JPH09149677A - Dc brushless motor driver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To drive a motor at an optimum efficiency point for a load by a method wherein a ratio of a current detection value to an actual revolution is obtained to detect a load torque and an optimum phase shift is performed in accordance with the detected load torque. SOLUTION: The actual revolution of a rotor is calculated by a revolution calculating block 7a from the output of a rotor position detecting means 6. A load torque is calculated by a load torque calculating block 7b in which the output ratio between the rotor position detecting means 6 and a current detector 5. A phase shift value corresponding to the load torque is obtained by a phase shift value calculating block 7c. Then, when the logic calculation is performed in a logic calculating block 7d, the phase shift value is added and, as a result, the phase of the driving signal of a DC brushless motor is shifted, so that the motor is driven with the optimum phase for the load torque.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device for operating a DC brushless motor, which drives a load having a large variable width at a variable speed, at the maximum efficiency point for all loads.

[0002]

2. Description of the Related Art A DC brushless motor may have different current phase angles for obtaining optimum efficiency depending on load torque, as shown in FIG. In order to drive a motor having such characteristics with optimum efficiency for all loads, it is necessary to detect the load torque of the motor and shift the current phase accordingly.

Conventionally, as a device for simply detecting the load torque of a DC brushless motor and driving the DC brushless motor at the highest efficiency point against load fluctuations, for example, a configuration as shown in FIG. 3 has been adopted. In the figure, 1 is an AC power source, 2 is a converter unit for converting the AC power source 1 into a DC power source, 3 is an inverter unit including a semiconductor switch group, 4 is a DC brushless motor in which a rotor magnetic pole position sensor is omitted, and the inverter unit 3 It is driven by variable speed by supplying more AC power. Reference numeral 5 is a current detecting means for detecting an input current to the converter section 2, 6 is a rotor position detecting means for detecting a magnetic pole position of a magnet rotor of the DC brushless motor, and is composed of filter circuits 61 to 63 and a comparison circuit 64. It 7
Is a calculation means, a rotation speed calculation block that calculates the actual rotation speed of the rotor from the output of the rotor position detection means, and a motor that is a function of the actual rotation speed of the rotor and the input current value to the converter section. Of the load torque T, the phase shift amount calculation block for calculating the phase shift amount based on the load torque selected from the load torque table, and the output of the rotor position detecting means. It is composed of a logical operation block for performing a phase shift on the signal subjected to the logical operation based on the operation result of the phase shift amount operation block to generate a drive signal for the semiconductor switch group of the inverter section.

The operation of the above configuration will be described below. The phase voltage of the DC brushless motor 4 includes the induced voltage generated by the rotation. This induced voltage has rotor position information. The phase voltage including this induced voltage is input to the rotor position detecting means 6 and waveform-shaped by the filter circuits 61 to 63 and the comparison circuit 64. The output signals 6u, 6v, 6w are logically operated in the logical operation block of the operation means 7 as shown in FIG. 4, and the semiconductor switch groups U, V, W, X, Y, Z of the inverter section 3 are operated.
It is generated as a drive signal of. By driving the inverter unit 3 based on these, the rotating torque is continuously generated in the DC brushless motor 4, and the DC brushless motor 4 continues to rotate. Here, the output 6 of the rotor position detecting means 6
Since u, 6v, and 6w are signals synchronized with the actual rotation of the rotor, the actual rotation speed of the rotor is obtained by calculating these in the rotation speed calculation block 7a. The load torque corresponding to the actual rotation speed and the current value detected by the current detecting means 5 is selected from the load torque table 7f, and the corresponding phase shift amount is obtained by the phase shift amount calculation block 7c. When the logical operation is performed in the logical operation block 7d, this phase shift amount is added, and as a result, the drive signal phase of the DC brushless motor is shifted, so that the motor is driven in the optimum phase with respect to the load torque. The Rukoto.

[0005]

However, in the above configuration, the number of data of the load torque table to be stored in advance in the computing means 7 becomes huge and a large amount of memory capacity is required, and the data is one item. The problem is that it becomes difficult to deal with the design change of the motor etc. easily, and it is necessary to add new detection means to solve these problems, which makes the device complicated and large, and increases the cost. Had.

In view of the above problems, the present invention makes it possible to detect a motor load torque with high accuracy by a simple detecting means,
A DC brushless motor drive device capable of operating at an optimum efficiency point for all loads.

[0007]

In order to solve the above-mentioned problems, the present invention provides a converter section for converting an AC power supply into a direct current, current detecting means for detecting an input current of the converter section, and conversion by the converter section. The DC brushless motor without the sensor for detecting the magnetic pole position of the magnet rotor, and the magnetic pole position of the magnet rotor of the DC brushless motor. A rotor position detection means for detecting the rotation speed; and a calculation means, wherein the calculation means calculates the actual rotation speed of the rotor from the output of the rotor position detection means; A load torque calculation block that calculates a load torque from the output of the current detection means, and a phase shift amount based on the calculation result of the load torque calculation block. A phase shift amount calculation block for calculation and a signal obtained by logically calculating the output of the rotor position detection means are subjected to phase shift based on the calculation result of the phase shift amount calculation block to generate a drive signal for the semiconductor switch group of the inverter section. And a logical operation block.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention has
The load torque can be detected by obtaining the ratio between the detected current value and the actual rotation speed, and the optimum phase shift can be performed based on this to drive the DC brushless motor at the optimum efficiency point for all loads.

[0009]

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

FIG. 1 is a block diagram of a DC brushless motor drive device according to an embodiment of the present invention. In FIG. 1, 1 is an AC power source, 2 is a converter unit for converting the AC power source 1 into a DC power source, 3 is an inverter unit including a semiconductor switch group, and 4 is a DC brushless motor having no rotor magnetic pole position detection sensor. AC power is supplied from the unit 3 to drive at a variable speed. Reference numeral 5 is a current detecting means for detecting an input current to the converter section 2, 6 is a rotor position detecting means for detecting the magnetic pole position of the rotor of the DC brushless motor 4, and is provided by the filter circuits 61 to 63 and the comparison circuit 64. Composed. Reference numeral 7 denotes a calculation means, which is a rotation speed calculation block 7a for calculating the actual rotation speed of the rotor from the output of the rotor position detection means 6, and a load torque from the actual rotation speed of the rotor and the output of the current detection means 5. Load torque calculation block 7 for calculation
b, a phase shift amount calculation block 7c that calculates a phase shift amount based on the calculation result of the load torque calculation block 7b, and a signal obtained by logically calculating the output of the rotor position detecting means 6 to the phase shift amount calculation block. Logic operation block 7 for performing a phase shift based on the operation result of 7c to generate a drive signal for the semiconductor switch group of the inverter unit 3.
d.

The operation of the above configuration will be described with reference to FIG. However, the driving operation of the DC brushless motor in which the magnetic pole position sensor of the rotor is omitted, the relationship between the motor load torque and the optimum phase amount, and the output 6 of the rotor position detecting means 6
The procedure for calculating the rotation speed from u, 6v, and 6w and the method for performing the logical calculation are the same as those in the conventional example, and thus the description thereof is omitted.

Now, the voltage of the AC power supply 1 is V, and the current detection means 5
Is I, the actual rotation speed obtained by the rotation speed calculation block 7a is n, and the load torque of the DC brushless motor 4 is T, the electric power P _i supplied from the AC power supply 1 is P _i = V * I * Cos θ (cos θ is the power factor) On the other hand, the output P ₀ of the DC brushless motor 4 is T _o = n * T P ₀ = k * P _i (k is a constant) T = k * V * cos θ * I / n k * Since V * cos θ is a constant, T is proportional to I / n. Therefore, the load torque is obtained by calculating the ratio of the outputs of the rotor position detection circuit 6 and the current detection circuit 5 in the load torque calculation block 7b. The phase shift amount corresponding thereto is calculated by the phase shift amount calculation block 7c. When the logical operation is performed in the logical operation block 7d, this phase shift amount is added, and as a result, the drive signal phase of the DC brushless motor is shifted, so that the motor is driven at the optimum phase for the load torque. The Rukoto.

[0013]

As described above, according to the present invention, a converter section for converting an AC power supply into a direct current, a current detecting means for detecting an input current of the converter section, and a variable AC from the DC power source converted by the converter section. An inverter unit including a semiconductor switch group that generates a waveform, a DC brushless motor that does not include a sensor that detects the magnetic pole position of the magnet rotor, and a rotor position detection unit that detects the magnetic pole position of the magnet rotor of the DC brushless motor. And a calculation means, wherein the calculation means calculates the actual rotation speed of the rotor from the output of the rotor position detection means, and a load from the actual rotation speed of the rotor and the output of the current detection means. A load torque calculation block for calculating torque, and a phase shift amount calculation for calculating a phase shift amount based on the calculation result of the load torque calculation block. A lock and a logical operation block for generating a drive signal for the semiconductor switch group of the inverter section by subjecting a signal obtained by logically operating the output of the rotor position detecting means to a phase shift based on the operation result of the phase shift amount operation block. By doing so, the load torque of the motor can be accurately detected with a simple configuration, and the motor can be driven at the highest efficiency point for any load.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a DC brushless motor drive device of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between a load torque of a DC brushless motor and an optimum current phase amount.

FIG. 3 is a block diagram of a conventional DC brushless motor drive device that performs simple motor load detection.

FIG. 4 is a pattern diagram showing a relationship between an output signal of a rotor position detecting means and a logical operation result.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC power supply 2 Converter part 3 Inverter part 4 DC brushless motor 5 Current detection means 6 Rotor position detection means 7 Calculation means 61-63 Filter circuit 64 Comparison circuit 7a Rotation speed calculation block 7b Load torque calculation block 7c Phase shift amount calculation block 7d Logical operation block

Claims (1)

[Claims] 1. A converter section for converting an AC power supply into a DC power, a current detecting means for detecting an input current of the converter section, and a semiconductor switch group for generating a variable AC waveform from the DC power supply converted by the converter section. And a DC brushless motor in which a sensor for detecting the magnetic pole position of the magnet rotor is omitted, a rotor position detecting means for detecting the magnetic pole position of the magnet rotor of the DC brushless motor, and a computing means. The calculation means calculates the actual rotation speed of the rotor from the output of the rotor position detection means, and the load torque calculation block that calculates the load torque from the actual rotation speed of the rotor and the output of the current detection means. A phase shift amount calculation block for calculating a phase shift amount based on the calculation result of the load torque calculation block; and the rotor position. A DC brushless motor drive device including a logical operation block for generating a drive signal for a semiconductor switch group of the inverter section by subjecting a signal obtained by logically operating the output of the detection means to a phase shift based on the operation result of the phase shift amount operation block. .