WO2015141235A1

WO2015141235A1 - Power sensor, power sensor system, and regenerated power detection device

Info

Publication number: WO2015141235A1
Application number: PCT/JP2015/001575
Authority: WO
Inventors: 浩章辻本
Original assignee: 公立大学法人大阪市立大学
Priority date: 2014-03-20
Filing date: 2015-03-20
Publication date: 2015-09-24
Also published as: JP6210606B2; JPWO2015141235A1

Abstract

This power sensor has a magnetic element that has a magnetic film, which is patterned in an oblique direction at a conductor, a first element terminal, which is connected to one end of the conductor, and a second element terminal, which is connected to the other end of the conductor, and during measurement, the first element terminal is connected to the subject device that is the subject of power measurement. The power sensor has: a measurement resistor of which one end is connected to the second element terminal of the magnetic element; and a detector that detects the DC component of the voltage between the first element terminal and the second element terminal. The magnetic element is disposed in a manner such that the direction from the first element terminal to the second element terminal during measurement is approximately parallel to the wire connected to the subject device.

Description

Power sensor, power sensor system, and regenerative power detection device

The present invention relates to a regenerative power detection device that detects generation of regenerative power and outputs a notification signal notifying that regenerative power has been generated in order to effectively use regenerative power generated by an electric motor.

An electric motor is widely used as a device that converts electric power into rotational motion. In particular, it is frequently used as a driving device for wheels such as automobiles and trains. When the electric motor is used as a vehicle propulsion device, electric power returns from the electric motor to the driving side when braking the vehicle body. Many methods for effectively using regenerative power when this power regeneration is performed have been proposed.

For example, Patent Document 1 discloses a power regeneration system that recovers regenerative power generated by an electric motor during regenerative braking. Here, whether or not the entire system shifts to the regenerative operation is determined based on the operation of the drive operation device such as an accelerator or a brake.

In Patent Document 2, when processing regenerative power, a capacitor is placed between wires that supply power to an inverter circuit that sends drive current to the motor, and it is determined that the regenerative operation has started when the voltage across the capacitor rises. An apparatus for passing a current through a regenerative resistor in a regenerative circuit is disclosed.

JP 2013-207976 A JP 2010-110139 A

When controlling the processing of regenerative power based on the operation of the operating device as in Patent Document 1, it is not necessarily detected whether or not the motor actually generates regenerative power. Moreover, in the case of patent document 2, only the influence which regenerative electric power has on a direct current element is seen. If it is possible to directly detect whether or not the motor actually generates regenerative power, it becomes possible to collect and use the regenerative power more finely.

The present invention has been conceived in view of the above problems, and directly detects the generation of regenerative power of a motor by detecting whether the power consumption of the motor is positive or negative using a wattmeter using the magnetoresistive effect. A regenerative power detection device is provided.

More specifically, the regenerative power detection device of the present invention is:
A power sensor unit provided on the connection between the drive device (inverter) and the electric motor;
A controller that is connected to the power sensor unit and that outputs a notification signal notifying that regenerative power has been generated when the power sensor unit indicates that power consumption in the motor has become negative. And

The regenerative power detection apparatus according to the present invention can be formed very thin and small because the power sensor unit uses a magnetic film. Therefore, even if it is incorporated in a relatively small drive system, the weight does not increase and the bulk does not increase.

The power sensor unit used in the present invention can directly measure power consumption and regenerative power. Therefore, in a system using a battery, it is useful for managing the residual power of the battery.

It is a figure which shows the structure of the regenerative electric power detection apparatus which concerns on this invention. It is a figure which shows the structural example of the electric power sensor unit of a regenerative electric power detection apparatus. It is a figure which shows the other structural example of an electric power sensor unit. It is a figure explaining the principle of an electric power sensor. It is a figure explaining phase difference. It is a figure which shows the relationship between a phase difference and the output of a power sensor.

Hereinafter, the regenerative power detection apparatus according to the present invention will be described with reference to the drawings. In addition, the following invention demonstrates one Embodiment of this invention, and this invention is not limited to the following description. The following embodiments can be modified without departing from the spirit of the present invention.

FIG. 1 shows a configuration diagram of a regenerative power detection device 10 according to the present invention. The regenerative power detection device 10 includes a power sensor unit (power sensor system) 12 and a controller 14. The regenerative power detection device 10 is incorporated between the electric motor 22 and the driving device 24 of the electric motor system 20 including the electric motor 22, the driving device 24, and the battery 26. The controller 14 of the regenerative power detection device 10 outputs a notification signal Sa that notifies that regenerative power is generated. This notification signal Sa can be used for various purposes. Here, the case where it uses as a control signal of the switch 28 provided between the drive device 24 and the regenerative electric power detection apparatus 10 is demonstrated.

The battery 26 is a power source in the electric motor system 20. Electric power is sent from the battery 26 to the driving device 24 through connection lines L26a and L26b. The drive device 24 is an inverter device. Therefore, the inverter circuit 24a which converts direct current into three-phase alternating current and the drive controller 24b which controls the inverter circuit 24a are included.

3 phase alternating current is supplied from the drive unit 24 to the motor 22. Here, three connections L24a, L24b, and L24c are used. The electric motor 22 is a so-called motor. The switcher 28 is disposed between the driving device 24 and the electric motor 22. The switcher 28 can switch between a path (L24a, L24b, L24c) from the driving device 24 toward the electric motor 22 and a path (L28a, L28b, L28c) toward which the regenerative power from the electric motor 22 is directed toward the battery 26. The specific configuration of the switch 28 is not particularly limited.

A rectifier 30 is disposed between the switch 28 and the battery 26. The rectifier 30 rectifies the regenerative power generated by the electric motor 22 into direct current. Further, when the rectified power does not reach a voltage that can charge the battery 26, a device for boosting the voltage may be included. The rectifier 30 to the battery 26 are connected by wirings L30a and L30b.

FIG. 2 shows an enlarged view of the power sensor unit 12. In the power sensor unit 12,

power sensors

40 a, 40 b and 40 c are arranged for each of the three connections L 24 a, L 24 b and L 24 c from the driving device 24. Each power sensor includes

magnetic elements

42a, 42b, 42c, measuring

resistors

43a, 43b, 43c,

amplifiers

44a, 44b, 44c, and low-

pass filters

45a, 45b, 45c. The power sensor unit 12 has an adder 48 that adds the outputs of the low-

pass filters

45a, 45b, and 45c.

The

magnetic elements

42a, 42b, and 42c are strip-like magnetic films. The

measurement resistors

43a, 43b, and 43c are resistors having a large resistance value for allowing a constant current to flow through the

magnetic elements

42a, 42b, and 42c. One end of each of the

magnetic elements

42a, 42b, and 42c is connected to the connection lines L24a, L24b, and L24c.

The other end of the

magnetic elements

42a, 42b, 42c and one end of the

measuring resistors

43a, 43b, 43c are connected in series. The other ends of the

measurement resistors

43a, 43b, and 43c are grounded. Further, both ends of the

magnetic elements

42a, 42b, and 42c are connected to

amplifiers

44a, 44b, and 44c. The outputs of the

amplifiers

44a, 44b, 44c are connected to low-

pass filters

45a, 45b, 45c, respectively.

The

magnetic elements

42a, 42b, 42c are arranged so that the longitudinal direction of the strip shape matches the direction in which the current of the wiring flows. By connecting the

magnetic elements

42a, 42b, 42c and the measuring

resistors

43a, 43b, 43c in this way, it is possible to measure the power consumption at the load to which each wiring is connected, as will be described later (described in FIG. 4). it can.

Each power consumption is an output of the low-

pass filters

45a, 45b, 45c. In the case of three-phase AC, the power consumption is basically expressed as the sum of the power consumption of each phase. Therefore, the output of the adder 48 becomes the power consumption of the electric motor 22. The output of the adder 48 is a signal Sw. The signal Sw is sent to the controller 14 (see FIG. 1). The signal Sw is a result of measuring the power consumed by the electric motor 22 with a positive / negative sign.

FIG. 3 shows another configuration of the power sensor unit 12. In three-phase AC, power is often measured by the two-watt meter method. FIG. 3 shows a configuration when power is measured by the two wattmeter method.

Power sensors

40a and 40b are used. The configuration of the

power sensors

40a and 40b is the same as that in FIG. However, the other end of the measurement resistor 43a of the power sensor 40a is connected to the connection L24b, and the other end of the measurement resistor 43b of the power sensor 40b is connected to the connection L24c. The power sensor 40c is not used. As described above, the power sensor unit 12 may be configured with two power sensors.

Referring to FIG. 1 again, the operation of the regenerative power detection device 10 will be described. In the electric motor system 20, an instruction (not shown) is sent to the drive controller 24 b of the drive device 24. In response to this instruction, the driving device 24 converts the DC voltage of the battery 26 into three-phase AC for driving the electric motor 22.

The switch 28 allows electric power to flow from the driving device 24 to the electric motor 22. The electric motor 22 is driven by receiving a three-phase current from the driving device 24. At this time, the power sensor unit 12 measures the power consumed by the electric motor 22 as a positive value. This is notified to the controller 14 by the signal Sw of the adder 48 shown in FIG. While the controller 14 can determine that the electric motor 22 is consuming electric power based on the signal Sw from the electric power sensor unit 12, the notification signal Sa for securing the switch 28 from the driving device 24 to the electric motor 22. Is output.

On the other hand, when the motor 22 starts to regenerate power due to braking or the like, the power sensor unit 12 observes that negative power is consumed by the motor 22. This signal is notified to the controller 14 as the signal Sw of the adder 48 shown in FIGS. When the controller 14 determines that the electric motor 22 has consumed negative power, the controller 14 transmits a notification signal Sa indicating the fact to the switch 28. In other words, when the value indicated by the signal Sw becomes negative, the controller 14 outputs the notification signal Sa notifying that the regenerative power has been generated. The switch 28 switches the wiring between the driving device 24 and the electric motor 22 so that the electric motor 22 and the rectifier 30 are connected. That is, it is possible to detect that the electric motor 22 has started to perform power regeneration without using an operation on the driving device 24.

When the electric motor 22 starts power regeneration, it is connected to the rectifier 30 via the switch 28, so that the regenerative power from the electric motor 22 is rectified by the rectifier 30 and becomes direct current. The rectifier 30 charges the battery 26. If the DC power rectified by the rectifier 30 does not become a voltage that can charge the battery 26, the voltage may be boosted.

When the electric motor 22 stops power regeneration and starts powering, the power sensor unit 12 observes that the electric motor 22 consumes positive electric power. Therefore, the signal Sw is notified to the controller 14 that the power consumption is positive (the electric motor 22 is consuming power). When the controller 14 determines that the electric motor 22 has consumed positive power, the controller 14 transmits a notification signal Sa indicating the fact to the switch 28. The switcher 28 switches so that the drive device 24 and the electric motors 22 are connected.

FIG. 4 illustrates the operating principle of the power sensor 40. Here, in order to simplify the description, a case of a single phase will be described. The power sensor 40 includes a magnetic element 42, a measurement resistor 43, and a detector 27. The detector 27 detects the DC component of the voltage between the element terminal 143 and the element terminal 144. For example, the detector 27 includes an amplifier 44 and a low-pass filter 45. The magnetic element 42 and the measurement resistor 43 that constitute the power sensor 40 are connected in series. Then, the load 92 connected to the power source 91 of the circuit under measurement 90 is connected in parallel. The load 92 is for one phase of the electric motor 22. The connection point of the power sensor 40 is the

connection terminals

12a and 12b.

The magnetic element 42 is obtained by forming a magnetic film 142 on a substrate and patterning it with a conductor in an oblique direction. It is called a barber pole type.

Element terminals

143 and 144 are provided at both ends of the magnetic element 42 and connected to the amplifier 44. That is, the magnetic element 42 has a magnetic film 142 patterned in a diagonal direction with a conductor, an element terminal 143 connected to one end of the conductor, and an element terminal 144 connected to the other end of the conductor. . The amplifier 44 has a first input connected to the element terminal 143 and a second input connected to the element terminal 144, and amplifies the voltage between the element terminal 143 and the element terminal 144. The input of the low-pass filter 45 is connected to the output of the amplifier 44.

The magnetic element 42 is disposed adjacent to and parallel to the electric wire 93 a connecting the power source 91 and the load 92. Here, “parallel” means that the in-plane direction of the magnetic element 42 is parallel to a coaxial magnetic field formed around the electric wire 93a. In addition, the measurement resistor 43 is sufficiently large with respect to the resistance value R _mr of the magnetic element 42. Moreover, the resistance of the electric wire 93a is sufficiently small.

First, when the power supply 91 is a direct current, and the current flowing through the electric wire 93a, to 93b and I _1, the external magnetic field H applied to the magnetic element 42, as a proportionality constant alpha, is expressed by the equation (1) .
H = αI ₁ (1)

Since the change ΔR _mr of the electrical resistance of the magnetic element 42 is proportional to the externally applied magnetic field H, the proportionality constant is β, and the equation (1) is considered as expressed by the equation (2).
ΔR _mr = βH = β (αI ₁ ) (2)

_Assuming that the electric resistance when the external magnetic field H is not applied to the magnetic film 142 (operating point) is R _m0 , the electric resistance R _{m of the} entire magnetic element 42 when the external magnetic field H is applied is expressed by equation (3). It is expressed as
R _m = R _m0 + ΔR _mr = R _m0 + αβI ₁ (3)

That is, a magnetic film 142 which is disposed close to the electric wire 93a of the current I ₁ flows, has an electrical resistivity characteristics, such as (3). When the current I ₂ flows between the

element terminals

143 and 144 of the magnetic element 42, the voltage V _mr between the

element terminals

143 and 144 is expressed by the equation (4).
V _mr = R _m I ₂ = (R _m0 + ΔR _m ) I ₂ = (R _m0 + αβI ₁ ) I ₂ (4)

Then if V ₁ the voltage V _in Since the power source 91 is a DC, is expressed as equation (5). Then, the electric wire 93a, the resistance of the 93b is sufficiently small, and the resistance _{R m} also measuring resistor 43 of the magnetic element 42 (the value _{R 2)} is sufficiently smaller than. When the resistance of the load 92 and _{R 1,} the current _{I 1} flowing through the electric wire 93a, a current _{I 2} flowing through the magnetic element 42, respectively (6), so that the equation (7).

Therefore, the voltage V _mr between the

element terminals

143 and 144 of the magnetic element 42 is expressed as in equation (8). In addition, the relationship of R _m0 << R ₂ was used in the middle of the transformation of the formula (8). The _{K 1} is a proportionality constant. From the result of the equation (8), between the

element terminals

143 and 144 of the magnetic element 42, the voltage proportional to the power I ₁ V ₁ consumed by the load 92, the operation of the measuring resistor 43 (R ₂ ), and the magnetic element 42 are obtained. When the electrical resistance R _m0 at a point is determined, a uniquely determined sum of bias voltages can be obtained.

Such a relationship is established even when the power source 91 is AC. Next, the case where the power source 91 is alternating current and the load 92 is reactance will be described. The relationship between the equations (1) to (4) is as described above. Since the power supply 91 is AC, the voltage V _in is expressed as shown in Equation (9) when the amplitude is V ₁ and the angular frequency is ω. Further, since the load 92 in the measuring circuit 90 is reactance current _{I 1} flowing through the load 92, the phase shift occurs between the power supply 91 (voltage _{V in).} Let this phase shift be θ. On the other hand, since the magnetic element 42 is a normal resistor, it is in phase with the power source 91 (voltage V _in ). Therefore, the currents I ₁ and I ₂ are expressed as in the equations (10) and (11).

Therefore, if the expressions (10) and (11) are substituted into the expression (4), it is transformed as the expression (12).

Referring to equation (12), it can be seen that the final term shows the active power consumed by the load 92 as a direct current component. That is, the DC voltage obtained by passing the output between the

element terminals

143 and 144 through the low-pass filter 45 is a voltage proportional to the active power consumed by the load 92.

Now, in this way, the power sensor 40 outputs a voltage proportional to the active power consumed by the load 92. Here, although the current consumed by the load 92 is delayed with respect to the voltage, when the load 92 generates power and a back electromotive force is generated, the phase between the voltage and the current is further increased. FIG. 5 is a graph schematically showing the relationship between the AC voltage applied for driving and the current flowing through the load.

The horizontal axis is the phase (degrees), and the vertical axis is the amplitude (normalized). Let θ be the phase difference between the voltage and current. FIG. 6 shows the relationship between the measured output of the power sensor 40 and the phase difference θ in the circuit of FIG. The horizontal axis is the phase difference angle (degrees), and the vertical axis is the output value of the power sensor 40. Although θ shows a positive value up to 90 degrees, the output value of the power sensor 40 becomes negative when θ exceeds 90 degrees. This shows a state where the back electromotive force is generated just at the load 92.

Thus, the power sensor 40 outputs a negative value when a back electromotive force is generated. Therefore, when the electric motor 22 in FIG. 1 starts power regeneration, it can be detected by the sign of the power sensor 40.

In the present invention, an apparatus for detecting regenerative power for driving an electric motor has been described. However, even in a reverse power flow in which a power generated by a consumer using a solar panel or the like is returned between the power plant and the consumer to the power plant side. The present invention can be used.

The regenerative power detection device according to the present invention can be widely used for driving an electric motor with an inverter.

10 Regenerative power detection device 12 Power sensor unit (power sensor system)
DESCRIPTION OF SYMBOLS 14 Controller 20 Electric motor system 22 Electric motor 24 Drive device 26 Battery 27 Detector 28 Switcher 24a Inverter circuit 24b Drive controller 30 Rectifier 40

Electric power sensor

40a, 40b, 40c Electric power sensor 42

Magnetic element

42a, 42b, 42c Magnetic element 43

Measurement Resistance

43a, 43b, 43c Measuring resistance 44

Amplifier

44a, 44b, 44c Amplifier 45 Low-

pass filter

45a, 45b, 45c Low-pass filter 48 Adder 90 Circuit under measurement 91 Power supply 92

Load

12a,

12b Connection terminal

93a,

93b Electric wire

143, 144 Element Terminals L26a, L26b Connection L24a, L24b, L24c Connection L30a, L30b

Claims

A magnetic film patterned obliquely with a conductor; a first element terminal connected to one end of the conductor; and a second element terminal connected to the other end of the conductor; A magnetic element connected to a target device whose power is to be measured when the first element terminal is measured;
A measuring resistor having one end connected to the second element terminal of the magnetic element;
A detector for detecting a DC component of a voltage between the first element terminal and the second element terminal;
With
The magnetic element is a power sensor arranged so that a direction from the first element terminal to the second element terminal is substantially parallel to an electric wire connected to the target device during measurement.
The detector is
A first input is connected to the first element terminal, a second input is connected to the second element terminal, and a voltage between the first element terminal and the second element terminal is amplified. With an amplifier to
A low pass filter whose input is connected to the output of the amplifier;
A power sensor according to claim 1.
The magnetic film has a strip shape,
The power sensor according to claim 1, wherein the magnetic element is disposed so that a longitudinal direction of the strip shape is substantially parallel to an electric wire connected to the target device.
The power sensor according to claim 1, wherein a resistance value of the measurement resistor is larger than a resistance value of the magnetic element.
A plurality of power sensors according to claim 1;
An adder that outputs a signal indicating an added value obtained by adding output values of the plurality of power sensors;
With
The magnetic sensor provided in each of the plurality of power sensors is a power sensor system arranged so as to be substantially parallel to different wires among the plurality of wires connected to the target device during measurement.
The plurality of power sensors includes a first power sensor and a second power sensor,
In the first power sensor, the first element terminal is connected to a first output of the target device, and the other end of the measurement resistor is connected to a second output of the target device. The magnetic element is arranged so that a direction from the first element terminal to the second element terminal is substantially parallel to an electric wire connected to the first output of the target device,
The second power sensor has a first element terminal connected to the second output of the target device, and the other end of the measurement resistor connected to a third output of the target device. 6. The magnetic element is sometimes arranged such that a direction from the first element terminal to the second element terminal is substantially parallel to an electric wire connected to the second output of the target device. The power sensor system described in 1.
The number of the power sensors is three,
The power sensor system according to claim 5, wherein the other end of the measurement resistor is connected to ground during measurement.
A power sensor system according to claim 5;
A controller that outputs a notification signal notifying that regenerative power has been generated when a value indicated by a signal output by the power sensor system is negative;
A regenerative power detection device.