However, in the foregoing manner of performing detection by leading out the electrical connection point, when the current detection apparatus performs current detection, a detection location is limited by the electrical connection point disposed on the detected cable. In addition, after the electrical connection point is disposed, production compliance and insulation of the cable and a distance relationship between the electrical connection point and the power supply of the current detection apparatus further need to be considered. In addition, in the manner of performing detection by leading out the electrical connection point, the voltage divider resistor circuit or the step-down transformer is inevitably disposed to reduce the current on the detected cable for ease of detection. Therefore, the voltage divider resistor circuit or the step-down transformer further increases a volume and costs of the current detection apparatus, thereby bringing inconvenience to detection personnel.

In view of this, to further improve the current detection apparatus and reduce costs, the current detection apparatus is simplified, so that the detection personnel can detect the alternating current in a non-contact electrical connection manner. In the following embodiment, an example of detecting a detected cable that transmits a single-phase alternating current is used for description. However, a current detection apparatus described in the following embodiment may also be applicable to detection of a three-phase current. In the foregoing scenario, a method for using a current detection apparatus is only a simple combination in a single-phase scenario, and details are not described herein. FIG. 3 shows a current detection apparatus. The current detection apparatus 300 includes a first transformation unit 301, a power supply unit 302, a current detection unit 303, and a processing unit 304.

The following describes a function of each unit in a process in which the apparatus detects a current flowing through a detected cable.

The first transformation unit 301 includes a hollow part, the detected cable passes through the hollow part, and the first transformation unit 301 is configured to generate a first induction electrical parameter and a second induction electrical parameter based on an actual current flowing through the detected cable. The power supply unit 302 is connected to the first transformation unit 301, and is configured to: convert a voltage in the first induction electrical parameter into a first voltage, and transmit the first voltage to the processing unit 304 to supply power to the processing unit 304. The current detection unit 303 is connected to the first transformation unit 301, and is configured to: receive the second induction electrical parameter, convert a current in the second induction electrical parameter into a second voltage, and transmit the second voltage to the processing unit 304.

The processing unit 304 is separately connected to the power supply unit 302 and the current detection unit 303, and is configured to calculate a current value on the detected cable based on the second voltage that is output by the current detection unit 303. An induction electrical parameter may include a current and a voltage.

The first transformation unit 301 may specifically generate, by using the actual current flowing through the detected cable, the induction electrical parameter used by a subsequent device to perform current measurement. The induction electrical parameter is obtained by using the transformation unit, instead of being directly led out from the detected cable, thereby eliminating a limitation imposed by an electrical connection point on an installation location of the current detection apparatus 300, and increasing a production compliance level of the current detection apparatus 300 very well. For a specific current detection manner, refer to content described in the following embodiment.

Specifically, the first transformation unit 301 may include an open measuring type current transformer (CT). The current transformer includes a hollow part, and the detected cable passes through the hollow part. The current transformer is an instrument that converts, according to an electromagnetic induction principle, a high current flowing through the detected cable into a low current for measurement. The current transformer includes a ring-shaped magnetic core and a winding wound around the ring-shaped magnetic core. The ring-shaped magnetic core is equivalent to a primary side winding of the current transformer, and the winding wound around the ring-shaped magnetic core is a secondary side winding of the current transformer. A corresponding induction electrical parameter is generated on the secondary side winding of the current transformer according to the electromagnetic induction principle. Specifically, when the current flows through the detected cable, a magnetic field is generated around the detected cable. The magnetic field causes a change in a magnetic field in the ring-shaped magnetic core, and the first induction electrical parameter and the second induction electrical parameter are generated on the winding wound around the ring-shaped magnetic core.

As shown in FIG. 4, the power supply unit 302 includes a regulator circuit and an energy storage unit. Because a single-phase alternating current flows through the detected cable, an amplitude of a voltage and an amplitude of a current in the single-phase alternating current both change with time. To ensure power supply stability, the regulator circuit may convert a voltage whose amplitude changes in the first induction electrical parameter into a first voltage whose amplitude basically remains unchanged, and output the first voltage to the processing unit.

During specific implementation, the energy storage unit may include one or more capacitors connected in parallel.

It should be understood that, in a process in which the power supply unit 302 provided in this embodiment of this application is configured to supply power to the processing unit 304 and another load, as electric energy of the processing unit 304 is consumed, an input voltage of the regulator circuit gradually deviates from a working voltage range of the processing unit 304. To ensure normal working of the processing unit to a maximum extent, the energy storage unit is connected between the regulator circuit and the processing unit, and the energy storage unit may store the first voltage that is output by the regulator circuit, to ensure that a voltage that is output by the energy storage unit keeps stable at the first voltage for a long time. Therefore, the voltage that is output is effectively prevented from rapidly decreasing in a process of supplying power to a device connected to a backend of the power supply unit.

It should be understood that, because the single-phase alternating current flows through the detected cable, the voltage that is in the first induction electrical parameter and that is received by the power supply unit 302 is an alternating current voltage, and the device connected to the backend of the power supply unit 302 is a direct current power supply device in most cases. Therefore, the power supply unit 302 may further include an alternating current (AC)-to-direct current (DC) converter (AC/DC converter) connected between the regulator circuit and the first transformation unit 301. The AC/DC converter may be configured to: convert the alternating current voltage in the first induction electrical parameter into a direct current voltage, and output the direct current voltage to the regulator circuit.

As shown in FIG. 5, the current detection unit 303 includes a first resistor R1 and a current sampling circuit. When the current in the second induction electrical parameter flows through the first resistor R1, a corresponding voltage is generated at two ends of the first resistor R1. The current sampling circuit samples the voltage at the two ends of the first resistor R1, and outputs the sampled voltage to the processing unit 304.

The processing unit 304 may be a processor or a controller, for example, may be a general-purpose central processing unit (CPU), a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or another programmable logic device, a transistor logic device, a hardware component, or any combination thereof. The processing unit 304 may implement or execute various example logical blocks, modules, and circuits described with reference to content disclosed in this application. The foregoing processing unit 304 may alternatively be a combination implementing a computing function, such as a combination including one or more microprocessors, or a combination of a DSP and a microprocessor. In addition, the processing unit 304 may further include an ADC, configured to convert an analog parameter that is input by the current detection unit 303 into a digital parameter.

After receiving the voltage that is output by the current detection unit 303, the processing unit 304 may determine, by using the ADC, a valid value of the voltage that is output by the current detection unit 303, and perform an ohmic operation by using a resistance value of the first resistor R1, to obtain the current value on the detected cable. When the current detection unit 303 performs current detection, a sampled current and the actual current on the detected cable are reduced by a ratio (a ratio of a quantity of coil turns of the primary side winding to a quantity of coil turns of the secondary side winding of the current transformer). Therefore, after the second voltage is output, the processing unit 304 amplifies the current value by a cable current amplification factor by using the current value obtained through the ohmic operation, so that an actual current value on the detected cable can be obtained.

In a possible implementation, FIG. 6 is a schematic diagram of a structure of a first transformation unit 301. The first transformation unit 301 includes: a ring-shaped magnetic core, and a first winding T1 and a second winding T2 that are wound around the ring-shaped magnetic core. The detected cable passes through a hollow part of the ring-shaped magnetic core, two endpoints of the first winding form a first input port of the first transformation unit, and two endpoints of the second winding form a second output port of the first transformation unit.

In a possible implementation, the ring-shaped magnetic core is of a closed or non-closed ring-shaped hollow structure. The ring-shaped magnetic core is made of a metal material, and the metal material may be copper, aluminum, or the like. The detected cable passes through the hollow part of the ring-shaped magnetic core, and the ring-shaped magnetic core is configured to: generate a first induction electrical parameter on the first winding and a second induced voltage on the second winding based on an actual current on the detected cable.

A connection relationship between devices in the first transformation unit 301 shown in FIG. 6 may be as follows: The detected cable passes through the hollow part of the ring-shaped magnetic core, the two endpoints of the first winding T1 are connected to two input ports of the power supply unit 302, and the two endpoints of the second winding T2 are connected to two input ports of the current detection unit 303.

When the first transformation unit 301 shown in FIG. 6 is configured to generate the first induction electrical parameter and the second induction electrical parameter, an electromagnetic field is generated around the detected cable. When the detected cable passes through the hollow part of the ring-shaped magnetic core, a magnetic flux in the ring-shaped magnetic core is caused to change. A change in the magnetic flux causes the first induction electrical parameter to be generated on the first winding T1, and the second induction electrical parameter to be generated on the second winding T2. The first winding T1 outputs the generated first induction electrical parameter to the power supply unit 302, and the second winding T2 outputs the generated second induction electrical parameter to the current detection unit 303.

It should be noted that, because the first winding T1 and the second winding T2 in the first transformation unit 301 share one magnetic core, if the first winding T1 and the second winding T2 are both in a closed state to generate the induction electrical parameters, because a self-excitement phenomenon exists between the two windings, accuracy of a calculation result cannot be ensured when the current detection unit connected to a backend of the second winding T2 calculates current by using the second induction electrical parameter.

In view of this, a switch unit 305 is disposed between the first winding T1 and the power supply unit 302 and between the second winding T2 and the current detection unit 303. The switch unit 305 is configured to: connect the first winding T1 to the power supply unit 302, and connect the second winding T2 to the current detection unit 303. The switch unit 305 may be configured to enable the first winding T1 and the second winding T2 to be complementarily closed, so that impact, on detection of the generated induction electrical parameters, of self-excitement generated when the windings are both closed is effectively avoided.

Specifically, the switch unit 305 may include a first switch K1 and a second switch K2. As shown in FIG. 7, the first switch K1 is connected between the first winding T1 in the first transformation unit 301 and the power supply unit 302. The second switch K2 is connected between the second winding T2 in the first transformation unit 301 and the current detection unit 303.

Specifically, a first electrode of the first switch K1 is connected to a first endpoint of the first winding, and a second electrode of the first switch K1 is connected to a first endpoint on an input side of the power supply unit 302. A first electrode of the second switch K2 is connected to a second endpoint of the second winding, and a second electrode of the second switch K2 is connected to a second endpoint on an input side of the current detection unit 303. The first endpoint may be an end at which a device transmits a high-level voltage.

In a possible implementation, the current detection apparatus 300 may further include a controller connected to the switch unit.

During actual use, the switch unit 305 and the controller configured to control a working status of the switch unit 305 are both connected to the power supply unit 302, and the power supply unit 302 may supply power to the switch unit 305 and the controller.

Specifically, as shown in FIG. 8, the controller is separately connected to a control electrode of the first switch K1 and a control electrode of K2, and is configured to control the first switch and the second switch to be turned off and turned on.

In conclusion, as shown in a flowchart shown in FIG. 9, a method for controlling a status of a device in a switch unit by using the foregoing controller in an embodiment of this application mainly includes the following steps:

S901: Detect a first voltage that is output by a power supply unit.

S902: When it is determined that the first voltage is greater than or equal to a first preset threshold, disconnect a first transformation unit from the power supply unit, and connect the first transformation unit to a current detection unit, where the first preset threshold may be a maximum working voltage of a device connected to the power supply unit.

During actual use, a first control signal is sent to a first switch connected between the power supply unit and the first transformation unit, and a second control signal is sent to a second switch connected between the current detection unit and the first transformation unit. The first control signal is used to control the first switch to be turned on, and the second control signal is used to control the second switch to be turned off.

In an example, to ensure that the device connected to the power supply unit works normally, the first preset threshold may be less than the maximum working voltage.

S903: When it is determined that the first voltage is less than or equal to a second preset threshold, connect a first transformation unit to the power supply unit, and disconnect the first transformation unit from a current detection unit, where the second preset threshold may be a minimum working voltage of a device connected to the power supply unit.

During actual use, a third control signal is sent to a first switch connected between the power supply unit and the first transformation unit, and a fourth control signal is sent to a second switch connected between the current detection unit and the first transformation unit. The third control signal is used to control the first switch to be turned off, and the fourth control signal is used to control the second switch to be turned on.

Specifically, when the working statuses of the switches K1 and K2 in the switch unit provided in this embodiment of this application are controlled by using a method for controlling a current detection apparatus provided in this embodiment of this application, a waveform of an output voltage (Vout) of the power supply unit may be shown in FIG. 10. It can be learned from FIG. 10 that the output voltage of the power supply unit always falls within a working voltage range of the processing unit.

During actual use, switching moments of the two switches K1 and K2 may be delayed, to prevent the two switches from being both turned off and therefore avoid damage caused by a high voltage to the two switches or the power supply unit and the current detection unit that are connected to the two switches. Specifically, the working statuses of the switches K1 and K2 may be shown in FIG. 11.

It can be learned from the foregoing embodiment that, based on the current detection apparatus 300 provided in this embodiment of this application, the controller 405 may configure a turn-on moment of the first switch and a turn-on moment of the second switch in the switch unit based on an input voltage of the power supply unit. It can be learned with reference to the foregoing content that, when the output voltage of the power supply unit exceeds the first preset threshold, the first switch is controlled to be turned off and the second switch is controlled to be turned on to perform current detection; or when the output voltage of the power supply unit is less than the second preset threshold, the first switch is controlled to be turned on and the second switch is controlled to be turned off to store electric energy for the power supply unit, that is, the output voltage of the power supply unit falls within a range between the first preset threshold and the second preset threshold. Therefore, using the control method shown in FIG. 9 in this embodiment of this application is beneficial to ensuring that power supply to the processing unit is performed within a rated working voltage range while accuracy of a current detection result is ensured.

Based on a same technical concept, this application further provides an electric energy detection apparatus. As shown in FIG. 12, an alternating current voltage detection apparatus 1200 includes a second transformation unit 1201, a voltage detection unit 1202, and the foregoing current detection apparatus 300.

The second transformation unit 1201 is located in a hollow part of a first transformation unit in the current detection apparatus 300, and is configured to generate a third induced voltage based on an actual voltage of a detected cable. The voltage detection unit 1202 is separately connected to a power supply unit in the current detection apparatus 300 and the second transformation unit 1201, and is configured to: convert the third induced voltage into a third voltage and output the third voltage to a processing unit in the current detection apparatus 300. The current detection apparatus 300 is coupled to the detected cable, and is configured to: detect a current value on the detected cable, and calculate, based on the third voltage and the current value on the detected cable, electric energy transmitted on the detected cable.

Specifically, the second transformation unit is of a closed or non-closed magnetic core structure. FIG. 13 is a schematic diagram of a structure of a second transformation unit. The second transformation unit is connected in the hollow part of the first transformation unit in the current detection apparatus, to reduce a volume of an electric energy detection apparatus.

In a possible implementation, the second transformation unit may be a voltage transformer. The voltage transformer is configured to generate the third induced voltage based on the actual voltage on the detected cable and coupling capacitance.

In a possible implementation, a voltage sensor is of a conductive cylindrical structure, the detected cable passes through the voltage sensor, the voltage sensor and the detected cable form the coupling capacitance, and the voltage sensor is of a closed or non-closed cylindrical structure. The voltage sensor is made of a metal material. FIG. 14 is a schematic diagram of a structure of a voltage sensor. The voltage sensor is a foil made of a copper material, and the copper foil may be coiled in a closed or non-closed manner. After the copper foil is sleeved outside the detected cable, the coupling capacitance is generated between the detected cable and the copper foil C_x.

The voltage sensor may alternatively be of a cylindrical structure different from that shown in FIG. 14, or may be a polygonal cylindrical structure, such as a square cylindrical structure or a rectangular cylindrical structure. In addition, the voltage sensor may alternatively be of a non-cylindrical metal bipolar plate structure. Specifically, a metal bipolar plate may be disposed on two sides of the detected cable, so that the detected cable passes through the metal bipolar plate, thereby forming the coupling capacitance C