An adaptive dual closed-loop charging control method and charger

Abstract

The present invention belongs to the field of nickel-cadmium battery chargers, specifically an adaptive dual-closed-loop charging control method and charger. The charger charges nickel-cadmium batteries in multiple charging modes, including constant current, constant voltage (high charging voltage limit), and floating charge (low charging voltage limit). When switching between constant current and constant voltage charging modes, a constant current loop and a constant voltage loop are controlled in parallel, adaptively switching to the corresponding mode based on the external battery charge state. The voltage loop and current loop are independent of each other, allowing for a higher cutoff frequency to be designed, improving response speed while also enabling seamless switching.

Description

Technical Field

[0001] The invention belongs to the field of nickel-cadmium battery chargers, and in particular relates to an adaptive double-closed-loop charging control method and a charger. Background Art

[0002] Nickel-cadmium battery chargers typically implement a series loop structure consisting of an outer voltage loop and an inner current loop to switch from constant current to constant voltage charging mode. The output of the voltage loop serves as a reference for the current loop. However, this series loop design prevents independent design of the two short-circuit cutoff frequencies, hindering the charger's dynamic response. Furthermore, the current value is affected by the saturation voltage of the voltage loop output, resulting in low accuracy. When designing mode switching, chargers typically only consider the unidirectional switching logic from constant current to constant voltage to float charge, neglecting the logic for returning from float charge to constant voltage mode. For nickel-cadmium batteries, after entering float charge mode, the charger's output voltage rapidly drops to the float voltage limit, causing the battery voltage to slowly decrease, halting charging. When the battery voltage drops below the charger's float voltage limit, the difference in rate of decrease causes the charger to output a pulsed charging current, causing the charger to return to the higher constant voltage limit and, in turn, a higher pulsed charging current. The charger then attempts to recharge the battery, but since the battery is fully charged, it quickly re-enters float charge mode, resulting in periodic pulsed current, which reduces the battery's service life. Summary of the Invention

[0003] The present invention provides an adaptive dual-closed-loop charging control method and charger. Both the constant current charging mode and the constant voltage charging mode have relatively fast dynamic response, and the charging current achieves relatively high control accuracy. At the same time, it solves the problem of periodic inrush current when the floating charging mode returns to the constant voltage charging mode.

[0004] Technical Solution

[0005] An adaptive dual closed-loop charging control method and charger

[0006] The present invention provides an adaptive dual-closed-loop charging control method, which is implemented based on a nickel-cadmium battery charging control circuit. The nickel-cadmium battery charging control circuit includes a power converter, a filter, a current detection subcircuit, a voltage detection subcircuit, a current loop subcircuit, a voltage loop subcircuit, a battery temperature detection subcircuit, a PWM generation subcircuit, an air cooling overtemperature fault detection subcircuit, and a mode switching subcircuit.

[0007] The power converter is used to convert the input power voltage and output the required output voltage and output current; the output voltage and output current are filtered to remove ripple signals; the filtered output current enters the current detection subcircuit for detection, converted into the required voltage signal, and then output to the current loop subcircuit and the mode switching subcircuit; the filtered output voltage enters the voltage detection subcircuit for detection, converted into the required voltage signal, and then output to the voltage loop subcircuit; the current loop subcircuit modulates the converted output current signal with the current reference signal from the mode switching subcircuit and outputs the modulated signal to the cathode of the diode connected to the output of the voltage loop subcircuit; the voltage loop subcircuit modulates the converted output voltage signal with the voltage reference signal from the mode switching subcircuit and outputs the modulated signal to the PWM generation circuit and the anode of the diode connected to the current loop subcircuit; the PWM generation circuit processes the signal output by the voltage loop subcircuit to obtain a drive signal and sends it to the power converter; the battery temperature detection subcircuit converts the detected battery temperature into the required voltage signal and outputs it to the mode switching subcircuit; the air cooling and over-temperature fault detection subcircuit converts air cooling equipment fault and over-temperature fault into logic signals and outputs them to the mode switching subcircuit;

[0008] The mode switching subcircuit includes a constant voltage to floating charge mode recognition circuit, a floating charge to constant voltage mode recognition circuit, a normal or fault mode recognition circuit, a voltage loop reference switching circuit, and a current loop reference switching circuit. The constant voltage to floating charge mode recognition circuit performs a logical operation on the converted output current signal and the converted battery temperature and outputs the result to the voltage loop reference switching circuit; the floating charge to constant voltage mode recognition circuit also performs a logical operation on the converted output current signal and the converted battery temperature and outputs the result to the voltage loop reference switching circuit; the voltage loop reference switching circuit processes the two input mode recognition signals and outputs them to the voltage loop subcircuit; the normal or fault mode recognition circuit processes the logic signals output by the air cooling and over-temperature fault detection subcircuits and outputs them to the current loop reference switching circuit, which then processes the signals and outputs them to the current loop subcircuit.

[0009] Furthermore, when the normal or fault mode recognition circuit identifies that the output logic of the air cooling or over-temperature fault detection circuit is a normal mode, the circuit outputs a logic 0 to the current loop reference switching circuit. The current loop reference switching circuit receives the logic 0 output by the normal or fault mode recognition circuit and outputs a signal to set the charging current to C to the current loop sub-circuit. When the normal or fault mode recognition circuit identifies that the output logic of the air cooling or over-temperature fault detection circuit is a fault mode, the circuit outputs a logic 1 to the current loop reference switching circuit. The current loop reference switching circuit receives the logic 1 output by the normal or fault mode recognition circuit and outputs a signal to set the charging current to C0 to the current loop sub-circuit.

[0010] Wherein, C is 90%-110% of the capacity R in the rated capacity RAh of the selected nickel-cadmium battery, and C0 is 30%-50% of the charging current value C set by the current loop reference switching circuit in normal mode;

[0011] Furthermore, the constant voltage to floating charge mode identification circuit includes a current value judgment circuit 1, a current value judgment circuit 2, a timer 1 circuit, a battery temperature judgment circuit 1, and an OR logic gate. The current value judgment circuit 1 judges the converted output current signal and outputs it to the OR logic gate. The judgment logic is that when the output current is lower than the current value C1, it outputs a logic 1. The current value judgment circuit 2 judges the converted output current signal and outputs it to the timer 1 circuit. The judgment logic is that when the output current is higher than the current value C2, it outputs a logic 1. After being processed by the timer 1 circuit, the circuit output is output to the OR logic gate. The logic of the timer 1 circuit is that when the duration of the output logic 1 of the current value judgment circuit 2 is greater than T1, the timer 1 circuit outputs a logic 1. The battery temperature judgment circuit 1 judges the converted battery temperature signal and outputs it to the OR logic gate. The judgment logic is that when the battery temperature is lower than M1, the output is a logic 1.

[0012] Among them, C1 is 10%-20% of the charging current value C set by the current loop reference switching circuit in normal mode; C2 is 80%-90% of the charging current value C set by the current loop reference switching circuit in normal mode; T1 is 1.2-2 times the total time T required to fully charge the empty battery to the floating charge mode in normal mode; the total time T is the sum of the constant current mode time and the constant voltage mode time during the charging process of the empty battery; M1 is the low temperature point when the battery discharge performance is lower than 80% of the normal temperature of 25°C.

[0013] Furthermore, the floating charge to constant voltage mode recognition circuit includes a current value judgment circuit 3, a battery temperature judgment circuit 2, a timer 2 circuit, and an AND logic gate. The current value judgment circuit 3 judges the converted output current signal and outputs it to the AND logic gate and the timer 2 circuit. The judgment logic is that when the output current is higher than the current value C3, the output is a logic 1. The timer 2 circuit logic is that when the output logic 1 of the current value judgment circuit 3 lasts longer than T2, the timer 2 circuit outputs a logic 1. The battery temperature judgment circuit 2 judges the converted battery temperature signal and outputs it to the OR logic gate. The judgment logic is that when the battery temperature is higher than M2, the output is a logic 1.

[0014] Among them, C3 is 70%-80% of the charging current value C set by the current loop reference switching circuit in normal mode; T2 should be greater than the duration of the constant voltage charging mode in normal mode; M2 is the low temperature point when the battery discharge performance is higher than 90% of the normal temperature of 25°C.

[0015] Furthermore, the filter should be a high-frequency filter. The purpose of selecting a high-frequency filter is to obtain smoother output current and output voltage signals.

[0016] Furthermore, the current detection sub-circuit should be selected to have a bandwidth higher than the switching frequency bandwidth of the power converter to ensure a fast dynamic response to the output current.

[0017] Furthermore, the regulator design in the current loop subcircuit should meet the criterion of current loop stability, and a PI regulator is preferably used;

[0018] Furthermore, the regulator design in the voltage loop subcircuit should meet the voltage loop stability criterion.

[0019] PID regulator is preferred;

[0020] Furthermore, the power converter should be in a DC-DC conversion form or an AC-DC conversion form.

[0021] Technical Effects

[0022] The present invention achieves independent control of the voltage and current loops by outputting the current detection and voltage detection subcircuits to the current loop and voltage loop subcircuits, respectively. The outputs of the voltage loop and current loop are then connected via diodes, forming a parallel voltage and current loop structure. This improves dynamic response and current control accuracy. The mode switching subcircuit outputs both voltage limiting switching signals for different charging modes based on the battery charge level and constant current switching signals for different operating conditions. It also incorporates both forward and reverse mode switching logic, better matching the battery's charging characteristics and extending battery life. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Charger control block diagram;

[0024] Figure 2 Constant voltage to floating charge mode recognition circuit;

[0025] Figure 3 Floating charge to constant voltage mode recognition circuit;

[0026] Figure 4 Current loop subcircuit and voltage loop subcircuit. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to the following embodiments. The following are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] When switching from constant voltage to float charge mode, conventional charger designs only consider forward switching. When the charging current drops to a certain value, the battery switches from constant voltage to float charge. When switching back from float charge to constant voltage, the control method is not tailored to the battery's characteristics. When switching from float charge to constant voltage mode, the present invention considers the slow drop in battery voltage after a full charge of a nickel-cadmium battery, requiring a sufficiently large charging current and a sufficiently long duration to avoid high current shocks to the battery caused by erroneous mode switching.

[0029] The battery charger is used to charge the battery in multiple modes and achieve better charging effect and longer working life of the battery through a mode switching design that matches the battery characteristics.

[0030] The present invention is further described in detail below with reference to the embodiments.

[0031] The rated capacity RAh of the selected nickel-cadmium battery is 44Ah. Under normal conditions, the total time T required for the float charge mode to fully charge the empty battery is 80 minutes.

[0032] The voltage loop and current loop in the parallel dual loop are independent, connected in parallel through a diode to generate a feedback signal that is output to the PWM generation circuit. When in constant current charging mode, the output current is equal to the current loop reference value, the output voltage is lower than the voltage loop reference value, the voltage loop output is forward saturated, the diode conducts, and the feedback signal follows the current loop output. When the output voltage gradually rises to the voltage loop reference value, the voltage loop begins to exit saturation, the current loop begins forward saturation, the diode cuts off, and the feedback signal follows the voltage loop output, entering constant voltage mode.

[0033] When charging an empty battery, the air cooling and over-temperature detection sub-circuit outputs a normal state signal when it detects an air cooling fault or an over-temperature fault. The normal or fault identification circuit recognizes this normal state signal and outputs a logic 0 to the current loop reference switching circuit. The current loop reference switching circuit outputs a signal to set the charging current to 46A to the current loop sub-circuit, thereby controlling the output current to a constant current of 46A.

[0034] When the air cooling and over-temperature detection sub-circuit detects an air cooling fault or an over-temperature fault, it outputs a fault status signal. The normal or fault identification circuit recognizes this fault status signal and outputs a logic 1 to the current loop reference switching circuit. The current loop reference switching circuit outputs a signal to set the charging current to 15A to the current loop sub-circuit, thereby controlling the output current to a constant current of 15A.

[0035] Under normal conditions, the charger charges the nickel-cadmium battery at a constant current of 46A. During this time, the current loop operates, and the voltage output is saturated. Current Value Detection Circuit 1 detects that the output current is above 7.5A and outputs a logic 0. Current Value Detection Circuit 2 detects that the output current is above 40A and outputs a logic 1. Timer 1 detects that the output of Current Value Detection Circuit 2 is logic 1 and begins timing. If the timing does not reach 120 minutes, Timer 1 outputs a logic 0. The battery temperature exceeds -15°C, and Battery Temperature Detection Circuit 1 outputs a logic 0. The OR logic gate in the constant-voltage-to-float charge mode identification circuit outputs a logic 0, and the voltage loop reference switching circuit sets the output voltage limit to the constant voltage limit. As the battery charge gradually increases, the output voltage gradually rises. When the output voltage reaches the constant voltage limit, the voltage loop gradually exits saturation. As charging continues, the battery voltage further increases, maintaining the constant voltage limit, and the output current begins to decrease. When the output current drops to 7.5A, the output of Current Value Detection Circuit 1 changes to a logic 1, and the voltage loop reference switching circuit sets the output voltage limit to the float charge limit, entering float charge mode. Before entering the float charge mode, the battery voltage is close to the constant voltage limit value of the output voltage.

[0036] At the same time, before the output logic of the current value judgment 1 circuit changes to 1, the output logic of the timer 1 circuit reaches 120 minutes, and the voltage loop reference switching circuit sets the output voltage limit value to the floating charge limit value, entering the floating charge mode.

[0037] At the same time, before the output logic of the current value judgment 1 circuit changes to 1, the battery temperature judgment 1 circuit outputs logic 1 when it judges that the battery temperature is lower than -15°C, and the voltage loop reference switching circuit sets the output voltage limit value to the floating charge limit value, entering the floating charge mode.

[0038] After entering float charge mode, the output voltage rapidly drops to the float charge limit. The battery voltage changes more slowly, slowly decreasing from near the constant voltage limit. At this point, the battery is essentially fully charged. In emergency conditions, the battery supplies power to critical onboard loads. The battery voltage begins to drop as the battery discharges, and the charger begins charging. Initially, the output current is low. In the float charge to constant voltage mode identification circuit, the current value determination circuit 3 determines that the output current is less than 35A and outputs a logic 0. Timer 2 circuit has not yet started, and its output is a logic 0. Battery temperature determination circuit 2 determines that the battery temperature is above -10°C and outputs a logic 1. The AND logic gate in the float charge to constant voltage mode identification circuit outputs a logic 0, and the voltage loop reference switching circuit sets the output voltage limit to the float charge limit. As the battery charge decreases, the charging current begins to increase. When the battery value judgment circuit 3 judges that the output current is higher than 35A, the output logic is 1; the timer 2 circuit starts timing, and when the timing time reaches 10 minutes, the output logic is 1; the AND logic gate in the float charge to constant voltage mode recognition circuit outputs logic 1, and the voltage loop reference switching circuit sets the output voltage limit value to the constant voltage limit value to achieve fast charging of the battery.

[0039] At the same time, during the floating charge mode, the battery temperature judgment circuit 2 determines that the battery temperature is always below -10°C, then the output logic of the AND logic gate in the floating charge to constant voltage mode identification circuit is always 0, and the voltage loop reference switching circuit sets the output voltage limit value to the floating charge limit value to extend the battery's low temperature service life.

[0040] Example 2

[0041] The adaptive dual closed-loop charging control method and charger include the following steps:

[0042] The present invention provides an adaptive dual-closed-loop charging control method, which is implemented based on a nickel-cadmium battery charging control circuit. The nickel-cadmium battery charging control circuit includes a power converter, a filter, a current detection subcircuit, a voltage detection subcircuit, a current loop subcircuit, a voltage loop subcircuit, a battery temperature detection subcircuit, a PWM generation subcircuit, an air cooling overtemperature fault detection subcircuit, and a mode switching subcircuit.

[0043] The power converter is used to convert the input power voltage and output the required output voltage and output current; the output voltage and output current are filtered to remove ripple signals; the filtered output current enters the current detection subcircuit for detection, converted into the required voltage signal, and then output to the current loop subcircuit and the mode switching subcircuit; the filtered output voltage enters the voltage detection subcircuit for detection, converted into the required voltage signal, and then output to the voltage loop subcircuit; the current loop subcircuit modulates the converted output current signal with the current reference signal from the mode switching subcircuit and outputs the modulated signal to the cathode of the diode connected to the output of the voltage loop subcircuit; the voltage loop subcircuit modulates the converted output voltage signal with the voltage reference signal from the mode switching subcircuit and outputs the modulated signal to the PWM generation circuit and the anode of the diode connected to the current loop subcircuit; the PWM generation circuit processes the signal output by the voltage loop subcircuit to obtain a drive signal and sends it to the power converter; the battery temperature detection subcircuit converts the detected battery temperature into the required voltage signal and outputs it to the mode switching subcircuit; the air cooling and over-temperature fault detection subcircuit converts air cooling equipment fault and over-temperature fault into logic signals and outputs them to the mode switching subcircuit;

[0044] The mode switching subcircuit includes a constant voltage to floating charge mode recognition circuit, a floating charge to constant voltage mode recognition circuit, a normal or fault mode recognition circuit, a voltage loop reference switching circuit, and a current loop reference switching circuit. The constant voltage to floating charge mode recognition circuit performs a logical operation on the converted output current signal and the converted battery temperature and outputs the result to the voltage loop reference switching circuit; the floating charge to constant voltage mode recognition circuit also performs a logical operation on the converted output current signal and the converted battery temperature and outputs the result to the voltage loop reference switching circuit; the voltage loop reference switching circuit processes the two input mode recognition signals and outputs them to the voltage loop subcircuit; the normal or fault mode recognition circuit processes the logic signals output by the air cooling and over-temperature fault detection subcircuits and outputs them to the current loop reference switching circuit, which then processes the signals and outputs them to the current loop subcircuit.

[0045] Furthermore, when the normal or fault mode recognition circuit identifies that the output logic of the air cooling or over-temperature fault detection circuit is a normal mode, the circuit outputs a logic 0 to the current loop reference switching circuit. The current loop reference switching circuit receives the logic 0 output by the normal or fault mode recognition circuit and outputs a signal to set the charging current to C to the current loop sub-circuit. When the normal or fault mode recognition circuit identifies that the output logic of the air cooling or over-temperature fault detection circuit is a fault mode, the circuit outputs a logic 1 to the current loop reference switching circuit. The current loop reference switching circuit receives the logic 1 output by the normal or fault mode recognition circuit and outputs a signal to set the charging current to C0 to the current loop sub-circuit.

[0046] Wherein, C is 90%-110% of the capacity R in the rated capacity RAh of the selected nickel-cadmium battery, and C0 is 30%-50% of the charging current value C set by the current loop reference switching circuit in normal mode;

[0047] Furthermore, the constant voltage to floating charge mode identification circuit includes a current value judgment circuit 1, a current value judgment circuit 2, a timer 1 circuit, a battery temperature judgment circuit 1, and an OR logic gate. The current value judgment circuit 1 judges the converted output current signal and outputs it to the OR logic gate. The judgment logic is that when the output current is lower than the current value C1, it outputs a logic 1. The current value judgment circuit 2 judges the converted output current signal and outputs it to the timer 1 circuit. The judgment logic is that when the output current is higher than the current value C2, it outputs a logic 1. After being processed by the timer 1 circuit, the circuit output is output to the OR logic gate. The logic of the timer 1 circuit is that when the duration of the output logic 1 of the current value judgment circuit 2 is greater than T1, the timer 1 circuit outputs a logic 1. The battery temperature judgment circuit 1 judges the converted battery temperature signal and outputs it to the OR logic gate. The judgment logic is that when the battery temperature is lower than M1, the output is a logic 1.

[0048] Among them, C1 is 10%-20% of the charging current value C set by the current loop reference switching circuit in normal mode; C2 is 80%-90% of the charging current value C set by the current loop reference switching circuit in normal mode; T1 is 1.2-2 times the total time T required to fully charge the empty battery to the floating charge mode in normal mode; the total time T is the sum of the constant current mode time and the constant voltage mode time during the charging process of the empty battery; M1 is the low temperature point when the battery discharge performance is lower than 80% of the normal temperature of 25°C.

[0049] The floating charge to constant voltage mode recognition circuit includes a current value judgment circuit 3, a battery temperature judgment circuit 2, a timer 2 circuit, and an AND logic gate. The current value judgment circuit 3 judges the converted output current signal and outputs it to the AND logic gate and the timer 2 circuit. The judgment logic is that when the output current is higher than the current value C3, the output is a logic 1. The timer 2 circuit logic is that when the output logic 1 of the current value judgment circuit 3 lasts longer than T2, the timer 2 circuit outputs a logic 1. The battery temperature judgment circuit 2 judges the converted battery temperature signal and outputs it to the OR logic gate. The judgment logic is that when the battery temperature is higher than M2, the output is a logic 1.

[0050] Among them, C3 is 70%-80% of the charging current value C set by the current loop reference switching circuit in normal mode; T2 should be greater than the duration of the constant voltage charging mode in normal mode; M2 is the low temperature point when the battery discharge performance is higher than 90% under normal temperature of 25°C. The filter should be a high-frequency filter. The high-frequency filter is selected to obtain smoother output current and output voltage signals. The current detection sub-circuit should be selected with a bandwidth higher than the switching frequency bandwidth of the power converter to ensure a fast dynamic response to the output current. The regulator design in the current loop sub-circuit should meet the criterion of current loop stability, and a PI regulator is preferred; the regulator design in the voltage loop sub-circuit should meet the criterion of voltage loop stability,

[0051] A PID regulator is preferred; the power converter should be a DC-DC conversion form or an AC-DC conversion form to match the charging characteristics requirements of the battery.

[0052] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as generally understood by those skilled in the art in the art to which the present invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and, unless defined as such, should not be interpreted in an idealized or overly formal sense. The specific embodiments described above further illustrate the objectives, technical solutions, and beneficial effects of the present invention in detail. It should be understood that the above description is merely a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. An adaptive dual closed-loop charging control method, characterized in that: It is implemented based on a nickel-cadmium battery charging control circuit, which includes a power converter, a filter, a current detection subcircuit, a voltage detection subcircuit, a current loop subcircuit, a voltage loop subcircuit, a battery temperature detection subcircuit, a PWM generation subcircuit, an air cooling overtemperature fault detection subcircuit, and a mode switching subcircuit; The power converter is used to convert the input power supply voltage and output the required output voltage and output current; the output voltage and output current are filtered to remove ripple signals; The filtered output current enters the current detection subcircuit for detection, is converted into the required voltage signal, and then output to the current loop subcircuit and the mode switching subcircuit; The filtered output voltage enters the voltage detection subcircuit for detection, is converted into the required voltage signal, and is then output to the voltage loop subcircuit. The current loop subcircuit modulates the converted output current signal with the current reference signal from the mode switching subcircuit, and outputs the modulated signal to the cathode of a diode connected to the output of the voltage loop subcircuit. The voltage loop circuit modulates the converted output voltage signal with the voltage reference signal from the mode switching subcircuit, and outputs the modulated signal to the PWM generation circuit and the anode of a diode connected to the current loop subcircuit. The PWM generation circuit processes the signal output by the voltage loop circuit, obtains a drive signal, and sends it to the power converter. The battery temperature detection subcircuit converts the detected battery temperature into the required voltage signal and outputs it to the mode switching subcircuit; the air cooling and over-temperature fault detection subcircuit converts air cooling device faults and over-temperature faults into logic signals and outputs them to the mode switching subcircuit; The mode switching subcircuit includes a constant voltage to floating charge mode recognition circuit, a floating charge to constant voltage mode recognition circuit, a normal or fault mode recognition circuit, a voltage loop reference switching circuit and a current loop reference switching circuit; the constant voltage to floating charge mode recognition circuit performs a logical operation on the converted output current signal and the converted battery temperature and outputs the result to the voltage loop reference switching circuit; the floating charge to constant voltage mode recognition circuit also performs a logical operation on the converted output current signal and the converted battery temperature and outputs the result to the voltage loop reference switching circuit; the voltage loop reference switching circuit processes the two input mode recognition signals and outputs them to the voltage loop subcircuit; the normal or fault mode recognition circuit processes the logic signals output by the input air cooling and overtemperature fault detection subcircuits and outputs them to the current loop reference switching circuit, and then outputs them to the current loop subcircuit after being processed by the electric loop current reference switching circuit.

2. The adaptive dual closed-loop charging control method according to claim 1, characterized in that: When the normal or fault mode recognition circuit identifies that the output logic of the air cooling or over-temperature fault detection circuit is in normal mode, the circuit outputs logic 0 to the current loop reference switching circuit. The current loop reference switching circuit receives the logic 0 output by the normal or fault mode recognition circuit and outputs a signal for setting the charging current to C to the current loop sub-circuit. When the normal or fault mode recognition circuit identifies that the output logic of the air cooling or over-temperature fault detection circuit is in fault mode, the circuit outputs logic 1 to the current loop reference switching circuit. The current loop reference switching circuit receives the logic 1 output by the normal or fault mode recognition circuit and outputs a signal for setting the charging current to C0 to the current loop sub-circuit. Wherein, C is 90%-110% of the capacity R in the rated capacity RAh of the selected nickel-cadmium battery, and C0 is 30%-50% of the charging current value C set by the current loop reference switching circuit in normal mode.

3. The adaptive dual closed-loop charging control method according to claim 1, characterized in that: The constant voltage to floating charge mode identification circuit includes a current value judgment circuit 1, a current value judgment circuit 2, a timer 1 circuit, a battery temperature judgment circuit 1 and an OR logic gate; the current value judgment circuit 1 judges the converted output current signal and outputs it to the OR logic gate, and the judgment logic is that when the output current is lower than the current value C1, it outputs logic 1; the current value judgment circuit 2 judges the converted output current signal and outputs it to the timer 1 circuit, and the judgment logic is that when the output current is higher than the current value C2, it outputs logic 1, and after being processed by the timer 1 circuit, it outputs it to the OR logic gate, and the logic of the timer 1 circuit is that when the output logic of the current value judgment circuit 2 is 1 for a duration greater than T1, the timer 1 circuit outputs logic 1; the battery temperature judgment circuit 1 judges the converted battery temperature signal and outputs it to the OR logic gate, and the judgment logic is that when the battery temperature is lower than M1, the output logic is 1; Among them, C1 is 10%-20% of the charging current value C set by the current loop reference switching circuit in normal mode; C2 is 80%-90% of the charging current value C set by the current loop reference switching circuit in normal mode; T1 is 1.2-2 times the total time T required to fully charge the empty battery to the floating charge mode in normal mode; the total time T is the sum of the constant current mode time and the constant voltage mode time during the charging process of the empty battery; M1 is the low temperature point when the battery discharge performance is lower than 80% of the normal temperature of 25°C.

4. The adaptive dual closed-loop charging control method according to claim 1, characterized in that: The floating charge to constant voltage mode recognition circuit includes a current value judgment circuit 3, a battery temperature judgment circuit 2, a timer 2 circuit, and an AND logic gate; the current value judgment circuit 3 judges the converted output current signal and outputs it to the AND logic gate and the timer 2 circuit. The judgment logic is to output logic 1 when the output current is higher than the current value C3; The logic of the timer 2 circuit is that when the output logic of the current value judgment circuit 3 is 1 for a duration greater than T2, the timer 2 circuit outputs logic 1; the battery temperature judgment circuit 2 judges the converted battery temperature signal and outputs it to the OR logic gate. The judgment logic is that when the battery temperature is higher than M2, the output logic is 1; Among them, C3 is 70%-80% of the charging current value C set by the current loop reference switching circuit in normal mode; T2 should be greater than the duration of the constant voltage charging mode in normal mode; M2 is the low temperature point when the battery discharge performance is higher than 90% of the normal temperature of 25°C.

5. A charger comprising the adaptive dual closed-loop charging control method according to claim 1, characterized in that: The filter should be a high-frequency filter. The purpose of selecting a high-frequency filter is to obtain smoother output current and output voltage signals.

6. A charger comprising the adaptive dual closed-loop charging control method according to claim 1, characterized in that: The current sensing subcircuit should be selected with a bandwidth higher than the switching frequency bandwidth of the power converter to ensure a fast dynamic response to the output current.

7. A charger comprising the adaptive dual closed-loop charging control method according to claim 1, characterized in that: The design of the regulator in the current loop subcircuit should meet the criterion of current loop stability, and the regulator is a PI regulator.

8. A charger comprising the adaptive dual closed-loop charging control method according to claim 1, characterized in that: The design of the regulator in the voltage loop subcircuit should meet the voltage loop stability criterion, and the regulator is a PID regulator.

9. A charger using the adaptive dual closed-loop charging control method according to claim 1, characterized in that: The power converter should be in the form of DC-DC conversion or AC-DC conversion.

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