Power supply-bidirectional communication system and power supply-bidirectional communication method suitable for elevator energy-saving device, elevator energy-saving device and elevator

Abstract

The invention discloses a power supply-bidirectional communication system suitable for an elevator energy-saving device, a power supply-bidirectional communication method, the elevator energy-saving device and an elevator, the elevator energy-saving device comprises a converter and an energy storage device, the elevator comprises a direct current bus, the input side of the converter is connected with the energy storage device, and the output side of the converter is connected with the direct current bus; the power supply-bidirectional communication system comprises a signal generation system, and the signal generation system is used for changing a driving signal of a switching tube in the converter so as to embed the signal into current ripples at the input side and the output side of the converter; when the input side receives data, demodulating the emitted current of the sampled energy storage device to restore the transmitted signal; when the output side receives data, the sampled DC bus current is demodulated to restore the transmit signal.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of elevators and communication technology, in particular to a power-supply bidirectional communication system and method suitable for an elevator energy-saving device, an elevator energy-saving device and an elevator comprising the power-supply bidirectional communication system. BACKGROUND

[0002] With the rapid development of modern buildings towards high-rise and intelligentization, the energy consumption problem of elevator systems as the core equipment of vertical transportation has been increasingly concerned. The traditional elevator system has low energy utilization rate due to the frequent start-stop operation of elevators and the complex energy feedback demand. In recent years, elevator energy-saving technology based on energy storage devices (such as supercapacitors and lithium batteries) has gradually become a research hotspot. By recovering braking energy and dynamically adjusting power flow, energy consumption can be significantly reduced. However, the efficient cooperation between energy storage devices and elevator main control systems depends on stable energy transmission and real-time communication, which puts higher requirements on power-supply communication integrated technology.

[0003] The elevator system is a complex mechatronic system with multi-module cooperation, and its safety and energy efficiency highly depend on real-time communication between components. However, there are still some key technical problems to be solved in multi-module communication. For example, the energy storage device needs to dynamically adjust the charging and discharging strategy according to the load state of the traction machine, the main control system needs to obtain the bus voltage and current data in real time to optimize energy scheduling, and fault diagnosis and emergency response cannot be implemented without precise signal interaction.

[0004] In the traditional communication scheme, energy transmission and communication functions are usually realized by independent hardware (such as CAN bus or GPRS wireless public network), which leads to high system complexity, increased cost, and problems such as wiring difficulty and electromagnetic interference. In addition, once the external communication module fails, the state monitoring and cooperative control functions of the elevator energy-saving device system cannot be implemented.

[0005] The existing patent 2016108467764, an elevator drive control and energy-saving integrated system and method, collects and transmits data through an elevator operation information collection unit to monitor the elevator operation state, but the additional communication hardware increases the overall device cost.

[0006] For example, the patent 202410984463X, elevator control method, device, equipment and computer readable medium, although the control of the entire elevator system is based on the detection of bus current, it not only needs an additional communication interface, but also the detected current is only used to adjust the corresponding energy storage control strategy, which belongs to power electronic control and does not undertake the role of signal transmission and communication implementation.

[0007] Therefore, exploring a low-cost and high-reliability elevator energy-saving device bidirectional communication technology can not only realize high integration of power transmission and signal interaction, but also provide an emergency communication scheme under a communication module fault condition.

[0008] The disclosure of the above background art is only used to assist in understanding the inventive concept and technical solutions of the present application, and does not necessarily belong to the prior art of the present application. In the absence of explicit evidence that the above content has been disclosed before the filing date of the present application, the above background art should not be used to evaluate the novelty and inventiveness of the present application. SUMMARY

[0009] Therefore, exploring a low-cost and high-reliability elevator energy-saving device bidirectional communication technology can not only realize high integration of power transmission and signal interaction, but also provide an emergency communication scheme under a communication module fault condition.

[0010] In order to achieve the above purpose, the present application adopts the following technical solutions:

[0011] A power supply-bidirectional communication system suitable for an elevator energy-saving device, the elevator energy-saving device comprising a converter and an energy storage device, the elevator comprising a direct current bus, the input side of the converter being connected to the energy storage device, and the output side being connected to the direct current bus; the power supply-bidirectional communication system comprising a signal generation system, the signal generation system being used to change the driving signal of the switch tube in the converter, so as to embed signals in the current ripple of the input side and the output side of the converter; when the input side receives data, the emitted current of the sampled energy storage device is demodulated to restore the transmitted signal; when the output side receives data, the sampled direct current bus current is demodulated to restore the transmitted signal. The signal generation system of the present application belongs to a part of the elevator energy-saving device, and is a module embedded in the converter. The controller of the converter is originally used to control power transmission, and is now multiplexed as a signal generation system on the basis of the original task.

[0012] According to some preferred embodiments of the present application, the signal generation system comprises a signal modulation subsystem and a driving subsystem, the signal modulation subsystem being used to perform phase shift keying modulation on the signal to be transmitted; the driving subsystem controls the switch tube of the converter by sending driving pulses of different phases under equal-power symmetric phase shift control based on the phase shift keying modulated signal, so that the input side and the output side of the converter generate current ripples containing two specific phases, and are respectively reflected in the emitted current of the energy storage device and the direct current bus current.

[0013] According to some preferred embodiments of the present application, the signal modulation subsystem comprises a signal generator, an encoder, a control variable regulator and a phase switcher, the signal generator and the encoder are used to encode the data to be transmitted into binary signals, the control variable regulator and the phase switcher are used to calculate the symmetric phase shift ratio and generate the corresponding control variable according to the binary signal outputted by the encoder.

[0014] According to some preferred embodiments of the present application, the driving subsystem comprises a carrier generator, a phase shift calculator, a comparator and a NOT gate, the phase shift calculator is connected with the signal modulation subsystem and used to receive the output of the signal modulation subsystem, the comparator is used to compare the output of the phase shift calculator with the output of the carrier generator and generate the driving signal of the first switch tube, the output of the comparator is connected with the NOT gate, and the NOT gate generates the driving signal of the second switch tube.

[0015] According to some preferred embodiments of the present application, the driving signal of the first switch tube in the converter is complementary to the driving signal of the second switch tube.

[0016] According to some preferred embodiments of the present application, the first switch tube comprises switch tubes S1, S3, Q1 and Q3, and the second switch tube comprises switch tubes S2, S4, Q2 and Q4.

[0017] According to some preferred embodiments of the present application, the phase shift calculator comprises first, second, third and fourth phase shift calculators, the comparator comprises first, second, third and fourth comparators, the NOT gate comprises first, second, third and fourth NOT gates, the first, second, third and fourth comparators output the driving signals of switch tubes S1, S3, Q1 and Q3 respectively, and the first, second, third and fourth NOT gates output the driving signals of switch tubes S2, S4, Q2 and Q4 respectively.

[0018] According to some preferred embodiments of the present application, the converter is a resonant bidirectional DC / DC converter.

[0019] According to some preferred embodiments of the present invention, the demodulation involves inputting the input current or output current signal of the converter into a filter to remove DC and high-frequency signals. The filtered signal is then subjected to an FFT transformation to calculate the initial phase of the second harmonic (as shown in the formula below) and matched with the modulation algorithm to obtain the original signal emitted by the signal generation system, thereby restoring the original data. Demodulation is also implemented by multiplexing the converter's controller, which acts as both a signal transmitting (modulation) device and a signal receiving (demodulation) device.

[0020] According to some preferred embodiments of the present invention, the phase of the input current of the converter under symmetrical phase shift is calculated based on the second harmonic Fourier coefficient of the input current, specifically as follows:

[0021]

[0022] In the formula, N is the turns ratio of the primary and secondary sides of the converter transformer, and U o d1 is the DC bus voltage on the output side of the converter, d1 is the phase shift between the diagonal power transistor drive signals and the phase shift ratio within the bridge, and Z0 is the resonant impedance. L1, L2, and C are the inductance and capacitance of the LCL resonant slot of the converter, respectively, and α and β are a set of symmetrical shift ratios under the same transmission power.

[0023] According to some preferred embodiments of the present invention, the phase of the output current of the converter under symmetrical phase shift is calculated based on the second harmonic Fourier coefficient of the output current, specifically as follows:

[0024]

[0025] In the formula, N is the turns ratio of the primary and secondary sides of the converter transformer, and U o d1 is the DC bus voltage on the output side of the converter, d1 is the phase shift between the diagonal power transistor drive signals and the phase shift ratio within the bridge, and Z0 is the resonant impedance. L1, L2, and C are the inductance and capacitance of the LCL resonant slot of the converter, respectively, and α and β are a set of symmetrical shift ratios under the same transmission power.

[0026] The application also provides a power-supply-bidirectional communication method suitable for an elevator energy-saving device based on the power-supply-bidirectional communication system, comprising the following steps: a signal generation system is used to generate a signal to be transmitted, a driving subsystem generates driving pulses of different phases under the control of equal-power symmetric phase shift, controls power switches of a resonant bidirectional DC / DC converter, and makes the input and output sides generate current ripples containing two specific phases without affecting power supply, so that the current generated by the energy storage device and the DC bus current are embodied, respectively, signal demodulation is achieved by extracting ripple signals on the current generated by the energy storage device and the DC bus current, restoring the original signal according to the analyzed phase change, and realizing bidirectional transmission of signals.

[0027] According to some preferred embodiments of the application, the power-supply-bidirectional communication method comprises the following steps:

[0028] Step 1 (bus voltage adjustment): according to the collected electrical quantities such as voltage and current, the power control loop in the control quantity regulator calculates a phase shift control quantity d, adjusts the size and direction of power transmission of the bidirectional DC / DC converter, and maintains the stability of the bus voltage;

[0029] Step 2 (signal modulation): encode the data to be transmitted into a binary signal, the control quantity regulator and the phase switcher calculate a set of equal-power symmetric phase shift ratios alpha and beta according to the binary signal, use the phase shift keying mode, map the encoded binary signal into different phase shift ratio variables, and correspond to different second harmonic initial phases;

[0030] Step 3 (driving implementation): the driving subsystem generates driving pulses of full-bridge power tubes according to the modulated phase shift ratio variables, embeds specific phase ripples in the input and output side currents of the converter without affecting power transmission;

[0031] Step 4 (signal extraction): filter the collected input side current or output side current signal to remove DC and high-frequency component interference, and retain the second harmonic component containing data information;

[0032] Step 5 (signal demodulation): perform FFT transformation on the filtered current signal, extract the initial phase of the second harmonic, compare the detected phase with the mapping relationship during modulation, restore the original binary signal, and thus restore the original data.

[0033] The application also provides an elevator energy-saving device comprising the power-supply-bidirectional communication system.

[0034] The application also provides an elevator comprising the power-supply-bidirectional communication system.

[0035] According to some preferred embodiments of the present application, the elevator further comprises a single-phase uncontrolled AC / DC rectifier, a DC bus, a control center, a speed regulator, a motor and an elevator energy-saving device, the elevator energy-saving device comprising a converter and an energy storage device, the input side of the converter being connected to the energy storage device and the output side being connected to the DC bus; the control center being connected to the DC bus, the single-phase uncontrolled AC / DC rectifier being connected between the power grid and the DC bus, and the speed regulator being connected between the motor and the DC bus.

[0036] Compared with the prior art, the power-supply-bidirectional communication system for the elevator energy-saving device of the present application modulates the data to the power switch inside the converter to generate current ripple signals carrying data information at the input and output sides, without the need for an independent communication channel, and realizes bidirectional transmission of signals of the elevator energy-saving device while transmitting power, thereby reducing the hardware cost of the system; the driving signal of the power switch of the converter is changed by the symmetrical phase shift combined with the phase shift keying modulation method, which is simple and does not harm the power supply quality during bidirectional communication. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort.

[0038] Figure 1 The structure schematic diagram of the elevator in the preferred embodiments of the present application is shown in the figure.

[0039] Figure 2 The processing flow schematic diagram of the power-supply-bidirectional communication method in the preferred embodiments of the present application is shown in the figure.

[0040] Figure 3 The typical operation waveform diagram of the resonant bidirectional DC / DC converter under the double phase shift control in the preferred embodiments of the present application is shown in the figure.

[0041] Figure 4 The structure schematic diagram of the signal generation system in the preferred embodiments of the present application is shown in the figure.

[0042] Figure 5 The waveform diagram of data transmission and reception in the preferred embodiments of the present application is shown in the figure.

[0043] Figure 6 The waveform diagram of data transmission and reception under input voltage disturbance in the preferred embodiments of the present application is shown in the figure.

[0044] Figure 7 The waveform diagram of data transmission and reception under output voltage disturbance in the preferred embodiments of the present application is shown in the figure. Detailed Implementation

[0045] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0046] The present invention relates to an elevator energy-saving device power supply-bidirectional communication system and communication method, which aims to solve the shortcomings of existing elevator energy-saving device systems, such as high communication cost, high complexity, and weak emergency communication capability.

[0047] Specifically, such as Figure 1 As shown, the elevator of this invention includes a single-phase uncontrolled AC / DC rectifier, a DC bus, a control center, a speed controller, a motor, and an elevator energy-saving device. The elevator energy-saving device includes a bidirectional DC / DC converter and an energy storage device. The control center is connected to the DC bus, the single-phase uncontrolled AC / DC rectifier is connected between the power grid and the DC bus, and the speed controller is connected between the motor and the DC bus. The bidirectional DC / DC converter is connected to the DC bus and the energy storage device on both sides, respectively. It can adjust the power flow direction and communication direction according to the power supply balance condition of the DC bus to achieve energy saving. Specifically, the converter adopts a phase-shift control method, which adjusts the direction and magnitude of the transmitted power by controlling the phase shift time between the drive signals of each power transistor.

[0048] Specifically, such as Figure 2 As shown, the input side of the bidirectional DC / DC converter is connected to an energy storage device, and the output side is connected to a DC bus. The power supply-bidirectional communication system includes a signal generation system, which is used to change the drive signals of the switching transistors in the converter. When transmitting data, the signal generation system changes the drive signals of the converter's switching transistors, thereby embedding the signal into the current ripples on the input and output sides of the converter. When receiving data on the input side, the sampled current from the energy storage device is demodulated to reconstruct the transmitted signal. When receiving data on the output side, the sampled DC bus current is demodulated to reconstruct the transmitted signal. The signal generation system is part of the elevator energy-saving device and is a module embedded in the converter. The converter's controller, originally used to control power transmission, is now reused as a signal generation system based on its original function.

[0049] The elevator energy-saving device includes a converter and an energy storage device. The converter is a resonant bidirectional DC / DC converter. The converter's switching transistors include first switching transistors S1, S3, Q1, and Q3, and second switching transistors S2, S4, Q2, and Q4. The drive signals of the first switching transistors and the second switching transistors are complementary.

[0050] Demodulation involves inputting the input current or output current signal of the converter into a filter to remove DC and high-frequency signals. The filtered signal is then subjected to FFT transformation, and the initial phase of the second harmonic is calculated and matched with the modulation algorithm to obtain the original signal generated by the signal generation system, thereby restoring the original data.

[0051] The phase of the input current of the symmetrical phase-shifted downconverter is calculated based on the second harmonic Fourier coefficient of the input current, as shown in the following formula:

[0052]

[0053] In the formula, N is the turns ratio of the primary and secondary sides of the converter transformer, and U o d1 is the DC bus voltage on the output side of the converter, d1 is the phase shift between the diagonal power transistor drive signals and the phase shift ratio within the bridge, and Z0 is the resonant impedance. L1, L2, and C are the inductance and capacitance of the LCL resonant slot of the converter, respectively, and α and β are a set of symmetrical shift ratios under the same transmission power.

[0054] The phase of the output current of the symmetrical phase-shifted downconverter is calculated based on the second harmonic Fourier coefficient of the output current, as shown in the following formula:

[0055]

[0056] In the formula, N is the turns ratio of the primary and secondary sides of the converter transformer, and U o d1 is the DC bus voltage on the output side of the converter, d1 is the phase shift between the diagonal power transistor drive signals and the phase shift ratio within the bridge, and Z0 is the resonant impedance. L1, L2, and C are the inductance and capacitance of the LCL resonant slot of the converter, respectively, and α and β are a set of symmetrical shift ratios under the same transmission power.

[0057] like Figure 4 As shown, the signal generation system includes a signal modulation subsystem and a drive subsystem. The signal modulation subsystem is used to perform phase shift keying modulation on the signal to be transmitted. The drive subsystem, based on the phase shift keying modulated signal, controls the switching transistors of the converter by sending drive pulses of different phases under equal power symmetrical phase shift control, so that the input and output sides of the converter generate current ripples containing two specific phases, which are reflected in the current emitted by the energy storage device and the DC bus current, respectively.

[0058] Specifically, the signal modulation subsystem includes a signal generator, an encoder, a control variable regulator, and a phase switcher. The signal generator and encoder encode the data to be transmitted into binary signals. The control variable regulator and phase switcher calculate the symmetrical shift ratio and generate corresponding control variables based on the binary signal output by the encoder, and then output these variables. The control variable regulator calculates the shift ratio d, and based on d, obtains the symmetrical shift ratios α and β. According to the transmitted signal, it switches the final shift ratio between α and β to transmit the signal.

[0059] The driving subsystem includes a carrier generator, a phase shifter, a comparator, and a NOT gate. The phase shifter is connected to the signal modulation subsystem and is used to receive the output of the signal modulation subsystem. The comparator is used to compare the output of the phase shifter with the output of the carrier generator and generate a driving signal for the first switching transistor. The output of the comparator is connected to the NOT gate, and the NOT gate generates a driving signal for the second switching transistor.

[0060] Corresponding to the switching transistors of the converter, the phase shifters include a first phase shifter, a second phase shifter, a third phase shifter, and a fourth phase shifter; the comparators include a first comparator, a second comparator, a third comparator, and a fourth comparator; the NOT gates include a first NOT gate, a second NOT gate, a third NOT gate, and a fourth NOT gate; the first, second, third, and fourth comparators output drive signals for switching transistors S1, S3, Q1, and Q3 respectively, and the first, second, third, and fourth NOT gates output drive signals for switching transistors S2, S4, Q2, and Q4 respectively. That is, the inputs of the four phase shifters are connected to the output of the signal modulation subsystem, and the outputs of the phase shifters are compared with the output of the triangular carrier generator to generate drive signals for switching transistors S1, S3, Q1, and Q3. The outputs of the comparators are connected to the NOT gates to generate drive signals for switching transistors S2, S4, Q2, and Q4.

[0061] This invention also provides a power supply-bidirectional communication method for elevator energy-saving devices based on the above power supply-bidirectional communication system: The signal generation system generates the signal to be transmitted. Combined with phase shift keying modulation, the drive subsystem controls the power switch of the resonant bidirectional DC / DC converter by sending drive pulses of different phases under equal power symmetrical phase shift control. Without affecting the power supply, the input and output sides generate current ripples containing two specific phases, which are reflected in the current emitted by the energy storage device and the DC bus current, respectively. The signal demodulation extracts the ripple signals on the current emitted by the energy storage device and the DC bus current, and restores the original signal according to the analyzed phase changes, thereby realizing bidirectional signal transmission.

[0062] Specifically, the power supply-bidirectional communication method includes the following steps:

[0063] Step 1: Bus voltage adjustment

[0064] Based on the collected electrical quantities such as voltage and current, the power control loop in the control quantity regulator calculates the phase shift control quantity d, adjusts the magnitude and direction of power transmission of the bidirectional DC / DC converter, and maintains the stability of the bus voltage.

[0065] Step 2, Signal Modulation

[0066] The data to be transmitted (such as instructions issued by the control center to the energy storage device or status information fed back from the energy storage device to the control center) is encoded into binary signals. The control quantity regulator and the phase switcher calculate a set of equal power symmetrical shift ratios α and β based on the binary signals. Using phase shift keying, the encoded binary signals are mapped to different shift ratio variables, corresponding to different second harmonic initial phases.

[0067] Step 3: Driver Implementation

[0068] The drive subsystem generates drive pulses for the full-bridge power transistors based on the modulated phase shift variable, embedding specific phase ripples into the input and output currents of the converter without affecting power transmission.

[0069] Step 4: Signal Extraction

[0070] The controller filters out DC and high-frequency interference from the acquired input or output current signals, while retaining the second harmonic component containing the data information.

[0071] Step 5: Signal Demodulation

[0072] The filtered current signal is subjected to FFT transformation to extract the initial phase of the second harmonic, and the detected phase is compared with the mapping relationship during modulation to restore the original binary signal, thereby restoring the original data.

[0073] The signal is transmitted embedded in the electrical energy ripple, so the electrical energy transmission characteristics also represent the signal transmission characteristics; the symmetrical phase-shift modulation method of this invention depends on the specific characteristics of the energy transmission method. Based on the above communication system structure and method, the energy transmission method of the elevator energy-saving device power supply-bidirectional communication system of this invention is as follows:

[0074] The resonant bidirectional DC / DC converter first inverts the input DC power into a high-frequency AC square wave voltage through a full-bridge circuit on the primary side. This high-frequency AC voltage then passes through an LCL resonant tank and a high-frequency isolation transformer, and is rectified to output DC power through a full-bridge circuit on the secondary side. This topology can be equivalent to having high-frequency AC square wave voltage sources connected to both sides of the resonant tank. The converter employs phase-shift control, adjusting the direction and magnitude of the transmitted power by controlling the phase shift time between the drive signals of each power transistor.

[0075] Taking dual-phase-shift control as an example, each power switch drive signal is a square wave with a frequency of fs, a period of Ts, and a duty cycle of 50%. The drive signals of the two power transistors on the same bridge arm are complementary, i.e., S1 and S2, S3 and S4, Q1 and Q2, and Q3 and Q4 are complementary. The phase shift between the diagonal power transistor drive signals is the intra-bridge phase shift, i.e., the phase shift time between the S1 and S4, and Q1 and Q4 drive signals is d1Ts. The phase shift time between the voltages of the two full-bridge sides is the inter-bridge phase shift, which is dTs. Figure 3 As shown, the switching functions of the two full-bridge power switches are defined as gP(t) and gS(t), respectively. Then, the switching functions under dual-phase-shift control can be expressed as follows:

[0076]

[0077] In the formula, d1 is the phase shift ratio between the diagonal power transistor drive signals and the bridge internal phase shift ratio, d is the phase shift ratio between the primary and secondary full-bridge drive signals, and T is the phase shift ratio between the primary and secondary sides. s This represents the switching cycle of the drive signal.

[0078] Define the resonant frequency as The resonant impedance is When the converter switching frequency coincides with the resonant frequency, the voltage-current relationship across the resonant slot, derived using the fundamental approximation method, can be expressed as:

[0079]

[0080] In the formula, N is the turns ratio of the high-frequency transformer, Uin is the input voltage, and Uo is the output voltage. Therefore, the average power transfer of the resonant bidirectional DC / DC converter is:

[0081]

[0082] It can be concluded that when the inner shift ratio d1 is constant, the transmission power first increases and then decreases symmetrically with the increase of the outer shift ratio d, reaching its maximum value when d = 0.25. Two shift ratios with the same transmission power are defined as a set of symmetrical shift ratios, denoted as α and β. Then α = d = 0.5 - β, where the range of d is limited to 0 ≤ d ≤ 0.25. Therefore, α varies from 0 to 0.25, while β varies from 0.25 to 0.5.

[0083] The power supply-bidirectional communication method of the elevator energy-saving device of the present invention is as follows: by switching equal power symmetrical phase shift and combining it with phase shift keying modulation method, different phase ripples carrying data are embedded into the input and output currents of the converter, and bidirectional signal transmission is achieved by modulating and demodulating the bus current.

[0084] like Figure 4As shown, the signal generation system includes a signal modulation subsystem and a drive subsystem, with the specific structure as described above. The signal generation system generates the signal to be transmitted. Combined with phase shift keying modulation, the drive subsystem controls the power switch of the resonant bidirectional DC / DC converter by sending drive pulses of different phases under equal power symmetrical phase shift control. This generates current ripples containing two specific phases on the input and output sides without affecting the power supply, which are then reflected in the current emitted by the energy storage device and the DC bus current, respectively.

[0085] The signal b(t) sent by the converter during symmetrical phase-shift control can be expressed as:

[0086]

[0087] Based on the above formula and the switching ratio of the transmitted signal, the key to achieving bidirectional data communication is the modulation of the input and output currents of the converter and information extraction. To ensure the quality of power transmission and the stability of the communication signal, the focus of modulation is to determine the amplitude, frequency, and phase of the current ripple. The theoretical calculation of the correspondence between the current ripple and the modulation parameters of the resonant bidirectional DC / DC converter in this invention is as follows:

[0088] Due to the rectification effect of the full-bridge converter on both sides, the input and output currents only contain even-order harmonic components. Under different inter-bridge phase-shift control, the second harmonic components of the input and output currents will have different initial phases, thus transmitting the corresponding signals. The phases of the input and output currents of the converter under symmetrical phase shift can be obtained from their Fourier series coefficients, as follows:

[0089]

[0090]

[0091] In the formula, N is the turns ratio of the primary and secondary sides of the converter transformer, and U o d1 is the DC bus voltage on the output side of the converter, d1 is the phase shift between the diagonal power transistor drive signals and the phase shift ratio within the bridge, and Z0 is the resonant impedance. L1, L2, and C are the inductance and capacitance of the LCL resonant slot of the converter, respectively, and α and β are a set of symmetrical shift ratios under the same transmission power.

[0092] Signal demodulation extracts the ripple signals from the current emitted by the energy storage device and the DC bus current, and restores the original signal based on the analyzed phase changes, thus achieving bidirectional signal transmission. The ripple analysis described above, which studies the relationship between the ripple signal and system parameters, can provide a reference for the design of the demodulation stage in communication systems.

[0093] Examples of the signal demodulation method of the present invention are as follows:

[0094] First, the collected output current signals of the energy storage device (corresponding to the input current of the converter) and the bus current signals (corresponding to the output current of the converter) are input into a bandpass filter to filter out DC and high-frequency signals. The filtered signals are then subjected to FFT transformation, and the initial phase of the second harmonic is calculated and matched with the modulation algorithm to obtain the original signal emitted by the signal generation system, thereby restoring the original data. This algorithm can be implemented using digital processors such as DSPs.

[0095] Figure 5 The diagram shows the data transmission and reception waveforms obtained in the Matlab / Simulink simulation of this embodiment, demonstrating that the input signal can be successfully received and demodulated, and the original information can be read out. After modulation of the symmetrical shift ratio according to a specific switching rule, the signal can be embedded in the second harmonic components of the converter's input and output current ripples and transmitted along with the electrical energy. The signal transmission rate is 0.5 kbps, and the transmitted signal can be successfully demodulated at the receiving end. The data demodulation delay measured at the signal receiving end is 2 ms. This delay is related to the impedance of the power transmission line, the controller delay, and the demodulation calculation process.

[0096] Figure 6 and Figure 7 The figures show the data transmission and reception waveforms under input and output voltage disturbances obtained in the Matlab / Simulink simulation of this embodiment. The results show that even during transient processes under disturbances, the power supply-bidirectional communication method of the elevator energy-saving device of this invention can still inject the transmitted signal into the ripple on the input and output sides of the converter. The data receiving end can still correctly demodulate the signal transmitted from the converter end by analyzing the harmonic characteristics of the current ripple and extracting harmonics of specific phases.

[0097] The elevator energy-saving device power supply-bidirectional communication system and communication method of the present invention are based on a resonant bidirectional DC / DC converter. The two sides of the converter are connected to the elevator system's DC bus and an energy storage device, respectively. When transmitting data, the drive signal of the converter's switching transistor is changed through a signal generation system, thereby embedding the signal into the current ripple on the input and output sides of the converter. When receiving data on the input side, the sampled current from the energy storage device is demodulated to reconstruct the transmitted signal. When receiving data on the output side, the sampled DC bus current is demodulated to reconstruct the transmitted signal. Power flow can be adjusted according to the DC bus power supply balance condition to achieve energy saving. Taking dual-phase-shift control as an example, to achieve power supply-bidirectional communication for the elevator energy-saving device, the present invention adopts a novel communication method. By switching equal-power symmetrical phase shifts and combining them with phase-shift keying modulation, different phase ripples carrying data are embedded into the input and output currents of the converter. Bidirectional signal transmission is achieved through modulation and demodulation of the bus current. This invention does not require additional hardware circuits or communication devices. While the energy-saving device is supplying power normally, it can accurately achieve synchronous transmission of power and signal based solely on the current ripple on the input and output sides. Furthermore, the transmission directions of power and signal are decoupled, resulting in low cost and high accuracy. This invention provides a new technical approach for power supply and bidirectional communication in elevator energy-saving devices.

[0098] Compared to patent 201610846776.4, this invention directly utilizes existing power electronic controllers as signal modulation and demodulation devices for signal communication, significantly reducing costs. Compared to patent 202410984463.X, this invention embeds the signal into the bus current through a specific modulation method, enabling communication signals and electrical energy to be transmitted synchronously on the power line, resulting in higher integration.

[0099] Compared with the prior art, the beneficial technical effects of this invention are as follows: On the one hand, this invention uses the internal power switch of the bidirectional DC / DC converter as the data modulation execution mechanism to generate current ripple signals carrying data information on the input and output sides. It does not require an independent communication channel and realizes bidirectional transmission of elevator energy-saving device signals while transmitting power, thus reducing system hardware costs. On the other hand, this invention makes full use of the operating characteristics of the internal resonant bidirectional DC / DC converter of the elevator energy-saving device. It changes the drive signal of the converter power switch by combining symmetrical shift and phase shift keying modulation. The method is simple and does not impair power supply quality during bidirectional communication.

[0100] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A power supply-bidirectional communication system suitable for elevator energy-saving devices, characterized in that: The elevator energy-saving device includes a converter and an energy storage device. The elevator includes a DC bus. The input side of the converter is connected to the energy storage device, and the output side is connected to the DC bus. The power supply-bidirectional communication system includes a signal generation system. The signal generation system is used to change the drive signal of the switching transistor in the converter, thereby embedding the signal into the current ripple on the input and output sides of the converter. When the input side receives data, the sampled current emitted by the energy storage device is demodulated to restore the transmitted signal. When the output side receives data, the sampled DC bus current is demodulated to restore the transmitted signal.

2. The power supply-bidirectional communication system according to claim 1, characterized in that, The signal generation system includes a signal modulation subsystem and a driving subsystem. The signal modulation subsystem is used to perform phase shift keying modulation on the signal to be transmitted. The driving subsystem, based on the phase shift keying modulated signal, controls the switching transistors of the converter by sending driving pulses of different phases under equal power symmetrical phase shift control, so that the input and output sides of the converter generate current ripples containing two specific phases, which are reflected in the output current of the energy storage device and the DC bus current, respectively.

3. The power supply-bidirectional communication system according to claim 2, characterized in that, The signal modulation subsystem includes a signal generator, an encoder, a control quantity regulator, and a phase switcher. The signal generator and encoder are used to encode the data to be transmitted into binary signals. The control quantity regulator and phase switcher are used to calculate the symmetric shift ratio, generate corresponding control variables based on the binary signals output by the encoder, and output them.

4. The power supply-bidirectional communication system according to claim 2, characterized in that, The driving subsystem includes a carrier generator, a phase shift calculator, a comparator, and a NOT gate. The phase shift calculator is connected to the signal modulation subsystem and is used to receive the output of the signal modulation subsystem. The comparator is used to compare the output of the phase shift calculator with the output of the carrier generator and generate a driving signal for the first switching transistor. The output of the comparator is connected to the NOT gate, and the NOT gate generates a driving signal for the second switching transistor.

5. The power supply-bidirectional communication system according to claim 4, characterized in that, The drive signal of the first switch in the converter is complementary to the drive signal of the second switch.

6. The power supply-bidirectional communication system according to claim 4, characterized in that, The first switching transistor includes switching transistors S1, S3, Q1, and Q3; the second switching transistor includes switching transistors S2, S4, Q2, and Q4.

7. The power supply-bidirectional communication system according to claim 6, characterized in that, The phase shift calculator includes a first phase shift calculator, a second phase shift calculator, a third phase shift calculator, and a fourth phase shift calculator; the comparator includes a first comparator, a second comparator, a third comparator, and a fourth comparator; the NOT gate includes a first NOT gate, a second NOT gate, a third NOT gate, and a fourth NOT gate; the first comparator, the second comparator, the third comparator, and the fourth comparator respectively output drive signals for switching transistors S1, S3, Q1, and Q3, and the first NOT gate, the second NOT gate, the third NOT gate, and the fourth NOT gate respectively output drive signals for switching transistors S2, S4, Q2, and Q4.

8. The power supply-bidirectional communication system according to claim 1, characterized in that, The converter is a resonant bidirectional DC / DC converter.

9. The power supply-bidirectional communication system according to claim 1, characterized in that, The demodulation process involves inputting the input current or output current signal of the converter into a filter to remove DC and high-frequency signals. The filtered signal is then subjected to FFT transformation, and the initial phase of the second harmonic is calculated and matched with the modulation algorithm to obtain the original signal generated by the signal generation system, thereby restoring the original data.

10. The power supply-bidirectional communication system according to claim 1, characterized in that, The phase of the input current of the converter under symmetrical phase shift is calculated based on the second harmonic Fourier coefficient of the input current, specifically as follows: ； In the formula, N is the turns ratio of the primary and secondary sides of the converter transformer, and U o d1 is the DC bus voltage on the output side of the converter, d1 is the phase shift between the diagonal power transistor drive signals and the phase shift ratio within the bridge, and Z0 is the resonant impedance. L1, L2, and C are the inductance and capacitance of the LCL resonant slot of the converter, respectively, and α and β are a set of symmetrical shift ratios under the same transmission power.

11. The power supply-bidirectional communication system according to claim 1, characterized in that, The phase of the output current of the converter under symmetrical phase shift is calculated based on the second harmonic Fourier coefficient of the output current, specifically as follows: ； In the formula, N is the turns ratio of the primary and secondary sides of the converter transformer, and U o d1 is the DC bus voltage on the output side of the converter, d1 is the phase shift between the diagonal power transistor drive signals and the phase shift ratio within the bridge, and Z0 is the resonant impedance. L1, L2, and C are the inductance and capacitance of the LCL resonant slot of the converter, respectively, and α and β are a set of symmetrical shift ratios under the same transmission power.

12. A power supply-bidirectional communication method for elevator energy-saving devices based on the power supply-bidirectional communication system as described in any one of claims 1-11.

13. The power supply-bidirectional communication method according to claim 12, characterized in that, Includes the following steps: Based on the collected electrical signals, the power control loop in the control quantity regulator calculates the phase shift control quantity d, adjusts the magnitude and direction of the converter's cycle power transmission, and maintains the stability of the bus voltage. The data to be transmitted is encoded into a binary signal. The control quantity regulator and the phase switcher calculate a set of equal power symmetrical shift ratios α and β based on the binary signal. Using phase shift keying, the encoded binary signal is mapped to different shift ratio variables, corresponding to different second harmonic initial phases. The drive subsystem generates drive pulses for the full-bridge power transistors based on the modulated phase shift variable, so that specific phase ripples are embedded in the input and output currents of the converter. The collected input or output current signals are filtered to remove DC and high-frequency interference components, while retaining the second harmonic component containing data information. The filtered current signal is subjected to FFT transformation to extract the initial phase of the second harmonic, and the detected phase is compared with the mapping relationship during modulation to restore the original binary signal, thereby restoring the original data.

14. An elevator energy-saving device comprising a power supply-bidirectional communication system as described in any one of claims 1-11.

15. An elevator comprising a power supply-bidirectional communication system as described in any one of claims 1-11.

16. The elevator according to claim 15, characterized in that, The system includes a single-phase uncontrolled AC / DC rectifier, a DC bus, a control center, a speed controller, a motor, and an elevator energy-saving device. The elevator energy-saving device includes a converter and an energy storage device. The input side of the converter is connected to the energy storage device, and the output side is connected to the DC bus. The control center is connected to the DC bus. The single-phase uncontrolled AC / DC rectifier is connected between the power grid and the DC bus, and the speed controller is connected between the motor and the DC bus.

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