JP7286523B2 - Water supply device, control device and inverter - Google Patents

Description

TECHNICAL FIELD The present invention relates to a water supply device, a control device, and an inverter that use a pump to supply water to buildings such as collective housing and office buildings.

The water supply system is equipped with an inverter that controls the number of revolutions of the motor to adjust the output of the pump, and a power line is connected to the inverter to supply power to the motor of the pump. The inverter is, for example, a PWM inverter device that obtains a desired multiphase AC output by controlling switching elements such as transistors on and off. As a method of obtaining switching signals for on/off operation, there is a method of obtaining on/off signals for each switching element by comparing a sine wave signal, which is a voltage command for each phase, with a triangular wave signal, which is a modulating wave. The frequency of the modulated wave at this time is called a carrier frequency.

If the carrier frequency is low, there is little loss during on/off control of the switching element, but the magnetic noise generated when the motor is driven increases. Conversely, if the carrier frequency is increased (e.g., 10 kHz or higher), the loss during on/off control of the switching element increases, but the frequency of the magnetic sound exceeds the human audible range, making it difficult to perceive unpleasant sounds. .

In such a water supply apparatus, the pump may be driven even in a quiet environment such as at night. Therefore, noise reduction is desired, and the inverter is often operated at a relatively high carrier frequency. For example, Patent Literature 1 describes a driving method for suppressing noise by increasing the carrier frequency during off-peak hours such as at night.

JP-A-60-157473

Inverter overheating protection when the ambient temperature in the location where such water supply equipment is installed is higher than expected, or when the cooling performance is lower than expected due to a malfunction of the fan or vent for cooling the inverter. may operate and stop water supply. When such overheat protection is activated and the water supply is stopped, normally, the retry function restarts water supply after the stop. However, unless the ambient temperature conditions and the inverter cooling performance improve, the overheat protection will operate again and the water supply will stop.

As a method of avoiding these, there is a method of using the inverter stall (current limit) function to lower the operating frequency of the pump so as not to lead to overheat protection. However, since the inverter stall function lowers the operating frequency, there is a problem that the pressure required for water supply cannot be generated and sufficient water supply cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is capable of reducing the probability of water supply being stopped due to overheat protection when restarting water supply after stopping water supply due to overheat protection of an inverter. An object is to provide a device, a control device and an inverter.

A water supply device according to a first aspect of the present invention includes a pump, an electric motor that drives the pump, and an inverter that has a plurality of switching elements and drives the electric motor at a variable speed, and A processor is provided externally, the processor compares a carrier wave with a sinusoidal signal as a voltage command for each phase to generate a switching signal, and supplies the generated switching signal to the plurality of switching elements, the processor and, when the pump is restarted after being stopped due to overheat protection, the carrier frequency of the carrier wave is lowered from before the stop at the timing after the restart.

According to this configuration, loss during on/off control of the switching element is reduced and heat generation is suppressed. Probability of outage can be reduced.

A water supply apparatus according to a second aspect of the present invention is the water supply apparatus according to the first aspect, wherein the processor restarts the restart according to the time from the start of operation of the pump to the stop of water supply due to overheat protection. Determines the carrier frequency after the hour.

According to this configuration, the carrier frequency is determined according to the time from the start of operation of the pump to the stoppage of water supply due to overheat protection.・Since loss during off control is further reduced and heat generation is further suppressed, the probability of water supply stop due to overheat protection can be reduced.

A water supply apparatus according to a third aspect of the present invention is the water supply apparatus according to the second aspect, wherein the processor detects that the shorter the time from the start of operation of the pump to the stoppage of water supply due to overheat protection, the faster the pump. Lower the carrier frequency when restarting after stopping overheat protection.

According to this configuration, the shorter the time from the start of operation of the pump until the water supply is stopped by the overheat protection, the higher the ambient temperature of the installation location, or the malfunction of the fan or vent for cooling the inverter. Cooling performance is worse than expected, but by lowering the carrier frequency after restarting, the probability of water supply stop due to overheat protection can be reduced.

A water supply apparatus according to a fourth aspect of the present invention is the water supply apparatus according to the first aspect, wherein the pump, the electric motor, and the inverter have a plurality of sets, and the processor controls the overheating protection of the pump. When the inverter is restarted after being stopped by , the carrier frequency of the carrier wave of each of the inverters is lowered from that before the stop at the timing after the restart.

According to this configuration, the loss during on/off control of the switching element is reduced and heat generation is suppressed, so the probability of water supply stop due to overheat protection can be reduced.

A water supply device according to a fifth aspect of the present invention is the water supply device according to the first aspect, wherein the pump has a first pump and a second pump, and the processor When the overheat protection of the first pump is stopped before the pump is driven, the operating frequency exceeds a preset frequency while the first pump and the second pump are operating in parallel after that. In this case, the carrier frequency of the carrier wave is lowered from the normal carrier frequency.

According to this configuration, the loss during on/off control of the switching element is reduced and heat generation is suppressed, so the probability of water supply stop due to overheat protection can be reduced.

A water supply apparatus according to a sixth aspect of the present invention is the water supply apparatus according to the fifth aspect, wherein the processor causes overheat protection of the first pump to operate before the second pump is activated. , when restarting the first pump, if the operating frequency of the first pump reaches an operating frequency lower than the normal operating frequency at which the second pump is added, the second pump is started and the operating frequency of the first pump is lowered.

According to this configuration, by lowering the operating frequency before the overheat protection of the first pump operates again, the possibility that the overheat protection will operate again in the first pump is reduced, and the second pump operation can be started and the discharge flow rate can be secured.

A control device according to a seventh aspect of the present invention is a control device that controls an inverter that has a plurality of switching elements and variable-speed drives an electric motor that drives a pump, the control device comprising: wave signal to generate a switching signal, supply the generated switching signal to the plurality of switching elements, and when the pump is restarted after being stopped by overheat protection, at a timing after the restart, A processor is provided for lowering the carrier frequency of the carrier wave from before stopping.

According to this configuration, loss during on/off control of the switching element is reduced and heat generation is suppressed. Probability of outage can be reduced.

An inverter according to an eighth aspect of the present invention is an inverter that has a plurality of switching elements and variable-speed drives an electric motor that drives a pump, and compares a carrier wave with a sine wave signal that is a voltage command for each phase. to generate a switching signal, supply the generated switching signal to the plurality of switching elements, and when the pump is restarted after being stopped by overheat protection, the carrier frequency of the carrier wave is changed at the timing after restarting Equipped with a processor lower than before stopping.

According to this configuration, loss during on/off control of the switching element is reduced and heat generation is suppressed. Probability of outage can be reduced.

According to one aspect of the present invention, loss during on/off control of the switching element is reduced and heat generation is suppressed. The probability of water supply interruption due to protection can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram of the water supply apparatus which concerns on 1st Embodiment. 1 is a schematic configuration diagram of an inverter according to a first embodiment; FIG. FIG. 3 is a diagram showing an example of time-series changes of a sine wave signal, a carrier wave, and switching signals supplied to switching elements S1 and S2, which are phase voltage commands; It is a schematic block diagram of the water supply apparatus which concerns on 2nd Embodiment. FIG. 10 is a diagram showing changes in operating frequency after overheat protection is activated in Control Example 2 of the second embodiment;

Hereinafter, each embodiment will be described with reference to the drawings. However, more detailed description than necessary may be omitted. For example, detailed descriptions of well-known matters and redundant descriptions of substantially the same configurations may be omitted. This is to avoid unnecessary verbosity in the following description and to facilitate understanding by those skilled in the art.

<First embodiment>
In the first embodiment, if the ambient temperature of the place where the water supply device is installed is higher than expected, or if the cooling performance is worse than expected due to a problem with the fan or vent for cooling the inverter, the inverter After the overheat protection of , and the supply of water is stopped, the retry function of the inverter restarts, after the restart, operation is performed at a carrier frequency lower than the carrier frequency during normal operation.

As a result, when restarting with the retry function of the inverter, by operating at a carrier frequency lower than the carrier frequency of the carrier wave during normal operation, unpleasant magnetic noise is generated during operation, but the switching element is turned on.・Since loss during off control is reduced and heat generation is suppressed, the probability of water supply stop due to overheat protection can be reduced.

FIG. 1 is a schematic configuration diagram of a water supply device according to a first embodiment. This water supply apparatus is a facility for supplying tap water mainly to single-family houses, condominiums, office buildings, commercial facilities, or buildings (to be supplied with water) such as schools.
As shown in FIG. 1, a suction port of a water supply device 30 of the pump facility 10 is connected through an introduction pipe 2 to a water pipe (water main) 1 or a water tank (not shown). A water supply pipe 7 is connected to an outlet of the water supply device 30, and the water supply pipe 7 communicates with a water tap (for example, a faucet) of each building. A pumping station 10 boosts the pressure of water from a water pipe (or water tank) and supplies water to each faucet (not shown) in the building.

The water supply device 30 includes a pump 20, an electric motor (hereinafter also referred to as a motor) 21 as a driving source for driving the pump 20, and an inverter 22 as a driving device having a plurality of switching elements and driving the electric motor 21 at variable speeds. and has. Further, the water supply device 30 includes a check valve 23, a flow switch 24, a pressure sensor 26, a pressure tank 28, and a control device 40 that controls the inverter 22 on the discharge side (downstream side) of the pump 20. . It should be noted that the electric motor 21 and the inverter 22 may be configured as an integrated pump device that is integrally connected, and the control device 40 may be integrated.

The check valve 23 is provided in a discharge pipe (discharge portion) 32 connected to the discharge port of the pump 20, and prevents backflow of water when the pump 20 stops. A flow switch 24 is provided on the downstream side (secondary side) of the check valve 23 . The flow switch 24 is a flow rate detector that detects that the flow rate of water flowing through the discharge pipe 32 has decreased to a predetermined value, that is, an insufficient amount of water.

Further downstream of the flow switch 24 in the discharge pipe 32, a pressure sensor 26 and a pressure tank 28 are provided. The pressure sensor (first pressure sensor) 26 is a pressure measuring device for measuring the discharge side pressure of the pump 20 (hereinafter, the discharge side pressure indicates the pressure value measured by the pressure sensor 26). The pressure tank 28 is a pressure retainer for holding the discharge side pressure while the pump 20 is stopped.

The control device 40 has a storage unit 41 and a processor 42 . The storage unit 41 stores programs to be executed by the processor 42 . In addition to the function to control the inverter, the program includes a water supply operation that starts the pump 20 when the pressure on the discharge side of the pump 20 drops and raises the pressure on the discharge side to a predetermined pressure, and a water supply operation on the discharge side of the pump. It is also equipped with a pump operation control function that stops the pump when the amount of water used decreases and the amount of water becomes small. Processor 42 controls inverter 22 .
Note that the storage unit 41 and the processor 42 may perform both the pump operation control function and the inverter control function with one storage unit and processor as described above, or the storage unit and processor may be used for each control. You may prepare.

FIG. 2 is a schematic configuration diagram of the inverter according to the first embodiment. As shown in FIG. 2 , the inverter 22 includes a converter 221 that rectifies an input voltage, a DC voltage storage unit 222 that stores DC voltage, and a DC/AC converter 223 that is connected to the electric motor 21 . The DC-AC converter 223 converts the DC voltage accumulated in the DC voltage accumulation unit 222 into an AC voltage, and supplies the converted three-phase AC voltage to the electric motor 21 .

Converter 221 is connected to power supply 31 . For example, the converter 221 has a diode D11 whose anode is connected to the first phase of the power supply 31 and a diode D12 whose cathode is connected to the diode D11.

Converter 221 further comprises a diode D13 whose cathode is connected to the cathode of diode D11 and whose anode is connected to the second phase of power supply 31, and whose cathode is connected to the anode of diode D13 and whose anode is diode D12. has a diode D14 connected to the anode of .

Converter 221 further comprises a diode D15 whose cathode is connected to the cathode of diode D13 and whose anode is connected to the third phase of power supply 31, and whose cathode is connected to the anode of diode D15 and whose anode is diode D14. has a diode D16 connected to the anode of .

As an example, the DC voltage storage unit 222 is a capacitor C having one end connected to the cathode of the diode D15 and the other end connected to the anode of the diode D16.

The DC/AC converter 223 has switching elements S1, S2, S3, S4, S5 and S6 and diodes D1, D2, D3, D4, D5 and D6. Here, as an example, the switching elements S1, S2, S3, S4, S5, and S6 are n-type transistors. Note that the switching elements S1, S2, S3, S4, S5, and S6 may be MOSFETs.

Switching element S1 has a base connected to processor 42 and supplied with a switching signal, a collector connected to one end of capacitor C, and an emitter connected to the first phase of motor 21 . The diode D1 has a cathode connected to the collector of the switching element S1 and an anode connected to the emitter of the switching element S1.

The switching element S2 has a base connected to the processor 42 and supplied with a switching signal, a collector connected to one end of the capacitor C, and an emitter connected to the other end of the capacitor C. The diode D2 has a cathode connected to the collector of the switching element S2 and an anode connected to the emitter of the switching element S2.

Switching element S3 has a base connected to processor 42 and supplied with a switching signal, a collector connected to one end of capacitor C, and an emitter connected to the second phase of motor 21 . The diode D3 has a cathode connected to the collector of the switching element S3 and an anode connected to the emitter of the switching element S3.

The switching element S4 has a base connected to the processor 42 and supplied with a switching signal, a collector connected to one end of the capacitor C, and an emitter connected to the other end of the capacitor C. The diode D4 has a cathode connected to the collector of the switching element S4 and an anode connected to the emitter of the switching element S4.

The switching element S5 has a base connected to the processor 42 and supplied with a switching signal, a collector connected to one end of the capacitor C, and an emitter connected to the third phase of the motor 21 . The diode D5 has a cathode connected to the collector of the switching element S5 and an anode connected to the emitter of the switching element S5.

The switching element S6 has a base connected to the processor 42 and supplied with a switching signal, a collector connected to one end of the capacitor C, and an emitter connected to the other end of the capacitor C. The diode D6 has a cathode connected to the collector of the switching element S6 and an anode connected to the emitter of the switching element S6.

FIG. 3 is a diagram showing an example of time-series changes of a sine wave signal, a carrier wave, and switching signals supplied to the switching elements S1 and S2, which are voltage commands for each phase. FIG. 3 shows the waveform W1 of the sine wave signal, the waveform W2 of the carrier wave, the waveform W3 of the switching signal supplied to the switching element S1, and the waveform W4 of the switching signal supplied to the switching element S2. As shown by the waveform W3 in FIG. 3, the switching signal supplied to the switching element S1 is at a high level when the voltage of the sine wave signal is higher than the voltage of the carrier wave, and at a high level when the voltage of the sine wave signal is lower than the voltage of the carrier wave. , goes low. Conversely, as shown by waveform W4 in FIG. 3, the switching signal supplied to switching element S2 is at a low level when the voltage of the sine wave signal is higher than the voltage of the carrier wave, and when the voltage of the sine wave signal is higher than the voltage of the carrier wave. If it is lower, it becomes a high level.

The switching signal supplied to switching element S3 is 120 degrees out of phase with the switching signal supplied to switching element S1, and similarly the switching signal supplied to switching element S4 is the switching signal supplied to switching element S2. 120 degrees out of phase with the signal. The switching signal supplied to switching element S5 is further 120 degrees out of phase with the switching signal supplied to switching element S3, and similarly the switching signal supplied to switching element S6 is supplied to switching element S4. It is also 120 degrees out of phase with the switching signal.

The processor 42 compares the carrier wave and the sinusoidal signal as the voltage command for each phase to generate a switching signal, and supplies the generated switching signal to the plurality of switching elements S1 to S6. When the pump 20 is restarted after being stopped due to overheat protection, the processor 42 lowers the carrier frequency of the carrier wave from before the stop at the timing after the restart. Here, the timing is, for example, when the pump is restarted. As a result, loss during ON/OFF control of the switching elements S1 to S6 is reduced and heat generation is suppressed, so the probability of water supply stop due to overheat protection can be reduced.

At that time, the processor 42 may determine the carrier frequency after the restart according to the time from the start of operation of the pump 20 to the stoppage of water supply due to overheat protection. Specifically, for example, the processor 42 may lower the carrier frequency after the restart as the time from the start of operation of the pump to the stoppage of water supply due to overheat protection is shorter. As a result, the shorter the time from the start of operation of the pump to the stoppage of water supply by overheat protection, the higher the ambient temperature in the installation location, or the malfunction of the fan or vent for cooling the inverter, which is higher than expected. Cooling performance is poor, but by lowering the carrier frequency after restarting, the probability of water supply stop due to overheat protection can be reduced.

As described above, the water supply apparatus according to the first embodiment includes the pump 20, the electric motor 21 that drives the pump 20, the inverter 22 that has a plurality of switching elements and drives the electric motor 21 at variable speeds, and the processor 42. Prepare. The processor 42 compares the carrier wave and the sinusoidal signal as the voltage command for each phase to generate a switching signal, and supplies the generated switching signal to the plurality of switching elements S1 to S6. When the pump 20 is restarted after being stopped due to overheat protection, the processor 42 lowers the carrier frequency of the carrier wave from before the stop at the timing after the restart.

With this configuration, loss during on/off control of the switching elements S1 to S6 is reduced and heat generation is suppressed, so the probability of water supply stop due to overheat protection can be reduced.

<Second embodiment>
Next, a second embodiment will be described. FIG. 4 is a schematic configuration diagram of a water supply device according to a second embodiment. Elements that are the same as those in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted. In the example shown in FIG. 4, compared to FIG. 1, the water supply device 30b according to the second embodiment is provided with two sets of the pump 20, the electric motor 21, the inverter 22, the check valve 23, and the flow switch 24. They are different in that they are provided in parallel. By providing a plurality of pumps 20, when some of the pumps 20 become inoperable, water supply can be continued by the other operable pumps 20, thereby avoiding water interruption as much as possible.

The processor 42 of the control device 40 also controls two sets of inverters 22 . Hereinafter, one of the two sets of pumps 20 will be referred to as the first pump, and the other as the second pump.

<Control example 1>
Next, control example 1 when the pump is restarted after being stopped by overheat protection will be described. As in the first embodiment, the processor 42 sets the carrier frequency of the carrier wave of each inverter 22 (that is, all inverters 22) at the timing after the restart when the pump is restarted after being stopped due to overheat protection. lower than before stopping. Specifically, for example, the processor 42 lowers the carrier frequencies of the carrier waves of all the inverters to frequencies lower than normal when the pumps are restarted after being stopped due to overheat protection.

With this configuration, loss during on/off control of the switching elements S1 to S6 is reduced and heat generation is suppressed, so the probability of water supply stop due to overheat protection can be reduced.

<Control example 2>
Next, control example 2 in the case where the pump is restarted after being stopped by overheat protection will be described. Normally, the first pump operates, the operating frequency (rotational speed) increases, and when the operating frequency of the first pump reaches a predetermined frequency, the second pump is started and the two pumps operate in parallel. is done.

FIG. 5 is a diagram showing changes in the operating frequency after the overheat protection operation in Control Example 2 of the second embodiment. As shown in FIG. 5, the processor 42, for example, when restarting the first pump with the retry function if the overheat protection of the first pump was activated before the second pump was started, the first When the operating frequency of the pump reaches an operating frequency (second set frequency) F1 that is lower than the normal operating frequency (first normal frequency) for adding the second pump, the second pump is started and Lower the operating frequency of the first pump. As a result, before the overheat protection of the first pump operates again, the operating frequency is lowered, thereby reducing the possibility that the overheat protection of the first pump will operate again, while allowing the second pump to operate. It is possible to start and secure the discharge flow rate. Then, for example, when the operating frequencies of the first pump and the second pump become the same, the processor 42 changes the operating frequencies of the first pump and the second pump with the same time change as shown in FIG. raise.

Then, when the operating frequency exceeds a preset frequency F2 (or the output current exceeds a predetermined output current value) while the first pump and the second pump are operating in parallel, the carrier frequency of the carrier wave is changed to Lower than the preset carrier frequency for normal times. As a result, loss during ON/OFF control of the switching element is reduced and heat generation is suppressed, so the probability of water supply stop due to overheat protection can be reduced.

Three or more sets of pumps 20, electric motors 21, inverters 22, check valves 23, and flow switches 24 may be provided.

In each embodiment, the processor 42 has been described as being outside the inverter 22 , but the present invention is not limited to this, and the processor 42 may be provided inside the inverter 22 .

As described above, the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the present invention at the implementation stage. Further, various inventions can be formed by appropriate combinations of the plurality of constituent elements disclosed in the above embodiments. For example, some components may be omitted from all components shown in the embodiments. Furthermore, components across different embodiments may be combined as appropriate.

10, 10b Pump facility 20 Pump 21 Electric motor 22 Inverter 221 Converter 222 DC voltage storage unit 223 DC AC converter 23 Check valve 24 Flow switch 26 Pressure sensor 28 Pressure tank 30, 30b Water supply device 31 Power supply 32 Discharge pipe 40 Control device 41 Storage unit 42 Processors D1 to D6, D11 to D16 Diodes S1 to S6 Switching elements

Claims (8)

a pump;
an electric motor that drives the pump;
an inverter having a plurality of switching elements and variable-speed driving the electric motor;
with
having a processor inside or outside the inverter;
The processor compares a carrier wave and a sine wave signal that is a voltage command for each phase to generate a switching signal, supplies the generated switching signal to the plurality of switching elements,
When the pump is restarted after being stopped due to overheat protection, the processor lowers the carrier frequency of the carrier wave from before the stop at a timing after the restart. The water supply apparatus according to claim 1, wherein the processor determines the carrier frequency after the restart according to the time from the start of operation of the pump to the stop of water supply due to overheat protection. The water supply device according to claim 2, wherein the processor lowers the carrier frequency when the pump is restarted after the overheat protection is stopped, as the time from the start of operation of the pump to the stop of the water supply by the overheat protection is shorter. The pump, the electric motor, and the inverter have a plurality of sets,
The water supplying apparatus according to claim 1, wherein when the pump is restarted after being stopped due to overheat protection, the processor lowers the carrier frequency of the carrier wave of each of the inverters from before the stop at a timing after the restart. the pump comprises a first pump and a second pump;
When the overheat protection of the first pump is stopped before the second pump is driven, the processor determines the operating frequency of the first pump and the second pump while the first pump and the second pump are operating in parallel after that. exceeds a preset frequency, the carrier frequency of the carrier wave is lowered below the normal carrier frequency. When the overheat protection of the first pump operates before the second pump is started, the processor sets the operating frequency of the first pump to the above-mentioned 6. The water supply system according to claim 5, wherein when an operating frequency lower than the normal operating frequency for adding a second pump is reached, the second pump is activated and the operating frequency of the first pump is reduced. A control device that controls an inverter that has a plurality of switching elements and that drives a motor that drives a pump at variable speeds,
A case where a switching signal is generated by comparing a carrier wave and a sine wave signal serving as a voltage command for each phase, the generated switching signal is supplied to the plurality of switching elements, and the pump is restarted after being stopped by overheat protection. A control device comprising a processor that lowers the carrier frequency of the carrier wave from before the stop at a timing after the restart in the above. An inverter that has a plurality of switching elements and variable-speed drives an electric motor that drives a pump,
A case where a switching signal is generated by comparing a carrier wave and a sine wave signal serving as a voltage command for each phase, the generated switching signal is supplied to the plurality of switching elements, and the pump is restarted after being stopped by overheat protection. The inverter provided with a processor that lowers the carrier frequency of the carrier wave from before the stop at a timing after restarting.

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