JPH02142383A - Brushless motor - Google Patents

Abstract

PURPOSE:To eliminate the influence of PWM by sampling an induced voltage generated in an armature winding and by computing a rotational position on the basis of the sampling and using the position for control. CONSTITUTION:Power 6 is rectified by a rectifier circuit 7, subjected to PMW by a switching circuit 2 and supplied to a motor 1. An induced voltage generated in each phase armature winding is sampled by a sampling circuit 3 and inputted to a microcomputer 5 via an A/D converter 4. On the other hand, the output voltage of the rectifier circuit 7 is inputted to the microcomputer 5 via an A/D converter 8. The microcomputer 5 computes a rotor position sensing point and the passing change-over point of the armature winding to use them for control. Even if the waveform of the induced voltage of the motor is subjected to PWM, the induced voltage is sampled and used for operation so as not to be subjected to the influence of PWM.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention detects the rotational position of a magnet rotor by using the induced voltage in the armature winding generated by the rotation of the magnet rotor, and This invention relates to a brushless motor that controls a group of switching elements.

<Prior art> In general, in brushless motors that use this type of induced voltage to control energization to the armature windings, the rotor is controlled by comparing the three-phase induced voltage and DC voltage. The location was being detected.

In the above-mentioned method, when the voltage applied to the motor has a PWM waveform, it is difficult to accurately detect the rotational position because there are places where the position of the rotor cannot be detected due to the influence of PWM. Furthermore, the stability of rotor position detection is lacking.

<Problems to be Solved by the Invention> As described above, in a brushless motor device, when the voltage applied to the motor is a PWM waveform, there are places where the position of the rotor cannot be detected due to the influence of PWM, and the position can be detected with high accuracy. It's difficult.

In view of the above-mentioned circumstances, an object of the present invention is to provide a brushless motor which detects the rotational position of a magnet rotor and controls a group of semiconductor switching elements, thereby solving the above-mentioned problems.

Means for Solving the Problems The first invention provides a brushless motor comprising a motor comprising a magnet rotor and a three-phase armature winding, and a semiconductor device comprising a plurality of semiconductor switching elements, The induced voltage generated in the armature winding is sampled, the microcomputer calculates the rotational position of the rotor using this sampling value, and the armature winding is energized based on the calculated rotational position. It is something to control.

Further, in the device, the induced voltage generated in the armature winding is sampled and held, and a trapezoidal voltage waveform obtained by adding a voltage varying in a sawtooth waveform to the held voltage is applied to the rotor. It is designed to be used for detecting the rotational position of.

Function> For the above configuration, first, the induced voltage of the armature winding is sampled, and the position of the rotor is calculated from this by a microcomputer.

In this case, even if the voltage applied to the motor is a PWM wave, the rotor position can be obtained by calculation without being influenced by PWM.

Additionally, it is equipped with a waveform shaping circuit that samples and holds this induced voltage and adds a sawtooth wave to create a trapezoidal induced voltage waveform, which can be used to detect the rotor position even when the motor applied voltage is a PWM waveform. The induced voltage waveform is made into a trapezoidal waveform to detect the rotor position.

<Example> The present invention will be described below based on the drawings of the example.

Figures 1, 2, and 3 relate to the first invention,
1 is a motor 1 consisting of a magnet rotor and a three-phase armature winding.
' and six semiconductor switching elements 2, the motor 1 is
The motor induced voltage value is paired with the sampling time by the sampling circuit 3 and the A/D converter 4 connected to the ' position, and is stored in the microcomputer 5.

On the other hand, electric! The DC voltage after rectification by the rectifier circuit 7 on the A6 side is sequentially taken into the microcomputer 5 via the A/D converter 8. Using these components, the rotor position detection point and the energization switching point of the armature winding are calculated in the microcomputer 5, and the energization of the winding is controlled.

Specifically, the calculation is performed as follows. That is,
In the induced voltage waveform in Fig. 2C, when the armature winding is energized at Tn, the induced voltage value and time data (t., vo) sampled at two points (a) and (b) (
1,4□+ ■n++) and the DC voltage value VD,
The rotor position detection point T0□ and the next armature winding energization switching point T'a41 can be calculated using the following two equations.

As described above, according to the present invention, even if the motor's induced voltage waveform is subjected to PWM, the induced voltage is sampled and calculated by the microcomputer 5, so that the rotor position detection point and the electric machine can be detected. The energization switching point of the child winding can be obtained without being affected by PWM.

However, (A) is the DC voltage after rectification, (B) is the motor induced voltage, (C) is the enlargement of section (1) of waveform (B), and (D
) is the motor induced voltage virtualized by the microcomputer, (a)
(b) and (c) indicate locations whose positions cannot be detected.

Next, FIG. 4 shows an embodiment of the second invention.

This will be explained based on FIG. First, the motor induced voltage shown in FIG. 5(A) is sampled and held by the sample-and-hold circuit 9 (FIG. 5(B)), and then the motor induced voltage shown in FIG. 5(C) generated by the sawtooth wave generating circuit 10 is sampled and held. As shown in FIG. 5 (D), the sawtooth wave is added by the adder circuit 11.
) is used to create the trapezoidal wave shown in the figure below. By comparing the magnitudes of this trapezoidal wave and the rectified DC voltage (FIG. 5(E)) in the comparison circuit 12, rotor position detection signals are obtained at the locations shown in FIG. 5(1) and (2).

Information such as the switching frequency is transferred from the microcomputer 5 to the sample/hold circuit 9, and sampling is performed. Further, information such as the switching frequency, motor rotation speed, switching element 2 conduction time, etc. is transferred from the microcomputer 5 to the sawtooth wave generation channel 10, and in synchronization with the switching frequency, a sawtooth wave is generated according to the operating status of the motor. .

However, (A) is the motor induced voltage, (B) is the sample-and-hold circuit output, (C) is the sawtooth wave generation circuit output, (
D) is the adder circuit output, (E) is the DC voltage after rectification, (
1) (2) is the rotor position detection location, (a) (b) (c)
indicates a location whose position cannot be detected.

As described above, in the present invention, the rotor position detection point can be obtained without being influenced by PWM by shaping the induced voltage waveform of the PWM waveform into a trapezoidal wave and then comparing the magnitude with the DC voltage.

<Effects of the Invention> As described above, the brushless motor of the present invention uses a sampling circuit to detect the induced voltage in the armature winding.

A/D converter, microcomputer, etc. use the sampled values to calculate the rotor position using the microcomputer, or sample and
PWM
When detecting the rotor position using waveform motor induced voltage, it is possible to eliminate the influence of locations where the position cannot be detected due to PWM, and the rotor position can be detected with high accuracy. This has the effect of stabilizing child position detection.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a control block diagram of the first invention, FIG. 2 is a diagram showing voltage waveforms of each part of the same, FIG. 3 is a flowchart of the same calculation, and FIG. is a control block diagram of the second invention, and FIG. 5 is a diagram showing voltage waveforms at various parts. DESCRIPTION OF SYMBOLS 1... Semiconductor device, 1'... Motor, 2... Semiconductor switching element, 3... Sampling circuit, 4...
... A/D converter, 5... Microcomputer, 9... Sample/hold circuit, 10... Sawtooth wave generation circuit, 11... Adder circuit, 12... Comparison circuit. Figure 1 Shoulder Figure 2

Claims (2)

[Claims] 1. In a brushless motor consisting of a motor consisting of a magnet rotor and a three-phase armature winding, and a semiconductor device consisting of a plurality of semiconductor switching elements, the induced voltage generated in the armature winding is sampled. A brushless motor characterized in that the rotational position of the rotor is calculated by a microcomputer using the value, and the energization to the armature winding is controlled based on the calculated rotational position. 2. In the brushless motor device, the induced voltage generated in the armature winding is sampled and held, and a trapezoidal voltage waveform obtained by adding a voltage that changes in a sawtooth waveform to this held voltage is used to detect the rotational position of the rotor. A brushless motor characterized by: