JP2015222914A - Control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize load control according to a pulse control signal even if amplitude of the pulse signal for load control changes due to change of one power supply voltage within a plurality of power supply voltages.SOLUTION: A microcomputer 200 outputs a pulse signal Pc for controlling a load current Id. The pulse signal Pc has amplitude according to a power supply voltage VCC. A level conversion circuit 360 outputs a pulse signal Pc1 which is generated by converting the amplitude of the pulse signal Pc to a power supply voltage VDD. A voltage dividing circuit 370 outputs a pulse signal Pc2 having amplitude according to a standard value of the power supply voltage VCC, by dividing the pulse signal Pc1. The load current Id is controlled to an amount of current according to an integrated voltage of the pulse signal Pc2 by a low-pass filter 310, an operational amplifier 320, and a driver transistor 330.

Description

  The present invention relates to a control device, and more particularly to a control device that uses a plurality of power supply voltages.

  Japanese Patent Application Laid-Open No. 4-276564 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2002-82139 (Patent Document 2) describe a power supply voltage monitoring device in an apparatus using a plurality of power supply voltages.

  Patent Document 1 describes a configuration of a monitoring circuit for monitoring an abnormality in another power supply voltage using one power supply voltage among a plurality of power supply voltages. In particular, Patent Document 1 discloses a configuration for monitoring an abnormality of a negative power supply voltage.

  Patent Document 2 describes a configuration for monitoring negative voltage anomalies using the outputs of two comparators.

JP-A-4-276564 JP 2002-82139 A

  In a control device using a plurality of power supply voltages, a circuit configuration in which a drive circuit operated by another power supply voltage controls the operation of a load according to a pulse signal generated by one of the plurality of power supply voltages. May apply.

  With the above configuration, when the amplitude of the pulse signal changes due to fluctuations in the power supply voltage, the operation of the drive circuit with respect to the pulse signal having the same pulse width (duty ratio) changes, thereby affecting the load control. Concerned about giving.

  The present invention has been made to solve such a problem, and an object of the present invention is to change the amplitude of a pulse signal for load control due to fluctuations in one of a plurality of power supply voltages. Even so, it is to stabilize the load control according to the pulse signal.

  A control device according to the present invention includes a first power supply wiring, a voltage adjustment circuit, a second power supply wiring, a control arithmetic unit connected to the second power supply wiring, and a drive circuit. The first power supply wiring supplies a first power supply voltage. The voltage adjustment circuit steps down the first power supply voltage of the first power supply wiring to generate a second power supply voltage. The second power supply line transmits the second power supply voltage generated by the voltage adjustment circuit. The control calculation unit generates a first pulse signal having an amplitude according to the second power supply voltage for controlling the operation of the load. The drive circuit is configured to adjust the control amount of the load according to the first pulse signal from the control calculation unit. The drive circuit includes a first level conversion circuit connected to the first power supply wiring, a second level conversion circuit, and a control amount adjustment unit. The first level conversion circuit is configured to convert the first pulse signal into a second pulse signal having an amplitude according to the first power supply voltage. The second level conversion circuit is configured to reduce the amplitude of the second pulse signal from the first level conversion circuit in accordance with the ratio of the standard value of the second power supply voltage to the standard value of the first power supply voltage. Is done. The control amount adjustment unit is configured to adjust the control amount of the load according to the pulse signal output from the second level conversion circuit.

  As an example, the second level conversion circuit is configured by a voltage dividing circuit having a voltage dividing ratio according to a ratio of standard values. Alternatively, the control amount adjusting unit controls the amount of current supplied from the first power supply wiring to the load according to the integrated voltage of the second pulse signal.

  According to the above control device, the pulse signal (first signal) for controlling the load by the fluctuation of the power supply voltage (second power supply voltage) of the control arithmetic unit (microcomputer) among the first and second power supply voltages. The amplitude of the pulse signal input to the control amount adjustment unit by the first and second level conversion circuits is constant voltage according to the standard value of the second power supply voltage even if the amplitude of Can be maintained. Therefore, even if the amplitude of the first pulse signal changes due to the fluctuation of the second power supply voltage, the load control amount characteristic with respect to the pulse width (duty ratio) of the first pulse signal does not change. Can be stabilized.

  According to the present invention, even if the amplitude of a pulse signal for load control changes due to fluctuations in one of the plurality of power supply voltages, the load control according to the pulse signal can be stabilized. .

It is a block diagram explaining the structure of the control apparatus according to embodiment of this invention. It is a circuit diagram explaining the structure of the drive circuit according to a comparative example. It is a wave form diagram for demonstrating the control action by the drive circuit according to a comparative example. It is a schematic circuit diagram explaining the structure of the drive circuit according to this Embodiment. It is a wave form diagram for demonstrating the control action by the drive circuit according to this Embodiment.

  Embodiments of the present invention will be described below in detail with reference to the drawings. In the following description, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated in principle.

FIG. 1 is a block diagram illustrating a configuration of a control device according to the embodiment of the present invention.
Referring to FIG. 1, control device 1 according to the present embodiment includes a transformer 20, an AC / DC conversion circuit 30, voltage regulators 40 and 50, smoothing capacitors 45 and 55, power supply wirings 100 and 110, A ground wiring 120, a microcomputer 200, and a drive circuit 300 are included.

  The primary side winding of the transformer 20 is electrically connected to the external power source 10 via a not-shown outlet or the like. The external power supply 10 is typically a commercial system power supply of 100 VAC to 200 VAC. The transformer 20 converts the AC voltage from the external power supply 10 according to the ratio of the primary side winding and the secondary side winding, and outputs it to the secondary side winding.

  The AC / DC conversion circuit 30 converts the AC voltage output to the secondary winding of the transformer 20 into a DC voltage and inputs the DC voltage to the voltage regulator 40. The voltage regulator 40 DC / DC converts the DC voltage from the AC / DC conversion circuit 30 to the power supply voltage VDD. The power supply voltage VDD is output to the power supply wiring 100. The power supply voltage VDD is controlled to 15V, for example. The power supply wiring 100 serves to supply a power supply voltage VDD to each circuit. Smoothing capacitor 45 is connected between power supply wiring 100 and ground wiring 120 to smooth power supply voltage VDD.

  The voltage regulator 50 steps down the power supply voltage VDD of the power supply wiring 100 and converts it to the power supply voltage VCC. The power supply voltage VCC is controlled to 5V, for example. The power supply voltage VCC is output to the power supply wiring 110. The power supply wiring 110 supplies the power supply voltage VCC output from the voltage regulator 50 to each circuit. Smoothing capacitor 55 is connected between power supply wiring 110 and ground wiring 120 to smooth power supply voltage VCC.

  The microcomputer 200 is connected to the power supply wiring 110 and the ground wiring 120. That is, the microcomputer 200 operates upon receiving the supply voltage VCC. The microcomputer 200 outputs a control signal for controlling the operation of the load 500. That is, the control signal is generated using the power supply voltage VCC. In the present embodiment, it is assumed that the control signal is a pulse signal whose amplitude is the power supply voltage VCC.

  The drive circuit 300 controls the operation of the load 500 based on a control signal from the microcomputer 200. For example, the drive circuit 300 controls the current supplied to the load 500 according to the control signal.

  FIG. 2 shows a comparative example of the drive circuit 300 (FIG. 1). FIG. 3 shows a waveform diagram for describing a control operation by drive circuit 300 # (comparative example) shown in FIG.

  Referring to FIG. 2, microcomputer 200 generates control signal Pc according to the calculation result for controlling the operation of load 500. As described above, the control signal Pc is a pulse signal whose amplitude is the power supply voltage VCC. Hereinafter, the control signal Pc is also referred to as “pulse signal Pc”.

  Referring to FIG. 3, pulse signal Pc has a predetermined period T. The pulse width W in each cycle of the pulse signal Pc, that is, the duty ratio (W / T), which is the ratio of the pulse width W to the cycle T, is controlled by the microcomputer 200 in order to adjust the supply current to the load 500. The For example, the microcomputer 200 increases the duty ratio when the supply current to the load 500 is increased, while the duty ratio decreases when the supply current is decreased.

  Referring to FIG. 2 again, drive circuit 300 # according to the comparative example includes a low-pass filter 310, an operational amplifier 320, and a drive transistor 330.

  The low-pass filter 310 includes an RC integration circuit, and generates a DC voltage obtained by integrating the pulse signal Pc at the node Na. The operational amplifier 320 constitutes a voltage follower circuit and outputs a drive voltage Vdv. The drive voltage Vdv is input to the control electrode (base) of the drive transistor 330.

  The drive transistor 330 is electrically connected in series with the load 500 between the power supply wiring 100 and the ground wiring 120. Thereby, the load current Id supplied to the load 500 changes according to the drive voltage Vdv input to the control electrode of the drive transistor 330.

  The drive voltage Vdv is feedback-controlled by the voltage follower circuit formed by the operational amplifier 320 in the same manner as the voltage at the node Na. Here, the voltage of the node Na, that is, the output voltage of the low-pass filter 310 is represented by the product of the amplitude of the pulse signal Pc and the duty ratio. As a result, the operation of the load 500 can be controlled by adjusting the pulse width W (duty ratio) of the pulse signal Pc. The load 500 is configured by an electric motor whose output torque changes according to the load current Id, for example.

  Here, consider the control of the load 500 when the power supply voltage VCC fluctuates. For example, in the configuration of FIG. 1, when the input and output of the voltage regulator 50 are short-circuited, the power supply voltage VCC, which is the power source of the microcomputer 200, increases. On the other hand, the power supply voltage VDD is stable even if such a short circuit occurs.

  Generally, for the microcomputer 200, the operation guarantee voltage range of the power supply voltage is preset as a specification value. Therefore, when the power supply voltage VCC is out of the guaranteed operating voltage range, the microcomputer 200 stops its operation, so that the operation of the load 500 is also stopped.

  However, even if the fluctuation of the power supply voltage VCC falls outside the guaranteed operating voltage range, the microcomputer 200 does not always stop operating. In such a case, there is a possibility that the control of the load 500 by the microcomputer 200 may be continued under the state where the amplitude of the pulse signal Pc is changed due to the fluctuation of the power supply voltage VCC.

  Referring to FIG. 3 again, it is assumed that the amplitude of pulse signal Pc has increased from normal voltage V1 (for example, 5V) to voltage V2 (for example, about 8V) due to fluctuations in power supply voltage VCC. That is, the voltage V1 has an amplitude according to the standard value of the power supply voltage VCC.

  The drive voltage Vdv is assumed to be Va when the power supply voltage VCC is normal. The voltage Va is represented by Va = V1 · D using the duty ratio D (D = W / T) of the pulse signal Pc. On the other hand, when the amplitude of the pulse signal Pc increases as the power supply voltage VDD increases, the drive voltage Vdv increases to Vb. Vb = V2 · D.

  As described above, the characteristic of the load current Id with respect to the duty ratio D of the pulse signal Pc changes according to the rise of the power supply voltage VCC. When the drive voltage Vdv rises, the supply current by the drive transistor 330 increases, so the load current Id increases.

  As a result, the drive voltage Vdv changes for the same pulse width (duty ratio) of the pulse signal Pc. As a result, supply of a load current Id different from the original control command may affect the control of the load 500.

  FIG. 4 shows a configuration of drive circuit 300 (FIG. 1) according to the present embodiment. Further, FIG. 5 shows a waveform diagram for explaining the operation of the drive circuit 300.

  Referring to FIG. 4, drive circuit 300 further includes a level conversion circuit 360 and a voltage dividing circuit 370 as compared with drive circuit 300 #.

  The level conversion circuit 360 receives the pulse signal Pc output from the microcomputer 200 and outputs the pulse signal Pc1 to the output node Nc. Voltage dividing circuit 370 includes resistance elements R1 and R2 connected in series between output node Nc of level conversion circuit 360 and ground wiring 120.

  Level conversion circuit 360 includes transistors Q1 and Q2. The transistor Q1 is an NPN transistor, and the transistor Q2 is a PNP transistor having a characteristic opposite to that of the transistor Q1.

  Transistor Q1 is electrically connected between node Nb and ground line 120. The pulse signal Pc from the microcomputer 200 is input to the control electrode (base) of the transistor Q1.

  Transistor Q2 is electrically connected between power supply line 110 and output node Nc. The control electrode (base) of the transistor Q2 is pulled up to the power supply voltage VDD via a resistance element and is also electrically connected to the node Nb.

  Since the transistor Q1 is turned off during the logic low level (L level) period of the pulse signal Pc, the voltage at the node Nb becomes the power supply voltage VDD. Thereby, the transistor Q2 is also turned off. Since the output node Nc is pulled down to the ground voltage GND by the resistance elements R1 and R2, the output node Nc becomes the ground voltage GND when the transistor Q2 is turned off.

  On the other hand, since the transistor Q1 is turned on during the logic high level (H level) period of the pulse signal Pc, the node Nb is electrically connected to the ground wiring 120. Thereby, the transistor Q2 is turned on. Thereby, the voltage of the output node Nc becomes the power supply voltage VDD.

  Referring to FIG. 5, pulse signal Pc1 output to output node Nc of level conversion circuit 360 has the same pulse width (duty ratio D) as pulse signal Pc. Further, the amplitude of the pulse signal Pc1 is the power supply voltage VDD.

  Referring to FIG. 4 again, the voltage dividing circuit 370 outputs a pulse signal Pc2 obtained by dividing the pulse signal Pc1 from the level conversion circuit 360. The pulse signal Pc2 is input to the low pass filter 310.

  The voltage dividing ratio DR in the voltage dividing circuit 370 is set to DR = V1 / VDD. The electric resistances of the resistance elements R1 and R2 are determined so that the voltage dividing ratio DR is obtained. Thereby, it is understood that the amplitude of the divided pulse signal Pc2 is VDD · DR = V1.

  Similar to drive circuit 300 # (comparative example) in FIG. 2, drive voltage Vdv is controlled to a DC voltage obtained by integrating pulse signal Pc2 by low-pass filter 310 and operational amplifier 320 (voltage follower circuit).

  Referring again to FIG. 5, pulse signal Pc2 has the same pulse width (duty ratio) as pulse signal Pc, and its amplitude is voltage V1 when power supply voltage VCC is normal. Thus, the amplitude of the pulse signal Pc2 generated by the level conversion circuit 360 and the voltage dividing circuit 370 is maintained at V1 even when the power supply voltage VCC varies.

  As a result, even if the amplitude of the pulse signal Pc is expanded from V1 to V2 due to the fluctuation of the power supply voltage VCC, the drive voltage Vdv according to the pulse signal Pc2 is not Vb based on the voltage V2 (Vb = V2 · D), but Va (Va = V1 · D).

  Therefore, even if the amplitude of the pulse signal Pc changes due to fluctuations in the power supply voltage VCC, if the power supply voltage VDD is stable, the drive voltage Vdv for the same pulse width (duty ratio) of the pulse signal Pc can be maintained constant. As a result, the characteristic of the load current Id with respect to the duty ratio D of the pulse signal Pc corresponding to the control command from the microcomputer 200 does not change. As a result, even if the power supply voltage VCC of the plurality of power supply voltages VCC and VDD varies and the amplitude of the pulse signal Pc from the microcomputer 200 changes, the control of the load 500 according to the pulse signal Pc is stabilized. be able to.

  In the driving circuit 300 shown in the present embodiment, the level conversion circuit 360 corresponds to a “first level conversion circuit”, and the voltage dividing circuit 370 corresponds to a “second level conversion circuit”. The low-pass filter 310, the operational amplifier 320, and the driving transistor 330 correspond to a “control amount adjustment unit”. Note that the level conversion circuit 360 and the voltage dividing circuit 370 shown in FIG. 3 are merely examples, and any circuit configuration that exhibits an equivalent function can be applied. Similarly, the circuit configuration for adjusting the load current Id by the low-pass filter 310, the operational amplifier 320, and the driving transistor 330 has an equivalent function if the control amount of the load 500 can be adjusted according to the pulse signal Pc2. Arbitrary circuit configurations can be applied.

  That is, in the present embodiment, the load current Id corresponds to a “load control amount”, and the microcomputer 200 corresponds to a “control operation unit”. Further, the pulse signal Pc from the microcomputer 200 corresponds to the “first pulse signal”, the pulse signal Pc1 from the level conversion circuit 360 corresponds to the “second pulse signal”, and the power supply voltage VDD is set to “first pulse signal”. The power supply voltage VCC corresponds to the “second power supply voltage”.

  Load 500 controlled by the control device according to the present embodiment is, for example, an electric motor whose output torque changes according to the supply current. However, the control device of the present invention can be applied to any load as long as the device can be controlled according to the pulse width (duty ratio) of the pulse signal.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 control device, 10 external power supply, 20 transformer, 30 conversion circuit, 40, 50 voltage regulator, 45, 55 smoothing capacitor, 100 power supply wiring (VDD), 110 power supply wiring (VCC), 120 ground wiring, 200 microcomputer, 300 Drive circuit, 310 low-pass filter, 320 operational amplifier, 330 drive transistor, 360 level conversion circuit, 370 voltage divider circuit, 500 load, GND ground voltage, Id load current, Pc, Pc1, Pc2 pulse signal, Q1, Q2 transistor, R1, R2 resistance element, T period (pulse signal), W pulse width, VCC, VDD power supply voltage, Vdv drive voltage.

Claims (3)

A first power supply wiring for supplying a first power supply voltage;
A voltage adjustment circuit for generating a second power supply voltage by stepping down the first power supply voltage of the first power supply wiring;
A second power supply wiring for transmitting the second power supply voltage generated by the voltage adjustment circuit;
A control operation unit that is connected to the second power supply wiring and generates a first pulse signal having an amplitude according to the second power supply voltage for controlling the operation of a load;
A drive circuit for adjusting a control amount of the load according to the first pulse signal from the control calculation unit;
The drive circuit is
A first level conversion circuit connected to the first power supply wiring for converting the first pulse signal into a second pulse signal having an amplitude according to the first power supply voltage;
Second level conversion for reducing the amplitude of the second pulse signal from the first level conversion circuit according to the ratio of the standard value of the second power supply voltage to the standard value of the first power supply voltage Circuit,
A control amount adjustment unit for adjusting a control amount of the load according to a pulse signal output from the second level conversion circuit;   The control device according to claim 1, wherein the second level conversion circuit includes a voltage dividing circuit having a voltage dividing ratio according to the ratio of the standard values.   The control device according to claim 1, wherein the control amount adjustment unit controls the amount of current supplied from the first power supply wiring to the load in accordance with an integrated voltage of the second pulse signal.

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