase of the polyphase rectangular wave oscillation frequency of the multiphase rectangular wave oscillation circuit in accordance with the phase control signal. A synchronous motor control device comprising a phase calculation circuit and a drive circuit that amplifies an output multiphase rectangular wave signal of the energization phase calculation circuit and supplies it to a field winding of the motor, A Hall sensor for detecting the position of the rotor is provided on the primary side of the PT, and the energization phase calculation circuit compares and calculates the position detection signal from the Hall sensor and the phase control signal.

(Function) In the present invention, the energization phase calculation circuit performs a comparison operation between the position detection signal from the Hall sensor and the phase control signal, thereby controlling the current, which was insufficient only by differentiating the current value. This is done accurately.

This makes automatic start control and wide range speed control of the synchronous motor more reliable.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a block diagram of a synchronous motor control device to which the present invention is applied.

In FIG. 2, reference numeral 2 denotes a polyphase synchronous motor, and here it is assumed to be, for example, a three-phase synchronous motor. 4 is a high frequency oscillation circuit, and the oscillation frequency is several tens of KHz.

The oscillation frequency is set to a high frequency in order to efficiently supply exciting current to the armature of the motor with a small device. Further, this oscillation signal is supplied to the frequency adjustment circuit 14 and used as a starting signal 48 for the motor, and the phase inversion amplifier circuit 6
is supplied to obtain positive phase and negative phase signals. The output signal of the amplifier circuit 6 is amplified by the excitation power amplifier circuit 8, and excites the primary side of the rotary transformer 10. The rotary transformer 10 is configured with a high frequency transformer in order to supply the high frequency amplified by the excitation power amplification circuit 8 to the rotor of the electric motor without contact and with high efficiency.
The primary side is fixed, and the secondary side is attached to the main shaft of the motor and rotates together with the rotor.

A high frequency signal supplied from the secondary side of the rotary transformer 10 is rectified by a DC converter 12, that is, a full wave rectifier, and is supplied to the armature coil of the rotor.

16 indicates a three-phase rectangular wave oscillation circuit. Conventional three-phase rectangular wave oscillation circuits have complicated circuit configurations because they oscillate continuous rectangular waves using a ring counter oscillator or the like and combine the waveforms to form three-phase rectangular waves. The oscillation circuit used in the present invention is constructed with an extremely small number of elements.

14 is a frequency adjustment circuit for controlling the oscillation frequency of the three-phase rectangular wave oscillation circuit 16. In other words, the output from the high frequency oscillation circuit 4 (in response to No. 2, the three-phase rectangular wave oscillation circuit 1
In addition to controlling the oscillation frequency of 6 and changing it from a low frequency to a high frequency when starting the motor, it is also possible to change the frequency of the stable three-phase rectangular wave over a wide range in order to control the rotation speed of the motor over a wide range. .

Energizing phase J! The I adjustment circuit 20 responds to the output signal of the frequency a adjustment circuit 14 and supplies a signal for controlling the phase of the output rectangular wave of the three-phase rectangular wave oscillation circuit 16 to the energization phase calculation circuit 18 to adjust the phase of the three-phase rectangular wave. It is something to control.

Conventionally, in synchronous motors, even if the load torque is the same, the load current is low to a certain extent at high speed rotation, and it is possible to sell some efficiency, but as the speed decreases, the load current increases at an accelerating rate, making it difficult to withstand use. It disappears. Therefore, continuous speed adjustment of synchronous motors has been difficult. Therefore, in this device, the energization phase adjustment circuit 20 controls the phase of the three-phase rectangular wave so that only the current necessary for generating rotational torque flows and the current not necessary for generating low rotational torque is cut off.

The energization phase calculation circuit 18 controls the phase of the three-phase rectangular wave signal in accordance with the phase control signal from the energization phase:A difference circuit 20 so as to increase the efficiency of the motor, and supplies the control signal to the buffer amplifier circuit 22.

The buffer amplifier circuit 22 alleviates the risk that stable phase control will not be performed when there is an impulsive change in the load when the motor drive circuit 24 and the energization phase calculation circuit 18 are directly connected. This is an amplifier circuit for Therefore, a common inverter amplifier is used in this circuit.

FIG. 1 is a configuration diagram of an energization phase calculation circuit showing an embodiment of the present invention. This is a detailed configuration example of the energization phase calculation circuit shown in Fig. 2, and is an improvement of the energization phase control calculation circuit shown in Fig. 2 of the previously proposed patent application No. 1 (hereinafter referred to as the prior application). .

In FIG. 1, 101 to 116 are operational amplifiers, 117
is FET, 118.119 is SBS.

200 to 208 are circuits that perform the following, and TR1 to TR7 are transistors R1 to R6.
2 is a resistor, DI to D13 are diodes, ZDI is a Zener diode, CI is a capacitor, and C2 to C3 are capacitors. The operation of this circuit will be explained below.

In the above-mentioned prior application, the output rectangular wave of the three-phase rectangular wave oscillation circuit is differentiated by a differentiator to cut unnecessary (excessive) current input to torque. The maximum value of the differential waveform is constant with respect to frequency, and the final peak value of each differential wave decreases as the frequency decreases. However, since the relative position between the rotor and the stator changes depending on the load, it is insufficient to simply control the oscillation frequency on a straight line of the staircase waveform using the frequency control signal. That is, at some point, too much load current may flow.

Therefore, in this embodiment, a Hall sensor is provided on the PT primary side of the stator box of the synchronous motor (not shown), the Hall sensor detects the relative position between the rotor and the stator, and this position detection signal is sent to the resistor R1. By inputting the signal to the operational amplifiers 101 to 103 via R6 and performing phase calculation control, more reliable speed control from low speed to high speed is possible.

In the case of a three-phase system, three Hall sensors are provided, and the number and position of the Hall sensors are changed depending on the number of phases (for example, two-phase, four-phase, etc.).

In this way, in this embodiment, a Hall sensor is provided to detect the position of the rotor, and phase calculation control is performed based on the position detection signal, so that more accurate operation control can be achieved than by the current value differentiation using the differentiator of the previous application.

(Effects of the Invention) As explained above, according to the present invention, current control is performed by comparing and calculating the position detection signal from the Hall sensor and the phase control signal, so a simple starting device can be used. The synchronous motor can be automatically operated smoothly from startup to high-speed operation, and high-performance speed control can be performed in the range from high speed to low speed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a phase calculation circuit showing an embodiment of the present invention, and FIG. 2 is a block diagram of a synchronous motor to which the present invention is applied. 18... Energization phase calculation circuit, 101-116... Operational amplifier, 117... FET 118.119... SBS. 200~208... Circuit, TRI~
TR7...Transistor, R1-R62...Resistor, D1-DI3...Diode, ZDI...Zener diode, C1...Capacitor, 02-C3...Capacitor. Patent applicant Dekidenki Co., Ltd.

Claims (1)

[Claims] A multiphase synchronous motor; a frequency adjustment circuit that outputs a frequency control signal instructing to linearly increase the oscillation frequency from zero to a predetermined high frequency in response to turning on a power switch; a polyphase rectangular wave oscillation circuit whose oscillation frequency of a polyphase rectangular wave is controlled in accordance with the frequency control signal; and an energization phase adjustment circuit which outputs a phase control signal in accordance with a signal related to the frequency control signal of the frequency adjustment circuit. and an energization phase calculation circuit that controls the phase of the polyphase rectangular wave oscillation frequency of the polyphase rectangular wave oscillation circuit in accordance with the phase control signal, and amplifying the output polyphase rectangular wave signal of the energization phase calculation circuit to A synchronous motor control device comprising a drive circuit for applying a field winding to a field winding of an electric motor, wherein a Hall sensor for detecting the position of the rotor is provided on the PT primary side of the stator box of the multiphase motor, and the energization phase calculation circuit comprises: A synchronous motor control device characterized in that a position detection signal from the Hall sensor and the phase control signal are compared and calculated.