Alternating-current solid-state power controller

Abstract

The invention discloses an alternating-current solid-state power controller. The alternating-current solid-state power controller comprises a microprocessor which directly collects alternating-current electric signals through an AD port, polarity judgment and alternating-current sampling are achieved through a software algorithm, and the zero-crossing switching function, the signal collection function, the protection function and the like of the solid-state power controller are achieved through a driving protection circuit composed of a trigger and a comparator. The alternating-current solid-state power controller is suitable for power-frequency alternating-current power distribution systems, variable-frequency alternating-current power distribution systems and the like.

Description

Technical Field

[0001] The present invention relates to the field of SSPC, and in particular to an AC solid-state power controller. Background Art

[0002] With the improvement of the electrification level of ships, tanks, aircraft and other equipment, and the emergence of high-energy weapons on board, the power supply and distribution systems of new equipment are becoming more and more integrated, modular and intelligent, and the original protection switches such as circuit breakers and relays will gradually be replaced by SSPCs. At present, AC SSPCs are mostly used in 115V400HZ AC power distribution systems of military aviation equipment, but are rarely used in ships, tanks, civil aircraft and other equipment, mainly because the power supply systems of the above equipment mostly use 220V 50Hz industrial frequency AC and variable frequency AC, and the existing SSPCs cannot meet the requirements.

[0003] The solid-state power controller has load power supply switching function, load current, voltage and other information collection function, as well as overload and short circuit protection function. Figure 1 , the microprocessor of the AC solid-state power controller receives the bus instruction and outputs the CMD control signal to the programmable logic device. In order to realize the zero voltage opening and zero current closing of the load, the AC SSPC has an additional current zero-crossing detection circuit and a voltage zero-crossing detection circuit, and the result of the zero-crossing detection is provided to the programmable logic device. According to the received zero-crossing detection result, the programmable logic device controls two back-to-back power switches through the driving logic to realize the soft switching of the AC load. In the load power supply circuit, there is a sampling circuit. The current, voltage and other signals of the load are converted to effective values ​​after the conditioning circuit and provided to the microprocessor for sampling, so that under normal circumstances, the microprocessor can obtain the real-time current and on-off status information of the load, and implement overload and short-circuit protection under abnormal circumstances. The overload protection is protected by the microprocessor through an algorithm based on the real-time collected current value, and the short-circuit protection is completed by the hardware logic, and after the protection is completed, a short-circuit signal is sent to the microprocessor to notify the microprocessor that a short circuit has occurred in the channel. The above AC SSPC has the following disadvantages: 1. The sampling circuit uses an effective value conversion chip. When the AC frequency drops to 50Hz or even lower, the sampling stabilization time will increase, affecting the acquisition value delay and overcurrent protection function. 2. In order to achieve zero voltage turn-on and zero current turn-off, additional current zero-crossing detection circuit and voltage zero-crossing detection circuit are required, and the hardware design is too complicated. 3. Due to the bidirectional characteristics of AC, the sampling circuit and zero-crossing detection circuit need to have a negative power supply and a negative reference, which increases the complexity of the power supply circuit. 4. Programmable logic devices are necessary devices and cannot be omitted. Summary of the invention

[0004] The purpose of the present invention is to solve the problems in the prior art and provide a novel AC solid-state power controller.

[0005] In order to achieve the above object, the present invention provides a technical solution: an AC solid-state power controller, comprising:

[0006] microprocessor;

[0007] Power unit;

[0008] Reference power supply unit: used to determine the quasi-power supply Vref, the positive short-circuit threshold value Vthh, the negative short-circuit threshold value Vthl and the bias point voltage Vmid; and,

[0009] Acquisition unit: The current signal XI is collected through the voltage across the resistor Rs of the power unit, and the output signal is given to the AD port of the microprocessor through the operational amplifier circuit based on the bias voltage Vmid. The output signal of the operational amplifier circuit is also provided to the comparator of the drive protection unit for short-circuit judgment. The voltage signal acquisition includes input voltage and power output voltage acquisition. The AC bus input end generates a bus voltage signal X-Vb based on the bias point through a high-resistance resistor and a bias point voltage divider for the microprocessor to collect. The power output end of the solid-state power controller generates a power output voltage signal X-Vo based on the bias point through a high-resistance resistor and a bias point voltage divider for the microprocessor to collect. The N line end generates a power output voltage signal X-Vn based on the bias point through a high-resistance resistor and a bias point voltage divider for the microprocessor to collect.

[0010] As a preferred solution for the AC solid-state power controller, the power supply Vcc generates a reference power supply Vref through a reference source chip. The reference power supply Vref passes through voltage-dividing resistors R1, R2, R3, and R4, where R1=R4 and R2=R3. The voltage division generates a positive short-circuit threshold value Vthh and a negative short-circuit threshold value Vthl. The intermediate voltage generates a bias point voltage Vmid through an operational amplifier follower circuit.

[0011] As a preferred solution for the AC solid-state power controller, the driving protection unit: the current acquisition signal XI is respectively connected to the negative input terminal of the comparator U1 and the positive input terminal of the comparator U2, the positive short-circuit threshold value Vthh is connected to the positive input terminal of the comparator U1, the output terminal of the comparator U1 is connected to the negative terminal of the diode D1, the negative short-circuit threshold value Vthl is connected to the negative input terminal of the comparator U1, the output terminal of the comparator U1 is connected to the negative terminal of the diode D2, and the short-circuit interrupt signal / SCP generated by the positive terminals of the diodes D1 and D2 is sent to the interrupt port of the microprocessor, the short-circuit interrupt signal / SCP is connected to the power supply Vcc through the resistor R5, and the short-circuit interrupt signal / SCP is connected to the D triggers U3 and U4 through the resistor R6. The D flip-flops U3 and U4 The terminals are used to receive the control signal / CMD from the microprocessor, and the D flip-flops U3 and U4 The terminals are connected to the power supply Vcc, and the D flip-flop U3 The terminal is used to receive the zero-crossing signal / SET-UP from the microprocessor, and the D flip-flop U3 The end is used to output the driving signal RD-UP for driving the upper power switch of the power unit, and the D trigger U4 The zero-crossing signal / SET-DW from the microprocessor is terminated, and the D flip-flop U4 The end is used to output a driving signal RD-DW for driving the lower power switch of the power unit.

[0012] Compared with the prior art, the beneficial effects of the present invention are at least as follows: (1) the AC signal acquisition circuit is simplified, and the signal is directly collected by the microprocessor after resistor voltage division and voltage bias, without the need for a true effective value conversion chip; (2) a single power supply is used, and no positive or negative power supply is required; (3) the zero-crossing detection microprocessor collects current and voltage signals for comprehensive judgment, and no special zero-crossing detection circuit is required; (4) a D-type flip-flop is used to implement the zero-crossing switch, short-circuit protection latch, etc. of the solid-state power controller, without the need for a programmable logic device. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of a prior art 115V AC solid-state power controller.

[0014] Figure 2 It is a schematic diagram of the structure of the present invention.

[0015] Figure 3 It is a structural schematic diagram of the data acquisition circuit of the present invention.

[0016] Figure 4 It is a schematic diagram of the structure of the reference power supply and the driving protection circuit of the present invention. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below by means of specific embodiments in combination with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0018] See also Figure 2 , the figure shows an AC solid-state power controller. Figure 1 The AC solid-state power controller of this embodiment has an AC signal acquisition circuit that is simplified.

[0019] See also Figure 3, the AC signal acquisition circuit includes: the three terminals of AC bus input terminal, Power Out output terminal and N line terminal are respectively divided by resistors and bias terminal Vmid, and the voltage acquisition signal after voltage division is directly input into the microprocessor for AD sampling. The microprocessor judges the polarity of the signal according to the comparison between the instantaneous value of AD acquisition and the bias terminal voltage. When the acquisition value is greater than the bias terminal voltage, the polarity is positive, otherwise the polarity is negative. The bus input voltage can be calculated as Vb-Vn, and the power output voltage can be calculated as Vo-Vn. The current signal Is is collected by the differential voltage at both ends of the sampling resistor Rs, and then input into the microprocessor for AD sampling after passing through the operational amplifier circuit based on the bias voltage Vmid. The microprocessor can calculate the instantaneous value of the current signal Is as the absolute value of the difference between the AD acquisition value voltage VIs and the bias terminal voltage Vmid multiplied by the proportional coefficient. Similarly, the polarity of the current signal is determined according to the polarity of VIs. When VIs is greater than the bias endpoint voltage (it can be slightly higher than the bias point voltage according to actual conditions), the current signal polarity is positive. When VIs is less than the bias endpoint voltage (it can be slightly lower than the bias point voltage according to actual conditions), the current signal polarity is negative. The microprocessor directly performs overload protection calculations based on the instantaneous value of Is. When reporting is required, the microprocessor uses the absolute value to calculate the secondary moving average, multiplies it by a coefficient, and converts it into the effective value of the current for reporting.

[0020] The microprocessor generates a zero-crossing signal according to the polarity of the current and voltage signals, and realizes the zero-crossing switch function of the SSPC with the on-off command. Figure 4 , the power reference circuit includes: a reference source, resistors R1, R2, R3, R4, etc. The voltage Vcc generates a positive short-circuit threshold value Vthh and a negative short-circuit threshold value Vthl according to the voltage division of resistors R1, R2, R3, and R4. The current signal Is enters the comparator U1 and U2 for comparison with the positive short-circuit threshold value Vthh and the negative short-circuit threshold value Vthl respectively. When a short circuit occurs between the output end of Power Out and the N-line end, the voltage collected by the current signal Is is greater than the positive or negative short-circuit threshold value, and the corresponding comparator outputs a low signal. After passing through the D1 or D2 diode, the short-circuit interrupt signal / SCP is set low, so that the trigger U3 drive signal RD-UP and the trigger U4 drive signal RD-DW are both low, thereby disconnecting the upper and lower power switches. In addition, after the microprocessor receives the short-circuit interrupt signal / SCP, the short-circuit protection flag is valid, and the / CMD control signal is set high. The reclosing flag is started on demand. During the reclosing period, the SSPC external command is not responded to. The unfinished reclosing function is terminated by shutting down the SSPC external command. The short-circuit protection flag is cleared by factors such as reset command or successful reclosing opening or premature termination of the reclosing function due to shut-down command.

[0021] When the microprocessor receives the turn-on instruction, it sets the / CMD control signal low and outputs it to the D flip-flops U3 and U4, and at the same time determines the bus input voltage polarity VP and the output polarity VN. When VN is positive, the microprocessor outputs a falling edge signal / SET-UP to the D flip-flop U3, and the D flip-flop U3 turns on the upper power switch and latches it through the RD-UP drive signal; when VP is positive, the microprocessor outputs a falling edge signal / SET-DW to the D flip-flop U4, and the D flip-flop U4 turns on the lower power switch and latches it through the RD-DW drive signal. When the microprocessor receives the shutdown command, it sets the / CMD control signal high and outputs it to the two D flip-flops U3 and U4, and at the same time determines the polarity of the current signal. When the polarity of the current signal is negative, the microprocessor outputs a falling edge signal / SET-UP to the D flip-flop U3, and the D flip-flop U3 turns off the upper power switch and latches it through the RD-UP drive signal; when the polarity of the current signal is positive, the microprocessor outputs a falling edge signal / SET-DW to the D flip-flop U4, and the D flip-flop U4 turns off the lower power switch and latches it through the RD-DW drive signal.

[0022] The above only expresses the implementation mode of the present invention, and its description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. An AC solid-state power controller, characterized in that: include: microprocessor; Power unit; Reference power supply unit: used to determine the quasi-power supply Vref, the positive short-circuit threshold value Vthh, the negative short-circuit threshold value Vthl and the bias point voltage Vmid; as well as, Acquisition unit: The current signal XI is collected through the voltage across the resistor Rs of the power unit, and the output signal is given to the AD port of the microprocessor through the operational amplifier circuit based on the bias voltage Vmid. The output signal of the operational amplifier circuit is also provided to the comparator of the drive protection unit for short-circuit judgment. The voltage signal acquisition includes input voltage and power output voltage acquisition. The AC bus input end generates a bus voltage signal X-Vb based on the bias point through a high-resistance resistor and a bias point voltage divider for the microprocessor to collect. The power output end of the solid-state power controller generates a power output voltage signal X-Vo based on the bias point through a high-resistance resistor and a bias point voltage divider for the microprocessor to collect. The N line end generates a power output voltage signal X-Vn based on the bias point through a high-resistance resistor and a bias point voltage divider for the microprocessor to collect.

2. An AC solid-state power controller according to claim 1, characterized in that: The power supply Vcc generates a reference power supply Vref through a reference source chip. The reference power supply Vref passes through voltage-dividing resistors R1, R2, R3, and R4, where R1=R4 and R2=R3. The voltage division generates a positive short-circuit threshold value Vthh and a negative short-circuit threshold value Vthl. The intermediate voltage generates a bias point voltage Vmid through an operational amplifier follower circuit.

3. The AC solid-state power controller according to claim 1, characterized in that: Driving protection unit: the current acquisition signal XI is connected to the negative input terminal of the comparator U1 and the positive input terminal of the comparator U2 respectively, the positive short-circuit threshold value Vthh is connected to the positive input terminal of the comparator U1, the output terminal of the comparator U1 is connected to the negative terminal of the diode D1, the negative short-circuit threshold value Vthl is connected to the negative input terminal of the comparator U1, the output terminal of the comparator U1 is connected to the negative terminal of the diode D2, the short-circuit interrupt signal / SCP generated by the positive terminals of the diodes D1 and D2 is sent to the interrupt port of the microprocessor, the short-circuit interrupt signal / SCP is connected to the power supply Vcc through the resistor R5, and the short-circuit interrupt signal / SCP is connected to the D triggers U3 and U4 through the resistor R6. The D flip-flops U3 and U4 The terminals are used to receive the control signal / CMD from the microprocessor, and the D flip-flops U3 and U4 The terminals are connected to the power supply Vcc, and the D flip-flop U3 The terminal is used to receive the zero-crossing signal / SET-UP from the microprocessor, and the D flip-flop U3 The end is used to output the driving signal RD-UP for driving the upper power switch of the power unit, and the D trigger U4 The zero-crossing signal / SET-DW from the microprocessor is terminated, and the D flip-flop U4 The end is used to output a driving signal RD-DW for driving the lower power switch of the power unit.

4. The AC solid-state power controller according to claim 2, characterized in that: The resistance of resistor R5 is more than 10 times that of resistor R6 to ensure that the D flip-flop U3 is closed when the short-circuit interrupt signal / SCP is at a low level. The terminal can detect a low level.

5. The AC solid-state power controller according to claim 3, characterized in that: The reference power supply unit generates a bias point voltage Vmid, and the acquisition unit acquires the current and voltage signals of the power unit based on the bias voltage Vmid and the operational amplifier circuit and provides them to the AD port of the microprocessor for acquisition. The microprocessor makes polarity judgment according to the acquired current and voltage signals, outputs control instructions to the drive protection unit to realize the zero-crossing switch of the AC solid-state power controller, and performs overcurrent protection calculation according to the acquired instantaneous current value. In addition, the AC effective value calculation is realized through an algorithm and outputs feedback.

Images