Energy recovery drive circuit and control method for adapting a ceramic electrocaloric unit

Abstract

This application relates to an energy recovery drive circuit and control method adapted to a ceramic card unit. The circuit includes: a high-voltage bus module, a main drive bridge, a resonant charging / discharging branch, an energy recovery branch, a detection module, and a digital control module. The resonant charging / discharging branch is equipped with a resonant inductor, forming a resonant circuit with the ceramic card unit. The digital control module has a built-in sequential state machine that outputs gate signals according to the pre-charging, resonant field rise, field protection, controlled recovery discharge, and heat exchange waiting stages. After the heat exchange waiting stage, it returns to the resonant field rise stage. The control method includes: after charging the energy storage element, controlling the high-voltage bus module and the energy storage element to resonantly charge the ceramic card unit through the resonant inductor, then discharging to the energy storage element through the resonant inductor, turning off all main power switches to complete heat exchange, and repeating the process cyclically. This application can suppress surge current, recover and reuse discharge energy, and improve energy utilization efficiency.

Description

Technical Field

[0001] This application relates to the field of electric card refrigeration technology, and in particular to an energy recovery drive circuit and control method adapted to ceramic electric card units, which is especially suitable for the power drive and energy management of ceramic electric card refrigeration devices. Background Technology

[0002] Electrocard cooling technology utilizes the reversible entropy and temperature changes that occur in ferroelectric / dielectric materials under varying applied electric fields to achieve a solid-state heat pump effect. It features refrigerant-free operation, easy miniaturization, potential high power density, and good compatibility with electronic packaging systems. The ceramic electrocard unit, as the core component of the electrocard cooling device, is essentially a high-voltage capacitive load. Its performance is highly dependent on parameters such as the waveform of the applied electric field, rise / fall time, hold time, and cycle frequency.

[0003] Currently, ceramic cascade capacitor cells are mostly driven using a simple high-voltage pulse direct charge-discharge method. However, since ceramic cascade capacitor cells are capacitive loads, they generate large peak currents during charging and discharging, leading to high switching losses and increased Joule heating within the ceramic material. Simultaneously, the electric field energy stored in the capacitor cell during the discharge phase is typically consumed directly through the bleed resistor or switching devices, resulting in significant energy waste on the bus. Furthermore, the simple hard-switching drive method makes it difficult to precisely control the charging slope, discharge rate, and polarization hold time of the capacitor cell. Reverse residual voltage may also increase the risk of material depolarization, affecting the stability of the cooling cycle and the long-term reliability of the device. Summary of the Invention

[0004] Based on this, it is necessary to provide an energy recovery drive circuit and control method adapted to the ceramic card unit, which can realize the recovery and reuse of discharge energy, suppress charging and discharging surge current, and adapt to the cooling cycle timing of the ceramic card, in order to address the above-mentioned technical problems.

[0005] In a first aspect, this application provides an energy recovery drive circuit adapted to a ceramic card unit, comprising: High-voltage busbar module, used to establish a DC high-voltage busbar; The main drive bridge is connected between the high-voltage bus module and the ceramic card unit, and is used to control the potential at both ends of the ceramic card unit; A resonant charging and discharging branch is connected in series or in parallel between the main drive bridge and the ceramic card unit. The resonant charging and discharging branch includes a resonant inductor, which is used to form a resonant circuit with the equivalent capacitance of the ceramic card unit. An energy recovery branch is connected between the ceramic card unit and the energy storage element, and is used to transfer the electric field energy stored in the ceramic card unit to the energy storage element during the discharge phase; The detection module is used to collect the terminal voltage of the ceramic card unit, the current of the resonant inductor, the voltage of the high-voltage bus, and the temperature signal. A digital control module is connected to the high-voltage bus module, the main drive bridge, the resonant charging and discharging branch, the energy recovery branch, and the detection module. The digital control module has a built-in timing state machine. This timing state machine outputs gate signals according to the sequential execution of a pre-charge stage, a resonant rise stage, a field-maintaining stage, a controlled recovery discharge stage, and a heat exchange waiting stage. After the heat exchange waiting stage, it returns to the resonant rise stage. The resonant rise stage includes controlling the high-voltage bus module and the energy storage element to resonate and charge the ceramic charging unit via the resonant inductor. The controlled recovery discharge stage includes controlling the ceramic charging unit to discharge to the energy storage element via the resonant inductor.

[0006] In one embodiment, the energy recovery branch includes a bidirectional switch, and the energy storage element is a recovery capacitor or the bus capacitor of the high-voltage bus module; the energy recovery branch transfers the electric field energy stored in the ceramic card unit to the recovery capacitor or back to the bus capacitor of the high-voltage bus module through the bidirectional switch.

[0007] In one embodiment, the signals collected by the detection module include the terminal voltage of the ceramic card unit, the current of the resonant inductor, the voltage of the high-voltage bus, the voltage of the energy storage element, the hot end temperature, and the cold end temperature. The detection module inputs all the collected signals into the digital control module, and the digital control module determines the resonance endpoint and the recovery cutoff point based on the signals, as well as whether the overvoltage protection threshold, overcurrent protection threshold, and overtemperature protection threshold have been reached.

[0008] In one embodiment, during the resonant rise stage, the digital control module controls the first set of switches of the main drive bridge to turn on and connects the resonant inductor to the ceramic card unit circuit; the digital control module cuts off the resonant rise stage according to the zero-crossing point of the current of the resonant inductor, or cuts off the resonant rise stage according to the terminal voltage of the ceramic card unit reaching the target voltage.

[0009] In one embodiment, during the controlled recycling discharge phase, the digital control module disconnects the main charging path and controls the energy recovery branch to be turned on; the digital control module terminates the controlled recycling discharge phase based on the zero-crossing point of the current of the resonant inductor, or based on the voltage of the energy storage element reaching the upper limit value, or based on the residual voltage of the ceramic card unit reaching a preset residual target voltage.

[0010] In one embodiment, when the voltage of the energy storage element is higher than a set value, the digital control module controls the energy storage element to be superimposed with the high-voltage bus module during the resonant rising field stage, forming an equivalent loading voltage higher than that output by the high-voltage bus module alone, which is applied to the ceramic card unit.

[0011] In one embodiment, there are multiple ceramic card units, and the multiple ceramic card units form an array and share the same high-voltage bus; each ceramic card unit is configured with a local power switch, a local sampling channel and a logic address; the digital control module performs interleaved driving on each ceramic card unit, so that adjacent ceramic card units charge and discharge at off-peak times, and preferentially allocates the energy recovered by the previous ceramic card unit to the energy storage element to the next ceramic card unit to be driven.

[0012] Secondly, this application also provides an energy recovery drive control method adapted to a ceramic card unit, comprising the following steps: Step S1: Charge the energy storage element until the voltage of the energy storage element reaches a preset threshold. Step S2: Control the high-voltage bus module and the energy storage element to resonate and charge the ceramic card unit through the resonant inductor; Step S3: Maintain the ceramic card unit at the target voltage for a preset holding time; Step S4: Control the ceramic card unit to discharge to the energy storage element through the resonant inductor; Step S5: Turn off all main power switches to allow the ceramic card unit to complete heat exchange; Steps S2 to S5 are executed sequentially in a loop, and after step S5 is completed, the process returns to step S2.

[0013] In one embodiment, in step S2, resonant charging is stopped when the current of the resonant inductor crosses zero, or when the terminal voltage of the ceramic card unit reaches the target voltage.

[0014] In one embodiment, in step S4, the discharge is terminated when the current of the resonant inductor crosses zero, or when the voltage of the energy storage element reaches an upper limit, or when the residual voltage of the ceramic card unit reaches a preset residual target voltage.

[0015] The aforementioned energy recovery drive circuit and control method adapted to the ceramic card unit form a resonant circuit with the equivalent capacitance of the ceramic card unit through the resonant inductor in the resonant charging and discharging branch. During the resonant field rise stage, the high-voltage bus module and energy storage element are controlled to resonantly charge the ceramic card unit through the resonant inductor, causing the card unit voltage to rise at a controlled slope, effectively suppressing surge current, reducing switching losses and additional Joule heat inside the ceramic material. During the controlled recovery discharge stage, the energy stored in the electric field of the ceramic card unit is transferred to the energy storage element through the resonant inductor via the energy recovery branch, avoiding direct consumption of electric field energy through the discharge resistor or switching device. The timing state machine built into the digital control module outputs gate signals sequentially according to the pre-charging stage, resonant field rise stage, field protection stage, controlled recovery discharge stage, and heat exchange waiting stage, and returns to the resonant field rise stage after the heat exchange waiting stage ends. This ensures that the electric field loading, polarization maintenance, energy recovery, and heat exchange processes of the card unit form a complete closed-loop coordination in terms of timing, guaranteeing the integrity and stability of the card cooling cycle. Furthermore, by sequentially executing steps S2 to S5, and returning to step S2 after the heat exchange waiting in step S5, the resonant field raising, field holding, recovery discharge, and heat exchange waiting constitute an uninterrupted periodic cooling cycle. Step S1 serves as an initialization step to establish an initial voltage for the energy storage element, enabling the system to directly enter the resonant field raising step after startup, without having to repeat the pre-charge operation in each cycle. This shortens the duration of the ineffective cooling phase in each cycle and improves the cooling cycle efficiency per unit time. Attached Figure Description

[0016] Figure 1 This is a structural block diagram of an energy recovery drive circuit adapted to a ceramic card unit in one embodiment; Figure 2 This is a flowchart illustrating an energy recovery drive control method adapted to a ceramic card unit in one embodiment. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. First, to facilitate understanding of the technical solutions provided by the embodiments of this application, the background technology involved in the embodiments of this application will be described below.

[0018] Electrocaloric refrigeration technology utilizes the reversible entropy and temperature changes that occur in ferroelectric / dielectric materials when an external electric field changes to achieve a solid-state heat pump effect. Its basic principle is as follows: when an electric field is applied to the electrocaloric material, the dipoles inside the material align along the direction of the electric field, the system entropy decreases, and the material temperature increases (adiabatic heating); after the electric field is removed, the dipoles tend to become disordered, the system entropy increases, and the material temperature decreases (adiabatic cooling). Through this reversible process, the electrocaloric material can transport heat from the cold end to the hot end, achieving a cooling effect.

[0019] Compared to traditional vapor compression refrigeration, electrocardiogram (ECG) refrigeration offers significant advantages, including refrigerant-free operation, ease of miniaturization, potential high power density, and good compatibility with electronic packaging systems. These characteristics make ECG refrigeration technology particularly suitable for integrated circuit thermal management scenarios such as high heat flux density chip heat dissipation, local hotspot suppression, and pixel-level temperature control. In terms of materials, ceramic ECG materials offer advantages over traditional thermoelectric refrigeration materials, including faster response speed, wider temperature range, and on-chip integration capabilities, thus becoming an important research direction for chip-level thermal management.

[0020] Ceramic electrocardiogram (ECG) units essentially function as high-voltage capacitive loads. Their performance (including cooling temperature range, cooling power, and cycle stability) is highly dependent on the coordinated operation of multiple electrical parameters, including the waveform of the applied electric field, rise / fall time, hold time, cycle frequency, and polarization direction control. This means that simply applying a high-voltage pulse cannot achieve the desired cooling effect; rather, a specialized drive scheme needs to be designed to address the capacitive load characteristics and thermodynamic cycle requirements of the electrocardiogram effect.

[0021] Currently, ceramic card units are mostly driven using a simple high-voltage pulse direct charging and discharging method. The limitations of this method are becoming increasingly apparent as application scenarios demand higher frequency and power density.

[0022] First, during charging, due to the capacitive nature of the ceramic charging unit, directly applying a high-voltage pulse will generate a very large instantaneous charging current (i.e., surge current) at the initial moment. This surge current not only causes high conduction and switching losses in the switching devices of the drive circuit, but also generates additional Joule heat within the ceramic material. This Joule heat, combined with the heat generated by the charging effect itself, partially offsets the net cooling effect of the charging material, reducing the system's effective cooling power. Simultaneously, frequent surge current impacts will accelerate the aging of the drive circuit's switching devices, affecting the long-term reliability of the system.

[0023] Secondly, during the discharge process, traditional solutions typically dissipate the electric field energy stored in the ceramic card unit directly through the discharge resistor or the on-resistance of the switching device. This energy is completely wasted in each cooling cycle, resulting in extremely low system energy utilization efficiency. Especially in high-frequency cyclic drive scenarios, frequent charging and discharging make the cumulative effect of energy waste more significant, and the external power supply pressure increases substantially. In other words, a large amount of input electrical energy is not converted into reversible entropy changes in the effective electric field control process, but is dissipated in the form of charging and discharging losses and driver switching losses.

[0024] Secondly, regarding the timing of control, the electrocardiogram effect thermal cycle of the ceramic electrocardiogram unit includes four stages: "adiabatic heating—heat release—adiabatic cooling—heat absorption," each with different time requirements for the application and removal of the electric field. Simple hard-switching drive methods struggle to independently and precisely control parameters such as charging slope, discharge rate, and high-voltage holding time, leading to a disconnect between the electric field loading / unloading process and the thermal cycling requirements of the electrocardiogram material. Furthermore, improper control during the discharge stage may result in a reverse residual voltage across the ceramic electrocardiogram unit, increasing the risk of material depolarization. Long-term accumulation of this voltage can lead to the attenuation or even failure of the electrocardiogram effect.

[0025] To address the aforementioned issues, several related technical solutions have been proposed. For example, some solutions focus on heat flow organization and pulsed power supply at the level of the ceramic card cooling device, but fail to design a dedicated energy recovery branch for the high-voltage capacitive load characteristics of the ceramic card unit, and do not solve the problem of electric field energy storage recovery and reuse during the discharge phase. They also lack dedicated control timing adapted to the dielectric breakdown margin, polarization maintenance requirements, and dV / dt limitations of the ceramic unit, making it difficult to balance high field loading efficiency, device reliability, and system energy efficiency. Furthermore, some solutions adopt a general capacitive load driving approach. Although energy recovery is involved, the application is mainly to general capacitive loads, and they do not perform parameter and timing coordination design for the electric field cooling cycle of the ceramic card unit. They lack staged control logic that matches the "adiabatic heating—heat release—adiabatic cooling—heat absorption" cycle of the card, and cannot directly meet the comprehensive requirements of the ceramic card cooling system for cooling effect, reliability, and repeated cycle stability.

[0026] In summary, the existing technology lacks a dedicated drive scheme that can achieve discharge energy recovery and reuse, suppress charging and discharging surge current, and adapt to the cooling cycle sequence of the card, while ensuring safe polarization and stable cycling, taking into account the characteristics of ceramic card units as high-voltage capacitive loads. Therefore, this application provides an energy recovery drive circuit and control method adapted to ceramic card units.

[0027] Firstly, as mentioned earlier, in the driving of ceramic card units, how to simultaneously solve the problems of large charging and discharging surge currents, waste of discharging energy, and the disconnect between the driving timing and the card's thermal cycle is the key to improving the energy efficiency of the card cooling system. Traditional high-voltage pulse direct charging and discharging methods generate extremely large instantaneous surge currents in the initial charging stage, leading to increased switching losses and additional Joule heat within the ceramic material; during the discharging stage, the electric field energy stored in the card unit is directly consumed through the bleed resistor or switching devices, resulting in energy waste; furthermore, simple hard-switching drives struggle to precisely control the charging slope, discharging rate, and polarization holding time, failing to match the thermal cycle requirements of the card effect. Therefore, in one embodiment, an energy recovery driving circuit adapted to ceramic card units is provided. For example... Figure 1 As shown, it includes: High-voltage busbar module, used to establish a DC high-voltage busbar; The main drive bridge is connected between the high-voltage bus module and the ceramic card unit, and is used to control the potential at both ends of the ceramic card unit; The resonant charging and discharging branch is connected in series or in parallel between the main drive bridge and the ceramic card unit. The resonant charging and discharging branch includes a resonant inductor, which is used to form a resonant circuit with the equivalent capacitance of the ceramic card unit. The energy recovery branch connects the ceramic card unit and the energy storage element, and is used to transfer the electric field energy stored in the ceramic card unit to the energy storage element during the discharge phase; The detection module is used to collect the terminal voltage of the ceramic card unit, the current of the resonant inductor, the voltage of the high-voltage bus, and the temperature signal. The digital control module is connected to the high-voltage bus module, the main drive bridge, the resonant charging and discharging branch, the energy recovery branch, and the detection module. The digital control module has a built-in timing state machine, which outputs gate signals according to the pre-charge stage, resonant field rise stage, field protection stage, controlled recovery discharge stage, and heat exchange waiting stage executed in sequence, and returns to the resonant field rise stage after the heat exchange waiting stage ends. The resonant field rise stage includes controlling the high-voltage bus module and energy storage element to resonate and charge the ceramic card unit through the resonant inductor; the controlled recovery discharge stage includes controlling the ceramic card unit to discharge to the energy storage element through the resonant inductor.

[0028] Specifically, the high-voltage bus module can use an isolated boost converter to raise the external low-voltage DC power supply to the required high-voltage DC bus voltage, or it can use a flyback converter, voltage doubler rectifier circuit, or external high-voltage power supply to establish the DC high-voltage bus. The voltage level of the DC high-voltage bus is determined according to the operating voltage requirements of the ceramic card unit. For example, when the ceramic card unit requires a 1000V drive voltage, the high-voltage bus module establishes the DC bus voltage at 1000V. The high-voltage bus module also includes a bus capacitor, which is connected in parallel between the positive and negative output terminals of the DC high-voltage bus to smooth the bus voltage and suppress bus voltage ripple.

[0029] In practical implementation, the main drive bridge can adopt a half-bridge structure, a full-bridge structure, or a push-pull structure. Taking the half-bridge structure as an example, the main drive bridge includes a first switching device and a second switching device connected in series between the positive and negative output terminals of the DC high-voltage bus. The common connection point of the first and second switching devices serves as the output terminal of the main drive bridge, connected to one end of the ceramic card unit. The other end of the ceramic card unit is connected to the negative output terminal of the DC high-voltage bus or the output terminal of another drive bridge arm. The switching devices of the main drive bridge can be Si MOSFETs, IGBTs, SiC MOSFETs, or GaN devices. When the voltage level of the DC high-voltage bus exceeds the withstand voltage of a single switching device, each switching arm of the main drive bridge adopts a structure of multiple switching devices connected in series to share the voltage, ensuring that the voltage borne by each switching device does not exceed its withstand voltage.

[0030] Specifically, the resonant charging / discharging branch is connected in series or parallel between the main drive bridge and the ceramic card unit. The resonant charging / discharging branch includes a resonant inductor, which forms a resonant circuit with the equivalent capacitance of the ceramic card unit. When the resonant charging / discharging branch is connected in series between the output of the main drive bridge and the ceramic card unit, the resonant inductor is directly connected in series in the charging current path; when the resonant charging / discharging branch is connected in parallel between the main drive bridge and the ceramic card unit, the resonant inductor is selectively connected to the circuit through switching devices. The inductance value of the resonant inductor is determined based on the equivalent capacitance of the ceramic card unit and the target resonant frequency. During the resonant rise phase, the resonant inductor and the equivalent capacitance of the ceramic card unit form an LC series resonant circuit. This allows the voltage across the ceramic card unit to gradually rise according to the resonance curve during the energy transfer from the high-voltage bus module and energy storage element to the ceramic card unit, rather than a step-like abrupt change, thereby suppressing surge current. During the controlled recycling discharge phase, the same resonant inductor again forms a resonant circuit with the equivalent capacitance of the ceramic card unit, enabling the electric field energy stored in the ceramic card unit to be transferred to the energy storage element in a resonant manner.

[0031] Specifically, the energy recovery branch connects the ceramic card unit and the energy storage element, and is used to transfer the electric field energy stored in the ceramic card unit to the energy storage element during the discharge phase. The energy recovery branch is activated during the controlled recovery discharge phase, providing a path for the discharge current of the ceramic card unit that is different from direct discharge. Through this energy recovery branch, the electric field energy that would have been consumed by the discharge resistor or switching device in the traditional solution is transferred to the energy storage element for storage, avoiding direct energy waste.

[0032] Specifically, the detection module is used to acquire the terminal voltage of the ceramic card unit, the current of the resonant inductor, the voltage of the high-voltage bus, and temperature signals. The detection module includes a voltage sensor, a current sensor, and a temperature sensor. The voltage sensor can use a resistor divider network with an isolation amplifier to acquire the high-voltage DC voltage; the current sensor can use a Hall effect current sensor or a sampling resistor with a differential amplifier to acquire the current; and the temperature sensor can use a thermocouple or a thermistor to acquire the temperature. The detection module converts the acquired analog signals to digital signals and outputs them to the digital control module.

[0033] Specifically, the digital control module is connected to the high-voltage bus module, the main drive bridge, the resonant charging and discharging branch, the energy recovery branch, and the detection module. The digital control module can be implemented using an MCU, FPGA, DSP, or a combination of these devices. The digital control module has a built-in timing state machine that outputs gate signals according to the sequential execution of the pre-charge phase, resonant rise phase, field protection phase, controlled recovery discharge phase, and heat exchange waiting phase, returning to the resonant rise phase after the heat exchange waiting phase. In the pre-charge phase, the digital control module controls the high-voltage bus module to pre-charge the energy storage element through a current-limiting path, establishing an initial voltage for the energy storage element, preparing for the subsequent resonant rise phase. In the resonant rise phase, the digital control module controls the high-voltage bus module and the energy storage element to resonantly charge the ceramic card unit through the resonant inductor, gradually increasing the voltage across the ceramic card unit to the target voltage. In the field protection phase, the digital control module maintains the output state of the main drive bridge, keeping the ceramic card unit at the target voltage for a period of time to complete the polarization process of the card material. During the controlled recovery discharge phase, the digital control module controls the ceramic card unit to discharge to the energy storage element via the resonant inductor, transferring the electric field energy stored in the ceramic card unit to the energy storage element. During the heat exchange waiting phase, the digital control module shuts off all main power switches, allowing the ceramic card unit to complete heat exchange with the cold and hot end structures. After the heat exchange waiting phase ends, the timing state machine returns to the resonant rise phase and begins the next drive cycle.

[0034] Through the resonant circuit composed of the resonant inductor, the energy transfer during the current-limited charging and recovery discharge stages of the rising stage, the storage of recovered energy by the energy storage element, and the sequential control and cyclic return of the five stages by the timing state machine, the electric field loading of the ceramic card unit increases at a controlled slope, thereby suppressing surge current and switching losses. The electric field energy stored during the discharge stage is recovered to the energy storage element, thus avoiding energy waste. Furthermore, the electric field loading, polarization maintenance, energy recovery, and heat exchange form a closed-loop coordination in time, thereby ensuring the integrity and stability of the card's cooling cycle.

[0035] In the process of energy recovery, how to effectively transfer the electric field energy stored in the ceramic card unit to the energy storage element and avoid energy loss during the transfer process is a technical problem that needs to be further solved. Traditional discharge methods directly convert electrical energy into heat energy through resistors, resulting in zero recovery efficiency. To address this problem, in one embodiment, the energy recovery branch includes a bidirectional switch, and the energy storage element is a recovery capacitor or the bus capacitor of the high-voltage bus module. The energy recovery branch uses the bidirectional switch to transfer the electric field energy stored in the ceramic card unit to the recovery capacitor or back to the bus capacitor of the high-voltage bus module via a resonant inductor.

[0036] Specifically, the bidirectional switch can be a bidirectional switching device consisting of two reverse-connected power switching transistors (such as two Si MOSFETs or two IGBTs), or it can be a single bidirectional device (such as a bidirectional thyristor or GaN bidirectional switch). The control terminal of the bidirectional switch is connected to a digital control module, and its turn-on and turn-off are controlled by the gate signal output by the digital control module. When a controlled recycling discharge phase is required, the digital control module outputs a turn-on signal to the bidirectional switch, which then turns on, forming a discharge path from the ceramic capacitor unit through the resonant inductor to the energy storage element. When the recycling discharge process ends, the digital control module outputs a turn-off signal to the bidirectional switch, which then turns off, cutting off the discharge path.

[0037] Specifically, the energy storage element is either a recovery capacitor or the bus capacitor of a high-voltage bus module. When the energy storage element is a recovery capacitor, it is an independent energy storage capacitor, and its capacitance value is determined based on the amount of energy recovered in a single operation and the allowable voltage fluctuation range. One end of the recovery capacitor is connected to the output terminal of the energy recovery branch, and the other end is connected to the negative output terminal of the DC high-voltage bus or system ground. When the energy storage element is the bus capacitor of a high-voltage bus module, the energy recovery branch directly feeds the recovered energy back into the bus capacitor of the DC high-voltage bus, where it is stored together with the existing energy in the bus capacitor.

[0038] Specifically, the energy recovery branch uses a bidirectional switch to transfer the electric field energy stored in the ceramic card unit to the recovery capacitor or back to the bus capacitor of the high-voltage bus module via a resonant inductor. During the controlled recovery discharge phase, after the bidirectional switch is turned on, the ceramic card unit, resonant inductor, and energy storage element (recovery capacitor or bus capacitor) form a series resonant circuit. The electric field energy stored in the ceramic card unit is gradually transferred to the energy storage element through this resonant circuit. Due to the current-limiting effect of the resonant inductor, the peak discharge current is limited to a safe range, avoiding damage to the switching devices and ceramic card unit caused by excessive discharge current.

[0039] Controlled switching on and off of the discharge path is achieved through a bidirectional switch, and a resonant transfer circuit is formed by a resonant inductor and energy storage element, so that the electric field energy stored in the ceramic card unit is efficiently transferred to the recovery capacitor or fed back to the bus capacitor in a resonant manner, avoiding excessive energy loss during the transfer process and realizing the recovery of electric field energy storage.

[0040] To achieve precise timing control and reliable protection functions, the key issues for drive circuit control systems are determining which specific detection signals to acquire and how to utilize these signals for judgment. Traditional drive schemes often only collect the terminal voltage of the ceramic card unit, lacking comprehensive monitoring of resonant current, energy storage status, and temperature, making it difficult to achieve accurate resonant endpoint determination and system protection. To address these issues, in one embodiment, the detection module collects signals including the terminal voltage of the ceramic card unit, the current of the resonant inductor, the voltage of the high-voltage bus, the voltage of the energy storage element, and the hot and cold end temperatures. The detection module inputs all collected signals into the digital control module, which determines the resonant endpoint and recovery cutoff point based on the signals, as well as whether overvoltage protection thresholds, overcurrent protection thresholds, and overtemperature protection thresholds have been reached.

[0041] Specifically, the bidirectional switch can be a bidirectional switching device consisting of two reverse-connected power switching transistors (such as two Si MOSFETs or two IGBTs), or it can be a single bidirectional device (such as a bidirectional thyristor or GaN bidirectional switch). The control terminal of the bidirectional switch is connected to a digital control module, and its turn-on and turn-off are controlled by the gate signal output by the digital control module. When a controlled recycling discharge phase is required, the digital control module outputs a turn-on signal to the bidirectional switch, which then turns on, forming a discharge path from the ceramic capacitor unit through the resonant inductor to the energy storage element. When the recycling discharge process ends, the digital control module outputs a turn-off signal to the bidirectional switch, which then turns off, cutting off the discharge path.

[0042] Specifically, the energy storage element is either a recovery capacitor or the bus capacitor of a high-voltage bus module. When the energy storage element is a recovery capacitor, it is an independent energy storage capacitor, and its capacitance value is determined based on the amount of energy recovered in a single operation and the allowable voltage fluctuation range. One end of the recovery capacitor is connected to the output terminal of the energy recovery branch, and the other end is connected to the negative output terminal of the DC high-voltage bus or system ground. When the energy storage element is the bus capacitor of a high-voltage bus module, the energy recovery branch directly feeds the recovered energy back into the bus capacitor of the DC high-voltage bus, where it is stored together with the existing energy in the bus capacitor.

[0043] Specifically, the energy recovery branch uses a bidirectional switch to transfer the electric field energy stored in the ceramic card unit to the recovery capacitor or back to the bus capacitor of the high-voltage bus module via a resonant inductor. During the controlled recovery discharge phase, after the bidirectional switch is turned on, the ceramic card unit, resonant inductor, and energy storage element (recovery capacitor or bus capacitor) form a series resonant circuit. The electric field energy stored in the ceramic card unit is gradually transferred to the energy storage element through this resonant circuit. Due to the current-limiting effect of the resonant inductor, the peak discharge current is limited to a safe range, avoiding damage to the switching devices and ceramic card unit caused by excessive discharge current.

[0044] Controlled switching on and off of the discharge path is achieved through a bidirectional switch, and a resonant transfer circuit is formed by a resonant inductor and energy storage element, so that the electric field energy stored in the ceramic card unit is efficiently transferred to the recovery capacitor or fed back to the bus capacitor in a resonant manner, avoiding excessive energy loss during the transfer process and realizing the recovery of electric field energy storage.

[0045] To achieve precise timing control and reliable protection functions, the key issues for drive circuit control systems are determining which specific detection signals to acquire and how to utilize these signals for judgment. Traditional drive schemes often only collect the terminal voltage of the ceramic card unit, lacking comprehensive monitoring of resonant current, energy storage state, and temperature, making it difficult to achieve accurate resonant endpoint judgment and system protection. To address these issues, in one embodiment, during the resonant rise stage, the digital control module controls the first set of switches on the main drive bridge to conduct and connects the resonant inductor to the ceramic card unit circuit; the digital control module cuts off the resonant rise stage based on the zero-crossing point of the resonant inductor current, or based on the ceramic card unit's terminal voltage reaching the target voltage.

[0046] Specifically, the terminal voltage of the ceramic card unit reflects the current electric field strength it withstands, serving as the basis for determining whether the target voltage has been reached during the resonant field-raising phase and whether the residual target voltage has been reached during the controlled recycling discharge phase. The current in the resonant inductor reflects the energy flow state in the resonant circuit; its zero-crossing point marks a natural end point of energy transfer in the resonant circuit, providing crucial information for determining the resonance endpoint and recycling cutoff point. The voltage of the high-voltage bus reflects the system's power supply status, used to determine whether the high-voltage bus is within its normal operating range. The voltage of the energy storage element reflects the storage status of the recovered energy, used to determine whether the energy storage element is fully charged and meets the conditions for participating in the next cycle of resonant field-raising. The hot-end and cold-end temperatures reflect the temperature states of the hot and cold ends of the ceramic card unit, used to determine whether heat exchange is complete and whether over-temperature protection is required.

[0047] Specifically, the detection module inputs all collected signals into the digital control module. The digital control module uses these signals to determine the resonant endpoint and recycling cutoff point, as well as whether overvoltage, overcurrent, and overtemperature protection thresholds have been reached. During the resonant rise phase, the digital control module determines whether the resonant rise phase should end (i.e., whether the resonant endpoint has been reached) based on whether the current of the resonant inductor crosses zero or whether the terminal voltage of the ceramic card unit reaches the target voltage. During the controlled recycling discharge phase, the digital control module determines whether the controlled recycling discharge phase should end (i.e., whether the recycling cutoff point has been reached) based on whether the current of the resonant inductor crosses zero, whether the voltage of the energy storage element reaches the upper limit, or whether the residual voltage of the ceramic card unit reaches the preset residual target voltage. Simultaneously, the digital control module compares the terminal voltage of the ceramic card unit with the overvoltage protection threshold, the current of the resonant inductor with the overcurrent protection threshold, and the hot and cold junction temperatures with the overtemperature protection threshold. When any parameter exceeds the corresponding protection threshold, the digital control module immediately executes protection actions (such as shutting off all power switches) to ensure the safety of the ceramic card unit and the drive circuit.

[0048] The detection module collects the above five types of signals and inputs them into the digital control module for comprehensive judgment, so that the endpoint of the resonant rising field and the recovery discharge can be precisely controlled. At the same time, the system has overvoltage, overcurrent and overtemperature protection functions, thereby ensuring the safety of the drive circuit and ceramic card unit in long-term cyclic operation.

[0049] During the resonant rise phase, precisely controlling the start and end times of the resonant rise to achieve efficient energy transfer and safe voltage establishment is a technical issue requiring further refinement. Improper control of the resonant rise's cutoff time may cause the switching devices to turn off under non-zero current conditions, resulting in significant switching losses, or may lead to overshooting of the ceramic energy card unit's terminal voltage, increasing the risk of breakdown. To address these issues, in one embodiment, during the controlled recycling discharge phase, the digital control module disconnects the main charging path and controls the energy recovery branch to conduct; the digital control module terminates the controlled recycling discharge phase based on the zero-crossing point of the resonant inductor's current, or based on the energy storage element's voltage reaching its upper limit, or based on the ceramic energy card unit's residual voltage reaching a preset residual target voltage.

[0050] Specifically, the first set of switches refers to the switching devices in the main drive bridge used to connect one end of the ceramic card unit to the positive or negative output terminal of the DC high-voltage bus. Taking a half-bridge main drive bridge as an example, the first set of switches can be the upper bridge arm switching device connected between the positive output terminal of the DC high-voltage bus and the output terminal of the main drive bridge. When the digital control module controls the upper bridge arm switching device to conduct, the positive output terminal of the DC high-voltage bus is connected to one end of the ceramic card unit through the upper bridge arm switching device and the resonant inductor, and the other end of the ceramic card unit is connected to the negative output terminal of the DC high-voltage bus or system ground, thereby forming a charging circuit. At the same time, the energy storage element is also connected to the charging circuit in parallel or in series through the bidirectional switch in the energy recovery branch, so that the high-voltage bus module and the energy storage element jointly provide energy to the ceramic card unit.

[0051] Specifically, the digital control module cuts off the resonant rise-field stage based on either the zero-crossing of the resonant inductor's current or the reaching of the target voltage at the ceramic card unit's terminals. In the first cutoff method, the digital control module continuously monitors the current waveform of the resonant inductor. Since the resonant rise-field stage is an LC resonant process, the current in the resonant inductor exhibits a sinusoidal waveform. When the current naturally crosses zero, the energy transfer in the resonant circuit reaches a natural boundary point. At this point, the first set of switches is turned off to achieve near-zero current turn-off, thereby reducing switching losses. In the second cutoff method, the digital control module continuously monitors the terminal voltage of the ceramic card unit. When the terminal voltage reaches the preset target voltage, it indicates that the ceramic card unit has reached the required operating electric field strength. At this point, the resonant rise-field stage is immediately cut off, and the first set of switches is turned off, maintaining the voltage across the ceramic card unit near the target voltage. The digital control module can select either of the two cutoff methods as needed, or it can combine the two methods (i.e., cut off when either condition is met).

[0052] By controlling the first set of switches to turn on and connecting the resonant inductor to the circuit, and by cutting off the resonant rise field based on the current crossing zero point or the terminal voltage reaching the target voltage, the resonant rise field stage can end in time at the natural boundary point of energy transfer or when the voltage reaches the set value. This reduces switching losses and avoids overshoot of the ceramic card unit's terminal voltage.

[0053] In the controlled recovery discharge phase, precisely controlling the start and end times of the discharge process to achieve efficient energy recovery while avoiding adverse effects on the ceramic card unit is a technical issue requiring further refinement. Improper discharge termination control may lead to low recovery efficiency, overcharging of the energy storage element, or reverse residual voltage in the ceramic card unit, increasing the risk of depolarization. To address these issues, in one embodiment, when the voltage of the energy storage element exceeds a set value, the digital control module controls the energy storage element to superimpose with the high-voltage bus module during the resonant rise field phase, forming an equivalent loading voltage higher than the output of the high-voltage bus module alone, which is applied to the ceramic card unit.

[0054] Specifically, disconnecting the main charging path means that the digital control module turns off the switching devices (such as the first set of switches) used for charging in the main drive bridge, so that the ceramic card unit is no longer connected to the positive output terminal of the high-voltage bus module. Controlling the energy recovery branch to conduct means that the digital control module outputs a conduction signal to the bidirectional switch in the energy recovery branch, so that the bidirectional switch conducts, forming a discharge path from the ceramic card unit through the resonant inductor to the energy storage element.

[0055] Specifically, the digital control module terminates the controlled recycling discharge phase based on the zero-crossing point of the resonant inductor's current, the energy storage element's voltage reaching its upper limit, or the ceramic card unit's residual voltage reaching a preset residual target voltage. In the first termination method, the digital control module continuously monitors the resonant inductor's current waveform. When the current naturally crosses zero, the energy transfer in the resonant circuit reaches a natural boundary point, at which point the bidirectional switch is turned off to achieve near-zero current turn-off, reducing switching losses. In the second termination method, the digital control module continuously monitors the energy storage element's voltage. When the energy storage element's voltage reaches a preset upper limit, it indicates that the energy storage element has stored sufficient recycled energy or has reached its rated operating voltage. At this point, the controlled recycling discharge phase is immediately terminated, and the bidirectional switch is turned off to prevent overcharging of the energy storage element. In the third termination method, the digital control module continuously monitors the terminal voltage of the ceramic card unit. When the terminal voltage of the ceramic card unit drops to the preset residual target voltage, it indicates that most of the electric field energy stored in the ceramic card unit has been transferred to the energy storage element. At this point, the controlled recycling discharge stage is immediately terminated, and the bidirectional switch is turned off. By controlling the residual voltage within the preset residual target voltage, unwanted reverse electric fields in the ceramic card unit can be avoided, thereby reducing the risk of material depolarization. The digital control module can select any one of the three termination methods mentioned above, or combine multiple methods (terminating when any condition is met).

[0056] By disconnecting the main charging path and controlling the conduction of the energy recovery branch, and terminating the recovery discharge based on the current zero-crossing point, the upper limit of the energy storage element voltage, or the residual target voltage, the controlled recovery discharge stage can end in time at the natural boundary point of energy transfer, when the energy storage element is fully charged, or when the residual voltage drops to a safe value. This not only improves the recovery efficiency but also avoids the risks of overcharging the energy storage element and reverse depolarization of the ceramic card unit.

[0057] When ceramic card units require higher driving electric field strength but the external input voltage is limited, how to provide higher transient loading voltage to the ceramic card units without increasing the external input voltage is a technical problem that needs further solutions. In traditional solutions, increasing the loading voltage can only be achieved by increasing the external power supply voltage or using a boost converter, but this increases system cost and size. To address the above problem, in one embodiment, there are multiple ceramic card units, which form an array and share the same high-voltage bus; each ceramic card unit is configured with a local power switch, a local sampling channel, and a logic address; the digital control module performs staggered driving of each ceramic card unit, so that adjacent ceramic card units charge and discharge at off-peak times, and preferentially allocates the energy recovered by the previous ceramic card unit to the energy storage element to the next ceramic card unit to be driven.

[0058] Specifically, during the controlled recovery discharge phase, the energy storage element (such as a recovery capacitor) stores the electric field energy recovered from the ceramic card unit, and the voltage across its terminals represents the amount of energy recovered. In the subsequent resonant rise phase, if the voltage of the energy storage element exceeds a certain set value (which can be preset according to actual needs, for example, as a percentage of the high-voltage bus voltage), it indicates that the energy storage element has stored sufficient energy to participate in charging the ceramic card unit.

[0059] Specifically, the digital control module controls the switching timing of the main drive bridge and the conduction timing of the bidirectional switches in the energy recovery branch, enabling the energy storage element and the high-voltage bus module to be connected in series or parallel to supply power to the ceramic card unit. When the energy storage element and the high-voltage bus module are connected in series, the total voltage applied to the ceramic card unit is the sum of the output voltage of the high-voltage bus module and the voltage of the energy storage element. Therefore, the equivalent applied voltage is higher than the voltage output by the high-voltage bus module alone. For example, when the output voltage of the high-voltage bus module is 500V and the voltage of the energy storage element is 200V, the total voltage applied to the ceramic card unit can reach 700V through series connection.

[0060] By detecting the voltage of the energy storage element and controlling the superposition of the energy storage element and the high-voltage bus module when it exceeds the set value, the recovered energy can provide a higher transient loading voltage for the ceramic card unit without increasing the external input voltage, thereby improving the electric field response intensity of the ceramic card unit.

[0061] In scenarios requiring simultaneous independent control of multiple ceramic card units (such as multi-point temperature control in chip-based local thermal management), achieving efficient driving and energy reuse of arrayed ceramic card units is a technical problem that needs further resolution. Traditional solutions require an independent driving power supply for each card unit, resulting in complex and costly systems, and preventing energy sharing and reuse between units. To address these issues, in one embodiment, multiple ceramic card units are used, forming an array and sharing the same high-voltage bus. Each ceramic card unit is configured with a local power switch, a local sampling channel, and a logic address. A digital control module interleaves the driving of each ceramic card unit, allowing adjacent units to charge and discharge at off-peak times, and preferentially allocating energy recovered from the previous unit to the energy storage element to the next unit to be driven.

[0062] Specifically, local power switches are used to independently control the connection and disconnection of the corresponding ceramic card unit with the high-voltage bus, resonant inductor, and energy recovery branch, allowing each ceramic card unit to be independently selected and driven. Local sampling channels are used to independently acquire parameters such as terminal voltage, current, and temperature of the corresponding ceramic card unit, enabling independent monitoring of the operating status of each unit. Logical addresses are used to uniquely identify each ceramic card unit in the array, allowing the digital control module to control and schedule specific ceramic card units through addressing.

[0063] Specifically, the digital control module interleaves the driving of each ceramic card unit, allowing adjacent ceramic card units to charge and discharge at off-peak times. Interleaving the driving means that the digital control module sequentially starts the driving cycle of each ceramic card unit according to a certain phase difference, so that different ceramic card units are in different driving stages at the same time. For example, when the first ceramic card unit is in the field-holding stage, the second ceramic card unit can be in the resonant field-raising stage, and the third ceramic card unit can be in the controlled recycling discharge stage. Through interleaving the driving, the charging and discharging currents of each ceramic card unit are staggered in time, thereby reducing current ripple and voltage fluctuations on the high-voltage bus and reducing the filtering pressure on the bus capacitor. Simultaneously, because the charging and discharging times of each ceramic card unit are staggered, local heat accumulation is alleviated, which is beneficial to the overall thermal management of the array.

[0064] Specifically, the energy recovered by the previous ceramic energy storage unit is preferentially allocated to the next ceramic energy storage unit to be driven. Similarly, the energy recovered by the previous ceramic energy storage unit during the controlled recovery discharge phase is preferentially allocated to the next ceramic energy storage unit to be driven for charging during its resonant rise phase. This array-level energy reuse mechanism of "recovery-redistribution-reloading" ensures that the recovered energy is fully utilized within the array, further reducing the net input energy obtained by the entire array from the external high-voltage bus.

[0065] By sharing the same high-voltage bus with multiple ceramic card units and configuring local power switches, local sampling channels, and logic addresses respectively, combined with the interleaved drive and priority allocation of recovered energy by the digital control module, the arrayed ceramic card units can be independently selected and scheduled, the charging and discharging currents are staggered in time to reduce bus ripple and local heat accumulation, and the recovered energy is preferentially allocated to the next unit to be driven within the array, thereby reducing the net input energy obtained by the array from the external bus.

[0066] Secondly, in the drive control process of the ceramic card unit, how to achieve energy recovery and cyclic drive through specific control steps is the core issue at the methodological level. Traditional high-voltage pulse drive methods only have two simple stages: charging and discharging. They lack a stage division that matches the card's thermal cycle (adiabatic heating—heat release—adiabatic cooling—heat absorption), leading to a disconnect between electric field loading and thermal cycling. Therefore, in one embodiment, an energy recovery drive control method adapted to the ceramic card unit is provided, such as… Figure 2 As shown, it includes the following steps: Step S1: Charge the energy storage element until the voltage of the energy storage element reaches a preset threshold. Step S2: Control the high-voltage bus module and energy storage element to resonate and charge the ceramic card unit through the resonant inductor; Step S3: Maintain the ceramic card unit at the target voltage for a preset hold time; Step S4: Control the ceramic card unit to discharge to the energy storage element through the resonant inductor; Step S5: Turn off all main power switches to allow the ceramic card unit to complete heat exchange; Steps S2 to S5 are executed sequentially in a loop, and after step S5 is completed, the process returns to step S2.

[0067] Specifically, step S1 is the initialization step, executed once during system startup. The digital control module detects the current voltage of the energy storage element. When the voltage of the energy storage element is lower than a preset threshold, the digital control module controls the high-voltage bus module to charge the energy storage element through a current-limiting path, enabling the energy storage element to establish an initial voltage. The preset threshold can be determined based on the type of energy storage element and the system's operating voltage, for example, set to 50% of the high-voltage bus voltage or a fixed voltage value. When the voltage of the energy storage element reaches the preset threshold, charging of the energy storage element stops, and the system proceeds to step S2. After the system enters a stable cycle, step S1 is no longer executed repeatedly. Step S1 is only executed again when the voltage of the energy storage element falls below the preset threshold again (such as after a long-term shutdown and restart or after a fault is recovered).

[0068] Specifically, in step S2, the digital control module controls the corresponding switch of the main drive bridge to conduct and connects the resonant inductor to the ceramic card unit circuit. Simultaneously, it controls the bidirectional switch in the energy recovery branch to conduct (if the energy storage element is connected through the energy recovery branch), allowing the high-voltage bus module and the energy storage element to charge the ceramic card unit together through the resonant inductor. Since the resonant inductor and the equivalent capacitance of the ceramic card unit form an LC resonant circuit, the voltage across the ceramic card unit gradually increases according to the resonance curve during charging, rather than a step-like jump, thus suppressing surge current. At the end of step S2, the voltage across the ceramic card unit reaches the target voltage.

[0069] Specifically, in step S3, the digital control module shuts down the resonant charging and discharging branch (i.e., turns off the switching devices in the branch where the resonant inductor is located), maintaining only the output state of the main drive bridge, so that the voltage across the ceramic card unit remains near the target voltage. The field-holding time can be set according to the relaxation time of the ceramic card material, heat exchange requirements, and cooling mode, for example, set to a value between 1 millisecond and 100 milliseconds. During the field-holding period, the ceramic card material completes the polarization process under the action of the electric field, achieving adiabatic heating.

[0070] Specifically, in step S4, the digital control module disconnects the main charging path (i.e., turns off the switching devices used for charging in the main drive bridge) and controls the energy recovery branch to conduct, allowing the ceramic card unit to discharge to the energy storage element through the resonant inductor. Since the resonant inductor and the equivalent capacitance of the ceramic card unit form an LC resonant circuit, the electric field energy stored in the ceramic card unit is gradually transferred to the energy storage element in a resonant manner during the discharge process, and the peak value of the discharge current is limited to a safe range.

[0071] Specifically, in step S5, the digital control module shuts off all main power switches (including all switching devices in the main drive bridge and the bidirectional switches in the energy recovery branch), putting the ceramic card unit in an open-circuit state. At this time, the ceramic card unit exchanges heat with the cold and hot end structures, completing the heat absorption and release process. The duration of heat exchange can be adaptively adjusted according to the cycle frequency, thermal switching state, or temperature difference.

[0072] Specifically, steps S2 to S5 are executed sequentially in a loop, and the system returns to step S2 after step S5 is completed. After completing a full drive cycle (resonance field rise → field maintenance → recovery discharge → heat exchange waiting), the system automatically returns to step S2 and begins the next drive cycle.

[0073] By initializing and charging the energy storage element, controlling the high-voltage bus module and the energy storage element to resonate and charge the ceramic card unit through the resonant inductor to suppress surge current, maintaining the target voltage to keep the field holding time to complete polarization, controlling the ceramic card unit to discharge to the energy storage element through the resonant inductor to recover the electric field stored energy, and turning off all main power switches to allow the ceramic card unit to complete heat exchange, and executing steps S2 to S5 in sequence and returning to step S2 after step S5 is completed, the resonant field raising, field holding, recovery discharge and heat exchange waiting constitute an uninterrupted periodic cooling cycle, realizing the recovery of discharge energy and cyclic drive.

[0074] In the resonant charging process of step S2, how to precisely control the end time of charging to achieve efficient charging and low-loss switching is a technical problem that requires further refinement. Improper charging cut-off control may lead to insufficient charging affecting the cooling effect, charging overshoot increasing the risk of breakdown, or the switching device turning off under non-zero current conditions, resulting in significant switching losses. To address these issues, in one embodiment, in step S2, resonant charging is cut off based on the zero-crossing point of the resonant inductor's current, or based on the ceramic card unit's terminal voltage reaching the target voltage.

[0075] Specifically, in the first cutoff method, the digital control module continuously monitors the current waveform of the resonant inductor. Since step S2 is an LC resonant charging process, the current of the resonant inductor exhibits a sinusoidal waveform. When the current naturally crosses zero, the energy transfer in the resonant circuit reaches a natural boundary point. At this point, turning off the switching devices in the charging circuit can achieve near-zero current turn-off, thereby reducing switching losses and improving system efficiency.

[0076] Specifically, in the second cutoff method, the digital control module continuously monitors the terminal voltage of the ceramic card unit. When the terminal voltage reaches the preset target voltage, it indicates that the ceramic card unit has reached the required working electric field strength. At this time, the resonant charging is immediately cut off, the switching devices in the charging circuit are turned off, and the ceramic card unit enters the field protection stage.

[0077] By stopping resonant charging based on the zero-crossing point of the resonant inductor current or the target voltage of the ceramic card unit, the resonant charging phase can end in time at the natural boundary point of energy transfer or when the voltage reaches the set value. This reduces switching losses and avoids undercharging or overcharging.

[0078] In step S4, precisely controlling the end time of discharge to achieve efficient energy recovery and avoid adverse effects on the ceramic card unit is a technical problem that requires further refinement. Improper discharge termination control may lead to low recovery efficiency, overcharging of the energy storage element, or reverse residual voltage in the ceramic card unit, increasing the risk of depolarization. To address these issues, in one embodiment, in step S4, discharge is terminated based on the zero-crossing of the resonant inductor current, the energy storage element voltage reaching its upper limit, or the residual voltage of the ceramic card unit reaching a preset residual target voltage.

[0079] Specifically, in the first termination method, the digital control module continuously monitors the current waveform of the resonant inductor. When the current naturally crosses zero, the energy transfer in the resonant circuit reaches a natural boundary point. At this time, the switching devices in the discharge circuit are turned off to achieve near-zero current turn-off, reducing switching losses.

[0080] Specifically, in the second termination method, the digital control module continuously monitors the voltage of the energy storage element. When the voltage of the energy storage element reaches the preset upper limit, it indicates that the energy storage element has stored enough recovered energy or has reached its rated operating voltage. At this time, the discharge is immediately terminated and the switching devices in the discharge circuit are turned off to avoid overcharging of the energy storage element.

[0081] Specifically, in the third termination method, the digital control module continuously monitors the terminal voltage of the ceramic card unit. When the terminal voltage of the ceramic card unit drops to the preset residual target voltage, it indicates that most of the electric field energy stored in the ceramic card unit has been transferred to the energy storage element. At this point, the discharge is immediately terminated, and the switching devices in the discharge circuit are turned off. By controlling the residual voltage within the preset residual target voltage, unwanted reverse electric fields can be avoided in the ceramic card unit, thereby reducing the risk of material depolarization and ensuring the reliability of the ceramic card unit during long-term cyclic operation.

[0082] By terminating the discharge based on the zero-crossing point of the resonant inductor current, the upper limit of the energy storage element voltage, or the residual voltage of the ceramic card unit reaching a preset residual target voltage, the controlled recycling discharge stage can end in time at the natural boundary point of energy transfer, when the energy storage element is fully charged, or when the residual voltage drops to a safe value. This reduces switching losses and avoids the risks of overcharging the energy storage element and reverse depolarization of the ceramic card unit.

[0083] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0084] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0085] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. An energy recovery drive circuit adapted to a ceramic card unit, characterized in that, include: High-voltage busbar module, used to establish a DC high-voltage busbar; The main drive bridge is connected between the high-voltage bus module and the ceramic card unit, and is used to control the potential at both ends of the ceramic card unit; A resonant charging and discharging branch is connected in series or in parallel between the main drive bridge and the ceramic card unit. The resonant charging and discharging branch includes a resonant inductor, which is used to form a resonant circuit with the equivalent capacitance of the ceramic card unit. An energy recovery branch is connected between the ceramic card unit and the energy storage element, and is used to transfer the electric field energy stored in the ceramic card unit to the energy storage element during the discharge phase; The detection module is used to collect the terminal voltage of the ceramic card unit, the current of the resonant inductor, the voltage of the high-voltage bus, and the temperature signal. A digital control module is connected to the high-voltage bus module, the main drive bridge, the resonant charging and discharging branch, the energy recovery branch, and the detection module. The digital control module has a built-in timing state machine. This timing state machine outputs gate signals according to the sequential execution of a pre-charge stage, a resonant rise stage, a field-maintaining stage, a controlled recovery discharge stage, and a heat exchange waiting stage. After the heat exchange waiting stage, it returns to the resonant rise stage. The resonant rise stage includes controlling the high-voltage bus module and the energy storage element to resonate and charge the ceramic charging unit via the resonant inductor. The controlled recovery discharge stage includes controlling the ceramic charging unit to discharge to the energy storage element via the resonant inductor.

2. The energy recovery drive circuit for the ceramic card unit according to claim 1, characterized in that, The energy recovery branch includes a bidirectional switch, and the energy storage element is a recovery capacitor or the bus capacitor of the high-voltage bus module; the energy recovery branch transfers the electric field energy stored in the ceramic card unit to the recovery capacitor or back to the bus capacitor of the high-voltage bus module through the bidirectional switch.

3. The energy recovery drive circuit for the ceramic card unit according to claim 1, characterized in that, The signals collected by the detection module include the terminal voltage of the ceramic card unit, the current of the resonant inductor, the voltage of the high-voltage bus, the voltage of the energy storage element, the hot end temperature, and the cold end temperature. The detection module inputs all the collected signals into the digital control module, which determines the resonance endpoint and the recovery cutoff point based on the signals, as well as whether the overvoltage protection threshold, overcurrent protection threshold, and overtemperature protection threshold have been reached.

4. The energy recovery drive circuit for the ceramic card unit according to claim 1 or 3, characterized in that, During the resonant rise stage, the digital control module controls the first set of switches of the main drive bridge to turn on and connects the resonant inductor to the ceramic card unit circuit; the digital control module cuts off the resonant rise stage according to the zero-crossing point of the current of the resonant inductor, or cuts off the resonant rise stage according to the terminal voltage of the ceramic card unit reaching the target voltage.

5. The energy recovery drive circuit for the ceramic card unit according to claim 1 or 3, characterized in that, During the controlled recycling discharge phase, the digital control module disconnects the main charging path and controls the energy recovery branch to be turned on. The digital control module terminates the controlled recycling discharge stage based on the zero-crossing point of the current of the resonant inductor, or based on the voltage of the energy storage element reaching the upper limit value, or based on the residual voltage of the ceramic card unit reaching a preset residual target voltage.

6. The energy recovery drive circuit for the ceramic card unit according to claim 1, characterized in that, When the voltage of the energy storage element is higher than the set value, the digital control module controls the energy storage element and the high-voltage bus module to be superimposed during the resonant rising field stage, forming an equivalent loading voltage higher than that output by the high-voltage bus module alone, which is applied to the ceramic card unit.

7. The energy recovery drive circuit for the ceramic card unit according to claim 1, characterized in that, The number of ceramic card units is multiple, and the multiple ceramic card units form an array and share the same high-voltage bus; each ceramic card unit is configured with a local power switch, a local sampling channel and a logic address; the digital control module performs interleaved driving on each ceramic card unit, so that adjacent ceramic card units charge and discharge at off-peak times, and the energy recovered by the previous ceramic card unit to the energy storage element is preferentially allocated to the next ceramic card unit to be driven.

8. An energy recovery drive control method adapted to a ceramic card unit, characterized in that, Includes the following steps: Step S1: Charge the energy storage element until the voltage of the energy storage element reaches a preset threshold. Step S2: Control the high-voltage bus module and the energy storage element to resonate and charge the ceramic card unit through the resonant inductor; Step S3: Maintain the ceramic card unit at the target voltage for a preset holding time; Step S4: Control the ceramic card unit to discharge to the energy storage element through the resonant inductor; Step S5: Turn off all main power switches to allow the ceramic card unit to complete heat exchange; Steps S2 to S5 are executed sequentially in a loop, and after step S5 is completed, the process returns to step S2.

9. The energy recovery drive control method for the ceramic card unit according to claim 8, characterized in that, In step S2, resonant charging is stopped when the current of the resonant inductor crosses zero, or when the terminal voltage of the ceramic card unit reaches the target voltage.

10. The energy recovery drive control method for the ceramic card unit according to claim 8, characterized in that, In step S4, the discharge is terminated when the current of the resonant inductor crosses zero, or when the voltage of the energy storage element reaches the upper limit, or when the residual voltage of the ceramic card unit reaches a preset residual target voltage.

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