JP5409332B2 - DC motor control device and ventilation device - Google Patents

Description

  The present invention relates to a DC motor control device and a ventilating device that performs air volume control of a ventilation fan using the DC motor control device.

  In the conventional ventilator, the air volume control of the ventilation fan, the relationship between the fan speed and the air volume corresponding to the pressure loss of the air path is measured in advance by experiment, and it is prepared in the controller as a data table, What is implemented by a method in which a controller switches a voltage applied to a DC motor that rotates a fan according to a set air volume is known. In this case, as a configuration of the ventilation fan, a configuration in which a DC motor and a dedicated drive circuit for driving the DC motor are mounted, or a configuration in which a DC motor having a dedicated drive circuit is mounted is employed.

  In a ventilator that employs such an air volume control method, it is necessary to measure the relationship between the fan speed and the air volume for each ventilation fan, which requires an enormous amount of test time and increases costs. ing. In addition, each ventilation fan requires a DC motor and a dedicated drive circuit for driving it, or a DC motor with a built-in dedicated drive circuit, so it is difficult to standardize key parts, which also increases costs. It is a factor.

  Therefore, for example, Patent Document 1 proposes a DC motor control method that solves the above-described two problems. That is, in Patent Document 1, a DC motor is driven at a constant voltage, and the load torque of the DC motor is based on a drive current supplied to the DC motor, a motor rotation speed, and a command load drive current value for obtaining a set air volume. An air volume control method has been proposed in which the change in the load is detected and the drive voltage is controlled in accordance with the change in the load torque to maintain the motor-generated torque at a value commensurate with the command load drive current value.

JP 2005-273547 A

  By the way, this invention intends realization of the ventilation apparatus which can perform constant air volume control of a ventilation fan using the proportionality relationship between the rotation speed of a DC motor and torque current. For this purpose, it is possible to realize a DC motor control device having a function that the conventional drive circuit described above does not have, that is, a function that can calculate torque current information and output it to the controller of the ventilator in the process of driving the DC motor. is necessary. Then, in particular, if the DC motor is configured to have a built-in DC motor control device, a DC motor that can be used universally for a ventilation fan of a ventilator that performs constant air flow control can be obtained, thereby solving the above two problems. be able to.

  In this case, the torque current information is obtained from the detected motor current. When the detected motor current includes the consumption current of the DC motor control device, the controller calculates the error current for each DC motor control device to be used. Excluding operations are required. Therefore, in order to eliminate the need for a dedicated controller that performs control in accordance with the characteristics of the DC motor control device, the DC motor control device of the present invention needs to be able to output torque current information that does not include an error current to the controller. It is.

  The present invention has been made in view of the above, and obtains a DC motor control device capable of outputting highly accurate torque current information, and a ventilation device capable of accurately controlling a constant air flow rate of a ventilation fan using the DC motor control device. For the purpose.

  In order to achieve the above-described object, a DC motor control device according to the present invention includes an inverter circuit that switches a DC voltage based on a PWM drive signal and outputs a drive voltage to the DC motor, and a bus in the switching circuit of the inverter circuit. A motor current detection circuit that detects a current as a motor current, generates and outputs the PWM drive signal according to an external speed command, and divides the detected motor current by a ratio of the drive voltage to the DC voltage to generate a torque current And a control circuit for outputting the obtained torque current information and a rotation pulse signal indicating the motor rotation speed to the outside.

  According to the present invention, the DC motor control device can output highly accurate torque current information. Therefore, if used for controlling the DC motor mounted on the ventilation fan of the ventilator, the controller of the ventilator can accurately obtain torque current information necessary for controlling the constant air flow of the ventilator. If this DC motor control device is built in the DC motor, there is an effect that a DC motor that can be used for a general purpose in a ventilation fan of a ventilation device that performs constant air flow control is obtained.

FIG. 1 is a block diagram illustrating a configuration example of a ventilator including a DC motor control device according to an embodiment of the present invention. FIG. 2 is a diagram for explaining an example of torque current information output to the controller by the control circuit shown in FIG. FIG. 3 is a diagram illustrating an example of a rotation pulse signal output from the control circuit shown in FIG. 1 to the controller. FIG. 4 is a flowchart illustrating a procedure for generating a motor current in which the control circuit shown in FIG. 1 cancels the offset voltage of the amplifier circuit.

  Embodiments of a DC motor control device and a ventilation device according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment.

  FIG. 1 is a block diagram illustrating a configuration example of a ventilator including a DC motor control device according to an embodiment of the present invention. In FIG. 1, the ventilation device 1 includes a controller 2, a power supply circuit 3, and a ventilation fan 4. The ventilation fan 4 is equipped with a fan 5, a DC motor 6 that rotates the fan 5, and a DC motor control device 7 that controls the DC motor 6. In this embodiment, the DC motor control device 7 is built in the DC motor 6.

  In this embodiment, the power supply circuit 3 receives AC 100 V (not shown), and converts and generates DC voltages of DC 140 V, DC 15 V, and DC 5 V from the AC 100 V. DC140V is output between the positive terminal a and the negative terminal d. DC15V is output between the positive terminal b and the negative terminal d. DC5V is output between the positive terminal c and the negative terminal d. In the power supply circuit in the ventilator used in the AC200V system, DC280V is converted and generated instead of DC140V.

  The DC motor control device 7 includes a control circuit 10, an inverter circuit 11, and a shunt resistor 12 and an amplifier circuit 13 that constitute a current detection circuit on a circuit board. On the circuit board, power terminals 14a, 14b, 14c, 14d for the power circuit 3 and signal terminals 15a, 15b, 15c for the controller 2 are provided.

  A power supply terminal 14 d to which the negative electrode terminal d of the power supply circuit 3 is connected is connected to a circuit ground GND of a circuit board on which the DC motor control device 7 is mounted. The conversion target power supply of the inverter circuit 11 is a direct-current voltage (DC 140 V) supplied from the positive terminal a of the power supply circuit 3 to the power supply terminal 14 a. The operating power supply of the control circuit 10 is a DC voltage (DC15V) supplied from the positive terminal b of the power supply circuit 3 to the power supply terminal 14b. The operating power supply of the amplifier circuit 13 is a DC voltage (DC5V) supplied from the positive terminal c of the power supply circuit 3 to the power supply terminal 14c. The power supply terminal 14a is also connected to the control circuit 10. This is because the DC voltage (DC 140 V) applied to the inverter circuit 11 is used for the generation calculation of torque current information.

  Between the controller 2 and the control circuit 10, the controller 2 outputs a speed command to the control circuit 10 via the signal terminal 15a. The controller 2 takes in the rotation pulse signal and torque current information generated by the control circuit 10 via the signal terminal 15b and the signal terminal 15c, respectively.

  The inverter circuit 11 to which the PWM drive signal is input from the control circuit 10 shows only the switching circuit 11a, but the positive bus P of the switching circuit 11a is connected to the power supply terminal 14a, and the negative bus N is the shunt resistor 12. Is connected to the circuit ground GND.

  The connection end of the negative bus N of the switching circuit 11 a and the shunt resistor 12 is connected to the input terminal of the amplifier circuit 13, and the output terminal of the amplifier circuit 13 is connected to the motor current monitoring port of the control circuit 10.

  In the above configuration, the control circuit 10 generates a PWM drive signal in accordance with a speed command input from the controller 2 via the signal terminal 15 a and outputs the PWM drive signal to the inverter circuit 11. Thereby, in the inverter circuit 11, the switching circuit 11 a is driven, and a three-phase AC voltage is generated from the applied DC voltage (DC 140 V) and supplied to the DC motor 6. A current obtained by averaging three-phase motor currents supplied to the DC motor 6 flows through the negative electrode bus N of the switching circuit 11a. The averaged motor current is detected (voltage conversion) by the shunt resistor 12, amplified by the amplification circuit 13 with a predetermined gain, and input to the control circuit 10. In this way, the control circuit 10 is supplied with a voltage signal indicating a pure motor current that does not include DC15V or DC5V consumption current (that is, error current).

  When a detection voltage corresponding to the motor current detected from the amplifier circuit 13 is input, the control circuit 10 performs an operation related to this embodiment. That is, the control circuit 10 generates torque current information of the DC motor 6 and a rotation pulse signal indicating the rotation speed, respectively, using the output voltage of the amplifier circuit 13 and the DC voltage (DC 140 V) applied to the inverter 11. And output to the controller 2 through the signal terminals 15b and 15c.

  Hereinafter, with reference to FIG. 2 to FIG. 4, the operation related to this embodiment performed by the control circuit 10 will be specifically described. FIG. 2 is a diagram for explaining an example of torque current information output to the controller by the control circuit shown in FIG. FIG. 3 is a diagram illustrating an example of a rotation pulse signal output from the control circuit shown in FIG. 1 to the controller. FIG. 4 is a flowchart illustrating a procedure for generating a motor current in which the control circuit shown in FIG. 1 cancels the offset voltage of the amplifier circuit.

<Generation operation of torque current information output to controller 2>
The torque current is a current that flows in the DC motor 6 in the ON region of the duty of the PWM drive signal, that is, a peak current, and has a proportional relationship with the rotational speed of the DC motor 6. Therefore, the control circuit 10 first extracts the motor drive voltage corresponding to the speed command input from the controller 2 from the relationship table between the speed command and the corresponding drive voltage to the DC motor 6, and converts the extracted motor drive voltage to the inverter. 11 is divided by the direct current voltage (DC 140 V) applied to 11. That is, the ratio of the drive voltage actually applied to the DC motor 6 to the DC voltage (DC 140 V) supplied to the inverter 11 is obtained. Then, the motor current indicated by the output voltage of the amplifier circuit 13 is divided by the obtained ratio to obtain the torque current.

As a method for outputting the obtained torque current to the controller 2, for example, two methods are conceivable. Torque current information refers to a signal generated by either of these two methods.
In the first method, since the obtained torque current value is a digital value, it is converted into an analog voltage assigned within a predetermined voltage range and output, for example, as shown in FIG. In FIG. 2, the vertical axis represents torque current, and the horizontal axis represents D / A output. FIG. 2 shows an example in which an analog voltage of 0V to 5V is assigned to a torque current of 0A to 1A. Note that the upper limit of the torque current value is set in accordance with the region actually used.
The second method is a method of outputting the torque current value as the number of pulses within a certain period instead of the analog voltage output.

  As a result, the controller 2 can obtain the torque current information necessary for performing the constant air volume control with high accuracy. Therefore, the controller 2 can control any type of DC motor control device 7 based on the relationship between the torque current obtained from the DC motor control device 7 and the rotational speed. There is no need to use it separately for each model, and standardization is possible.

  Further, since the DC motor control device 7 can output accurate torque current information, it becomes easy to use from the controller 2 side as described above, leading to standardization of the DC motor control device 7 itself. Furthermore, by incorporating the DC motor control device 7 in the DC motor 6, a DC motor that can be used for a general purpose fan can be obtained, and the ventilation fan 4 can be standardized.

<Generation operation of rotation pulse signal output to controller 2>
The controller 2 uses the input rotation pulse signal as basic data when generating a speed command. In this embodiment, it is intended that the controller 2 can generate a speed command with a simple configuration and perform air volume control without depending on an expensive microcomputer.

  If the rotation pulse signal output to the controller 2 is fixed at a duty of 50% as in the prior art and the cycle is varied according to the rotation speed, the pulse signals with a fixed duty of 50% are all integrated at the same voltage level. Therefore, the controller 2 cannot integrate the pulse signal and perform analog processing, and digital processing is performed using an expensive microcomputer.

  Therefore, in this embodiment, in order to enable the controller 2 to generate a speed command by simple analog processing, the control circuit 10 sets the duty of the rotation pulse signal to be output to the controller 2 without changing the cycle. It is made to change according to.

  The control circuit 10 includes a relationship table between the torque current and the rotational speed of the DC motor 6 that is proportional to the torque current. As described above, when the torque current is detected by the shunt resistor 12 and the detection voltage is input from the amplifier circuit 13, the control circuit 10 uses the torque current corresponding to the detection voltage as a search key to search the DC from the relation table. The rotational speed of the motor 6 is taken out and the speed range is determined. For example, as shown in FIG. 3, (1) a rotation pulse signal with a duty of 20% is generated and output at low speed, and (2) a rotation pulse signal with a duty of 50% is generated and output at medium speed, (2 ) At high speed, a rotation pulse signal with a duty of 80% is generated and output. The output to the controller 2 can be synchronized with the duty of the PWM drive signal.

  Then, in the controller 2, for example, the rotation speed signal (analog signal) obtained by integrating the input rotation pulse output and the input torque current signal (analog signal) are configured as an error amplifier, and the proportionally integrated signal is set as a speed command. The configuration of outputting to the control circuit 10 can be taken.

  In this way, the rotation pulse signal output to the controller 2 is made variable according to the rotation speed without changing the cycle, so that the controller 2 can perform simple analog processing without using an expensive microcomputer. Can control the constant air flow.

<Operation for Generating Motor Current Canceling Offset Voltage of Amplifier Circuit 13>
The shunt resistor 12 has a low resistance value in order to reduce resistance loss, and the voltage value generated at both ends is extremely small. Therefore, when the converted voltage of the shunt resistor 12 is input to the control circuit 10 as it is, the determination accuracy of the motor current in the control circuit 10 is deteriorated. The amplifier circuit 13 is provided in the control circuit 10 in order to increase the accuracy of determining the motor current.

  However, since the amplifier circuit 13 is configured by a so-called OP amplifier, the output voltage of the amplifier circuit 13 includes an offset voltage. This offset voltage causes an error in the air volume control. Therefore, in this embodiment, the offset voltage of the amplifier circuit 13 is canceled so that a pure motor current can be obtained. However, since the offset voltage differs for each product, the offset voltage determined by the product specifications of the OP amplifier is not used. The offset voltage of the amplifier circuit 13 actually used is canceled by the procedure shown in FIG. 4, for example, so that a pure motor current can be obtained. Note that the offset voltage canceling process is not particularly limited as to whether it is performed only for the first time when the power is turned on or whether it is sequentially performed every predetermined time.

  In FIG. 4, the control circuit 10 stops outputting the PMW drive signal to the inverter circuit 11 and puts the DC motor 6 into the operation stop state (ST1), takes in the output voltage of the amplifier circuit 13, and offsets the voltage value. The voltage A is set (ST2). Thereafter, the control circuit 10 starts outputting a PMW drive signal to the inverter circuit 11 and puts the DC motor 6 into an operating state (ST3). When the DC motor 6 starts operation, the control circuit 10 uses the motor current indicated by the value (detected motor current conversion voltage value) obtained by subtracting the offset voltage A from the output voltage of the amplifier circuit 13 (ST4).

  As described above, it is possible to detect the motor current with high accuracy by absorbing the error of the amplifier circuit, so that more accurate torque current information can be output to the controller 2.

  In FIG. 1, the current detection circuit is configured using the shunt resistor 12, but the current detection circuit may be configured using a current transformer. In this case, the current flowing through the secondary winding of the current transformer is voltage-converted and input to the amplifier circuit. The DC motor control device 7 can also employ a configuration in which a power supply circuit that generates a step-down voltage from DC140V to DC15V or DC5V is mounted. According to this configuration, the external wiring can be simplified. It goes without saying that the DC 15V or DC 5V control power supply generated by the step-down generation needs to generate an appropriate voltage value according to the rating of the component to be used.

  As described above, the DC motor control device according to the present invention is a DC motor control device used in a ventilation device that can perform constant air volume control of a ventilation fan by utilizing the proportional relationship between the rotational speed of the DC motor and the torque current. Useful.

DESCRIPTION OF SYMBOLS 1 Ventilation device 2 Controller 3 Power supply circuit 4 Ventilation fan 5 Fan 6 DC motor 7 DC motor control device 10 Control circuit 11 Inverter circuit 11a Switching circuit 12 Shunt resistor 13 Amplifier circuit

Claims (7)

An inverter circuit that switches a DC voltage based on a PWM drive signal and outputs a drive voltage to a DC motor;
A motor current detection circuit for detecting a bus current in the switching circuit of the inverter circuit as a motor current;
The PWM drive signal is generated and output in accordance with a speed command from an external controller , the detected motor current is divided by a ratio of the drive voltage to the DC voltage, a torque current is obtained, and the obtained torque current information and A control circuit for outputting a rotation pulse signal indicating the motor rotation speed to the outside ;
Equipped with a,
The control circuit outputs a PWM drive signal to the inverter circuit, outputs the torque current information and the rotation pulse signal to an external controller,
The control circuit determines which of the multi-stage speed range the motor rotation speed belongs to,
The control circuit changes the duty of the rotation pulse signal to a duty corresponding to a speed range to which the motor rotation speed belongs .   The motor current detection circuit includes a resistor provided between a negative bus in the switching circuit of the inverter circuit and a circuit ground, and an amplifier circuit that amplifies a conversion voltage at the resistor with a predetermined gain, and the control The DC motor control device according to claim 1, wherein the circuit calculates the torque current based on an output voltage of the amplifier circuit.   The motor current detection circuit includes a current transformer in which a primary winding is inserted in a negative bus in the switching circuit of the inverter circuit, and an amplification circuit that amplifies a conversion voltage of a current flowing in the secondary winding of the current transformer with a predetermined gain. The DC motor control device according to claim 1, wherein the control circuit calculates the torque current based on an output voltage of the amplifier circuit.   4. The DC according to claim 1, wherein the control circuit generates the torque current information to be output to the outside as an analog voltage signal in which the torque current is assigned to a predetermined voltage range. 5. Motor control device.   The said control circuit produces | generates the torque current information output to the said exterior as a pulse signal which prescribed | regulated torque current with the pulse number in a fixed time, The Claim 1 characterized by the above-mentioned. DC motor control device.   The control circuit detects the offset voltage of the amplifier circuit before starting the operation of the DC motor, and detects the value obtained by subtracting the offset voltage from the output voltage of the amplifier circuit when the operation of the DC motor is started. The DC motor control device according to claim 2, wherein the DC motor control device is used as a motor current. A DC motor in which the DC motor control device according to any one of claims 1 to 6 is incorporated, and a ventilation fan mounted with a fan that is rotationally driven by the DC motor and causes a flow of ventilation air.
A ventilator comprising: a controller that gives a speed command to the DC motor control device based on torque current information and a rotation pulse signal from the DC motor control device and controls the air volume of the ventilation fan.

Images