JP2014109515A - Pump controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insufficient voltage detection circuit suitable for a pump controller that controls a liquid level of conductive liquid stored in a liquid tank to a desired state.SOLUTION: An electric pump controller is configured such that AC voltage decreased while insulated via a transformer 20 from an external AC power source is applied to each of electrode pairs 21, 22, and 23 for detecting a liquid level of conductive liquid 2 stored in a liquid tank 1 and, based on liquid information on the basis of the conduction states of these electrode pairs, the liquid level is controlled to a desired state via the electric pump and an invertor 5 that drives the electric pump at a variable speed. An insufficient voltage detection circuit 30 is configured to detect that a DC voltage obtained by rectifying decreased AC voltage has decreased below a preset determination value. When the insufficient voltage detection circuit 30 detects the decrease in the DC voltage, a determination is made that the external AC power source went out, and various pieces of information about the electric pump controller are stored in an EEPROM 13 as a non-volatile memory.

Description

  According to the present invention, a liquid tank is provided by a pump device including a pump (hereinafter referred to as an electric pump) that is driven by an electric motor that supplies or discharges liquid to or from the liquid tank, and an inverter that drives the electric pump at a variable speed. The present invention relates to a pump controller that controls a liquid level of a stored liquid to a desired state.

  In this type of pump controller, power is supplied to components such as a CPU (central processing unit, also referred to as a microcomputer) that performs overall control and an inverter that drives the electric pump at a variable speed. When a voltage drop occurs, this is promptly detected, and the operation state of each component device immediately before the voltage drop occurs is saved in a nonvolatile memory, and then the operation of each component device is stopped. After the decrease is recovered, this is detected and the operation of each component device is restarted based on the content stored in the nonvolatile memory.

  For example, in the conventional apparatus disclosed in Patent Document 1 below, as a means for detecting a power failure or a voltage drop, a means for monitoring the intermediate DC voltage of the inverter is provided, and the intermediate DC voltage is monitored by means for monitoring this intermediate DC voltage. Is detected to be equal to or less than a predetermined determination value, it is assumed that a power failure has occurred, and the state immediately before the occurrence of the power failure is saved and saved in a nonvolatile memory.

Japanese Patent Laid-Open No. 2001-268888

  However, since an intermediate DC voltage of several hundred volts is normally applied to the inverter, the means for monitoring the intermediate DC voltage of the inverter in the conventional device insulates the high voltage circuit components and the DC voltage value. Therefore, there is a demand for a circuit configuration having a function to detect the power supply, and there is a problem that the means for monitoring the intermediate DC voltage as a means for detecting a power failure or a voltage drop becomes large and expensive.

  An object of the present invention is to provide an electric pump controller that solves the above-described problems and has a small and inexpensive means for detecting a power failure or voltage drop.

  The present invention applies an AC voltage stepped down while insulating from an external AC power source to a plurality of electrode pairs having different lengths for detecting the liquid level of the conductive liquid stored in the liquid tank. Based on the liquid level information based on the conductive state of these electrode pairs, the liquid level is controlled to a desired state by controlling an inverter that drives the electric pump that supplies or discharges the liquid to or from the liquid tank at a variable speed. The pump controller includes an undervoltage detection circuit that monitors the stepped down AC voltage applied to the electrode pair and sets the AC power supply as an undervoltage detection signal when detecting that the AC voltage has dropped below a predetermined determination value. It is characterized by that.

  Further, in the above, when the undervoltage detection circuit detects a decrease in the stepped-down AC voltage or a DC voltage obtained by rectifying the voltage, various information of the electric pump controller is saved and stored in a nonvolatile memory. Shall.

  The pump controller that controls the liquid level of the conductive liquid stored in the liquid tank to a desired state includes a liquid level detection circuit for detecting the liquid level of the conductive liquid. The liquid level detection circuit includes a plurality of electrode pairs for detecting the liquid level of the conductive liquid stored in the liquid tank, and steps down the voltage while insulating each of the plurality of electrode pairs from an external AC power source. The liquid level of the conductive liquid in the liquid tank is detected by applying the AC voltage and monitoring the conduction state of each electrode pair.

  The present invention is made by paying attention to the fact that the liquid level detection circuit of the electric pump controller uses an AC voltage that is insulated from an external AC power source and is stepped down, and detects the liquid level. For this reason, the power supply voltage is interrupted or lowered by utilizing the characteristic that the stepped-down AC voltage used for this purpose is proportional to the power supply voltage. For this reason, the undervoltage detection circuit that detects power failure and voltage drop of the power supply provided in the pump controller does not need to be insulated from the main circuit of the inverter and can be configured with low-voltage rated electronic components, so it is small and inexpensive. A simple circuit.

Schematic conceptual configuration diagram of an electric pump controller showing an embodiment of the present invention Partial detailed circuit configuration diagram of FIG. Waveform diagram explaining the operation of FIG. Waveform diagram explaining the operation of FIG.

  FIG. 1 is a schematic conceptual configuration diagram of a pump controller showing an embodiment of the present invention.

  In this figure, 1 is a liquid tank for storing a conductive liquid 2 such as water, and 4 is a conductive liquid 2 once stored in the liquid tank 1 via a pipe 3 at each end (for example, a faucet for each household) ), An AC electric pump that feeds the electric pump 4 under pressure, 5 is an inverter that drives the electric pump 4 at a variable speed, 10 is a CPU (central processing unit) that performs overall control of the electric pump controller, 11 is an inverter 5 A communication interface for performing data communication processing with the CPU 10, a sensor interface 12 for transmitting state monitoring signals from various state monitoring sensors such as a flow sensor and a pressure sensor installed in the pipe 3 to the CPU 10, 13 is an EEPROM as a non-volatile memory for storing various information of the pump controller, and 20 is a component of the pump controller. Transformers 21, 22,... 23 are transformers 20 for generating a low voltage, for example, an AC voltage stepped down to AC 12 V while being insulated from an external AC power source (for example, AC 200 V) such as a commercial power source. A plurality of electrode pairs having different lengths to which an AC voltage stepped down is applied to the generated AC12V. In the example shown in the drawing, the electrode length is sequentially increased in the order of 21, 22,..., And the immersion level is deeper.

  A liquid level detection circuit 24 monitors the liquid level state of the conductive liquid 2 in the liquid tank 1 (for example, the state of full water, low water, drought, etc.). The liquid level detection circuit 24 includes a detection circuit constituted by a resistor, a diode, a comparator element, a photocoupler element, and the like for each of the electrode pairs 21, 22,... 23, and the electrode pairs 21, 22,. The liquid level of the conductive liquid 2 stored in the liquid tank 1 is detected depending on which level of the electrode pair is conductive.

  That is, since the electrode pair located below the liquid level at the liquid level h shown in the figure is in a conductive state through the liquid in the liquid tank, the AC 12V low voltage AC is passed through the electrode pair to the series circuit of the detection resistors R1 and R2. A voltage will be applied. As a result, the liquid level of the conductive liquid 2 is detected by transmitting to the CPU 20 an operating state in which each of the photocoupler elements PC via the corresponding diode D and comparator element CP is turned on and off every half cycle. Can do. At this time, the wear based on the electrolysis action of the electrode pair is reduced by slightly limiting the alternating current flowing through the electrode pair in the conductive state.

  Further, a voltage DC17V (+17 in the figure) obtained by rectifying AC12V is obtained at both ends of the capacitor 26 by passing the diode 25 and the capacitor 26 with respect to AC12V from the transformer 20. In order to utilize the characteristic that DC17V obtained by rectifying the AC12V is proportional to the voltage of the external AC power supply, this rectified voltage is applied as a DC power supply to an undervoltage detection circuit 30 described later.

  As described above, the pump controller includes an external AC power supply for each of the plurality of electrode pairs 21, 22,... 23 for detecting the liquid level of the conductive liquid 2 stored in the liquid tank 1. Is applied with an AC voltage that is stepped down to a low voltage while being insulated by the transformer 20, and a liquid level detection signal is output from the liquid level detection circuit 24 based on the conduction state of these electrode pairs 21, 22,... The Then, the CPU 10 determines the respective liquid level state in the liquid tank 1 in accordance with the liquid level detection signal from the liquid level detection circuit 24, and controls the inverter 5 to drive the electric pump 4 at a variable speed. The operation of controlling the liquid level of the conductive liquid 2 to a desired state is performed.

  FIG. 2 is a detailed circuit configuration diagram of the undervoltage detection circuit 30 shown in FIG. 1. A resistor 31 and 32 constitute a voltage detection circuit, and a resistor 33 and a constant voltage diode 34 constitute a reference voltage circuit. . The comparator element 35 compares the detection voltage V2 of the voltage detection circuit with the reference voltage Vz (the zener voltage of the low voltage diode 34) generated by the reference voltage circuit, and sets the output voltage Vc to L level when V2 ≧ Vz. When V2 <Vz, the output voltage Vc is set to the H level. This output voltage Vc is input to the CPU 10 by turning the photocoupler element 37 times.

  The operation of the undervoltage detection circuit 30 shown in FIG. 2 will be described below with reference to the waveform diagrams shown in FIGS.

  FIG. 3 shows voltage waveforms at various portions for explaining the operation of the undervoltage detection circuit 30 when an AC power supply such as a commercial power supply for supplying power to the components constituting the pump controller of the present invention is normal. V1 indicates an input voltage of the undervoltage detection circuit 30, that is, a waveform of a rectified voltage (+17 in the figure) across the capacitor 26, and V2 indicates a voltage waveform obtained by dividing the V1 by the resistor 31 and the resistor 32. Vz is a reference voltage, and +17 shown in the figure, which is applied to the circuit of the resistor 33 and the constant voltage diode 34, indicates a voltage waveform that is set to a substantially constant value Vz by the constant voltage diode 34.

  In FIG. 3, the voltage V2 is always in the relationship of V2 ≧ Vz, so that the output Vc of the comparator element 35 is always at the logic “L” level. As a result, the photocoupler element 37 via the resistor 36 causes the logic “L”. ”Level signal is transmitted to the CPU 10, and the CPU 10 determines that the voltage of the AC power supply is normal and not normal.

  FIG. 4 shows a case in which the power supply voltage drops to, for example, about 50% of normal due to a power failure (including instantaneous power failure) or a power failure due to an AC power source such as a commercial power source that supplies power to the components of the pump controller of the present invention. 6 is a waveform diagram for explaining the operation of the undervoltage detection circuit 30 of FIG.

  In FIG. 4, V1 ′ indicates an input voltage waveform applied to the undervoltage detection circuit 30 when V1 shown in FIG. 3 (broken line waveform in FIG. 4) abnormally decreases, and V2 ′ replaces V1 ′ with the resistor 31. And Vz indicates a voltage waveform of a reference voltage that is made substantially constant by the constant voltage diode 34.

  Here, when a region having a relationship of V2 ′ <Vz exists in a predetermined period (for example, a period of 2 milliseconds or more), the output Vc of the comparator element 35 becomes a logic “H” level in this region, Therefore, the logic “H” level signal is transmitted to the CPU 10 from the photocoupler element 37 via the resistor 36 (see Vc in FIG. 4). Thus, the CPU 10 determines that the AC power supply has fallen into an abnormal undervoltage state. As a result, the CPU 10 performs an operation of saving and storing various information of the pump controller required for the electric pump control in the EEPROM 13 before the power supply is completely shut down.

  Further, the condition for returning from a power failure to a normal state is that a state in which V2> Vz is satisfied continuously for a predetermined period (a period longer than the predetermined period, for example, a period of 100 milliseconds or more). Exist. This condition is determined by counting the period when the output voltage Vc of the comparator element 10 is at the logic “L” level in the CPU 10. It is detected that the period when the output voltage Vc of the comparator element 10 is at the logic “L” level continues for a period exceeding the period exceeding 100 milliseconds. Then, the CPU 10 reads various information of the saved electric pump controller from the EEPROM 13.

  As described above, the low-voltage AC voltage (AC12V) for detecting the liquid level of the conductive liquid 2 stored in the liquid tank 1 is shared when an AC power supply abnormality is detected. Since the undervoltage detection circuit 30 for detecting an abnormal state can be easily configured with electronic components having a low voltage rating, the cost of the circuit can be reduced. When the AC power supply is in an abnormal state, it is possible to take measures such as saving various information necessary for the electric pump operation.

  DESCRIPTION OF SYMBOLS 1 ... Liquid tank, 2 ... Conductive liquid, 3 ... Piping, 4 ... Electric pump, 5 ... Inverter, 10 ... CPU, 11 ... Communication interface, 12 ... Sensor interface, 13 ... EEPROM, 20 ... Transformer, 22 and 22 23 ... Electrode pair, 24 ... Liquid level detection circuit, 25 ... Diode, 26 ... Capacitor, 30 ... Undervoltage detection circuit, 31-33 ... Resistance, 34 ... Constant voltage diode, 35 ... Comparator element, 36 ... Resistor, 37 ... Photocoupler element.

Claims (3)

A plurality of electrode pairs having different lengths for detecting the liquid level of the conductive liquid stored in the liquid tank are applied with an AC voltage stepped down while being insulated from an external AC power source. Based on the liquid level state based on the conduction state of
In a pump controller that controls an inverter that drives an electric pump that supplies or discharges liquid to the liquid tank at a variable speed to control the liquid level to a desired state, a reduced AC voltage applied to the electrode pair A pump controller, comprising: an undervoltage detection circuit that monitors and detects that the voltage has fallen below a predetermined determination value, and serves as an undervoltage detection signal for the AC power supply. The electric pump controller according to claim 1,
The pump controller according to claim 1, wherein the undervoltage detection circuit detects that a DC voltage obtained by rectifying the stepped-down AC voltage is lower than a predetermined determination value. In the electric pump controller according to claim 1 or 2,
When the undervoltage detection circuit detects a drop in the AC voltage or a DC voltage obtained by rectifying the AC voltage, various information of the electric pump controller is saved and stored in a nonvolatile memory. .

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