JP2011166947A - Power supply apparatus - Google Patents

Abstract

In a power supply apparatus, when load driving is performed by DUTY control by PWM, in low DUTY control, since it is close to intermittent operation, there has been a problem of noise due to load swaying. In addition, the load stress on the power source is increased, and at the same time, the influence on noise is increased, so that noise reduction parts such as a coil are required, and extra design man-hours are increased.
The voltage value in PWM control in load drive is controlled between two or more voltages, and the potential difference between HI and LO is reduced to reduce noise such as beating caused by voltage fluctuations of a fan motor or the like. At the same time, by reducing the load stress on the power supply, the influence of noise is reduced and noise countermeasures are simplified.
[Selection] Figure 2

Description

  The present invention relates to a power supply device mounted on a device that drives a load.

In general, there is a method of using PWM control for controlling driving of a load. If a fan motor is cited as a load, a control technique by changing a carrier frequency of a driving PWM signal of the fan motor is disclosed. (For example, Patent Document 1)
In addition, the pulse waveform that is the source of the external shape of the PWM control waveform is not used at 100% ON / OFF, but a technique that uses an offset voltage to prevent distortion of the logic IC is disclosed. Has been. (For example, Patent Document 2)

JP 2007-252034 A Japanese Patent Laid-Open No. 11-145821

  However, since the amplitude of general PWM control including the above-mentioned Patent Document 1 is 100% and ON / OFF control is performed with 0% output, transient stress of 100% or 0% is always applied to the load and the power source. In addition, since the ON and OFF currents fluctuate greatly, the influence on the noise is large.

  In addition, when the load is a fan motor, PWM control with low DUTY reduces noise because it can not be denied even if it is changed to any carrier frequency unless it is set to a very large carrier frequency ignoring noise reduction. When I tried to do it, there was noise caused by the fan motor's beating.

  The pulse waveform disclosed in Patent Document 2 is an input waveform for improving the output of the logic IC and cannot be used for load control.

  The present invention solves the above-mentioned conventional problems, and uses a fan motor for the load by controlling the voltage value in the PWM control in the load drive between two or more voltages and reducing the potential difference between HI and LO. By reducing noise such as beats generated at the same time, and simultaneously reducing load stress on the power supply, the effect of noise is reduced and noise countermeasures are facilitated.

In order to solve the above-mentioned problem, the present invention is a power supply device including a control unit that performs PWM control on a load, and the control unit controls the load by a voltage changing unit that changes a voltage value of PWM control. It is configured to control using at least two voltage values of HI and LO of the PWM control to be driven.

  As a result, the stress applied to the load can be reduced by reducing the potential difference of the voltage waveform applied to the load, and at the same time the load stress on the power supply can be reduced, thereby reducing the influence of noise and facilitating noise countermeasures. it can.

  The power supply apparatus of the present invention controls the voltage value in PWM control in load driving between two or more voltages, and reduces the potential difference between HI and LO, thereby generating a beat when a fan motor is used as a load. By reducing the noise and simultaneously reducing the load stress on the power supply, the influence of the noise can be reduced and the reliability can be improved.

The block diagram which shows the function of the power supply device in embodiment of this invention Detailed circuit diagram of the power supply device in the same embodiment The flowchart which shows the operation | movement content of the power supply device in the embodiment PWM output waveform diagram of the power supply device in the same embodiment Prior art PWM output waveform diagram Supplementary diagram of PWM output waveform of power supply device in same embodiment

  The invention according to claim 1 comprises a load, a control means for performing PWM control on the load, and a voltage changing means for changing a voltage value of PWM control of the control means. Control is performed using at least two or more amplitudes of PWM control for driving a load by the voltage changing means.

  As a result, the stress applied to the load can be reduced by reducing the potential difference of the voltage waveform applied to the load, and at the same time the load stress on the power supply can be reduced, thereby reducing the influence of noise and facilitating noise countermeasures. it can.

  The invention according to claim 2 is the invention according to claim 1, wherein the load is a fan motor.

  Thus, in PWM control with low DUTY, noise such as beat can be reduced and noise can be reduced at the same time, so that practicality increases and reliability can be improved.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the apparatus includes a temperature detection unit that detects an ambient temperature, and the duty of PWM control by the control unit is set according to the temperature of the temperature detection unit. It is characterized by performing.

  As a result, not only can the load operation follow load control depending on the temperature of an air conditioner or the like, but also correction can be performed even if the load is affected by the temperature, thus increasing practicality.

  According to a fourth aspect of the present invention, in the second or third aspect of the present invention, the present invention further comprises a rotational speed detection means for detecting the rotational speed of the fan motor, and the DUTY of PWM control by the control means is the drive detection means. Correction is performed according to the detected value.

    As a result, even when the fan motor operation differs from the target value due to the influence of disturbance or various variations, correction can be performed as appropriate, so that practicality increases and reliability can be increased.

According to a fifth aspect of the invention, there is provided a current detecting means for detecting the current of the fan motor in the invention of the second or third aspect, wherein the control means is 100% for several seconds when driving the fan motor. And the current detection value is stored by the current detection means, and PWM control D
The correction of the UTY ratio is performed by comparing the current detection values acquired by the current detection means.

  As a result, even when the fan motor operation is affected by disturbances and various variations, it is possible to appropriately correct the target value by detecting individual capabilities, thereby increasing practicality. At the same time, reliability can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment)
FIG. 1 is a block circuit diagram showing a functional configuration of a power supply device according to an embodiment of the present invention.

  In FIG. 1, the power supply apparatus includes a control unit 2 that performs PWM control of a load 1, a voltage changing unit 3 that changes HI and LO values of a PWM voltage value applied to the load 1, and a current value when the load 1 is in operation. Current detection means 4 for acquiring and temperature detection means 5 for detecting the ambient temperature are provided.

  The control means 2 detects the current value of the operating state during the load operation by the current detection means 4, and performs a feedback control of the output DUTY value of the PWM control in addition to the abnormality determination, and the temperature detection means 5 A function of controlling the operating state of the load 1 according to the acquired ambient temperature is provided.

  The control unit 2, the voltage changing unit 3, the current detecting unit 4, and the temperature detecting unit 5 are collectively referred to as a power supply block 6.

  In the above configuration, details of the configuration will be described with reference to FIG.

FIG. 2 is a detailed circuit diagram of the power supply device according to the embodiment.
In the present embodiment, for convenience, it is assumed that three different voltages are used for the load. However, the present embodiment is not limited to three types.

  Further, the detailed circuit of the voltage changing means and the current detecting means in the present embodiment is an example, and the configuration is not limited to this.

  In FIG. 2, the load 1 is a fan motor, and the control means 2 outputs P01, P02, and P03 signals to the voltage changing means 3, and HI, LO to the load 1 through the voltage changing means 3. The PWM control using two or more values of the voltage value is output. P04, P05, and P06 of the control unit 2 supply voltages Va, Vb, and Vc to the circuits of the voltage detection unit 3 and the current detection unit 4, respectively, and P07 inputs the current value acquired by the current detection unit 4.

  The voltage changing means 3 constitutes a circuit that outputs three different voltages.

  The first voltage is when P01 of the control means 2 is HI output. When P01 becomes a HI output, the transistor 101 is driven, and the FET 102 is driven accordingly. The resistor 103 is a protective resistor for the gate of the FET 102, and the resistor 104 is a bias resistor for securing a potential for driving the gate with respect to the source of the FET 102. The diode 105 is a protection component for back electromotive force applied to the FET 102. Va is applied to the load 1 because there is almost no loss of the FET 102.

  The second and third voltages are when P01 of the control means 2 is LO output and P02 is HI output. When P02 becomes HI output, the transistor 106 is driven, and the FET 107 is driven accordingly. The resistor 108 is a protective resistor for the gate of the FET 106, and the resistor 109 has a role similar to that of the resistor 104 for the FET 102 and is a bias resistor for the FET 107. The diode 110 is a protection component for back electromotive force applied to the FET 107.

  The circuit in the following description including the transistor 111 is a circuit for reducing the voltage Va due to the operation of the FET 107 to a predetermined voltage. The collector voltage of the transistor 111 is Va, but the value applied to the base is determined by the output of the operational amplifier 112. The input on the + side of the operational amplifier is a value in which the voltage Vb is input by dividing the resistance 113 and the resistance 114. In order to change the input value, the transistor 115 is used, and the transistor 115 is driven, whereby the resistor 114 is short-circuited. Therefore, the voltage Vb is applied to the + side input of the operational amplifier 112. In the transistor 115, depending on whether the output of P03 of the control means 2 is HI or LO, the input on the + side of the operational amplifier becomes the voltage Vb or the voltage Vb is divided between the resistor 113 and the resistor 114. The input on the negative side of the operational amplifier 112 is divided by the resistors 116 and 117, and the output of the operational amplifier is output so that the positive potential and the negative potential are equal. Since the negative input of the operational amplifier 112 and the output of the operational amplifier 112 are short-circuited in the circuit, the output of the operational amplifier 112 is “(1 + resistance 116 ÷ resistor 117) × the positive input of the operational amplifier 112”. Needless to say, the circuit composed of the resistor 113, the resistor 114, the transistor 115, the resistor 116, and the resistor 117 is a non-inverting amplifier circuit, and the non-inverting amplifier circuit is a well-known technique.

  For the sake of convenience, in order to simplify the following description, a voltage follower circuit which is a kind of non-inverting amplifier circuit in which the resistance 116 = 0 and the resistance 117 = ∞ will be described as an example.

  In the voltage follower, the output of the operational amplifier 112 is the output of the operational amplifier 112 by substituting the resistance 116 = 0 and the resistance 117 = ∞ for “(1 + resistor 116 ÷ resistor 117) × the positive input of the operational amplifier 112”. = Since the input to the + side of the operational amplifier 112 is the + side input of the operational amplifier 112, as described above, the voltage Vb becomes the voltage Vb or the voltage Vb is divided between the resistor 113 and the resistor 114, and the output of the operational amplifier 112 is also the voltage Vb. Alternatively, the voltage Vb is divided by the resistor 113 and the resistor 114.

  For convenience, in order to simplify the following description, a voltage obtained by dividing the voltage Vb by the resistor 113 and the resistor 114 is referred to as a voltage Vd.

  Therefore, the source potential of the transistor becomes Va-base potential, in other words, Va-output of the operational amplifier 112), and the second voltage is the voltage when P02 of the control means 2 outputs HI and P03 outputs LO. Va−Vd, and the third voltage is a voltage when P02 of the control means 2 outputs HI and P03 outputs HI, and becomes voltage Va−Vb.

  Further, the diode 118 on the source side of the transistor 111 is a backflow prevention component for preventing the transistor 111 from flowing into the transistor 111 due to the voltage Va generated when P01 of the control means 2 outputs HI. In the above-described second and third voltage conditions, P01 of the control means 2 is set to LO output because the voltage Va when P01 is HI output is the second voltage Va-Vd, 3 Since it always becomes larger than the first voltage Va-Vb, priority is given regardless of the operations of P02 and P03 of the control means 2. Therefore, P01 of the control means 2 outputs LO when the second and third voltages are applied.

As a result, it differs depending on the combination of P01, P02 and P03 of the control means 2.
Two voltages can be generated.

  When the control means 2 performs PWM control on the load 1, the voltage corresponding to the HI of the PWM and the voltage corresponding to the LO are determined by the combination of P01, P02 and P03, so that the HI, LO during the PWM control applied to the load 1 are determined. Determine the voltage value.

  When a voltage is applied to the fan motor of the load 1 to drive it, a reverse voltage of the fan motor is generated. Therefore, the diode 119 is connected in parallel to the load 1 as a protective component and the forward current is used to release the reverse current. Install in the opposite direction.

  Further, in order to stabilize the voltage value of the PWM control closer to the direct current, a capacitor 120 is installed between the load 1 and GND in some cases.

  As described above, the control unit 2 can control the load 1 by arbitrarily setting the voltage values of HI and LO during PWM control via the voltage changing unit 3. Unlike normal PWM control, the potential difference between HI and LO can be set as small as possible, so that noise generated when the load 1 is driven can be reduced.

  In addition, when the load 1 is a fan motor as in the present embodiment, it is possible to reduce a beat sound generated due to variations in the rotational speed that are a concern in normal PWM control, HI, and LO.

  The current detection means 4 constitutes a circuit that detects the current flowing through the load 1 based on the voltage across the resistor 121.

  The voltage across the resistor 121 is input to the operational amplifier 122, and the voltage value across the resistor 121 is amplified by the ratio of the resistor 125, the resistor 126, the resistor 127, and the resistor 128 using differential amplification, and the voltage is supplied to P07 of the control unit 2. Output. Needless to say, the differential amplifier circuit of the operational amplifier is a well-known technique. A capacitor 123 and a capacitor 124 connected in parallel with the resistor 121 are stabilizing components for inputting a stable voltage across the resistor 121 to the operational amplifier 122. The resistor 121 is assumed to be a value that can be ignored with respect to the input impedance of the operational amplifier 122.

  The resistor 125 is the input impedance of the inverting input of the operational amplifier 122, the resistor 126 and the resistor 127 are the input impedance of the non-inverting input of the operational amplifier 122, and the resistor 128 is the feedback resistor of the operational amplifier 122. The capacitor 129, the capacitor 130, and the capacitor 131 are installed when necessary for noise reduction with respect to the input of the operational amplifier 122, but are not necessarily required.

  As described above, the current detection unit 4 detects the current using the differential amplifier circuit of the operational amplifier, and outputs the current value to P07 of the control unit 2. The control means 2 receives this current value, corrects the duty of PWM control, detects the abnormality of the load 1 and the like, and can improve the safety and reliability for driving the load 1.

  The temperature detection means 5 is constituted by a thermistor circuit, for example, and outputs a detection value to P08 of the control means 2. The control unit 2 controls the target value in the PWM control for driving the load 1 by changing the detection value of the temperature detection unit 5.

  Next, PWM control performed by the control unit 2 on the load 1 via the voltage changing unit 3 will be described with reference to FIGS.

  FIG. 3 shows a flowchart in which the control means 2 performs PWM control on the load 1 in FIG. 2, and FIG. 4 shows a time axis with respect to the output waveform to the load 1 different from the branch in the flowchart of FIG. Corresponding waveforms are divided into three parts, t1, t2, and t3.

  Since FIGS. 3 and 4 are mutually related, description will be made alternately.

  In the following description, as a condition for changing the DUTY of the PWM control of the control unit 2 with respect to the load 1, the target value of the DUTY value of the PWM control is controlled by the temperature detected by the temperature detection unit 5, and the current detection unit 4 This is performed based on the detected value.

  For PWM control, the HI and LO voltage combinations are divided into three by DUTY. For example, when the maximum output of load 1 is 100%, such as 0 to 30% is DUTY setting 1, 30 to 60% is DUTY setting 2, and 60 to 100% is DUTY setting 3, load 1 is controlled by PWM control. The ratio of the DUTY output with respect to is divided into three stages. DUTY setting 1, DUTY setting 2, and DUTY setting 3 are defined in ascending order of output.

  Further, as a correlation between FIG. 3 and FIG. 4, the output waveform in the range of DUTY setting 1 in FIG. 3 is the output waveform in the range of section t 1 and DUTY setting 2 in FIG. 4 and the output waveform in the range of section t 2 and DUTY setting 3 in FIG. The waveform is a section t3.

  S101 determines whether or not the first DUTY set value divided into three is a target. If the target of the DUTY set value is within the first range, the process proceeds to S102, and the DUTY set value If the target is the second or third target, the process proceeds to S105.

  S102 is a step that passes when the DUTY setting value is 1 as described above. First, since DUTY is the smallest range as a premise, it is necessary to control using P02 and P03 as described in FIG. Here, when P01 is output as HI, the output of P01 is given priority regardless of the outputs of P02 and P03 because of the configuration of the present embodiment. Therefore, when performing the operation according to P02 and P03, P01 is output as LO. And Step corresponds to S102.

  In S103, in the case of controlling with P02 and P03, as a condition for reducing the voltage of the voltage changing means 3, Step 03 is set to P03 = HI in order to set the voltage Va−Vb by driving the transistor 115.

  S104 is a step for performing PWM control, and is a step for performing PWM output with P02 set to HI and LO under the condition of performing PWM output with HI set to Va-Vb and LO set to 0. When P02 is set to HI, the voltage Va-Vb is output, and when it is set to LO, the voltage is cut off and the output becomes zero.

  The output waveform of the PWM control performed by the control means 2 performed at Step S102, S103, and S104 on the load 1 via the voltage changing means 3 is the waveform in the t1 section of FIG.

  S105 determines whether the target value of the DUTY setting is within the range of the DUTY setting value 2. If the target of the DUTY setting value is within the second range, the process proceeds to S106, and the target of the DUTY setting value is 3. If it is the first time, the process proceeds to S109.

S106 is a step that passes when the DUTY setting value is 2 as described above. DUTY
In the case of the range of setting 2, since it is necessary to control using P02 and P03 as in the case of the range of DUTY setting 1, it is necessary to output LO of P01 like the step of S102. Corresponds to S106.

  Further, in the range of DUTY setting 2, in order to set the voltage of HI of PWM control applied to the load 1 to Va-Vd and the voltage of LO to Va-Vb, the control always adds the voltage of HI and LO. When applying a voltage to the load 1, it is necessary to output either P01 or P02 as HI, and when driving P01, the voltage is fixed to Va. Therefore, as a condition in the range of DUTY setting 2, P02 is output as HI. That Step corresponds to S106. When P02 is fixed to HI output, if P03 is LO output, the voltage applied to the load 1 is Va-Vb, and if P03 is HI output, Va-Vd.

  S108 is a step for performing PWM control on the load 1. As described above, by alternately outputting P03 to LO output and HI output, the ratio becomes the DUTY ratio, and PWM control is performed on the load 1. To do.

  The output waveform of the PWM control performed by the control means 2 performed at Step S106, S107, and S108 on the load 1 via the voltage changing means 3 is the waveform in the t2 section of FIG. Vd in FIG. 4 is a voltage value obtained by dividing the voltage Vb between the resistor 113 and the resistor 114 as defined above.

  In addition, when the target range of the DUTY set value is changed, control is performed so that the voltage change width is always reduced.

  In FIG. 4, when the target range of DUTY setting value is changed from DUTY setting 1 to DUTY setting 2 when t1 to t2, the setting is not changed when the output by PWM control is changed from LO to HI. The voltage is changed to the next HI voltage during the interval. By doing so, the voltage is not applied to the load 1 at a stretch, and the inrush current can be minimized.

  S109 is a step that passes when the DUTY setting value is 3, as described above. In the case of the range of DUTY setting 3, unlike the case of DUTY setting 1 and DUTY setting 2, it is necessary to control using P01, P02 and P03. However, since only one type of voltage is applied to the load 1 using P02 and P03, the control of P02 and P03 is fixed. Furthermore, as described above, since the output of P01 has priority over P02 and P03, P02 and P03 do not need to consider the influence on P01. The voltage required by P02 and P03 is Va-Vd. The setting condition is that P03 is output as HI and P02 is output as HI, which correspond to the steps of S109 and S110, respectively.

  Further, although the voltage Va-Vd is always applied at P02 and P03 at S109, S110 when the DUTY setting value 3 is set, the voltage Va applied when P01 is output HI is the voltage Va-Vd. Therefore, the voltage Va is always applied to the load 1.

  Therefore, as a PWM control for the load 1 with the DUTY setting value 3, the HI voltage is set to Va and the LO voltage is set to Va−Vd, and the condition for performing the PWM control is that P01 is output as HI and LO. That Step corresponds to S111.

The output waveform of the PWM control performed by the control unit 2 performed at Steps S109, S110, and S111 on the load 1 via the voltage changing unit 3 is a waveform in the t3 section of FIG. When the target range of the DUTY setting is changed, the change is made so that the voltage amplitude is minimized at t3 as well as the description of t2.

  As described above, the voltage value when the PWM control is performed on the load 1 is changed according to the range of the DUTY setting.

  FIG. 5 shows the DUTY control in the normal PWM control, and the one corresponding to the DUTY of the PWM control shown in the t1, t2, and t3 sections in FIG. 4 is replaced.

  4 and 5 are compared, first, in the setting range of t1, that is, low DUTY, in FIG. 5, it is close to intermittent operation. Furthermore, since the voltage applied to the load changes transiently as a whole at t1, t2, and t3, it can be assumed that the inrush current to the load 1 becomes large, and it is likely to be a noise source due to intermittent current.

  FIG. 4 shows an example of an output waveform with a constant DUTY, but this is not a limitation, and the setting of DUTY is variable.

  As an example, FIG. 6 shows an output waveform when the DUTY is variable with respect to the PWM control in which the HI voltage for the load 1 is Va-Vb and the LO voltage is 0, and t1 shown in FIG. DUTY by PWM, that is, the ratio between the HI voltage and the LO voltage is the ratio between Va-Vb and 0 as shown in FIG. In the control means 2, it is possible to change DUTY by fixing P01 to LO output and P03 to HI output, and changing HI and LO time of P02 HI output and LO output. Needless to say, control is a well-known technique. 2, 3, and 4, in order for the control unit 2 to perform PWM control on the load 1, a necessary voltage is generated by the output of P01, P02, and P03 to the voltage changing unit 3. , DUTY can be changed according to the time of the combination.

  As described above, by implementing the present invention, the amplitude of the voltage for performing PWM control on the load 1 can be suppressed to a smaller value, so that the inrush current applied to the load 1 can be suppressed and noise can be reduced. can do.

  Even in the case where the output DUTY must be finely adjusted by temperature control or the like, the difference between the HI and LO voltages of the PWM waveform is small, so the voltage applied to the load 1 when the DUTY is changed Since a constant voltage that is closer to smoothness can be supplied, accurate control can be performed.

  The power supply device according to the present invention controls the voltage value in PWM control between two or more voltages, and drives the load with a voltage in which the potential difference between HI and LO is reduced. When the potential difference applied by a fan motor or the like is large, It can be applied to devices that generate noise such as roar and devices that require noise reliability.

DESCRIPTION OF SYMBOLS 1 Load 2 Control means 3 Voltage change means 4 Current detection means 5 Temperature detection means

Claims (5)

A load, a control unit that performs PWM control on the load, and a voltage changing unit that changes a voltage value of the PWM control of the control unit, and the amplitude of the PWM control that drives the load from the control unit A power supply apparatus that is controlled by using at least two or more voltage changing means. The power supply apparatus according to claim 1, wherein the load uses a fan motor. 3. The power supply apparatus according to claim 1, further comprising temperature detecting means for detecting an ambient temperature, wherein PWM control DUTY by the control means is performed according to the temperature of the temperature detecting means. 4. A rotation speed detection means for detecting the rotation speed of the fan motor, and correcting a DUTY of PWM control by the control means according to a detection value of the drive detection means. Power supply Current detection means for detecting the current of the fan motor, and the control means drives the fan motor at a rate of 100% for several seconds, stores the current detection value by the current detection means, and performs PWM control. 4. The power supply apparatus according to claim 2, wherein the correction of the DUTY ratio is performed by comparing current detection values acquired by the current detection means.